WO2016056947A1 - Method for processing alumina-containing raw material and method for breaking down alumina-containing raw material during processing - Google Patents

Abstract

The invention relates to chemistry and metallurgy and is intended for the processing and breakdown of alumina-containing raw material. A processing method is carried out as a cyclic process that includes: a breakdown stage, in which raw material is decomposed using a reagent solution containing ammonium bisulphate and sulphuric acid and the resultant slurry is separated, producing undecomposed solid residues, which are rinsed with water, and an alum mother solution, wherein the alum mother solution and the rinse waters are collected separately; a purification stage, in which the rinse waters are purified of iron then combined with the alum mother solution and cooled, and crystals of ammonium alum are isolated, wherein the sulphuric acid used for the reagent solution in the breakdown stage is separated off; a precipitation stage, in which aluminium hydroxide is precipitated from the purified alum solution with ammonia; a separation stage for separating off aluminium hydroxide; a stage for obtaining solid ammonium sulphate and a stage for the thermal decomposition thereof into ammonium bisulphate and ammonia, which can be used in the breakdown stage, during the preparation of the reagent solution, and in the precipitation stage, respectively. The invention makes it possible to process any alumina-containing raw material at low temperatures, to reduce reagent loss and to reduce the volume of reagents which needs to be replenished during the process.

Description

 A method for processing alumina-containing raw materials and a method for opening alumina-containing raw materials

 during its processing

Technical field

 The invention relates to chemistry and metallurgy, and in particular, to a method for processing alumina-containing raw materials and a method of opening such raw materials during processing to obtain metallurgical alumina and related products.

State of the art

 Methods of processing alumina-containing (alumina) raw materials, which include the first invention of the proposed group, are widely known.

So, alkaline methods are known (Bayer method and its modification) used for processing alumina-containing raw materials (Liner A.I., Eremin N.I., Liner Yu.A., Pevzner I.Z. Production of alumina . M, Metallurgy, 1978, 394 pp. [1]; Troitsky I.A., Zheleznov V.A. Metallurgy of aluminum. - M., Metallurgy, 1977, p. 42-1 16 [2]; RF patent JV ° 2360865, published July 10, 2009 [3]; RF patent 2193525, published 27.1 1.2002

[four]). These methods require the use of high-quality (ie, low silica) bauxite feedstock, which is becoming increasingly less accessible due to the fact that the mining industrial reserves of such bauxites are everywhere limited. Using the Bayer method and its analogues for processing of low-quality bauxite, as well as aluminosilicate raw materials, for example, nepheline, is irrational for technological and economic reasons. The reason is that in such a technological process, silicon oxide enters into chemical interaction with alkali, and a large amount of both alkali and aluminum is lost in its bonding due to the formation of a mixed compound - sodium hydroaluminosilicate.

Alkaline methods are adjoined by methods based on the method of sintering raw materials with limestone or with limestone and soda or alkali, followed by washing the sinter with water or an aqueous solution of soda: Matveev V. A. Physico-chemical and technological bases for increasing the efficiency of complex processing of nepheline-containing raw materials by acid methods. Diss. doc tech. Sciences, Apatity, 2009, 299 pp. [5]. At present, about 40% of the alumina produced in Russia is obtained from the Kola nepheline and nepheline syenite from Siberian deposits using this method (see [5], as well as: Isakov EA, Pikalevskoe Alumina Association under new conditions. Non-ferrous metals, 1997 , N ° 4, p. 8 [6]). However, the significant limitations of these methods are the high energy intensity and the need to obtain and process a large number of associated sodium-calcium-silicate products. In the future, taking into account rising energy prices, the economic efficiency of the sintering method may decrease significantly.

An alternative to alkaline and sintering methods for processing low-grade bauxite, as well as non-bauxite aluminum raw materials (aluminosilicates) are acid methods, the use of which allows separation of silica already in the first stages of the process without input additional reagents for its binding [1, 2, 5]. In addition, acid methods are much less energy intensive than sinter methods.

Known are nitric acid methods of processing alumina raw materials (see [1, 5], and also: Vaytner VV Research of nitric acid processing of aluminosilicates to produce alumina. Diss. Candidate of Technical Sciences, Ekaterinburg, 2004, 146 p. . [7] and RF patents: N ° 2202516, publ. 04/20/2003 [8]; JV "2215690, publ. 10.11.2003 [9]; tf ° 2372290, publ. 10.1 1.2009 [10];" 2460691, publ. 10.09.2012 [11]). These methods (in various versions) include processing the raw material with hot concentrated nitric acid, filtering the resulting pulp with washing the precipitate, further processing of the filtrate with the separation of intermediate aluminum compounds and their separation from iron compounds, as well as mainly include thermal hydrolysis of these intermediate aluminum compounds with the regeneration of nitric acid and the production of hydrated or dry alumina. All nitric acid methods are characterized by a number of common disadvantages, including: poor filterability of pulps obtained after decomposition of easily opened aluminosilicate raw materials, for example, nepheline ores and concentrates (even when using flocculants), which makes the process more expensive and makes it more labor intensive; a small degree of opening during direct decomposition of bauxite and kaolinite-boehmite raw materials, making them necessary to pre-calcine, which also makes the process more expensive by increasing its energy intensity; insufficient degree of regeneration of nitric acid and the need for the supply and expenditure of fresh acid in large quantities; environmental hazard associated with the formation of azo oxides This and significant economic losses associated with their conversion to nitric acid.

Hydrochloric acid methods are known (see [7], as well as: Shvartsman B.Kh. Acidic methods for processing alumina-containing raw materials. M: Tsvetmetinformatsiya, 1964. 82 pp. [12]; Pustilnik G.L., Pevzner I.Z. Ki - slot methods for processing low-quality aluminum-containing raw materials. M: Tsvetmetinformatsiya, 1978. 52 p. [13]). These methods include preliminary roasting of the raw material, leaching, separation of silica slurry by filtration, iron removal using various options, including by evaporation of the filtrate solution to obtain crystals of the "yellow salt" (A1C1 ₃ 6H ₂ O with impurities iron), which, after cooling, is washed with hydrochloric acid to obtain a “white salt” (pure crystals of aluminum chloride), which, in turn, is calcined at temperatures above 1000 ° C to obtain alumina and regeneration of hydrogen chloride in the form of a mixture with in pairs returning after absorption to the head of the process in the form of 30% hydrochloric acid. In recent years, interest in these methods has resumed in connection with the creation of effective plants for the calcination of chlorides and the recovery of hydrochloric acid (Herbert Weissenbaeck, Benedikt Nowak, Dieter Vogl, Horst Krerm. Development of Chloride Based Metal Extraction Technologies - Advancements and Setbacks, Proceedings of Nickel-Cobalt-Copper Conference of ALTA-2013, 29 May - 1 June, 2013 Perth, WA, Melbourne, Australia, p. 360 [14]). However, alumina obtained by a similar processing technology requires additional purification from iron [13]. In recent years, Orbit Aluminae Inc. (Canada) has proposed a method based on this technology, but including additional operations for cleaning iron by extraction tion (RF patent N22471010, publ. 12/27/2012 [15]). The main disadvantages of the methods [7, 12–15] are the increased requirements for the corrosion resistance of equipment, as well as the need for significant energy costs for acid regeneration under conditions when the cost of energy rises faster than the price of metallurgical alumina [7].

The sulfuric acid methods of processing alumina-containing raw materials are widely known (see [1, 7, 12], as well as: Liner, Yu.A. Complex processing of aluminum-containing raw materials by acid methods. M: Nauka, 1982, 208 p. [16] ; Zapolsky AK, Sazhin VS, Zakharova NN Crystallization of basic aluminum sulfate salts. Chemistry and technology of alumina. Novosibirsk, Nauka, 1971, pp. 430 - 438 [17]; Zapolsky A. K. , Sulfuric acid processing of high-silicon aluminum raw materials. Kiev, Naukova Dumka, 1981, pp. 198-200 [18]; Paweena Numluk and Aphiruk Chaisena. Sulfuric Acid and Ammonium Sulfate Leaching of Alumina from Lampang Clay // E- Jou rnal of Chemistry. 2012. V 9, No.3. p. 1364 - 1372, http://www.ejchem.net [19]). In accordance with these methods, pre-calcined or crude ore is treated with sulfuric acid. After purification from iron, sulfate salts of aluminum are extracted from sulfuric acid solutions: aluminum sulfate, aluminum alum or basic salts, from which alumina is obtained by direct calcination or calcination of aluminum hydroxide after its preliminary isolation with ammonia [12]. One of the main advantages of using sulfuric acid for processing alumina raw materials is the possibility of using cheaper equipment due to the considerable experience in corrosion protection gained in sulfuric acid production and other industries. In the case of using the sulfuric acid decomposition method with subsequent separation of aluminum minium in the form of aluminum-ammonium alum, the suspension is filtered after decomposition, and ammonium sulfate is added to the filtrate; in order to prevent the formation of iron ammonium alum co-crystallizing with the intermediate product, the residual iron is reduced to a divalent state using ammonium bisulfite ([12] and RF patent N ° 2337877, publ. 10.11.2008 [20]), aluminum shavings (Sandler E.M., Liner Yu.A., Liner A.I., Chizhikov D.M. Iron removal of products during the sulfuric acid method of processing nepheline. Non-ferrous metallurgy. Izv. Universities, 1962, N ° 2, s . 30 - 33 [21]) or other reducing agents, for example, sulfur dioxide (Funaki K. Sulfuric acid process for obtaining pure aluminum oxide from it s ores // Bull, of the Tokyo Inst, of Technology, 1980, No.l [22]). As with other acidic methods, after leaching using sulfuric acid methods, it is difficult to separate solid and liquid phases. In addition, the energy required for high-temperature drying (500 ° C) and direct firing (1300 ° C) of aluminum sulfates and their derivatives is not less than in the case of using hydrochloric acid methods, and the mixture of SO2 and SO3 gases obtained during firing requires additional capital and extinction high costs for the regeneration (synthesis) of sulfuric acid and its return to the head of the process for opening alumina raw materials.

