Method for stepwise selectively leaching zinc, germanium, indium and tin from zinc smelting waste residues

Abstract

The invention relates to the technical field of solid waste recycling, and discloses a method for stepwise selectively leaching zinc, germanium, indium and tin from zinc smelting waste residues, which comprises the following steps: mixing hydrogen peroxide and a sulfuric acid solution, adding the zinc smelting waste residues, and carrying out potential-controlled neutral leaching under the action of ultrasonic waves to obtain first leaching residues and first leaching liquid; mixing the first leaching residues with hydrochloric acid and tartaric acid, and performing coordination leaching to obtain second leaching residues and second filtrate; according to the method, first-stage leaching is carried out through cooperation of ultrasonic waves and hydrogen peroxide enhanced oxidation, sulfide such as zinc sulfide is effectively promoted to be converted into oxide, zinc is preferentially dissolved out, and meanwhile dissolution of germanium, indium and tin is inhibited, so that the germanium, the indium and the tin are enriched in leaching residues. In the second-stage leaching, hydrochloric acid effectively destroys a lead sulfate wrapping layer formed in the neutral leaching process, and wrapped valuable metal is released; tartaric acid forms a stable soluble complex with germanium, indium and tin ions, and efficient selective leaching is achieved.

Description

Technical Field

[0001] This invention relates to the field of solid waste recycling technology, and more specifically, to a method for selectively leaching zinc, germanium, indium, and tin from zinc smelting slag in stages. Background Technology

[0002] Zinc, germanium, indium, and tin, as key strategic metals, play an irreplaceable role in fields such as electronics, new energy, and high-end manufacturing. While global zinc resources are relatively abundant, the scarcity of germanium (crustal abundance 1-7 ppm), indium (primary ore grade <100 ppm), and tin (recoverable reserves declining annually) is becoming increasingly prominent. According to the U.S. Geological Survey (USGS), global annual germanium production is less than 200 tons, and annual indium production is only 800 tons, with approximately 30% of germanium and 50% of indium relying on secondary resource recovery. Zinc oxide dust, a major byproduct of zinc smelting, is rich in zinc (15-55%), germanium (0.01-0.2%), indium (0.005-0.08%), and tin (0.1-6%), and has become an important urban mining resource. However, traditional dust treatment processes generally suffer from low metal recovery rates, lengthy processes, and high acid and alkali consumption. Furthermore, heavy metals such as lead and silver are easily lost with the waste residue, resulting in resource waste and environmental pollution. Therefore, developing efficient and green multi-metal synergistic recycling technologies has become an important issue in the metallurgical field.

[0003] Currently, the hydrometallurgical process for zinc oxide dust is based on two- or three-stage sulfuric acid leaching, using atmospheric pressure or oxygen pressure processes to leach zinc, germanium, and indium. However, it still faces the following key bottlenecks: (1) Poor selectivity. Strong acid leaching causes zinc, germanium, indium, and tin to dissolve simultaneously (e.g., zinc leaching rate >95% and germanium leaching rate >80% in sulfuric acid leaching). Subsequent separation requires multi-stage extraction or precipitation, which is complex and costly. (2) Complexation interference. That is, germanium and indium are prone to forming colloids or complexes in acidic media (e.g., GeO2·nH2O, In(OH)3), which inhibits leaching efficiency. Reducing agents (e.g., SO2) need to be added, which exacerbates environmental risks. (3) Loss of valuable metals. That is, some zinc, germanium, and indium in zinc oxide dust exist in the form of sulfides. Additional oxidants (e.g., manganese powder) need to be added to promote the dissolution of sulfides, which increases the impurity content in the solution and constitutes a risk of heavy metal leakage. (4) Tin is difficult to dissolve. Tin compounds in zinc oxide fumes cannot be directly dissolved in traditional sulfuric acid leaching processes. They often need to be further recovered through pyrometallurgical processes during lead smelting, resulting in resource waste and additional consumption.

