Method and system for recovering tungsten-based alloy waste based on molten salt bath

Abstract

The invention provides a method and system for recycling tungsten-based alloy waste based on a molten salt bath. The method comprises the steps that the tungsten-based alloy waste serves as an anode, a solid conductive material serves as a cathode, molten salt bath electrolysis is carried out, after molten salt bath electrolysis is finished, a mixture of molten salt and an electrolysis product is mixed with a carbon source, molten salt bath carbonization is carried out, and tungsten carbide powder or tungsten-based alloy composite powder is obtained. According to the method, diversified, low-cost, recycling and high-value utilization of the tungsten-based alloy waste is achieved, the application range of the types of the tungsten-based alloy waste is wide, and the method is also suitable for the tungsten-based alloy waste with complex components; and the tungsten carbide powder or the tungsten-based alloy composite powder can be obtained in a shorter time and under the condition that the temperature is obviously lower than the traditional carbonization temperature, the tungsten-based alloy composite powder can be directly regenerated and sintered into the tungsten-based alloy, and the method provides a new thought for preparing the tungsten carbide powder or the tungsten-based alloy composite powder.

Description

Technical Field

[0001] The present invention relates to the technical field of sustainable recycling of tungsten resources, and in particular to a method and system for recycling tungsten-based alloy waste based on a molten salt bath. The core of the present invention is to use the molten salt bath technology to provide a new solution for the recycling and reuse of tungsten-based alloy waste. Background Art

[0002] Tungsten-based alloys play a vital role in various fields of modern industry due to their excellent physical and chemical properties. For example, tungsten-based alloys are used to manufacture electrodes and electronic equipment components in the field of electronic products, to manufacture reactor tools in the chemical industry, and to produce tools, molds and drills in the field of hardware and electromechanical. These applications demonstrate the key role of tungsten-based alloys in promoting technological progress and industrial development. However, with the widespread application of tungsten-based alloy materials, the amount of waste generated after the end of their service life is also increasing. The treatment and recycling of these wastes is not only related to resource conservation and reduction of production costs, but also an important issue of environmental protection and sustainable development. The effective recycling of tungsten-based alloy waste can not only reduce the demand for new resource mining and reduce resource consumption, but also significantly reduce environmental pollution and promote the green transformation of the economy. Faced with this challenge, how to achieve efficient and environmentally friendly recycling and reuse of tungsten waste has become an urgent problem to be solved. This is not only a technical issue, but also a key way to achieve a circular economy and sustainable development.

[0003] With the increasing global demand for tungsten resources and the growing awareness of environmental protection, the recycling technology of tungsten-based alloy waste is becoming increasingly important. Faced with the limitations of traditional physical and chemical recycling methods, an innovative solution is urgently needed that can improve recycling efficiency while taking into account environmental protection and cost-effectiveness. Summary of the invention

[0005] The present invention aims to solve one of the technical problems in the prior art at least to some extent. To this end, one object of the present invention is to provide a method and system for recycling tungsten-based alloy waste based on a molten salt bath.

[0006] At present, the target products of WC powder and metal composite powders such as WC and Co are long process routes, high energy consumption, and high requirements for the content of raw materials. For example, when recycling high-purity or WC-coated waste, the traditional process is to directly oxidize and roast it at a high temperature above 1000°C to obtain WO3 products, and then reduce it with CH4 or C at a reduction temperature of more than 1000°C to obtain WC products. For another example, when recycling tungsten-based alloy waste (tungsten waste with different cobalt contents, the Co content is usually less than 20%), the traditional process is to oxidize and roast the waste at a high temperature above 1000°C to obtain CoWO4 and WO3 products, and then reduce it with CH4 or C at a reduction temperature of more than 1000°C to obtain WC and Co composite products. Regardless of the treatment method used, the entire process is complicated to operate, and the temperature is above 1000°C, which consumes a lot of energy and is costly.

[0007] In view of this, in a first aspect of the present invention, a method for recovering tungsten-based alloy waste based on a molten salt bath is proposed.

