Out-field reinforced molybdenum concentrate impurity removal method

Abstract

The invention discloses an external field reinforced molybdenum concentrate impurity removal method, and belongs to the technical field of molybdenum concentrate impurity removal. The method comprises the following steps: (1) microwave enhanced chloridizing roasting: uniformly mixing the molybdenum concentrate and calcium chloride, and carrying out microwave heating roasting in an inert atmosphere protection environment to obtain a roasted product; (2) ultrasonic enhanced acid leaching: adding the roasted material obtained in the step (1) into a hydrochloric acid solution, leaching under an ultrasonic condition, and then sequentially carrying out suction filtration, washing and drying to obtain an acid leached material; and (3) ultrasonic enhanced alkaline leaching is conducted, specifically, the acid leaching material obtained in the step (2) is added into a sodium hydroxide solution, leaching is conducted under the ultrasonic condition, then suction filtration, washing and drying are conducted in sequence, and iron and silicon removal of the molybdenum concentrate is completed. By means of the method, the iron and silicon removal effect of the molybdenum concentrate can be effectively improved, and the iron and silicon removal rate can reach 97% or above.

Description

Technical Field

[0001] The invention belongs to the technical field of molybdenum concentrate impurity removal, and relates to an external field enhanced molybdenum concentrate impurity removal method. Background Art

[0002] my country ranks first in the world in terms of molybdenum resource reserves, but molybdenum products are still mainly primary products of molybdenum oxide and ferromolybdenum. High value-added and high-tech molybdenum products still rely on imports, and structural contradictions are becoming increasingly prominent. High-purity molybdenum disulfide powder has unique and excellent mechanical, physical and chemical properties. It is known as the "king of solid lubrication" and is a high-end solid lubricant material for high-tech fields such as aerospace, military industry, nuclear industry and civil engineering. Therefore, efficient and clean preparation of high-purity MoS2 is a strong support for promoting the high-quality development of my country's molybdenum industry.

[0003] The natural mineral purification method uses molybdenum concentrate as raw material, and removes harmful impurities in the molybdenum concentrate through physical and chemical reactions to obtain molybdenum disulfide products. The products produced by this method retain the natural molybdenum disulfide crystal form, and the lubricant produced has good performance. The removal effect of impurities directly affects the quality of molybdenum disulfide products obtained by the natural mineral purification method, and the quality of molybdenum disulfide products affects the performance of lubricants. Therefore, it is of great significance to improve the removal effect of impurities and obtain higher quality molybdenum disulfide products.

[0004] Molybdenum concentrate mainly contains harmful impurities such as pyrite (Fe usually exists in the form of pyrite) and quartz (Si usually exists in the form of quartz, i.e. SiO2). At present, harmful impurities are usually leached out by acid leaching (acid leaching usually uses hydrochloric acid and hydrofluoric acid) to achieve the purpose of removing impurities. However, due to the high redox potential of pyrite (FeS2), it is difficult to react during the acid leaching process. During the roasting process, although part of the pyrite will be converted into pyrrhotite, its redox potential is reduced to a certain extent, and Fe can be removed by acid leaching, the conversion process is difficult, and pyrite cannot be completely converted, which affects the subsequent acid leaching and impurity removal. At the same time, quartz in molybdenum concentrate will be intercalated and coexist with MoS2 and FeS2, and wrap each other, which will hinder the contact of the reactants during the acid leaching process and affect the removal of impurities.

[0005] Therefore, it is necessary to provide a method for external field enhanced molybdenum concentrate impurity removal to improve the removal effect of iron and silicon impurities in molybdenum concentrate to obtain a molybdenum disulfide product with better quality. Summary of the invention

[0006] In order to solve the problems in the background technology, the present invention performs microwave-enhanced chlorination roasting on molybdenum concentrate. On the one hand, the quartz, MoS2, and FeS2 that are embedded, co-existing, and mutually wrapped in the molybdenum concentrate are dissociated to avoid the contact between the reactants during the leaching process, thereby improving the impurity removal effect; on the other hand, pyrite is converted into FeCl2, which reduces the difficulty of pyrite conversion, improves the thoroughness of pyrite conversion, reduces the reaction difficulty of the acid leaching process, and is beneficial to improving the iron leaching effect, thereby enhancing the impurity removal effect.

