High-purity tungsten refining method based on plasma beam furnace

Abstract

The invention discloses a high-purity tungsten refining method based on a plasma beam furnace, which is characterized by comprising the following steps of: 1, pre-removing pollutants on the surface of metal tungsten waste, pressing to obtain a tungsten raw material, filling the tungsten raw material into a crucible, and vacuumizing; secondly, the tungsten raw material treated in the first step is added into a plasma beam smelting furnace under the inert atmosphere environment, the temperature is gradually increased till alloy is melted, then heat preservation is conducted, high-temperature refining is conducted through plasma beams, and the tungsten raw material is in a local melting or evaporation state; 3, after volatilizing according to the boiling points of the impurities from low to high, collecting by adopting an impurity cooling and collecting device; and fourthly, the refined and purified tungsten material is cooled, machined or subjected to heat treatment, and a high-purity tungsten product is obtained. The method provided by the invention overcomes the limitation of the traditional method in the aspect of removing gaseous or high-volatility impurities, and can effectively reduce the content of oxygen, silicon and iron impurities in tungsten and improve the product quality.

Description

Technical Field

[0001] The present invention relates to the technical field of metal tungsten recovery and smelting, and particularly relates to a high-purity tungsten refining method based on a plasma beam furnace. Background Art

[0002] Due to its high melting point, high hardness, excellent high-temperature performance and corrosion resistance, tungsten is widely used in high-end fields such as aerospace, nuclear industry, and electronics industry. For example, in the aerospace field, high-purity tungsten is used to manufacture high-temperature resistant nozzles, engine components and spacecraft thermal protection systems; in the nuclear industry, due to its high density and good radiation resistance, tungsten is used as nuclear reactor shielding materials and radioactive isotope containers; in the electronics industry, tungsten is used to manufacture high-performance electrodes, X-ray tubes, sputtering targets in semiconductor chip manufacturing processes, etc.

[0003] In addition, tungsten is also widely used in high-end tool manufacturing, medical equipment and military fields, such as armor-piercing bullet cores, ultra-hard tools and biomedical implant materials, etc. However, natural tungsten ore or industrially purified tungsten materials usually contain impurity elements (such as oxygen, sulfur, silicon, iron, etc.), and these impurities will affect the performance of tungsten materials. At the same time, due to its extremely high melting point, the preparation cost of tungsten is relatively high.

[0004] Therefore, it is of great significance to develop an efficient waste recycling and refining technology for high-purity tungsten to remove impurities in tungsten, improve its purity to above 6N (99.9999%), and enable its low-cost application in high-end fields.

[0005] Existing tungsten refining methods mainly include zone melting method, hydrogen reduction method, arc melting method, etc. However, these methods have limitations in removing gaseous or highly volatile impurities, and the process flow is complex and the cost is relatively high. Therefore, there is an urgent need for an efficient and low-pollution refining technology.

[0006] As an advanced refining technology, the plasma beam furnace has broad application prospects in the field of metal refining due to its high temperature, high energy density and pollution-free characteristics.

[0007] The present invention proposes a high-purity tungsten refining method based on a plasma beam furnace to recycle tungsten waste metal and improve its purity for effective resource recovery and utilization. Summary of the Invention

[0008] In order to overcome the above defects of the prior art, the purpose of the present invention is to provide a high-purity tungsten refining method based on a plasma beam furnace.

[0009] A high-purity tungsten refining method based on a plasma beam furnace includes the following steps:

[0010] First step, after pre-removing surface contaminants from metal tungsten waste, pressing to obtain tungsten raw materials, loading them into a crucible, and then performing vacuum treatment;

[0011] In the second step, the tungsten raw material after the first-step treatment is added into a plasma beam melting furnace in an inert atmosphere environment, and the temperature is gradually increased until the alloy melts and then held for heat preservation. High-temperature refining is carried out using a plasma beam to make it reach a state of partial melting or evaporation;

[0012] In the third step, after the impurities are volatilized from low to high boiling points, an impurity cooling and collection device is used for collection;

[0013] In the fourth step, the refined and purified tungsten material is cooled, machined mechanically or heat-treated to obtain a high-purity tungsten product.

