A method for recovering selenium and high value metals from arsenic-selenium alloy scrap

Abstract

The application discloses a method for efficiently recovering selenium and high-value metals from arsenic-selenium alloy waste, and belongs to the technical field of hydrometallurgy. The method comprises the following steps: 1) dissolving arsenic-selenium alloy waste by oxidizing acid leaching to obtain a leaching solution containing selenium, arsenic, antimony and germanium; 2) adjusting the reduction potential of selenium and arsenic by adjusting the pH of the solution to selectively reduce selenium and recover antimony by hydrolysis; 3) selectively adsorbing germanium by using tannin functionalized adsorption resin for the solution after hydrolysis; and 4) sulfidizing and precipitating arsenic from the solution after adsorption. The process realizes efficient separation of selenium and arsenic and recovery of high-value metals therein, the total recovery rate of selenium, antimony, germanium and arsenic is greater than 95%, the solution after reaction can be recycled, and good industrialization feasibility is achieved.

Description

Technical Field

[0001] This invention belongs to the field of hydrometallurgical technology, specifically relating to a method for recovering selenium and high-value metals from arsenic-selenium alloy waste, applicable to the efficient separation and high-value recovery of selenium, arsenic, germanium and antimony in arsenic-selenium alloy waste. Background Technology

[0002] Arsenic-selenium (As-Se) alloys, as important chalcogenide semiconductor materials, are widely used in glass optical fibers, mid-infrared lenses, and phase-change threshold switching devices due to their suitable photosensitivity and wide bandgap characteristics. To improve the performance of As-Se alloy-based optoelectronic devices, rare and dispersed metals such as germanium and antimony are often used as dopants. Therefore, the As-Se alloy waste generated during production, processing, and disposal becomes an important secondary resource for recovering selenium and rare and dispersed metals. The rational recycling of As-Se alloy waste has significant economic benefits and can reduce heavy metal pollution, thus possessing important environmental and industrial value.

[0003] Currently, methods for metal purification and separation mainly include solvent extraction, membrane separation, pyrometallurgy, and hydrometallurgy. Among these, pyrometallurgy is energy-intensive, causes severe equipment corrosion, and is prone to secondary pollution; solvent extraction and membrane separation are complex and costly, making them difficult to scale up; hydrometallurgy, with its mild reaction system, can significantly reduce equipment corrosion and has the advantages of low cost and easy control, making it the mainstream direction for metal waste recycling.

[0004] However, existing hydrometallurgical technologies for the recovery of arsenic-selenium alloy waste still have many shortcomings: First, arsenic and selenium have similar reduction potentials, and arsenic is easily reduced simultaneously during the reduction and recovery of selenium, leading to contamination of selenium products and low separation efficiency; second, the separation of high-value metals such as germanium and antimony is difficult, easily resulting in losses during the recovery process and low recovery rates; third, the process flow is incomplete, the mother liquor cannot be recycled, resource utilization is low, and arsenic treatment is incomplete, easily causing environmental hazards. Therefore, developing a green and sustainable recovery method that can achieve efficient separation and high recovery rate of selenium, arsenic, germanium, and antimony in arsenic-selenium alloy waste has become an urgent technical problem to be solved in this field. Summary of the Invention

[0005] In view of the problems of low recycling efficiency, incomplete element separation, low resource utilization, and easy secondary pollution in existing technologies for arsenic-selenium alloy waste, the purpose of this invention is to provide a method for efficiently recovering selenium and high-value metals from arsenic-selenium alloy waste, achieving efficient separation and high recovery rate of selenium, arsenic, germanium and antimony, while realizing the recycling of mother liquor, reducing production costs and reducing environmental pollution.

[0006] To achieve the above-mentioned objectives, the technical solution adopted by the present invention is as follows: A method for recovering selenium and high-value metals from arsenic-selenium alloy waste includes the following steps: Step 1: The arsenic-selenium alloy waste is crushed and sieved to obtain waste powder; Step 2: Add the waste powder obtained in Step 1 to an oxidizing solution containing sulfuric acid, and carry out a leaching reaction under heating and stirring to oxidize Se, As, Sb and Ge in the waste into ionic states and allow them to enter the liquid phase. After the reaction is completed, filter to obtain the leachate. Step 3: Add sulfuric acid with a final concentration of 0.5-3M to the leachate obtained in Step 2, and add a reducing agent dropwise under heating and stirring to carry out a reduction reaction, so that Se ions are reduced to elemental and precipitated. Filter to obtain elemental Se. After cooling the reaction solution, adjust the pH to induce Sb hydrolysis, and filter to obtain antimony oxide precipitate and hydrolyzed solution. Step 4: After hydrolysis in step 3, the liquid is pumped into an adsorption column filled with tannic acid functionalized adsorption resin for selective adsorption of Ge ions until the Ge concentration in the adsorption effluent reaches the breakthrough standard. Step 5: After adsorption saturation, the hydrochloric acid solution is pumped into the adsorption column for dynamic desorption, and the desorption solution containing Ge ions is collected. Step 6: Collect the effluent obtained in Step 4 and recover and separate the As component using sulfide precipitation technology. Add sulfuric acid to the solution after the As component is separated and recycle it for the leaching reaction process in Step 2.

