A method for secondary recovery of germanium from low-grade germanium-containing materials

Abstract

The present invention discloses a method for secondary recovery of germanium from low-grade germanium materials. Specifically, the low-grade germanium materials are leached by the sub-molten salt method to obtain a germanium-containing alkaline leaching solution and an alkaline leaching residue; whether to adopt an aluminum removal process is determined according to the aluminum content in the germanium-containing alkaline leaching solution. After ensuring that the aluminum content meets the standard, germanium is selectively adsorbed by D403 resin. The alkaline solution after germanium extraction can be concentrated and crystallized and then used for sub-molten salt leaching again; the D403 chelating resin adsorbed with germanium is desorbed with a hydrochloric acid solution, and the desorbed D403 chelating resin is activated and regenerated and then re-adsorbs germanium; the germanium-containing hydrochloric acid solution can be used to produce germanium oxide by adjusting the pH value or be formulated with concentrated hydrochloric acid for distilling germanium concentrate. The present invention realizes the efficient leaching of germanium from low-grade germanium materials. After selective adsorption by chelating resin, desorption and then germanium precipitation are carried out, and the enrichment ratio can reach more than 80. By dissolving germanium and other impurities in low-grade germanium materials by the sub-molten salt method, the iron or calcium content in the alkaline leaching residue after germanium dissolution increases and can be used as a metallurgical flux, building materials or raw material for ironmaking.

Description

Technical Field

[0001] The present invention relates to a method for secondary recovery of germanium from low-grade germanium materials, and particularly to a method for preparing high-grade germanium concentrate from low-grade germanium materials containing high iron and silicon, such as neutralization slag, displacement slag, leaching slag, furnace slag, and soot in the zinc hydrometallurgy process, belonging to the technical field of chemical metallurgy. Background Art

[0002] Germanium has amphoteric characteristics and belongs to the category of rare dispersed metals (abbreviation: scattered metals). In different geochemical environments, germanium exhibits different geochemical properties, including lithophile, siderophile, chalcophile, and organophile properties. Therefore, independent ores are relatively limited, and germanium is enriched in Fe-Ni phases (meteorites and the earth's core), sulfides rich in lead, zinc, silver, and copper, iron oxide deposits (limonite, magnetite, and goethite), oxidation zones of germanium-rich sulfides (hydroxides, oxides, hydroxy sulfates, and arsenates), coal, and lignite (bonded with organic matter). Among them, the recovery of germanium from zinc sulfide concentrate and lignite is the main source of germanium. It is statistically shown that nearly 60% of germanium comes from various slag and by-products of zinc smelting enterprises.

[0003] During the zinc smelting process, along with the zinc extraction process, germanium enters the leaching slag, soot, neutralization slag, displacement slag, hard zinc, and offcut zinc, etc., and germanium is enriched to varying degrees compared with the original ore. However, for low-grade germanium materials with a germanium content of 0.1 - 2.0%, if directly used in the germanium smelting process, it will lead to low germanium recovery rate, and a large amount of other components in the low-grade germanium materials consume a large amount of hydrochloric acid. The waste hydrochloric acid and residues generated during the distillation process are often difficult to effectively utilize, and the environmental protection disposal is difficult.

[0004] To enrich and recover germanium from low-grade germanium-containing materials, pyrometallurgy, hydrometallurgy, or a combination of both can be used. Pyrometallurgy usually requires large furnaces such as Waelz rotary kilns, fuming furnaces, electric arc furnaces, and Ausmelt furnaces, and high-temperature carbon reduction or sulfide volatilization processes are selected for treatment to produce germanium oxide or germanium sulfide-containing dust. The pyrometallurgical volatilization method cannot completely break the connection between germanium and iron, silicon, and sulfur, resulting in low germanium recovery rate, low germanium content in the dust, and part of the germanium entering the kiln slag, making it difficult to recover. In addition, the low-concentration sulfur dioxide flue gas produced during the volatilization process is difficult to treat. The hydrometallurgical process usually uses sulfuric acid leaching. For some refractory materials, oxygen pressure leaching, ultrasonic strengthening, and adding leaching aids such as ozone, hydrogen peroxide, manganese dioxide, sodium chlorate, sodium acetate, and citric acid can be used to improve the germanium leaching rate to a certain extent. After germanium dissolves in the sulfuric acid solution, germanium is precipitated with tannic acid or extracted with an extractant to obtain a high-grade germanium concentrate. Germanium can be directly obtained as germanium slag by tannic acid precipitation, and after calcination, it can be used as germanium concentrate for further germanium extraction. After germanium extraction, it is washed and back-extracted, and then the pH value is adjusted with an alkali solution to obtain crude germanium dioxide. In recent years, the price of tannic acid has been high, and the unit consumption of tannic acid for germanium precipitation is high, resulting in high costs for the germanium precipitation method using tannic acid; while the germanium extraction process is long, and the fluorine in the back-extraction agent enters the solution and is difficult to treat. In addition, for both the germanium precipitation method using tannic acid and the germanium extraction method, tannic acid and organic extractants will dissolve into the solution to a certain extent, affecting subsequent processes.

