RU2431601C2 - Method of producing highly pure concentrate from natural quartz - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: quartz is crushed into 15-40 mm chips. Pure quartz is separated from other minerals and contaminated chips. The pure quartz is ground into powder with particle size 0.1-0.4 mm. The powder undergoes magnetic separation and acid treatment in a medium of 10-15% hydrofluoric acid or in a mixture of hydrofluoric acid and hydrochloric acid. The powder is separated from the spent acid, washed with deionised water and dried to moisture content less than 1%. The pure quartz chips are ground without calcination. Gas-liquid inclusions undergo decrepitation via high-frequency electromagnetic exposure. The surfaces of quartz grains are cleaned from remains of technogenic and natural contaminants via attrition of the powder with 5% solution of chloroazotic acid at temperature 80-90°C for 20-30 minutes. The washed and dried powder is then calcined to temperature 1350±10°C and held at that temperature for 5-10 minutes for agglomeration of mineral impurities with quartz sand and sieved. The sieved sand undergoes magnetic separation and chemical cleaning in 10-15% solution of equal volumes of hydrofluoric acid and hydrochloric acid, washed, dried and packed.

EFFECT: invention reduces the number and duration process operations, material and power consumption, provides deep purification of quartz powder, increases purity of production while reducing the environmental load.

2 dwg

Description

The invention relates to methods for purifying natural quartz from mineral and gas-liquid inclusions to obtain high-purity quartz concentrate.

The relevance of developing new methods and technologies for the production of high-purity quartz concentrates used for the needs of modern high-tech industries is indicated by the inclusion of this problem in the list of especially important, priority areas for the development of science and technology in Russia. High-purity quartz concentrate is used for the smelting of very pure quartz glass, used in the most advanced fields of science and technology - this is the production of semiconductors, astronautics, aviation, chemistry of high-purity substances, fiber-optic communications, instrumentation, optical instruments, nuclear industry, medicine, etc. P. The value of such glass is the invariability of its physical and chemical properties over a wide temperature range. It has high optical transparency from infrared to ultraviolet wavelengths, thermal and radiation resistance, and mechanical strength. Another area of use of high-purity quartz concentrate is the synthesis of highly pure polysilicon for the industrial growth of silicon single crystals. They are used mainly in the manufacture of semiconductor devices, devices for converting solar energy into electrical energy, etc. One of the ways to solve the problem of producing high-purity quartz concentrate is to optimize existing and develop new methods for enriching natural quartz raw materials to increase the level of purity of the concentrate and reduce its cost.

A known method of processing quartz-containing raw materials for the production of glass and fiber optics, including crushing, grinding, electromagnetic separation, scrubbing, flotation and heat treatment of the final product, characterized in that the quartz-containing raw materials with a particle size of -60 + 10 mm are subjected to decreation when heated to a temperature of 850-950 ° C followed by rapid cooling in a liquid medium with a temperature of 6-20 ° C, then sent to crushing and grinding to a particle size of -0.5 + 0.1 mm and subjected to electromagnetic separation, then from the non-magnetic part of the separation product and activated water with a pH of 4.0-5.5 prepare the pulp with W: T = 1.8-3: 1, the pulp is rubbed in a medium with a pH of 4.0-5.5 in two stages, between which flotation, while the power of the energy impact in the second stage of the scrubbing is maintained two times lower than in the first, and the temperature in both stages is maintained at the corresponding maximum pulp density to enhance the influential factors of the scrubbing process, after scrubbing the pulp is washed with water at W: T = 10: 1, dehydrated, calcined at a temperature of more than 800 ° C (see RF patent No. 2182113 with priority dated December 4, 2000).

The disadvantage of this method is the need for double scrubbing in a controlled environment with a given temperature and acidity, intermediate flotation, as well as double heating of the purified quartz raw materials. The multiplicity of operations increases the cost of quartz concentrate due to material and energy costs, complicates the enrichment technology due to the need to control their parameters.