Known alkaline-acid method according to the patent of the Russian Federation N22440296 (publ. 01.20.2012 [23]). In this method, the acid treatment, mainly using nitric acid, is not subjected to the feedstock, but to red mud obtained after the usual alkaline decomposition of the feedstock. The resulting solution was evaporated and the precipitate was thermally decomposed at temperatures up to 600 ° C to obtain sodium aluminate (a mixture of sodium oxides and aluminum). The method is defined by its authors as a universal Seal and eliminating the disadvantages of the Bayer alkaline method, since it allows to avoid the loss of aluminum with hydroaluminosilicates remaining in the sludge. This is substantiated in the patent [23] by the fact that the decomposition of hydroaluminosilicates as such is possible using a weak acid at ordinary temperature. However, the presence in this method of an alkaline treatment stage actually retains the above-mentioned disadvantages of the Bayer method, which are manifested in the processing of high-silica raw materials, and the additional extraction of aluminum compounds from the sludge does not cover the costs required for this. This is because alkaline (after the previous processing of the feedstock) sludge must first be neutralized with the consumption of a large amount of acid (and this is not reflected in the characteristics of the method [23]), before some additional amount of weak acid could have the expected effect on hydroaluminosilicates. The indicated large amount of acid is irretrievably lost, and the evaporation of the resulting weak solution and high-temperature thermal decomposition of the precipitate are associated with large additional energy costs. In addition, the strong moistening of the sludge that occurs when it is treated with weak acid results in the need for its reverse drying. Known methods for processing alumina-containing raw materials using salts or their solutions. For example, a method is known according to US patent l, 426.891 (publ. 08.22.1922 [24]) for processing aluminosilicates, in particular clay materials, by boiling in a solution of acid ammonium difluoride (NH F 'HF) to obtain precipitates containing aluminum hydroxide and aluminum fluoride, which are separated, dried and decomposed with acute water vapor at 300 + 400 ° C to obtain aluminum hydroxide and recirculation of hydrogen fluoride, as well as with semi- 15 000601

8

by preparing a solution containing mixed soluble double aluminum and ammonium fluorides, which are also decomposed by long-term thermal hydrolysis to produce aluminum hydroxide and recirculating ammonia and part of ammonium difluoride in the form of vapors. The method has several disadvantages, including the fact that a substantial part of the starting ammonium difluoride is consumed irrevocably, and serious requirements arise for equipment that must be stable in aggressive vapors of hydrofluoric acid and ammonium difluoride.

There are also known methods in accordance with which alumina-containing raw materials, mainly aluminosilicates in the form of clay materials, are calcined together with ammonium sulfate (USSR author's certificate JY ° 42067, publ. 03.31.1935 [25]; Ullmann B Encyklop- adie der technischen Chemie, Auflage, Urban & Schwarzenberg, Miinchen & Berlin. 1954, Bd. 3, 401 - 420 [26]; Grim RE Applied Clay Mineralogy, McGraw-Hill, New York, 1962, p. 335 - 345 [27]; G. Bayer, G. Kahr, and M. Mueller-Vonmoos. Reactions of ammonium sulphates with kaolinite and other silicate and oxide minerals, Clay Minerals, 1982, V.17, p. 271 - 283 [28] ) Calcination is carried out at temperatures of the order of 300–500 ° С to obtain a cake containing mixed aluminum and ammonium sulfates and aluminum sulfate, which are leached from this cake with water to obtain a solution of aluminum-ammonium alum. The latter are purified from iron impurities and converted to aluminum hydroxide by ammonia precipitation and stepwise precipitation by fluorides and ammonia. In this case, ammonia is in the technological cycle, since it is formed in the process head at the calcination stage. The disadvantages of this method are energy losses associated with the calcination of the entire volume of alumina-containing raw materials with ammonium sulfate, as well as irreversible PT / RU2015 / 000601

The apparent losses of ammonium sulfate are associated, first of all, with the decomposition of ammonium sulfate upon calcination with the release of sulfur dioxide. In addition, in the process of calcination, difficultly filtered complex compounds are formed, as well as compositions from which iron impurities are difficult to remove.

Closest to the proposed method is a method for processing alumina-containing raw materials, proposed by M. Buchner at the beginning of the 20s of the last century (patents [29]: Great Britain JV ° 195.998, published on 04/12/1922; United States .421, 493,320, published. 05/06/1924; USSR Nel 1489, publ. 30.09.1929). This method involves the implementation of a circular (closed cyclic) process, which includes the steps of: preliminary thermal decomposition of ammonium sulfate into ammonia and ammonium bisulfate, dissolution of the latter and processing of alumina raw materials with a hot solution of ammonium hydrogen sulfate (bisulfate) with or without an admixture of ammonium sulfate in an autoclave, filtering a solution of aluminum-ammonium alum and precipitating aluminum hydroxide from it with previously cleaved ammonia, separating ammonium sulfate from the mother liquor with return his head in the process. Unlike the methods [25 - 28], according to the specified method, the raw material is not directly introduced into the calcination process, which allows the decomposition of pure ammonium sulfate at temperatures below 300 ° C and reduces energy costs. On the other hand, treating alumina-containing raw materials with a hot solution of ammonium hydrogen sulfate does not lead to the loss of reagents in the form of sulfur dioxide. Finally, this method makes it possible to obtain intermediate compounds that are easily filtered and easily cleaned of iron. The method of M. Buchner refers to the so-called named methods in chemical technology, its second name is "Aloton"("Aloton") (Encyclopedic Die- 01

10 tionary of Named Processes in Chemical Technology / Ed. Alan E. Comyns Boca Raton: CRC Press LLC, .2000, 2-nd Ed., P.19 (Aloton) [30]). The method was implemented in pilot plants in Germany at the end of the 20s of the last century and in the USA (in Oregon) in 1944. However, it did not find industrial application. This is mainly due to the fact that, in the presence of widely available low-silica bauxite, the Bayer alkaline method has competitive advantages over the M. Buchner hydrosulphate method, which makes it possible to obtain alumina from aluminosilicates - it was not without reason that attempts to use it in subsequent years did not lead industrial implementation (Bretsznajder St. Otrzymywanie estow kwasu ortokrzemowego w fazie gazovey / St. retsznajder, W. Kawecki // Rocz. Chem, - 1955.- JY ° 29. - s. 287-299 [31]; Bretsznajder St. Nova metoda otrzymywania hutniczego tlenku glinovego i innych zwiazkow glinu z glin // Przem. Chem. - 1963, - V.42, Ne 12. - s. 677-683 [32]). In modern conditions, when low-silica bauxite has become a very limited resource, there is a reasonable reason for returning to the M. Buchner method, however, the existing shortcomings of the described hydrosulfate method [29] still limit the possibilities for its wide industrial implementation . The main disadvantage of the method of M. Buchner [29] is that it is not universal enough. The method is applicable only to easily openable aluminosilicate minerals (O'Connor, D. J. Alumina Extraction from Non-bauxitic Materials, Aluminum-Verlag, Diisseldorf, 1988, 159 p.

[33]), but it does not allow, with a high degree commensurate with the corresponding parameters of the Bayer method, to decompose and separate aluminum hydroxide (or alumina after calcining the hydroxide) from bauxite raw materials, including high-silicon bauxite raw materials, the processing of which - horn is currently the most urgent task. This is due to: a) a high content of aluminum in it and a low content of alkali and alkaline earth metals; b) with greater availability. Another disadvantage follows from the fact that the author of the method [29] recommends the implementation of the decomposition stage of even aluminosilicates in an autoclave at a relatively high temperature - at least 200 ° C (at lower temperatures, the required completeness of decomposition of the raw material is not achieved).

The disadvantage of this method is that too much energy is spent on evaporating the solution of residual ammonium sulfate during its processing in order to obtain solid ammonium sulfate, which is associated with the limited solubility of aluminum-ammonium alum in the mother liquor after decomposition using high concentrations of ammonium hydrosulfate in the initial solution reagent. This leads to the need to work with a diluted reagent solution, which, in turn, leads to the need for redistribution of a large amount of water in a circular process. Another disadvantage is caused by the irreversible consumption of the hydrosulfate reagent associated with the relatively high content of alkaline and alkaline earth elements in aluminosilicate raw materials. A gradual decrease in the effectiveness of the reagent solution from cycle to cycle associated with the use of reverse ammonium hydrogen sulfate in a circular process is associated with this.

Finally, the patents [29] did not disclose in detail the methods of purification from iron and silicon to obtain further pure alumina of metallurgical quality, although the information contained in the patents on the possibility of achieving such quality implies the presence of a sufficiently deep purification. The listed disadvantages are not eliminated when using one of the variants of the M. Buchner method [29], namely, using a solution of ammonium hydrosulfate mixed with ammonium sulfate as a reagent solution. The methods for opening alumina-containing raw materials during processing, to which the second invention relates, are included as one of the stages in the above methods [1 - 13, 15 - 29], and the patent of the Russian Federation 2153466 (publ. 27.07.2000 [39] ) is devoted only to this stage. According to method [39], the opening of alumina-containing raw materials involves heat treatment at a temperature of 400 550 ° C in the presence of a reagent — aqueous solutions of magnesium chloride and leaching of cake with the subsequent extraction of aluminum compounds from the resulting solution. This method is adjacent to the known sintering methods [5, 6] (in particular, related to the opening of raw materials), and therefore retains their drawback, which consists in high energy intensity, although it is somewhat reduced in this method.

The present invention related to the method of opening clay-alumina raw materials during its processing is closest to the opening method implemented in the M. Buchner method [29].

The opening of alumina-containing raw materials during their processing according to M. Buchner's method includes the preparation and heating of a reagent solution containing ammonium hydrosulfate, processing of the raw materials with this solution and separation of the resulting pulp into an undecomposed solid residue and a mother liquor of aluminum and other alum for the subsequent extraction of aluminum compounds from it. Unlike sintering methods [5, 6] and methods [25 - 28], in which the alumina-containing raw materials are calcined together with ammonium sulfate, when opening the raw materials according to the method of M. Buchner, it is not directly introduced into the calcination process, and the subsequent processing at temperatures of 400 ° C and higher, in contrast to the method [39], is also not required, which reduces energy costs. Moreover, this method allows to obtain easily filtered and easily cleaned from iron intermediate compounds.

However, the autopsy carried out in the M. Buchner method is applicable only to easily decomposable aluminosilicate minerals (see [33]), but not to bauxite raw materials, including high-silicon bauxite raw materials. In addition, despite the absence of high-temperature treatment (inherent, for example, to methods [25 - 28, 39]), it is preferable to decompose the raw materials in the M. Buchner method in an autoclave at a relatively high temperature (not less than 200 ° C), t .to. at lower temperatures, the required completeness of decomposition may not be achieved.

Disclosure of invention

The first of the proposed inventions related to a method of processing alumina-containing raw materials, is aimed at overcoming the above-mentioned disadvantages of the closest known method and achieving a technical result, which consists in the possibility of processing any alumina-containing raw materials with a simultaneous reduction in energy consumption as in initial processing of the entire mass of the feedstock by providing the possibility of this treatment at a lower temperature, and in subsequent stages due to the creation of niyu conditions to reduce the volume of redistribution of water in a circular process; PT / RU2015 / 000601

fourteen

in addition, the invention is aimed at reducing losses of reagents and the volume of their replenishment during the implementation of the circular process. Further, when disclosing the essence of the invention and when considering examples illustrating it, other types of technical result achieved can be mentioned.