[0005] With the increasing environmental protection requirements and the urgent need of enterprises to reduce costs and energy consumption, it is necessary to develop a secondary recovery technology with high recovery rate, simple process, short process flow, easy operation, recyclable auxiliary materials, and low energy consumption for low-grade germanium materials and prepare high-grade germanium concentrates. Summary of the Invention

[0006] The present invention proposes a method for secondary recovery of germanium from low-grade germanium materials, adopting the process of sub-molten salt leaching-ion exchange adsorption, recovering germanium in the form of crude germanium dioxide from low-grade germanium materials, and the alkali leaching residue can be recycled, without waste water and waste residue.

[0007] The specific process steps to achieve the object of the present invention are as follows:

[0008] Step 1

[0009] React the low-grade germanium-containing material with a sub-molten salt medium in a reaction kettle at 70-250 °C to carry out medium-temperature alkali leaching and / or sub-molten salt leaching reaction. The sub-molten salt medium contains alkali metal hydroxide; after the reaction is completed, filter and wash to obtain a germanium-containing alkali leaching solution and an alkali leaching residue;

[0010] Step 2

[0011] If the aluminum content in the germanium-containing alkaline leaching solution is greater than or equal to Amg / L, the germanium-containing alkaline leaching solution is subjected to aluminum removal treatment to obtain aluminum slag and a purified germanium-containing solution; the purified germanium-containing solution passes through an ion exchange column filled with D403 chelating resin to obtain chelating resin adsorbed with germanium and germanium-extracted alkaline solution;

[0012] If the aluminum content in the germanium alkaline leaching solution is less than Amg / L, the germanium-containing alkaline leaching solution passes through an ion exchange column filled with D403 chelating resin to obtain chelating resin adsorbed with germanium and germanium-extracted alkaline solution;

[0013] The value range of A is 20 - 50.

[0014] The present invention first applies the sub-molten salt leaching reaction to the treatment of low-grade germanium-containing materials, and realizes the low-temperature and high-efficiency recovery of germanium under the coordination of corresponding condition parameters.

[0015] The present invention inputs low-grade germanium-containing materials and sub-molten salt medium into a reaction kettle to carry out sub-molten salt leaching reaction. By regulating process technical parameters such as reaction temperature, oxygen partial pressure, alkali concentration, alkali-ore ratio, and reaction time, under the coupling action conditions of multiple factors, germanium in the germanium-containing materials reacts with the alkaline solution to form sodium germanate alkaline leaching solution, and amphoteric elements such as zinc, aluminum, silicon, and arsenic in the germanium-containing materials are almost all dissolved into the alkaline leaching solution.

[0016] The germanium content in the low-grade germanium materials described in the present invention is 0.1 - 2.0 wt%.

[0017] When applied industrially, germanium in the low-grade germanium materials mainly exists in the forms of germanium monoxide, germanium dioxide, germanium sulfide, germanate, and germanium-silicon solid solution, and iron mainly exists in the forms of oxides and hydroxides. Of course, the method of the present invention can also be applicable to germanium occurring in other forms.

[0018] The present invention provides a method for secondary recovery of germanium from low-grade germanium materials. In step one, according to the alkali-ore ratio g:g = 5 - 20:1, an alkali with a concentration of 50 - 90 wt% is used, and a co-solvent is added in a proportion of 0 - 5% based on the feeding amount and mixed with the low-grade germanium materials. The sub-molten salt medium and the low-grade germanium materials are loaded into the reaction kettle, the kettle cover is closed, stirring is started, an oxygen-containing gas is introduced, and the oxygen partial pressure is controlled at 0.05 - 2.00 MPa. The reaction temperature is controlled at 140 - 250 °C, preferably 160 - 180 °C. After continuously reacting for 1 - 6 h, the intake valve is closed, and after cooling to 80 - 120 °C, heat preservation filtration is carried out. When a co-solvent needs to be added, the addition proportion of the co-solvent can be 0.2 - 5%.

[0019] Certainly, the solution of the present invention also includes: according to the alkali ore ratio g:g = 5 - 20:1, mixing alkali with a concentration of 50 - 90 wt% with low-grade germanium materials, loading the alkali, the cosolvent and the medium-temperature alkali leaching residue into a reaction kettle, closing the kettle lid and starting stirring, introducing an oxygen-containing gas and controlling the oxygen partial pressure to be 0.05 - 2.00 MPa, controlling the reaction temperature to be 140 - 250 °C, preferably 160 - 180 °C, continuously reacting for 1 - 6 h, then closing the inlet valve, cooling to 80 - 120 °C and filtering while maintaining the temperature.

[0020] In the present invention, according to the alkali ore ratio g:g = 3 - 10:1, mixing alkali solution B with low-grade germanium materials, leaching the germanium-containing materials with the alkali leaching solution of the sub-molten salt method at 80 - 90 °C without boiling to obtain the first alkali residue; then carrying out the second sub-molten salt leaching, and using the residue of the first stage as the raw material for the second sub-molten salt leaching.

[0021] The alkali solution B is the alkali solution after sub-molten salt leaching or an alkali solution with a concentration of 10 - 40%.

