Method for strengthening leaching of zinc and germanium in zinc leaching residues through cooperation of ultrasonic waves and tartaric acid

Abstract

The invention relates to a method for strengthening leaching of zinc and germanium in zinc leaching residues through cooperation of ultrasonic waves and tartaric acid, and belongs to the technical field of hydrometallurgy. When the zinc leaching residues are leached, tartaric acid is added to serve as a reducing agent, an ultrasonic wave external field is introduced in the reduction leaching process, the concentration of dilute sulphuric acid is controlled to be 1.7-2.1 mol / L, the adding amount of tartaric acid is 0.16-0.72 mol / L, and the leaching time of the zinc and germanium is shortened; the liquid-solid ratio is 4: 1-8: 1, in the leaching process, tartaric acid and zinc and germanium ions form a stable complex, the zinc and germanium leaching rate is effectively increased, the used reducing agent is safe and non-toxic and has high leaching selectivity, the content of impurities in the leachate is low, and the slag yield is low.

Description

Technical Field

[0001] The present invention belongs to the technical field of hydrometallurgy. Specifically, it relates to a method for enhancing the leaching of zinc and germanium from zinc leaching residues by ultrasonic wave synergistic tartaric acid. Background Technique

[0002] The production process of zinc is roughly divided into pyrometallurgy and hydrometallurgy. Due to problems such as high environmental pollution and low comprehensive metal recovery rate in pyrometallurgy, about 80% of zinc globally is produced by hydrometallurgy. Hydrometallurgy usually includes two main steps: converting zinc concentrate into zinc calcine or zinc fume through roasting, and then extracting zinc through acid leaching. The obtained zinc sulfate solution is sent to an electrolytic cell for electrowinning after purification treatment, and finally zinc metal is obtained.

[0003] The zinc leaching residues generated during the hydrometallurgy process contain valuable metals such as zinc and germanium, and have important recovery value. However, the mineral composition of zinc leaching residues is complex, and some components have high chemical stability and poor solubility under acidic conditions, resulting in difficult metal recovery. In addition, iron and other metals (such as germanium) are prone to form insoluble complexes during the leaching process, further inhibiting the efficient leaching of zinc and germanium.

[0004] In order to improve the leaching rate of zinc and germanium, many researchers have proposed adding reducing agents during the leaching process to promote the dissolution of insoluble substances, thereby improving the leaching rate of zinc and germanium. Commonly used reducing agents include hydrogen, carbon monoxide, hydrogen sulfide, ferrous sulfate, etc. By reducing chemically stable elements with reducing agents, their mineral structures are changed, their solubility is improved, and thus the leaching efficiency of zinc and germanium is increased. However, traditional reducing agents also have some disadvantages. For example, although hydrogen has strong reducing ability as a reducing agent, it usually requires a relatively high temperature and a long reaction time, which increases energy consumption and reaction costs; carbon monoxide will release CO gas during the reaction, and the generated precipitates will increase the subsequent treatment difficulty; hydrogen sulfide is toxic and corrosive, and strict safety control is required during use, and sulfide precipitates may be generated, increasing the subsequent treatment burden; ferrous sulfate has a slow reaction rate and generates a large amount of iron precipitates, increasing the subsequent cleaning work. Summary of the Invention

[0005] In order to overcome the problems existing in the background technique, the present invention provides a method for enhancing the leaching of zinc and germanium from zinc leaching residues by ultrasonic wave synergistic tartaric acid. Using tartaric acid as a reducing agent and introducing an ultrasonic external field during the reduction leaching process can effectively improve the leaching rate of zinc and germanium. The used reducing agent is safe, non-toxic, has high leaching selectivity, and has a low slag production.

[0006] To achieve the above object, the present invention is realized through the following technical solutions: The described method for enhancing the leaching of zinc and germanium from zinc leaching residue by ultrasonic wave synergistic tartaric acid uses dilute sulfuric acid as a solvent and adds tartaric acid as a reducing agent to leach the zinc leaching residue under the action of an ultrasonic external field.

[0007] Furthermore, the concentration of the dilute sulfuric acid is 1.7 - 2.1 mol / L, and the addition amount of tartaric acid is 0.16 - 0.72 mol / L.

[0008] Furthermore, the liquid - solid ratio of the dilute sulfuric acid to the zinc leaching residue is 4:1 - 8:1.

