A method for strengthening the reduction leaching of zinc sulfide concentrate refining zinc hydrometallurgy residue
Patent Information
- Application Number
- CN202610317655.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-03-16
- Publication Date
- 2026-09-25
AI Technical Summary
在协同浸出过程中，具有一定的还原作用，但存在的不足是硫化锌精矿消耗量大、浸出渣含锌高、有机、无机还原物质的利用率低，或者高价态离子还原程度较低等不足，如何提高湿法炼锌渣还原浸出效率，减少硫化锌精矿等试剂消耗，降低还原浸出渣含锌是湿法炼锌领域需要解决的技术难题
[0032]（1）本方法采用富氮气体进行惰性保护，促进硫化锌精矿中还原性有机质、活性硫化物与浸出矿浆中三价铁的还原反应进行，提高了硫化锌精矿中还原性物质的利用效率，强化硫化锌精矿还原反应，大幅提升了硫化锌精矿还原浸出反应效率。
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Figure CN122811536A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a method for enhancing the reduction leaching of zinc smelting slag from zinc sulfide concentrate in hydrometallurgical processes, belonging to the field of metallurgical engineering technology. Background Technology
[0002] Hydrometallurgical zinc smelting is currently the main zinc smelting method both domestically and internationally, producing over 85% of the world's metallic zinc. A typical hydrometallurgical zinc smelting process mainly includes fluidized bed roasting of zinc sulfide concentrate, neutral leaching of the roasted ore, low-acid leaching, neutral leachate purification, electrowinning, and casting. The hydrometallurgical slag produced during the leaching process is typically treated with high-temperature pyrometallurgical reduction volatilization using equipment such as rotary kilns or fuming furnaces to achieve harmless disposal and comprehensive recovery of associated valuable metals; or it can be treated using high-temperature, high-acid leaching or other hydrometallurgical methods.
[0003] The principle of high-temperature pyrometallurgical reduction and volatilization of zinc slag in hydrometallurgical processes is based on the low boiling point of zinc. A carbonaceous reducing agent is used to reduce and volatilize zinc at high temperatures of 1100℃~1350℃. The volatilized metal vapor is further oxidized by oxygen in the flue gas into metal oxides, which are then collected as zinc oxide dust, achieving comprehensive recovery of zinc and various metals. Typical pyrometallurgical treatment technologies include rotary kiln process, fuming process, and Kifset process. Besides pyrometallurgical processes, hydrometallurgical leaching is also an effective method. Currently, hydrometallurgical treatment processes for zinc leaching slag include high-temperature high-acid leaching, sulfur dioxide reduction leaching, and co-leaching of zinc sulfide concentrate. There have been many reports on the co-leaching of zinc sulfide concentrate and hydrometallurgical zinc slag (e.g., "Co-leaching of zinc and indium from zinc leaching slag and zinc sulfide concentrate", Zhang Fan et al., Nonferrous Metals Engineering, 2016, 6(03); "Research on the co-leaching mechanism and process of hydrometallurgical zinc leaching slag and high-iron zinc concentrate", Zhang Fan, Kunming University of Science and Technology, 2017.05; "Co-leaching and oxidation conversion behavior of zinc concentrate and zinc leaching slag", Fu Zhongmeng et al., Chinese Journal of Nonferrous Metals, 2028, 28(10); "Co-leaching mechanism and behavior of zinc sulfide concentrate and zinc leaching slag", Li Changwen et al., Journal of Central South University, 2023, 54(02)). While it has a certain reducing effect during the co-leaching process, it has shortcomings such as high consumption of zinc sulfide concentrate, high zinc content in the leaching residue, low utilization rate of organic and inorganic reducing substances, or low degree of reduction of high-valence ions. How to improve the reduction leaching efficiency of zinc sulfide concentrate and other reagents, and reduce the zinc content in the reduction leaching residue are technical problems that need to be solved in the field of hydrometallurgical zinc refining. Summary of the Invention