[0004] In recent years, the application of green organic complexing agents has provided new ideas for multi-metal leaching. For example, organic acids such as tartaric acid, citric acid, and oxalic acid, due to their environmental friendliness and strong complexing ability, can selectively extract germanium (forming Ge(C4H4O6)3). 2- Indium (In(C4H4O6)) +However, the application of the above system in zinc oxide flue dust still has the following problems: (1) Organic matter interferes with the main zinc smelting process. Although organic acids can form soluble complexes with germanium and indium, the high concentration of organic matter in the solution not only affects the impurity removal efficiency, but also significantly reduces the cell voltage and current efficiency in the zinc electrowinning process, and directly affects the quality of zinc sheets. (2) Insufficient process adaptability: Existing studies mostly focus on single metal recovery and lack systematic exploration of multi-component synergistic leaching and enrichment of zinc-germanium-indium-tin-lead-silver, which restricts the industrial application of the technology. Existing studies mostly focus on single metal recovery and lack systematic exploration of multi-component synergistic leaching and enrichment of zinc-germanium-indium-tin-lead-silver, which restricts the industrial application of the technology. Summary of the Invention

[0005] In view of this, the present invention proposes a method for selectively leaching zinc, germanium, indium, and tin from zinc smelting waste slag in stages, aiming to solve the problem of the lack of a systematic method for leaching and enriching zinc, germanium, indium, tin, lead, silver, and other metals in zinc smelting waste slag in the current technology.

[0006] This invention proposes a method for selectively leaching zinc, germanium, indium, and tin from zinc smelting waste in stages, comprising the following steps: 1) After mixing hydrogen peroxide and sulfuric acid solution, add zinc smelting waste residue and perform controlled potential neutral leaching under ultrasonic action to obtain the first leaching residue and the first leaching solution. 2) The first leaching residue obtained in step 1) is mixed with hydrochloric acid and tartaric acid for complexation leaching to obtain the second leaching residue and the second filtrate; The first leachate contains zinc sulfate; The second leachate contains germanium ions, indium ions, and tin ions; The second leaching residue contains lead and silver; The zinc smelting waste residue is zinc oxide dust.

[0007] Preferably, the concentration of the sulfuric acid solution in step 1) is 100~160 g / L; The solid-liquid ratio of the sulfuric acid solution to the zinc smelting waste residue is 2.5~6.5 mL / g; The solid-liquid ratio of the hydrogen peroxide to the zinc smelting waste residue is 0.017~0.17mL / g.

[0008] Preferably, the power of the ultrasonic wave in step 1) is 120~600W; The initial redox potential for controlled-potential neutral leaching is 630~695mV, and the leaching time is 30~180min.

[0009] Preferably, in step 1), hydrogen peroxide is continuously supplied to the system from the start of leaching until 20 minutes before the end of leaching during the controlled potential neutral leaching process. The total amount of hydrogen peroxide delivered is 0.17~1.17 mL / g, which is the solid-liquid ratio of zinc smelting waste.

[0010] Preferably, the concentration of hydrochloric acid in step 2) is 0.5~4 mol / L; The solid-liquid ratio of the hydrochloric acid to the first leaching residue is 4 mL / g; The mass ratio of tartaric acid to initial zinc smelting waste is 0.17~0.83.

[0011] Preferably, the temperature for coordination leaching in step 2) is 50~90℃, and the time for coordination leaching is 20~120min.

