RU2198023C1 - Method of chemical processing of mineral concentrates - Google Patents

Abstract

FIELD: chemical technology. SUBSTANCE: method includes successive reaction of mineral concentrates with reagent forming azeotropic mixture with water, and flushing water in reactors into which concentrate is preliminarily loaded, and successively supplied reagent and flushing water of required purification degree. Used solutions are separated into impurity elements, reagent and water with their simultaneous purification. After that, purified reagent and water are separately returned to reactor. EFFECT: reduced consumption of deionized water, reagent and requirements to reagent quality, decreased volumes of discharged solutions in conduction of chemical processing of mineral concentrates. 2 dwg, 1 tbl

Description

 The invention relates to the field of chemical technology and can be used for chemical enrichment of mineral concentrates.

 The enrichment of mineral concentrates can significantly improve the technical and economic indicators of production, provided the development of environmentally friendly and cheap enrichment technology.

 Known traditional methods of enrichment (sorting, separation, flotation) [1-4]. However, they do not allow for deep cleaning to obtain high-quality mineral raw materials. The reasons for the insufficient purification of mineral concentrates are the presence on the surface of the minerals of film contaminants, impurity grains with similar physical properties (magnetic properties, density, wettability, etc.), intergrowths with other minerals and structural contaminants that are relatively evenly distributed in the volume of the crystals. Obviously, with a small proportion of structural impurities after physical enrichment methods, the use of chemical treatment as a finish treatment can significantly improve the quality of concentrates.

The main requirements for the process of chemical enrichment of mineral raw materials are:
- the use of such reagents that make it possible to transfer insoluble impurities into the solution (strong mineral acids are most often used for this purpose);
- the solubility of the basic substance in the selected reagent should be significantly less than the solubility of impurities in it;
- the use of reagents and wash water of the required degree of purification to prevent the introduction of additional impurities with them;
- minimizing the environmental burden on the environment.

 Fulfillment of the above conditions is associated with the need to use expensive chemical reagents of the brand “special part”, deionized water and a complex of neutralization and wastewater treatment. It should be noted that after 1-5 cycles of use, a complete replacement of reagents (acids) is necessary. The combination of these requirements makes the chemical enrichment of mineral concentrates an expensive redistribution.

A known method of cleaning grains of quartz sand (silicon dioxide) from impurities [5], which consists in the fact that quartz sand is fed into a stream of hot hydrogen-containing gas (hydrogen and oxygen), to which halogens (chlorine) or halogen-containing substances are formed, forming volatile pollutants compounds that are removed by burning gas at a temperature of from 1600 to 2000 ^o C, after which sand is released from the gas stream in a cyclone precipitator. This method is used for purification from alkali and alkaline earth metals. Obviously, this method is fire and explosion hazard, requires a fairly complex main and auxiliary equipment and structural materials that do not introduce additional impurities during the implementation of the process.

 The closest technical solution to the claimed combination of essential features is a method of enrichment of quartz grains [6], the technological scheme of which is shown in figure 1.

In chemical reactors, chemical enrichment of quartz grains occurs in a mixture of concentrated hydrofluoric and hydrochloric acids in a volume ratio of 1: 0.85. As a result of the exothermic reaction of hydrofluoric acid with quartz grains, the liquid phase is heated to the boiling point. The resulting vapor phase displaces the washing solution from the first to the second reactor. Further, the processing of quartz raw materials in the first reactor proceeds in an atmosphere of acid vapor. After holding for 30-40 minutes, the quartz grains from the first reactor are washed with deionized water and fresh grains are loaded. Fresh acid solution is added to the second reactor to the required volume, and the chemical enrichment process is repeated similarly to the process carried out in the first reactor. As a result, it is possible to reduce the total impurity content in quartz grains to a level of 1 • 10 ^-4 % to 5 • 10 ^-4 % (the initial content of impurities ranges from 5 • 10 ^-4 % to 50 • 10 ^-4 %). The consumption rates of hydrofluoric and hydrochloric acids are 100 and 80 kg, respectively, per 1 ton of grains.

The disadvantages of this method are:
- the use of expensive reagents, namely acids of the brand "os. h." and deionized water;
- irretrievable losses of partially spent reagents;
- the need to use large volumes of deionized water to wash the grains from acids;
- the need for treatment of waste wash water before discharge into the environment;
- large energy costs associated with obtaining deionized water in large volumes.

 An object of the invention is to reduce the consumption of deionized water, reagents, reducing the quality requirements of reagents and reducing the volume of waste solutions during the chemical enrichment of mineral concentrates.

