Impurity removal method for molybdenum concentrate
By using an alternating acid-base treatment method to remove impurities from molybdenum concentrate, the environmental and safety issues caused by the use of hydrofluoric acid were resolved, enabling the production of high-purity molybdenum disulfide and reducing costs and resource waste.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- HENAN CHEM IND RES INST
- Filing Date
- 2026-02-05
- Publication Date
- 2026-05-08
AI Technical Summary
Existing methods for producing molybdenum disulfide use hydrofluoric acid, which generates fluoride-containing wastewater, impacting the environment and safety. Furthermore, the process is complex and costly.
Acid leaching is performed using hydrochloric acid, sulfuric acid, or nitric acid as acidic solutions, followed by alkaline leaching using sodium hydroxide or potassium hydroxide as alkaline solutions. Hydrofluoric acid should be avoided. Impurities, especially iron and silicon dioxide, in molybdenum concentrate are removed through alternating acid-base treatment.
This achieves fluoride-free wastewater discharge, reduces production risks and costs, improves the purity and market competitiveness of molybdenum disulfide, simplifies the process, and reduces resource waste and environmental pollution.
Smart Images
Figure CN121992227A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of molybdenum disulfide preparation technology, specifically relating to a method for removing impurities from molybdenum concentrate. Background Technology
[0002] Molybdenum disulfide (MoD) is a material with unique properties, playing a vital role in numerous fields ranging from traditional industries to cutting-edge technologies due to its superior characteristics resulting from its layered structure. It can withstand extreme environments, maintaining excellent lubrication performance under high, low, and high vacuum conditions, and is widely used in mechanical lubrication and aerospace. Simultaneously, MoD possesses semiconductor properties, particularly the direct band gap of monolayer MoD, which gives it potential in optoelectronics, optoelectronic devices, and sensors. As a two-dimensional van der Waals material, MoD exhibits a unique layered structure and excellent low-shear properties. In aero-engines, MoD coatings are used for friction reduction and protection of high-temperature components such as turbine blades and bearings.
[0003] Molybdenum disulfide is mainly derived from molybdenite, but the natural ore contains complex impurities such as silicon and iron, requiring deep impurity removal to produce high-quality molybdenum disulfide. Currently, the main production method for molybdenum disulfide is the multi-stage acid leaching method of molybdenum concentrate. First, hydrochloric acid is used to remove impurities such as iron and calcium, and then hydrofluoric acid is used to remove silicon dioxide impurities. However, each process generates a certain amount of acidic wastewater and fluoride-containing wastewater.
[0004] Hydrofluoric acid is a colorless, odorless, and highly corrosive liquid. It is a highly dangerous and toxic inorganic acid that can volatilize at room temperature to form toxic gases, thereby affecting human health. Summary of the Invention
[0005] In view of this, the present invention provides a method for removing impurities from molybdenum concentrate. The method provided by the present invention does not use hydrofluoric acid, thus avoiding the generation of fluoride-containing wastewater and improving the safety of the impurity removal process.
[0006] To solve the above-mentioned technical problems, the present invention provides a method for removing impurities from molybdenum concentrate, comprising the following steps: Molybdenum concentrate is soaked in an acidic solution for acid leaching to obtain crude molybdenum disulfide. The crude molybdenum disulfide is soaked in an alkaline solution for alkaline leaching to obtain pure molybdenum disulfide; the mass concentration of the alkaline solution is 30-50%.
[0007] Preferably, the acidic solution includes hydrochloric acid solution, sulfuric acid solution, or nitric acid solution; the mass concentration of the acidic solution is 25-35%.
[0008] Preferably, the mass ratio of the molybdenum concentrate to the acidic solution is 1:0.8~1.2.
[0009] Preferably, the acid leaching temperature is 75~85℃ and the acid leaching time is 2.5~3.5h.
[0010] Preferably, the acid leaching process further includes: performing a first solid-liquid separation on the acid-leached system, washing the obtained solid with water, and then drying it to obtain crude molybdenum disulfide.