[0012] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention provides a method for selectively leaching germanium, indium, and tin from zinc smelting secondary resources. This process achieves efficient separation and recovery of zinc from germanium, indium, and tin, and has advantages such as short process, low cost, simple operation, and environmental friendliness. In the first stage of the leaching process, ultrasonic waves are used in conjunction with hydrogen peroxide to enhance the oxidative leaching process, effectively promoting the conversion of sulfides such as zinc sulfide into oxides and preferentially dissolving zinc, while inhibiting the dissolution of germanium, indium, and tin, causing them to accumulate in the leaching residue. The ultrasonic cavitation effect not only significantly enhances mass transfer and destroys the surface passivation layer, but also promotes the generation of active free radicals such as superoxide, hydroxyl, and singlet oxygen, improving the reaction rate and selectivity. Subsequently, in the hydrochloric acid-tartaric acid system, hydrochloric acid effectively destroys the lead sulfate coating layer formed during the neutral leaching process, releasing the encapsulated valuable metals; tartaric acid forms stable and soluble complexes with germanium, indium, and tin ions, achieving efficient and selective leaching. Ultimately, zinc can be directly returned to the main electrolysis process, while germanium, indium, and tin enter the solution for further separation and recovery. Lead and silver are enriched in the final residue. No toxic gases are generated, and the entire process is clean and efficient, achieving the cascade separation and comprehensive resource utilization of valuable metals. In the controlled-potential neutral leaching process, the leaching rates of zinc, germanium, indium, and tin can reach 73.11%, 1.55%, 0.21%, and 0.00034%, respectively. In the coordination leaching process, the leaching rates of germanium, indium, and tin can reach 97.53%, 96.19%, and 87.2%, respectively. Attached Figure Description

[0013] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings: Figure 1 This is a process flow diagram of the selective leaching of zinc, germanium, indium, and tin from zinc smelting waste slag according to the present invention. Figure 2 The image shown is the XRD pattern of the zinc smelting waste used in Example 1 of this invention. Figure 3 The images show the XRD patterns of the leaching residues obtained in Example 1 and Comparative Example 2. Figure 3 In this context, FSL represents the first leaching residue in Example 1. Figure 3 In this context, SSL represents the second leaching residue in Example 1. Figure 3 In this context, SSLWHA represents the leaching residue from the second stage of Comparative Example 2, where only tartaric acid was added. Figure 4 This is a graph showing the free radical intensity of different systems during the first leaching stage in Embodiment 1 of the present invention; Figure 5 The diagram shows the coordination structure and adsorption energy of tartaric acid, zinc oxide, germanium oxide, indium oxide, tin oxide, and lead sulfate during the second leaching stage in Example 1 of this invention. Detailed Implementation

[0014] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention. It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the present invention.

[0015] Furthermore, regarding the numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included within this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0016] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0017] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0018] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0019] This invention provides a method for selectively leaching zinc, germanium, indium, and tin from zinc smelting waste in stages, comprising the following steps: 1) After mixing hydrogen peroxide and sulfuric acid solution, add zinc smelting waste residue and perform controlled potential neutral leaching under ultrasonic action to obtain the first leaching residue and the first leaching solution. 2) The first leaching residue obtained in step 1) is mixed with hydrochloric acid and tartaric acid for complexation leaching to obtain the second leaching residue and the second filtrate; The first leachate contains zinc sulfate; The second leachate contains germanium ions, indium ions, and tin ions; The second leaching residue contains lead and silver; The zinc smelting waste residue is zinc oxide dust.

[0020] Step 1) involves the following chemical reactions:

[0021] Step 2) involves the following chemical reactions:

[0022] In this invention, the concentration of the sulfuric acid solution in step 1) is 100~160g / L, preferably 110~150g / L, more preferably 120~140g / L, and even more preferably 130g / L.

[0023] In this invention, the solid-liquid ratio of the sulfuric acid solution to the zinc smelting waste residue is 2.5~6.5 mL / g, preferably 3~6 mL / g, more preferably 3.5~5.5 mL / g, and even more preferably 4~5 mL / g.

[0024] In this invention, the solid-liquid ratio of hydrogen peroxide to zinc smelting waste is 0.017~0.17 mL / g, preferably 0.02~0.15 mL / g, more preferably 0.05~0.12 mL / g, and even more preferably 0.08~0.1 mL / g.

[0025] In this invention, the power of the ultrasonic wave in step 1) is 120~600W, preferably 150~550W, more preferably 200~400W, and even more preferably 250~350W.

[0026] In this invention, the initial redox potential of the controlled potential neutral leaching is 630~695mV; the leaching time is 30~180min, preferably 60~150min, more preferably 80~120min, and even more preferably 90~100min.

