Method for removing trace impurity selenium in zinc hydrometallurgy solution through in-situ adsorption

Abstract

The invention relates to the technical field of zinc hydrometallurgy, in particular to a method for removing trace impurity selenium in a zinc hydrometallurgy solution through in-situ adsorption, which comprises the following steps: S1, adding a strong oxidant into the zinc hydrometallurgy solution containing low-valence Mn < 2 + > ions, and oxidizing the Mn < 2 + > ions to generate MnO2 precipitate; and S2, adsorbing and removing trace impurity selenium in the solution by using high-activity MnO2 generated by in-situ oxidation. The method has a high removal rate (the highest removal rate can reach 98.46%, and the selenium concentration can reach 20 ng / ml or below) for the trace selenium (1-10 mg / L) in the liquid after zinc powder replacement, does not need additional chemical reagents except the oxidizing agent, is easy and convenient to operate, low in treatment cost, suitable for in-situ efficient removal of the trace impurity selenium in zinc hydrometallurgy production, capable of improving the purity of the zinc electrodeposition liquid and environmentally friendly, and the method is suitable for in-situ efficient removal of the trace impurity selenium in zinc hydrometallurgy production and capable of improving the purity of the zinc electrodeposition liquid.

Description

Technical Field

[0001] The invention relates to the technical field of hydrometallurgical zinc smelting, and in particular to a method for removing trace impurity selenium in a hydrometallurgical zinc smelting solution by in-situ adsorption. Background Art

[0002] Hydrometallurgy is one of the important ways to produce zinc. In the process of hydrometallurgy, the quality of zinc sulfate solution directly affects the quality of the final zinc product and the energy consumption of zinc electrowinning. There is often a trace amount of impurity selenium in the zinc sulfate solution. Although the content is very low, it will circulate and enrich during the electrowinning process. When it reaches a certain concentration, it will cause serious harm to the electrowinning process, such as reducing current efficiency, increasing energy consumption, uneven zinc deposition, etc., thereby reducing the quality and economic benefits of zinc products. Therefore, it is necessary to remove the selenium impurity in the hydrometallurgy solution as much as possible.

[0003] At present, there are many problems with common methods for removing selenium. For example, the alloy powder replacement method is costly because it requires the use of multiple precious metals to make alloy powders, and the process is complex and has strict requirements on equipment and operation. The roasting method consumes a lot of energy, has specific requirements for the composition and properties of zinc concentrate, and produces a large amount of flue gas and smoke during the treatment process. It needs to be equipped with complex flue gas treatment equipment. At the same time, the removal effect of selenium that has entered the solution is limited, and it often needs to be used in combination with other methods. The adsorbent of the adsorption method has limited adsorption capacity and needs to be frequently replaced or regenerated, which increases the operating cost and complexity, and has poor selective adsorption capacity for multiple impurities. The solvent extraction method is difficult to select the extractant. The use of a large amount of organic solvents may not only cause environmental pollution, but also require additional recovery and treatment equipment. The operation process is also relatively complicated and requires precise control of various parameters. The amount of precipitant used in the precipitation method is difficult to accurately control, which can easily lead to incomplete precipitation or the introduction of new impurities. The purity of the resulting precipitate is not high, and the removal effect of low-concentration selenium solution is not ideal.

[0004] In the hydrometallurgical zinc solution, manganese ion is one of the common ions. 2+ Ionic oxidation generates MnO2 precipitation. The in-situ generated MnO2 has good activity and a large surface area. During the precipitation process, it can be used as an in-situ adsorbent to remove trace selenium impurities in the solution. This method makes full use of the existing components in the solution and avoids the introduction of additional complex substances, providing a new, efficient and economical way to remove trace selenium impurities in hydrometallurgical zinc solutions.

