Preparation method of catalyst for extracting molybdenum, iron and zinc from copper smelting tailings

Abstract

The invention relates to the technical field of comprehensive utilization of solid waste resources and catalysts, and provides a preparation method of a catalyst for extracting molybdenum, iron and zinc from copper smelting tailings. The method comprises the following steps: mixing silicon dioxide, sodium hydroxide and sodium sulfide according to a molar ratio of 1: (1.5-3): (0.8-2), then mixing with N, N-dimethylformamide according to a solid-to-liquid ratio of 1: (6-8), and carrying out solvothermal reaction at 180-220 DEG C under the oxygen pressure of 5-8 MPa for 3-5 hours; and cooling, filtering, washing and drying the reaction product, and calcining in a nitrogen atmosphere at 300-500 DEG C for 1.5-2.5 h to obtain the catalyst. According to the method, through regulation and control of carrier modification, sulfur source introduction and metal complexing, a sulfide active center is effectively formed, sulfur loss is inhibited, the obtained catalyst is used for copper smelting tailing treatment, molybdenum, iron and zinc can be efficiently extracted, the molybdenum leaching rate is larger than 90%, the zinc leaching rate is larger than 85%, the iron ore concentrate grade is larger than 55%, and the iron ore concentrate grade is larger than 55%. The method has the advantages of high metal recovery rate, environment-friendly process and good catalyst stability.

Description

Technical Field

[0001] This invention belongs to the field of catalyst preparation technology, specifically relating to a method for preparing a catalyst for extracting molybdenum, iron, and zinc from copper smelting tailings. Background Technology

[0002] With the increasing global demand for resources and the continuous tightening of environmental policies, the efficient extraction of valuable metals such as molybdenum, iron, and zinc from copper smelting tailings has become a research hotspot in the field of resource recycling. Molybdenum, iron, and zinc, as important strategic metals, are widely used in key industries such as metallurgy, new energy, and chemicals.

[0003] With the continued growth in global demand for strategic metal resources and increasingly stringent environmental protection requirements, recovering valuable metals from secondary resources has become an important way to alleviate resource shortages and promote the development of a circular economy. Copper smelting tailings, as a typical metallurgical solid waste, contains high-grade valuable elements such as molybdenum, iron, and zinc, and has significant comprehensive utilization value. However, due to its complex mineral composition, diverse metal occurrence states, and frequent association with gangue minerals such as silicates, traditional physical beneficiation or direct wet leaching methods often suffer from problems such as low metal recovery rates, high energy consumption, and significant environmental pollution.

[0004] In the extraction technology of metals such as molybdenum, iron, and zinc, early research focused primarily on high-temperature roasting-leaching processes. For example, patent US3455677A proposed roasting sulfide concentrates in a sulfidating atmosphere to convert molybdenum into water-soluble molybdates, thereby achieving copper-molybdenum separation. However, this method has poor adaptability to raw materials, limited effectiveness in processing smelting tailings with complex compositions and fine particle sizes, and high-temperature processes consume a lot of energy and easily generate harmful gases such as sulfur dioxide. Although hydrometallurgical technology has advantages such as mild reaction conditions and good selectivity, direct acid or alkali leaching often results in low metal leaching rates due to severe mineral encapsulation.

[0005] In recent years, catalytic leaching technology has attracted widespread attention due to its ability to enhance interfacial reactivity and improve metal dissolution efficiency. (María Luisa) The research in the paper "Recovery of Zinc and Copper from MineTailings by Acid Leaching Solutions Combined with Carbon-Based Materials" shows that introducing porous carbon-based materials such as activated carbon and charcoal into the acid leaching system can promote the dissolution of copper and zinc in tailings, providing a new approach for developing low-cost, high-efficiency catalytic extraction processes. Furthermore, the construction of catalyst supports and active centers has become a research hotspot. For example, patent CN1078096C discloses a method for preparing a catalyst using silica as a support to support heteropolyacids, but its application is mainly in chemical catalytic reactions, which differs significantly from the extraction requirements of valuable metals from complex mineral systems.