[0011] Preferably, the mass ratio of the alkaline solution to crude molybdenum disulfide is 1:0.1~10.
[0012] Preferably, the alkaline solution includes sodium hydroxide solution and / or potassium hydroxide solution.
[0013] Preferably, the alkaline leaching temperature is 65~125℃ and the time is 5~10h.
[0014] Preferably, the alkaline leaching process further includes: performing a second solid-liquid separation on the alkaline leaching system, and sequentially performing a second water washing and a second drying on the obtained solid.
[0015] Preferably, the molybdenum concentrate contains 19-56.4% molybdenum by mass and 1.5-36.63% silica by mass.
[0016] This invention provides a method for removing impurities from molybdenum concentrate, comprising the following steps: immersing the molybdenum concentrate in an acidic solution for acid leaching to obtain crude molybdenum disulfide; immersing the crude molybdenum disulfide in an alkaline solution for alkaline leaching to obtain pure molybdenum disulfide; wherein the mass concentration of the alkaline solution is 30-50%. This invention removes acid-soluble impurities (such as iron and calcium) from the molybdenum concentrate through acid leaching; then, alkaline leaching is performed in an alkaline solution of a specific concentration to react with silica to generate soluble sodium silicate, thereby removing silica and obtaining high-purity molybdenum disulfide. The impurity removal method provided by this invention does not use hydrofluoric acid, thus eliminating the risks and environmental impacts of hydrofluoric acid use, simplifying the process, and reducing investment and operating costs. Attached Figure Description
[0017] Figure 1 This is a schematic diagram of the process for treating molybdenum concentrate using sodium hydroxide solution as an alkaline solution. Detailed Implementation
[0018] This invention provides a method for removing impurities from molybdenum concentrate, comprising the following steps: Molybdenum concentrate is soaked in an acidic solution for acid leaching to obtain crude molybdenum disulfide. The crude molybdenum disulfide is soaked in an alkaline solution for alkaline leaching to obtain pure molybdenum disulfide; the mass concentration of the alkaline solution is 30-50%.
[0019] This invention involves leaching molybdenum concentrate in an acidic solution to obtain crude molybdenum disulfide. In this invention, the molybdenum concentrate contains 19-56.4% molybdenum by mass, specifically 19.04%, 23%, 30%, 40%, or 53.72%; the molybdenum concentrate contains 1.5-36.63% silica by mass, specifically 1.86%, 5%, 10%, 20%, 30%, or 35.63%.
[0020] In this invention, the acidic solution may include hydrochloric acid solution, sulfuric acid solution or nitric acid solution; the mass concentration of the acidic solution may be 25-35%, specifically 30%; the mass ratio of molybdenum concentrate to acidic solution may be 1:0.8-1.2, specifically 1:1.
[0021] In this invention, the acid leaching temperature can be 75~85℃, specifically 80℃; the acid leaching time can be 2.5~3.5h, specifically 3h; the acid leaching process can be accompanied by stirring, and this invention does not have a special limitation on the stirring speed, as long as it can be mixed evenly.
[0022] In this invention, the acid leaching process may further include: performing a first solid-liquid separation on the acid-leached system, washing the obtained solid with water, and then drying it to obtain crude molybdenum disulfide; the first solid-liquid separation may include vacuum filtration; the water used for the first washing may be deionized water, and the number of first washings may be 2 to 4 times, specifically 3 times; the temperature of the first drying may be 100 to 105°C, specifically 102°C; and the drying time may be 2 to 4 hours, specifically 3 hours.
[0023] This invention can remove acid-soluble impurities such as iron and calcium from molybdenum concentrate through acid leaching.
