A method for comprehensive recovery and utilization of residual liquid from germanium chloride distillation of germanium concentrate

Abstract

This invention discloses a method for the comprehensive recovery and utilization of germanium concentrate chloride distillation residue, belonging to the field of hydrometallurgical technology. The invention includes the following steps: secondary distillation of germanium distillation residue; germanium-containing hydrochloric acid fraction is used to absorb the fraction and tail gas from sulfation evaporation; antimony is selectively recovered by precipitation of mother liquor; calcium is removed by sulfate treatment after antimony precipitation, and iron is removed by lead-oxidation neutralization; calcium-iron slag is outsourced for treatment; zinc-containing solution is concentrated by direct evaporation of the iron-removed liquid; zinc sulfate crystallization mother liquor or concentrated sulfuric acid is slowly added to the concentrated mother liquor; the fraction and tail gas at this time are absorbed by the fraction of secondary distillation of residue to produce high-concentration hydrochloric acid, which is returned to germanium concentrate distillation; after a large amount of turbidity appears in the mother liquor, acid addition and evaporation are stopped; after cooling, liquid-solid separation filtrate is returned to the concentrated mother liquor sulfation evaporation crystallization process; the filter cake is washed with saturated zinc sulfate and dried to obtain industrial zinc sulfate; the wash water can be recycled multiple times and added to the filtrate. This invention solves the problems of high corrosiveness of direct filtration of germanium distillation residue, consumption of neutralizing agent by residual free HCl, lack of antimony recovery, high cost of preparing concentrated hydrochloric acid solution from medium concentration hydrochloric acid solution, and difficulty in opening circuits for alkali metal ions in solution.

Description

Technical Field

[0001] This invention belongs to the field of chemical technology, specifically relating to a method for the comprehensive recovery and utilization of residual liquid from the chlorination of germanium concentrate. Background Technology

[0002] Germanium is a strategic national resource, playing a vital role in national defense, aerospace, and daily life. The extraction of germanium from germanium concentrate produces a large amount of highly acidic distillation liquor containing numerous and complex valuable components (hydrochloric acid, germanium, zinc, antimony, etc.). The mainstream process uses neutralization combined with evaporation and crystallization to remove harmful elements from the liquor and ensure compliant wastewater discharge, generating substantial amounts of hazardous waste requiring treatment. This results in low overall recovery rates of valuable elements and significant environmental pressure for germanium concentrate smelting enterprises. Furthermore, the treatment of distillation liquor negatively impacts the overall efficiency of the germanium smelting process. Developing a comprehensive recovery and utilization process for valuable components in distillation liquor is of great significance for improving both the economic and environmental benefits of germanium concentrate smelting. Summary of the Invention

[0003] The purpose of this invention is to provide a method for the comprehensive recovery and utilization of residual liquid from the chloride distillation of germanium concentrate.

[0004] The objective of this invention is achieved as follows: the method for comprehensive recovery and utilization of germanium concentrate chloride distillation residue includes secondary distillation, antimony precipitation, calcium and lead removal, iron removal, and post-treatment steps, specifically including: A. Secondary distillation: The residual liquid from the germanium chloride distillation of germanium concentrate is used to continue distillation to obtain mother liquor a and fraction b. B. Antimony precipitation: A neutralizing agent is added to distillation mother liquor a to select antimony precipitation, and liquid-solid separation is performed to obtain high-antimony slag c and antimony-precipitated liquid d. C. Calcium and lead removal: Sulfate is added to the antimony precipitation solution to remove calcium and lead, yielding material e; D. Iron removal: Oxidizing agent and neutralizing agent are added to material e to remove iron. Liquid-solid separation yields iron removal liquid f and calcium-iron slag g. E. Post-processing: 1) After iron removal, the liquid f is concentrated by evaporation and sulfation evaporation to obtain fraction h and mother liquor i; fraction h and fraction b are combined and absorbed to prepare concentrated hydrochloric acid, which is then returned to germanium concentrate distillation. 2) After cooling the mother liquor i, filter to separate filtrate j and filter cake k; return the filtrate to step C for recycling; wash the filter cake with saturated zinc sulfate solution to obtain zinc sulfate, and the washing solution is recycled multiple times and then added to the filtrate for recycling.