[0006] In catalyst design, transition metal sulfides have shown potential in hydrometallurgy due to their good catalytic activity and stability. Patent CN112899723B provides a metal-organic framework-derived iron-nickel sulfide catalyst for the electrocatalytic oxygen evolution reaction (OER), whose abundant mesoporous structure and tunable active sites offer insights for rational catalyst design. However, the preparation process for this type of catalyst is lengthy and costly, and its application in extracting valuable metals from copper smelting tailings has not yet been disclosed.

[0007] Current research on extracting molybdenum, iron, and zinc from copper smelting tailings faces multiple challenges, including: 1) the complex composition of the tailings, with molybdenum, iron, and zinc minerals often closely associated with gangue minerals, making it difficult for traditional separation methods to achieve efficient dissociation and selective extraction; 2) high energy consumption and significant environmental risks associated with high-temperature or strong-acid processes; and 3) existing catalysts generally suffer from high preparation costs, poor cycle stability, and weak adaptability to complex systems, and the metal recovery rate is unstable during extraction, with significant differences in treatment effects for tailings from different sources. Therefore, developing efficient, green, and economical extraction technologies to improve metal recovery rates and product purity has become a key research direction for alleviating resource shortages and promoting the green transformation of the smelting industry. Summary of the Invention

[0008] To address the aforementioned problems in the existing technology, this invention provides a method for preparing a catalyst for extracting molybdenum, iron, and zinc from copper smelting tailings, comprising the following steps:

[0009] Silica, sodium hydroxide, and sodium sulfide are mixed in a molar ratio of 1:(1.5-3):(0.8-2) to obtain a mixture. The mixture is then mixed with N,N-dimethylformamide in a solid-liquid ratio of 1:(6-8) and reacted for 3-5 hours under an oxygen atmosphere, a pressure of 5-8 MPa, and a temperature of 180-220°C to obtain a reaction product. The reaction product is cooled and then filtered, washed, and dried sequentially. The dried material is calcined at 300-500°C for 1.5-2.5 hours under a nitrogen atmosphere to obtain the catalyst.

[0010] Furthermore, the filtration is either vacuum filtration or pressure filtration.

[0011] Furthermore, the vacuum degree of the vacuum filtration is -0.08 to -0.1 MPa, and the pressure of the pressure filtration is 0.2 to 0.5 MPa.

[0012] Furthermore, the solvent used for washing is selected from one or more of deionized water, ethanol, and acetone.

[0013] Furthermore, the drying process is either atmospheric pressure drying or vacuum drying.

[0014] Furthermore, the atmospheric pressure drying conditions are 80–100°C and drying time is 6–12 h; the vacuum drying conditions are 60–80°C, vacuum degree is -0.095 to -0.1 MPa, and drying time is 4–8 h.

[0015] The present invention also provides a catalyst for extracting molybdenum, iron and zinc from copper smelting tailings, which is obtained by the above preparation method. The catalyst uses silica as a support and has sulfur-containing active centers loaded on the surface of the support.

[0016] Furthermore, the sulfur-containing active centers include MoS2 and / or FeS2.

[0017] This invention also provides a method for extracting molybdenum, iron, and zinc from copper smelting tailings, comprising: adding the aforementioned catalyst at 5-10 wt% of the copper smelting tailings, mixing, and then granulating; roasting the granulated material at 650-900℃ for 1.5-2 hours to obtain a roasted product; grinding the roasted product, adding a sodium hydroxide solution with a concentration of 50-100 g / L, and leaching at a liquid-to-solid ratio of (3-7):1 and a temperature of 80-85℃ for 0.5-2 hours to extract molybdenum and zinc; and magnetically separating the leaching residue to obtain iron concentrate.

[0018] The technical solution of the present invention has the following advantages compared with the prior art:

[0019] (1) Excellent catalyst performance: SiO2 is used as a porous support, and NaOH is used to adjust the degree of hydroxylation on its surface. Sulfur source is introduced through Na2S to form sulfide active centers (such as MoS2, FeS2, etc.). N,N-dimethylformamide is used as a complexing agent, which has the effect of stabilizing metal intermediates and helps to prevent sulfur loss.