[0024] After obtaining crude molybdenum disulfide, the present invention soaks the crude molybdenum disulfide in an alkaline solution for alkaline leaching to obtain pure molybdenum disulfide. In the present invention, the alkaline solution may include sodium hydroxide solution and / or potassium hydroxide solution, specifically sodium hydroxide solution or potassium hydroxide solution; the mass concentration of the alkaline solution is 30-50%, specifically 33%, 40%, or 45%; the mass ratio of the alkaline solution to the crude molybdenum disulfide can be 1:0.1-10, specifically 1:0.35, 1:1, 1:1.8, 1:3, 1:3.4, 1:5, or 1:8.
[0025] In this invention, the alkaline leaching temperature can be 65~125℃, specifically 65℃, 70℃, 80℃, 90℃, 95℃, 110℃, or 120℃; the alkaline leaching time can be 5~10 hours, specifically 6 hours or 8 hours. In this invention, stirring can accompany the alkaline leaching process. This invention does not have a specific limitation on the stirring speed, as long as it ensures uniform mixing. In this invention, the process after alkaline leaching may further include: performing a second solid-liquid separation on the alkaline leaching system, and sequentially performing a second water wash and a second drying on the obtained solid; the second solid-liquid separation may include vacuum filtration; the water used for the second water wash may be deionized water, and the number of times the second water wash is performed may be 2 to 4 times, specifically 3 times; the temperature of the second drying may be 100 to 105°C, specifically 102°C; and the time of the second drying may be 2 to 4 hours, specifically 3 hours.
[0026] The impurity removal method provided by this invention has the following advantages over the method using hydrofluoric acid: 1) Economic advantages: Reduced raw material costs. The cost of sodium hydroxide is far lower than that of hydrofluoric acid, and it is easy to store and transport, requiring no special anti-corrosion equipment. The treatment cost of high-fluoride wastewater generated by traditional hydrofluoric acid processes is extremely high. The new process eliminates fluoride pollution at the source, significantly reducing wastewater treatment costs. The method provided by this invention can effectively remove silicon impurities from molybdenum disulfide, producing high-purity molybdenum disulfide products, which can significantly improve the market competitiveness and added value of the products. 2) Environmental advantages: The method provided by this invention does not use hydrofluoric acid, ensuring the health and safety of employees and greatly reducing the risk of safety production. At the same time, it avoids the generation of fluoride-containing wastewater and the emission of fluoride gas, reducing the generation of harmful substances at the source and minimizing the impact on the air, water, and soil environment. Since the reaction of dissolving silicon impurities with alkaline solution is relatively simple, the byproducts are mostly recyclable silicates, making wastewater treatment more environmentally friendly. Furthermore, reasonable waste recycling and reuse help reduce resource waste and promote circular economy.
[0027] Figure 1 This is a schematic diagram of the process for treating molybdenum concentrate using sodium hydroxide solution as an alkaline solution.
[0028] To further illustrate the present invention, the technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.
[0029] Example 1 100g of 30% hydrochloric acid solution was added to a 500mL three-necked reaction flask. Stirring was started, and 100g of molybdenum concentrate raw material (molybdenum content 53.72% and silica content 1.86%) was added. The temperature was slowly increased under stirring and maintained at 80℃ for acid leaching for 3 hours. After filtration, the solid obtained by filtration was washed three times with 100mL of deionized water and dried at 102℃ for 3 hours to obtain 96.5g of crude molybdenum disulfide with a molybdenum content of 56.42% and a silica content of 1.93%.
[0030] Add 90g of 40% sodium hydroxide solution to a 500mL three-necked reaction flask, start stirring, add 50g of crude molybdenum disulfide, and slowly heat while stirring. Maintain the temperature at 95℃ for alkali leaching for 5 hours, then filter. Wash the filtered solid three times with 100mL of deionized water, and dry at 102℃ for 3 hours to obtain 47.32g of pure molybdenum disulfide with a molybdenum content of 58.45% and a silicon dioxide content of 0.08%.
[0031] Example 2 Acid leaching was performed according to the method in Example 1 to obtain crude molybdenum disulfide.