[0027] In this invention, during the controlled potential neutral leaching process described in step 1), hydrogen peroxide is continuously supplied to the system from the start of leaching until 20 minutes before the end of leaching. The total amount of hydrogen peroxide transported and the solid-liquid ratio of zinc smelting waste slag are 0.17~1.17 mL / g, preferably 0.2~1.1 mL / g, more preferably 0.4~0.9 mL / g, and even more preferably 0.6~0.8 mL / g.

[0028] In this invention, the concentration of hydrochloric acid in step 2) is 0.5~4 mol / L, preferably 0.5~3.5 mol / L, more preferably 1~3 mol / L, and even more preferably 1.5~2.5 mol / L.

[0029] The solid-liquid ratio of the hydrochloric acid to the first leaching residue is 4 mL / g.

[0030] The mass ratio of tartaric acid to initial zinc smelting waste is 0.17~0.83, preferably 0.2~0.8, more preferably 0.3~0.6, and even more preferably 0.4~0.5.

[0031] In this invention, the temperature of coordination leaching in step 2) is 50~90℃, preferably 55~85℃, more preferably 60~80℃, and even more preferably 65~75℃; the time of coordination leaching is 20~120min, preferably 40~100min, more preferably 60~80min, and even more preferably 70min.

[0032] Example 1 (1) Take 30g of zinc smelting waste residue (zinc oxide dust) and dry it for later use; set the temperature of the constant temperature magnetic stirring equipment to room temperature and the speed to 100rpm, add 150mL of sulfuric acid solution with a concentration of 100g / L and 2mL of hydrogen peroxide, control the potential to above 630mV, add zinc oxide dust after stirring evenly, set the ultrasonic power to 450W, and carry out controlled potential neutral leaching. In the first 30min after the start of leaching, use a peristaltic pump to continuously input 5.1mL of hydrogen peroxide into the equipment. After the hydrogen peroxide is delivered, continue leaching for 20min.

[0033] After leaching, the mixed system is filtered and separated to obtain a first leaching solution containing zinc sulfate and a first leaching residue. The first leaching residue is washed twice with water, and the washing liquid is combined with the first leaching solution.

[0034] (2) The washed first leaching residue was placed back into a constant temperature magnetic stirrer, and a hydrochloric acid solution with a mass-to-volume ratio of 4 mL:1 g and a concentration of 3 mol / L was added, along with tartaric acid solid with a mass-to-volume ratio of 0.33:1. Coordination leaching was carried out at 90℃ and 100 rpm. Leaching was completed after 90 min. The mixture was filtered to obtain a second leaching solution containing germanium, indium, and tin, and a second leaching residue containing lead and silver. The second leaching residue was dried in a vacuum drying oven at 60℃ for 12 h.

[0035] The leaching rates of zinc, germanium, indium and tin during the controlled potential neutral leaching process in step (1) were 73.11%, 1.55%, 0.21% and 0.00034%, respectively.

[0036] In the coordination leaching process described in step (2), the leaching rates of germanium, indium, and tin are 97.53%, 96.19%, and 87.2%, respectively.

[0037] The zinc, germanium, indium, and tin contents in the second leaching residue were 12.65%, 0.0158%, 0.0121%, and 2.59%, respectively.

[0038] Phase analysis of the zinc smelting waste used in this embodiment was performed using Cu-Kα as the X-ray source and an X-ray diffractometer with λ=0.15416nm. The results are as follows: Figure 2 As shown in Table 1, its elemental composition is as follows.

[0039] Table 1. Elemental composition of zinc smelting waste residue

[0040] Using Cu-Kα as the X-ray source, an X-ray diffractometer (XRD) with λ=0.15416nm was used to perform phase analysis on the first leaching residue obtained in step (1) of this embodiment, the second leaching residue obtained in step (2), and the second leaching residue obtained in step (2) of Comparative Example 2. The results are as follows: Figure 3 As shown, Figure 3 In this context, FSL represents the first leaching residue in Example 1. Figure 3 In this context, SSL represents the second leaching residue in Example 1. Figure 3 In Table 2, SSLWHA represents the leaching residue from the second stage of Comparative Example 2 with only tartaric acid added. The elemental composition of the first and second leaching residues is shown in Table 2.