[0008] The tungsten-based alloy scrap is used as the anode and the solid conductive material is used as the cathode to carry out molten salt bath electrolysis. After the molten salt bath electrolysis is completed, a mixture of the molten salt and the electrolysis product is added with a carbon source for molten salt bath carbonization to obtain tungsten carbide powder or tungsten-based alloy composite powder.

[0009] By using tungsten-based alloy scrap as the anode and solid conductive material as the cathode for molten salt bath electrolysis, an electrolysis product with relatively complex composition is obtained. During the electrolysis process, the molten salt bath acts as the anode electrochemical dissolution to play the role of ion transfer. When the electrolysis is completed, the above mixture (molten salt and electrolysis product) in a high-temperature state is simultaneously mixed with a carbon source in a carbonization furnace device for molten salt bath carbonization. In the molten salt bath carbonization process, the molten salt bath plays the role of providing a reaction environment and catalyzing the increase of active sites, which promotes a more complete reaction between the electrolysis product (Co-W alloy phase, tungsten and carbon-deficient phase, etc.) and carbon, and increases the contact reaction probability between the two. The ideal product, i.e., tungsten carbide powder or tungsten-based alloy composite powder, can be obtained in a shorter time and significantly lower than the traditional carbonization temperature.

[0010] In addition, the tungsten carbide powder or tungsten-based alloy composite powder prepared by the above method of the present invention has a purity of more than 99.5%, and the trace elements added in the waste material will also be enriched in the powder product. In this process, no impurity elements other than the trace elements in the waste material will be introduced. A small amount of trace elements has a certain solubility in the molten salt and is accumulated and enriched in the molten salt. In particular, when preparing tungsten-based alloy composite powder, the cobalt in the waste material can be fully reused to obtain a tungsten-based alloy composite material that can directly prepare WC-Co alloy, and the molten salt electrolyte can be recycled after treatment, thereby improving the utilization rate of resources. The conversion rate of carbide powder and tungsten-based alloy composite powder prepared by recycling waste material is close to 100%, that is, all tungsten and cobalt in the waste material are converted into WC or WC, Co. The present invention provides a new idea and a new path for preparing tungsten carbide powder or tungsten-based alloy composite powder.

[0011] Furthermore, trace impurity elements are accumulated and enriched in the molten salt, thereby improving the purity of the electrolysis product. After being purified and impurity-removed, the molten salt is recycled and used again as an electrolyte for the molten salt bath electrolysis.

[0012] In some embodiments of the present invention, when recycling high-purity or WC-coated waste, during the molten salt bath electrolysis process, the anode is electrochemically dissolved, and electrochemical reduction deposition is performed at the cathode. The deposition product phases are W, W2C, and WC. After carbonization in a molten salt bath, WC powder is prepared. The technical principle is: the deposited W and C are reduced, and the C atoms grow on the adsorption sites of the W atoms, and further synthesize W2C and WC. The WC coating C dissolved in the anode is utilized, but the amount is insufficient, resulting in the presence of W and W2C in the product. After carbonization in a molten salt bath, WC powder is obtained.

[0013] In some embodiments of the present invention, when recycling tungsten-based alloy waste, in the molten salt bath electrolysis process, electrochemical dissolution is performed at the anode, and electrochemical reduction deposition is performed at the cathode. The deposition product phase is relatively complex, and WC and Co mixed powder are prepared after carbonization in the molten salt bath. The technical principle is: the reduced deposited W, C, and Co undergo alloying reactions to generate alloy phases such as W, WC, W2C, Co3W, Co6W6C, and Co7W6, and WC and Co composite powders are prepared after carbonization in the molten salt bath.

[0014] It should be noted that the source of the tungsten waste of the present invention is not limited to high-purity tungsten waste such as tungsten electrodes and tungsten rods, waste sprayed with tungsten carbide coatings, tungsten steel, drill bits, tools, molds and other cobalt-containing (cobalt content ranging from 1% to 25%) tungsten-based alloy waste.