[0022] When the present invention is applied industrially, according to the alkali ore ratio g:g = 3 - 1:1, mixing the alkali leaching solution adsorbed with germanium with a concentration of 100 - 150 g / L with low-grade germanium materials, reacting at 80 - 90 °C without boiling, about 50% of germanium can be leached out, and the rest of the amphoteric impurities (aluminum, silicon, zinc, arsenic) are partially leached out. Then carry out the second sub-molten salt leaching, and use the medium-temperature alkali leaching residue of the first stage as the raw material for the second sub-molten salt leaching. The two-stage leaching combining medium-temperature alkali leaching and sub-molten salt leaching is especially suitable for germanium materials containing amphoteric elements such as aluminum, silicon, arsenic, and zinc. The advantages are as follows: 1. The germanium concentration in the alkali leaching solution can be increased by about 50%, which is beneficial to the subsequent adsorption. 2. After the first-stage alkali leaching of the germanium-containing materials, the weight is reduced a lot, and the second-stage sub-molten salt process is more efficient to process, and the alkali-solid ratio can also be reduced. The second sub-molten salt leaching here is carried out according to the above process. That is, according to the alkali ore ratio g:g = 5 - 20:1, mixing the alkali with a concentration of 50 - 90 wt% with the residue of the first stage and / or low-grade germanium materials, loading the alkali, the cosolvent and the low-grade germanium materials into a reaction kettle, closing the kettle lid and starting stirring, introducing an oxygen-containing gas and controlling the oxygen partial pressure to be 0.05 - 2.00 MPa, controlling the rotation speed to be 300 - 900 revolutions per minute, controlling the reaction temperature to be 140 - 250 °C, preferably 160 - 180 °C, continuously reacting for 1 - 6 h, then closing the inlet valve, cooling to 80 - 120 °C and filtering while maintaining the temperature. 3. The sub-molten salt alkali leaching solution is returned to the medium-temperature alkali leaching, which can make full use of the heat of the sub-molten salt alkali leaching solution. In addition, the medium-temperature alkali leaching consumes part of the alkali in the sub-molten salt alkali leaching solution, which is beneficial to extending the service life of the resin.

[0023] The present invention for the first time adopts a two-stage leaching method combining medium-temperature alkali leaching and sub-molten salt leaching, which can significantly increase the germanium concentration in the alkali leaching solution. In addition, medium-temperature alkali leaching can partially dissolve components such as germanium, aluminum, arsenic, silicon, and zinc in low-grade germanium materials, reducing the low-grade germanium materials by 30-50%, effectively reducing the alkali-to-ore ratio in sub-molten salt leaching, greatly improving the equipment utilization efficiency, and additionally making full use of heat and prolonging the resin life.

[0024] In the present invention, the oxygen-containing gas is industrial oxygen. Industrial oxygen shall be implemented according to corresponding standards.

[0025] In the present invention, the alkali metal hydroxide is selected from at least one of sodium hydroxide and potassium hydroxide; that is, the alkali metal hydroxide in step one is selected from at least one of sodium hydroxide and potassium hydroxide.

[0026] The sub-molten salt medium includes an alkali metal hydroxide or includes an alkali metal hydroxide and a co-solvent; the co-solvent is selected from at least one of nitrates, carbonates, and chlorates, preferably at least one of sodium nitrate, potassium nitrate, sodium carbonate, potassium carbonate, sodium chlorate, and potassium chlorate; for specific materials containing germanium oxide phases that are easily soluble, the co-solvent may not be added.

[0027] In the present invention, the alkali-to-ore ratio is the ratio of the material to the alkali metal oxide.

[0028] In the present invention, when a co-solvent needs to be added, such as the feeding amount of sodium nitrate, it should be in a proportion of 0.2-5% of the feeding amount according to the content of the insoluble germanium component in the material.

[0029] In the present invention, the alkali concentration refers to the ratio of the alkali to the weight of the alkali + water.

[0030] In industrial applications, the sub-molten salt medium is prepared by mixing an alkali and a pure nitrate in a set ratio during the initial production, and then using the germanium-extracted alkali leaching solution produced in step three, which is the solid alkali after evaporation and concentration.

[0031] In step 1 of the present invention, the rotation speed is controlled at 300-900 revolutions per minute.

[0032] What is mainly produced in step one is the alkali leaching solution containing germanium and the residue after germanium extraction. The germanium concentration in the alkali leaching solution containing germanium is 100-2000 mg / L, the alkali concentration is 10-250 g / L, and the germanium content in the residue after germanium extraction is less than 400-1000 g / t.

[0033] In step two of the present invention, when the aluminum content in the germanium-containing alkaline leaching solution is greater than or equal to Amg / L, the germanium-containing alkaline leaching solution uses a combined aluminum removal agent of sodium silicate and silicon dioxide to precipitate and separate aluminum, etc., to obtain aluminum slag and a purified solution containing germanium. Specifically: control the molar ratio of sodium silicate to aluminum in the germanium-containing alkaline leaching solution to be 1.5 - 2.0, react at 150 - 160 °C for 30 - 120 min, to obtain a filter residue with an aluminum content of 5 - 30%, and a purified solution of germanium alkaline leaching solution with an aluminum concentration lower than Amg / L. The value range of A is 20 - 50.