[0005] The specific steps are as follows: (1) Secondary distillation of the germanium residue; (2) The fraction produced in step (1) is used to absorb the fraction and tail gas from the sulfation evaporation; (3) Add a neutralizing agent to the distillation mother liquor produced in step (1) to select antimony precipitation, and after liquid-solid separation, obtain high antimony slag and antimony precipitation liquid; (4) The antimony-precipitated liquid produced in step (3) is first treated with sulfate to remove calcium, and then a neutralizing agent and an oxidizing agent are added to remove impurities such as calcium and iron from the solution. The calcium and iron slag is then outsourced for processing. (5) The iron-removed liquid produced in step (4) is directly evaporated and concentrated; (6) The concentrated liquid produced in step (5) is further evaporated and zinc sulfate crystallization mother liquor or concentrated sulfuric acid is added for sulfation and evaporation. The distillate and tail gas are absorbed by the germanium-containing hydrochloric acid distillate produced in step (1) to prepare concentrated hydrochloric acid, and then returned to the germanium concentrate distillation. (7) The turbid distillation mother liquor produced in step (6) is cooled and filtered to separate it. The filtrate is returned to step (4) for sulfation evaporation. The filter cake is washed with saturated zinc sulfate and then dried to obtain industrial zinc sulfate. The wash water can be recycled multiple times and then added to the filtrate.

[0006] In the above-mentioned method for comprehensive recycling of germanium distillation residue, in step (1), the germanium distillation residue is distilled twice. This is done by taking advantage of the fact that the temperature of the residue is still very high and close to the boiling point of the solution. Continuing to distill can volatilize the residual germanium and free HCl into the distillate. The endpoint of evaporation and crystallization can be determined by the temperature of the mother liquor. Different sources of germanium concentrate may result in different temperatures at the endpoint of the concentrated mother liquor.

[0007] In the above-mentioned method for comprehensive recycling of germanium distillation residue, in step (3), a neutralizing agent is added to the distillation mother liquor to precipitate antimony. The neutralizing agent used is soluble, such as (NaOH, KOH, Na2CO3, etc.), preferably NaOH, because neutralizing the same acid introduces less sodium ions. Carbonates may form precipitates with some cations in the solution during neutralization, which may affect the grade of high antimony slag. The pH of the antimony precipitation process is controlled at 1.5-3.0, preferably 2.0-2.5, the temperature is 30-80℃, and the precipitation reaction time is 10-180min, preferably 30-90min.

[0008] In the above-mentioned method for comprehensive recycling of germanium distillation residue, in step (4), sulfate is first added to the antimony-precipitated liquid to remove calcium, and then a neutralizing agent and an oxidizing agent are added to remove impurities such as calcium and iron from the solution. The calcium and iron slag is outsourced for treatment. The added sulfate is zinc sulfate, and the amount added is 0.8-1.5 times the theoretical amount of calcium to be removed. The neutralizing agent in the iron removal process is limestone, quicklime or hydrated lime, and the added oxidizing agent is 1.2-3.0 times the theoretical amount of iron to be removed. It can be air, oxygen, hydrogen peroxide, etc. The process is controlled at pH 4.5-5.0, and the temperature is controlled to match the antimony precipitation process.

[0009] In the above-mentioned method for comprehensive recycling of germanium evaporation residue, in step (5), the liquid after iron removal is directly evaporated and concentrated. The liquid after iron removal has a pH of about 5.0 and a lower boiling point than the liquid after acid addition. The evaporation and concentration speed is fast, and the distillate produced has a very low content of neutral impurities. The concentration ends when the mother liquor becomes turbid, at which point sulfation evaporation begins.

[0010] In the above-mentioned method for comprehensive recycling of germanium distillation residue, in step (6), the concentrate continues to evaporate and zinc sulfate crystallization mother liquor or concentrated sulfuric acid is added for sulfation evaporation. The distillate and tail gas are absorbed by the germanium-containing hydrochloric acid distillate produced in step (1) to prepare concentrated hydrochloric acid, which is then returned to germanium concentrate distillation. The total amount of sulfuric acid added is 10%-30% of the liquid volume after iron removal, ensuring that the sulfuric acid concentration in the crystallization mother liquor is higher than 600g / L. At this time, the chlorine in the solution is basically completely volatilized, and the solution is in a boiling state during the evaporation process. The absorption of the distillate and tail gas can be carried out by single-stage or multi-stage absorption, which will meet the requirements of germanium concentrate distillation for hydrochloric acid concentration and be returned for reuse.

