A method for extracting germanium from hard zinc

Abstract

The application discloses a method for extracting germanium from hard zinc, which comprises the following steps: remelting and slagging hard zinc by adding a slagging agent at high temperature to obtain a metal layer and a slag layer; crushing, water immersion, washing and filtering the slag layer to obtain water immersion washing slag and water immersion mixed solution (water immersion liquid and water immersion slag washing liquid); performing acid immersion, washing and filtering on the water immersion washing slag to obtain acid immersion washing slag and acid immersion mixed solution (acid immersion liquid and acid immersion slag washing liquid); performing neutralization reaction on the water immersion mixed solution and the acid immersion mixed solution, filtering to obtain neutralization slag and neutralization liquid, dissolving the neutralization slag in HCl, distilling, hydrolyzing and calcining to obtain GeO2; and returning the neutralization liquid to the water immersion, water immersion slag washing, acid immersion and acid immersion slag washing processes after treatment. The method mainly controls the direction of metal element Ge, realizes effective extraction of Ge, is simple in process flow and easy to operate, has high Ge direct recovery rate and remarkable economic benefits.

Description

Technical Field

[0001] This invention belongs to the field of mining engineering technology, specifically relating to a method for extracting germanium from hard zinc. Background Technology

[0002] Germanium is a typical rare and dispersed element, widely distributed in nature, accounting for approximately 6.7 × 10⁻⁶ of the Earth's crust. −4 Germanium and its compounds are commonly used as semiconductor materials, optical materials, and catalysts, and are widely applied in fields such as fiber optic communication technology, infrared optical materials, solar photovoltaic cells, and organic catalysts. Germanium possesses chemical properties such as lithophile, siderophile, sulfophile, and organophile properties, therefore it cannot form minerals on its own. It mainly occurs as an associated mineral in other minerals, such as lead-zinc mines and coal mines, and is enriched in the smelting slag or byproducts of these metal smelting processes.

[0003] Hard zinc is one of the main raw materials for germanium extraction. In the refining process of crude zinc, the yield of hard zinc accounts for approximately 4% of the crude zinc processed. Before the invention of vacuum distillation to enrich indium and germanium in hard zinc, a flame-insulated furnace-electric furnace process was generally used to recover zinc from hard zinc and enrich rare and dispersed metals such as indium and germanium. The resulting germanium-indium-rich, high-arsenic germanium slag was then subjected to chlorination distillation to recover germanium. This process has the advantage of comprehensively recovering zinc, germanium, and indium, but it also has disadvantages such as low metal recovery rates and production safety issues. Some factories also return hard zinc to smelting to recover lead and zinc, but this method is not conducive to the comprehensive recovery of metals such as germanium, indium, and silver. Other factories use additives to separate zinc and iron from hard zinc, but this does not consider the comprehensive recovery of other metals. The traditional process for processing hard zinc in my country is the indirect flame furnace method. Its basic principle is to utilize the differences in boiling points among the elements in hard zinc. Hard zinc is heated to 910℃~920℃ using coal or gas, causing the zinc to volatilize and then rapidly cooled to obtain ultrafine zinc powder. Other high-boiling-point elements such as lead, iron, germanium, and indium remain in the distillation residue and are periodically discharged to an electric furnace for recovery of rare metals such as germanium and indium. The indirect flame furnace method has the advantages of being a mature and stable process, but it also has disadvantages such as high energy consumption, a large amount of intermediate products leading to dispersion of germanium, indium, and silver, resulting in low recovery rates. The direct recovery rate of germanium is only 60%. Zheng Shunde et al. used a method of melting and de-leading hard zinc, casting it into anodes, and then electrolyzing it to process hard zinc. Valuable elements such as germanium, indium, and silver are enriched in the anode mud. However, this method is limited in its widespread application due to high cost, the need to add sodium chloride as an additive to the electrolyte, and the high corrosion resistance requirements of the equipment. Currently, the most widely adopted method for treating hard zinc is vacuum distillation. This involves adding hard zinc to a sealed, horizontal vacuum furnace and heating it electrically. This causes the low-boiling-point zinc to volatilize into the gas phase, while the high-boiling-point germanium, indium, and silver remain in the vacuum slag. The germanium in the slag is then recovered through a chlorination leaching and distillation process using chlorine as an oxidant in concentrated hydrochloric acid. However, this process suffers from drawbacks such as low germanium recovery rate, difficulty in controlling the amount of chlorine added, operational safety concerns, and high concentrations of distilled hydrochloric acid. Therefore, developing a method that addresses these technical problems is essential. Summary of the Invention