[0034] As a further preference, the mass ratio of sodium silicate to silicon dioxide is 65 - 75:35 - 25., and sodium silicate is preferably sodium silicate nonahydrate.

[0035] In step two of the present invention, the germanium-containing alkaline leaching solution with an aluminum content less than Amg / L passes through an ion exchange column filled with D403 resin at a flow rate of 5 - 30 BV / h, to obtain the resin adsorbed with germanium and the alkaline solution after germanium extraction. The alkaline leaching solution after germanium extraction is evaporated and concentrated and then returned to step one as the sub-molten salt medium. In the present invention, D403 resin is a macroporous styrene chelating type ion exchange resin, which is a milky white opaque spherical particle.

[0036] In step two of the present invention, when using the ion exchange column of D403 resin to adsorb germanium, control the temperature to be 20 - 65 °C, preferably 20 - 35 °C.

[0037] After completing step two of the present invention, the saturated resin adsorbed with germanium, after being thoroughly washed and rinsed, is desorbed with hydrochloric acid solution to obtain a hydrochloric acid solution containing germanium and D403 resin that no longer adsorbs germanium. When applied industrially, the germanium adsorbed on D403 resin is eluted with a hydrochloric acid solution with a concentration of 0.2 - 4.0 mol / L, the dosage of the hydrochloric acid solution is 2 - 4m 3 / m 3 -R, the flow rate of the hydrochloric acid solution is 10 - 25 BV / h, and the operating temperature is 20 - 35 °C.

[0038] The present invention first uses D403 resin to adsorb germanium under alkaline conditions, which provides a necessary condition for the efficient recovery of germanium.

[0039] In the present invention, "m 3 / m 3 -R" refers to how many cubic meters of hydrochloric acid are required per cubic meter of resin.

[0040] When applied industrially, the resin adsorption can adsorb germanium in the solution completely, but in actual operation, generally, it is not done like this considering efficiency and cost, only a part is adsorbed, and the rest remains in the solution for recycling. For example, it can be reduced from 800 mg / L to 300 mg / L.

[0041] When applied industrially, after transformation and activation, D403 returns to Step 2 for recycling. The methods of transformation and activation include all existing methods.

[0042] After obtaining the germanium-containing hydrochloric acid solution of the present invention, a germanium precipitation aid is added, and the pH value is adjusted to 8.0 - 10.0 with an alkali at room temperature to precipitate germanium. After filtration, a high-grade germanium concentrate with a germanium content of greater than or equal to 20%, preferably greater than or equal to 30%, is obtained. Specifically, the germanium precipitant that can be selected can be ferric chloride or magnesium chloride alone, or a mixture of ferric chloride and magnesium chloride. The alkali used for pH adjustment is selected from at least one of sodium hydroxide, sodium carbonate, and ammonia.

[0043] The present invention uses low-grade germanium materials with a germanium content of 0.2 - 2.0% as raw materials, and adopts the method of low-temperature leaching by the sub-molten salt method - ion exchange resin adsorption to enrich germanium twice. Compared with pyrometallurgical volatilization, acid dissolution, and leaching with a single sodium hydroxide aqueous solution, the germanium leaching rate is higher. The selected N-methylglucamine - polystyrene macroporous chelating resin has strong selectivity and large saturation capacity for adsorbing germanium. Based on this principle, the present invention adopts the technical scheme of recovering germanium from low-grade germanium materials by the method of alkali leaching by the sub-molten salt method - D403 resin adsorption. This scheme reacts low-grade germanium materials with excessive sodium hydroxide or potassium hydroxide in a sub-molten salt state to break the stable structures of germanium dioxide, germanium sulfide, and silicon-germanium solid solution. Germanium combines with hydroxide ions to form germanate ions and enters the solution. After chemical removal of aluminum, the D403 macroporous resin can selectively adsorb germanium from the solution onto the resin, while impurities such as silicon, arsenic, and zinc are hardly adsorbed. After adsorption - desorption, germanium enters the hydrochloric acid solution and can be directly used as the feed for the germanium distillation process or the pH value is adjusted with an alkali to generate crude germanium dioxide, thereby achieving the goal of efficiently recovering germanium from low-grade germanium-containing materials. The main chemical reaction equations involved in the present invention are as follows:

[0044] GeO2 + 2NaOH = Na2GeO3 + H2O

[0045] GeO + 2NaOH = Na2GeO2 + H2O

[0046] GeO2·SiO2 + 4NaOH = Na2GeO3 + Na2SiO3 + 2H2O

[0047] As2O3 + 6NaOH = 2Na3AsO4 + H2O

[0048] Al2O3 + 2NaOH = 2NaAlO2 + H2O

[0049] SiO2 + 2NaOH = Na2SiO3 + H2O

[0050] Zn2SiO4 + 6NaOH = Na2SiO3 + 2Na2ZnO2 + 3H2O

[0051] ZnO + 2NaOH = Na2ZnO2 + H2O

[0052] Na2SiO3 + NaAlO2 + H2O = Na2Al2Si2O8 + 4NaOH

[0053] Advantages of the present invention:

[0054] (1) High - efficiency recovery of germanium. For the first time in the present invention, germanium and other amphoteric elements in low - grade germanium materials are dissolved by alkali and cosolvent in the sub - molten salt state. Aluminum in the alkali leaching solution is removed by chemical precipitation method, and germanium is highly selectively adsorbed (the enrichment ratio can reach more than 80) through ion - exchange adsorption using D403 macroporous resin. After being desorbed with hydrochloric acid solution, it can be directly used for germanium processing to produce high - purity germanium tetrachloride or precipitate germanium to prepare crude germanium dioxide, realizing the secondary recovery of germanium in low - grade germanium materials. The germanium leaching rate of the sub - molten salt process can reach 96% and above, and the overall - process germanium recovery rate can reach 94.5% and above.