The proposed method for processing alumina-containing raw materials, as well as the closest known method to it [29], is a circular process, including:

 - stage autopsy, which carry out

 preparation and heating of a reagent solution containing ammonium hydrosulfate,

 decomposition of alumina-containing raw materials with a hot reagent solution to obtain pulp in the form of a solution of aluminum ammonium and other alum together with solid decomposition residues, separation of the pulp into solid and liquid phases to obtain undecomposed solid residues and alum mother liquor;

 - a purification step in which an alum solution purified from iron impurities is obtained;

 - a precipitation stage in which aluminum hydroxide is obtained, precipitated from an alum solution purified from iron impurities by exposure to this solution with ammonia;

 - a step for separating precipitated aluminum hydroxide, in which an intermediate is obtained in the form of said hydroxide, while obtaining a residual solution of ammonium sulfate formed in the precipitation step;

- the stage of obtaining solid ammonium sulfate; - stage thermal decomposition of solid ammonium sulfate, which receive ammonium hydrosulfate and ammonia, used, respectively, at the stage of opening in the preparation of the reagent solution and at the stage of deposition.

To achieve the specified technical result in the method according to the invention, in contrast to the closest known method to it,

 - at the stage of opening during the preparation of the reagent solution, sulfuric acid is added to the latter,

 and the specified separation of the pulp into solid and liquid phases at this stage is carried out with washing solid residues with water,

 in this case, alum mother liquor and washings are separately collected;

 - at the stage of purification from said mother liquor of alum and wash water, at least the latter are purified from iron by the precipitation method, after which these waters and the mother liquor of alum are combined in a heated state and a previously purified mother liquor is obtained,

 then the pre-purified mother liquor is processed in the form of a sequence of operations, including the restoration of the iron contained in this solution to a bivalent state,

 cooling this solution with the release of crystals of aluminum ammonium alum,

separating the latter from the solution and dissolving them in pure water to obtain an alum solution purified from iron impurities, which is sent to the precipitation stage; T / RU2015 / 000601

16

 - in addition, in the specified method, sulfuric acid is extracted from the pre-purified mother liquor obtained at the stage of purification after separation of aluminum-alum crystals from it during said processing,

 why this solution is passed through a column with a strongly basic anion exchange resin in sulfate form,

 wherein the sulfuric acid retained on the anion exchange resin in the indicated column is washed off with clean water and the use of this column is continued, and the extracted sulfuric acid is returned to the head of the process for use in the autopsy stage in the preparation of the reagent solution,

 the processed pre-purified mother liquor, from which the crystals of aluminum-ammonium alum are separated, passed through the indicated column, is combined with the residual ammonium sulfate solution obtained in the separation stage, and then this combined solution is used as the initial product for the production of solid ammonium sulfate .

The processing of the clay-containing raw material by the present invention is not a solution of ammonium hydrogen sulfate and not a mixed solution of a mixture of ammonium hydrosulfate and ammonium sulfate, but a solution of ammonium hydrosulfate with the addition of sulfuric acid leads to a fundamentally new quality of the process: it becomes universal, allowing along with with aluminosilicates (nepheline, kaolin, sillimanite, argillite, ash, etc.) to process difficultly decomposable alumina-containing raw materials, for example, bauxite and even red mud - waste le bauxite processing. one

17

 It should also be noted that, being more effective, the reagent solution according to the proposed method allows the decomposition of easily decomposable raw materials, for example, aluminosilicates such as nefelin, at temperatures lower than those of M. Buchner (up to 75 ° C) .

Theoretically, such an effect could not be assumed, since according to the proposed method, acid is added to the reagent solution in a disproportionately smaller amount than is required by balance for the acid method. This effect is already apparent at an acid concentration of the order of 0.05% or less, including at the level of determination error. It can be assumed that sulfuric acid added to the reagent solution has a catalytic effect. Initially, with an increase in its concentration within a few percent, the process of decomposition of raw materials proceeds with greater intensity, however, in the future, the growth in intensity slows down, and using a concentration of more than 25% is impractical because this does not lead to further acceleration or increase in the degree of decomposition, but complicates the technological process and requires more expensive equipment.

It is sufficient to add sulfuric acid to several weight percent, since this allows to significantly increase the solubility of potassium alum in the hot mother liquor after decomposition and to increase the concentration of ammonium hydrosulfate in the reagent solution to 8.2 mol / l (65% by weight), and this, in turn, it can significantly reduce the amount of water processed into steam in a circular process, and thereby reduce energy consumption. The problem with silicon, which in excess concentration got into the aluminum-containing filtrate after the decomposition of the raw material during the process according to the method of M. Buchner, in the proposed method is solved immediately at the stage of decomposition. When using a reagent solution with the addition of sulfuric acid, silicon almost completely remains in the solid phase - undecomposed residue.

In the proposed method for carrying out the process using a concentrated reagent solution containing several percent sulfuric acid, the problem of iron removal is greatly simplified and it becomes possible to use a low-cost rational scheme. This is due to the fact that under the conditions of application of the proposed method, even with the decomposition of bauxite with almost the same content (by weight) of aluminum and iron, the alum mother liquor obtained after separation of the pulp turns out to be enriched in aluminum by more than an order of magnitude relative to iron. It also turns out that comparable concentrations of aluminum and iron are obtained in wash water, in which there is a substantially smaller portion of the dissolved aluminum compound, therefore, they can be separately processed for preliminary purification of iron, and they are easier to clean from iron than concentrated mother liquor alum solution. In this case, a substantial part of the iron remains in solid residues after decomposition.

Depending on the initial content in the alumina-containing raw materials of alkali and alkaline earth metals and magnesium, forming non-hydrolyzable sulfate salts, in any circular process, including in the process according to M. Buchner, irreversible losses of a certain amount of the main reagent are observed . This is illustrated by the equations of the decomposition reaction of bauxite of a typical molar composition: 0.57Α1 ₂ Ο ₃ · 0.23Fe ₂ O ₃ - (0.12SiO ₂ · 0.05TiO ₂ · 0.01MgO '0.01 ₂ O' 0.005Na ₂ O '0.005CaO)

According to the Buchner method: 0.57A1 ₂ O ₃ · 0.23Fe ₂ O ₃ ^' (0.12SiO ₂ ^" 0.051.02' 0.01 MgO" 0.01K ₂ O '0.005Na ₂ O ¹ 0.005CaO) +

+ 4.86 NH4HSO4 + 17.13H ₂ O =

= 1.14A1NH4 (S0 ₄ ) ₂ i2H ₂ O + 0.46 FeNH ₄ (SO ₄ ) ₂ ^' 12H ₂ O + 1.63 (NH ₄ ) ₂ SO ₄ + 0.12H ₂ SiO ₃ +

+ 0.05TiO ₂ ^' 2H ₂ O + 0,01MgSO ₄ ^' 7H ₂ O + 0,01K ₂ SO ₄ 'H ₂ O + 0,005Na ₂ SO ₄ ¹ I OH ₂ O +

+ 0.005CaSO ₄ 2H ₂ O (1) and by the proposed method:

0.57A1 ₂ O ₃ · 0.23Fe ₂ O ₃ ^' (0.12SiO ₂ ^' 0.05T, O ₂ ^' 0.01MgO · 0.01 ₂ O ¹ 0.005Na ₂ O · 0.005CaO) +

+ 4.8 NH ₄ HS0 ₄ + 17.13H ₂ O + 0.03H ₂ SO ₄ =

-12H₂O + 0,46 FeNH₄(SO₄)₂ '12H₂O + 1,6 (NH₄)₂SO₄ + 0,12H₂SiO₃ +

-12H ₂ O + 0.46 FeNH ₄ (SO ₄ ) ₂ '12H ₂ O + 1.6 (NH ₄ ) ₂ SO ₄ + 0.12H ₂ SiO ₃ +

+ 0.05TiO ₂ · 2H ₂ O + 0.01MgSO ₄ - 7H ₂ O + 0.01K ₂ SO ₄ - H ₂ O +

+ 0.005Na ₂ SO ₄ ^' 10H ₂ O + 0.005CaSO ₄ · 2H ₂ O (2)

Further, the circular process is closed by processes formally described by the reaction equations written below. For both methods:

1.14 AlNH ₄ (SO ₄ ) ₂ -12H ₂ O + 0.46 FeNH ₄ (SO ₄ ) ₂ -12 H ₂ O + 4.8 NH ₃ = 1.14 A1 (OH) ₃ +

+ 0.46 Fe (OH) ₃ + 3,2 (NH ₄ ) ₂ SO ₄ + 19,2 Н ₂ О (3) By the Buchner method: 3.2 (NH ₄ ) ₂ S0 ₄ + 1.63 (NH ₄ ) ₂ SO ₄ = 4.83 (NH ₄ ) ₂ SO ₄ (4)

4.83 (NH ₄ ) ₂ SO ₄ = 4.83 NH ₃ + 4.83 NH4HSO ₄ (5)

By the proposed method:

3.2 (NH ₄ ) ₂ SO ₄ + 1.6 (NH ₄ ) ₂ SO ₄ = 4.8 (NH ₄ ) ₂ S0 ₄ (6)

4.8 (NH ₄ ) ₂ SO ₄ = 4.8 (NH ₄ ) ₂ SO ₄ = 4.8 NH ₃ + 4.8 NH ₄ HSO ₄ (7)

In the first case, in each cycle of the circular process, a little more of the main reagent, ammonium hydrosulfate, is spent than is regenerated; while in the irreversible costs associated with the formation of sodium, potassium, calcium and magnesium sulfates, the reagent is ammonium hydrosulfate, which is more expensive than acid. In the second case, according to the proposed method, the hydrosulfate cycle is completely closed.

In addition, the proposed method completely closes the cycle and ammonia (see equations (3) and (7)). According to the method of M. Buchner, as can be seen from a comparison of equations (3) and (5), in a circular process it is necessary to produce more ammonia than is required. If the ammonia cycle is closed and only 4.8 moles of ammonia are produced per mole of the initial clay-containing raw material, then from cycle to cycle the reagent becomes less and less “acidic” (i.e., less effective) due to the enrichment of the hydrosulphate ammonium admixture of ammonium sulfate.

The proposed method, due to the presence in it of the operation of separating sulfuric acid by passing through a column with a strongly basic anion exchange resin in the sulfate form of an acidic mother liquor obtained during processing at the purification stage after separation of aluminum-ammonium alum crystals from it, allows returning circular 0601

21 processes also sulfuric acid, the excess of which may be contained in solutions after decomposition of alumina-containing raw materials.