[0009] Furthermore, the leaching time is 90 - 180 min, and the leaching temperature is 50 - 90 °C.

[0010] Furthermore, the ultrasonic power is 100 - 600 W.

[0011] Furthermore, the zinc leaching residue refers to the neutral or acidic leaching residue generated in the process of hydrometallurgical zinc extraction.

[0012] Compared with the prior art, the present invention has the following advantages and technical effects: In the present invention, tartaric acid is added during the leaching process, and ultrasonic technology is combined to enhance the leaching of zinc (Zn) and germanium (Ge) from zinc leaching residue. Tartaric acid can achieve efficient and selective leaching of zinc and germanium, without introducing impurities and with moderate cost. Ultrasonic technology, through mechanical vibration, cavitation effect and micro - fluid dynamics effect, significantly enhances the interaction between tartaric acid and metal particles. The local high temperature and high pressure generated by its cavitation effect can destroy the metal surface oxide layer and coating layer, promote the direct contact between tartaric acid and zinc and germanium, and strengthen the complexation of tartaric acid with zinc and germanium; at the same time, the strongly oxidizing free radicals generated by ultrasound can further promote the oxidation and dissolution of metals, enhancing the leaching effect. In addition, the micro - fluid dynamics effect of ultrasound can also strengthen the solution mixing and mass transfer, significantly improving the leaching efficiency and shortening the leaching time. This synergistic effect not only improves the leaching rates of zinc and germanium, but also improves the economy and environmental friendliness of the leaching process of zinc leaching residue, providing an efficient and green new method for the high - efficient recovery of valuable metals from zinc leaching residue. Description of the Drawings

[0013] Figure 1 is the process flow schematic diagram of the present invention; Figure 2 is the XRD pattern of the zinc leaching residue raw material used in the embodiment of the present invention; Figure 3 is the SEM - EDS image of the zinc leaching residue raw material used in the embodiment of the present invention; Figure 4 is the comparison of the SEM images of the leaching residues of Comparative Example 1 and Example 1, where (a) - (c) are the SEM images of Comparative Example 1, and (d) - (e) are the SEM images of Example 1; Figure 5 EDS images and elemental distributions of the leaching residues of Comparative Example 1 and Example 1, where A is the EDS image and elemental distribution of the leaching residue of Comparative Example 1, and B is the EDS image and elemental distribution of Example 1; Figure 6 XRD patterns of the leaching residues of Example 1 and Comparative Example 1; Figure 7 Infrared comparison diagrams of the leaching residues of Example 1 and Comparative Example 1. Detailed implementation manners

[0014] In order to make the objectives, technical solutions and beneficial effects of the present invention clearer, the technical solutions of the present invention will be described in detail below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, other embodiments obtained by those skilled in the art without creative efforts fall within the scope of protection of the present invention.

[0015] The method for ultrasonic wave synergistic tartaric acid to enhance the leaching of zinc and germanium from zinc leaching residue specifically is as follows: First, crush the zinc leaching residue, use dilute sulfuric acid as a solvent, add tartaric acid as a reducing agent, and carry out leaching under the action of an ultrasonic external field. The concentration of dilute sulfuric acid is 1.7 - 2.1 mol / L, the addition amount of tartaric acid is 0.16 - 0.72 mol / L, and the liquid-solid ratio of dilute sulfuric acid to zinc leaching residue is 4:1 - 8:1; the leaching time is 90 - 180 min, the leaching temperature is 50 - 90 °C, and the ultrasonic power is 100 - 600 W.

[0016] The present invention uses tartaric acid as a reducing agent. Tartaric acid has good economy and a wide range of raw material sources, with a moderate cost and is suitable for industrial application.

[0017] Using tartaric acid as a reducing agent for leaching zinc leaching residue can effectively improve the solubility of zinc and germanium. It can be judged from the experimental phenomena during the leaching process that tartaric acid forms stable complexes with zinc and germanium ions. The leaching results show that tartaric acid has good selectivity. Ultrasonic waves can strengthen the leaching process and accelerate the complexation of tartaric acid with metal ions, significantly improving the leaching rate of metals. Ultrasonic waves can also reduce the influence of insoluble minerals such as zinc ferrite in the zinc leaching residue, strip the coating layer, and overcome the problem of low recovery rate in the traditional leaching process. In addition, ultrasonic waves can promote the redox reaction in the solution and further improve the leaching efficiency of metals. Through the synergistic effect of tartaric acid and ultrasonic waves, the present invention not only shortens the leaching reaction time, reduces the amount of wet residue, but also reduces the cost of subsequent treatment, having good economy.