[0007] In order to achieve the above object, the present invention is implemented by the following technical solutions:

[0008] The method comprises the following steps:

[0009] (1) Microwave-enhanced chlorination roasting: After the molybdenum concentrate and calcium chloride are evenly mixed, microwave heating and roasting are carried out in an inert atmosphere to obtain a roasted product. The inert atmosphere can be nitrogen, argon, helium and other gases.

[0010] (2) Ultrasonic enhanced acid leaching: the roasted material obtained in step (1) is added to a hydrochloric acid solution, leached under ultrasonic conditions, and then filtered, washed, and dried in sequence to obtain an acid leached material.

[0011] (3) Ultrasonic enhanced alkaline leaching: the acid leaching material obtained in step (2) is added to a sodium hydroxide solution, leached under ultrasonic conditions, and then filtered, washed, and dried in sequence to complete the removal of iron and silicon from the molybdenum concentrate.

[0012] Preferably, in step (1), the mass ratio of molybdenum concentrate to calcium chloride is: molybdenum concentrate: CaCl2 = 3-10:1.

[0013] Preferably, in step (1), the calcination temperature is 700-900° C. and the holding time is 30-180 min.

[0014] Preferably, in step (2), the solid-liquid ratio of the calcined product to hydrochloric acid is 1 g:2-5 ml, the acid leaching time is 30-180 min, and the acid leaching temperature is 65-85°C.

[0015] Preferably, in step (2), the concentration of the hydrochloric acid solution is 5-15%.

[0016] Preferably, in step (3), the solid-liquid ratio of the acid leaching material to the sodium hydroxide solution is 1g:2-5ml, the leaching time is 30-180min, and the leaching temperature is 50-85°C.

[0017] Preferably, in step (3), the concentration of the sodium hydroxide solution is 5-15%.

[0018] Preferably, in steps (2) and (3), the ultrasonic frequency is 20-40 KHz and the power density is 50-300 W / L.

[0019] Preferably, the molybdenum concentrate is a molybdenum disulfide concentrate obtained after mining and selection of primary molybdenum ore, and the molybdenum disulfide content in the molybdenum concentrate is not less than 60%.

[0020] Beneficial effects of the present invention:

[0021] 1. The present invention roasts the molybdenum concentrate with calcium chloride so that FeS2 and CaCl2 in the molybdenum concentrate react to generate FeCl2, thereby reducing the difficulty of pyrite conversion and more thoroughly converting pyrite into FeCl2 that is easy to acid-leach, which is beneficial to improving the subsequent acid-leaching impurity removal effect. In addition, part of FeCl2 escapes in the form of steam, that is, part of the impurities are removed in the roasting stage, which is beneficial to reducing the subsequent acid-leaching impurity removal pressure and reducing the amount of acid used in the acid-leaching process. On the one hand, acid consumption is saved, which is helpful to reduce the impurity removal cost. On the other hand, the amount of waste acid liquid generated is reduced, and the difficulty of waste acid liquid treatment is reduced. At the same time, the byproduct CaS is easily soluble in acid and no new impurities are introduced.

[0022] 2. The present invention performs microwave-enhanced chlorination roasting on a mixture of molybdenum concentrate and calcium chloride, so as to dissociate the quartz, MoS2, and FeS2 that are interwoven and mutually wrapped in the molybdenum concentrate, reduce or eliminate the contact barrier of the reactants, and further enhance the impurity removal effect.

[0023] 3. Since hydrofluoric acid can quickly penetrate the skin, combine with calcium and magnesium ions to form insoluble calcium fluoride, etc., reduce the calcium and magnesium levels in the blood, cause heart problems, and even death in severe cases; and hydrogen fluoride easily forms gas escape, and people inhale the gas, causing damage; at the same time, hydrofluoric acid is not easy to degrade in the environment, causing long-term pollution to water bodies and soil. The present invention uses sodium hydroxide solution for alkaline leaching to replace hydrofluoric acid acid leaching. Although sodium hydroxide is also corrosive, even if it causes harm to the human body, it is limited to the surface and can be handled by simple emergency measures such as flushing. At the same time, sodium hydroxide is not easy to produce gas escape and is also relatively easy to degrade in the environment. Therefore, the present invention can reduce the difficulty of leachate treatment and avoid the high risk of using hydrofluoric acid.