The described effects inherent in the proposed method, explain the possibility of overcoming the disadvantages of the method of M. Buchner [29] and achieving a technical result, which is the aim of the invention.

Below, the implementation of the present invention is considered in more detail and with a reflection of the preferred features of the operations, including, in various special cases and depending on the specific conditions of application of the method. When preparing a reagent solution at the stage of opening, it is inappropriate to use a concentration of ammonium hydrosulfate in the reagent solution of less than 5%, since at such a concentration the opening of even easily degradable raw materials is not provided. The preparation of a reagent solution with a content of ammonium hydrosulfate of more than 65% by weight is impractical, since it is difficult to keep alum-potassium alum in the solution after decomposition even at a temperature close to 100 ° C. Alum is precipitated in solid form and falls into the composition of the non-decomposed residue, which leads to loss of aluminum or requires the use of a large amount of washing water; at the same time, a significant part of leached aluminum is contaminated with iron, which is present in wash water in concentrations commensurate with aluminum. All this reduces the profitability of the process.

It is advisable to add sulfuric acid to the reagent solution until its mass concentration reaches from 1 to 5%. As already explained above, within these limits, with increasing concentration, the decomposition of raw materials proceeds with greater intensity. A further increase in one

22

acid retention does not provide a significant increase in the degree of extraction of aluminum, but is associated with additional costs for introducing more acid into the circular process and processing a larger mass of the reagent solution. At the opening stage and further at the cleaning stage, up to the operation of reducing iron to a divalent state (including it), the temperature is maintained in the range of 75-180 ^° C. At a temperature below 75 ° C, aluminum-ammonium alum precipitates, which does not allow correct lead the process. With increasing temperature, the decomposition rate increases, however, an increase in temperature to more than 180 ° C leads to additional costs that are not offset by a decrease in the decomposition time. The choice of temperature determines the hardware design of the method, for example, at temperatures above 100 ° C, autoclave or microwave equipment is used.

Under the conditions described above, the decomposition process can last 2 - ^ - 5 hours.

It is advisable to carry out the operations of cooling a pre-purified mother liquor after iron reduction with the separation of alumina, separating them from the solution and dissolving them in pure water to obtain an alum solution purified from iron impurities at a temperature not exceeding 20 ^° C. At higher temperatures A significant part of the aluminum remains dissolved and does not enter the final product, which makes the processing process uneconomical. In this case, it is preferable, before dissolving in pure water, crystals of aluminum-ammonium alum isolated and separated from the previously purified mother liquor cooled after the reduction operation, to wash these crystals with a concentrated solution of ammonium sulfate cooled to 20 ^° C or lower. This contributes to a deeper cleaning of residual iron.

When these crystals are dissolved in pure water, demineralized water formed at the stage of production of solid ammonium sulfate can be used as the latter. It makes sense to use the ratio of the mass of the reagent solution and the processed raw materials not less than 3: 1. This is due to the fact that for the implementation of an effective decomposition process it is necessary that the mass amount of components of the reagent solution is greater than the total mass amount of raw material components, s which undergo reaction reactions during decomposition. Even if we assume that such raw materials contain alumina with virtually no iron oxide impurities, this ratio should be applied to raw materials containing no more than 15% alumina. Substandard types of raw materials with a lower alumina content would correspond to lower ratios. For the same reason, it makes no sense to apply a ratio greater than 10: 1. Even with a total content of aluminum and iron oxides close to 100%, this ratio already provides an excess of components of the reagent solution in equivalent terms. A further increase in this ratio does not lead to a significant increase in the degree of aluminum extraction, but leads to energy losses associated with the processing (evaporation) of a large amount of water in a circular process. Separation of pulp at the stage of dissection into liquid and solid phases (alum mother liquor and undecomposed solid residues) can be carried out by known methods, such as filtration, centrifugation, decantation, which are equivalent in terms of influencing the possibility of achieving a technical result, which is the aim of the proposed method.

Purification of wash water (or wash water and alum mother liquor) from iron by the precipitation method, carried out at the stage of purification after said separation of the pulp at the opening stage, with washing of solid residues with water and separate collection of the mother liquor of alum and wash water, can be carried out by their ammonization, i.e. adding ammonia to them, and separating the resulting iron hydroxide.

In this case, an increase in the pH of the solution takes place. It is not advisable to increase the pH value to more than 4. This is due to the discovered fact that in real conditions of the process, in accordance with the proposed method, at pH> 4, some of the extracted aluminum begins to lose due to the coprecipitation of its hydroxide with iron hydroxide. The implementation of evaporation simultaneously with an increase in pH increases the efficiency of separation of iron hydroxide from the solution.

It is preferable to carry out the indicated purification from iron in the presence of a polyacrylamide-based flocculant, which contributes to the aggregation of particles and the improvement of their separation. The aforementioned purification of wash water (or alum mother liquor and wash water) from iron is carried out until the ratio of the mass concentrations of aluminum and iron in the preliminary purified mother liquor is at least 10: 1. At lower ratios during the further processing of the previously purified mother liquor the solution must be introduced into it too much reducing agent in relation to the mass of the resulting final product, which makes the process uneconomical.

At the stage of purification during processing of the pre-purified mother liquor, the operation of reducing the iron contained in this solution to a divalent state is carried out using ammonium sulfite or sulfur dioxide or a metal aluminum powder as a reducing agent. The use of such reducing agents is preferable since it does not lead to undesirable formation of components not present in said solution.

Recovery is carried out to prevent the formation of iron-ammonium alum co-crystallizing with aluminum-ammonium alum.

When the ratio in the solution of alum purified from iron impurities obtained by processing the pre-purified mother liquor, the mass concentrations of aluminum and iron is less than 1500: 1, an additional purification of this solution from iron is carried out, which is carried out until the specified ratio is reached or exceeded using the molecular method sorption, or ion exchange, or liquid-phase or solid-phase extraction using sorbents, filaments or extractants with functional groups selective for iron.

This condition is due to the fact that the precipitation of aluminum hydroxide, it is advisable to carry out from a deeply purified solution. It is with this ratio that the content of the iron oxide impurity in alumina is achieved, which will be further obtained from aluminum hydroxide, not more than 0.05%, which corresponds to the standards for metallurgical alumina.

The separation of sulfuric acid from a pre-purified mother liquor obtained at the stage of purification during processing of this solution after separation of aluminum-alum crystals from it is most expedient to be carried out by means of NewChem treatment using, as a column, filled with strongly basic anionite in sulfate form NewKem columns (see below), in which the space not occupied by the indicated ion exchanger is filled with an organic liquid that is not miscible with water and aqueous solutions.

The preparation of solid ammonium sulfate can be carried out, for example, by evaporating a solution obtained by combining the processed pre-purified alum mother liquor passed through a NewCem column with the residual ammonium sulfate solution obtained after separation of the precipitated aluminum hydroxide.

At the same time, desalted condensed water is obtained, which can later be used as pure water for washing off the acid retained on the anion exchange resin in the NewKem column, as well as for dissolving the crystals of aluminum-ammonium alum. ny and separated from the pre-purified mother liquor cooled after the recovery operation.

The proposed method can be supplemented with a stage for producing alumina by dehydration and calcination of an intermediate in the form of aluminum hydroxide obtained in the stage of separation of precipitated aluminum hydroxide.

The above NewKem processing, so named by the authors of the proposed invention (Khamizov, R.Kh., Krachak, AN, Khamizov, S.Kh., Separation of ionic mixtures in columns with two liquid phases, Sorption and chromatographic processes (Sorption and Chromatographic Processes), T.14, j \ ° l, (2014), pp. 14-23 [34]), similar to the one known from RF patent N ° 2434679 (publ. 27.1 1.201 1, [35]), is A variation of the acid retention method: Hatch MJ and Dillon JA, Acid retardation. A simple physical method of separation of strong acids from their salts. I&EC Process Design and Development. 2/4: 253 - 263 (1963) [36].

As applied to sulfate media, its essence lies in the fact that when concentrated solutions of mixtures of sulfates and sulfuric acid are passed through nanoporous sorbents, including gel strongly basic anion exchangers in sulfate form, slightly hydrated molecules and ionic acid vapors are retained in the pores due to their smaller size. , and strongly hydrated ionic pairs of salts pass through a layer of sorbent. The process is carried out in a cyclic mode, each cycle consists of the stages of sorption and desorption. After the acid “slip” at the sorption stage to a certain predetermined level, the desorption of the pure acid retained on the column is carried out simply by water. A limitation of the acid retention method is that for efficient separation acids and salts it is necessary that in the sorption column there was practically no free space between the sorbent granules. To do this, in the standard industrial version of the method, layers strongly squeezed under high pressure are used with “flattened” sorbent granules (US patent _V ° 4,673,507, published June 16, 1987 [37]; Sheedy M, Recoflo ion exchange technology. Proceedings of the TMS Annual Meeting held in 1998 in San Antonio Texas (1998) [38]). However, for mixed colloidal systems and suspensions, which are formed during the processing of iron-containing solutions (when neutralizing the passing solution with acid retention), this approach is not suitable. According to NewCem technology, columns are used in which the sorption layer is completely filled with an organic liquid (for example, decanol, pelargonic acid), which is retained in the column during the processing of mixed solutions containing acids and their salts. Operations with decomposition solutions of alumina-containing raw materials are facilitated, because: a) supersaturated solutions and colloidal systems containing iron compounds are stabilized in New em columns, and precipitation occurs outside of them; b) the transmission of the processed solutions (unlike the standard method of acid retention) is carried out in the direction from top to bottom, and colloidal particles are more easily removed from the column.

The processes of mild hydrolysis with the release of iron hydroxide, as well as with the separation and return of acid in the proposed method, are carried out in accordance with the following reaction equations. They are recorded for all processes occurring during the processing of an acidic mother liquor containing the following components: (NH ₄ ) ₂ SO ₄ , NH ₄ HSO ₄ , FeSO ₄ (after reduction), NH ₄ Fe (S0 ₄ ) ₂ ( residues of iron (III) after reduction), H ₂ S0 ₄ and H ₂ O (residual aluminum in the form sulfate complexes are not mentioned, since aluminum-ammonium alum is not subject to mild hydrolysis on anion exchange resin).