[0004] The purpose of this invention is to provide a method for extracting germanium from hard zinc. This method mainly controls the orientation of the metallic element Ge to achieve efficient Ge extraction. The process is simple and easy to operate, with a high direct recovery rate of Ge and significant economic benefits. This invention involves remelting hard zinc with a slag-forming agent at high temperature to form slag, resulting in a metal layer and a slag layer. The slag layer is then crushed, water-leached, washed, and filtered to obtain water-leached slag and a water-leached mixed solution (water-leached liquid and water-leached slag washing liquid). The water-leached slag is then acid-leached, washed, and filtered to obtain acid-leached slag and an acid-leached mixed solution (acid-leached liquid and acid-leached slag washing liquid). After neutralization of the water-leached mixed solution and the acid-leached mixed solution, the mixture is filtered to obtain neutralized slag and neutralized liquid. The neutralized slag is dissolved in HCl, distilled, and hydrolyzed to obtain GeO2. The neutralized liquid is then treated and returned to the water-leaching, water-leached slag washing, acid-leaching, and acid-leached slag washing processes.

[0005] The objective of this invention is achieved by including pretreatment, water immersion, acid immersion, and post-treatment steps, specifically including: A. Pre-processing: 1) Add slag-forming agent to hard zinc and remelt to separate slag and obtain metal layer a and slag b; metal layer a is zinc alloy; 2) The molten slag b is crushed to obtain material c; B. Water immersion: Add 1 to 20 times the volume of water to material c (solid-liquid ratio), stir and immerse in water at 10 to 300°C for 0.5 to 10 hours, filter and wash to obtain water-immersed residue d and water-immersed mixture e; water-immersed mixture e consists of water-immersed liquid and water-immersed residue washing liquid. C. Acid leaching: Add acid of 2 to 20 times the solid-liquid volume of water-leached residue d to the water-leached residue d, stir and acid leaching at a temperature of 10 to 300℃ for 0.5 to 10 hours, filter and wash to obtain acid-leached residue f and acid-leached mixture g; the acid-leached mixture g is composed of acid-leached liquid and acid-leached residue washing liquid. D. Post-processing: Neutralize the water leaching mixture e and the acid leaching mixture g, and filter to obtain neutralization residue h and neutralization liquid i; return neutralization liquid i to the previous step; neutralization residue h is dissolved in hydrochloric acid, distilled, and hydrolyzed to obtain GeO2 and hydrolysate, and the hydrolysate is returned to the previous step.

[0006] Germanium in hard zinc exists in the form of a zinc-germanium alloy.

[0007] When hard zinc is calcined at high temperature with the addition of a slagging agent (alkali or alkaline earth hydroxide), germanium gradually floats to the surface of the melt in the form of oxides, and some of it reacts with the slagging agent to form germanates. Ge + O2 → GeO2; GeO2 + 2NaOH → Na2GeO3 + H2O.

[0008] Water leaching of molten slag: Na2GeO3 is soluble in aqueous solution.

[0009] Acid leaching of water residue: GeO2, which is insoluble in alkali, dissolves in HCl to form GeCl4.

[0010] GeO2 + 4HCl → GeCl4 + 2H2O; GeCl4 hydrolyzes to form GeO2 at pH greater than 2.5, GeCl4 + 2H2O → GeO2 + 4HCl.

[0011] Aqueous and acidic leaching solutions also neutralize to form GeO2. Alkaline Na2GeO3 solution reacts with acidic GeCl4 solution to form GeO2 and NaCl. Na2GeO3 + 2HCl → GeO2 + 2NaCl + H2O. During neutralization, NaOH + HCl → NaCl + H2O. As pH increases during neutralization, GeCl4 hydrolyzes: GeCl4 + 2H2O → GeO2 + 4HCl.

[0012] The specific steps are as follows: 1. Hard zinc and slag-forming agent are added to the furnace for remelting and slag formation. The amount of slag-forming agent is 0.1 to 20 times the weight of hard zinc. The remelting and slag formation temperature is 420℃ to 900℃, and the maximum temperature residence time is 30 min to 10 h.

