RU2375481C1 - Method for extraction of germanium - Google Patents

Abstract

FIELD: technological processes.

SUBSTANCE: invention is related to method for extraction of germanium from germanium-containing material. Method includes preparation of charge by mixing of germanium-containing material, sulphidiser and reducer, moistening of produced mixture, sintering and melting in electric furnace with maintenance of charge layer on melt surface with thickness of 0.1÷0.3 m. At the same time preparation of charge is carried out with application of mixture of flue ash and carry-overs from combustion of germanium-containing carbonaceous raw materials as germanium-containing material. Prior to moistening, charge is crushed down to size of not more than 0.4 mm. Sintering is done by briquetting to the moisture of 12÷18%, and sintered charge prior to melting is maintained for 7÷8 hr. Sintered charge prior to melting is dried at the temperature of 70÷120°C and disseminated with extraction of fraction minus 5 mm with its return for crushing.

EFFECT: increased extraction of germanium with improved efficiency of electric furnace and reduced electric energy consumption.

3 cl, 2 tbl, 4 ex

Description

The invention relates to the field of metallurgy of dispersed metals, mainly to the field of processing of germanium-containing raw materials, in particular products of the combustion of germanium-containing coals, to obtain enriched germanium sublimates by electric melting.

When processing germanium-containing coals and carbonaceous rocks (mudstones, siltstones) by burning in layered and cyclone furnaces, as well as in fluidized-bed furnaces during gas purification in cyclones and bag filters, coarse dust (fly ash) and fly ash (sublimates), respectively, are emitted by dry method, enriched with germanium. In this case, the dust-gas mixture preliminarily passes through the radiation and convection parts of the boilers for heat recovery to produce steam or hot water. The components of gangue, included in the ash part of the raw material, are concentrated in solid (bed burning and fluidized bed burning) or liquid (in cyclone burning) slag. The most common method of coal flaring for germanium raw materials is not applicable, since it is accompanied by a high mechanical ablation of ash components and an insufficiently high degree of enrichment of the captured dust with germanium. Of the combustion methods used for germanium-containing coals, stratified differs in the highest degree of enrichment of captured dust.

For the processing of fly ash and fly ash from coal combustion, chemical and metallurgical methods are used to ensure the production of standard germanium concentrates (from 5 to 50% germanium), which are subsequently sent to produce tetrachloride, germanium dioxide and high-purity metal. Of the known methods, metallurgical methods are most effective (see Shpirt, M.Ya. Physicochemical fundamentals of processing germanium raw materials. M: Metallurgy, 1977, 194 pp.), Based on the sublimation of germanium monosulfide in heat treatment by firing and smelting.

A known method for the extraction of germanium with its transfer to sublimates, including the melting of germanium-containing materials in an open (for example, a baking oven) or closed (for example, in a crucible furnace) melting zone, which is carried out in the presence of slag-forming components (fluxes) and sulfur, the amount of which is in the range of 5% less and 10% more (by weight of the mixture) of the minimum necessary to obtain a homogeneous melt without highlighting layers of metal or speys (US patent No. 2889196, CL 23-17, 1959).

The disadvantages of this method — the low degree of enrichment of sublimates and the degree of extraction of germanium — are due to incomplete sulfidation and reduction of germanium compounds, since inactive elemental sulfur is used as a reducing agent. The recovery of sublimates is carried out from the melt, which significantly increases the duration of the process and leads to the contamination of sublimates with harmful impurities, in particular arsenic and sulfide sulfur.

The closest analogue of the invention is a method for the extraction of germanium according to patent RU No. 2058409 C1, IPC ⁷ C22B 41/00, authors I.N. Tanutrov, O.I. Podkopaev, M.N. from germanium-containing material, a sulfidizing agent and a reducing agent. Before melting, the initial mixture is moistened to a moisture content of 25 ÷ 30%. Melting is carried out while maintaining on the melt surface a charge layer with a thickness of 0.1 ÷ 0.3 m when it is heated at a rate of 5 ÷ 20 ° C / min. The amount of sulfur in the initial charge is supported by 3 ÷ 8%.