[0032] 170 g of 33% sodium hydroxide solution was added to a 500 mL three-necked reaction flask. Stirring was started, and 50 g of crude molybdenum disulfide was added. The temperature was slowly increased under stirring and maintained at 65 °C for alkali leaching for 10 h. After filtration, the solid obtained by filtration was washed three times with 100 mL of deionized water and dried at 102 °C for 3 h to obtain 47.12 g of pure molybdenum disulfide with a molybdenum content of 58.55% and a silicon dioxide content of 0.08%.
[0033] Example 3 500g of 30% hydrochloric acid solution was added to a 2000mL three-necked reaction flask. Stirring was started, and 500g of molybdenum concentrate raw material (molybdenum content 19.04% and silica content 35.63%) was added. The temperature was slowly increased under stirring and maintained at 80℃ for acid leaching for 3 hours. After filtration, the solid obtained by filtration was washed three times with 150mL of deionized water and dried at 102℃ for 3 hours to obtain 424.32g of crude molybdenum disulfide with a molybdenum content of 21.32% and a silica content of 40.56%.
[0034] 300g of 50% sodium hydroxide solution was added to a 500mL three-necked reaction flask. Stirring was started, and 100g of crude molybdenum disulfide was added. The temperature was slowly increased under stirring and maintained at 95℃ for alkali leaching for 5 hours. After filtration, the solid obtained by filtration was washed three times with 150mL of deionized water and dried at 102℃ for 3 hours to obtain 36.23g of pure molybdenum disulfide with a molybdenum content of 56.72% and a silicon dioxide content of 0.08%.
[0035] Example 4 Acid leaching was performed according to the method in Example 3 to obtain crude molybdenum disulfide.
[0036] 500g of 40% sodium hydroxide solution was added to a 500mL three-necked reaction flask. Stirring was started, and 100g of crude molybdenum disulfide was added. The temperature was slowly increased under stirring and maintained at 125℃. After alkali leaching for 5 hours, the mixture was filtered. The solid obtained by filtration was washed three times with 150mL of deionized water and dried at 102℃ for 3 hours to obtain 34.78g of pure molybdenum disulfide with a molybdenum content of 57.59% and a silicon dioxide content of 0.07%.
[0037] Example 5 Acid leaching was performed according to the method in Example 3 to obtain crude molybdenum disulfide.
[0038] 500g of 50% sodium hydroxide solution was added to a 500mL three-necked reaction flask. Stirring was started, and 100g of crude molybdenum disulfide was added. The temperature was slowly increased under stirring and maintained at 65℃ for alkali leaching for 10h. After filtration, the solid obtained by filtration was washed three times with 150mL of deionized water and dried at 102℃ for 3h to obtain 34.67g of pure molybdenum disulfide with a molybdenum content of 58.98% and a silicon dioxide content of 0.08%.
[0039] Comparative Example 1 100g of 30% hydrochloric acid solution was added to a 500mL three-necked reaction flask. Stirring was started, and 100g of molybdenum concentrate raw material (molybdenum content 53.72% and silicon dioxide content 2.39%) was added. The temperature was slowly increased under stirring and maintained at 80℃ for acid leaching for 3 hours. After filtration, the solid obtained by filtration was washed three times with 100mL of deionized water and dried at 102℃ for 3 hours to obtain 96.5g of crude molybdenum disulfide with a molybdenum content of 56.42% and a silicon dioxide content of 1.93%.
[0040] 500g of 5% sodium hydroxide solution was added to a 500mL three-necked reaction flask. Stirring was started, and 50g of crude molybdenum disulfide was added. The temperature was slowly increased under stirring and maintained at 95℃ for alkali leaching for 5 hours. After filtration, the solid obtained by filtration was washed three times with 100mL of deionized water and dried at 102℃ for 3 hours to obtain 47.94g of pure molybdenum disulfide with a molybdenum content of 57.85% and a silicon dioxide content of 1.69%.
[0041] Comparative Example 2 Acid leaching was performed according to the method of Comparative Example 1 to obtain crude molybdenum disulfide.
