Process method for preparing molybdenum powder through reduction of high heteromolybdic acid

Abstract

The invention discloses a technological method for preparing molybdenum powder through reduction of high heteromolybdic acid, and belongs to the technical field of technological preparation methods of molybdenum powder. The process method comprises the steps that a raw material high heteromolybdic acid is subjected to first hydrogen reduction in a four-tube furnace, an obtained reduction product is subjected to second hydrogen reduction, then heating alkali washing and heating acid washing are sequentially conducted, and high-purity molybdenum powder is obtained. Molybdenum acid can be used for replacing traditional ammonium molybdate to serve as a raw material for producing molybdenum powder, the production technological process is remarkably shortened, and the production cost is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of a process for preparing molybdenum powder, and in particular to a process for preparing molybdenum powder by reducing molybdic acid with a high impurity content. Background Art

[0002] Molybdenum is one of the important alloying elements added to stainless steel. It can effectively improve the corrosion resistance and strength of stainless steel, and improve its antibacterial and anti-corrosion capabilities. Therefore, in high-end stainless steel products, especially stainless steel products with high requirements for corrosion resistance and wear resistance, higher levels of molybdenum are usually added. For example, Mo stainless steel, which is widely used in marine engineering, sewage treatment, chemical industry and other fields, has a molybdenum content of 3-4%. On the other hand, low-alloy stainless steel with appropriate addition of molybdenum can also be used to prepare stainless steel materials with high strength, high toughness and good wear resistance, and used in the automotive industry, aerospace and other fields.

[0003] At present, the industrial process for preparing molybdenum powder generally uses ammonium molybdate as raw material and obtains molybdenum powder through hydrogen reduction method, but this preparation process will result in high production cost and low profit. Therefore, in order to obtain higher profit of molybdenum powder production, it is an urgent technical problem to find a lower cost process method. Summary of the invention

[0004] In view of the defects of the prior art, the purpose of the present invention is to provide a new process for preparing molybdenum powder by reducing high-impurity molybdenum acid, which can use molybdenum acid with a high impurity content as a raw material to obtain high-purity molybdenum powder, thereby significantly reducing the production cost of molybdenum powder preparation.

[0005] The technical solution of the present invention is as follows: The process for preparing molybdenum powder by reducing high-mixed molybdenum acid comprises: (1) subjecting the raw material high-isopropyl molybdic acid to a first hydrogen reduction in a four-tube furnace at a reduction temperature of 400-700° C. to obtain a first reduction product; (2) subjecting the first reduction product to a second hydrogen reduction at a reduction temperature of 800 to 1200° C. to obtain a second reduction product; (3) heating and alkali-washing the second reduction product with an alkali solution, followed by filtering and drying to obtain an alkali-washed product; (4) heating and pickling the alkali-washed product with an acid solution, followed by filtering and drying to obtain an acid-washed product, i.e., molybdenum powder; Wherein, the high heteromolybdic acid comprises Ca content greater than 5000 ppm, Si content greater than 5000 ppm, V content greater than 5000 ppm and W content greater than 5000 ppm.

[0006] According to some preferred embodiments of the present invention, it also includes: (5) Screening the pickling product to obtain finished molybdenum powder.

[0007] According to some preferred embodiments of the present invention, in the first hydrogen reduction, the flow rate of hydrogen is 4 to 12 m 3 / h, the loading amount of the raw material high heteromolybdic acid is 2.0-5.0 kg / boat, and the pushing speed is 10-20 min / track.

[0008] According to some preferred embodiments of the present invention, in the second hydrogen reduction, the flow rate of hydrogen is 15-30m 3 / h, the loading amount of the first reduction product is 1.0-3.0 kg / boat, and the pushing speed is 20-30 min / track.

[0009] According to some preferred embodiments of the present invention, the alkali solution is an aqueous solution of sodium carbonate, and its concentration is 0.3-0.6 wt %.

[0010] According to some preferred embodiments of the present invention, the mass ratio of the second reduction product to the alkali solution is 1:(4-10).

[0011] According to some preferred embodiments of the present invention, the heating temperature of the alkali washing is 60-100° C., and the heating time is 20-40 min.

[0012] According to some preferred embodiments of the present invention, the acid solution is selected from one or more of sulfuric acid, nitric acid and hydrochloric acid, and the concentration of the acid solution is 20-40wt%.