[0015] The solid conductive material is a conventional material in the art, and those skilled in the art may select it according to actual conditions. For example, the solid conductive material includes but is not limited to a graphite plate (500 mm×500 mm×10 mm), a stainless steel rod (φ20 mm), or a tungsten rod (φ20 mm).

[0016] Preferably, the heating method of the present invention can be provided by an industrial furnace or a high-temperature flue gas waste heat recovery system, which can efficiently extract waste heat and convert it into usable thermal energy; and the molten salt and electrolysis products are discharged from the electrolytic cell equipment to the carbonization furnace device for molten salt bath carbonization, and the heat of the melt can be utilized, thereby reducing dependence on electrical energy, saving energy consumption and reducing costs.

[0017] Preferably, the tungsten-based alloy waste is first cleaned with an acid or alkali solution to remove oil stains and then polished to remove the oxide layer to ensure that the surface of the waste is clean for use.

[0018] In some embodiments of the present invention, for waste materials of irregular shapes and sizes, during the electrolysis process, they are placed in a perforated anode basket, and the perforated anode basket is connected to the anode rod. Preferably, the anode basket has a size of φ80 mm×100 mm, a hole diameter of φ5 mm, and is made of corundum for molten salt mass transfer.

[0019] According to the above-mentioned method for treating tungsten-based alloy waste of the present invention, molten salt bath electrolysis and molten salt bath carbonization are carried out under the protection of at least one inert atmosphere of Ar or N2.

[0020] In some embodiments of the present invention, the temperature of the molten salt bath carbonization is 750°C to 900°C, and the carbonization time is 0.5 h to 2.0 h. For example, the carbonization temperature is 750°C, 800°C, 850°C, 900°C, etc., or the range between any two of the above values; the time is 0.5 h, 1.0 h, 1.5 h, 2.0 h, etc., or the range between any two of the above values. The temperature used in the present invention is significantly lower than the carbonization temperature of the traditional process, that is, it can be achieved at a temperature between 750°C and 900°C, thereby significantly reducing energy consumption and saving costs.

[0021] In some embodiments of the present invention, the particle size of the carbon source used in the molten salt bath carbonization is 100 nm to 5 μm. For example, the particle size of the carbon source is 100 nm, 200 nm, 800 nm, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, etc., or a range between any two of the above values. The present invention uses a carbon source within the above particle size range to improve the degree and efficiency of carbonization.

[0022] Furthermore, the carbon source used in the carbonization includes but is not limited to at least one of graphite powder and carbon black.

[0023] In some embodiments of the present invention, constant current electrolysis is used, and the current of the molten salt bath electrolysis is 1.0 A to 10 A. For example, the current is 1.0 A, 2.0 A, 4.0 A, 7.0 A, 10 A, etc., or a range between any two of the above values. The present invention uses a current in the above range, and the obtained electrolysis product is easier to carbonize, thereby improving the degree of carbonization and efficiency.

[0024] In some embodiments of the present invention, constant voltage electrolysis is adopted, and the voltage of the molten salt bath electrolysis is 3.0 V to 8.0 V. For example, the voltage is 3.0 V, 4.0 V, 5.0 V, 6.0 V, 7.0 V, 8.0 V, etc., or the range between any two values ​​of the above points. The present invention adopts the voltage in the above range, and the obtained electrolysis product is easier to carbonize, thereby improving the carbonization degree and efficiency.

[0025] Preferably, the temperature of the molten salt bath electrolysis is 750°C to 900°C.

[0026] In some embodiments of the present invention, the electrolyte used in the molten salt bath electrolysis includes chloride salt or tungstate.

[0027] As an example, the tungstate includes but is not limited to at least one of sodium tungstate, potassium tungstate, and calcium tungstate.

[0028] As an example, the chloride salt includes but is not limited to at least one of NaCl-KCl (molar ratio 1:1), LiCl-KCl (molar ratio 3:2).