[0018] To illustrate the present invention more clearly, the following examples are used for detailed description. Example 1

[0019] Weigh 30 g of zinc leaching residue that has been dried, pulverized, and sieved through 180 meshes (hereinafter referred to as zinc leaching residue raw material to avoid confusion). The XRD pattern of the dried zinc leaching residue raw material is as shown in Figure 2 Figure []. The SEM-EDS image of the zinc leaching residue raw material is as shown in Figure 3 Figure []. It can be seen from Figure 3 that the main chemical components of the zinc leaching residue raw material are iron, zinc, lead, sulfur, calcium, silicon, and oxygen. It is observed that the spatial distributions of iron, zinc, and oxygen elements show a high degree of correlation, indicating that this sample area contains a significant amount of zinc ferrite minerals. Similarly, lead, calcium, sulfur, and oxygen have a common distribution characteristic, suggesting the possibility of the existence of lead sulfate (PbSO4) and calcium sulfate (CaSO4). In addition, there are also similarities in the distributions of zinc, oxygen, and silicon elements, providing a basis for the existence of compounds such as silicon dioxide (SiO2) or zinc silicate (Zn2SiO4).

[0020] Measure dilute sulfuric acid with an acidity of 2 mol / L. Mix the dilute sulfuric acid with the zinc leaching residue raw material at a liquid-solid ratio of 7 ml / g. Add tartaric acid in an amount of 0.30 - 0.60 mol / L. Carry out ultrasonic leaching under the condition of constant temperature at 50 - 90 °C. The ultrasonic power is 300 W. Control the stirring speed at 80 - 100 r / min and leach for 180 min. After leaching, filter, dry the filter residue, and obtain 14.96 g of dry-based filter residue. The XRD of the dry-based filter residue is as shown by the blue line in Figure 6 Figure []. After analysis, in the leaching solution, the contents of zinc and germanium are 31.56 g / L and 33.37 mg / L respectively, and the leaching rates of zinc and germanium are 83.96% and 89.59% respectively. The XRD of the dried filter residue is as shown by the blue line in Figure 6 Figure [].

[0021] Comparative Example 1 In this comparative example, except for not using ultrasonic waves, the treatment raw materials and experimental conditions are the same as those in Example 1. The leached filter residue is fully dried to obtain 20.47 g of dry-based filter residue. The XRD of the dry-based filter residue is as shown by the red line in Figure 6 Figure []. In the leaching solution, the contents of zinc and germanium are 17.96 g / L and 24.62 mg / L respectively, and the leaching rates of zinc and germanium are 74.64% and 60.69% respectively. The results show that without ultrasonic waves, the leaching rates of zinc and germanium decrease.

[0022] By Figure 2 and Figure 6It can be seen that compared with the zinc leaching residue raw material and the leaching residue of Comparative Example 1, the main components of both are PbSO4 and CaSO4, accompanied by a small amount of ZnS and ZnFe2O4. Compared with the zinc leaching residue raw material, the main phase of zinc ferrite still significantly exists in the leaching residue of this comparative example. However, the characteristic peak intensity of zinc ferrite in the leaching residue of Example 1 is significantly reduced or almost disappears, indicating that ultrasonic wave synergistic with tartaric acid can effectively destroy the structure of zinc ferrite, thereby achieving its efficient leaching. It should be noted that in the leaching residue of ultrasonic wave synergistic with tartaric acid reduction leaching (the leaching residue of Example 1), the peak intensities of lead sulfate and calcium sulfate are much higher than those of the leaching residue of Comparative Example 1, indicating that the method of the present invention promotes the effective release of a large number of minerals. The residual zinc sulfide is not completely removed during the leaching process, and this phenomenon can be attributed to the fact that sulfides need to be fully dissolved under specific acidic and oxidation conditions. The XRD analysis results strongly prove that the ultrasonic wave synergistic with tartaric acid leaching method shows excellent efficiency in the extraction of zinc and germanium.