[0041] Table 2. Elemental composition of the first and second leaching residues

[0042] Figure 4The graph shows the free radical intensity of different systems during the first leaching stage in Example 1 of this invention. It can be seen from the graph that under the sulfuric acid (H) system, the three transient free radicals are almost non-existent. After the addition of hydrogen peroxide (HH), the intensity of the three free radicals increases significantly. The introduced ultrasonic waves (UHH) can accelerate the decomposition of hydrogen peroxide, thereby generating more oxidizing free radicals. This is very beneficial for the controlled potential leaching to promote the transformation of sulfides and open the zinc circuit.

[0043] Figure 5 The diagrams show the coordination structures and adsorption energies of tartaric acid with zinc oxide, germanium oxide, indium oxide, tin oxide, and lead sulfate during the second leaching stage in Example 1 of this invention. The results indicate that all calculated adsorption energies are negative, meaning the adsorption process is spontaneous. Among them, C4H6O6 exhibits the lowest adsorption energy on the GeO2 surface (Eads = 4.20 eV), showing the strongest binding effect, which is highly consistent with the significant increase in Ge leaching rate observed in subsequent experiments. Based on the adsorption energy, the adsorption order of C4H6O6 on the surfaces of various metal compounds is inferred to be: GeO2 > ZnO > In2O3 > SnO2 > PbSO4. This order highly matches the selective leaching efficiency of Zn, Ge, In, and Sn, as well as the poor solubility of Pb in the experiments, indicating that adsorption energy is one of the key thermodynamic parameters controlling leaching selectivity.

[0044] Example 2 (1) Take 30g of dried zinc oxide dust (elemental composition as in Table 1), set the temperature of the constant temperature magnetic stirrer to room temperature and the speed to 100rpm, add 120mL of sulfuric acid solution with a concentration of 130g / L (solid-liquid ratio of sulfuric acid to waste residue 4mL / g) and 1mL of hydrogen peroxide (initial hydrogen peroxide solid-liquid ratio 0.033mL / g), control the potential to be above 630mV, stir evenly and then add the waste residue. Set the ultrasonic power to 360W (power density 3W / mL) and start the controlled potential neutral leaching; after the leaching starts, continuously input 6mL of hydrogen peroxide through a peristaltic pump for the first 40min, and continue leaching for 20min after the delivery is completed (total leaching time 60min).

[0045] After leaching, the solution is filtered, the first leachate is collected for testing, and the first leachate residue is washed twice with deionized water. The washing liquid is then combined with the first leachate.

[0046] (2) The washed first leaching residue was transferred to a stirring device, and 2 mol / L hydrochloric acid solution with a solid-liquid ratio of 4 mL / g and 15 g tartaric acid (tartaric acid to initial waste residue mass ratio of 0.5) were added. Coordination leaching was carried out at 75℃ and 100 rpm for 70 min. After leaching, the residue was filtered, and the second leaching solution was tested. The second leaching residue was vacuum dried at 60℃ for 12 h.

[0047] Test results: Step (1) Neutral leaching: Zinc leaching rate 76.23%, Germanium leaching rate 1.81%, Indium leaching rate 0.25%, Tin leaching rate 0.00042%; Step (2) Coordination leaching: Germanium leaching rate 98.12%, indium leaching rate 97.05%, tin leaching rate 88.5%; Elemental composition of the second leaching residue (wt%): Zn 10.32, Pb 51.27, Sn 2.15, Ge 0.0125, In 0.0098, Ag 0.0721.

[0048] Example 3 (1) Take 30g of dried zinc oxide dust, set the stirring equipment temperature to room temperature and the speed to 100rpm, add 195mL of sulfuric acid solution with a concentration of 160g / L (solid-liquid ratio 6.5mL / g) and 5.1mL of hydrogen peroxide (initial solid-liquid ratio 0.17mL / g), control the potential above 630mV, stir evenly and then add the slag. Set the ultrasonic power to 780W (power density 4W / mL) and start leaching; after the start of leaching, continuously input 30mL of hydrogen peroxide for the first 60min (total amount 35.1mL, solid-liquid ratio 1.17mL / g), and continue leaching for 20min after the input is completed (total leaching time 80min).