[0024] 4. The present invention introduces ultrasonic treatment during acid leaching and alkali leaching, utilizes the mechanical effect and cavitation effect of ultrasound, strengthens the leaching kinetic conditions, further activates the molybdenum concentrate, and is conducive to more thorough leaching of impurities.

[0025] 5. The present invention can shorten the roasting time, has a highly efficient cleaning and deep impurity removal effect, a high impurity removal rate, and is environmentally friendly. DETAILED DESCRIPTION

[0026] The present invention is further described in detail below in conjunction with specific embodiments, but the protection scope of the present invention is not limited to the described contents.

[0027] In the examples and comparative examples of the present invention, chemical reagents not otherwise specified were all commercially available analytically pure reagents for the experiments.

[0028] Example 1

[0029] This embodiment removes impurities in the molybdenum concentrate by the following method:

[0030] (1) Microwave enhanced roasting: Molybdenum concentrate and calcium chloride were mixed in a mass ratio of 10:1, placed in a microwave heating device and filled with nitrogen, and roasted at 700°C for 30 minutes. After cooling, the roasted material was obtained.

[0031] (2) Ultrasonic enhanced acid leaching: The roasted material obtained in step (1) was added to a 5% hydrochloric acid solution at a solid-liquid ratio of 1 g:2 ml, and leached for 30 min at a temperature of 65°C, an ultrasonic frequency of 25 kHz, and a power density of 50 W / L. During the leaching process, the liquid was continuously stirred at a stirring speed of 300 rpm. After the leaching was completed, the material was washed, filtered, and dried to obtain an acid leached material.

[0032] (3) Ultrasonic enhanced alkaline leaching: The acid leached material obtained in step (2) was added to a 5% sodium hydroxide solution at a solid-liquid ratio of 1 g:2 ml, and leached for 30 min at a temperature of 50°C, an ultrasonic frequency of 20 kHz, and a power density of 50 W / L. During the leaching process, the liquid was continuously stirred at a stirring speed of 300 rpm. After the leaching was completed, the material was washed, filtered, and dried to complete the removal of impurities.

[0033] The final product of this embodiment was tested, and it was found that the mass percentage of iron in the product was 0.382%, and the iron removal rate was about 90.80%; the mass percentage of silicon in the product was 0.367%, and the silicon removal rate was about 90.44%.

[0034] Embodiment 2:

[0035] This embodiment removes impurities in the molybdenum concentrate by the following method:

[0036] (1) Microwave enhanced roasting: Molybdenum concentrate and calcium chloride were mixed in a mass ratio of 8:1, placed in a microwave heating device and filled with nitrogen, and roasted at 800°C for 60 minutes. After cooling, the roasted material was obtained.

[0037] (2) Ultrasonic enhanced acid leaching: The roasted material obtained in step (1) was added to a 10% hydrochloric acid solution at a solid-liquid ratio of 1 g:3 ml, and leached for 60 min at a temperature of 70°C, an ultrasonic frequency of 25 kHz, and a power density of 150 W / L. During the leaching process, the liquid was continuously stirred at a stirring speed of 300 rpm. After the leaching was completed, the material was washed, filtered, and dried to obtain an acid leached material.

[0038] (3) Ultrasonic enhanced alkaline leaching: The acid leached material obtained in step (2) was added to a 10% sodium hydroxide solution at a solid-liquid ratio of 1 g:3 ml, and leached for 60 min at a temperature of 70°C, an ultrasonic frequency of 25 kHz, and a power density of 150 W / L. During the leaching process, the liquid was continuously stirred at a stirring speed of 300 rpm. After the leaching was completed, the material was washed, filtered, and dried to complete the removal of impurities.