Retention of free acid remaining in the acidic mother liquor sent to the NewKem-treatment (R is the functional group of anion exchange resin):

[R-SO ₄ -H ₂ O] + H ₂ S0 ₄ = [R-SO ₄ -H ₂ S0 ₄ ] + H ₂ 0 (8)

Acid retention during hydrolysis of the residues of the sulfate complex of iron (III) contained in the initial mother liquor with the precipitation of iron hydroxide in the filtrate after the NewKem column: [R-SO ₄ - -H ₂ O] + NH ₄ Fe ( SO ₄ ) ₂ 12H ₂ 0 =

= Fe (OH) ₃ | + NH ₄ HS0 ₄ + [R-SO ₄ - · H ₂ SO ₄ ] + 10 H ₂ O (9)

The acid retention during the hydrolysis of reduced iron sulfate (I) to produce iron hydroxide in the filtrate and its subsequent oxidation with atmospheric oxygen with the precipitation of iron (II) hydroxide in this filtrate:

(10) 2 [R-SO ₄ - · Н ₂ О] + 2FeS0 ₄ + 2Н ₂ О = 2Fe (OH) ₂ + 2 [R-SO ₄ "·

(10)

2Fe (OH) ₂ + H ₂ O + Vg 0 ₂ = 2Fe (OH) ₃ | (eleven)

Flushing (desorption) of a solution of sulfuric acid retained in accordance with reactions (8) - (10) to return it to the head of a circular process: 4 [R-S0 ₄ - H ₂ SO ₄ ] + 4H ₂ 0 = 4 [R-S0 ₄ - H ₂ 0] + 4H ₂ S0 _{4 (12)} The interaction of sulfuric acid with ammonium sulfate in a residual solution aimed at the separation and processing of ammonium sulfate:

4H ₂ SO ₄ + 4 (NH ₄ ) ₂ SO ₄ = 8NH ₄ HS0 _{4 (13)}

The total reaction, taking into account the processes in (8) - (13): H ₂ SO ₄ + NH ₄ Fe (SO ₄ ) ₂ ^' 12H ₂ O + 2FeSO ₄ + 4 (NH ₄ ) ₂ SO ₄ + ^ι Λ0 ₂ =

= 3Fe (OH) ₃ | + 9NH ₄ HSO ₄ + 4H ₂ 0 ₍₁₄₎

Another important effect following from the above reaction equations and used in the proposed method is that the acid returned to the circular process allows the regeneration of ammonium hydrosulfate (under mild conditions, without the use of thermal decomposition) from a substantial part residual ammonium sulfate. The amount of ammonium hydrosulfate is equivalent to the number of iron compounds involved in the process of soft hydrolysis. Finally, the method according to the first proposed invention takes advantage of the conjugation with NewKem acid retention technology, namely, the reduction of ferric iron to a divalent state in the combined solution before precipitation and separation of aluminum-ammonium alum. Such reduction allows one to carry out the processes described by equations (10) and (1 1), during which the probability of deposition of iron (III) hydroxide in the sorption column is significantly reduced. The second proposed invention, related to the method of opening alumina-containing raw materials during processing, is aimed at achieving a technical result, which consists in the possibility of opening any aluminum-containing raw materials without high-temperature (200 ° C and above) processing with an increase in the degree of decomposition and extraction aluminum compounds.

The proposed method for opening alumina-containing raw materials, as well as the closest known opening method according to patents [29] by M. Buchner, involves the preparation and heating of a reagent solution containing ammonium hydrosulfate, the decomposition of alumina-containing raw materials with this solution to obtain pulp in the form of a solution of aluminum-ammonium and other alum together with solid decomposition residues and separation of the pulp into solid and liquid phases to obtain undecomposed solid residues and alum mother liquor.

 To achieve the above technical result in the opening method according to the invention, in contrast to the closest known method, in the preparation of the reagent solution, sulfuric acid is added to the latter, and with the indicated separation of the pulp into solid and liquid phases, they are washed undecomposed solid residues with water and separately collect the alum mother liquor and wash water as solutions for the subsequent extraction of aluminum compounds from them.

The decomposition of the alumina-containing raw material by the invention proposed by the solution of ammonium hydrosulfate with the addition of sulfuric acid leads to the fact that the process becomes universal, allowing, along with aluminosilicates, the opening of difficultly decomposed alumina-containing raw materials, for example, bauxites and even red mud - waste after bauxite processing. Being more effective, the reagent solution according to the proposed method allows to decompose easily decomposable raw materials at lower temperatures, for example, aluminosilicates such as nepheline, i.e. the method becomes universal, and the use of the described techniques when separating the resulting pulp increases, ultimately, the degree of extraction of aluminum compounds.

This effect is already apparent when the acid concentration is about 0.05% or less, including at the level of determination error. Initially, with an increase in its concentration within a few percent, the process of decomposition of raw materials proceeds with greater intensity, however, in the future, the growth in intensity slows down, and using a concentration of more than 25% is inappropriate. this does not lead to further acceleration or increase the degree of decomposition, but complicates the process and requires more expensive equipment.

In the proposed method using a reagent solution containing several percent sulfuric acid, even when decomposing bauxite with almost the same content (by weight) of aluminum and iron, the alum mother liquor obtained after separation of the pulp is enriched in aluminum more than an order of magnitude with respect to iron. It also turns out that commensurate concentrations of aluminum and iron are obtained in the wash water, which, if separated separately, can be processed separately in the future.

In the preparation of the reagent solution, it is impractical to use a concentration of ammonium hydrosulfate in the reagent solution of less than 5%, since at such a concentration practically does not occur once even easily decomposable raw materials, for example, such as nepheline. At the same time, it is not practical to prepare a reagent solution with an ammonium hydrosulfate content of more than 65% by weight, since it is difficult to keep alum-potassium alum in solution after decomposition even at a temperature close to 100 ° C. Alum is released in solid form and falls into the composition of the undecomposed residue, which leads to loss of aluminum.

It is advisable to add sulfuric acid to the reagent solution until its mass concentration reaches from 1 to 5%. As already explained above, within these limits, with an increase in concentration, the process of decomposition of raw materials proceeds with greater intensity. A further increase in the acid content weakly affects the rate of decomposition and is inappropriate, because leads to an increase in its consumption and the need to process a larger mass of reagent solution. In the implementation of the proposed opening method, the temperature is maintained within 75 180 ^° C. At temperatures below 75 ° C, aluminum-ammonium alum precipitates, which does not allow the process to be properly weighted. With an increase in temperature, the decomposition rate increases, however, an increase in temperature by more than 180 ° С leads to additional costs, which are not compensated by a decrease in the decomposition time. The choice of temperature mode determines the instrument design of the method, for example, at temperatures above 100 ° C, autoclave or microwave equipment is used. Under the above conditions, the decomposition takes 2–5 hours. It is preferable to use the ratio of the masses of the reagent solution and the raw material to be opened not less than 3: 1. This is due to the fact that for the implementation of an effective decomposition process it is necessary that the mass amount of the components of the reagent solution is greater than the total mass quantity of the components of the raw material, s which undergo reaction reactions during decomposition. Even assuming that such a feed contains alumina with virtually no impurities of iron oxide, this ratio should be applied to feed with a content of not more than 15% alumina. Substandard types of raw materials with a lower alumina content would correspond to lower ratios. For the same reason, it makes no sense to apply a ratio greater than 10: 1. Even with a total content of aluminum and iron oxides close to 100%, this ratio already provides an excess of components of the reagent solution in equivalent terms. Separation of pulp into liquid and solid phases (alum mother liquor and undecomposed solid residues) can be carried out by known methods, such as filtration, centrifugation, decantation, which are equivalent in terms of influence on the possibility of achieving a technical result, which is the aim of the proposed opening method alumina-containing raw materials.

Brief Description of the Drawings

The invention is illustrated by the diagrams of FIG. 1 to 6 and the following examples.

The circuit shown in several parts in FIG. 1 to 4, shows the sequence and relationship of the operations of the method according to the first of the proposed inventions related to the method of processing gly- nosem-containing raw materials, without the use of signs characterizing this method in particular cases of its implementation.

The circuit shown in two parts in FIG. 5 and FIG. 6 illustrates, in a simplified form, an industrial process for processing alumina-containing raw materials by the same method.

The examples also illustrate a method for processing alumina-containing raw materials in general using a number of features that are preferred in various particular cases of the method, and reflect several possible combinations of such features. The corresponding parts of the above schemes and examples illustrate the method of the second of the proposed inventions, since it is part of the method of the first invention. Thus, the second invention corresponds to FIG. 1, blocks 1 to 3, FIG. 5, p.p. "A", "B" and subparagraph 1 of paragraph "C" of example 1, as well as examples 4, 5, 36 in the part corresponding to the indicated paragraphs of example 1, and the table to examples 6 - 35.

Embodiments of the invention

In the circuit of FIG. 1 - FIG. 4, the features of a method for processing alumina-containing raw materials are graphically presented using formulations, sometimes abbreviated, but close to those that were used above to reveal the essence of this invention. Moreover, distinctive features correspond to blocks with rounded corners. Parts of the circuit of FIG. 1, FIG. 2, FIG. 3, FIG. 4 are labeled A, B, C, D, E, F, G, H, showing how these parts are connected to each other. In the explanations below to the circuit shown in FIG. 5 and FIG. 6, reflecting the industrial process, terms are used that are specific for this purpose of this scheme, aimed at a specialist technologist, and therefore, in some cases, slightly different from the literal names of the stages and operations used to disclose the essence of the present invention. The same reason is due to the sequence of presentation.

Parts of the circuit of FIG. 5, FIG. 6 are labeled K, L, M, N, P, showing how these parts are connected to each other. This diagram shows a closed circular process of processing alumina-containing raw materials, in which part of desalted water obtained at the final stages of the process, namely, at the stage of production of solid ammonium sulfate, is used to prepare the reagent solution (block 8). In addition, wash water is used that is obtained after the separation of aluminum hydroxide from an alum solution purified from iron impurities during its ammonization (block 7; in the diagram they are shown as “wash water 2”).

Solid ammonium hydrosulfate obtained in a circular process after the operation of isolation and thermal decomposition of solid ammonium sulfate is also used to obtain a reagent solution (block 9). In addition, in the preparation of the reagent solution, partially used is the acid returned from the NewKem treatment step (block 1 1), and partly a fresh portion of technical sulfuric acid.

The resulting reagent solution is heated (block 1) and hot mixed with ground alumina-containing raw materials. During decomposition (block 2) for 2 5 hours the mixture is kept hot in an unpressurized (open) reactor or autoclave (depending U2015 / 000601

37 on the type of processed raw materials). The suspension after decomposition is separated (block 3), for example, using filter presses or vacuum filters to obtain a primary hot filtrate (alum mother liquor separated from solid decomposition residues). Then the filters with the indicated residues are washed with hot water (for example, technical softened water) to obtain wash water.

The washings are evaporated and partially ammoniated (block 4) to convert the acidic solution into a slightly acidic solution to precipitate and separate iron hydroxide, for example, by filtration.