[0055] (2) High - value utilization of iron. In the present invention, during the medium - temperature alkali leaching and sub - molten salt leaching processes, iron is hardly dissolved and enters the alkali leaching residue. Based on the dissolution of germanium and other amphoteric elements, the residue rate of the alkali leaching residue is 30 - 60%, and iron is enriched in the form of oxides. The iron content in the alkali leaching residue is 40 - 60%. The obtained alkali leaching residue can be used as a metallurgical flux or building materials. For the alkali leaching residue with an iron content greater than 50%, it can be used as raw material for iron smelting, realizing the high - value utilization of iron.

[0056] (3) Clean and efficient smelting process. The present invention adopts the sub - molten salt alkali leaching process or the medium - temperature alkali leaching connected to the sub - molten salt alkali leaching process, with low reaction temperature, less energy consumption, and the alkali in the sub - molten salt medium can be recycled. After chelating ion - exchange resin adsorption - desorption, it can be reused after simple activation and transformation. The resin is insoluble in the solution, so it will not introduce an organic phase, and the adsorption - desorption process can be carried out at room temperature. Iron is enriched in the alkali leaching residue and can be resourcefully utilized, with no waste water and waste residue discharged. Description of the Drawings

[0057] Appendix Figure 1 is the optimized process flow chart of the present invention. Detailed Embodiments

[0058] Taking low - grade germanium slag from zinc hydrometallurgy as raw material, the present invention will be further described in detail through examples, but the protection scope of the present invention is not limited to the content described.

[0059] Example 1:

[0060] The leaching residue in the zinc hydrometallurgy process is the zinc - germanium - lead - containing dust after high - temperature volatilization in a fuming furnace. The dust is leached with sulfuric acid and then the neutralization residue with a pH value adjusted to 5.0 by adding zinc calcine or zinc - containing dust. The main chemical components of the germanium - containing neutralization residue after separating zinc are shown in Table 1.

[0061] Main chemical components of the neutralized slag in Table 1 (wt%)

[0062]

[0063] (1) Control the alkali-to-solid ratio (g:g) of sodium hydroxide to neutralized germanium slag to be 8. Place the neutralized germanium slag in a closed reaction kettle containing 80 wt% sodium hydroxide, react at 170 °C for 2 h, filter while hot, and wash the slag with 80 °C hot water to produce an alkali leaching solution and an alkali leaching residue. The germanium concentration in the alkali leaching solution is 384 mg / L, the iron concentration is 5.78 mg / L, the aluminum concentration is 2.12 g / L, and the alkali leaching residue with an iron content of 41.46 wt%; after one-step leaching, the leaching rate of germanium is approximately 96.35%.

[0064] (2) Add an aluminum-removing agent to the germanium-containing alkali solution (the aluminum-removing agent consists of sodium silicate and silicon dioxide with a mass ratio of sodium silicate nonahydrate:silicon dioxide being 7:3). The molar ratio of the total amount of sodium silicate in the aluminum-removing agent to aluminum in the solution is 1.5:1, and then react at 160 °C for 90 min to precipitate and separate aluminum, obtaining a germanium-containing alkali leaching solution with aluminum below 20 mg / L and an aluminum slag with an aluminum content of 6.17 wt%;

[0065] (3) At room temperature, the germanium-containing alkali leaching solution passes through an ion exchange column loaded with D403 resin at a flow rate of 18 BV / h to obtain a low-germanium alkali leaching solution with a germanium concentration of 1.26 mg / L. Germanium is adsorbed by the resin particles, and the low-germanium alkali leaching solution is returned to step (2) after evaporation and concentration.

[0066] (4) The resin particles adsorbed with germanium are washed twice with pure water, and germanium is desorbed with a 2 mol / L hydrochloric acid solution at a flow rate of 10 BV / h. The desorption solution can be recycled until the germanium concentration is enriched to more than 2 g / L. The desorbed resin is returned to step (3) after activation and transformation.

[0067] (5) The germanium-containing hydrochloric acid solution is directly transferred to the distillation and germanium extraction process for batching or a germanium precipitation agent is added to adjust the pH to 10.0 to obtain crude germanium oxide with a germanium content of 41.33 wt%.

[0068] In this example, the recovery rate of germanium is approximately 95.86%.

[0069] Example 2:

[0070] The leaching solution in the oxygen pressure acid leaching process of hydrometallurgical zinc smelting is adjusted by flash evaporation and then zinc calcine or zinc-containing dust is added to adjust the pH value to 5.0 to obtain the neutralized slag. The main chemical components of the neutralized slag after zinc separation are shown in Table 2.