[0007] Furthermore, the arsenic selenium alloy waste is derived from the waste generated during the arsenic selenium alloy processing, wherein the Se content is 55-65 wt%, the As content is 25-35 wt%, the Sb and Ge contents are both 1-5 wt%, and the remainder is other impurities; in step 1, the waste is crushed to ≤100 mesh using a ball mill or crusher.

[0008] Further, in step 2, the sulfuric acid-containing oxidizing solution is prepared by mixing sulfuric acid solution and hydrogen peroxide, wherein the final concentration of sulfuric acid is 0.5-3 mol / L; the solid-liquid mass-volume ratio of the waste to the sulfuric acid-containing oxidizing solution is controlled at 1g:10-40mL, and the total molar amount of all metals in the waste to the molar amount of hydrogen peroxide is 1:2.5~8.0; the leaching reaction temperature in step 2 is 60-95℃, and the leaching reaction time is 30-180 min.

[0009] Further, in step 3, the final concentration of sulfuric acid added to the leachate is 1.5-3M, and the reducing agent is hydrazine hydrate solution. To ensure that the selenium ions in the leachate are fully reduced to elemental selenium, the amount of hydrazine hydrate solution added needs to be excessive. For example, the actual amount of hydrazine hydrate solution added is 1.1 to 1.5 times the theoretical amount, where the theoretical amount is the theoretical molar amount of hydrazine hydrate solution required to completely reduce the Se ions in the leachate to elemental selenium.

[0010] Furthermore, in step 3, the temperature of the reduction reaction is 60-80 ℃, the time of the reduction reaction is 10-150 min, and after the reduction reaction is completed, the reduced reaction solution is obtained by hot filtration. The solid precipitate obtained by filtration is repeatedly washed with deionized water and 0.1-1M sodium hydroxide solution, and dried to obtain elemental Se product.

[0011] Furthermore, in step 3, the pH for inducing Sb hydrolysis is 0.5-4.

[0012] Furthermore, the tannic acid functionalized adsorption resin is a moderately polar adsorption resin with a polystyrene framework and possesses tannic acid functional groups. Its preparation method includes the following steps: S1: Chloromethylated styrene-divinylbenzene macroporous adsorption resin was used as a carrier and subjected to amination treatment. S2: The resin treated in step S1 is placed in an alkaline aqueous solution to fully swell, then filtered and washed with deionized water until neutral. Epichlorohydrin is added as a crosslinking activator, and the mixture is stirred at 30-50 ℃ for 1-3 h to introduce epoxy active groups onto the resin surface. S3: After the reaction in step S2 is completed, wash away excess epichlorohydrin; then, add tannic acid aqueous solution to the resin, adjust the pH of the system to 1.5-3.0, heat to 50-70 ℃ and reflux for 4-8 h, so that tannic acid is bonded to the resin skeleton through covalent ether bonds. S4: After the reaction in step S3 is completed, the solution is washed repeatedly with ethanol, deionized water and dilute sulfuric acid solution in sequence at room temperature until the washing solution has no obvious characteristic color of tannic acid. Then, it is treated with 3-5% hydrochloric acid at 30-50 ℃ for 1-3 h, and then treated with 3-5% NaOH solution at 30-50 ℃ for 1-3 h. After that, it is washed with deionized water until the effluent is neutral, and then fully soaked in 1-3M sulfuric acid solution for pretreatment. After washing with water until neutral, it is dried to obtain the tannic acid functionalized adsorption resin.

[0013] Further, in step S1, the amination treatment is carried out as follows: the resin is added to a dimethylamine aqueous solution with a mass concentration of 20-40% at a solid-liquid ratio of 1g:4-6mL, and the mixture is stirred and reacted at 50±5℃ for 4-8h. After filtration and washing, the treatment is completed.

[0014] Furthermore, in step S2, the alkaline aqueous solution is a sodium hydroxide solution with a concentration of 0.3-1.0 mol / L.

[0015] Furthermore, in step S2, the mass ratio of resin to epichlorohydrin is 1:1.5-3.0.

[0016] Furthermore, in step S3, the mass ratio of tannic acid to resin is 0.8-1.5:1, and the concentration of the tannic acid aqueous solution is 3-8 g / L.

[0017] Furthermore, in step S4, the mass concentration of the dilute sulfuric acid solution is 3-10%.

[0018] Furthermore, in step 4, the adsorption temperature is controlled at 20-50 ℃, and the breakthrough standard is that the concentration of Ge in the effluent is ≥1 mg / L.

[0019] Furthermore, in step 5, the concentration of the hydrochloric acid solution used for desorption is 6-10 mol / L, and elution is stopped when the Ge concentration in the desorption solution is ≤50 mg / L.