[0004] To overcome the problems and shortcomings of the prior art, this invention provides a method for enhancing the reduction leaching of zinc smelting slag from zinc sulfide concentrate. This invention employs a nitrogen-rich gas at appropriate pressure to protect against and inhibit excessive oxidation, allowing the reaction to proceed in stages. This promotes the reduction reaction between reducing organic matter and active sulfides in the zinc sulfide concentrate and ferric ions in the leaching slurry, reducing them to ferrous ions. Simultaneously, by increasing the partial pressure of nitrogen and decreasing the partial pressure of oxygen in the gas, the oxidizing capacity of the introduced gas is reduced at the nitrogen-rich gas source, preventing secondary oxidation of low-valence ions in the reaction products. This improves the reduction reaction efficiency, reduces the consumption of zinc sulfide concentrate, and enhances the reduction leaching process of zinc sulfide concentrate on zinc leaching slag. In this invention, nitrogen-rich gas is used to control the reaction pressure to increase the solubility of reducing substances in the reaction slurry and improve the reduction reaction efficiency. Too low a reaction pressure reduces the solubility of reducing substances, decreasing reaction efficiency; too high a pressure lowers the partial pressure of reducing substances, hindering the reduction reaction. Therefore, conducting the reaction in stages under the protection of nitrogen-rich gas can enhance the reduction leaching effect, thereby improving the efficiency of the reduction leaching reaction, reducing the consumption of zinc sulfide concentrate, reducing the zinc content in the reduction leaching residue, and increasing the Fe(II) / Fe(III) mass ratio of the leachate.
[0005] To achieve the above objectives, the present invention provides a method for enhancing the reduction leaching of zinc smelting slag from zinc sulfide concentrate, the process comprising the following steps:
[0006] The wet zinc smelting slag was mixed with sulfuric acid solution to form a slurry, controlling the initial sulfuric acid concentration in the slurry to be ≥120 g / L and the liquid-to-solid ratio to be 6~10:1 (unit: mL / g). This slurry was added to a reactor, and nitrogen-rich gas was continuously introduced. Stage I reaction was carried out under the conditions of reaction temperature ≥85℃ and reaction pressure 100~400 kPa. Then, a slurry containing zinc sulfide concentrate was added using a pressure pump, and nitrogen-rich gas was continuously introduced to maintain the reaction pressure at 100~300 kPa. Stage II reaction was carried out under the conditions of reaction temperature ≥90℃. After the reaction, the liquid and solid were separated to obtain reduction leaching residue and reduction leaching solution. The nitrogen-rich gas had a nitrogen gas fraction of ≥82%, preferably 82~95%, and more preferably 82~92%, including 82~90%. During the exploration process, it was found that pure nitrogen gas would affect the zinc leaching rate and it was difficult to achieve a Fe(II) / Fe(III) mass ratio greater than or equal to 48.
[0007] In the nitrogen-rich gas, the volume fraction of oxygen is less than 18%, more preferably less than or equal to 17%, including less than or equal to 15%.
[0008] Furthermore, the amount of zinc sulfide concentrate added is 0.7~1.0, preferably 0.85~0.95, based on the theoretical reaction stoichiometry. The theoretical reaction equation is: ZnFe2O4 + 4H2SO4 + ZnS = 2ZnSO4 + 2FeSO4 + S + 4H2O.
[0009] Furthermore, the aforementioned hydrometallurgical zinc slag refers to the leaching residue produced during the hydrometallurgical zinc smelting process. Its main phases are zinc ferrite and a small amount of zinc sulfide. The hydrometallurgical zinc slag mainly comprises, by mass percentage: 10-25% zinc, 10-28% iron, and 5-15% sulfur. The hydrometallurgical zinc slag may also contain at least one of the following compounds: silicon dioxide, calcium sulfate, lead sulfate, and water of crystallization.
[0010] Furthermore, the zinc sulfide concentrate mainly comprises, by mass percentage: 40-50% zinc, 5-15% iron, 28-33% sulfur, and 0.5-3% organic matter. The zinc sulfide concentrate may also contain at least one compound of elements such as lead, silicon, and calcium.