The use of the closest analogue is effective in the processing of dispersed germanium-containing materials, such as fly ash from coal burning by a layered method or cyclone smelting sublimates. Application of the method to coarse materials, such as a mixture of fly ash and fly ash from the burning of coal and carbonaceous rocks (mudstones and siltstones) in layered furnaces, reveals its shortcomings. The feasibility of joint processing of fly ash and fly ash is determined by the need to increase the overall extraction of germanium from carbon raw materials, since up to 50% of the germanium entering the combustion process goes into coarse dust (fly ash).

The disadvantages of the closest analogue are:

- the impossibility of obtaining after wetting and agglomeration of the mixture (by pelletizing or briquetting) from coarse materials with a maximum particle size of up to 2 ÷ 4 mm, such as a mixture of fly ash and fly ash from burning coal, agglomerated material with mechanical granulation required for melting with sublimation and thermal resistance;

- when melting the agglomerated material prepared in accordance with the closest analogue, the extraction of germanium in sublimates is not more than 60–70% instead of the required 90–92%;

- the multiplicity of enrichment of sublimates with Germany is within 10 ÷ 15 times instead of the necessary not less than 25 ÷ 40 times;

- there is a decrease in furnace productivity and an increase in the consumption of electricity and electrodes for melting by 2 ÷ 2.5 times.

The objective of the present invention is to provide a method that allows the processing of coarse dispersed germanium-containing materials, such as a mixture of fly ash and fly ash from coal combustion, to produce sublimates with an enrichment ratio of 25 ÷ 40, meeting the requirements for sublimates used for the production of germanium concentrates, according to the germanium content, and impurities, as well as indicators for the extraction of Germany, and, in addition, to increase the productivity of the electric furnace, reduce the cost of electricity, achieve technical and economic indicators lei, ensuring the profitability of production.

The technical result of the invention is to increase the extraction of germanium in sublimates from 66-70% to 90-95% by improving the quality of the agglomerated charge in terms of mechanical and thermal strength and increasing the multiplicity of enrichment of sublimates from 28-31 to 40-51 times with an increase in electric furnace productivity in 2.3 times and a decrease in energy consumption by 2.5 and electrodes by 1.6 times.

The specified technical result is achieved by the fact that in the method of extracting germanium, which includes preparing the initial charge from a germanium-containing material, a sulfidizing agent and a reducing agent, moistening the resulting mixture, sintering and melting in an electric furnace while maintaining a charge layer on the melt surface with a thickness of 0.1-0.3 m, according to the invention, the preparation of the mixture is carried out using as a germanium-containing material a mixture of fly ash and fly ash from the combustion of germanium-containing carbon raw materials, the prepared mixture Ed moisture is pulverized to a particle size of not more than 0.4 mm, are briquetted prior to agglomeration humidity 12-18% and agglomerated batch before the melting is kept for 7-8 h.

In addition, the agglomerated charge before melting is subjected to drying at a temperature of 70-120 ° C.

Finally, the agglomerated charge before melting is subjected to separation by sieving with the allocation of fractions minus 5 mm, directed to grinding the charge before wetting and agglomeration.

In accordance with the invention, preliminary grinding of the initial charge to a particle size of not more than 0.4 mm and holding the agglomerated charge for 7 ÷ 8 hours make it possible to improve the quality of the agglomerated charge, in particular, the compressive and impact strength of pellets (briquettes) and a low fraction output of minus 5 mm . This ensures the particle size distribution of the charge, necessary for subsequent melting to produce sublimates with a high multiplicity of enrichment with germanium and increased germanium extraction in them.

The possibility of carrying out the invention is illustrated by the following examples.

Example 1. A mixture of fly ash from the combustion of germanium coals in a fluidized bed containing on a dry mass,%: 1.80 Ge; 3.57 Fe _total ; 9.67 C; 16.6 Al ₂ O ₃ ; 2.83 CaO; 1.00 MgO; 1.14 S was processed according to the invention and the closest analogue. Comparative testing was carried out on laboratory models of a vibrating grinder, drum pelletizer, briquette press and electric furnace equipped with a gas exhaust system with air supply for oxidizing sublimates and filtering gas in a bag filter with Polin 7 filter cloth. Testing of the heat was carried out in periodic mode.