[0020] Furthermore, after desorption in step 5, the adsorption resin in the adsorption column is regenerated by water washing and acid washing in sequence to restore its adsorption capacity and recycle it for step 4. Acid washing regeneration is to acidify and transform the resin with 1-3M sulfuric acid to restore the adsorption activity of the resin functional groups.

[0021] Further, in step 6, the specific process of recovering and separating the As component from the adsorbed effluent using arsenic sulfide precipitation technology is as follows: sodium sulfide solution is added dropwise to the effluent, and the mixture is stirred and reacted at room temperature and pressure for 30-90 minutes, so that the arsenic ions in the effluent react with sodium sulfide to form a precipitate. The precipitate is collected by filtration, and the obtained precipitate solid is washed with deionized water and dried to obtain arsenic trisulfide. The filtrate is replenished with sulfuric acid and returned to the leaching reaction process in step 2.

[0022] Compared with the prior art, the present invention has the following advantages: 1. This invention employs an integrated process of oxidative acid leaching, selective reduction, resin adsorption, and stepwise precipitation, which can achieve comprehensive recovery of selenium, antimony, germanium, and arsenic. The recovery rate of each metal exceeds 95%, and the product has high purity, significantly improving the resource value and economic benefits of arsenic-selenium alloy waste.

[0023] 2. Based on potential-pH thermodynamic analysis, the optimal acidity was determined. Hydrazine hydrate was used as a selective reducing agent, which can efficiently reduce selenium without changing the valence state of arsenic, thus avoiding arsenic contamination of selenium products. The final purity of elemental selenium exceeded 99%, and the arsenic content was only 0.166%.

[0024] 3. Tannic acid-functionalized adsorption resin is selected to efficiently and selectively adsorb trace amounts of germanium. At the same time, the resin can be regenerated and recycled, realizing the enrichment of germanium and the reuse of resources.

[0025] 4. The process is green and sustainable. The reduction of hydrazine hydrate only produces nitrogen gas, with no secondary pollution. The mother liquor can be recycled for acid replenishment. Arsenic is treated with sulfide precipitation to avoid environmental pollution. The process is simple and easy to operate. The reaction conditions are mild and the energy consumption is low. No complicated equipment is required, making it suitable for large-scale industrial production. Attached Figure Description

[0026] Figure 1 The comparison results of the XRD pattern of crude selenium, the reduction product of Example 1 of the present invention, and the XRD pattern of the elemental selenium standard card are shown. Figure 2 This is a process flow diagram of the present invention. Detailed Implementation

[0027] The present invention will be further described in detail below with reference to specific embodiments, but the scope of protection of the present invention is not limited to the content described.

[0028] The adsorption resin used in this embodiment of the invention is a self-made tannic acid functionalized adsorption resin, and its detailed preparation steps are as follows: A. Polymerization: Styrene, divinylbenzene, and a porogen were mixed uniformly at a mass ratio of 10:2:12 to form the oil phase. The porogen was a mixture of toluene and n-heptane at a volume ratio of 1:2. Benzoyl peroxide was added to the oil phase as an initiator, with the initiator mass being 1% of the total mass of the monomers styrene and divinylbenzene. The oil phase was added to a dispersed aqueous phase containing 1 wt% polyvinyl alcohol, controlling the volume ratio of the oil phase to the aqueous phase to be 1:3. Suspension polymerization was carried out at a stirring speed of 300 rpm and a temperature of 85 ℃ for 10 hours. After the reaction, the product was filtered, washed with hot water, and vacuum dried to obtain macroporous styrene-divinylbenzene copolymer white spheres. The obtained styrene-divinylbenzene white spheres were thoroughly washed and activated successively with anhydrous ethanol, 5% (w / w) dilute sodium hydroxide solution, 3% (w / w) dilute sulfuric acid solution, and deionized water, and then vacuum dried for later use.

[0029] B. Chloromethylation and Amination: The white spheres were placed in a closed reactor equipped with a reflux condenser and a tail gas absorption device. Chloromethyl methyl ether was added, and the solid-liquid ratio of white spheres to chloromethyl methyl ether was controlled at 1 g: 6 mL. After swelling at room temperature for 2 hours, anhydrous ZnCl2 (35% by weight of white spheres) was added as a catalyst, and the mixture was heated to 55 °C and refluxed for 8 hours to introduce chloromethyl groups onto the resin backbone. After the reaction, the solid was filtered off and washed thoroughly with methanol and deionized water to obtain chloromethylated microspheres. Subsequently, the chloromethylated microspheres were added to a 30% dimethylamine aqueous solution at a solid-liquid ratio of 1 g: 5 mL and placed in a sealed pressure-resistant reactor. The reaction was carried out at 50 °C for 6 hours to convert chloromethyl groups into tertiary amine groups (-N(CH3)2). Finally, the mixture was washed with deionized water, 5% NaOH solution, and deionized water to obtain an amination macroporous resin intermediate.