[0049] The first leachate and the first leachate residue were separated by filtration. The residue was washed twice and then used for later use.

[0050] (2) Add 4 mol / L hydrochloric acid solution (solid-liquid ratio 4 mL / g) and 24.9 g tartaric acid (mass ratio 0.83) to the first leaching residue, and perform complexation leaching at 90℃ and 100 rpm for 120 min. After filtration, the second leaching residue is dried for testing.

[0051] Test results: Step (1) Neutral leaching: Zinc leaching rate 78.56%, Germanium leaching rate 2.03%, Indium leaching rate 0.28%, Tin leaching rate 0.00051%; Step (2) Coordination leaching: Germanium leaching rate 98.75%, indium leaching rate 97.83%, tin leaching rate 90.1%; Elemental composition of the second leaching residue (wt%): Zn 8.95, Pb 53.16, Sn 1.82, Ge 0.0097, In 0.0076, Ag 0.0754.

[0052] Example 4 (1) Take 30g of dried zinc oxide dust, set the stirring equipment temperature to room temperature and the speed to 100rpm, add 75mL of sulfuric acid solution with a concentration of 110g / L (solid-liquid ratio 2.5mL / g) and 0.51mL of hydrogen peroxide (initial solid-liquid ratio 0.017mL / g), control the potential above 630mV, stir evenly and then add the slag. Set the ultrasonic power to 150W (power density 2W / mL) and start leaching; after the start of leaching, continuously input 4.59mL of hydrogen peroxide for the first 20min (total 5.1mL, solid-liquid ratio 0.17mL / g), and continue leaching for 10min after the input is completed (total leaching time 30min).

[0053] The first leaching residue is filtered, separated, and washed.

[0054] (2) Add 0.5 mol / L hydrochloric acid solution (solid-liquid ratio 4 mL / g) and 3 g tartaric acid (mass ratio 0.1) to the first leaching residue, and perform complexation leaching at 50℃ and 100 rpm for 20 min. Filter and treat the residue.

[0055] Test results: Step (1) Neutral leaching: Zinc leaching rate 68.32%, Germanium leaching rate 1.21%, Indium leaching rate 0.18%, Tin leaching rate 0.00029%; Step (2) Coordination leaching: Germanium leaching rate 90.57%, indium leaching rate 88.32%, tin leaching rate 75.8%; Elemental composition of the second leaching residue (wt%): Zn 15.78, Pb 47.35, Sn 3.26, Ge 0.0213, In 0.0185, Ag 0.0652.

[0056] Example 5 (1) Take 30g of dried zinc oxide dust, set the stirring equipment temperature to room temperature and the speed to 100rpm, add 165mL of sulfuric acid solution with a concentration of 140g / L (solid-liquid ratio 5.5mL / g) and 3mL of hydrogen peroxide (initial solid-liquid ratio 0.1mL / g), control the potential above 630mV, stir evenly and then add the slag. Set the ultrasonic power to 495W (power density 3W / mL) and start leaching; after the start of leaching, continuously input 15mL of hydrogen peroxide for the first 50min (total 18mL, solid-liquid ratio 0.6mL / g), and continue leaching for 30min after the input is completed (total leaching time 80min).

[0057] The first leaching residue is filtered, separated, and washed.

[0058] (2) Add 2.5 mol / L hydrochloric acid solution (solid-liquid ratio 4 mL / g) and 18 g tartaric acid (mass ratio 0.6) to the first leaching residue, and perform complexation leaching at 65℃ and 100 rpm for 80 min. Filter and treat the residue.

[0059] Test results: Step (1) Neutral leaching: Zinc leaching rate 75.18%, Germanium leaching rate 1.67%, Indium leaching rate 0.23%, Tin leaching rate 0.00038%; Step (2) Coordination leaching: Germanium leaching rate 96.89%, indium leaching rate 95.74%, tin leaching rate 86.3%; The elemental composition (wt%) of the second leaching residue is as follows: Zn 11.25, Pb 50.43, Sn 2.31, Ge 0.0138, In 0.0105, Ag 0.0716.