[0071] Main chemical components of the neutralized slag in Table 2 (wt%)

[0072]

[0073] (1) Control the alkali-solid ratio (g:g) of sodium hydroxide to neutralized germanium slag to be 6. Place the neutralized germanium slag in a closed reaction kettle containing 80 wt% sodium hydroxide, control the oxygen partial pressure to 0.5 MPa, react at 160 °C for 3 h, perform hot filtration and wash the slag with 80 °C hot water to produce an alkali leaching solution and an alkali leaching residue. The germanium concentration in the alkali leaching solution is 264 mg / L, the iron concentration is 6.17 mg / L, the aluminum concentration is 0.89 g / L, and an alkali leaching residue with an iron content of 55.68 wt%. After one-step leaching, the leaching rate of germanium is approximately 94.47%.

[0074] (2) Add an aluminum removal agent to the germanium-containing alkali solution (the aluminum removal agent is composed of sodium silicate and silicon dioxide in a mass ratio, sodium silicate nonahydrate: silicon dioxide is 7:3). The molar ratio of the total amount of sodium silicate in the aluminum removal agent to aluminum in the solution is 1.8:1, and then react at 150 °C for 60 min to precipitate and separate aluminum, obtaining a germanium-containing alkali leaching solution with aluminum below 20 mg / L and an aluminum slag with an aluminum content of 7.35 wt%.

[0075] (3) At room temperature, the germanium-containing alkali leaching solution passes through an ion exchange column loaded with D403 resin at a flow rate of 16 BV / h to obtain a low-germanium alkali leaching solution with a germanium concentration of 1.11 mg / L. Germanium is adsorbed by the resin particles, and the low-germanium alkali leaching solution is returned to step (2) after evaporation and concentration.

[0076] (4) The resin particles adsorbed with germanium are washed twice with pure water, and germanium is desorbed with a 3 mol / L hydrochloric acid solution at a flow rate of 10 BV / h. The desorption solution can be recycled until the germanium content is greater than 2 g / L. After desorption, the resin is activated and transformed and returned to step (3).

[0077] (5) The germanium-containing hydrochloric acid solution is directly transferred to the distillation and germanium extraction process for batching or a germanium precipitation agent is added, and the pH is adjusted to 8.0 to obtain crude germanium oxide with a germanium content of 39.54 wt%.

[0078] In this example, the recovery rate of germanium is approximately 93.98%.

[0079] Example 3:

[0080] The leaching solution in the oxygen pressure acid leaching process of zinc hydrometallurgy, after flash evaporation adjustment, is neutralized with zinc calcine until the sulfuric acid content is 20 g / L, zinc powder is added for replacement and impurity removal, and germanium, copper, cadmium, etc. are replaced into the replacement slag. The main chemical components of the replacement slag after separating zinc and copper are shown in Table 3.

[0081] Table 3 Main chemical components (wt%) of the germanium replacement slag

[0082]

[0083] (1) Control the alkali-solid ratio (g:g) of sodium hydroxide to the germanium replacement slag to be 7, and the addition amount of sodium nitrate is 2 wt% of the low-grade germanium material. Place the neutralized germanium slag in a closed reaction kettle containing 80 wt% sodium hydroxide and 2 wt% sodium nitrate of the feeding amount, react at 180 °C for 4 h, filter while it is hot, and wash the slag with 80 °C hot water to produce an alkali leaching solution and an alkali leaching residue. The germanium concentration in the alkali leaching solution is 298 mg / L, the iron concentration is 2.05 mg / L, the aluminum concentration is less than 1 mg / L, and the alkali leaching residue with an iron content of 4.21 wt%; after one-step leaching, the leaching rate of germanium is about 95.21% at this time.

[0084] (2) At room temperature, the germanium-containing alkali leaching solution passes through an ion exchange column loaded with D403 resin at a flow rate of 15 BV / h to obtain a low-germanium alkali leaching solution with a germanium concentration of 1.23 mg / L. Germanium is adsorbed by the resin particles, and the low-germanium alkali leaching solution is returned to step (1) after evaporation and concentration.

[0085] (3) Wash the resin particles adsorbed with germanium twice with pure water, desorb germanium with a 3 mol / L hydrochloric acid solution at a flow rate of 12 BV / h. The desorbing solution can be recycled until the germanium content is greater than 2 g / L. After desorption, the resin is activated and transformed and returned to step (2).

[0086] (4) Directly transfer the germanium-containing hydrochloric acid solution to the distillation and germanium extraction process for batching or add a germanium precipitation agent, adjust the pH to 8.5 to obtain crude germanium oxide with a germanium content of 42.17 wt%.

[0087] In this example, the recovery rate of germanium is about 94.77%.

[0088] Example 4:

[0089] The germanium-containing soot obtained by the combustion and dust collection of germanium-containing lignite, and the main chemical components of the germanium-containing lignite soot are shown in Table 4.

