RU2436855C1 - Procedure for extraction of aluminium and iron from ash-and-slag waste - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: procedure for extraction of aluminium and iron from ash-and-slag waste consists in treatment with solution of sulphuric acid and in extraction of aluminium containing components into solution. Before extraction of aluminium containing components into solution waste is subjected to classification and multi-stage magnetic separation at periodic increase of field of magnetic induction for complete extraction of magnetic fraction containing iron.

EFFECT: raised efficiency of extraction of aluminium and iron from ash-and-slag material, reduced expenditures for reagent treatment of material.

1 dwg, 2 tbl

Description

The invention relates to the field of mineral processing and can be used in the processing of ash and slag waste, industrial raw materials containing iron and aluminum.

A known method of producing aluminum sulfate, including the formation of pulp from the feedstock in the form of slag of aluminum production containing aluminum oxide, by mixing the feedstock with water, the interaction of the components of the slag with sulfuric acid and water to form an aqueous solution of aluminum sulfate [1].

The disadvantage of this method is the use for extraction of a highly concentrated solution of sulfuric acid (70-75%).

A known method of producing aluminum sulfate, including pre-washing the slag containing aluminum oxide from salts, then treating it with sulfuric acid, filtering the resulting solution from sand [2].

This method does not provide effective preparation of aluminum-containing raw materials. The disadvantage is the limited raw material base for the application of the method when using dump aluminum-containing slags, while ASW are widespread raw materials.

Closest to the proposed method is a method for producing a coagulant by dissolving iron and aluminum oxides from clay or ash with sulfuric acid with the addition of sodium chloride. The process is carried out with heating and transmission of direct or alternating electric current [3].

The disadvantage of this method is the use of an electrolysis process, as a result of which an alkali is formed, which neutralizes acid during the extraction process. This reduces the recovery rate of the components.

The technical result is to increase the efficiency of extraction of aluminum and iron during extraction from ash and slag material, reducing the cost of reagent processing of the material.

The technical result is achieved by the fact that in the method for extracting aluminum and iron from ash and slag waste, including processing a solution of sulfuric acid with extraction of aluminum-containing components into a solution, before extracting aluminum-containing components into a solution, the waste is subjected to classification and multi-stage magnetic separation with a periodic increase in the magnetic induction field to completely separate magnetic fraction containing iron, and the extraction of aluminum-containing components is carried out from a non-magnetic fraction first and treatment with a 60-85% solution of orthophosphoric acid for 3 hours at a temperature of 100-120 ° C, followed by filtration and then treatment of the precipitate with a solution of sulfuric acid, while processing is carried out with a 30% solution of sulfuric acid.

The combination of new essential features allows us to solve a new technical problem for the extraction of aluminum and iron-containing components from ash and slag waste.

The drawing is a diagram of the extraction of aluminum and iron-containing components of ash and slag waste using magnetic separation and acid extraction.

The implementation of the method was carried out as follows.

Ash and slag material containing valuable components (table 1) was crushed and classified to a particle size of -2.0 + 0.0 mm and subjected to a magnetic separation process to separate the magnetic fraction containing iron and other heavy metals.

Table 1 Silicate analysis of feedstock Sample number The content of the determined component,% SiO ₂ TiO ₂ Al ₂ O ₃ Fe ₂ About ₃ MnO MgO Cao Na ₂ O K ₂ O P ₂ O ₅ SO ₃ Loss on ignition one 57.05 0.53 22.19 9.1 0.2 1,63 2.28 0.85 2.11 0.21 0.28 3.38 2 59.62 0.49 21.29 11.32 0.28 1.27 1.99 0.81 2.06 0.2 0.14 0.95 3 60.0 0.68 24.76 5.33 0,07 1.84 3.20 0.70 2.11 0.22 0.1 0.5 four 58.57 0.57 20.97 10.66 0.21 1.73 3.20 0.74 2.0 0.26 0.17 0.73 5 59.57 0.59 22.27 8.66 0.15 1.55 2.91 0.64 1.3 0.25 0.1 0.5

The process was carried out in several stages (3-5 cleanings) with an increase in the magnetic induction field in cleaning operations to increase the degree of extraction of the magnetic fraction. The technological parameters of the separation process are shown in table 2.

table 2 Summary table of magnetic fraction enrichment products. Product Exit % Magnetic fraction 4.91 Intermediate product 8.31 Tails 86.48 Carbonaceous 0.3 Total 100.00

The non-magnetic fraction (magnetic separation tails) was subjected to two stage extraction with solutions of phosphoric and sulfuric acids. At the first stage, the treatment was carried out with a 60-85% phosphoric acid solution, which increased the yield of aluminum-containing components from the glassy phase of the ash and slag material. By varying the temperature, reaction time and acid concentration, by analyzing the obtained data, the conditions of the aluminum extraction process are revealed, at which the extraction is greatest at a time of 3 hours and a temperature of 100-120 ° C. After the extraction time has elapsed, the precipitate is separated from the mother liquor by filtration. The mother liquor, separated from the aluminum-containing components, is returned to the technological cycle of processing the source material of ash and slag waste.

In the second stage, the precipitate is treated with a 20-30% sulfuric acid solution. The solution of the aluminum-containing component is separated from the silicate component by filtration. The determination of the amount of aluminum was carried out by the photometric method with aluminone according to GOST 18165-89 [4], the determination of iron by titration with potassium thiocyanate.

The implementation of the method allowed to achieve 60-65% recovery of aluminum-containing components. The two-stage extraction process allows to increase the selectivity of the extraction of aluminum-containing components, due to the different solubility of phosphates of the main ash components in acids. The extraction process conditions do not require the use of a special type of equipment. The process can be carried out without the use of an autoclave in an acid-resistant stirred reactor. The widespread use of the method will provide economic and environmental efficiency due to the disposal of widespread waste heat.

Information sources

1. Patent No. 2220098 of the Russian Federation. A method of producing aluminum sulfate / Akimov I.Ya., Ermakov M.V., Melnikov G.M., Parakhin Yu.A.

2. Patent No. 2315715 of the Russian Federation. A method of producing aluminum sulfate / Zakharevsky V.N., Imangulov R.R.

3. Patent No. 2122975 of the Russian Federation. A method of obtaining a coagulant / Khanin A.B., Ivanov A.D., Budykina T.A.

4. GOST 18165-89 “Drinking water. Method for determination of mass concentration of aluminum. "

Claims (1)

A method for extracting aluminum and iron from ash and slag waste, comprising treating a solution of sulfuric acid with extraction of aluminum-containing components into a solution, characterized in that prior to the extraction of aluminum-containing components into the solution, the waste is subjected to classification and multi-stage magnetic separation with a periodic increase in the magnetic induction field to completely isolate the magnetic fraction, containing iron, and the extraction of aluminum-containing components is carried out from the non-magnetic fraction by first processing with 60-85% rast Hur orthophosphoric acid for 3 hours at a temperature of 100-120 ° C, followed by filtration and then treating the precipitate with sulfuric acid, wherein the treatment is carried out with 30% sulfuric acid solution.

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