[0013] 2. After slag formation, separate the metal layer and the slag layer. The metal layer without Ge is used for other purposes. The slag layer is mixed with an aqueous solution and then wet-milled, ball-milled, rod-milled, or sand-milled, requiring a particle size of -200 mesh > 85%.

[0014] 3. Pour out the finely ground slurry and immerse it in water in an alkali-resistant reaction device. The water immersion process conditions are as follows: water immersion temperature from room temperature to 300℃, liquid-solid ratio of 1:1 to 20:1, time of 0.5 to 10 hours, mechanical stirring speed of 20 r / min to 1000 r / min, and pressurized water immersion is preferred.

[0015] 4. After the water immersion is completed, filter and wash to obtain water immersion residue and water immersion mixture (water immersion liquid and water immersion residue washing liquid).

[0016] 5. Place the water-leached residue into an acid-resistant reaction device, and pour in the prepared H2SO4, HNO3, or HCl acid solution for acid leaching. The acid leaching conditions are: leaching temperature room temperature to 300℃, leaching time 0.5 to 10 hours, mechanical stirring speed 20 r / min to 1000 r / min, final pH value < 1, leaching liquid-to-solid ratio 2:1 to 20:1, and pressurized acid leaching is preferred.

[0017] 6. After acid leaching, filter and wash to obtain acid leaching residue and acid leaching mixture (acid leaching solution and acid leaching residue washing solution). The pH value of the acid leaching washing solution is less than 2.5, and the washing solution is prepared with the same acid as that used in the acid leaching process.

[0018] 7. After acid leaching, the aqueous leaching solution and the acid leaching solution are neutralized and precipitated, and the pH value of the neutralization reaction is controlled at 2~10.

[0019] 8. After neutralization, filter to obtain neutralized residue and neutralized filtrate.

[0020] 9. Dissolve the neutralization residue with an HCl solution of 0.1% to 37% by mass, and then separate the GeCl4 layer solution.

[0021] 10. The GeCl4 solution was distilled at 83℃~100℃ to obtain volatiles and water. The water was used to prepare an HCl solution, and the volatiles were dissolved in ultrapure water for hydrolysis to extract GeO2.

[0022] 11. After hydrolysis, filter the solution. Return the filtrate to prepare HCl solution. Wash and dry the filter residue before storing it.

[0023] 12. The anion in the neutralization solution is SO42-.2- After adding CaO for causticization, the mixture is returned to the crushing, water immersion, and water immersion residue washing processes; the anion in the neutralization solution is NO3. - and Cl - After evaporation concentration or reverse osmosis treatment, the treated water can be used in all water-using processes. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the process flow of the present invention; Figure 2 This is a schematic diagram showing the appearance of the melt in the crucible during high-temperature slag-forming smelting. Figure 3 This is a schematic diagram showing the appearance of the melt in the crucible after slag-forming smelting and cooling. Figure 4 This is a schematic diagram of the zinc alloy separated after slag-forming smelting. Figure 5 This is a schematic diagram of the slag blocks separated after slag-making and smelting. Detailed Implementation

[0025] The present invention will be further described below with reference to embodiments, but this is not intended to limit the present invention in any way. Any modifications or substitutions made based on the teachings of the present invention shall fall within the protection scope of the present invention.

[0026] The method for extracting germanium from hard zinc according to the present invention includes pretreatment, water immersion, acid immersion and posttreatment steps, specifically including: A. Pre-processing: 1) Add slag-forming agent to hard zinc and remelt to separate slag and obtain metal layer a and slag b; metal layer a is zinc alloy; 2) The molten slag b is crushed to obtain material c; B. Water immersion: Add 1 to 20 times the volume of water to material c (solid-liquid ratio), stir and immerse in water at 10 to 300°C for 0.5 to 10 hours, filter and wash to obtain water-immersed residue d and water-immersed mixture e; water-immersed mixture e consists of water-immersed liquid and water-immersed residue washing liquid. C. Acid leaching: Add acid of 2 to 20 times the solid-liquid volume of water-leached residue d to the water-leached residue d, stir and acid leaching at a temperature of 10 to 300℃ for 0.5 to 10 hours, filter and wash to obtain acid-leached residue f and acid-leached mixture g; the acid-leached mixture g is composed of acid-leached liquid and acid-leached residue washing liquid. D. Post-processing: Neutralize the water leaching mixture e and the acid leaching mixture g, and filter to obtain neutralization residue h and neutralization liquid i; return neutralization liquid i to the previous step; neutralization residue h is dissolved in hydrochloric acid, distilled, and hydrolyzed to obtain GeO2 and hydrolysate, and the hydrolysate is returned to the previous step.