[0039] The final product of this embodiment was tested, and it was found that the mass percentage of iron in the product was 0.269%, and the iron removal rate was about 93.52%; the mass percentage of silicon in the product was 0.28%, and the silicon removal rate was about 92.71%.

[0040] Embodiment 3:

[0041] This embodiment removes impurities in the molybdenum concentrate by the following method:

[0042] (1) Microwave enhanced roasting: The molybdenum concentrate and calcium chloride were mixed in a mass ratio of 5:1, placed in a microwave heating device and filled with nitrogen, and roasted at 850°C for 120 minutes. After cooling, the roasted material was obtained.

[0043] (2) Ultrasonic enhanced acid leaching: The roasted material obtained in step (1) was added to a 10% hydrochloric acid solution at a solid-liquid ratio of 1 g:4 ml, and leached for 120 min at a temperature of 80°C, an ultrasonic frequency of 25 kHz, and a power density of 200 W / L. During the leaching process, the liquid was continuously stirred at a stirring speed of 300 rpm. After the leaching was completed, the material was washed, filtered, and dried to obtain an acid leached material.

[0044] (3) Ultrasonic enhanced alkaline leaching: The acid leached material obtained in step (2) was added to a 10% sodium hydroxide solution at a solid-liquid ratio of 1 g:4 ml, and leached for 120 min at a temperature of 80°C, an ultrasonic frequency of 25 kHz, and a power density of 200 W / L. During the leaching process, the liquid was continuously stirred at a stirring speed of 300 rpm. After the leaching was completed, the liquid was washed, filtered, and dried to complete the removal of impurities.

[0045] The final product of this embodiment was tested, and the mass percentage of iron in the product was measured to be 0.162%, and the iron removal rate was about 96.10%; the mass percentage of silicon in the product was 0.142%, and the silicon removal rate was about 96.30%.

[0046] Embodiment 4:

[0047] This embodiment removes impurities in the molybdenum concentrate by the following method:

[0048] (1) Microwave enhanced roasting: The molybdenum concentrate and calcium chloride were mixed in a mass ratio of 3:1, placed in a microwave heating device and filled with nitrogen, and roasted at 900°C for 180 minutes. After cooling, the roasted material was obtained.

[0049] (2) Ultrasonic enhanced acid leaching: The roasted material obtained in step (1) was added to a 15% hydrochloric acid solution at a solid-liquid ratio of 1 g:5 ml, and leached for 180 min at a temperature of 85° C., an ultrasonic frequency of 40 kHz, and a power density of 300 W / L. During the leaching process, the liquid was continuously stirred at a stirring speed of 300 rpm. After the leaching was completed, the material was washed, filtered, and dried to obtain an acid leached material.

[0050] (3) Ultrasonic enhanced alkaline leaching: The acid leached material obtained in step (2) was added to a 15% sodium hydroxide solution at a solid-liquid ratio of 1 g:5 ml, and leached for 180 min at a temperature of 85°C, an ultrasonic frequency of 40 kHz, and a power density of 300 W / L. During the leaching process, the liquid was continuously stirred at a stirring speed of 300 rpm. After the leaching was completed, the liquid was washed, filtered, and dried to complete the removal of impurities.

[0051] The final product of this embodiment was tested, and the mass percentage of iron in the product was measured to be 0.108%, and the iron removal rate was about 97.40%; the mass percentage of silicon in the product was 0.098%, and the silicon removal rate was about 97.45%.

[0052] Comparative Example 1:

[0053] This comparative example removes impurities in molybdenum concentrate by the following method:

[0054] This comparative example adopts the same method as Example 1 to remove impurities in the molybdenum concentrate, except that: in this comparative example, CaCl2 is not introduced during the microwave roasting stage, and the molybdenum concentrate is directly roasted by microwave.

[0055] The final product of this comparative example was tested, and it was found that the mass percentage of iron in the product was 0.859%, and the iron removal rate was about 79.30%; the mass percentage of silicon in the product was 0.752%, and the silicon removal rate was about 80.42%.

