RU2393252C1 - Procedure for production of tin out of kassiterit concentrate - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: procedure consists in preparing charge by mixing concentrate with carbon at weight ratio 1:(0.2-0.25) and with fluxing additives. Also mixture of sodium carbonate and sodium chloride are used as fluxing additives at weight ratio of concentrate: carbon: sodium chloride: sodium carbonate equal to 1:(0.2-0.25):(0.12-0.15):(0.12-0.15). Reduction melting of produced charge is performed at temperature 850-870°C during 1.5 hours.

EFFECT: reduced temperature of melting at sufficiently complete extraction of tin out of concentrate.

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Description

The invention relates to the metallurgy of rare and non-ferrous metals, in particular for the production of tin from cassiterite concentrates.

Currently, various methods for producing tin from mineral tin concentrates are known. Alkaline melting of the initial tin concentrate at ~ 800 ° C is used to transfer tin into the solution and its subsequent isolation from the solution [1]. A known method for the extraction of tin by sulfidation of cassiterite with sodium sulfate and aqueous leaching of melt with the transfer of tin thiosols in solution [2]. Known hydrometallurgical methods include a multi-stage technological scheme for processing mineral concentrates, including facilities for wastewater treatment.

Methods based on the conversion of tin to sublimates in the form of chlorides using chlorine salts, for example CaCl ₂ or chlorine gas, are very common [3].

The disadvantages of the known sublimation methods include the use of sophisticated equipment and the corrosiveness of the medium at high process temperatures.

The most widely used is the method of carbon thermal reduction of mineral concentrates, in which the tin concentrate is fired to remove sulfur and arsenic. The calcined concentrate is treated with an acid solution (HCl) to transfer soluble impurity elements to the solution. The concentrate prepared for melting is mixed with coal and fluxing additives (CaCO ₃ , SiO ₂ ). The resulting mixture is melted in furnaces at a temperature of 850-1300 ° C, where SnO _{2 is} reduced by coal for ~ 10 hours. The result is a rough tin with a content of the main component of 50-93% wt. depending on its content in concentrate.

The disadvantages of the method are the complicated technological scheme, incomplete extraction of tin, high operating costs [4].

The closest analogue to the proposed technological essence and the achieved result is a method for producing tin from cassiterite concentrate [5]. According to the known method, the process is carried out by preparing the mixture by mixing tin concentrate with coal, fluxing additives and subsequent melting of the mixture at 850-1000 ° C. As fluxing additives, sodium carbonate and sodium nitrate are used with a mass ratio of concentrate: coal: sodium carbonate: sodium nitrate equal to 1: (0.2-0.25) :( 0.12-0.15) :( 0.6 -0.8), melting is carried out for two hours.

The disadvantage of this method is the relatively high temperature (~ 1000 ° C) of the melt.

The technical problem to which the invention is directed is to reduce the melting temperature with a sufficiently complete extraction of tin from the concentrate.

The problem is solved in that in the proposed method for producing tin from cassiterite concentrate, including the preparation of a mixture by mixing tin concentrate with coal, fluxing additives containing sodium carbonate, melting the mixture at 850-870 ° C, cooling the melt, separating the metal from slag, according to the invention as a fluxing agent in the preparation of the mixture using a mixture of sodium chloride and sodium carbonate in a mass ratio of concentrate: coal: sodium chloride: sodium carbonate, equal to 1: (0.2-0.25) :( 0.12-0.15): (0.12-0.15), pl taste lead within 1.5 hours.

The advantage of the proposed technological solution is as follows:

- the use of salt melts of NaCl, Na ₂ CO ₃ in a predetermined ratio to the concentrate allows the process to be carried out at a lower temperature compared to the known method (870 ° C) and provides a high degree of extraction of tin in the rough alloy (95-97%);

- the use of salt melts of NaCl, Na ₂ CO ₃ creates the conditions for slagging a significant part of impurity elements (for example, iron).

Method implementation examples

1. A portion of cassiterite concentrate (~ 40% SnO ₂ ) is mixed with reagents in the ratio: 0.2 wt. Per one mass fraction of concentrate. fractions of coal, 0.12 wt. fractions of sodium chloride, 0.12 wt. fractions of sodium carbonate. The prepared mixture is melted in an oven at ~ 850 ° C for 1.5 hours. At the end of melting, the melt is poured into the mold, cooled, the hardened metal is separated from the slag. The output of tin in the rough alloy is 95%.

2. A portion of cassiterite concentrate (~ 40% SnO ₂ ) is mixed with the components of the mixture similar to the example described above: 0.25 wt. fractions of coal, 0.15 wt. fractions of sodium chloride, 0.15 wt. fractions of sodium carbonate. The prepared mixture is melted in an oven at ~ 870 ° C for 1.5 hours. At the end of melting, the melt is poured into the mold, cooled, the hardened metal is separated from the slag. The output of tin in the rough alloy is 97%.

Information sources

1. Murach N.N., Sevryukov N.N. Tin metallurgy. M .: Metallurgy, 1964, 351 p.

2. Kolodin S.N. Secondary tin and processing of poor tin raw materials. M .: Metallurgy. 1970, 249 p.

3. Sevryukov N.N. Metallurgy and technology of non-ferrous metals. M .: Metallurgy, 1984.

4. Belyaev D.V. Tin metallurgy. M .: Metallurgizdat. 1960, 370 p.

5. Patent for invention No. 2333268 "A method for producing tin from cassiterite concentrate." Published September 10, 2008. Bull. Number 25.

Claims (1)

A method of producing tin from cassiterite concentrate with a content of approximately 40 wt.% SnО ₂ , including the preparation of a mixture by mixing the concentrate with coal in a mass ratio of 1: (0.2-0.25), fluxing additives containing sodium carbonate, reducing charge melting at a temperature 850-870 ° C, cooling the obtained melt and separating the metal from the slag, characterized in that in the preparation of the charge, a mixture of sodium carbonate and sodium chloride is used as fluxing agents in a weight ratio of concentrate: coal: chloride to dence: sodium carbonate = 1: (0.2-0.25) :( 0.12-0.15) :( 0.12-0.15), reducing melt was reacted for 1.5 hours.