[0027] The slag-forming agent is one or more of NaOH, KOH, LiOH, Ca(OH)2, Mg(OH)2, Na2CO3, and K2CO3.

[0028] The amount of the slag-forming agent is 0.1 to 20 times the mass of hard zinc.

[0029] The remelting and slag-forming temperature is 420~900℃, and the time is 0.5~10h.

[0030] The required particle size for crushing is -200 mesh > 85%.

[0031] In step B, the stirring speed is 20~1000 r / min.

[0032] The acid in step C is H2SO4, HNO3, or HCl.

[0033] The acid mentioned is H2SO4.

[0034] In step C, the stirring speed is 20~1000 r / min.

[0035] Both water leaching and acid leaching steps are carried out under a pressure of 1~5 Pa.

[0036] The invention will be further illustrated below with specific implementation examples: Example 1 1. Hard zinc and slag-forming agent are added to the furnace for remelting and slag formation, with 1000g of hard zinc and 0.40 times the weight of NaCO3 slag-forming agent. The remelting and slag formation temperature is 870℃ and the maximum temperature residence time is 2h.

[0037] 2. After slag formation, separate the metal layer and the slag layer. Take 200g of the slag layer, add it to 500ml of aqueous solution, and wet ball mill for 2 hours. After ball milling, separate the balls and slurry using a 200-mesh sieve.

[0038] 3. The slurry is poured into a glass reactor for water immersion. The water immersion process conditions are: temperature 90℃, liquid-to-solid ratio 5:1, time 2h, and mechanical stirring speed 400r / min.

[0039] 4. After water immersion, filter to separate the residue and liquid. The residue is then washed at 85℃ with 1L of pretreated neutralized liquid for 1 hour (repeated twice) to obtain water-immersion residue and water-immersion mixture (water immersion liquid and water immersion residue washing liquid).

[0040] 5. Place the water-leached residue into an acid-resistant autoclave, and pour in the prepared 200g / L H2SO4 solution for acid leaching. The acid leaching conditions are: leaching temperature 160℃, time 2h, mechanical stirring speed 400r / min, pH value at the leaching endpoint <1, and leaching liquid-to-solid ratio 5:1.

[0041] 6. After acid leaching, filter to separate the residue and liquid. The residue is then washed at 85℃ with 1L of washing solution with a pH value less than 2.5 for 1 hour (repeated twice) to obtain acid leaching residue and acid leaching mixture (acid leaching solution and acid leaching residue washing solution).

[0042] 7. After acid leaching, the water leaching solution and acid leaching solution are neutralized and precipitated, and the pH value of the neutralization reaction is controlled at 3.

[0043] 8. After neutralization, filter to obtain neutralization residue and neutralization filtrate.

[0044] 9. Dissolve the neutralization residue with a 5% (w / w) HCl solution, and then separate the GeCl4 layer solution.

[0045] 10. The GeCl4 solution was distilled at 85°C to obtain volatiles and water. The water was used to prepare an HCl solution, and the volatiles were dissolved in ultrapure water for hydrolysis to extract GeO2.

[0046] 11. After hydrolysis, filter the solution. Return the filtrate to prepare HCl solution. Wash and dry the filter residue before storing it.

[0047] 12. The anion in the neutralization solution is SO42-. 2- After adding CaO for causticization, the mixture is returned to the crushing, water immersion, and water immersion residue washing process.

[0048] Germanium was extracted according to the above operating steps. The Ge content in the metal layer was less than 0.01%, and the total germanium leaching rate reached 91%.

[0049] Example 2 1. Hard zinc and slag-forming agent are added to the furnace for remelting and slag formation, with 1000g of hard zinc and 0.20 times the weight of NaOH slag-forming agent. The remelting and slag formation temperature is 600℃ and the maximum temperature residence time is 1h.

[0050] 2. After slag formation, separate the metal layer and the slag layer. Take 200g of the slag layer, add it to 500ml of aqueous solution, and wet ball mill for 2 hours. After ball milling, separate the slurry and balls using a 200-mesh sieve.

[0051] 3. Pour the slurry into an alkali-resistant autoclave for water immersion. The water immersion process conditions are: temperature 150℃, liquid-to-solid ratio 5:1, time 2h, and mechanical stirring speed 400r / min.