The filtration residue (hot) after filtration is combined with the hot primary filtrate to obtain a combined filtrate (pre-purified mother liquor) into which a reducing agent, for example, ammonium sulfite, is introduced (block 5). After reduction, the resulting solution is cooled to crystallize aluminum-ammonium alum, the crystals are separated from the acidic pre-purified mother liquor by filtration (if necessary, washed with a cold concentrated solution of ammonium sulfate, as shown in Example 1 below, but not shown in the diagram here) , then the crystals are dissolved in demineralized water to obtain an alum solution purified from iron impurities, which is briefly called a secondary solution in the scheme (block 6).

The secondary solution is subjected to ammonization (block 7) using ammonia obtained in the last stages of the process by thermal decomposition of the solid ammonium sulfate obtained previously (block 9). In this case, pure aluminum hydroxide is released, which is filtered washed from the residual solution of ammonium sulfate and washed on the filter with demineralized water (block 7).

The washed aluminum hydroxide is sent for drying and calcination (calcination) (block 1 1) to obtain metallurgical alumina. (If necessary, the secondary solution is subjected to deeper purification from iron by sorption or extraction methods; not shown in the diagram).

The acidic mother liquor, from which the alum crystals are separated (block 5), is subjected to NewKem processing (block 10). The sulfuric acid solution obtained in each cycle of this treatment is returned to the head of the process at the stage of preparation of the reagent solution (block 1), and NewChem-filtrate — the solution without acid, is maintained to precipitate iron hydroxide (if necessary, oxidized with atmospheric oxygen, which is not shown in the diagram) ), the indicated hydroxide is separated, and the resulting solution is combined (block 8) with the residual solution of ammonium sulfate.

The combined solution is subjected to evaporation and crystallization of ammonium sulfate (block 8). The condensate of the residue, namely demineralized water, is used at the opening stage during the preparation of the reagent solution (block 1), for dissolving pure aluminum-ammonium alum separated from the mother liquor (block 6), washing the aluminum hydroxide and desorbing (washing off) the acid solution to NewChem processing stages (block 10) (in this case, the brine residue after crystallization is processed with the addition of lime and crystallization of sodium and potassium sulfates, as described in example 1, but not shown in the diagram). The obtained ammonium sulfate is dehydrated, for example, by centrifugation and drying and is subjected to thermal decomposition (block 9) with the release of ammonia used for ammonization (block 7) of the alum solution (secondary solution) purified from iron impurities, as well as ammonium hydrosulfate, sent to the head of the process at the opening stage for the preparation of the reagent solution (block 1). Blocks 1 to 3 in FIG. 5 correspond to the second of the proposed inventions related to the method of opening alumina-containing raw materials, ending with separate collection of the alum mother liquor (“primary filtrate” in the diagram) and washing water when the pulp is separated into liquid and solid phases. Corresponding operations are also presented in FIG. one.

Example 1

 A. Using chemical reagents of qualification “Ch” or industrially produced chemicals of qualification “Techn.”, 200 g of a hot reagent solution (75 ° C) containing 96 g of ammonium hydrosulfate (59.4%), 4.3 g of double aluminum and ammonium sulfate and 1 g of 94% technical sulfuric acid (0.47% pure acid). (In the first production cycle, softened tap water (61.7 ml) is used. In the subsequent cycles, the washing water obtained after washing the intermediate product, aluminum hydroxide in the last stages, is partially used. See below, point “K” .)

B. The reagent solution is poured into the autoclave reactor, to which 26.3 g of Timan bauxite, which has the following composition (wt.%), Are also added:

A1 ₂ O ₃ - 47.7; Fe ₂ O ₃ - 28.3; Si0 ₂ - 8.0; TU ₂ -2.8; K ₂ O - 0.63; MgO - 0.39; Na ₂ O - 0.23; P ₂ O ₅ - 0.22; S0 ₃ - 0.2; CaO - 0, 17; MnO 0.04; Cr ₂ 0 ₃ - 0.04; V ₂ O ₅ - 0.04; loss on ignition (111111), representing mainly water - 1 1.25. Within 3 hours, the suspension is treated in an autoclave at a temperature of 150 ° C;

B. 1) The resulting mixture is subjected to vacuum filtration in a Buchner thermostatic funnel with a water-jet pump at a temperature of 95 ° C. This gives 131 g of the primary filtrate, in which they continue to maintain a temperature of 95 ° C. The filter is washed with 125 g (ml) of hot water with a temperature of 95 ° C. In this case, sediment remains on the filter. The washings are evaporated in a flask with a condenser refrigerator to a residual volume of 60 ml. At the same time, 65 ml (65 g) of condensate are collected, which is left for use in the next cycle.

2) An ammonia solution is added to the residual volume of the washings to pH = 3 (a total of 15 g of a 24% aqueous ammonia solution is added, see item "G"). The suspension obtained is filtered without changing the filter with the precipitate on a Buchner funnel and obtained a combined precipitate (precipitate N ° l) weighing 19.2 g, containing the undissolved part of bauxite, hydrated oxides of iron, titanium, vanadium, chromium and manganese, calcium sulfate (gypsum), and also moisture water. As a result of this procedure, 77 g of the filtrate of treated washings are obtained, which is heated and combined with the primary filtrate, whereby 208 g of a combined filtrate (filtrate N ° l) is obtained.

G. In a hot filtrate N ° l add 2 g of a 15% solution of ammonium sulfite, and the resulting mixture is cooled to 20 ° C. In this case, crystals of aluminum alum precipitate, which are separated from the mother liquor by filtration on a Buchner funnel with a water-jet pump at room temperature. The acidic mother liquor filtrate (filtrate N ° 2, 97 g) is sent to the next processing stage (see next paragraph. "D"). The obtained crystals are washed at a temperature of 20 ° C using 200 g of a 42.1% solution of ammonium sulfate, the washing solution (or filtrate N ° 4, 201, 2 g) is left for use at the appropriate processing stage (see section "E"). Get 1 1 1 g of potassium alum with a moisture content of 20% (88.9 g of pure alum). The resulting alum is mixed with heating (75 ° C) with 58 g of condensate (demineralized) water and an alum solution purified from iron impurities is obtained. 42 g of a 24% ammonia solution are added to this solution (see paragraph "G"). 220 g of a suspension are obtained containing aluminum hydroxide in a solution of ammonium sulfate. The suspension is filtered on a Buchner funnel with a water-jet pump to obtain a filtrate of Ν ° 3 in an amount of 200 g and a precipitate in an amount of 19.13 g containing aluminum hydroxide and moisture (20%). The filtrate N ° 3 is used as a solution for washing crystals of aluminum alum in a subsequent process cycle. The precipitate is processed in the following stages (see paragraph "K").

D. Filtrate N ° 2 (acidic mother liquor) in an amount of 97 g, obtained in accordance with paragraph “G”, is passed through a NewKem column with 45 ml of strongly basic anion exchanger AB-17x8 in sulfate form and with dodecan, filling the free space. The transmission rate is 50 ml / h. A supersaturated neutral solution of iron (II) and (III) hydroxides leaves the column. For a complete transfer through the filtrate, air is blown for 5 minutes using a mini-compressor (for example, for aquariums). The resulting weak suspension is filtered and a wet cake weighing 0.6 g is separated, which is practically pure iron hydroxide. Sludge is sent to discharge or processing. This gives 95.5 g of a filtrate (filtrate N ° 5), which is a concentrated solution 0601

42 a solution of ammonium sulfate mixed with soluble sulfates of magnesium, potassium and sodium. The Ne5 filtrate is stored for use in the following process steps (see next paragraph "E").

E. The filtrates are combined: ΝΞ4 (SM. P. "G") and Ν ° 5 (see "D") and a combined solution of ammonium sulfate is obtained, which is crystallized to wet sand upon evaporation of this solution using a fridge-condenser. The residual brine in the amount of 1.8 g is sucked off on a Buchner funnel with a water-jet pump to obtain wet crystalline ammonium sulfate in an amount of 138 g with a moisture content of 20%. The resulting condensate (demineralized water) in an amount of 1158.3 g is divided into three parts. One part, namely, 57.3 g, is used in the next technological cycle at the stage of deposition of aluminum alum in accordance with paragraph “D”. The second part (66 g) is also used in the subsequent cycle for the preparation of various technological solutions in accordance with pl. “B”, “G”, “G” and “3”, finally, the third part (35 g) is used in the following cycles to prepare the reagent solution.

G. Crystalline ammonium sulfate is dried and calcined at 275 ° C to obtain ammonium bisulfate in an amount of 96 g (mixed with dry aluminum alum in an amount of 4.2 g). The ammonia released in this case is passed through demineralized (condensate) water (52.8 g, starting from the second cycle, returned from the crystallization stage of ammonium sulfate and evaporation in accordance with paragraph "E") and 57 g of a 24% aqueous ammonia solution are obtained , which is used in the subsequent technological cycle at various stages: to bring to a pH = 3 one stripped off solution during the separation of the main part of iron in accordance with paragraph "B" (15 g) and for the precipitation of aluminum hydroxide in accordance with paragraph "G" ( 42 g). 3. After retaining the acid on the NewCem column, as described in paragraph “D”, 6.2 ml (6.2 g) of condensate (or deionized) water are passed in from top to bottom with a flow rate of 20 ml / h. 7.5 g of a 17.1% sulfuric acid solution are obtained, which is sent to the stage of preparation of the reagent solution in the next process cycle in accordance with paragraph "A".

I. In the residual brine (1.8 g) obtained in accordance with paragraph “E”, calcium hydroxide in the amount of 0.4 g in the form of 22.2% of milk of lime (1.8 g) is added. The evolved ammonia (0.2 g) is sent to the stage of preparation of the reagent solution in accordance with paragraph “A” for use in the next process cycle. This gives 3.6 g of suspension, which is evaporated, and the resulting precipitates are sent for discharge or processing. As a result of this operation, 2.6 g of a precipitate of 20% moisture content are obtained, which includes magnesium and aluminum hydroxides, as well as gypsum and potassium and magnesium sulfates.

K. The wet precipitate of aluminum hydroxide (19.13 g) obtained in accordance with paragraph “G” is washed on an ashless paper filter using a Buchner funnel with a vacuum pump and 50 ml of deionized water (or condensate). Wash water (50 g) is stored for use in the next cycle for the preparation of the reagent solution in accordance with paragraph "A" and, in part, to compensate for losses during the evaporation of washing solutions at the stage of washing the precipitate in accordance with paragraph "AT". The washed precipitate, together with a paper filter, is dried in an oven at a temperature of 120 ° C and calcined in a muffle furnace at a temperature of 970 ° C for 2 hours. Obtain 10.02 g of pure aluminum oxide, corresponding to the content of the main components of quality 2015/000601

44

University of metallurgical alumina (GO). At the same time, the through recovery of alumina is 80.01%.