[0011] In the above-mentioned method for comprehensive recycling of germanium distillation residue, in step (7), the turbid distillation mother liquor is cooled and filtered for separation. The filtrate is returned to step (4) for sulfation evaporation. The filter cake is washed with saturated zinc sulfate and then dried to obtain industrial zinc sulfate. The wash water can be recycled multiple times and then added to the filtrate. After the evaporation and crystallization stop, the temperature is high and the solubility of zinc sulfate is high. Appropriate cooling can increase the recovery rate of zinc sulfate and reduce the operational safety risk. The filtrate contains a large amount of sulfuric acid. Returning it to the concentrate for acidification evaporation can reduce the consumption of sulfuric acid and avoid the discharge of waste liquid. Industrial zinc sulfate will remove some alkali metal salts and some harmful elements. Because the zinc content is very high, the content of these entrained elements has no effect on the requirements of industrial zinc sulfate, thus achieving the open-circuit balance of alkali metal ions in the solution.

[0012] The technical solution of this invention is mainly based on the following principles: Secondary distillation of the germanium residue can reduce heat consumption by utilizing its still high temperature state; free HCl and Ge will enter the distillate during evaporation, reducing alkali consumption during antimony precipitation; antimony hydrolysis has a low pH, and by controlling the pH to a low level, antimony can be separated from complex solution systems to produce high-antimony slag mainly composed of antimony oxychloride. Too low a pH will reduce the antimony recovery rate, while too high a pH will cause a large amount of iron to hydrolyze and precipitate, affecting the grade of the high-antimony slag; utilizing the low solubility of calcium sulfate, adding zinc sulfate produced by sulfation evaporation crystallization to the antimony precipitation liquid can remove most of the calcium and a small amount of magnesium along with iron, reducing the calcium content in the zinc sulfate; direct evaporation and concentration of the liquid after iron removal is due to the low boiling point of the solution at this time, resulting in low evaporation and concentration costs. The evaporation of water in the solution also helps to increase the concentration of the absorption distillate and hydrochloric acid produced by the tail gas during sulfation evaporation; under suitable evaporation temperature and sulfuric acid dosage, all chlorine in the solution can be volatilized, and the concentration of some soluble cations in the solution is lower than that of zinc, thus producing qualified industrial zinc sulfate.

[0013] Compared with the prior art, the advantages of the present invention are as follows: (1) The residual liquid of germanium distillation is distilled twice, which realizes the recovery of free HCl, reduces the consumption of neutralizing agent, and the distillate is used to absorb the distillate of sulfation evaporation and tail gas to prepare high-concentration hydrochloric acid. The cost is lower than the existing dilute hydrochloric acid concentration process. (2) Adding a neutralizing agent to the distillation mother liquor to selectively precipitate antimony, producing high-antimony slag, thereby realizing the recovery and utilization of antimony and its separation and removal from the solution; (3) After antimony precipitation, sulfate is added to remove calcium, which can reduce the calcium content in industrial zinc sulfate and help ensure its quality. The added sulfate is the produced zinc sulfate. After adding it, the zinc ion concentration can be increased, which is also beneficial to improving the quality of zinc sulfate. (4) After removing iron, the liquid is first evaporated and concentrated, and then sulfated and evaporated. This can reduce heat consumption and help increase the hydrochloric acid concentration of the acidified evaporation absorption distillate solution. (5) The zinc sulfate produced by sulfation evaporation crystallization will carry away some alkali metal ions and other impurity elements from the mother liquor, thus achieving an open-circuit balance between alkali metal elements and other impurity elements in the germanium evaporation residue. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the process flow of the present invention. Detailed Implementation

[0015] 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.