The composition of the charge was taken from the calculation of the sulfur content in the charge equal to 5%. Calcium sulfate hemihydrate (alabaster) was used as a sulfidizing agent. The required amount of carbonaceous reducing agent was contained in the ash; therefore, no carbonaceous reducing agent was introduced into the charge. Calcium oxide from alabaster, as well as additionally from calcium oxide hydrate (lime-fluff), served as fluxes to obtain slag, the composition necessary for melting. Alabaster and calcium oxide hydrate were also components of a binder for sintering the mixture.

The constituent charges in accordance with the closest analogue were subjected to mixing, moistening and agglomeration by pelletizing or briquetting at a pressing pressure of 500 kg / cm ² . The finished mixture was sent for melting.

When processing a mixture of fly ash and fly ash in accordance with the invention, the mixture was subjected to mixing and grinding, moistening and agglomeration in the same ways. The finished mixture after exposure for 7-8 hours was sent for melting.

The heating rate of the agglomerated charge in the electric furnace was maintained equal to 20 deg / min to a temperature of 1550 ° C, followed by exposure of the melts at this temperature for 30 minutes. The processing results according to the invention and the closest analogue are shown in table 1. From a comparison of the data it is seen that the use of the invention allows:

- increase the strength of the agglomerated mixture in compression and impact by 3 ÷ 5 times;

- reduce the yield of the fraction minus 5 mm and thereby ensure the particle size distribution of the mixture, necessary for subsequent melting with obtaining sublimates;

- when sintering by briquetting, reduce the moisture content of the material that has been sintered from 25 ÷ 30 to 15 ÷ 18%, which allows to reduce the energy consumption for melting by an average of 15%;

- reduce the loss of germanium with slag, eliminate the formation on the surface of the slag of a refractory layer enriched with germanium, which allows to increase the extraction of germanium in sublimates from 70 to more than 90%;

- increase the multiplicity of enrichment of sublimates with Germany in 1.5 ÷ 2 times.

Example 2. A mixture of fly ash and fly ash from coal burning, containing 1.9% germanium, was processed in an industrial plant, including compartments of charge, pelletizing and electric melting (electric furnace with transformer 500 KVA). The mixture after pelletizing was kept in the container for 7-8 hours. To verify the invention, a ball mill for mixing and grinding the charge was included in the apparatus circuitry. The processing results (table 2) confirmed that grinding the mixture before wetting and agglomeration, followed by exposure of the agglomerated mixture and in industrial conditions allows you to:

- eliminate the formation of a refractory layer enriched with germanium on the surface of the slag melt and ensure the continuity of the melting process;

- reduce the loss of germanium with slag, increase the extraction of germanium in coarse dust and sublimates from 66.5 to more than 90%;

- increase the multiplicity of enrichment of sublimates;

- increase the productivity of the furnace and reduce the consumption of electricity and electrodes, thereby ensuring the profitability of processing.

Example 3. A mixture of fly ash and fly ash from coal combustion in accordance with the invention was processed according to example 2, and also was heated in a heated hopper at 70 ÷ 120 ° C for 2 hours. When melting the dried mixture to a moisture content of 5–7%, the electric energy consumption decreased by 10% with constant extraction and multiplicity of enrichment of sublimates.

Example 4. The granulated charge according to examples 2 and 3 was subjected to sieving before melting with a screen with separation of a fraction minus 5 mm and returning it to grinding, moistening and agglomeration. Melting of the fraction allowed to increase the germanium content in sublimates from 47.2% to 54.3%, i.e. increase the multiplicity of enrichment of sublimates by 15% (relative).