[0020] (2) Mild process conditions: The catalyst is prepared by solvothermal reaction, which reduces the processing temperature by 400-800℃, which helps to reduce process energy consumption and avoids the loss of active sites caused by high-temperature sintering.

[0021] (3) High extraction efficiency: The prepared catalyst has stable extraction performance of molybdenum, iron and zinc under high alkali and high temperature conditions, with a molybdenum leaching rate of more than 90%, a zinc leaching rate of more than 85%, and iron finally exists in the form of iron concentrate with a grade of more than 55%, thus realizing the efficient separation and enrichment of molybdenum, iron and zinc in copper smelting tailings.

[0022] (4) Environmentally friendly: It avoids the selective limitations of traditional acid leaching methods on specific metals, reduces the risk of environmental pollution, and achieves efficient separation and enrichment of molybdenum, iron and zinc in copper smelting tailings.

[0023] (5) Wide range of applications: It realizes the resource utilization of copper smelting tailings, alleviates the shortage of strategic metal resources, and promotes the green transformation of the smelting industry. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of protection of this invention.

[0025] Example 1

[0026] Weigh 60g of silicon dioxide, 48g of sodium hydroxide, and 31.2g of sodium sulfide (molar ratio approximately 1:1.5:0.8), and grind them thoroughly in a mixer for 10 minutes. Then, mix the resulting powder with 360mL of N,N-dimethylformamide (DMF) at a solid-liquid ratio of 1:6 (g / mL), transfer the mixture to a 500mL high-pressure reactor for a solvothermal reaction, seal the reactor, and introduce high-purity oxygen until the system pressure reaches 8MPa. Then, increase the temperature to 180℃ at a rate of 5℃ / min and stir the reaction for 3 hours.

[0027] After the reaction was completed, the mixture was allowed to cool naturally to room temperature, and the reactor was opened after depressurization. The reaction product was vacuum filtered using a Buchner funnel (vacuum degree -0.09 MPa). The resulting solid filter cake was washed three times each with 500 mL of deionized water and 200 mL of anhydrous ethanol. The washed solid was transferred to a vacuum drying oven and dried at 60 °C and -0.1 MPa for 5 h. Finally, the dried precursor powder was placed in a tube furnace and calcined at 300 °C under a nitrogen atmosphere at a rate of 5 °C / min for 2.5 h. After cooling with the furnace, the powder was removed, ground, and passed through a 200-mesh sieve to obtain the target catalyst, denoted as Cat-1.

[0028] Performance evaluation of catalyst Cat-1: 100g of copper smelting tailings (containing 0.39% Mo, 1.9% Zn, and 57.5% Fe) was crushed and ground to a particle size of less than 74μm. It was then mixed evenly with 10wt% of catalyst Cat-2, granulated, and the granules were calcined in a muffle furnace at 700℃ for 2 hours. The calcined clinker was ground again to -100 mesh and leached for 2 hours at a liquid-to-solid ratio of 4:1 (mL / g) and a temperature of 85℃ with 100g / L NaOH solution. After the reaction, solid-liquid separation was performed, and the metal concentration in the solution was analyzed using ICP-OES to calculate the leaching rate. The leaching residue was then magnetically separated to enrich iron, and the iron concentrate grade was analyzed.

[0029] The results showed that the leaching rate of molybdenum was 95.8%, the leaching rate of zinc was 75.9%, and the grade of iron concentrate in the leaching residue reached 56.8%, achieving efficient separation and enrichment of valuable metals.