[0016] The method for comprehensive recovery and utilization of germanium concentrate chloride distillation residue as described in this invention includes secondary distillation, antimony precipitation, calcium and lead removal, iron removal, and post-treatment steps, specifically including: A. Secondary distillation: The residual liquid from the germanium chloride distillation of germanium concentrate is used to continue distillation to obtain mother liquor a and fraction b. B. Antimony precipitation: A neutralizing agent is added to distillation mother liquor a to select antimony precipitation, and liquid-solid separation is performed to obtain high-antimony slag c and antimony-precipitated liquid d. C. Calcium and lead removal: Sulfate is added to the antimony precipitation solution to remove calcium and lead, yielding material e; D. Iron removal: Oxidizing agent and neutralizing agent are added to material e to remove iron. Liquid-solid separation yields iron removal liquid f and calcium-iron slag g. E. Post-processing: 1) After iron removal, the liquid f is concentrated by evaporation and sulfation evaporation to obtain fraction h and mother liquor i; fraction h and fraction b are combined and absorbed to prepare concentrated hydrochloric acid, which is then returned to germanium concentrate distillation. 2) After cooling the mother liquor i, filter to separate filtrate j and filter cake k; return the filtrate to step C for recycling; wash the filter cake with saturated zinc sulfate solution to obtain zinc sulfate, and the washing solution is recycled multiple times and then added to the filtrate for recycling.

[0017] The neutralizing agent mentioned in step B is NaOH or Na2CO3.

[0018] In step B, the pH value for antimony precipitation is controlled between 1.5 and 3.0.

[0019] In step B, the temperature for antimony precipitation is controlled between 30 and 80°C.

[0020] The reaction time for antimony precipitation in step B is 10~180 min.

[0021] The sulfate mentioned in step C is zinc sulfate, and the amount added is 0.8 to 1.5 times the theoretical amount of calcium to be removed.

[0022] The oxidant mentioned in step D is air, oxygen, or hydrogen peroxide, and the amount added is 1.2 to 3.0 times the theoretical amount for iron removal.

[0023] The neutralizing agent mentioned in step D is limestone, quicklime, or slaked lime.

[0024] Step 1) involves directly evaporating and concentrating the iron-removed liquid f. The concentration ends when the mother liquor becomes turbid, at which point sulfation evaporation begins. The sulfation evaporation mentioned above involves adding zinc sulfate crystallization mother liquor or concentrated sulfuric acid for sulfation evaporation.

[0025] The invention will be further illustrated below with specific implementation examples: Example 1 The composition of the germanium distillation residue is shown in Table 1.

[0026] Table 1. Components of germanium distillation residue

[0027] 1) Double distillation Take 1000 mL of germanium distillation residue and perform a second distillation at the boiling point. Stop evaporation and cool down when the mother liquor temperature reaches 125℃. The mother liquor and fraction data are shown in Table 2.

[0028] Table 2 Secondary distillation data A small amount of rinsing water was mixed into the mother liquor, and some volatiles were not completely condensed during the experiment and directly entered the air, resulting in a certain deviation in the volatility rate calculated by the distillate and the mother liquor.

[0029] 2) Selection of antimony precipitation in mother liquor Take 590 mL of the entire mother liquor, add NaOH at 60℃ to adjust the pH to 2.5, stir and react for 60 min. The composition analysis of the high antimony slag and the antimony-precipitated liquid is shown in Table 3.

[0030] Table 3. Components of high-antimony slag and antimony-precipitated liquid 3) Removal of calcium and lead from antimony precipitation solution Take 500 mL of the solution after antimony precipitation. At 60℃, first add 77.02 g of zinc sulfate heptahydrate, 1.2 times the theoretical amount for removing calcium and lead. After stirring and dissolving, add limestone to adjust the pH of the solution to 5.0. Then, add the solution according to the Fe content... 2+ Add 1.5 mL of hydrogen peroxide (1.5 times the theoretical amount) to the solution, adjust the pH of the system to 5.0, and stir for 60 min. The liquid composition after iron removal is shown in Table 4.

[0031] Table 4. Composition of liquid after iron removal 4) Concentrate the iron-removed solution and then crystallize it by sulfation. Take 400 mL of the iron-removed liquid and directly evaporate 200 mL of the distillate. The solution becomes obviously turbid, and the pH of the distillate is 6.5-7.0. Slowly add concentrated sulfuric acid. As more acid is added, more and more crystals appear in the solution. White crystals are at the bottom of the round-bottom flask and clear liquid is at the top. After adding 100 mL of concentrated sulfuric acid, stop adding acid and allow it to cool naturally to below 80°C before liquid-solid separation. After taking out the filtrate, wash it three times with saturated zinc sulfate solution to obtain industrial-grade zinc sulfate. Its composition is shown in Table 5.