[0014] In a preferred embodiment of the present invention, the pre-removal is pickling and then drying treatment.

[0015] In a preferred embodiment of the present invention, the inert atmosphere is a mixed gas of hydrogen and helium or a mixed gas of hydrogen and argon,

[0016] The volume ratio of the hydrogen in the mixed gas is 0-5%.

[0017] In a preferred embodiment of the present invention, the refining temperature is 4000°C - 5000°C, and the refining time is 15 - 30 min.

[0018] In a preferred embodiment of the present invention, the heat preservation in the plasma beam melting furnace is to control the melting temperature of the plasma beam melting furnace to gradually increase to the melting of the alloy after reaching 1400°C and then hold for heat preservation.

[0019] In a preferred embodiment of the present invention, the low-boiling-point impurities are Fe, Si, Al, and O impurities.

[0020] In a preferred embodiment of the present invention, the metal tungsten waste is metal tungsten powder waste, metal tungsten chip waste, metal tungsten block waste, and irregular-shaped waste impurities of metal tungsten.

[0021] In a preferred embodiment of the present invention, the cooling is cooling treatment using a crystallizer.

[0022] In a preferred embodiment of the present invention, the treatment of evacuating after loading into the crucible is to load into a water-cooled copper crucible and evacuate in a vacuum chamber.

[0023] The beneficial effects of the present invention are as follows:

[0024] The present invention provides a method for purifying metal tungsten based on a plasma beam. This method uses a plasma beam to conduct directional heating and evaporation purification of metal tungsten, and utilizes the volatility difference between impurity elements and tungsten under high-temperature conditions to achieve efficient removal of impurities and obtain high-purity tungsten.

[0025] The method of the present invention overcomes the limitations of traditional methods in removing gaseous or highly volatile impurities, can effectively reduce the contents of oxygen, silicon, and iron impurities in tungsten, and improve the product quality. Specific Embodiments

[0026] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below through embodiments. However, it should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the scope of the present invention. In addition, in the following structures, descriptions of well-known structures and technologies are omitted to avoid unnecessarily confusing the concepts of the present invention.

[0027] Example 1:

[0028] In this example, metal tungsten powder materials and metal tungsten cutting materials are used as tungsten waste materials for melting and refining. The refining technology includes the following steps:

[0029] Step 1. Pickle and dry the collected metal tungsten powder materials and metal tungsten cutting materials;

[0030] Step 2. Press the pickled and dried metal tungsten powder materials and metal tungsten cutting materials into block materials, load them into a water-cooled copper crucible, evacuate in a vacuum chamber, and then perform smelting in a plasma beam melting furnace;

[0031] Step 3. Heat the plasma gun, and introduce a mixed gas of hydrogen and argon into the plasma beam furnace. In the mixed gas of hydrogen and argon, the volume ratio of hydrogen in the mixed gas is 3%.

[0032] Step 4. Control the smelting temperature of the plasma beam melting furnace at 1400 °C, raise the temperature until the alloy melts, keep the temperature for 10 min, and then continuously raise the temperature to 4200 °C for refining. The refining time is 20 min. When the melt surface is completely clarified, remove the slag on the alloy surface completely.

[0033] Step 5: Cool the tungsten melt through a crystallizer to obtain a high-purity tungsten ingot, and the purity level of the high-purity tungsten ingot reaches the 6N (99.9999%) level.

[0034] Table 1 Changes in the contents of oxygen, iron, and silicon in tungsten waste materials before refining and high-purity tungsten ingots after refining

[0035] Oxygen content Silicon content Fe content Tungsten waste 50 ppm 10 ppm 8 ppm Refined tungsten ingot 5 ppm 2 ppm 1 ppm

[0036] Example 2:

[0037] In this example, metal tungsten block materials are used as tungsten waste materials for melting and refining. The refining technology includes the following steps:

[0038] Step 1. Pickle and dry the collected tungsten metal ingots.

[0039] Step 2. Load the pickled and dried tungsten ingots into a water-cooled copper crucible, evacuate the vacuum chamber, and then melt them in a plasma beam melting furnace.