[0030] Example 2

[0031] Weigh out 60g of silica, 64g of sodium hydroxide, and 58.5g of sodium sulfide (molar ratio approximately 1:2:1.5), mix thoroughly, and then add to a high-pressure reactor with 420mL of N,N-dimethylformamide at a solid-liquid ratio of 1:7 (g / mL). Purge with oxygen to a pressure of 7MPa, program the temperature to 200℃, and stir for 4 hours. After cooling, filter under vacuum at -0.08MPa. Wash the filter cake with deionized water until the filtrate is neutral. Place the solid in a vacuum drying oven and dry at 70℃ and -0.095MPa for 4 hours. Calcinate the dried material at 400℃ for 2 hours under a nitrogen atmosphere with a heating rate of 5℃ / min to obtain the target catalyst, denoted as Cat-2.

[0032] Performance evaluation of catalyst Cat-2: 100g of copper smelting tailings (containing 1.2% Mo, 3.5% Zn, and 35.6% Fe) was crushed and ground to a particle size of less than 74μm. This was then thoroughly mixed with 7.5wt% Cat-2 catalyst, granulated, and the granules were calcined in a muffle furnace at 650℃ for 2 hours. The calcined clinker was then ground again to -100 mesh and leached for 0.3 hours at a liquid-to-solid ratio of 7:1 (mL / g) and a temperature of 85℃ using a 50g / L NaOH solution. After the reaction, solid-liquid separation was performed, and the metal concentration in the solution was analyzed using ICP-OES to calculate the leaching rate. The leaching residue was then magnetically separated to enrich iron, and the iron concentrate grade was analyzed.

[0033] The results showed that the leaching rate of molybdenum was 92.5%, the leaching rate of zinc was 87.3%, and the grade of iron concentrate in the leaching residue reached 57.1%.

[0034] Example 3

[0035] 60g of silica, 96g of sodium hydroxide, and 78g of sodium sulfide (molar ratio approximately 1:3:2) were weighed and mixed, then added to a high-pressure reactor with 480mL of N,N-dimethylformamide (solid-liquid ratio 1:8 g / mL). Oxygen was introduced to 5MPa, and the temperature was raised to 220℃ for 5h. After cooling, the solid was separated by pressure filtration (0.3MPa) and washed three times successively with deionized water and acetone. The solid was placed in a forced-air drying oven and dried at 80℃ and normal pressure for 6h. Finally, it was calcined at 500℃ for 1.5h under a nitrogen atmosphere with a heating rate of 5℃ / min to obtain catalyst Cat-3.

[0036] Performance evaluation of catalyst Cat-3: 100g of copper smelting tailings (containing 0.21% Mo, 2.3% Zn, and 55.6% Fe) was crushed and ground to a particle size of less than 75μm, and thoroughly mixed with 5wt% Cat-3 catalyst. The mixture was then briquetteed and granulated, and the granules were calcined in a muffle furnace at 900℃ for 1.5h. The calcined clinker was ground again to -100 mesh, and leached for 1h at a liquid-to-solid ratio of 3:1 (mL / g) and a temperature of 80℃ with 50g / L NaOH solution. After the reaction, solid-liquid separation was performed, and the metal concentration in the solution was analyzed using ICP-OES to calculate the leaching rate. The leaching residue was then magnetically separated to enrich iron, and the iron concentrate grade was analyzed.

[0037] The results showed that the leaching rate of molybdenum was 96.5%, the leaching rate of zinc was 80.9%, and the grade of iron concentrate in the leaching residue reached 56.2%.

[0038] Comparative Example 1

[0039] A combined pyrometallurgical smelting and beneficiation process was used to treat copper smelting tailings. 100g of the same batch of copper smelting tailings as in the previous example was mixed with limestone and coke powder in a certain proportion and smelted at a high temperature of 1500–1600℃. This reduced the iron oxides in the copper slag to molten iron, enriching copper as crude copper. The smelting product was then subjected to flotation, magnetic separation, and other beneficiation operations. The results showed that the copper recovery rate was 80%, the iron recovery rate was approximately 76%, but the zinc recovery rate was only 35%, and the process was extremely energy-intensive.