[0011] Furthermore, the proportion of the wet zinc smelting slag with a particle size of less than 74μm exceeds 90%.
[0012] Furthermore, the proportion of zinc sulfide concentrate particles smaller than 74μm is greater than 90%.
[0013] Furthermore, the reaction time for stage I is 90-120 minutes.
[0014] Furthermore, the reaction time for stage II is 30-90 minutes.
[0015] The optimized initial sulfuric acid concentration in the slurry is controlled at 120~150 g / L.
[0016] The optimized reaction temperature for stage I is 85-95°C, and the reaction temperature for stage II is 90-105°C.
[0017] As a further preferred option, the reaction temperature for stage I is 88~92℃ and the reaction temperature for stage II is 98~102℃. During the exploration process, it was found that under certain temperature conditions, the Fe(II) / Fe(III) mass ratio can be greater than or equal to 48, and can even reach 80 or above.
[0018] Furthermore, during the Phase II reaction, the pressure of the nitrogen-rich gas is greater than or equal to that during the Phase I reaction, which is beneficial for increasing the solubility of reducing substances in the reaction slurry and improving the efficiency of the reduction reaction.
[0019] Furthermore, during the Phase II reaction, the reaction temperature is higher than that during the Phase I reaction. In this invention, by controlling an appropriate reaction temperature and ensuring that the temperature difference between the Phase II reaction temperature and the Phase I reaction temperature is ≥5°C, this control method helps to avoid the precipitation reaction caused by high concentrations of ferric ions in Phase I, while also increasing the reaction rate of Phase II and accelerating the reduction reaction process.
[0020] Optimized, the sulfuric acid solution is one of the waste electrolyte produced by wet zinc electrolysis, high acid leachate, or a mixture of the two.
[0021] The basic principle of this invention is:
[0022] This invention employs a nitrogen-rich gas at appropriate pressure for protection, and the reaction proceeds in stages to promote the reduction reaction between reducing organic matter and active sulfides in zinc sulfide concentrate and ferric ions in the leaching pulp, reducing them to ferrous ions. In stage I, the main reactions involve the destruction and dissolution of zinc ferrite in the hydrometallurgical zinc slag, as well as the destruction and dissolution of residual zinc sulfide in the hydrometallurgical zinc slag. The main reaction equations are:
[0023] ZnFe2O4+4H2SO4 = ZnSO4 + Fe2(SO4)3+ 4H2O;
[0024] ZnS+ Fe2(SO4)3 = ZnSO4 + 2FeSO4 + S.
[0025] In stage II of the reaction, the main reactions are the reduction of sphalerite (ZnS), iron sphalerite (mZnS•nFeS) in zinc sulfide concentrate, organic reducing agent (RH), inorganic active reducing substance MeS (Me represents Cu, Zn, or Fe) with ferric ions. The main reaction equations are as follows:
[0026] Fe2(SO4)3 + ZnS = ZnSO4+ 2FeSO4 + S;
[0027] Fe2(SO4)3 + mZnS·nFeS = mZnSO4 +(2+n) FeSO4 +(m+n)S;
[0028] Fe2(SO4)3 + RH → 2FeSO4 +CO2+ H2O; Fe2(SO4)3 + MeS = FeSO4+ MeSO4 + S.
[0029] The principle behind this invention, which uses nitrogen-rich gas at appropriate pressure as an inert gas for reductive leaching, is to increase the partial pressure of nitrogen and decrease the partial pressure of oxygen in the gas. This nitrogen-rich gas source reduces the oxidizing capacity of the introduced gas, preventing secondary oxidation of low-valence ions in the reaction products, thereby improving the reduction reaction efficiency. Simultaneously, it reduces the consumption of zinc sulfide concentrate and enhances the reductive leaching process of zinc sulfide concentrate on zinc leaching residue. The main purpose of using nitrogen-rich gas is that nitrogen has a high partial pressure, while oxygen has a low partial pressure. The low oxygen partial pressure is insufficient to oxidize low-valence ions such as divalent iron in the reaction products to high-valence ions, thus avoiding secondary oxidation of low-valence ions. If oxygen or oxygen-enriched air is introduced during the reaction, under high oxygen partial pressure conditions, oxygen participates in the secondary oxidation reaction of low-valence ions, leading to a decrease in reduction efficiency.