L. Spend the next technological cycle in accordance with paragraph.n. “A” - “K”, except that part of the desalted water (condensate) obtained in the previous cycle in accordance with paragraph “E”, namely, 35 g, is sent to obtain a reagent solution; another part, namely, 66 g, is directed to: washing the precipitate after decomposition of bauxite and filtering (5.3 g, see paragraph "B"); on the preparation of a solution of ammonium sulfite (1.7 g, see p. "G"); on the preparation of an aqueous solution of ammonia (52.8 g, see paragraph "G"); for the desorption of acid from the NewKem column (6.2 g, see "3"). In addition, the washing water obtained in the previous cycle at the stage of washing the intermediate product - aluminum hydroxide in accordance with paragraph "K", namely, 50 g is directed to: washing the precipitate after decomposition of bauxite and filtration (19.7 g , see paragraph "B"); on the preparation of a reagent solution (28.9 g in accordance with paragraph "A"); for the preparation of milk of lime (1.4 g, in accordance with paragraph. And).

M. Conduct subsequent technological cycles in exact accordance with paragraph. "L". Moreover, they achieve a completely closed circular process for the main reagent - ammonium sulfate (and bisulfate). For each cycle 10 g of metallurgical alumina is spent: 2.63 g of bauxite (with an aluminum recovery of 85% at the stage of raw material decomposition and 80% through extraction); 1 g of technical (94%) sulfuric acid; 0.3 g of ammonium sulfite; 0.4 g of technical calcium hydroxide; 1 1.7 ml of softened tap water. Example 2

 The process is carried out in accordance with Example 1, except that in the step described in paragraph "D", 0.15 g of aluminum chips is added to the Nsl filtrate. At the final stage, 7.15 g of pure alumina is obtained, which corresponds to the quality of metallurgical alumina (GO) in the content of the main components. The degree of through extraction of alumina is 75%.

Example 3

 The process is carried out in accordance with Example 1, except that in the step described in paragraph "D", 70 ml (0.2 g) of sulfur dioxide are passed through filtrate N ° l with vigorous stirring.

At the final stage, 7.05 g of pure alumina is obtained, which corresponds to the quality of metallurgical alumina (Г0) in the content of the main components. At the same time, the degree of through extraction of alumina is 74%.

Example 4

 The process is carried out in accordance with example 1 with the exception of the following conditions:

 - prepare 200 g of a reagent solution containing 45% ammonium hydrosulfate and 1% sulfuric acid;

 - 52 g of kaolin clay of the Kaychakskoye deposit having the following composition (wt.%) is used as raw material:

A1 ₂ 0 ₃ - 18.3; Fe ₂ 0 ₃ - 2.7; Si0 ₂ - 64.2; T ₂ -1, 7; ₂ 0 - 2.0; MgO - 0.81; Na ₂ O - 2.1; P ₂ O ₅ - 0.15; CaO - 0.87; MnO - 1.0; RFP - 7.0. - processing of raw materials in the decomposition process is carried out for 5 hours in an open reactor at a temperature of 98 ° C.

 Upon decomposition at the autopsy stage, a degree of recovery is achieved.

82%.

 At the final stage, 7.42 g of pure alumina is obtained, which corresponds to the quality of metallurgical alumina (GOE) in the content of the main components. The degree of through extraction of alumina is 78%.

Example 5

 The process is carried out in accordance with example 1 with the exception of the following conditions:

 - prepare 200 g of a reagent solution containing 45% ammonium hydrosulfate and 3% sulfuric acid;

 - 35 g of nepheline concentrate of the Kola deposit having the following composition (wt.%) is used as raw material:

A1 ₂ O ₃ - 28.0; Fe ₂ O ₃ - 2.4; Si0 ₂ - 44; TU ₂ - 0.55; K ₂ O - 7.6; MgO - 0.45; Na ₂ O - 12.1; P ₂ 0 ₅ - 0.17; CaO - 1, 75; SrO - 0.1 1; MnO - 0.08; RFP - 1.5.

 - processing of raw materials in the decomposition process is carried out for 5 hours in an open reactor at a temperature of 98 ° C;

Upon decomposition at the autopsy stage, a degree of recovery is achieved.

96%

At the final stage, 8.8 g of pure alumina is obtained, which corresponds to the quality of metallurgical alumina (G00) in the content of the main components. The degree of through extraction of alumina is 90%. Examples 6 to 35

 The decomposition of the three types of alumina-containing raw materials mentioned in the previous examples is carried out at different temperatures, but under the same conditions: the hydrosulfate content in the reagent solution is 40%, sulfuric acid 1%; W: T = 10: 1, decomposition time 3 hours. Then, for nepheline concentrate and bauxite, decomposition is carried out under similar conditions, but according to the method of M. Buchner (without adding acid to the reagent solution). Receive data on the degree of extraction of aluminum from raw materials, shown in the table:

From the obtained results it follows that in all cases the proposed methods are significantly more effective than the M. Buchner method as a whole or in part related to the opening of alumina-containing raw materials. Example 36

The process is carried out in accordance with example 1, but with the exception of the following conditions:

 - 200 g of a reagent solution is prepared with a content of 45% ammonium hydrosulfate and 1% sulfuric acid;

 - as raw materials use 35 g of red mud - waste from alumina production having the following composition (wt.%):

A1 ₂ O ₃ - 12.4; Fe ₂ O ₃ - 44.3; Si0 ₂ - 9.3; TU ₂ - 4.4; K ₂ O - 0.1; MgO - 0.93; Na ₂ 0 -2.9; P ₂ O ₅ - 0.75; CaO - 12.3; SrO - 0.1 1; MnO - 0.52; RFP - 7.5.

 - processing of raw materials in the process of decomposition of raw materials is carried out for 3 hours in an autoclave at a temperature of 130 ° C;

 Upon decomposition at the opening stage, an aluminum recovery of 75% is achieved.

 After separation of the pulp and washing in the cleaning step, the following results are obtained:

 - primary filtrate, contains almost 90% of recovered aluminum with a mass ratio of aluminum to iron of 5: 4;

 - wash water, contain iron and aluminum in a ratio of 15: 1. Moreover, the total degree of extraction of iron does not exceed 50%.

 - Silicon, titanium and calcium remain in non-decomposed sediments by more than 95%.

Industrial applicability

The presented description of the invention and examples of the implementation of the proposed methods indicate that they can be successfully applied in the processing of alumina-containing raw materials to obtain metallurgical alumina and related products, and 15 000601

49

also during the opening of alumina-containing raw materials preceding its further processing. The examples also show that the proposed method can even be used for the recycling of waste, namely, red mud. The composition of the washings makes it possible to obtain a mixture of easily decomposing aluminum and iron hydroxides during ammonization, but with a ratio typical for high-quality bauxite, and iron oxide pigments or ore for ferrous metallurgy can be obtained from washings.

Sources of information 1. Liner A.I., Eremin N.I., Liner Yu.A., Pevzner I.Z. Alumina Production, M, Metallurgy, 1978, 394 s.

2. Troitsky I.A., Zheleznoy V.A. Metallurgy of aluminum. - M., Metallurgy, 1977, p. 42-1 16.

3. RF patent JVfe2360865, publ. 07/10/2009. 4. RF patent JV ° 2193525, publ. 27.1 1.2002.

5. Matveev V.A. Physicochemical and technological fundamentals of increasing the efficiency of complex processing of nepheline-containing raw materials by acid methods. Diss. doc tech. Sciences, Apatity, 2009, 299 pp.

6. Isakov EA Pikalevo association "Alumina" in the new conditions. Non-ferrous metals, 1997, N ° 4, p. 8.

7. Vaytner VV Investigation of nitric acid processing of aluminosilicates to obtain alumina. Diss. Cand. tech. Sciences, Yekaterinburg, 2004, 146 p. 8. RF patent J s2202516, publ. 27.1.2002.

9. RF patent JV ° 2215690, publ. 10.1 1.2003.

10. RF patent N ° 2372290, publ. 10.1 01.2009.

11. RF patent JVs2460691, publ. 09/10/2012. 12. Schwartzman B.Kh. Acidic methods of processing alumina-containing raw materials. M.: Tsvetmetinformatsiya, 1964, 82 p.

13. Pustilnik G.L., Pevzner I.Z. Acidic methods of processing low-quality aluminum-containing raw materials. M.: Tsvetmetinformatsiya, 1978, 52 p. 14. Herbert Weissenbaeck, Benedikt Nowak, Dieter Vogl, Horst Krenn,

Development of Chloride Based Metal Extraction Techniques - Advancements and Setbacks, Proceedings of Nickel-Cobalt-Copper Conference of ALTA- 2013, 29 May - 1 June, 2013 Perth, WA., Melbourne, Australia, p. 360.

15. RF patent W ° 2471010, publ. 12/27/2012. 16. Liner Yu.A. Complex processing of aluminum-containing raw materials by acid methods. M .: Nauka, 1982, 208 p.

17. Zapolsky A.K., Sazhin BC, Zakharova N.N. Crystallization of basic aluminum sulfate salts. // Chemistry and technology of alumina. Novosibirsk, Nauka, 1971, p. 430 - 438. 18. Zapolsky AK, Sulfuric acid processing of high-silicon aluminum raw materials. Kiev, Naukova Dumka, 1981, p. 198-200. 19. Paweena Numluk and Aphiruk Chaisena. Sulfuric Acid and Ammonium Sulfate Leaching of Alumina from Lampang Clay // E-Journal of Chemis try. 2012. V 9, No. 3. p. 1364-1372, http://www.ejchem.net.

20. RF patent Ne2337877, publ. 10.1 1.2008.

21. Sandler E.M., Liner Yu.A., Liner A.I., Chizhikov D.M. Decontamination of products using the sulfuric acid method of processing nepheline. Non-ferrous metallurgy. Izv. universities, 1962, 2, p. 30-33.

22. Funaki K. Sulfuric acid process for obtaining pure aluminum oxide from its ores // Bull, of the Tokyo Inst, of Technology, 1980, No. l.

23. RF patent J ° 2440296, publ. 01/20/2012.

24 U.S. Patent N ° 1,426,891, publ. 08/22/1922.

25 USSR Copyright Certificate N ° 42067, publ. 03/31/1935.

26. Ullmann, B. Encyklopadie der technischen Chemie, Auflage, Urban & Schwarzenberg, Miinchen & Berlin. 1954, Bd. 3, 401-420.