[0030] C. Epoxy Activation and Tannic Acid Immobilization: The above-mentioned amination-modified macroporous resin intermediate was added to a 0.5 mol / L sodium hydroxide solution for complete swelling, filtered, and washed with deionized water until neutral. Subsequently, epichlorohydrin was added as a crosslinking activator at a resin-to-epoxyhydrin mass ratio of 1:2, and the mixture was stirred at 40 °C for 2 hours to introduce active epoxy alkyl sites on the resin surface. Then, an aqueous tannic acid solution with a resin-to-tannic acid mass ratio of 1:1.2 (tannic acid concentration 5 g / L) was added, and the pH of the system was adjusted to 2.0 ± 0.5 with dilute sulfuric acid. The mixture was then refluxed at 60 °C for 7 hours to allow the tannic acid to be stably bonded to the resin surface via covalent ether bonds.

[0031] D. Post-treatment and acidification pretreatment: The product is first washed repeatedly with ethanol, deionized water and 5% dilute sulfuric acid solution in sequence until the washing liquid has no obvious tannic acid characteristic color. After the initial washing, it is treated with 4% hydrochloric acid solution at 40 ℃ for 2 hours by stirring (the purpose of the 4% hydrochloric acid solution treatment is to remove the tannic acid physically adsorbed on the resin surface). Then it is treated with 4% sodium hydroxide solution at 40 ℃ for 2 hours by stirring to remove residual catalyst ZnCl2 and unreacted products to avoid long-term regeneration clogging of the resin. Then it is washed with deionized water until the effluent is neutral. Finally, it is pretreated by soaking in 2 mol / L sulfuric acid solution for 3 hours, washed with water until neutral, and then vacuum dried to obtain the acid-resistant tannic acid functionalized adsorption resin.

[0032] The self-made resin was determined to be based on polystyrene with tannic acid chelate groups bonded to its surface. The particle size ranged from 0.3 to 1.2 mm, and the specific surface area was ≥350 m². 2 / g, tannin loading ≥12%, static saturated adsorption capacity for germanium in 2 mol / L sulfuric acid system ≥18 mg / g.

[0033] Example 1: A method for efficiently recovering selenium and high-value metals from arsenic-selenium alloy waste, comprising the following steps (see...). Figure 2 ): 1) Pretreatment: Arsenic selenium alloy waste (containing 61.6 wt% Se, 32.1 wt% As, 2.8 wt% Ge, 2.1 wt% Sb and other impurities) is crushed and sieved to 100 mesh using a pulverizer.

[0034] 2) Oxidative acid leaching: Take 100 g of pretreated waste material, add 2000 mL of leaching agent (sulfuric acid concentration 2 mol / L, hydrogen peroxide concentration 2.54 mol / L), heat at 90 ℃ and leach for 120 min with continuous stirring at 300 rpm; after the reaction, filter to separate the leachate and leaching residue. The leaching rate of selenium is 95.8%, the leaching rate of arsenic is 95.1%, the leaching rates of germanium and antimony are both 100%, and the leaching residue rate is 6.5%.

[0035] 3) Selective reduction and hydrolysis separation of antimony: Take 1000 mL of the leachate obtained in step 2), and add concentrated sulfuric acid to adjust the sulfuric acid concentration in the leachate to 2 mol / L (because the water generated by the decomposition of hydrogen peroxide dilutes the acid solution, and the generation of arsenic acid and selenite consumes H₂). + (This leads to a decrease in the acidity of the system). The solution is heated to 80 °C and stirred at 300 rpm. Based on the Se concentration of 36 g / L in the leachate and approximately 75% of the Se in the solution being Se... 6+ The selenium was present in the form of 25% hydrazine hydrate (150 mL, 1.2 times the theoretical amount by mass), and the reaction was carried out for 30 min. After the reaction, the selenium reduction rate reached 99.9%. The product was filtered at 60 °C, and the solid precipitate was collected. It was washed three times with 0.5 mol / L sodium hydroxide solution, filtered, and dried at 100 °C for 2 h to obtain elemental selenium product with a selenium content of 99.2% and an arsenic content of 0.166%. The filtrate was cooled to room temperature and allowed to stand for 1 h. Then, the pH of the solution was adjusted from 0 to 0.7 to induce antimony hydrolysis and precipitation. The antimony oxide precipitate and the hydrolyzed solution were obtained by filtration. The antimony recovery rate was 96.7%.

[0036] The XRD pattern of the crude selenium reduction product obtained in Example 1 is shown in [reference]. Figure 1 .

[0037] 4) Resin Adsorption: An adsorption column (20 mm inner diameter, 200 mm height) was filled with 5 mL of tannic acid-functionalized adsorption resin (wet basis), and equilibrated sequentially with deionized water and 2 mol / L sulfuric acid solution. 450 mL of the hydrolyzed solution was pumped into the adsorption column using a peristaltic pump at a flow rate of 3 BV / h, and the adsorption temperature was 25 ℃. During dynamic adsorption, the germanium concentration in the effluent was monitored using ICP-OES. Adsorption was stopped when the Ge concentration in the effluent was ≥1 mg / L. Under these conditions, the average germanium concentration in the effluent was 0.045 mg / L, and the germanium adsorption rate was 99.2%.