[0005] The existing Chinese patent document CN202011033373.0 discloses a method for deep removal of selenium from zinc sulfate solution, including (1) preparation of alloy powder, (2) replacement, (3) reduced pressure heating, and (4) filtration and slag removal; the metal powder includes Mn, Ag, Pt, Re, Bi, and Au; the preparation of specific alloy powder (containing metals such as Mn, Ag, Pt, Re, Bi, and Au) is carried out through replacement, reduced pressure heating, filtration and impurity removal to remove selenium. The principle is to use alloy powder to react with selenium under specific conditions to form precipitates or other forms of insoluble matter for removal; however, a large amount of alloy powder or adsorbent needs to be introduced, which introduces new impurity sources while removing selenium impurities; it is mainly suitable for treating zinc sulfate solutions with relatively high selenium content (0.5-3g / L), and the selenium concentration in the solution is 0.98mg / L when the removal rate reaches the highest.

[0006] The existing Chinese patent document CN201810180406.0 discloses a method for removing trace amounts of selenium and tellurium from zinc sulfate solution by adsorption and precipitation. Under a pressurized environment, ozone is used to oxidize low-valent selenium and tellurium in the zinc sulfate solution to generate high-valent selenium and tellurium, which are then adsorbed by the hydroxide generated by the hydrolysis reaction in the added composite adsorbent, and finally condensed and precipitated under the action of a magnetic field, thereby achieving the purpose of removing selenium and tellurium. The key point is to remove the two impurities of selenium and tellurium through the combined action of pressurized oxidation, composite adsorption and magnetic field precipitation; it needs to be carried out under extraordinary pressure, and requires additional pressurization or decompression devices, which increases the overall cost; the removal efficiency of selenium can reach up to 95.21%, and the selenium concentration in the solution is 0.18mg / L at this time.

[0007] In view of the existing problems, the present invention proposes a method for removing trace impurities of selenium in a wet zinc smelting solution by in-situ oxidation precipitation. 2+ Add a strong oxidant (ozone or hydrogen peroxide) to the original zinc sulfate solution to convert the low-valent Mn 2+ Ionic oxidation generates MnO2 precipitation, and the in-situ generated high-activity MnO2 is used to adsorb and remove trace selenium impurities in the solution. In the present invention, except for the introduction of a strong oxidant, no chemical reagent is added, and the ozone or hydrogen peroxide introduced is a green strong oxidant. The excess oxidant will automatically decompose into oxygen or water, and will not cause any adverse effects on the subsequent zinc electrowinning process or the surrounding environment. At the same time, the present invention is completed under normal pressure, and no additional pressurization or decompression device is required. Summary of the invention

[0008] The purpose of the present invention is to provide a method for removing trace impurity selenium in a wet zinc smelting solution by adsorption using an in-situ oxidation precipitation method, so as to solve the above-mentioned problems of low efficiency, high cost, and complex process flow.

[0009] In order to achieve the above technical objectives and the above technical effects, the present invention is implemented through the following technical solutions:

[0010] A method for removing trace impurities of selenium in a hydrometallurgical zinc smelting solution by in-situ adsorption comprises the following steps:

[0011] S1: To contain low-priced Mn 2+ A strong oxidant is added to the hydrometallurgical zinc solution to remove Mn 2+ Ions are oxidized to form MnO2 precipitate;

[0012] S2: Use the highly active MnO2 generated by in-situ oxidation to adsorb and remove trace impurities of selenium in the solution.

[0013] Furthermore, the S1 hydrometallurgical zinc solution is a zinc powder replacement solution, and its components are trace Se concentration of 1 to 10 mg / L, Zn 2+ Concentration 100~180g / L, low price Mn 2+ Ion concentration: 4-6g / L.

[0014] Furthermore, the constant reaction temperature in S1 is 20-50°C.

[0015] Furthermore, the strong oxidant in S1 includes but is not limited to ozone or hydrogen peroxide.

[0016] Furthermore, the strong oxidant ozone or hydrogen peroxide in S1 and Mn 2+ The molar ratio is 1.2 to 2.4.