[0029] In some embodiments of the present invention, the electrolyte is tungstate, and the cathode is placed at the bottom of the container containing the electrolyte. When tungstate is used as the electrolyte, if a conventional rod-shaped electrode inserted into the electrolyte is used as the cathode, it will be oxidized by the tungstate when the cathode peels off after reduction deposition. Therefore, the cathode is placed at the bottom of the container, for example, a plate-shaped cathode graphite plate is placed at the bottom of the container.

[0030] In some embodiments of the present invention, the electrolyte is a chloride salt, and the cathode is inserted into the electrolyte or the cathode is placed at the bottom of a container containing the electrolyte. Chloride salts will not cause oxidation of cathode reduction deposition products, so a conventional cathode can be used.

[0031] In a second aspect of the present invention, the present invention provides a system for implementing the above-mentioned method for recovering tungsten-based alloy waste based on a molten salt bath. Figure 1 The system includes a molten salt bath electrolysis component 100 and a molten salt bath carbonization component 200.

[0032] The molten salt bath electrolysis assembly 100 includes an electrolytic cell 110, an anode electrode rod 120 and a cathode electrode rod 130, and the electrolytic cell 110 is provided with a mixed material outlet 140; The molten salt bath carbonization assembly 200 includes a carbonization chamber 210 , and the carbonization chamber 210 is provided with a carbon source inlet 220 , a mixture inlet 230 and a product outlet 240 . The mixture inlet 230 is connected to the mixture outlet 140 .

[0033] The electrolyte 10 is placed in the electrolytic cell 110, and the anode basket 20 containing tungsten-based alloy scrap is connected to the anode electrode rod 120. If the electrolyte used is chloride salt, the cathode graphite rod 30 is inserted into the molten salt electrolyte 10. If tungstate is used as the electrolyte, the graphite plate 40 is used as the cathode and placed at the bottom of the electrolytic cell 110. The tungsten-based alloy scrap is electrolyzed in the electrolytic cell 110. After the electrolysis is completed, the mixture is discharged from the mixture outlet 140 and then enters the carbonization chamber 210 through the mixture inlet 230. The carbon source is added to perform molten salt bath carbonization. After the molten salt bath carbonization is completed, the product can be discharged from the product outlet 240. It can be understood by those skilled in the art that valves are set at the mixture outlet 140, the product outlet 240 and the carbon source inlet 220 to ensure the progress of the reaction.

[0034] In some embodiments of the present invention, the mixed material outlet 140 is disposed at the lower end of the side wall of the electrolytic cell 110 .

[0035] In some embodiments of the present invention, the mixed material inlet 230 is disposed on a side wall of the carbonization chamber 210 .

[0036] In some embodiments of the present invention, the carbon source inlet 220 is disposed at the top of the carbonization chamber 210, and a feeding bin 250 is disposed at the carbon source inlet 220. The feeding bin 250 contains the carbon source, and the carbon source can be added according to the usage amount.

[0037] In some embodiments of the present invention, a stirring paddle 260 is provided in the carbonization chamber 210. The stirring paddle 260 accelerates the carbonization reaction in the molten salt bath.

[0038] In some embodiments of the present invention, the mixture outlet 240 is disposed at the lower end of the side wall of the carbonization chamber 210 or at the bottom of the carbonization chamber 210 .

[0039] The tungsten carbide powder prepared by the invention has high purity and can be applied to the fields of cemented carbide production, electronic industry, aerospace and aviation.

[0040] The tungsten-based alloy composite powder prepared by the present invention can be directly used to prepare tungsten-based alloys. The tungsten-based alloy composite material has high purity and can be applied to the fields of medical equipment, electronic industry, aerospace, etc.

[0041] The present invention has at least the following technical effects: (1) The present invention realizes the diversified, low-cost, recycling and high-value utilization of tungsten-based alloy waste, which not only significantly improves the recycling efficiency, but also realizes the in-situ regeneration and high-value utilization of waste, which is fully in line with the concept of green and sustainable development. The recycling and reuse of tungsten-based alloy waste of the present invention will become an important force to promote the transformation of the entire industry towards a more environmentally friendly, more economical and more efficient direction.