27. Grim R.E. Applied Clay Mineralogy, McGraw-Hill, New York, 1962, p. 335-345.

28. G. Bayer, G. Kahr, and M. Mueller-Vonmoos. Reactions of Ammonium Sulphates with kaolinite and other silicate and oxide minerals, Clay Minerals, 1982, V.17, p. 271 - 283.

29. British patent N ° 195,998, published on 04/12/1922; US patent 1,493,320, publ. 05/06/1924; USSR patent l 1489, publ. 09/30/1929. 30. Encyclopedic Dictionary of Named Processes in Chemical Technological / Ed. Alan E. Comyns Boca Raton: CRC Press LLC, 2000, 2-nd Ed., 312 p., P. l9 (Aloton).

31. Bretsznajder St. Otrzymywanie estow kwasu ortokrzemowego w fazie gazovey / St. retsznajder, W. Kawecki // Rocz. Chem, - 1955.- jYa 29. - s. 287-

299.

32. Bretsznajder St. Nova metoda otrzymywania hutniczego tlenku glienovego i innych zwiazkow glinu z glin // Przem. Chem .- 1963.- V. 42, JV ° 12. - s. 677-683. 33. O'Connor, D. J. Alumina Extraction from Non-bauxitic Materials,

Aluminum- Verlag, Diisseldorf, 1988, 159 p.

34. Khamizov, R.Kh., Krachak, AN, hamizov, S.Kh., Separation of ionic mixtures in columns with two liquid phases, Sorption and Chromatographic Processes, T.14, jVel, (2014), S. 14-23.

35. RF patent 2434679, publ. 11/27/2011 1.

36. Hatch MJ and Dillon JA, Acid retardation. A simple physical method of separation of strong acids from their salts. I&EC Process Design and Devel-opment. 2/4: 253-263 (1963). 37. US Patent M> 4,673,507, publ. 06/16/1987.

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39. RF patent Ш 153466, publ. 07/27/2000.

Claims

Claim 1. A method of processing alumina-containing raw materials using a round-robin process, including: an opening step, in which the reagent solution containing ammonium hydrosulfate is prepared and heated, the alumina-containing raw material is decomposed with a hot reagent solution to produce pulp in the form of a solution of aluminum-ammonium and other alum together with solid decomposition residues, separation of the pulp into solid and liquid phases to obtain undecomposed solid residues and alum mother liquor; a purification step in which an alum solution purified from iron impurities is obtained; a precipitation step in which aluminum hydroxide is obtained precipitated from an alum solution purified from iron impurities by exposure to this solution with ammonia; a step for separating precipitated aluminum hydroxide, in which an intermediate is obtained in the form of said hydroxide, while simultaneously obtaining a residual solution of ammonium sulfate formed in the precipitation step; a step for producing solid ammonium sulfate; the stage of thermal decomposition of solid ammonium sulfate, in which ammonium hydrosulfate and ammonia are obtained, which are used, respectively, at the opening stage in the preparation of the reagent solution and at the precipitation stage, characterized in that at the opening stage in the preparation of the reagent solution sulfuric acid is added to the latter, and the separation of pulp at this stage into solid and liquid phases is carried out by washing the non-decomposed solid residues with water, while separately collecting the alum mother liquor and the washing water; at the stage of purification from the said alum mother liquor and wash water, at least the latter are purified from iron by the precipitation method, after which these waters and the alum mother liquor are combined in the heated state and a pre-purified mother liquor is obtained, then processing - a pre-purified mother liquor in the form of a sequence of operations, including restoring the iron contained in this solution to a divalent state, cooling this solution with the release of crystals of aluminum-ammonium alum, separating the latter from the solution and dissolving them in pure water to obtain iron free of impurities alum solution, which is sent to the precipitation stage; in addition, in the said method, sulfuric acid is extracted from the pre-purified mother liquor obtained at the stage of purification after separation of aluminum-ammonium alum crystals from it during the indicated processing, for which this solution is passed through a column with strongly basic anion exchange resin in sulfate form, when In this case, sulfuric acid retained on the anion exchange resin in the specified column is washed off with pure water and the use of this column continues, and the extracted sulfuric acid is returned to the process head for use. the openings during the opening of the reagent solution, the processed pre-purified mother liquor, from which the crystals of aluminum-ammonium alum are separated, passed through the specified column, are combined with the residual solution of ammonium sulfate obtained at the stage of separation of the precipitated aluminum hydroxide, and then at the stage of obtaining solid ammonium sulfate, this combined solution is used as a starting material. 2. The method according to claim 1, characterized in that at the stage of opening, a reagent solution is prepared containing from 5 to 65 weight percent of ammonium hydrosulfate, with the addition of sulfuric acid until its concentration reaches from 1 to 5%. 3. The method according to p. 2, characterized in that the decomposition of alumina-containing raw materials with a hot reagent solution at the stage of opening is carried out when the mass ratio of the reagent solution and alumina-containing raw materials from 3: 1 to 10: 1. 4. The method according to any one of paragraphs. 1 - 3, characterized in that the cleaning of iron by precipitation of wash water or wash water and alum mother liquor, carried out at the stage of purification after the specified separation of the pulp at the stage of opening and washing of these solid residues with water with separate collection of the mother a solution of alum and wash water is carried out by adding ammonia to them and separating the resulting iron hydroxide. 5. The method according to p. 4, characterized in that with the indicated cleaning of iron wash water, the addition of ammonia in them is carried out until a pH of not more than 4 is reached. 6. The method according to p. 5, characterized in that when the specified cleaning of iron wash water additionally carry out their evaporation. 7. The method according to claim 6, characterized in that during said cleaning of the iron from the wash water, iron hydroxide is separated in the presence of a polyacrylamide-based flocculant. 8. The method according to any one of paragraphs. 1 - 3, 5 - 7, characterized in that the cleaning of iron by precipitation of washing water or washing water and alum mother liquor, carried out at the stage of cleaning after the specified separation of the pulp at the stage of opening and washing of these solid residues with separate water by collecting the mother liquor of alum and washings, the ratio of the mass concentrations of aluminum to iron in the pre-purified mother liquor is at least 10: 1. 9. The method according to p. 8, characterized in that at the stage of purification during processing of the pre-purified mother liquor, the operation of restoring the iron contained in this solution to the divalent state is carried out using ammonium sulfite or sulfur dioxide as a reducing agent, or metal aluminum powder. 10. The method according to any one of p. 1 - 3, 5 - 7, 9, characterized in that the processing of alumina-containing raw materials at the stage of opening and further at the stage of purification, up to the operation of reducing iron to a divalent state, including it is carried out at a temperature of 75-180 ^° C. 11. The method according to claim 10, characterized in that in the purification step, the cooling of the previously purified mother liquor after the operation of restoring the iron contained in this solution to a divalent state is carried out to a temperature not exceeding 20 ° C. 12. The method according to p. 1 1, characterized in that the crystals of aluminum-ammonium alum separated from the previously purified mother liquor are dissolved in pure water to obtain an alumina solution purified from iron impurities, and washed with concentrated to a temperature of no higher than 20 ° C ammonium sulfate solution. 13. The method according to claim 12, characterized in that when the said crystals are dissolved in pure water to obtain an alum solution purified from iron impurities, demineralized water formed at the stage of producing solid ammonium sulfate is used as pure water. 14. The method according to any one of paragraphs. 1 - 3, 5 - 7, 9, 1 1 - 13, characterized in that at the stage of purification when the ratio in the resulting solution purified from impurities of iron alum mass concentration of aluminum and iron less than 1500: 1 carry out additional purification of this solution from iron, which is carried out before reaching or exceeding the specified ratio using the method of molecular sorption, or ion exchange, or liquid-phase or solid-phase extraction using sorbents, ion exchangers or extractants with selective for iron functional groups. 15. The method according to any one of paragraphs. 1 - 3, 5 - 7, 9, 1 1 - 13, characterized in that the separation of sulfuric acid from the preliminary purified mother liquor obtained at the stage of purification after separation of the aluminum-ammonium alum crystals from it is carried out by means of NewChem processing using as a column filled with a strongly basic anion exchange resin in sulfate form, a NewKem column in which the space not occupied by the specified anion exchange resin is filled with an organic liquid that is not miscible with water and aqueous solutions. 16. The method according to p. 14, characterized in that the separation of sulfuric acid from the pre-purified mother liquor obtained at the stage of purification after separation of the crystals of aluminum-ammonium alum is carried out by NewChem processing using as a column filled with strongly basic anion exchange resin in sulfate form , NewCem columns, in which the space not occupied by the indicated anion exchange resin is filled with an organic liquid immiscible with water and aqueous solutions. 17. The method according to any one of paragraphs. 1 - 3, 5 - 7, 9, 1 1 - 13, 16, characterized in that as pure water for washing off the sulfuric acid retained on the anion exchange resin when this acid is isolated from the previously purified mother liquor obtained at the stage of purification after separation from it crystals of aluminum ammonium alum, and also as pure water To dissolve these crystals to obtain an alum solution purified from iron impurities, demineralized water formed at the stage of obtaining solid ammonium sulfate is used. 18. The method according to any one of paragraphs. 1 - 3, 5 - 7, 9, 1 1 -13, 16, characterized in that they further dehydrate and calcine the product half in the form of aluminum hydroxide, separated after its precipitation from an alum solution purified from iron impurities, to obtain clay - zema. 19. The method according to claim 17, characterized in that the intermediate product is additionally dehydrated and calcined in the form of aluminum hydroxide separated after its precipitation from the alum solution purified from iron impurities to obtain alumina. 20. A method of opening an alumina-containing raw material during its processing, comprising preparing and heating a reagent solution containing ammonium hydrosulfate, decomposing the alumina-containing raw material with this solution to obtain pulp in the form of a solution of aluminum ammonium and other alum, together with solid decomposition residues, and dividing the pulp into solid and liquid phases to obtain undecomposed solid residues and alum mother liquor, characterized in that in the preparation of the reagent solution sulfuric acid is added to the latter, and when the specified separation of the pulp into solid and liquid phases, the undecomposed solid residues are washed with water and the alum mother liquor and wash water are separately collected as solutions for the subsequent extraction of aluminum compounds from them. 21. The method according to claim 20, characterized in that a reagent solution is prepared containing from 5 to 65 weight percent of ammonium hydrosulfate, with the addition of sulfuric acid until its concentration reaches from 1 to 5%. 22. The method according to p. 20 or p. 21, characterized in that it is carried out at a temperature of 75 ^ 180 ° C. 23. The method according to claim 20 or claim 21, wherein the decomposition of the alumina-containing raw material with a hot reagent solution is carried out at a ratio of 3: 1 to 10: 1 of the mass of the reagent solution and the alumina-containing raw material. 24. The method according to claim 23, characterized in that it is carried out at a temperature of 75-180 ° C.