[0030] The main principle of this invention, employing a staged reaction, is that during Stage I, the destruction and dissolution of zinc ferrite consumes a large amount of sulfuric acid, achieving the leaching of zinc and iron while simultaneously increasing the concentration of ferric ions in the solution and decreasing the concentration of free sulfuric acid. Stage I provides favorable conditions for Stage II. Firstly, the high concentration of ferric ions in the solution accelerates the reduction reaction of minerals such as sphalerite and ferrosphalerite in the zinc concentrate. Secondly, the lower concentration of sulfuric acid avoids the generation of harmful intermediate gases such as hydrogen sulfide during the reaction process. Therefore, Stage I and Stage II are interconnected and inseparable progressive reactions, collectively enhancing the reduction leaching process of zinc sulfide concentrate on the zinc leaching residue.
[0031] The beneficial effects of this invention are:
[0032] (1) This method uses nitrogen-rich gas for inert protection, which promotes the reduction reaction between reducing organic matter and active sulfides in zinc sulfide concentrate and ferric iron in leaching pulp, improves the utilization efficiency of reducing substances in zinc sulfide concentrate, strengthens the reduction reaction of zinc sulfide concentrate, and greatly improves the reduction leaching reaction efficiency of zinc sulfide concentrate.
[0033] (2) This method eliminates the ineffective consumption of zinc sulfide concentrate by oxidizing substances such as oxygen, improves the effective utilization rate of zinc sulfide concentrate, and in particular improves the reduction effect of residual flotation reagents and other organic matter in zinc sulfide concentrate on ferric ions in leaching pulp, avoids the ineffective consumption of reducing substances by oxygen, and the amount of zinc sulfide concentrate added in the reduction leaching process is only 0.7~1.0 of the theoretical reaction stoichiometry, which greatly reduces the consumption of zinc sulfide concentrate.
[0034] (3) This method requires less zinc sulfide concentrate, has high reaction efficiency, high leaching rate of zinc, iron, etc., low zinc and iron content in the reduction leaching residue, low residue rate, and reduces the output of reduction leaching residue.
[0035] (4) This method uses inert gas protection and staged reaction to enhance the effect. The concentration of ferric ions in the reduced leachate is low, the Fe(II) / Fe(III) mass ratio of the reduced leachate is high, and the overall reduction leaching effect is good. Attached Figure Description
[0036] Figure 1 The image shows the XRD pattern of the wet zinc leaching residue from Example 1.
[0037] Figure 2 The image shows the XRD pattern of the reduced leaching residue obtained in Example 1.
[0038] Figure 3 This is a SEM image of the reduced leaching residue obtained in Example 1. Detailed Implementation
[0039] 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.
[0040] Example 1
[0041] Weigh 100g (dry basis) of wet zinc smelting slag, the main chemical composition of which is 20.1wt% Zn, 25.6wt% iron, 9.2wt% sulfur, 6.5wt% silica, 3.8wt% calcium sulfate, 6.4wt% lead sulfate, with the remainder being water of crystallization, bound oxygen, etc., and 92% of the particles having a particle size of less than 74μm. Weigh 0.9g of zinc sulfide concentrate (with 90% of its particles having a particle size of less than 74μm, containing 45.6% zinc, 9.2% iron, and 31.0% sulfur) according to the theoretical reaction stoichiometry. The slurry was prepared by mixing wet zinc smelting slag with sulfuric acid solution, controlling the initial sulfuric acid concentration in the slurry to be 148 g / L and the liquid-to-solid ratio (mL / g) to be 6:1. This slurry was added to a closed reactor, and then a nitrogen-rich gas with a nitrogen volume fraction of 85% (oxygen volume fraction of 14%, balance being other gaseous impurities) was introduced. Stage I reaction was carried out at 90℃ and 300 kPa, with stirring for 120 min. Afterwards, a slurry containing zinc sulfide concentrate (slurry concentration of 45%) was added using a pressure pump, and a nitrogen-rich gas with a nitrogen volume fraction of 82% was continuously introduced. Stage II reaction was carried out at 100℃ and 300 kPa, with stirring for 90 min. After the reaction, the liquid and solid were separated to obtain a reducing leaching solution and a reducing leaching residue, with a dry weight of 23.2 g for the reducing leaching residue.