[0042] (2) The present invention is applicable to a wide range of waste materials, and is also applicable to tungsten-based alloy waste with complex components. For tungsten-based alloy waste with different cobalt contents, the molten salt bath electrolysis product can be carbonized in the molten salt bath to form a tungsten-based alloy composite powder in situ, which can be directly regenerated and sintered into a tungsten-based alloy. The method of the present invention is easy to realize continuous, low-cost, efficient and environmentally friendly batch processing of tungsten-based alloy waste. A closed loop is formed within the technical route, which will not cause secondary pollution, and realizes the in-situ regeneration and high-value utilization of tungsten-based alloy waste, which is fully in line with the concept of green and sustainable development. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0044] Figure 1 It is a schematic diagram of the structure of a device for recovering tungsten-based alloy waste by using a molten salt bath provided by the present invention; Figure 2 is the XRD pattern of the WC powder prepared in Example 1 of the present invention; Figure 3 is the XRD spectrum of the WC and Co composite powder prepared in Example 2 of the present invention; Figure 4 is the XRD spectrum of the WC and Co composite powder prepared in Example 3 of the present invention; Figure 5 is the XRD spectrum of the WC, Co composite powder prepared in Example 4 of the present invention; Figure 6 This is the XRD spectrum of the WC, Co composite powder prepared in Example 6 of the present invention. DETAILED DESCRIPTION

[0045] Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. The present invention is described below with reference to specific embodiments. It should be noted that these embodiments are merely illustrative and do not limit the present invention in any way.

[0046] Example 1

[0047] In this embodiment, tungsten waste sprayed with tungsten carbide coating is used as anode, waste of different shapes and specifications is placed in a perforated anode basket, alkali metal oxygen salt is used as molten salt bath, and the graphite plate at the bottom of the electrolytic cell is used as the working electrode. After the electrolysis is completed, it is discharged into the carbonization furnace and carbonized in the molten salt bath to prepare WC powder. The specific steps are as follows: (1) The tungsten waste for spraying tungsten carbide coating (waste from CVD and other spraying processes) is cleaned and polished to remove surface impurities and oxide layers, etc., and is put into use after a series of pre-treatment processes; (2) Dehydrate industrial sodium tungstate by vacuum drying at 150°C for 24 hours for later use; (3) After pretreatment, tungsten scraps of different shapes and sizes sprayed with tungsten carbide coating are placed in a perforated anode basket. The bottom of the electrolytic cell is made of conductive graphite plate, and molten salt is added to the electrolytic cell; (4) Under the protection of an inert atmosphere, after the molten salt bath reaches a molten state, place the lower electrode and connect the electrochemical workstation. The electrolysis temperature is 800 °C, and the constant current electrolysis method is adopted. The current is 1.5 A, and the constant current electrolysis is performed for 8 h. (5) After the electrolysis is completed, the electrode is raised above the surface of the molten salt bath, and the electrolysis products and molten salt are discharged into the carbonization furnace at high temperature. Carbon powder is added (the amount added is calculated according to the amount of anode dissolution, and the molar ratio of tungsten to carbon is 1:1). The auxiliary heating system raises the temperature of the carbonization furnace to 750 °C. The carbonization treatment is carried out for 0.5 h. After the molten salt bath carbonization is completed, WC powder is prepared.

[0048] The purity of the tungsten carbide powder prepared in this embodiment is 99.85%. The XRD pattern of the WC powder is as follows: Figure 2 As shown. Figure 2 It can be seen that WC powder is prepared in this embodiment.