[0040] Step 3. Heat the plasma gun and introduce a mixed gas of hydrogen and helium into the plasma beam furnace. The volume ratio of hydrogen in the mixed gas is 5%.

[0041] Step 4. Control the melting temperature of the plasma beam melting furnace at 1400°C. Raise the temperature until the alloy melts. After holding for 10 minutes, continue to raise the temperature to 4200°C for refining. The refining time is 30 minutes. When the molten metal surface is completely clear and the scum on the alloy surface is removed completely.

[0042] Step 5: Cool the tungsten melt through a crystallizer to obtain a high-purity tungsten ingot. The purity level of the high-purity tungsten ingot reaches 6N (99.9999%).

[0043] Table 2 Changes in oxygen, iron, and silicon contents in tungsten waste before refining and high-purity tungsten ingots after refining

[0044] Oxygen content Silicon content Fe content Tungsten waste 40 ppm 12 ppm 8 ppm Refined tungsten ingot 0.3 ppm 0.2 ppm 0.1

[0045] The above shows and describes the basic principles, main features, and advantages of the invention.

[0046] By starting the plasma beam generator and adjusting the energy density, the present invention melts tungsten. At the same time, it adjusts the components and ratios in the inert gas to fully react with oxygen impurities, so as to reduce the oxygen content of the tungsten material to below 5 ppm.

[0047] Through reasonable control of the refining temperature and time, the present invention enables the full melting of tungsten waste while promoting the gasification and volatilization of gaseous or highly volatile impurities such as iron and silicon.

[0048] By using a crystallizer for cooling treatment, the present invention makes the refined tungsten form a large-grain structure, improves the material purity and uniformity, and can make the grain size of tungsten reach more than 500 μm to improve the creep resistance of the material.

[0049] Those skilled in the art should understand that the present invention is not limited by the above embodiments. The above embodiments and the descriptions in the specification only illustrate the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed. The scope of the present invention claimed is defined by the appended claims and their equivalents.

Claims

1. A method for refining high-purity tungsten based on a plasma beam furnace, characterized in that, It includes the following steps: First step: After pre-removing surface contaminants from tungsten metal waste, press it to obtain tungsten raw materials, load them into a crucible, and then perform vacuum treatment; Second step: Add the tungsten raw materials treated in the first step into a plasma beam melting furnace in an inert gas atmosphere, gradually raise the temperature until the alloy melts, and then keep it warm. Use the plasma beam for high-temperature refining to make it reach a state of partial melting or evaporation; Third step: After the impurities volatilize from low boiling point to high boiling point, use an impurity cooling and collection device to collect them; Fourth step: Cool, machine or heat-treat the refined and purified tungsten material to obtain a high-purity tungsten product.

2. The high-purity tungsten refining method based on a plasma beam furnace according to claim 1, characterized in that, The pre-removal is pickling followed by drying treatment.

3. The high-purity tungsten refining method based on a plasma beam furnace according to claim 1, characterized in that, The inert gas atmosphere is a mixed gas of hydrogen and helium or a mixed gas of hydrogen and argon, The volume ratio of hydrogen in the mixed gas is 0 - 5%.

4. A high-purity tungsten refining method based on a plasma beam furnace according to claim 1, characterized in that, The refining temperature is 4000°C - 5000°C, and the refining time is 15 - 30 minutes.

5. A method for refining high-purity tungsten based on a plasma beam furnace according to claim 1, characterized in that, The heat preservation in the plasma beam melting furnace is to control the melting temperature of the plasma beam melting furnace at 1400°C and then gradually raise the temperature until the alloy melts and then keep it warm.

6. A high-purity tungsten refining method based on a plasma beam furnace according to claim 1, characterized in that, The low-boiling-point impurities are Fe, Si, Al, and O impurities.

7. A method for refining high-purity tungsten based on a plasma beam furnace according to claim 1, characterized in that, The tungsten metal waste is tungsten metal powder waste, tungsten metal chip waste, tungsten metal block waste, and irregular-shaped waste impurities of tungsten metal.

8. A high-purity tungsten refining method based on a plasma beam furnace according to claim 1, characterized in that, The cooling is carried out using a crystallizer for cooling treatment.