Table 1 Comparison of processing parameters of a mixture of fly ash and fly ash from coal combustion according to the invention and the closest analogue in laboratory models No pp unit of measurement Indicator values The name of indicators proposed invention nearest analogue one 2 3 four 5 one The composition of the charge:
- a mixture of fly ash and fly ash % 59.75 59.75 - lime fluff % 15.45 15.45 - alabaster % 24.80 24.80 2 The duration of the grinding mixture min twenty 0 3 The maximum particle size of the mixture before wetting mm 0.4 2,4 four The strength of the pellets (briquettes) after sintering and aging - compression kg / pellet (kg / cm ² ) 5 (20) 1 (5) - to hit number of discharges from 1 m to concrete 3 (2) 1 (2) 5 The output of the fraction minus 5 mm when sieving pellets (briquettes) % 5 (1,5) 70 (30) 6 Humidity: - Pellets % 25 thirty - briquettes % fifteen eighteen 7 Content in the mixture (on a dry mass): - sulfur % 5,0 5,0 - carbon % 5.8 5.8 - germany % 1,08 1,08 8 The basicity of the charge dimensionless 0.75 0.75 9 Germany distribution: - slag % 1.0 (0.2) 8.1 (10.0) - sulfide-metal alloy % 0.8 (1.1) 5.5 (12.3) - sublimates % 95.2 (95.7) 70.4 (71.1) - non-melting layer on the surface of the slag melt % 0,0 (0,0) 4.0 (4.6) - losses through the filter % 1.0 (1.0) 1.0 (1.0) - mechanical losses % 2.0 (2.0) 1.0 (1.0) 10 The outputs of the products during the melting of pellets (briquettes): - slag % 69.9 (75.0) 69.1 (70.3) - sulfide metal alloy % 2.1 (3.1) 1.2 (3.3) - sublimates % 2.0 (2.0) 2.5 (2.3) - non-melting layer on the surface of the slag melt % no 14.1 (15.7) eleven Germanium content: - in slag g / t 155 (29) 1269 (1536) - in a sulfide-metal alloy % 0.41 (0.38) 0.50 (0.40) - in sublimates % 51.40 (51.68) 30.41 (33.39) - in a non-melting layer on the surface of the slag melt % - 0.31 (0.32)

table 2 Comparison of processing parameters of a mixture of fly ash and fly ash according to the invention and the closest analogue in an industrial plant No pp The name of indicators unit of measurement Indicator values proposed invention nearest analogue one 2 3 four 5 one The composition of the charge:
- a mixture of fly ash and fly ash % 62.0 62.0 - lime fluff % 21.0 21.0 - alabaster % 17.0 17.0 2 The duration of the grinding mixture hour four 0 3 The maximum particle size of the mixture before wetting mm 0.4 2.5 four Pellet moisture % 25 thirty 5 Content in the mixture (on a dry mass): - sulfur % 3.9 3.9 - carbon % 5.8 5.8 - germany % 1.18 1.18 6 The outputs of the products during the melting of pellets (from dry mixture): - slag % 76.0 66.0 - sulfide metal alloy % 3,1 1,2 - sublimates % 1,6 1,5 - cyclone dust % 2.5 2.0 - non-melting layer on the surface of the molten slag % no 12.7 7 Germanium content: - in slag g / t 220 1300 - in sulfide-metal alloy % 0.76 2.0 - in sublimates % 47.2 34.9 - cyclone dust % 12,4 13.1 - in a non-melting layer on the surface of the slag melt % - 1.7 8 Germany distribution: - slag % 1,0 7.3 - sulfide-metal alloy % 2.0 2.6 - sublimates % 91.0 66.5 - non-melting layer on the surface of the slag melt % 0,0 18.3 - losses through the filter % 4.0 4.0 - mechanical losses % 2.0 1.3 9 Electric furnace performance t / day 3,5 1,5 10 Power consumption KWh / t wet charge 1350 3430 eleven Electrode consumption Kg / t wet mixture 7.5 12.0 12 The amount of processed charge t 28 1.5 oven stopped after 24 hours 13 Profitability of processing % 32,3 no

Thus, the examples confirm the possibility of industrial application of the invention.

Claims (3)

1. A method of extracting germanium from a germanium-containing material, comprising preparing a mixture by mixing germanium-containing material, a sulfidizer and a reducing agent, moistening the resulting mixture, sintering and melting in an electric furnace while maintaining a charge layer on the melt surface with a thickness of 0.1 ÷ 0.3 m, characterized in that the mixture is prepared using a mixture of fly ash and fly ash from the combustion of germanium-containing carbon raw materials as a germanium-containing material, the prepared mixture before moistening jected milled to a particle size of not more than 0.4 mm, agglomeration leads to a briquetting humidity of 12 ÷ 18% and agglomerated batch before the melting incubated for 7 ÷ 8 hours. 2. The method according to claim 1, characterized in that the agglomerated charge before melting is subjected to drying at a temperature of 70 ÷ 120 ° C. 3. The method according to any one of claims 1 and 2, characterized in that the agglomerated charge before smelting is subjected to sieving with separation of the fraction minus 5 mm with its return to grinding.