[0049] Example 2

[0050] In this embodiment, cobalt-containing tungsten-based alloy waste is used as the anode, and wastes of different shapes and specifications are placed in a perforated anode basket, alkali metal oxygen salt is used as a molten salt bath, and the graphite plate at the bottom of the electrolytic cell is used as a working electrode. After the electrolysis is completed, it is discharged into a carbonization furnace, and the molten salt bath is carbonized to prepare WC and Co composite powder. The specific steps are as follows: (1) Cobalt-containing tungsten-based alloy scrap (drill bit, cobalt content <10%) is cleaned with 5-10% HCl solution and 5% NaOH solution to remove surface oil stains, and mechanically polished to remove surface impurities and oxide layers, etc., and then put into use after a series of pre-treatment processes; (2) Dehydrate industrial sodium tungstate by vacuum drying at 150°C for 24 hours for later use; (3) After pretreatment, the cobalt-containing tungsten-based alloy scrap of different shapes and sizes is placed in a perforated anode basket. The bottom of the electrolytic cell is made of a conductive graphite plate, and molten salt is added to the electrolytic cell; (4) Under the protection of an inert atmosphere, after the molten salt bath reaches a molten state, place the lower electrode, connect a DC power supply, set the electrolysis temperature at 775 °C, use a constant current electrolysis method, and perform constant current electrolysis for 30 h with a current of 6.0 A; (5) After the electrolysis is completed, the electrode is raised above the surface of the molten salt bath, and the electrolysis products and molten salt are discharged into the carbonization furnace at high temperature. Carbon powder is added (the amount added is determined according to the content of tungsten carbon-deficient phase and tungsten-cobalt alloy phase in the electrolysis products, and the mass ratio is about 1:0.1). The auxiliary heating system raises the temperature of the carbonization furnace to 800 °C. The carbonization treatment is carried out for 0.5 h. After the molten salt bath carbonization is completed, WC and Co composite powder are prepared. The tungsten-based alloy composite powder can be directly used for the sintering preparation of tungsten-based alloy materials.

[0051] The purity of the tungsten-based alloy composite powder prepared in this embodiment is 99.78%. The XRD spectrum of the WC and Co composite powders is as follows: Figure 3 As shown. Figure 3 It can be seen that WC and Co composite powders were prepared in this embodiment.

[0052] Example 3

[0053] In this embodiment, cobalt-containing tungsten-based alloy waste is used as the anode, and wastes of different shapes and specifications are placed in a perforated anode basket, alkali metal oxygen salt is used as a molten salt bath, and the graphite plate at the bottom of the electrolytic cell is used as a working electrode. After the electrolysis is completed, it is discharged into a carbonization furnace, and the molten salt bath is carbonized to prepare WC and Co composite powder. The specific steps are as follows: (1) Tungsten-based alloy waste (mold, cobalt content 10%~15%) is cleaned of surface oil stains using 5~10% HCl solution and 5% NaOH solution, and mechanically polished to remove surface impurities and oxide layers, etc., and then put into use after a series of pre-treatment processes; (2) Dehydrate industrial sodium tungstate by vacuum drying at 150°C for 24 hours for later use; (3) After pretreatment, the cobalt-containing tungsten-based alloy scrap of different shapes and sizes is placed in a perforated anode basket. The bottom of the electrolytic cell is made of a conductive graphite plate, and molten salt is added to the electrolytic cell; (4) Under the protection of an inert atmosphere, after the molten salt bath reaches a molten state, place the lower electrode, connect a DC power supply, set the electrolysis temperature to 775 °C, use a constant voltage electrolysis method, and perform constant voltage electrolysis for 15 h at a voltage of 4.0 V; (5) After the electrolysis is completed, the electrode is raised above the surface of the molten salt bath, and the electrolysis product and the molten salt are discharged into the carbonization furnace at high temperature. Carbon powder is added (the amount added is determined according to the content of tungsten carbon-deficient phase and tungsten-cobalt alloy phase in the electrolysis product, and the mass ratio is about 1:0.08). The auxiliary heating system raises the temperature of the carbonization furnace to 750°C. The carbonization treatment is carried out for 1.5 hours. After the molten salt bath carbonization is completed, WC and Co composite powder are prepared. The tungsten-based alloy composite powder can be directly used for the sintering preparation of tungsten-based alloy materials.

[0054] The purity of the tungsten-based alloy composite powder prepared in this embodiment is 99.73%. The XRD spectrum of the WC and Co composite powders is as follows: Figure 4 As shown. Figure 4 It can be seen that WC and Co composite powders were prepared in this embodiment.