[0042] In this embodiment, the zinc leaching rate was 99.2%, the iron leaching rate was 96.5%, the reduction leaching residue contained 0.98% zinc and 4.10% iron; the concentration of ferric ions in the reduction leaching solution was 0.72 g / L, and the Fe(II) / Fe(III) mass ratio was 50.
[0043] Example 1-1
[0044] The raw materials are the same as in Example 1, except that a nitrogen-rich gas with a nitrogen volume fraction of 90% (oxygen volume fraction of 9%, and the remainder being other gaseous impurities) is introduced. In this example, the dry weight of the reductive leaching residue is 23.8 g, the zinc leaching rate is 99.3%, the iron leaching rate is 96.6%, the reductive leaching residue contains 0.87% zinc and 3.90% iron; the concentration of ferric ions in the reductive leaching solution is 0.45 g / L, and the Fe(II) / Fe(III) mass ratio is 80.3.
[0045] Examples 1-2
[0046] The raw materials are the same as in Example 1, except that the reaction temperature for Stage I is 95°C and the reaction temperature for Stage II is 105°C. In this example, the dry weight of the reductive leaching residue is 23.0 g, the zinc leaching rate is 99.4%, the iron leaching rate is 97.4%, and the reductive leaching residue contains 0.80% zinc and 3.1% iron; the concentration of ferric ions in the reductive leaching solution is 0.8 g / L, and the Fe(II) / Fe(III) mass ratio is 45.1.
[0047] Examples 1-3
[0048] The raw materials were the same as in Example 1, except that 0.9 g of zinc sulfide concentrate was added according to the theoretical reaction stoichiometry. Stage I reaction was carried out at 100°C and 200 kPa, with stirring for 90 min. Then, a slurry containing zinc sulfide concentrate (45% concentration) was added using a pressure pump, and nitrogen-rich gas with a nitrogen content of 85% was continuously introduced. Stage II reaction was carried out at 105°C and 300 kPa, with stirring for 60 min.
[0049] In this embodiment, the zinc leaching rate was 99.1%, the iron leaching rate was 96.2%, the reduction leaching residue contained 1.05% zinc and 4.2% iron; the concentration of ferric ions in the reduction leaching solution was 0.90 g / L, and the Fe(II) / Fe(III) mass ratio was 39.
[0050] Comparative Example 1
[0051] The raw materials and other processes and parameters were the same as in Example 1, except that oxygen was introduced throughout the process. In this comparative example, the dry weight of the reduction leaching residue was 38.2 g, the zinc leaching rate was 98.6%, the iron leaching rate was 82.7%, and the reduction leaching residue contained 1.1% zinc and 12.5% iron. The concentration of ferric ions in the reduction leaching solution was 25.7 g / L, and the Fe(II) / Fe(III) mass ratio was 0.22.
[0052] Comparative Example 2
[0053] The raw materials and other processes and parameters were the same as in Example 1, except that air was used throughout the process. In this comparative example, the dry weight of the reductive leaching residue was 30.7 g, the zinc leaching rate was 99.1%, the iron leaching rate was 91.3%, and the reductive leaching residue contained 0.90% zinc and 7.80% iron. The concentration of ferric ions in the reductive leaching solution was 18.5 g / L, and the Fe(II) / Fe(III) mass ratio was 0.87.