[0042] 250g of 10% sodium hydroxide solution was added to a 500mL three-necked reaction flask. Stirring was started, and 50g of crude molybdenum disulfide was added. The temperature was slowly increased under stirring and maintained at 95℃ for alkali leaching for 5 hours. After filtration, the solid obtained by filtration was washed three times with 100mL of deionized water and dried at 102℃ for 3 hours to obtain 48.07g of pure molybdenum disulfide with a molybdenum content of 57.99% and a silicon dioxide content of 1.58%.
[0043] Comparative Example 3 Acid leaching was performed according to the method of Comparative Example 1 to obtain crude molybdenum disulfide.
[0044] 250g of 20% sodium hydroxide solution was added to a 500mL three-necked reaction flask. Stirring was started, and 50g of crude molybdenum disulfide was added. The temperature was slowly increased under stirring and maintained at 95℃ for alkali leaching for 5 hours. After filtration, the solid obtained by filtration was washed three times with 100mL of deionized water and dried at 102℃ for 3 hours to obtain 47.08g of pure molybdenum disulfide with a molybdenum content of 58.91% and a silicon dioxide content of 0.56%.
[0045] This invention utilizes ICP-AES to detect the molybdenum and silicon dioxide content in molybdenum concentrate and crude molybdenum disulfide. The molybdenum and silicon dioxide content in pure molybdenum disulfide was determined according to the detection method for molybdenum disulfide in GB / T 23271-2009, and the results are listed in Table 2.
[0046] Table 2. Purity and silica removal rate of the products in Examples 1-5 and Comparative Examples 1-3
[0047] As can be seen from the results in Table 2, the method provided by this invention can effectively remove silica from molybdenum concentrate and obtain high-purity molybdenum disulfide.
[0048] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. People can obtain other embodiments based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.
Claims
1. A method for removing impurities from molybdenum concentrate, characterized in that, Includes the following steps: Molybdenum concentrate is soaked in an acidic solution for acid leaching to obtain crude molybdenum disulfide. The crude molybdenum disulfide is soaked in an alkaline solution for alkaline leaching to obtain pure molybdenum disulfide; the mass concentration of the alkaline solution is 30-50%.
2. The method for removing impurities from molybdenum concentrate according to claim 1, characterized in that, The acidic solution includes hydrochloric acid solution, sulfuric acid solution, or nitric acid solution; the mass concentration of the acidic solution is 25-35%.
3. The method for removing impurities from molybdenum concentrate according to claim 2, characterized in that, The mass ratio of the molybdenum concentrate to the acidic solution is 1:0.8~1.
2.
4. The method for removing impurities from molybdenum concentrate according to any one of claims 1 to 3, characterized in that, The acid leaching temperature is 75~85℃, and the acid leaching time is 2.5~3.5h.
5. The method for removing impurities from molybdenum concentrate according to claim 4, characterized in that, The process after acid leaching further includes: performing a first solid-liquid separation on the acid-leached system, washing the obtained solid with water, and then drying it to obtain crude molybdenum disulfide.
6. The method for removing impurities from molybdenum concentrate according to claim 1, characterized in that, The mass ratio of the alkaline solution to crude molybdenum disulfide is 1:0.1~10.
7. The method for removing impurities from molybdenum concentrate according to claim 1 or 6, characterized in that, The alkaline solution includes sodium hydroxide solution and / or potassium hydroxide solution.
8. The method for removing impurities from molybdenum concentrate according to claim 7, characterized in that, The alkaline leaching temperature is 65~125℃, and the time is 5~10h.
9. The method for removing impurities from molybdenum concentrate according to claim 8, characterized in that, The process after alkaline leaching further includes: performing a second solid-liquid separation on the alkaline leaching system, and sequentially performing a second water washing and a second drying on the obtained solid.
10. The method for removing impurities from molybdenum concentrate according to claim 1, characterized in that, The molybdenum concentrate contains 19-56.4% molybdenum by mass and 1.5-36.63% silicon dioxide by mass.