[0052] 4. After water immersion, filter to separate the residue and liquid. The residue is then washed at 85℃ with 1L of pretreated neutralized liquid for 1 hour (repeated twice) to obtain water-immersion residue and water-immersion mixture (water immersion liquid and water immersion residue washing liquid).

[0053] 5. Place the water-leached residue into an acid-resistant autoclave, and pour in the prepared 300g / L H2SO4 solution for acid leaching. The acid leaching conditions are: leaching temperature 150℃, time 2h, mechanical stirring speed 400r / min, pH value at the leaching endpoint <1, and leaching liquid-to-solid ratio 5:1.

[0054] 6. After acid leaching, filter to separate the residue and liquid. The residue is then washed at 85℃ with 1L of washing solution with a pH value less than 2.5 for 1 hour (repeated twice) to obtain acid leaching residue and acid leaching mixture (acid leaching solution and acid leaching residue washing solution).

[0055] 7. After acid leaching, the water leaching solution and acid leaching solution are neutralized and precipitated, and the pH value of the neutralization reaction is controlled at 3.

[0056] 8. After neutralization, filter to obtain neutralization residue and neutralization filtrate.

[0057] 9. The neutralization residue is dissolved in a 10% (w / w) HCl solution, and the GeCl4 layer solution is separated after dissolution.

[0058] 10. The GeCl4 solution was distilled at 85°C to obtain volatiles and water. The water was used to prepare an HCl solution, and the volatiles were dissolved in ultrapure water for hydrolysis to extract GeO2.

[0059] 11. After hydrolysis, filter the solution. Return the filtrate to prepare HCl solution. Wash and dry the filter residue before storing it.

[0060] 12. The anion in the neutralization solution is SO42-. 2- After adding CaO for causticization, the mixture is returned to the crushing, water immersion, and water immersion residue washing process.

[0061] Germanium was extracted according to the above operating steps. The Ge content in the metal layer was less than 0.001%, and the total germanium leaching rate reached 93%.

Claims

1. A method for extracting germanium from hard zinc, characterized in that, It includes pretreatment, water immersion, acid immersion, and post-treatment steps, specifically including: A. Pre-processing: 1) Add one or more of the following slag-forming agents to hard zinc: NaOH, KOH, LiOH, Ca(OH)2, Mg(OH)2, Na2CO3, and K2CO3. Remelt and slag form at 600~900℃ for 0.5~10h. After remelting, separate the metal layer a and slag b. The metal layer a is a zinc alloy. 2) The molten slag b is crushed to obtain material c, and the particle size requirement is -200 mesh > 85%; B. Water immersion: Add 1 to 20 times the volume of solid material c to material c, stir and immerse in water at a temperature of 10 to 300℃ for 0.5 to 10 hours, filter and wash to obtain water immersion residue d and water immersion mixture e; water immersion mixture e consists of water immersion liquid and water immersion residue washing liquid. C. Acid leaching: Add acid of 2 to 20 times the solid volume of water-leached residue d to the water-leached residue d, stir and leach at a temperature of 10 to 300℃ for 0.5 to 10 hours. The pH value at the leaching endpoint is <1. Filter and wash to obtain acid-leached residue f and acid-leached mixture g. The acid-leached mixture g is composed of acid-leached solution and acid-leached residue washing solution. D. Post-processing: Neutralize the water leaching mixture e and the acid leaching mixture g, and filter to obtain neutralized residue h and neutralized liquid i; neutralized liquid i is returned to the water leaching step to wash the water leaching residue d; neutralized residue h is dissolved in hydrochloric acid, distilled and hydrolyzed to obtain GeO2 and hydrolysate, and the hydrolysate is returned to the acid leaching step.

2. The method for extracting germanium from hard zinc according to claim 1, characterized in that, The amount of the slag-forming agent is 0.1 to 20 times the mass of hard zinc.

3. The method for extracting germanium from hard zinc according to claim 1, characterized in that, In step B, the stirring speed is 20~1000 r / min.

4. The method for extracting germanium from hard zinc according to claim 1, characterized in that, The acid in step C is H2SO4, HNO3, or HCl.

5. The method for extracting germanium from hard zinc according to claim 4, characterized in that, The acid mentioned is H2SO4.

6. The method for extracting germanium from hard zinc according to claim 1, characterized in that, In step C, the stirring speed is 20~1000 r / min.

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