[0038] 5) Desorption and preparation of germanium enrichment solution: An 8 mol / L hydrochloric acid solution was pumped into a saturated resin column at a flow rate of 3 BV / h using a peristaltic pump for dynamic desorption at 25 °C. The desorbed effluent was collected in segments according to bed volume (BV), with each BV effluent collected separately. The germanium concentration in each segment was determined using ICP-OES. After 8 BV of desorption, the total germanium content in the desorbate was 124.6 mg, with a desorption rate of 98.1%. The desorbate was evaporated and concentrated to 1 / 5 of its original volume to obtain a high-concentration germanium-enriched solution, which can be directly used to prepare high-purity germanium dioxide or metallic germanium products. ICP-MS analysis showed that the germanium purity in the enriched solution reached 99.9%, and the contents of impurities such as arsenic, antimony, and iron were all below 5 × 10⁻⁶. -4 The total germanium recovery rate was 95.6%.

[0039] 6) Resin Regeneration and Cycling Performance: After desorption, the resin column was first rinsed with deionized water until neutral. Then, 40 mL (8 BV) of 2 mol / L sulfuric acid solution was introduced for regeneration at a flow rate controlled at 3 BV / h to complete resin activation and regeneration. Experimental results showed that after 10 cycles of adsorption-desorption-regeneration, the germanium adsorption capacity of this tannic acid functionalized adsorption resin remained above 95% of its initial capacity, indicating stable resin structure and excellent regeneration performance.

[0040] 7) Arsenic sulfide precipitation recovery: Take the effluent obtained in step 4) and add it to a beaker. Stir magnetically at 20 °C at a stirring speed of 300 rpm. Slowly add 100 g / L sodium sulfide solution, the volume of which is 23% of the volume of the effluent. Continue stirring for 60 min. Filter and collect the precipitate, wash it three times with deionized water, and dry it at 100 °C for 2 h to obtain arsenic trisulfide precipitate. The arsenic recovery rate is 97.4%.

[0041] 8) Mother liquor recycling: Add 98% sulfuric acid to the filtered mother liquor obtained in step 7) to adjust the sulfuric acid concentration to 2 mol / L, and repeat the oxidation and acid leaching process in step 2.

[0042] 9) Stability verification: Experimental verification showed that after the mother liquor described in step 8) was repeatedly leached-reduced 3 times, the leaching rate of selenium remained above 90% and the reduction rate remained above 95%, indicating that the leaching-reduction effect was stable and there was no significant attenuation. During the cycle, the recovery efficiency of each element did not decrease significantly, further proving the industrial adaptability and resource recycling feasibility of the process.

[0043] Example 2: The experiment of Example 2 repeats steps 1)-2) of Example 1, except that in the oxidative acid leaching process of "step 2), the concentration of sulfuric acid in the leaching agent is adjusted to 0.5, 1, 1.5, 2.5 and 3 mol / L respectively", and the other conditions remain unchanged.

[0044] The effects of different sulfuric acid concentrations on the leaching rates of selenium, arsenic, germanium, and antimony during the oxidative acid leaching process in Examples 1-2 are summarized in Table 1.

[0045] Table 1. Effects of different sulfuric acid concentrations on the leaching rates of selenium, arsenic, germanium, and antimony. 0.5 63.1 75.2 97.8 91.5 1 81.7 87.0 100 100 1.5 85.7 90.1 100 100 2 95.8 95.1 100 100 2.5 96.6 95.7 100 100 3 97.5 97.9 100 100 .

[0046] As can be seen from Table 1, the leaching rate of each element increases with the increase of sulfuric acid concentration during the oxidative leaching process. When the sulfuric acid concentration exceeds 2 mol / L, the leaching rate of each element exceeds 90%.

[0047] Example 3: The experiment of Example 3 repeats steps 1) to 3) of Example 1. The only difference is that in the operation of "step 3), the sulfuric acid concentration in the leachate is adjusted to 0.5, 1, 1.5, 2.5 and 3 mol / L respectively", and the other conditions remain unchanged.

[0048] The effects of controlling different sulfuric acid concentrations on the reduction rates of selenium, arsenic, germanium, and antimony in step 3) of Examples 1 and 3 are summarized in Table 2.

[0049] Table 2 Effect of different sulfuric acid concentrations on the reduction rates (%) of selenium, arsenic, and germanium 0.5 88.7 0 0 1 95.3 0 0 1.5 98.9 0 0 2 99.9 0 0 2.5 99.9 0 0 3 99.9 0 0 .

[0050] As can be seen from Table 2, the reduction rate of selenium increases with the increase of sulfuric acid concentration. The reduction rate of selenium reaches a peak of 99.9% when the sulfuric acid concentration is 2 mol / L. Arsenic and germanium are not reduced when the sulfuric acid concentration is changed.