[0054] Example 2
[0055] Weigh 100g (dry basis) of wet zinc smelting slag, the main chemical composition of which is 23.2wt% Zn, 23.5wt% iron, 8.2wt% sulfur, 6.9wt% silica, 4.0wt% calcium sulfate, 5.8wt% lead sulfate, with the remainder being water of crystallization, bound oxygen, etc., and 95% of the particles having a particle size of less than 74μm. Weigh 1.0g of zinc sulfide concentrate (with 95% of its particles having a particle size of less than 74μm, containing 46.2% zinc, 10.7% iron, and 31.5% sulfur) according to the theoretical reaction stoichiometry. The slurry was prepared by mixing wet zinc smelting slag with sulfuric acid solution, controlling the initial sulfuric acid concentration in the slurry to be 135 g / L and the liquid-to-solid ratio (mL / g) to be 8:1. This slurry was added to a closed reactor, and then a nitrogen-rich gas with a nitrogen volume fraction of 82% (oxygen volume fraction of 17%, balance being other gaseous impurities) was introduced. Stage I reaction was carried out at 95℃ and 200 kPa, with stirring for 120 min. Afterwards, a slurry containing zinc sulfide concentrate was added using a pressure pump, and a nitrogen-rich gas with a nitrogen volume fraction of 82% was continuously introduced. Stage II reaction was carried out at 100℃ and 200 kPa, with stirring for 90 min. Upon completion of the reaction, the liquid and solid phases were separated to obtain a reducing leaching solution and a reducing leaching residue, with a dry weight of 23.7 g for the reducing leaching residue.
[0056] In this embodiment, the zinc leaching rate was 99.0%, the iron leaching rate was 96.5%, the reduction leaching residue contained 1.45% zinc and 3.80% iron; the concentration of ferric ions in the reduction leaching solution was 0.65 g / L, and the Fe(II) / Fe(III) mass ratio was 38.5.
[0057] Example 2-1
[0058] The raw materials are the same as in Example 2, and the other processes and process parameters are also the same as in Example 2. The difference is:
[0059] The slurry was prepared by mixing wet zinc smelting slag with sulfuric acid solution, controlling the initial sulfuric acid concentration in the slurry to be 135 g / L and the liquid-to-solid ratio (mL / g) to be 8:1. This slurry was added to a closed reactor, and then nitrogen-rich gas (82% nitrogen content, 17% oxygen content, balance being other gaseous impurities) was introduced. Stage I reaction was carried out at 95℃ and 150 kPa, with stirring for 120 min. Afterwards, a slurry containing zinc sulfide concentrate was added using a pressure pump, and nitrogen-rich gas (82% nitrogen content) was continuously introduced. Stage II reaction was carried out at 105℃ and 200 kPa, with stirring for 90 min. Upon completion of the reaction, the liquid and solid phases were separated to obtain a reducing leaching solution and a reducing leaching residue, with a dry weight of 24.2 g for the reducing leaching residue.
[0060] In this embodiment, the zinc leaching rate was 98.9%, the iron leaching rate was 96.0%, the reduction leaching residue contained 1.47% zinc and 4.3% iron; the concentration of ferric ions in the reduction leaching solution was 0.62 g / L, and the Fe(II) / Fe(III) mass ratio was 40.
[0061] Example 2-2
[0062] The raw materials are the same as in Example 2, and the other processes and process parameters are also the same as in Example 2. The difference is:
[0063] The slurry was prepared by mixing wet zinc smelting slag with sulfuric acid solution, controlling the initial sulfuric acid concentration in the slurry to be 135 g / L and the liquid-to-solid ratio (mL / g) to be 8:1. This slurry was added to a closed reactor, and then a nitrogen-rich gas with a nitrogen volume fraction of 82% (oxygen volume fraction of 17%, the remainder being other gaseous impurities) was introduced. Stage I reaction was carried out at 95℃ and 200 kPa, with stirring for 120 min. Afterwards, a slurry containing zinc sulfide concentrate was added using a pressure pump, and a nitrogen-rich gas with a nitrogen volume fraction of 82% was continuously introduced. Stage II reaction was carried out at 95℃ and 200 kPa, with stirring for 90 min. Upon completion of the reaction, the liquid and solid phases were separated to obtain a reducing leaching solution and a reducing leaching residue, with a dry weight of 25.70 g for the reducing leaching residue.