There is also known a method for producing high-purity quartz concentrate from natural raw materials developed by the Uralmekhanobr Institute for the Kyshtym mining and processing plant. The method includes an ore preparation cycle and an enrichment cycle of silica powder. The initial quartz is crushed into crushed stone with dimensions of 15-40 mm, washed, pure quartz is separated from other minerals and contaminated crushed stone. Pure crushed stone is ground into a powder of a metric fraction of 0.1-0.4 mm. To facilitate the grinding process of high-strength crushed stone, it is calcined to temperatures of 850-950 ° C and microcracks are created in it by rapid cooling in water, which facilitate subsequent grinding of crushed stone into a powder of a given metric fraction. The mechanical enrichment of quartz is carried out in three stages by alternating the collective flotation of impurity minerals with magnetic separation on polygradient separators. Then the powder is subjected to acid treatment in a medium of 10-15% hydrofluoric acid or in a mixture of hydrofluoric and hydrochloric acids of the above concentration. The ratio of hydrofluoric and hydrochloric acids is 2: 1. After acid treatment quartz separated from the spent acid and washed with deionized water, the acid resistance of the suction filter, and then dried to a moisture content of less than 1% for the drying and the chilling unit vibrated layer pack (see. The book "minerallurgy vein quartz" / Kyshtymsky Mining Plant ; edited by V.G. Kuzmin, B.N. Kravets. - M .: NEDRA, 1990, 294 p.).

The specified technical solution as the closest analogue can be taken as a prototype.

The disadvantage of the prototype is the need for calcining crushed stone to high temperatures and subsequent rapid cooling in water for effective grinding, which requires energy costs and complicates the process. In addition, when calcining rubble, the effect of decrepitation of gas-liquid inclusions (GLC) in quartz is reduced due to the high mechanical strength of the massive individual and an increase in the ductility of quartz.

In the known method for producing quartz concentrate from natural raw materials, flotation purification of quartz powder from mineral inclusions is carried out in chemicals of a given composition for each flotation stage and according to operational procedures. This complicates the cleaning technology, increases its duration, increases the cost of production, is an additional source of pollution of products, production and the environment.

The problem to which the present invention is directed is to increase the purity of the quartz concentrate, simplify the purification technology, reduce the harmful factors of the enrichment process, reduce the cost of the final product by reducing energy and labor costs.

According to the application for the invention, this problem is solved by new modes of operations for cleaning quartz raw materials.

Natural quartz is crushed into crushed stone, washed in water, and pure quartz crushed stone is separated from mineral inclusions and contaminated individuals. Selected crushed stone in the cold state is crushed into powder fractions of 0.1-0.4 mm

Then, for two to three minutes, the powder in a plastic bowl is heated in a microwave at frequencies of resonant vibrations of water molecules of 2.3-2.5 GHz. The liquid coolant boils almost instantly, but the quartz grain remains cold and brittle. As a result, the contents of the GLC of quartz grains is easily opened and can be removed by subsequent cleaning operations. For quartz powders from raw materials of various deposits, the efficiency of microwave decrepitation is higher than thermal by 10-55% (see Nasyrov R.Sh. Microwave decrepitation of gas-liquid inclusions in quartz grains. Ore dressing, St. Petersburg, 2009, No. 2, p. 26-27).

Removal of technogenic and natural ferromagnetic inclusions from the powder is carried out by a single magnetic separation. The surface of quartz grains is cleaned of residues of technogenic and natural mineral and organic contaminants by scrubbing the powder with a 5% solution of "royal vodka" at a temperature of 80-90 ° C for a duration of 20-30 minutes.

The powder washed with clean water to remove traces of the acid solution is dehydrated and calcined to a temperature of 1350 ± 10 ° C and kept at this temperature for 5-10 minutes. Most of the mineral inclusions in the quartz powder and impurities at the boundary between the grains in the bulk and on the surface of the quartz grain have low, on the order of 900-1350 ° C, melting points and can form fusible glasses with quartz (see N.A. Toropov, V.P. Barzakovsky, VV Lapin et al. State diagrams of silicate systems. Handbook, issue 3. Triple silicate systems. L .: Nauka, 448 p., 1972). Refractory mineral inclusions can also form agglomerates with quartz grains due to the formation of eutectic melts in the admixture-quartz contact zone (see Handbook for the Production of Glass, vol. 1, edited by Kitaigorodsky I.I., Silvestrovich S.I. M .: Gosstroyizdat , 1963, 1026 p.). Melts of mineral inclusions or glass phases on the surface of quartz sand contribute to the fusion of neighboring grains of sand, forming agglomerates. Most of them are larger than the upper fractional composition of sand. They are easily removed by sieve screening, which leads to the removal of impurity minerals from silica powder without flotation. Warming up the entire volume of quartz powder to (1350 ± 10) ° С provides additional GREV reduction in quartz individuals. Such heating promotes the polymorphic transformation of α-quartz into tridymite and β-cristobalite, as a result of which GVF can also be opened and impurities can be forced out of the volume of the quartz individual to its surface (see V. Dubinchuk, V. Isaev, N. Oreshnikova, N. G. New Technologies for Processing Opaque Varieties of Quartz (Journal of Exploration and Protection of Subsurface Resources, 1999, No. 3, pp. 24-26). This, in turn, contributes to the agglomeration of mineral inclusions and surface impurities with quartz grains.