[0023] Figure 4 SEM images of the leaching residues of Comparative Example 1 and Example 1 are shown. Among them, (a)-(c) are SEM images of the leaching residue of Comparative Example 1, and (d)-(e) are SEM images of the leaching residue of Example 1; it can be seen from Figure 4 that the surface characteristics of the leaching residue of Comparative Example 1 ( Figure 4 region 1 in a and Figure 4 region 2 in b) appear relatively smooth and do not show significant signs of reaction. While the surface of the leaching residue of Example 1 ( Figure 4 region 3 in d) presents a rough and uneven morphology with obvious erosion marks, indicating a high degree of looseness on its surface. This different morphology is attributed to the combined effect of ultrasonic wave and tartaric acid, which promotes the minerals to undergo reduction to form sulfates, or directly through physical fragmentation under the action of ultrasonic wave, resulting in the disintegration and exposure of mineral inclusions. Comparing Figure 4 c with Figure 4 d and Figure 4 e, the mineral particles in the leaching residue of Example 1 show a more dispersed state, while the aggregation of minerals in the leaching residue of Comparative Example 1 may limit the effective progress of the leaching reaction, which is one of the factors for its lower leaching efficiency. This further proves the superiority of ultrasonic wave synergistic with tartaric acid treatment in improving the leaching efficiency.

[0024] Figure 5 EDS images and element distributions of the leaching residues of Comparative Example 1 and Example 1 are shown. Among them, Figure A is the EDS image and element distribution of the leaching residue of Comparative Example 1, and Figure B is the EDS image and element distribution of the leaching residue of Example 1. For Figure 5The results of the elemental distribution analysis in regions 5a and 5e show that the leaching residues of Comparative Example 1 and Example 1 are both rich in lead compounds. Combining the spatial distribution characteristics of lead, sulfur, and oxygen elements, it can be inferred that these elements mainly exist in the form of lead sulfate. In addition, the distribution characteristics of sulfur, oxygen, and calcium also imply the presence of calcium sulfate. By analyzing the distribution of iron, zinc, and oxygen, it is found that the signal intensities of these elements in the leaching residue of Example 1 are significantly weaker than those in the leaching residue of Comparative Example 1, while the concentrations of lead, silicon, sulfur, and calcium have increased significantly. This finding is consistent with the XRD analysis results, further verifying the unique efficacy of ultrasonic waves combined with tartaric acid in promoting the efficient leaching of zinc and germanium.

[0025] Comparative Example 2 (Comparison of leaching rates of different reducing agents without ultrasonic waves) In this comparative example, different reducing agents were selected to leach the zinc leaching residue with the same dosage and the same reaction conditions, as follows: Weigh 30 g of zinc leaching residue raw materials that have been crushed, dried, and screened through a 200-mesh sieve. Control the initial acidity to 1.8 mol / L and the liquid-solid ratio to 7 mL / g. Add the zinc leaching residue and dilute sulfuric acid to the reactor, and add tartaric acid, formic acid, citric acid, and thiourea in an amount of 0.48 mol / L respectively. Under constant temperature stirring at 90 °C, control the rotation speed to 80 - 100 r / min, and the leaching time to 180 min. After leaching, filter, dry the filter residue at 60 °C for 15 h, weigh and detect the filtrate and the filter residue, and calculate the leaching rates of zinc and germanium to obtain the leaching conditions using different reducing agents.

[0026] Table 1 Effects of different reducing agents on the leaching rates of zinc and germanium (without ultrasonic waves)

[0027] Using tartaric acid as the reducing agent, the amount of residue produced is the lowest, and the leaching rate of germanium is the highest.

[0028] Example 2 (Comparison of leaching rates of different reducing agents under ultrasonic waves)

[0029] In this example, different reducing agents were selected to leach the zinc leaching residue with the same dosage and the same reaction conditions under the action of an ultrasonic external field, as follows: Weigh 30 g of zinc leaching residue raw materials that have been crushed, dried, and screened through a 200-mesh sieve. Control the initial acidity to 1.8 mol / L and the liquid-solid ratio to 7 mL / g. Add the zinc leaching residue and dilute sulfuric acid to the reactor, and add tartaric acid, formic acid, citric acid, and thiourea in an amount of 0.48 mol / L respectively. Under constant temperature stirring at 90 °C, control the rotation speed to 80 - 100 r / min, and under the action of 300 W ultrasonic waves, the leaching time is 180 min. After leaching, filter, dry the filter residue at 60 °C for 15 h, weigh and detect the filtrate and the filter residue, and calculate the leaching rates of zinc and germanium to obtain the leaching conditions using different reducing agents.