[0064] In this embodiment, the zinc leaching rate was 98.7%, the iron leaching rate was 95.3%, the reduction leaching residue contained 1.71% zinc and 4.70% iron; the concentration of ferric ions in the reduction leaching solution was 0.85 g / L, and the Fe(II) / Fe(III) mass ratio was 29.
[0065] Example 3
[0066] Weigh 100g (dry basis) of wet zinc smelting slag, the main chemical composition of which is 18.2wt% Zn, 26.3wt% iron, 9.5wt% sulfur, 7.8wt% silica, 3.6wt% calcium sulfate, 5.2wt% lead sulfate, with the remainder being water of crystallization, bound oxygen, etc., and 95% of the particles having a particle size of less than 74μm. Weigh 0.7g of zinc sulfide concentrate (with 95% of its particles having a particle size of less than 74μm, containing 45.3% zinc, 14.2% iron, and 32.0% sulfur) according to the theoretical reaction stoichiometry. The slurry was prepared by mixing wet zinc smelting slag with sulfuric acid solution, controlling the initial sulfuric acid concentration in the slurry to be 130 g / L and the liquid-to-solid ratio (mL / g) to be 10:1. This slurry was added to a closed reactor, and then nitrogen-rich gas (88% nitrogen content, 11% oxygen content, balance being other gaseous impurities) was introduced. Stage I reaction was carried out at 85℃ and 150 kPa, with stirring for 120 min. Afterwards, a slurry containing zinc sulfide concentrate was added using a pressure pump, and nitrogen-rich gas (90% nitrogen content) was continuously introduced. Stage II reaction was carried out at 100℃ and 150 kPa, with stirring for 75 min. Upon completion of the reaction, the liquid and solid were separated to obtain a reducing leaching solution and a reducing leaching residue, with a dry weight of 21.42 g for the reducing leaching residue.
[0067] In this embodiment, the zinc leaching rate was 98.8%, the iron leaching rate was 96.0%, the reduction leaching residue contained 1.21% zinc and 4.60% iron; the concentration of ferric ions in the reduction leaching solution was 0.55 g / L, and the Fe(II) / Fe(III) mass ratio was 42.
[0068] Example 3-1
[0069] The raw materials and other processes and parameters were the same as in Example 3, except that a pressure pump was used to add the slurry containing zinc sulfide concentrate, and nitrogen-rich gas with a nitrogen content of 88% was continuously introduced. Stage II reaction was carried out at 100°C and 150 kPa, with stirring for 75 minutes. After the reaction, liquid-solid separation was performed to obtain a reducing leaching solution and a reducing leaching residue, with a dry weight of 24.8 g for the reducing leaching residue.
[0070] In this embodiment, the zinc leaching rate was 98.9%, the iron leaching rate was 96.1%, the reduction leaching residue contained 1.18% zinc and 4.50% iron; the concentration of ferric ions in the reduction leaching solution was 0.67 g / L, and the Fe(II) / Fe(III) mass ratio was 34.
[0071] Exploration Example 1
[0072] The raw materials and other processes and parameters are the same as in Example 3, except that: the wet zinc smelting slag is mixed with sulfuric acid solution to form a slurry, controlling the initial sulfuric acid concentration in the slurry to be 130 g / L and the liquid-to-solid ratio (mL / g) to be 10:1. This slurry is added to a closed reactor, and then pure nitrogen gas is introduced. Stage I reaction is carried out at 85°C and 150 kPa, with stirring for 120 min. Afterwards, a slurry containing zinc sulfide concentrate is added using a pressure pump, and pure nitrogen gas is continuously introduced. Stage II reaction is carried out at 100°C and 150 kPa, with stirring for 75 min. After the reaction, the liquid and solid are separated to obtain a reducing leaching solution and a reducing leaching residue, with a dry weight of 29.6 g for the reducing leaching residue.