High-temperature calcination leads to an increase in the magnetic susceptibility of a number of impurity minerals (see Kobranova V.N. Petrophysics. M: Nedra, 1986, 392 p.). Therefore, quartz powder after calcination and removal of agglomerates is subjected to magnetic separation to remove mineral inclusions and individual small-sized agglomerates with ore inclusions.

After magnetic separation, the quartz powder is purified by chemical etching in a solution of a 10-15% mixture of equal volumes of hydrofluoric and hydrochloric acids at a temperature of (80-90) ° C for (40-60) minutes. During etching, hydrofluoric acid firstly dissolves the vitrified small, not sifted agglomerates, and hydrochloric acid prevents the formation of insoluble salts of impurity minerals and dissolves metallic anthropogenic contaminants, in particular from a magnetic separator. The final operation is washing the powder with high-purity water until the traces of acids are removed, drying the powder and packaging.

The proposed method for producing high-purity concentrate from natural quartz was tested on samples of the Kyshtym deposits of granular quartz and the Zhelannoe deposit. The qualification criterion for the purity of quartz concentrates from these deposits, obtained by the method of the application for the invention and by the prototype method, was the structural and optical quality of vacuum-fused silica glasses from these concentrates. Glasses made of quartz concentrates obtained by the application method had greater optical transparency and fewer defects as compared to concentrates obtained by the traditional method, both in industry and in laboratory conditions.

Figure 1 shows shadow photographs of glass ingots smelted from quartz concentrates obtained from the same quartz sample of core No. 175 of the Kyshtym deposit using the industrial technology method and the method of the claims, and figure 2 shows the optical transmission spectra of these glass ingots in areas of visible and ultraviolet wavelengths. The drawings illustrate the best quality of glasses obtained from quartz concentrates prepared by the method of the claims.

The proposed method for producing high-purity concentrate from natural quartz has the following advantages.

- The method excludes from the enrichment cycle of natural quartz raw materials the operation of calcining quartz gravel, which reduces the number and duration of technological operations, material and energy costs.

- High-frequency electromagnetic decrepitation quickly and efficiently reveals GW in quartz grains, contributing to a more complete cleaning of the powder.

- Powder scrubbing after magnetic separation with a 5% solution of “royal vodka” cleans it of surface technogenic contaminants, products uncovered by GW, oxide and organic contaminants.

- Calcining of quartz powder, removal of agglomerates from it, subsequent magnetic separation, eliminates the flotation operation from the cleaning technology. This reduces the number of technological operations, the duration of the enrichment process, reduces energy costs, increases the purity of production, reduces the environmental burden on the environment.

- Chemical etching of silica powder in an acid solution at the final stage of purification ensures its deep cleaning.

Claims (1)

A method of obtaining a high-purity concentrate from natural quartz, which consists in the fact that quartz is crushed into crushed stone with dimensions of 15-40 mm, pure quartz is separated from other minerals and contaminated crushed stone, crushed into a powder of a metric fraction of 0.1-0.4 mm, magnetic separation is carried out powder, it is subjected to acid treatment in a medium of 10-15% hydrofluoric acid or in a mixture of hydrofluoric and hydrochloric acids of the above concentration, the powder is separated from the spent acid and washed with deionized water, dried to a moisture content of less than 1%, different m, pure quartz gravel milled without calcination, is subjected to gas-liquid inclusions decrepitation rf electromagnetic influence, after magnetic separation quartz powder cleans the surface of quartz grains of residues of natural and man-made mineral and organic contaminants attrition powder 5% solution of "aqua regia" at 80-90 ° C for 20-30 minutes, then the washed and dehydrated powder is calcined to a temperature of (1350 ± 10) ° C and kept at this temperature for 5-10 minutes for agglomerate tion of mineral admixtures with quartz sand, sieved through a sieve with mesh equal to the high value powder fraction to remove agglomerates carried out magnetic separation and chemical purification of sifted sand 10-15% solution of equal volumes of hydrofluoric and hydrochloric acids, washed, dried and pack.

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