[0030] Table 2 Influence of Different Reducing Agents on the Leaching Rates of Zinc and Germanium (Ultrasonic)

[0031] By comparing Comparative Example 2 and Example 2, it was found that without ultrasonic, when leaching with a reducing agent, in the case of using tartaric acid as the reducing agent, the leaching rate of germanium (65.47%) was higher than that of other reducing agents; with ultrasonic, when leaching with a reducing agent, the zinc leaching rate (83.96%) and germanium leaching rate (89.59%) of tartaric acid were significantly higher than those of other reducing agents. This indicates that ultrasonic-assisted leaching significantly improves the leaching effect of tartaric acid, making it superior to other reducing agents in terms of the leaching rates of zinc and germanium. Especially, there is also an obvious increase in the leaching of zinc, which is very likely that ultrasonic enhances the complexation of tartaric acid with zinc, or ultrasonic promotes the dissolution of some zinc compounds that are difficult to leach. Example 3

[0032] Weigh 30 g of zinc leaching residue raw material dried and sieved through a 200-mesh sieve, control the initial acidity to be 2 mol / L, and the liquid-solid ratio to be 7 mL / g. Add dilute sulfuric acid and zinc leaching residue to the reactor, and add tartaric acid in an amount of 0.16 mol / L. Under constant temperature stirring at 90 °C, control the rotation speed to be 80 - 100 r / min, and under the action of 600 W ultrasonic waves, the leaching time is 180 min. After leaching, filter, dry the filter residue at 60 °C for 15 h. The contents of zinc and germanium in the filtrate are 18.66 g / L and 29.55 mg / L respectively, and the zinc and germanium leaching rates are 77.5% and 69.01% respectively. Example 4

[0033] Weigh 30 g of zinc leaching residue dried and sieved through a 200-mesh sieve, and then weigh 0.72 mol / L of tartaric acid. Mix the two and place them in the reactor, and then add sulfuric acid solution to the container, control the initial acidity to be 2 mol / L, and the liquid-solid ratio to be 7 mL / g. Under constant temperature stirring at 90 °C, control the rotation speed to be 80 - 100 r / min, and under the action of 300 W ultrasonic waves, the leaching time is 180 min. After leaching, filter, dry the filter residue at 60 °C for 15 h. The zinc and germanium leaching rates are 83.60% and 84.15% respectively.

[0034] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention rather than to limit them. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made in form and details without departing from the scope defined by the claims of the present invention.

Claims

1. A method for enhancing the extraction of zinc and germanium from zinc leaching residue by ultrasonic wave synergistic tartaric acid, characterized in that, Using dilute sulfuric acid as a solvent and adding tartaric acid, zinc leaching residue is leached under the action of an ultrasonic external field.

2. The method for enhancing zinc and germanium leaching from zinc leaching residue by using ultrasound and tartaric acid according to claim 1, characterized in that: The concentration of the dilute sulfuric acid is 1.7 - 2.1 mol / L, and the addition amount of tartaric acid is 0.16 - 0.72 mol / L.

3. The method for enhancing the leaching of zinc and germanium from zinc leaching residue by ultrasonic wave synergistic tartaric acid according to claim 1 or 2, characterized in that, The liquid-solid ratio of the dilute sulfuric acid to the zinc leaching residue is 4:1 - 8:

1.

4. The method for enhancing the leaching of zinc and germanium from zinc leaching residue by ultrasonic wave synergistic tartaric acid according to claim 3, characterized in that, The leaching time is 90 - 180 min, and the leaching temperature is 50 - 90 °C.

5. The method for enhancing the leaching of zinc and germanium from zinc leaching residue by ultrasonic wave synergistic tartaric acid according to claim 3, characterized in that, The ultrasonic power is 100 - 600 W.

6. The method for enhancing the leaching of zinc and germanium from zinc leaching residue by ultrasonic wave synergistic tartaric acid according to claim 1, wherein The zinc leaching residue mentioned refers to the neutral or acidic leaching residue generated in the process of zinc hydrometallurgy.

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