[0090] Table 4 Main chemical components of the neutralized slag (wt%)

[0091]

[0092] (1) The germanium-containing lignite soot and the sodium meta-aluminate alkali leaching solution returned from step (2) are in a ratio of liquid-solid ratio g:g of 10. React the germanium-containing lignite soot and the returned alkali leaching solution in a reaction tank, control the reaction temperature at 85 °C, stir at 500 r / min, keep the temperature for reaction for 3 h, and filter to obtain a medium-temperature alkali leaching residue and a germanium-containing alkali leaching solution.

[0093] (2) Mix the sub-molten salt medium from step (4) with the medium-temperature alkaline leaching residue obtained in step (1), add a portion of potassium hydroxide to achieve a ratio of alkali to solid (g:g) of 10, a potassium hydroxide concentration of 75%, and an additional feed rate of 3% potassium nitrate in a sealed reaction kettle, and react at 175 °C for 3.5 h. Then, filter while hot to obtain an alkaline leaching solution and an alkaline leaching residue. The germanium concentration in the alkaline leaching solution is 301 mg / L, the iron concentration is 9.30 mg / L, the aluminum concentration is 4.83 g / L, and the alkaline leaching residue contains 43.88% iron; after one-step leaching, the leaching rate of germanium is approximately 93.80%.

[0094] (3) Add an aluminum-removing agent to the germanium-containing alkaline solution (the aluminum-removing agent consists of sodium silicate and silicon dioxide in a mass ratio of sodium silicate nonahydrate:silicon dioxide of 7:3), and the molar ratio of the total amount of sodium silicate in the aluminum-removing agent to the aluminum in the solution is 2.0:1. Then, react at 155 °C for 100 min to precipitate and separate aluminum, obtaining a germanium-containing alkaline leaching solution with aluminum less than 40 mg / L and an aluminum slag with an aluminum content of 25.58%;

[0095] (3) At normal temperature, the germanium-containing alkaline leaching solution passes through an ion exchange column loaded with D403 resin at a flow rate of 17 BV / h to obtain a low-germanium alkaline leaching solution with a germanium concentration of 1.57 mg / L. Germanium is adsorbed by the resin particles, and the low-germanium alkaline leaching solution is returned to step (2) after evaporation and concentration.

[0096] (4) Wash the resin particles adsorbed with germanium twice with pure water, elute germanium with a 2.5 mol / L hydrochloric acid solution at a flow rate of 9.5 BV / h. The eluate can be recycled until the germanium content is greater than 2 g / L. After elution, the resin is activated and transformed and returned to step (3).

[0097] (5) Directly transfer the germanium-containing hydrochloric acid solution to the germanium distillation and extraction process for formulation or add a germanium precipitation agent, adjust the pH to 10.0 to obtain crude germanium oxide with a germanium content of 43.45%.

[0098] In this example, the recovery rate of germanium is approximately 92.49%.

[0099] Comparative Example 1

[0100] The raw materials are the same as those used in Example 1;

[0101] Leach with a 500 g / L sodium hydroxide aqueous solution, add 20 g of raw materials, control the reaction temperature at 90 °C, the liquid-solid ratio at 10:1, and the reaction time at 2 h. After one-step leaching, the leaching rate of germanium is 47.04%.

[0102] Comparative Example 2

[0103] The raw materials are the same as those used in Example 1;

[0104] Leaching was carried out with a 500 g / L sodium hydroxide aqueous solution. 20 g of raw materials were added, 5 g of sodium chlorate was added, the reaction temperature was controlled at 90 °C, the liquid-solid ratio was 10:1, and the reaction time was 2 h. After one-step leaching, the germanium leaching rate was 42.25%.

[0105] Comparative Example 3

[0106] The raw materials were the same as those used in Example 1;

[0107] Leaching was carried out with a 500 g / L sodium hydroxide aqueous solution. 20 g of raw materials were added, 5 ml of hydrogen peroxide was added, the reaction temperature was controlled at 80 °C, the liquid-solid ratio was 10:1, and the reaction time was 2 h. After one-step leaching, the germanium leaching rate was 50.64%.

[0108] Comparative Example 4

[0109] The raw materials were the same as those used in Example 1;

[0110] Leaching was carried out with a 448 g / L potassium hydroxide aqueous solution. 10 g of raw materials were added, the reaction temperature was controlled at 90 °C, the liquid-solid ratio was 20:1, and the reaction time was 2 h. After one-step leaching, the germanium leaching rate was 61.42%.

[0111] Comparative Example 5

[0112] The raw materials were the same as those used in Example 1;

[0113] Leaching was carried out with a 240 g / L sodium hydroxide aqueous solution. 10 g of raw materials were added, 2 g of sodium sulfite was added, the reaction temperature was controlled at 90 °C, the liquid-solid ratio was 20:1, and the reaction time was 2 h. After one-step leaching, the germanium leaching rate was 54.67%.

[0114] Comparative Example 7

[0115] The raw materials were the same as those used in Example 1;

[0116] Oxygen pressure leaching: 118.2 g of raw materials were added, 1100 ml of 240 g / L sodium hydroxide, the reaction temperature was 180 °C, the reaction time was 4.5 h, and the oxygen partial pressure was 0.45 MPa. After one-step leaching, the germanium leaching rate was 53.02%.