 The problem is achieved in that in the method of chemical enrichment of mineral concentrates, including the sequential interaction of mineral concentrates with a reagent, forming an azeotropic mixture with water, and washing water in reactors, which in turn supply the reagent and washing water of the required degree of purification, the spent solutions are divided into impurity elements, reagent and water with their simultaneous purification and separately return the purified reagent and water to the reactors. This method allows the use of low-quality reagents for enrichment and washing the concentrate from the reagent directly in the reactor, and additional washing of the processed mineral concentrate discharged from the reactor is not required. Thus, the closed cycle of the chemical enrichment of mineral concentrates in the aqueous phase is ensured, which significantly reduces the volume of liquid waste.

 The inventive step of the method consists in the separate return of the reagent and water of a sufficient degree of purification to the reactors for purification of mineral concentrates after separation of the spent solutions into impurity elements, reagent and water with their simultaneous purification.

 The method is illustrated by the technological scheme of enrichment of mineral concentrates (figure 2) and an example of its implementation.

 Example.

 To implement the proposed method, quartz grains were used as a mineral concentrate, an evaporator cube was used as an impurity concentrator, and a distillation column was used as an apparatus for separating and purifying reagent and water. The distillation column was brought to an operating mode in which an aqueous solution of hydrofluoric acid with a concentration lower than that in the azeotropic mixture by 20-60% was boiling in the evaporator cube. The reflux ratio was in the range from 1 to 0.2. In the operating mode of the installation from the column, a constant selection of acid from the lower plates (from the second, third or fourth) was carried out. Purified water was taken from the top plate of the column (the column design and the number of plates should provide a pH of more than 4 in the indicated range of acid concentrations and reflux ratio). Through the switching device, hydrofluoric acid was supplied to the first reactor, and washing water to the second. The third reactor, previously unloaded from the washed quartz grains, was loaded with fresh portions of the original quartz grains.

 After reaching a pH of more than 3 at the outlet of the second reactor, a switching device was switched. As a result of the switch, the acid solution entered the third reactor, water into the first, and the cleaned grain was unloaded from the second reactor and a fresh portion of the grain was loaded, etc. The spent acid and water entered the impurity concentrator (cube-evaporator), the aqueous phase from which was sent to the apparatus for the separation and purification of acid and water (distillation column). After separation and purification, water (pH≥4.0) and hydrofluoric acid (mass fraction from 1 to 10%) were dosed with the required degree of purity into a switching device.

 Depending on the task, the process is easily optimized, regulated and automated using available technical means.

 Comparative characteristics of the prototype and the proposed method are presented in the table.

 The results presented in the table indicate that the claimed method significantly improves the performance of the process without compromising the quality of the final product.

 The technical result consists in reducing the consumption of deionized water, hydrofluoric acid, lowering the requirements for the quality of hydrofluoric acid and in reducing the volume of effluent solutions during the chemical enrichment of quartz grains, which reduces economic costs and reduces the environmental load on the environment.

Literature
1. Barsky M.D., Revnivtsev V.I., Sokolov Yu.V. Gravitational classification of granular materials.- M .: Nedra, 1974.

 2. Vicksman E.S., Chaplinsky A.D., Schneider D.N. Classification of abrasive materials in an electrostatic separator with mesh electrodes. In the book: Improving the processes of electric separation and the design of electric separators. L., 1987.

 3. Zadorozhny V.K. Flotation of feldspathic quartz ores in a water cycle. Series "Ore dressing and the problem of non-waste technology." L .: Science, 1980.

 4. Kravets B.N. Special and combined enrichment methods. -M .: Nedra, 1986.

5. Verfahren fur die Reinigung von SiO ₂ - Kernung und Vorrihtung zur Durchfuhrung des Verfahrens: Application 19813871, Germany. IPC C 01 B 33/12. Dobrat M.; Heraens Quarsglas Gmbh & Co. KG. - 18813971; claimed March 24, 1998; Publ. 07.10.1989.

 6. Kuzmin V. G., Kravets B. N. Mineralurgy of vein quartz. M .: Nedra, 1990, p.206 (prototype).

Claims (1)

 The method of chemical enrichment of mineral concentrates, including the sequential interaction of mineral concentrates with a reagent forming an azeotropic mixture with water, and washing water in reactors that pre-load the concentrate, alternately supplying the reagent and washing water of the required degree of purification, characterized in that the spent solutions are divided into impurity elements, reagent and water with their simultaneous purification and separately return the purified reagent and water to the reactors.

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