[0017] Furthermore, a stirring device should be provided in S1, and stirring should be performed at a stirring rate of 100 to 400 rpm for 10 to 20 min.

[0018] Furthermore, during the adsorption process, the pH of the solution of S2 is maintained at 3 to 6, and the adsorption time is 15 to 60 minutes.

[0019] Beneficial effects of the present invention:

[0020] This technical solution is to add Mn 2+ Introduce a strong oxidant (such as ozone or hydrogen peroxide) into the solution of Mn 2 + Oxidation forms highly active MnO2 precipitate. In this process, Mn 2+The electron cloud structure of the MnO2 changes, and the change of its oxidation state promotes the formation of MnO2 precipitation with special crystal structure and surface chemical properties. This crystal structure has a large specific surface area and can provide a large number of adsorption sites. At the same time, there are abundant active functional groups on the surface of MnO2, such as hydroxyl (-OH). For selenium impurities in the solution, they are mainly removed by two mechanisms: electrostatic adsorption and chemical adsorption. In terms of electrostatic adsorption, since selenium impurities in the solution usually carry a certain charge, they can generate electrostatic attraction with the MnO2 precipitation with opposite charges on the surface (when pH = 5 to 11, its surface charge is negative), which promotes selenium ions to approach and adsorb to the MnO2 surface. In terms of chemical adsorption, selenium ions can react chemically with the active functional groups on the surface of MnO2 to form chemical bonds, which enable selenium ions to be more firmly adsorbed on the MnO2 surface. And because MnO2 is generated in situ, it can better adapt to the chemical environment of the solution and quickly react with selenium impurities. Compared with traditional external adsorbents, it greatly improves the efficiency and effect of selenium removal, thereby effectively ensuring the stability of the zinc electrowinning process and avoiding the reduction in current efficiency and increased energy consumption due to selenium enrichment.

[0021] Since MnO2 is generated in situ, it has high chemical activity and adsorption capacity, which improves the efficiency and effect of selenium removal compared with the traditional adsorption method that requires the use of external adsorbents. Efficient selenium removal not only ensures the stability of the zinc electrowinning process, but also avoids the reduction of current efficiency and increase of energy consumption caused by selenium enrichment.

[0022] The process of the present invention is simple and mainly comprises two steps: oxidation to form MnO2 precipitation and its adsorption to selenium. 2+ , avoiding the additional introduction of high-cost materials, such as the use of precious metal alloy powders, complex precipitants or specific roasting equipment. This not only simplifies the operation process, but also significantly reduces production costs while reducing dependence on specialized equipment. It is worth mentioning that the oxidant (ozone or hydrogen peroxide) used in the process is low-cost and easy to obtain, which further improves the economic efficiency of the method.

[0023] In this process, the strong oxidants used are all environmentally friendly chemical reagents, and there is no use of organic solvents, thus minimizing the risk of environmental pollution. Ozone and hydrogen peroxide decompose into oxygen and water after the reaction, and no harmful by-products are generated, which not only protects the environment but also reduces the pressure on wastewater treatment facilities. In addition, the MnO2 precipitate produced in the process can be easily removed by solid-liquid separation, avoiding the problem of secondary pollution.

[0024] By precisely controlling the reaction conditions such as temperature, oxidant and Mn 2+The molar ratio, stirring rate and pH value of MnO2 can be precisely controlled to precisely regulate the amount of MnO2 generated, crystal structure, surface charge and other properties, ensuring the high selectivity of MnO2 for selenium impurities. Different temperatures will affect the chemical reaction rate and the crystallinity and particle size of MnO2; the oxidant and Mn 2+ The molar ratio determines the amount of MnO2 generated and the degree of oxidation; the stirring rate affects the uniformity of mixing of the substances; and the pH value changes the existence form of ions in the solution and the charge distribution on the surface of MnO2. The combined effect of these factors enables MnO2 to specifically adsorb selenium impurities, with little effect on other impurities and metal ions, which is beneficial to improving the purity and quality of zinc products. This process design fully considers the complex chemical environment of the solution. MnO2 has a strong directional adsorption ability for selenium, but has little effect on other impurities and metal ions, which helps to improve the purity and quality of zinc products. In addition, the flexible adjustability of the reaction parameters provides a high degree of controllability of the process, which can be optimized and adjusted according to actual production conditions to meet the production needs of different scales.