[0032] Table 5 Zinc sulfate standards and experimentally prepared zinc sulfate components

[0033] Through secondary evaporation of germanium residue, antimony is precipitated in the mother liquor. After antimony precipitation, zinc sulfate is used to remove calcium and lead, and iron is removed by oxidation neutralization. After iron removal, the liquid is first evaporated and concentrated, then sulfated and evaporated to crystallize. The filter cake is saturated with zinc sulfate and washed to produce qualified industrial zinc sulfate.

Claims

1. A method for comprehensive recovery and utilization of residual liquid from germanium chloride distillation of germanium concentrate, characterized in that, The method includes secondary distillation, antimony precipitation, calcium and lead removal, iron removal, and post-treatment steps, specifically including: A. Secondary distillation: The residual liquid from the chloride distillation of germanium concentrate is subjected to secondary distillation at the boiling point to obtain mother liquor a and fraction b; B. Antimony precipitation: A neutralizing agent is added to the mother liquor a to precipitate antimony, and liquid-solid separation is performed to obtain high-antimony slag c and antimony-precipitated liquid d; C. Removal of calcium and lead: Sulfate is added to the antimony-precipitated liquid d to obtain material e containing calcium and lead precipitate; D. Iron removal: Oxidizing agent and neutralizing agent are added to material e to remove iron, and liquid-solid separation is performed to obtain iron removal liquid f and calcium-iron slag g. E. Post-processing: 1) The iron-removing liquid f is successively evaporated and concentrated and then sulfated and evaporated to obtain fraction h and mother liquor i; fraction b is used as an absorbent to absorb fraction h and tail gas to prepare concentrated hydrochloric acid, and the prepared concentrated hydrochloric acid is returned to the germanium concentrate distillation step for use. 2) After cooling the mother liquor i, filter and separate it to obtain filtrate j and filter cake k; filtrate j is returned to step C for calcium and lead removal; filter cake k is washed with saturated zinc sulfate solution to obtain zinc sulfate, and the washing solution is recycled multiple times and then added to filtrate j.

2. The method for comprehensive recovery and utilization of germanium concentrate chloride distillation residue as described in claim 1, characterized in that, The neutralizing agent mentioned in step B is NaOH or Na2CO3.

3. The method for comprehensive recovery and utilization of germanium concentrate chloride distillation residue as described in claim 1, characterized in that, In step B, the pH value for antimony precipitation is controlled between 1.5 and 3.

0.

4. The method for comprehensive recovery and utilization of germanium concentrate chloride distillation residue as described in claim 1, characterized in that, In step B, the temperature for antimony precipitation is controlled between 30 and 80°C.

5. The method for comprehensive recovery and utilization of germanium concentrate chloride distillation residue as described in claim 1, characterized in that, The reaction time for antimony precipitation in step B is 10~180 min.

6. The method for comprehensive recovery and utilization of germanium concentrate chloride distillation residue as described in claim 1, characterized in that, The sulfate mentioned in step C is zinc sulfate, and the amount added is 0.8 to 1.5 times the theoretical amount of calcium to be removed.

7. The method for comprehensive recovery and utilization of germanium concentrate chloride distillation residue as described in claim 1, characterized in that, The oxidant mentioned in step D is air, oxygen, or hydrogen peroxide, and the amount added is 1.2 to 3.0 times the theoretical amount for iron removal.

8. The method for comprehensive recovery and utilization of germanium concentrate chloride distillation residue as described in claim 1, characterized in that, The neutralizing agent mentioned in step D is limestone, quicklime, or slaked lime.

9. The method for comprehensive recovery and utilization of germanium concentrate chloride distillation residue as described in claim 1, characterized in that, Step 1) involves directly evaporating and concentrating the iron-removed liquid f. The concentration ends when the mother liquor becomes turbid, at which point sulfation evaporation begins.

10. The method for comprehensive recovery and utilization of germanium concentrate chloride distillation residue as described in claim 1 or 9, characterized in that, The sulfation evaporation mentioned above involves adding zinc sulfate crystallization mother liquor or concentrated sulfuric acid for sulfation evaporation.

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