[0013] According to some preferred embodiments of the present invention, the mass ratio of the alkali washing product to the acid solution is 1:(4-10).

[0014] According to some preferred embodiments of the present invention, the heating temperature of the heated pickling is 40-70° C., and the heating time is 20-40 min.

[0015] The beneficial effects of the present invention include: The process for preparing molybdenum powder by reducing high-isomolybdic acid provided by the present invention adopts molybdic acid instead of traditional ammonium molybdate as the raw material for producing molybdenum powder, which significantly shortens the production process and reduces the production cost. In addition, the entire process does not involve ammonia, does not generate ammonia gas, and has no pollutant emissions.

[0016] The process method of the present invention first utilizes high-temperature reduction to remove volatile substances in the raw materials, then utilizes molybdenum powder alkali washing to remove impurities such as Ca and Si brought by the high-impurity raw materials, and then utilizes molybdenum powder acid washing to remove impurities such as V and W brought by the high-impurity raw materials. The purity of the molybdenum powder finally prepared can reach more than 99%, which meets the demand for molybdenum powder used as a high-temperature alloy additive. DETAILED DESCRIPTION

[0017] The technical scheme of the present invention is clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other implementation methods obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0018] Example 1 Molybdenum powder is prepared by the following process steps: (1) 50 kg of high-isopropyl molybdenum acid was reduced with hydrogen in a four-tube furnace to obtain molybdenum dioxide, wherein the temperature of hydrogen reduction was 500 °C and the flow rate was 8 m 3 / h, the loading amount of high-iso molybdic acid is 2.0kg / boat, and the pushing speed is 11min / lane; the high-iso molybdic acid used contains Ca: 0.5680%, Si: 0.4992%, V: 0.6321%, W: 0.5910%; (2) The obtained molybdenum dioxide is reduced with hydrogen in a high-temperature reduction furnace to obtain reduced molybdenum powder, wherein the temperature of hydrogen reduction is 950°C and the flow rate is 20m 3 / h, the molybdenum dioxide loading is 1.5kg / boat, and the pushing speed is 20min / track; (3) adding 50 ml of a 0.43 wt% Na2CO3 aqueous solution to 10 g of reduced molybdenum powder for heating and alkali washing at a temperature of 70°C for 30 min. After washing, filtering and drying were performed to obtain alkali-washed molybdenum powder; (4) adding 50 ml of a 20 wt % sulfuric acid solution to the molybdenum powder after alkali washing for heating and pickling at a temperature of 40° C. for 30 min. After washing, filtering and drying are performed to obtain the molybdenum powder after pickling; (5) The molybdenum powder after pickling is sieved to obtain finished molybdenum powder.

[0019] Example 2 Molybdenum powder is prepared by the following process steps: (1) 50 kg of high-mixed molybdenum acid was reduced with hydrogen in a four-tube furnace to obtain molybdenum dioxide, wherein the temperature of hydrogen reduction was 550 ° C and the flow rate was 8 m 3 / h, the loading amount of high-iso molybdic acid is 2.0kg / boat, and the pushing speed is 11min / track; the high-iso molybdic acid used contains Ca: 0.6180%, Si: 0.5795%, V: 0.6399%, W: 0.6210%; (2) The obtained molybdenum dioxide is reduced with hydrogen in a high-temperature reduction furnace to obtain reduced molybdenum powder, wherein the temperature of hydrogen reduction is 1000°C and the flow rate is 20m 3 / h, the molybdenum dioxide loading is 1.5kg / boat, and the pushing speed is 20min / track; (3) adding 60 ml of a 0.43 wt% Na2CO3 aqueous solution to 10 g of reduced molybdenum powder for heating and alkali washing at 80 °C for 25 min, filtering and drying after washing to obtain alkali-washed molybdenum powder; (4) adding 60 ml of a 20 wt% sulfuric acid solution to the molybdenum powder after alkali washing for heating and pickling at a temperature of 50° C. for 25 min. After washing, filtering and drying are performed to obtain the molybdenum powder after pickling; (5) The molybdenum powder after pickling is sieved to obtain finished molybdenum powder.