[0025] Of course, any product implementing the present invention does not necessarily need to achieve all of the advantages described above at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for describing the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0027] Figure 1 This is an EDS image of the precipitated slag described in the embodiment of the present invention;

[0028] Figure 2 This is a SEM image of the precipitated slag described in the embodiment of the present invention;

[0029] Figure 3 This is the XRD diagram of the precipitated slag described in the embodiment of the present invention. DETAILED DESCRIPTION

[0030] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] Example 1

[0032] The method for removing trace impurities of selenium in a hydrometallurgical zinc smelting solution by adsorption described in this embodiment comprises:

[0033] Take 1L of selenium-containing zinc sulfate solution and add it to a reactor with constant temperature and constant stirring, the temperature is 50℃, the stirring rate is 100rpm, and the stirring time is 10min. Add strong oxidant ozone or hydrogen peroxide and Mn 2+ The molar ratio is 1.2, and the low-valent Mn 2+ The ions are oxidized in situ to generate MnO2 precipitate. After the oxidation is completed, an appropriate amount of acid or alkali is added to the solution through a pH adjustment device to adjust the pH value of the solution to 6.0. The solution is kept at this pH for 15 minutes to allow the in situ generated MnO2 precipitate to adsorb selenium impurities. During the adsorption process, the reactor is kept stationary to avoid external interference. After the adsorption is completed, the content of selenium impurities in the solution is detected by an inductively coupled plasma mass spectrometer. The results show that the selenium removal rate in zinc sulfate solution is as high as 92.31%.

[0034] Example 2

[0035] The method for removing trace impurities of selenium in a hydrometallurgical zinc smelting solution by adsorption described in this embodiment comprises:

[0036] Take 1L of selenium-containing zinc sulfate solution and add it to a reactor with constant temperature and constant stirring, the temperature is 40℃, the stirring rate is 200rpm, and the stirring time is 10min. Add strong oxidant ozone or hydrogen peroxide and Mn 2+ The molar ratio is 1.6, and the low-valent Mn 2+ The ions are oxidized in situ to generate MnO2 precipitate. After the oxidation is completed, an appropriate amount of acid or alkali is added to the solution through a pH adjustment device to adjust the pH value of the solution to 4.5. The solution is kept at this pH for 30 minutes to allow the in situ generated MnO2 precipitate to adsorb selenium impurities. During the adsorption process, the reactor is kept stationary to avoid external interference. After the adsorption is completed, the content of selenium impurities in the solution is detected by an inductively coupled plasma mass spectrometer. The results show that the selenium removal rate in zinc sulfate solution is as high as 95.52%.

[0037] Example 3

[0038] The method for removing trace impurities of selenium in a hydrometallurgical zinc smelting solution by adsorption described in this embodiment comprises:

[0039] Take 1L of selenium-containing zinc sulfate solution and add it to a reactor with constant temperature and constant stirring speed, the temperature is 30℃, the stirring speed is 300rpm, and the stirring time is 20min. Add strong oxidant ozone or hydrogen peroxide and Mn 2+ The molar ratio is 2.0, and the low-valent Mn 2+The ions are oxidized in situ to generate MnO2 precipitate. After the oxidation is completed, an appropriate amount of acid or alkali is added to the solution through a pH adjustment device to adjust the pH value of the solution to 4.5. The solution is kept at this pH for 45 minutes to allow the in situ generated MnO2 precipitate to adsorb selenium impurities. During the adsorption process, the reactor is kept stationary to avoid external interference. After the adsorption is completed, the content of selenium impurities in the solution is detected by an inductively coupled plasma mass spectrometer. The results show that the selenium removal rate in zinc sulfate solution is as high as 96.27%.