[0051] Example 4: The experiment of Example 4 repeats steps 1)-4) of Example 1. The only difference is that in "step 4), the flow rate of the hydrolyzed liquid through the adsorption column is adjusted to 1, 2, 4, 5 and 6 BV / h respectively", and the other conditions remain unchanged.

[0052] The effects of controlling different post-hydrolysis liquid flow rates on the germanium concentration and germanium adsorption rate in step 4) of Examples 1 and 4 are summarized in Table 3.

[0053] Table 3 Effect of flow rate on germanium concentration and germanium adsorption rate in effluent 1 0.021 99.68 2 0.030 99.54 3 0.045 99.20 4 0.057 98.92 5 0.086 98.38 6 0.125 97.62 .

[0054] As can be seen from Table 3, during the resin adsorption process, the concentration of germanium in the effluent also increases with the increase of the flow rate. The adsorption rate of germanium shows a decreasing trend but can still be maintained above 97%.

[0055] Example 5: The experiment of Example 5 repeats steps 1) to 4) of Example 1, except that in "step 4), the adsorption temperature is adjusted to 20, 30, 40, 50, 60 and 70 ℃ respectively", and the other conditions remain unchanged.

[0056] In step 4) of Example 5, the effects of controlling different adsorption temperatures on the germanium concentration and germanium adsorption rate of the effluent are summarized in Table 4.

[0057] Table 4. Effect of different adsorption temperatures on germanium concentration and germanium adsorption rate in the effluent. 20 0.053 99.00 30 0.039 99.30 40 0.062 98.81 50 0.095 98.15 60 0.138 97.36 70 0.186 96.42 .

[0058] As can be seen from Table 4, during the resin adsorption process, the concentration of germanium in the effluent first decreases and then increases with the increase of temperature, and the adsorption rate of germanium shows a trend of first increasing and then decreasing. This indicates that the resin is more suitable for adsorption under room temperature conditions. When the temperature rises to 70°C, the adsorption rate of germanium can still reach 96.42%.

[0059] The above embodiments demonstrate that the method of the present invention can achieve efficient separation and high recovery rate of selenium, arsenic, germanium and antimony in arsenic-selenium alloy waste. The process is stable and reliable and can be recycled.

[0060] Comparative Example 1: The oxidative acid leaching step uses hydrochloric acid leaching. 1) Pretreatment: Arsenic selenium alloy waste (containing 61.6 wt% Se, 32.1 wt% As, 2.8 wt% Ge, 2.1 wt% Sb and other impurities) is crushed and sieved to 100 mesh using a pulverizer.

[0061] 2) Oxidative acid leaching: Take 100 g of pretreated waste material, add 2000 mL of leaching agent (hydrochloric acid concentration 2 mol / L, hydrogen peroxide concentration 2.54 mol / L), heat at 90 ℃ and leach for 120 min with continuous stirring at 300 rpm; after the reaction, filter to separate the leachate and leaching residue. According to the test and calculation, the leaching rate of selenium is 59.7%, the leaching rate of arsenic is 60.3%, the leaching rates of germanium and antimony are both 99.8%, and the leaching residue rate is 28.6%.

[0062] 3) Selective reduction and hydrolysis separation of antimony: Take 1000 mL of the leachate obtained in step 2), adjust the hydrochloric acid concentration to 2 mol / L, heat to 80 ℃, and under stirring at 300 rpm, based on the Se concentration in the leachate being 24 g / L and approximately 75% of the Se in the solution being Se. 6+ Add 90 mL of 25% hydrazine hydrate (1.2 times the theoretical amount by mass) and react for 30 min. After the reaction, filter at 60 °C, collect the solid precipitate, wash repeatedly three times with 0.5 mol / L sodium hydroxide solution, filter again, and dry at 105 °C for 2 h to obtain elemental selenium product. Due to the low leaching rate, the yield of elemental selenium was significantly reduced, with an elemental selenium content of 99.0% and an arsenic content of 0.172%. Cool the filtrate to room temperature and let it stand for 1 h. Then adjust the pH of the solution from 0 to 0.7 to induce antimony hydrolysis precipitation. Filter again and dry at 100 °C for 2 h to obtain antimony oxide precipitate and hydrolyzed solution. The antimony recovery rate is 96.5%.

[0063] 4) Resin adsorption of germanium: Step 4) in Example 1 was repeated, using tannic acid-functionalized adsorption resin for dynamic adsorption. Due to changes in the acidity of the feed solution and interference from chloride ions, the germanium adsorption rate decreased to 94.3%, and the co-adsorption of impurities increased, affecting the subsequent purity.

[0064] 5) Desorption and regeneration: Repeat steps 5) and 6 in Example 1. The germanium desorption rate was 95.6%, but the impurity content in the product increased, and the total germanium recovery rate was only 90.1%.

[0065] 6) Arsenic sulfide precipitation recovery: Step 7 in Example 1 was repeated, and the arsenic recovery rate was 97.1%.