Claims

1. A method for secondary recovery of germanium from low-grade germanium materials, characterized in that; It includes the following steps: Step 1 React the low-grade germanium-containing material with the sub-molten salt medium in a reaction kettle to carry out a sub-molten salt leaching reaction. The sub-molten salt medium contains alkali metal hydroxide; after the reaction is completed, filter and wash to obtain a germanium-containing alkali leaching solution and alkali leaching residue; In Step 1, According to the alkali-ore ratio g:g = 5~20:1, use an alkali with a concentration of 50~90wt%, add a cosolvent in a proportion of 0.2 - 5% of the feeding amount and mix it with the low-grade germanium material. Load the sub-molten salt medium and the low-grade germanium material into the reaction kettle, close the kettle lid, start stirring, introduce an oxygen-containing gas and control the oxygen partial pressure to be 0.05~2.00MPa, control the reaction temperature to be 140~250°C, continuously react for 1~6h, then close the inlet valve, cool down to 80~120°C and keep warm for filtration; Step 2 If the aluminum content in the germanium-containing alkali leaching solution is greater than or equal to 20 mg / L, perform aluminum removal treatment on the germanium-containing alkali leaching solution to obtain aluminum slag and a purified germanium-containing solution; the purified germanium-containing solution passes through an ion exchange column filled with D403 chelating resin to obtain the chelating resin adsorbed with germanium and the alkali solution after germanium extraction; If the aluminum content in the germanium alkali leaching solution is less than 20mg / L, the germanium-containing alkali leaching solution passes through an ion exchange column filled with D403 chelating resin to obtain the chelating resin adsorbed with germanium and the alkali solution after germanium extraction.

2. The method for secondary recovery of germanium from low-grade germanium materials according to claim 1, characterized in that: The germanium content in the low-grade germanium material is 0.1~2.0wt%.

3. A method for secondary recovery of germanium from low-grade germanium materials according to claim 1, characterized in that: In Step 1, control the reaction temperature to be 160 - 180°C.

4. A method for secondary recovery of germanium from low-grade germanium materials according to claim 1, characterized in that: In Step 1, control the rotation speed to be 300~900 revolutions per minute.

5. A method for secondary recovery of germanium from low-grade germanium materials according to claim 1, characterized in that: The oxygen-containing gas includes industrial oxygen; The alkali metal hydroxide is selected from at least one of sodium hydroxide and potassium hydroxide.

6. A method for secondary recovery of germanium from low-grade germanium materials according to claim 1, characterized in that: The sub-molten salt medium includes alkali metal hydroxide or includes alkali metal hydroxide and a cosolvent. The cosolvent is selected from at least one of nitrate, carbonate, and chlorate.

7. A method for secondary recovery of germanium from low-grade germanium materials according to claim 1, characterized in that: Step 1 produces a germanium-containing alkali leaching solution and residue after germanium extraction; the germanium concentration in the germanium-containing alkali leaching solution is 100~2000mg / L, the alkali concentration is 150~250g / L, and the germanium content in the residue after germanium extraction is lower than 400~2000g / t.

8. A method for secondary recovery of germanium from low-grade germanium materials according to claim 1, characterized in that: In Step 2, when the aluminum content in the germanium-containing alkali leaching solution is greater than or equal to 20mg / L, the germanium-containing alkali leaching solution uses a combined aluminum removal agent of sodium silicate and silicon dioxide to precipitate and separate aluminum to obtain aluminum slag and a purified germanium-containing solution; specifically: control the molar ratio of sodium silicate to aluminum in the germanium-containing alkali leaching solution to be 1.5~2.0, react at 140~180°C for 30~120min, age for 24h and then filter to obtain a filter residue with an aluminum content of 5~30% and a purified solution of the germanium alkali leaching solution with an aluminum concentration lower than 20mg / L; In Step 2, the germanium-containing alkaline leaching solution with an aluminum content of less than 20 mg / L passes through an ion exchange column filled with D403 resin at a flow rate of 5-30 BV / h to obtain the resin adsorbed with germanium and the alkaline solution after germanium extraction. The alkaline leaching solution after germanium extraction is evaporated and concentrated and then returned to Step 1 as the sub-molten salt medium; In Step 2, when adsorbing germanium using the ion exchange column of D403 resin, the temperature is controlled at 20-65 °C.

9. A method for secondary recovery of germanium from low-grade germanium materials according to claim 1, wherein: After completing Step 2, the obtained germanium-adsorbed resin is subjected to saturated washing and rinsing, and then eluted with a hydrochloric acid solution to obtain a hydrochloric acid solution containing germanium and the D403 resin after elution; when eluting with the hydrochloric acid solution, germanium adsorbed on the D403 resin is eluted with a hydrochloric acid solution having a concentration of 0.2 to 4.0 mol / L, and the amount of the hydrochloric acid solution used is 2 to 4 m 3 / m 3 -R, the flow rate of the hydrochloric acid solution is 10 to 25 BV / h, and the operating temperature is 20 to 35°C; After obtaining the germanium-containing hydrochloric acid solution, a germanium precipitation aid is added, and the pH value is adjusted to 8.0-10.0 with alkali at room temperature to precipitate germanium. After filtration, a high-grade germanium concentrate with a germanium content of greater than or equal to 20% is obtained.

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