[0060] Comparative Example 1 The only difference from Example 1 is that (1) Take 30g of zinc smelting waste residue (zinc oxide dust) and dry it for later use; set the temperature of the constant temperature magnetic stirring equipment to room temperature and the speed to 100rpm, add 150mL of sulfuric acid solution with a concentration of 100g / L and 2mL of hydrogen peroxide, control the potential to above 630mV, add zinc oxide dust after stirring evenly, and carry out controlled potential neutral leaching. In the first 30min after the start of leaching, use a peristaltic pump to continuously input 5.1mL of hydrogen peroxide into the equipment. After the hydrogen peroxide is delivered, continue leaching for 20min.

[0061] After leaching, the mixed system is filtered and separated to obtain a first leaching solution containing zinc sulfate and a first leaching residue. The first leaching residue is washed twice with water, and the washing liquid is combined with the first leaching solution.

[0062] (2) The washed first leaching residue was placed back into a constant temperature magnetic stirrer, and a hydrochloric acid solution with a mass-to-volume ratio of 4 mL:1 g and a concentration of 3 mol / L was added, along with tartaric acid solid with a mass-to-volume ratio of 0.33:1. Coordination leaching was carried out at 90℃ and 100 rpm. Leaching was completed after 90 min. The mixture was filtered to obtain a second leaching solution containing germanium, indium, and tin, and a second leaching residue containing lead and silver. The second leaching residue was dried in a vacuum drying oven at 60℃ for 12 h.

[0063] The leaching rates of zinc, germanium, indium and tin during the controlled potential neutral leaching process in step (1) were 9.28%, 37.16%, 2.37% and 0.00006%, respectively.

[0064] The results showed that without ultrasound, some germanium and indium could be dissolved in a leaching solution.

[0065] Comparative Example 2 (1) Take 30g of zinc smelting waste residue (zinc oxide dust) and dry it for later use; set the temperature of the constant temperature magnetic stirring equipment to room temperature and the speed to 100rpm, add 150mL of sulfuric acid solution with a concentration of 100g / L and 2mL of hydrogen peroxide, control the potential to above 630mV, add zinc oxide dust after stirring evenly, set the ultrasonic power to 450W, and carry out controlled potential neutral leaching. In the first 30min after the start of leaching, use a peristaltic pump to continuously input 5.1mL of hydrogen peroxide into the equipment. After the hydrogen peroxide is delivered, continue leaching for 20min.

[0066] After leaching, the mixed system is filtered and separated to obtain a first leaching solution containing zinc sulfate and a first leaching residue. The first leaching residue is washed twice with water, and the washing liquid is combined with the first leaching solution.

[0067] (2) The washed first leaching residue was placed back into a constant temperature magnetic stirrer, and water (instead of the hydrochloric acid solution in Example 1) with a mass-to-volume ratio of 4 mL:1 g was added, along with tartaric acid solid with a mass-to-volume ratio of 0.33:1. The second leaching was carried out at 90°C and 100 rpm. The leaching was completed after 90 min. The mixture was filtered to obtain a second leaching solution containing germanium, indium, and tin, and a second leaching residue containing lead and silver. The second leaching residue was dried in a vacuum drying oven at 60°C for 12 h.

[0068] The leaching rates of germanium, indium, and tin in the second leaching process in step (2) were 85.25%, 91.77%, 89.02%, and 78.74%, respectively. The results indicate that without the addition of hydrochloric acid in the second leaching process, some zinc, germanium, indium, and tin will be coated with lead sulfate generated from the first stage of lead sulfide, thus preventing leaching.