[0066] Comparison with Example 2: Using sulfur dioxide as a reducing agent 1) Oxidative acid leaching: Repeat steps 1) and 2) in Example 1 to obtain the leachate. The leaching rate of selenium was calculated to be 95.7%, the leaching rate of arsenic was 95.0%, and the leaching rates of germanium and antimony were both 100%.

[0067] 2) Selective Reduction: Take 1000 mL of the leachate obtained in step 1), replace the reducing agent with SO2 gas, and maintain the basic conditions of the leachate as in the reduction process of Example 1. Continuously introduce SO2 at a rate of 0.3 L / min. The total gas flow rate is based on a Se concentration of 46 g / L in the solution and 75% of the Se in the solution being Se2. 6+The amount of SO2 introduced was 1.5 times the theoretical reduction amount (20 L), with a total aeration time of 100 min and an SO2 injection rate of 30 L. Other operating procedures, including temperature, stirring, and hot filtration, remained unchanged. During the reaction, the solution initially became turbid but gradually clarified. After the reaction, the solution was filtered at 60 °C, and the solid precipitate was collected. This precipitate was washed three times with 0.5 mol / L sodium hydroxide solution, filtered again, and dried at 100 °C for 2 h to obtain elemental selenium. Analysis showed a selenium reduction rate of only 68%, an elemental selenium content of 98.8%, and an arsenic content of 0.685%. The filtrate was cooled to 25 °C, and the pH was adjusted from 0 to 0.7 to induce antimony hydrolysis and precipitation. The resulting antimony oxide precipitate and hydrolyzed solution were obtained through filtration, with an antimony recovery rate of 96.2%.

[0068] 3) Resin adsorption of germanium: Step 4 in Example 1 was repeated, using tannic acid-functionalized adsorption resin for dynamic adsorption, with a germanium adsorption rate of 99.1%. However, due to incomplete selenium separation in the reduction step and a complex solution system, the purity of the subsequent germanium product decreased.

[0069] 4) Desorption and regeneration: Steps 5) and 6 in Example 1 were repeated. The germanium desorption rate was 98.0%, but the total recovery rate dropped to 91.3%.

[0070] 5) Arsenic sulfide precipitation: Repeat step 7 in Example 1), arsenic recovery rate 97.3%.

Claims

1. A method for recovering selenium and high-value metals from arsenic-selenium alloy waste, characterized in that, Includes the following steps: Step 1: The arsenic-selenium alloy waste is crushed and sieved to obtain waste powder; Step 2: Add the waste powder obtained in Step 1 to an oxidizing solution containing sulfuric acid, and carry out a leaching reaction under heating and stirring to oxidize Se, As, Sb and Ge in the waste into ionic states and allow them to enter the liquid phase. After the reaction is completed, filter to obtain the leachate. Step 3: Add sulfuric acid with a final concentration of 0.5-3M to the leachate obtained in Step 2, and add a reducing agent dropwise under heating and stirring to carry out a reduction reaction, so that Se ions are reduced to elemental and precipitated. Filter to obtain elemental Se. After cooling the reaction solution, adjust the pH to induce Sb hydrolysis, and filter to obtain antimony oxide precipitate and hydrolyzed solution. Step 4: After hydrolysis in step 3, the liquid is pumped into an adsorption column filled with tannic acid functionalized adsorption resin for selective adsorption of Ge ions until the Ge concentration in the adsorption effluent reaches the breakthrough standard. Step 5: After adsorption saturation, the hydrochloric acid solution is pumped into the adsorption column for dynamic desorption, and the desorption solution containing Ge ions is collected. Step 6: Collect the effluent obtained in Step 4 and recover and separate the As component by sulfide precipitation technology. Add sulfuric acid to the solution after the As component is separated and recycle it for the leaching reaction process in Step 2. In step 2, the sulfuric acid-containing oxidizing solution is prepared by mixing sulfuric acid solution and hydrogen peroxide; In step 3, the reducing agent is hydrazine hydrate solution.

2. The method for recovering selenium and high-value metals from arsenic-selenium alloy waste as described in claim 1, characterized in that, The arsenic selenium alloy waste is derived from the waste generated during the arsenic selenium alloy processing. The waste contains 55-65 wt% Se, 25-35 wt% As, 1-5 wt% Sb and Ge, and the remainder consists of other impurities. In step 1, the waste is crushed to ≤100 mesh using a ball mill or crusher.

3. The method for recovering selenium and high-value metals from arsenic-selenium alloy waste as described in claim 1, characterized in that, In step 2, the final concentration of sulfuric acid in the oxidation solution is 0.5-3 mol / L; the solid-liquid mass-volume ratio of the waste to the sulfuric acid-containing oxidation solution is controlled at 1g:10-40mL, and the total molar amount of all metals in the waste to the molar amount of hydrogen peroxide is 1:2.5~8.0; the leaching reaction temperature in step 2 is 60-95℃, and the leaching reaction time is 30-180 min.