[0040] Example 4

[0041] The method for removing trace impurities of selenium in a hydrometallurgical zinc smelting solution by adsorption described in this embodiment comprises:

[0042] Take 1L of selenium-containing zinc sulfate solution and add it to a reactor with constant temperature and constant stirring, the temperature is 20℃, the stirring rate is 400rpm, and the stirring time is 20min. Add strong oxidant ozone or hydrogen peroxide and Mn 2+ The molar ratio is 2.4, and the low-valent Mn 2+ The ions are oxidized in situ to generate MnO2 precipitate. After the oxidation is completed, an appropriate amount of acid or alkali is added to the solution through a pH adjustment device to adjust the pH value of the solution to 3.0. The solution is kept at this pH for 60 minutes to allow the in situ generated MnO2 precipitate to adsorb selenium impurities. During the adsorption process, the reactor is kept stationary to avoid external interference. After the adsorption is completed, the content of selenium impurities in the solution is detected by an inductively coupled plasma mass spectrometer. The results show that the selenium removal rate in zinc sulfate solution is as high as 98.46%.

[0043] In summary, the present invention proposes a method for removing trace impurities of selenium in a hydrometallurgical zinc solution by in-situ adsorption, which significantly reduces costs, requires only a strong oxidant (ozone or hydrogen peroxide), and utilizes manganese ions originally present in the solution, without the need to add additional chemical reagents such as adsorbents, thereby reducing the cost of chemical agents and having a simple process. The present invention has a high removal rate (up to 98.46%, and the selenium concentration can reach less than 20ng / ml) for trace selenium (1-10mg / L) in the solution after zinc powder replacement, which is significantly better than the prior art.

[0044] The preferred embodiments of the present invention disclosed above are only used to help illustrate the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to the specific implementation methods described. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for removing trace impurities of selenium in a hydrometallurgical zinc solution by in-situ adsorption, characterized in that: The following steps are involved: S1: To contain low-priced Mn 2+ A strong oxidant is added to the hydrometallurgical zinc solution to remove Mn 2+ Ions are oxidized to form MnO2 precipitate; S2: Use the highly active MnO2 generated by in-situ oxidation to adsorb and remove trace impurities of selenium in the solution.

2. The method for removing trace impurities of selenium in a hydrometallurgical zinc solution by in-situ adsorption according to claim 1, characterized in that: The S1 wet zinc smelting solution is a zinc powder replacement solution, including: Se concentration 1-10 mg / L, Zn 2+ Concentration 100~180g / L, Mn 2+ Ion concentration: 4-6g / L.

3. The method for removing trace impurities of selenium in a hydrometallurgical zinc solution by in-situ adsorption as claimed in claim 1, characterized in that: The constant reaction temperature in S1 is 20-50°C.

4. The method for removing trace impurities of selenium in a hydrometallurgical zinc solution by in-situ adsorption as claimed in claim 1, characterized in that: The strong oxidant in S1 includes but is not limited to ozone or hydrogen peroxide.

5. The method for removing trace impurities of selenium in a hydrometallurgical zinc solution by in-situ adsorption as claimed in claim 1, characterized in that: The strong oxidant in S1 and Mn 2+ The molar ratio is 1.2 to 2.

4.

6. The method for removing trace impurities of selenium in a hydrometallurgical zinc solution by in-situ adsorption as claimed in claim 1, characterized in that: A stirring device should be provided in S1, and stirring should be performed at a stirring rate of 100 to 400 rpm for 10 to 20 min.

7. The in-situ adsorption method for removing trace impurities in a hydrometallurgical zinc solution as claimed in claim 1 The method of selenium, characterized in that: The S2 keeps the solution pH at 3-6 during the adsorption process. The adsorption time is 15 to 60 minutes.

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