[0069] Comparative Example 3 (1) Take 30g of zinc smelting waste residue (zinc oxide dust) and dry it for later use; set the temperature of the constant temperature magnetic stirring equipment to room temperature and the speed to 100rpm, add 150mL of sulfuric acid solution with a concentration of 100g / L and 2mL of hydrogen peroxide, control the potential to above 630mV, add zinc oxide dust after stirring evenly, set the ultrasonic power to 450W, and carry out controlled potential neutral leaching. In the first 30min after the start of leaching, use a peristaltic pump to continuously input 5.1mL of hydrogen peroxide into the equipment. After the hydrogen peroxide is delivered, continue leaching for 20min.

[0070] After leaching, the mixed system is filtered and separated to obtain a first leaching solution containing zinc sulfate and a first leaching residue. The first leaching residue is washed twice with water, and the washing liquid is combined with the first leaching solution.

[0071] (2) The washed first leaching residue was placed back into a constant temperature magnetic stirring device, and a hydrochloric acid solution with a mass-to-volume ratio of 4 mL:1 g and a concentration of 3 mol / L was added. The second leaching was carried out at 90℃ and 100 rpm. The leaching was completed after 90 min. The mixture was filtered to obtain a second leaching solution containing germanium, indium, and tin, and a second leaching residue containing lead and silver. The second leaching residue was dried in a vacuum drying oven at 60℃ for 12 h.

[0072] The leaching rates of germanium, indium, and tin in the second leaching process in step (2) were 83.37%, 82.55%, 70.24%, and 51.26%, respectively.

[0073] The results show that it is not feasible to leach germanium, indium, and tin partially by hydrochloric acid alone without adding tartaric acid during the two-stage leaching process. This is mainly because the strong coordination properties of tartaric acid can promote more germanium, indium, and tin to undergo coordination reactions with tartaric acid.

[0074] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the protection scope of the claims of the present invention.

Claims

1. A method for selectively leaching zinc, germanium, indium, and tin from zinc smelting waste slag in stages, characterized in that, Includes the following steps: 1) After mixing hydrogen peroxide and sulfuric acid solution, add zinc smelting waste residue and perform controlled potential neutral leaching under ultrasonic action to obtain the first leaching residue and the first leaching solution. 2) The first leaching residue obtained in step 1) is mixed with hydrochloric acid and tartaric acid for complexation leaching to obtain the second leaching residue and the second filtrate; The first leachate contains zinc sulfate; The second leachate contains germanium ions, indium ions, and tin ions; The second leaching residue contains lead and silver; The zinc smelting waste residue is zinc oxide dust.

2. The method for selectively leaching zinc, germanium, indium, and tin from zinc smelting waste slag according to claim 1, characterized in that, The concentration of the sulfuric acid solution mentioned in step 1) is 100~160 g / L; The solid-liquid ratio of the sulfuric acid solution to the zinc smelting waste residue is 2.5~6.5 mL / g; The solid-liquid ratio of the hydrogen peroxide to the zinc smelting waste residue is 0.017~0.17 mL / g.

3. The method for selectively leaching zinc, germanium, indium, and tin from zinc smelting waste slag according to claim 2, characterized in that, The power of the ultrasonic wave mentioned in step 1) is 120~600W; The initial redox potential for controlled-potential neutral leaching is 630~695mV, and the leaching time is 30~180min.

4. The method for selectively leaching zinc, germanium, indium, and tin from zinc smelting waste slag according to claim 3, characterized in that, In step 1), hydrogen peroxide is continuously supplied to the system during the controlled potential neutral leaching process from the start of leaching until 20 minutes before the end of leaching. The total amount of hydrogen peroxide delivered is 0.17~1.17 mL / g, which is the solid-liquid ratio of zinc smelting waste.

5. The method for selectively leaching zinc, germanium, indium, and tin from zinc smelting waste slag according to claim 4, characterized in that, The concentration of hydrochloric acid mentioned in step 2) is 0.5~4 mol / L; The solid-liquid ratio of the hydrochloric acid to the first leaching residue is 4 mL / g; The mass ratio of tartaric acid to initial zinc smelting waste is 0.17~0.

83.

6. The method for selectively leaching zinc, germanium, indium, and tin from zinc smelting waste slag according to claim 5, characterized in that, The temperature for coordination leaching in step 2) is 50~90℃, and the leaching time is 20~120min.

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