[0073] In this exploratory example, the zinc leaching rate was 95.8%, the iron leaching rate was 91.9%, the reduction leaching residue contained 3.65% zinc and 7.80% iron; the concentration of ferric ions in the reduction leaching solution was 0.52 g / L, and the Fe(II) / Fe(III) mass ratio was 42.
[0074] The specific embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.
Claims
1. A method for enhancing the reduction leaching of zinc smelting slag from zinc sulfide concentrate in hydrometallurgical zinc refining, characterized in that... The process includes the following steps: mixing wet zinc smelting slag with sulfuric acid solution to form a slurry, controlling the initial sulfuric acid concentration in the slurry to be ≥120g / L, and the liquid-to-solid ratio to be 6~10:1 (unit: mL / g); adding this slurry to a reactor, continuously introducing nitrogen-rich gas, and carrying out stage I reaction under the conditions of reaction temperature ≥85℃ and reaction pressure 100~400KPa; then adding slurry containing zinc sulfide concentrate using a pressure pump, continuously introducing nitrogen-rich gas to maintain the reaction pressure at 100~300KPa, and carrying out stage II reaction under the conditions of reaction temperature ≥90℃; after the reaction is completed, liquid-solid separation is performed to obtain reduction leaching residue and reduction leaching solution, wherein the nitrogen gas content in the nitrogen-rich gas is ≥82%.
2. The method for enhancing the reduction leaching of zinc smelting slag from zinc sulfide concentrate according to claim 1, characterized in that: The volume fraction of oxygen in the nitrogen-rich gas is less than 18%.
3. The method for enhancing the reduction leaching of zinc smelting slag from zinc sulfide concentrate according to claim 1, characterized in that: The amount of zinc sulfide concentrate added is 0.7 to 1.0 of the theoretical reaction stoichiometry.
4. The method for enhancing the reduction leaching of zinc smelting slag from zinc sulfide concentrate according to claim 1, characterized in that: The hydrometallurgical zinc slag refers to the leaching residue produced in the hydrometallurgical zinc slag process. Its phases include zinc ferrite and zinc sulfide. The hydrometallurgical zinc slag includes, by mass percentage: 10-25% zinc, 10-28% iron, and 5-15% sulfur.
5. The method for enhancing the reduction leaching of zinc smelting slag from zinc sulfide concentrate according to claim 1, characterized in that: The zinc sulfide concentrate has a particle size of less than 74μm accounting for more than 90%, and by mass percentage it includes: zinc 40~50%, iron 5~15%, sulfur 28~33%, and organic matter 0.5%~3%.
6. The method for enhancing the reduction leaching of zinc smelting slag from zinc sulfide concentrate according to claim 1, characterized in that: The proportion of the wet zinc smelting slag with a particle size of less than 74μm exceeds 90%.
7. The method for enhancing the reduction leaching of zinc smelting slag from zinc sulfide concentrate according to claim 1, characterized in that: The reaction temperature for Stage I is 85~95℃, and the reaction temperature for Stage II is 90~105℃.
8. The method for enhancing the reduction leaching of zinc smelting slag from zinc sulfide concentrate according to claim 1, characterized in that: The reaction time for stage I is 90-120 min; the reaction time for stage II is 30-90 min.
9. The method for enhancing the reduction leaching of zinc smelting slag from zinc sulfide concentrate according to claim 1, characterized in that: The initial sulfuric acid concentration in the controlled slurry is 120~150 g / L.
10. A method for enhancing the reduction leaching of zinc smelting slag from zinc sulfide concentrate according to claim 1, characterized in that: The sulfuric acid solution is one of the waste electrolyte produced by wet zinc electrolysis, high acid leaching solution, or a mixture of the two.