[0056] Comparative Example 2:

[0057] This comparative example adopts the same method as Example 1 to remove impurities in the molybdenum concentrate, except that in this comparative example, ultrasonic treatment is not introduced during the acid leaching and alkali leaching processes.

[0058] The final product of this comparative example was tested, and it was found that the mass percentage of iron in the product was 0.526%, and the iron removal rate was about 87.33%; the mass percentage of silicon in the product was 0.481%, and the silicon removal rate was about 87.47%.

[0059] By comparing Example 1 with Comparative Example 1, it can be seen that the impurity removal effect of Comparative Example 1 is significantly reduced. The reason is that the pyrite conversion efficiency in the molybdenum concentrate is low and has not been completely converted, and the residual pyrite cannot be effectively leached. In Example 1, calcium chloride is added for roasting, and the pyrite conversion is more thorough, reducing the amount of residual pyrite, so that more pyrite is converted and leached in subsequent acid leaching, and part of the generated ferric chloride will escape in the form of steam, which can accelerate the reaction speed and improve the conversion efficiency.

[0060] By comparing Example 1 with Comparative Example 2, it can be seen that the impurity removal effect of Comparative Example 2 is significantly reduced. The reason is that due to the lack of the activation effect of ultrasound on the leaching process, the mechanical effect and cavitation effect of ultrasound can improve the leaching process dynamics and enhance the leaching efficiency.

[0061] By comparing Comparative Example 1 and Comparative Example 2, it can be seen that the impurity removal effect in Comparative Example 2 is better, which fully illustrates that the roasting conversion of pyrite is more difficult.

[0062] In summary, by removing impurities from molybdenum concentrate using the method of the present invention, the impurity removal effect can be effectively improved to obtain a higher quality molybdenum disulfide product.

[0063] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made in form and details without departing from the scope defined by the claims of the present invention.

Claims

1. A method for removing impurities from molybdenum concentrate by external field strengthening, characterized in that: The method comprises the following steps: (1) Microwave-enhanced chlorination roasting: After the molybdenum concentrate and calcium chloride are uniformly mixed, microwave heating and roasting are performed in an inert atmosphere protection environment to obtain a roasted product; (2) Ultrasonic enhanced acid leaching: adding the roasted material obtained in step (1) into a hydrochloric acid solution, leaching under ultrasonic conditions, and then filtering, washing, and drying in sequence to obtain an acid leached material; (3) Ultrasonic enhanced alkaline leaching: the acid leaching material obtained in step (2) is added to a sodium hydroxide solution, leached under ultrasonic conditions, and then filtered, washed, and dried in sequence to complete the removal of iron and silicon from the molybdenum concentrate.

2. The method according to claim 1, characterized in that: In the step (1), the mass ratio of molybdenum concentrate to calcium chloride is: molybdenum concentrate: CaCl2 = 3-10:

1.

3. The method according to claim 1, characterized in that: In the step (1), the calcination temperature is 700-900° C. and the insulation time is 30-180 min.

4. The method according to claim 1, characterized in that: In the step (2), the solid-liquid ratio of the calcined product to the hydrochloric acid is 1 g:2-5 ml, the acid leaching time is 30-180 min, and the acid leaching temperature is 65-85°C.

5. The method according to claim 1 or 4, characterized in that: In the step (2), the concentration of the hydrochloric acid solution is 5-15%.

6. The method according to claim 1, characterized in that: In the step (3), the solid-liquid ratio of the acid leaching material to the sodium hydroxide solution is 1g:2-5ml, the leaching time is 30-180min, and the leaching temperature is 50-85°C.

7. The method according to claim 1 or 6, characterized in that: In the step (3), the concentration of the sodium hydroxide solution is 5-15%.

8. The method according to claim 1, characterized in that: In the steps (2) and (3), the ultrasonic frequency is 20-40 KHz and the power density is 50-300 W / L.

9. The method according to any one of claims 1, 2, 3, 4, 6, and 8, characterized in that: The molybdenum concentrate is a molybdenum disulfide concentrate obtained after mining and selection of primary molybdenum ore, and the content of molybdenum disulfide in the molybdenum concentrate is not less than 60%.