[0020] Example 3 Molybdenum powder is prepared by the following process steps: (1) 50 kg of high-mixed molybdenum acid was reduced with hydrogen in a four-tube furnace to obtain molybdenum dioxide, wherein the temperature of hydrogen reduction was 600 °C and the flow rate was 8 m 3 / h, the loading amount of high-mixed molybdenum acid is 2.0kg / boat, and the pushing speed is 10min / track; the high-mixed molybdenum acid used contains Ca: 0.7590%, Si: 0.7213%, V: 0.5312%, W: 0.8100%; (2) The obtained molybdenum dioxide is reduced with hydrogen in a high-temperature reduction furnace to obtain reduced molybdenum powder, wherein the temperature of hydrogen reduction is 1050°C and the flow rate is 20m 3 / h, the molybdenum dioxide loading is 1.5kg / boat, and the pushing speed is 18min / track; (3) adding 50 ml of a 0.43 wt% Na2CO3 aqueous solution to 10 g of reduced molybdenum powder for heating and alkali washing at 80 °C for 25 min, filtering and drying after washing to obtain alkali-washed molybdenum powder; (4) adding 60 ml of a 30 wt % sulfuric acid solution to the molybdenum powder after alkali washing for heating and pickling at a temperature of 50° C. for 25 min. After washing, filtering and drying are performed to obtain the molybdenum powder after pickling; (5) The molybdenum powder after pickling is sieved to obtain finished molybdenum powder.

[0021] The above embodiments of the present invention can significantly reduce the production cost of molybdenum powder, and the chemical composition analysis of the finished molybdenum powder obtained in the above embodiments 1-3 shows that the purity of the molybdenum powder is between 99.4% and 99.7%, wherein Ca<0.030%, Si<0.030%, V<0.040%, and W<0.050%.

[0022] The above embodiments are preferred implementations of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. It should be pointed out that for ordinary technicians in this technical field, improvements and modifications without departing from the principle of the present invention should also be regarded as the protection scope of the present invention.

Claims

1. A process for preparing molybdenum powder by reducing high-mixed molybdenum acid, characterized in that: It includes: (1) subjecting the raw material high-isopropyl molybdic acid to a first hydrogen reduction in a four-tube furnace at a reduction temperature of 400-700° C. to obtain a first reduction product; (2) subjecting the first reduction product to a second hydrogen reduction at a reduction temperature of 800 to 1200° C. to obtain a second reduction product; (3) heating and alkali-washing the second reduction product with an alkali solution, followed by filtering and drying to obtain an alkali-washed product; (4) heating and pickling the alkali-washed product with an acid solution, followed by filtering and drying to obtain an acid-washed product, i.e., molybdenum powder; Wherein, the high heteromolybdic acid comprises Ca content greater than 5000 ppm, Si content greater than 5000 ppm, V content greater than 5000 ppm and W content greater than 5000 ppm.

2. The process according to claim 1, characterized in that: It also includes: (5) Screening the pickling product to obtain finished molybdenum powder.

3. The process according to claim 1, characterized in that: In the first hydrogen reduction, the flow rate of hydrogen is 4 to 12 m 3 / h, the loading amount of the raw material high heteromolybdic acid is 2.0-5.0 kg / boat, and the pushing speed is 10-20 min / track.

4. The process according to claim 1, characterized in that: In the second hydrogen reduction, the flow rate of hydrogen is 15-30m 3 / h, the loading amount of the first reduction product is 1.0-3.0 kg / boat, and the pushing speed is 20-30 min / track.

5. The process according to claim 1, characterized in that: The alkali solution is an aqueous solution of sodium carbonate, and its concentration is 0.3-0.6 wt %.

6. The process according to claim 1, characterized in that: The mass ratio of the second reduction product to the alkali solution is 1:(4-10).

7. The process according to claim 1, characterized in that: The heating temperature of the heated alkali washing is 60-100° C., and the heating time is 20-40 minutes.

8. The process according to claim 1, characterized in that: The acid solution is selected from one or more of sulfuric acid, nitric acid and hydrochloric acid, and the concentration of the acid solution is 20-40wt%.

9. The process according to claim 1, characterized in that: The mass ratio of the alkaline washing product to the acid solution is 1:(4-10).

10. The process according to claim 1, characterized in that: The heating temperature of the heated pickling is 40-70° C., and the heating time is 20-40 minutes.