4. The method for recovering selenium and high-value metals from arsenic-selenium alloy waste as described in claim 1, characterized in that, In step 3, the final concentration of sulfuric acid added to the leachate is 1.5-3M, and the actual amount of hydrazine hydrate solution added is 1.1 to 1.5 times the theoretical amount. The theoretical amount is the theoretical molar amount of hydrazine hydrate solution that can completely reduce the Se ions in the leachate to elemental form. In step 3, the temperature of the reduction reaction is 60-80 ℃, and the time of the reduction reaction is 10-150 min. After the reduction reaction is completed, the reaction solution is obtained by hot filtration. The solid precipitate obtained by filtration is repeatedly washed with deionized water and 0.1-1M sodium hydroxide solution, and then dried to obtain elemental Se product.

5. The method for recovering selenium and high-value metals from arsenic-selenium alloy waste as described in claim 1, characterized in that, In step 3, the pH for inducing Sb hydrolysis is 0.5-4.

6. The method for recovering selenium and high-value metals from arsenic-selenium alloy waste as described in claim 1, characterized in that, The tannic acid functionalized adsorption resin is a moderately polar adsorption resin with a polystyrene framework and tannic acid functional groups. Its preparation method is as follows: Includes the following steps: S1: Chloromethylated styrene-divinylbenzene macroporous adsorption resin was used as a carrier and subjected to amination treatment. S2: The resin treated in step S1 is placed in an alkaline aqueous solution to fully swell, then filtered and washed with deionized water until neutral. Epichlorohydrin is added as a crosslinking activator, and the mixture is stirred at 30-50 ℃ for 1-3 h to introduce epoxy active groups onto the resin surface. S3: After the reaction in step S2 is completed, wash away excess epichlorohydrin; then, add tannic acid aqueous solution to the resin, adjust the pH of the system to 1.5-3.0, heat to 50-70 ℃ and reflux for 4-8 h, so that tannic acid is bonded to the resin skeleton through covalent ether bonds. S4: After the reaction in step S3 is completed, the solution is washed repeatedly with ethanol, deionized water and dilute sulfuric acid solution in sequence at room temperature until the washing solution has no obvious characteristic color of tannic acid. Then, it is treated with 3-5% hydrochloric acid at 30-50 ℃ for 1-3 h, and then treated with 3-5% NaOH solution at 30-50 ℃ for 1-3 h. After that, it is washed with deionized water until the effluent is neutral, and then fully soaked in 1-3M sulfuric acid solution for pretreatment. After washing with water until neutral, it is dried to obtain the tannic acid functionalized adsorption resin.

7. The method for recovering selenium and high-value metals from arsenic-selenium alloy waste as described in claim 6, characterized in that, In step S1, the amination treatment is carried out as follows: the resin is added to a dimethylamine aqueous solution with a mass concentration of 20-40% at a solid-liquid ratio of 1g:4-6mL, and the mixture is stirred and reacted at 50±5℃ for 4-8h. After filtration and washing, the treatment is completed.

8. The method for recovering selenium and high-value metals from arsenic-selenium alloy waste as described in claim 6, characterized in that, In step S2, the alkaline aqueous solution is a sodium hydroxide solution with a concentration of 0.3-1.0 mol / L; In step S2, the mass ratio of resin to epichlorohydrin is 1:1.5-3.0; In step S3, the concentration of the tannic acid aqueous solution is 3-8 g / L; In step S3, the mass ratio of tannic acid to resin is 0.8-1.5:1; In step S4, the mass concentration of the dilute sulfuric acid solution is 3-10%.

9. The method for recovering selenium and high-value metals from arsenic-selenium alloy waste as described in claim 1, characterized in that, In step 4, the adsorption temperature is controlled at 20-50 ℃, and the breakthrough standard is that the Ge concentration in the effluent is ≥1 mg / L; In step 6, the specific process of recovering and separating the As component from the adsorbed effluent using arsenic sulfide precipitation technology is as follows: sodium sulfide solution is added dropwise to the effluent, and the mixture is stirred and reacted at room temperature and pressure for 30-90 minutes to allow the arsenic ions in the effluent to react with sodium sulfide to form a precipitate. The precipitate is collected by filtration, and the obtained precipitate solid is washed with deionized water and dried to obtain arsenic trisulfide. The filtrate is replenished with sulfuric acid and returned to the leaching reaction process in step 2.

10. The method for recovering selenium and high-value metals from arsenic-selenium alloy waste as described in claim 1, characterized in that, In step 5, the concentration of the hydrochloric acid solution used for desorption is 6-10 mol / L, and elution is stopped when the Ge concentration in the desorption solution is ≤50 mg / L; After desorption in step 5, the adsorption resin in the adsorption column is regenerated by water washing and acid washing in sequence to restore its adsorption capacity and recycle it for step 4. Acid washing regeneration is to acidify and transform the resin with 1-3M sulfuric acid to restore the adsorption activity of the resin functional groups.

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