[0040] Comparative Example 2

[0041] Microbial leaching technology was used to treat copper smelting tailings. 100g of the same batch of copper smelting tailings was placed in a leaching medium containing *Thiobacillus ferrooxidans*, with an initial pH of 2.5, and leached for 30 days under normal temperature and pressure conditions. The final copper leaching rate was 66%, the zinc leaching rate was 51%, and the iron leaching rate was less than 20%. Furthermore, the reaction cycle was too long and the efficiency was low.

[0042] Comparative Example 3

[0043] 100g of copper smelting tailings from the same batch was directly granulated and calcined at 650℃ for 2 hours without the addition of any catalyst. The calcined clinker was leached for 30 minutes under alkaline conditions (50g / L NaOH, 80℃, liquid-to-solid ratio 7:1). The results showed that the molybdenum leaching rate was only 68.2%, the zinc leaching rate was 62.5%, and the iron concentrate obtained by magnetic separation of the leaching residue had a grade of only 48.3%. This demonstrates that the catalyst of this invention plays a key promoting role in the efficient extraction of metals.

[0044] The above examples and comparative examples fully illustrate that the catalyst preparation method provided by the present invention is feasible and has good repeatability. The prepared catalyst can significantly enhance the extraction efficiency of molybdenum, iron and zinc in copper smelting tailings. It has outstanding advantages such as relatively mild reaction conditions, high metal recovery rate and environmental friendliness, and has good prospects for industrial application.

[0045] The above-described embodiments are preferred embodiments of the present invention. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A method for preparing a catalyst for extracting molybdenum, iron, and zinc from copper smelting tailings, characterized in that, Includes the following steps: Silica, sodium hydroxide, and sodium sulfide are mixed in a molar ratio of 1:(1.5~3):(0.8~2) to obtain a mixture. The mixture was mixed with N,N-dimethylformamide at a solid-liquid ratio of 1:(6-8), and reacted for 3-5 hours under an oxygen atmosphere, a pressure of 5-8 MPa, and a temperature of 180-220°C to obtain the reaction product. The reaction products were cooled and then sequentially filtered, washed, and dried. The dried material was calcined at 300–500°C for 1.5–2.5 h under a nitrogen atmosphere to obtain the catalyst.

2. The preparation method according to claim 1, characterized in that, The filtration is either vacuum filtration or pressure filtration.

3. The preparation method according to claim 2, characterized in that, The vacuum degree of the vacuum filtration is -0.08 to -0.1 MPa, and the pressure of the pressure filtration is 0.2 to 0.5 MPa.

4. The preparation method according to claim 1, characterized in that, The solvent used for washing is selected from one or more of deionized water, ethanol, and acetone.

5. The preparation method according to claim 1, characterized in that, The drying process can be either atmospheric pressure drying or vacuum drying.

6. The preparation method according to claim 5, characterized in that, The temperature for atmospheric drying is 80–100℃, and the drying time is 6–12 h; the temperature for vacuum drying is 60–80℃, the vacuum degree is -0.095 to -0.1 MPa, and the drying time is 4–8 h.

7. A catalyst for extracting molybdenum, iron, and zinc from copper smelting tailings, characterized in that, The catalyst is prepared by the method according to any one of claims 1 to 6, wherein the catalyst uses silica as a support and sulfur-containing active centers are loaded on the surface of the support.

8. The catalyst according to claim 7, characterized in that, The sulfur-containing active centers include MoS2 and / or FeS2.

9. A method for extracting molybdenum, iron, and zinc from copper smelting tailings, characterized in that, Includes the following steps: The catalyst described in claim 7 or 8 is added at 5-10 wt% of copper smelting tailings, mixed, and then granulated. The granulated material is calcined at 650–900℃ for 1.5–2 hours to obtain the calcined product. After grinding the roasted product, a sodium hydroxide solution with a concentration of 50-100 g / L is added, and leaching is carried out for 0.5-2 hours at a liquid-to-solid ratio of (3-7):1 and a temperature of 80-85℃ to achieve the extraction of molybdenum and zinc. The leaching residue is separated by magnetic separation to obtain iron concentrate.