[0055] Example 4

[0056] In this embodiment, cobalt-containing tungsten-based alloy waste is used as the anode, and wastes of different shapes and specifications are placed in a perforated anode basket, alkali metal oxygen salt is used as a molten salt bath, and the graphite plate at the bottom of the electrolytic cell is used as a working electrode. After the electrolysis is completed, it is discharged into a carbonization furnace, and the molten salt bath is carbonized to prepare WC and Co composite powder. The specific steps are as follows: (1) Cobalt-containing tungsten-based alloy scrap (cutting parts, cobalt content > 15%) is cleaned with 5-10% HCl solution and 5% NaOH solution to remove surface oil stains, and mechanically polished to remove surface impurities and oxide layers, etc., and then put into use after a series of pre-treatment processes; (2) Dehydrate industrial sodium tungstate by vacuum drying at 150°C for 24 hours for later use; (3) After pretreatment, the cobalt-containing tungsten-based alloy scrap of different shapes and sizes is placed in a perforated anode basket. The bottom of the electrolytic cell is made of a conductive graphite plate, and molten salt is added to the electrolytic cell; (4) Under the protection of an inert atmosphere, after the molten salt bath reaches a molten state, place the lower electrode, connect a DC power supply, set the electrolysis temperature at 775 °C, use a constant current electrolysis method, and perform constant current electrolysis for 24 h with a current of 10.0 A; (5) After the electrolysis is completed, the electrode is raised above the surface of the molten salt bath, and the electrolysis product and the molten salt are discharged into the carbonization furnace at high temperature. Carbon powder is added (the amount added is determined according to the content of tungsten carbon-deficient phase and tungsten-cobalt alloy phase in the electrolysis product, and the mass ratio is about 1:0.05). The auxiliary heating system raises the temperature of the carbonization furnace to 800 °C. The carbonization treatment is carried out for 1.0 h. After the molten salt bath carbonization is completed, WC and Co composite powder are prepared. The tungsten-based alloy composite powder can be directly used for the sintering preparation of tungsten-based alloy materials.

[0057] The purity of the tungsten-based alloy composite powder prepared in this embodiment is 99.67%. The XRD spectrum of the WC and Co composite powders is as follows: Figure 5 As shown. Figure 5 It can be seen that WC and Co composite powders were prepared in this embodiment.

[0058] Example 5

[0059] In this embodiment, cobalt-containing tungsten-based alloy waste is used as the anode, and waste of different shapes and specifications are placed in a perforated anode basket to serve as a molten salt bath. The graphite plate at the bottom of the electrolytic cell serves as the working electrode. After the electrolysis is completed, it is discharged into the carbonization furnace and carbonized in the molten salt bath to prepare WC and Co composite powder. The specific steps are as follows: (1) Cobalt-containing tungsten-based alloy scrap (cutting parts, cobalt content > 15%) is cleaned with 5-10% HCl solution and 5% NaOH solution to remove surface oil stains, and mechanically polished to remove surface impurities and oxide layers, etc., and then put into use after a series of pre-treatment processes; (2) Dehydrate industrial sodium tungstate by vacuum drying at 150°C for 24 hours for later use; (3) After pretreatment, the cobalt-containing tungsten-based alloy scrap of different shapes and sizes is placed in a perforated anode basket. The bottom of the electrolytic cell is made of a conductive graphite plate, and molten salt is added to the electrolytic cell; (4) Under the protection of an inert atmosphere, after the molten salt bath reaches a molten state, place the lower electrode, connect a DC power supply, set the electrolysis temperature to 775 °C, use a constant voltage electrolysis method, and perform constant voltage electrolysis for 15 h at a voltage of 5.0 V; (5) After the electrolysis is completed, the electrode is raised above the surface of the molten salt bath, and the electrolysis product and the molten salt are discharged into the carbonization furnace at high temperature. Carbon powder is added (the amount added is determined according to the content of tungsten carbon-deficient phase and tungsten-cobalt alloy phase in the electrolysis product, and the mass ratio is about 1:0.06). The auxiliary heating system raises the temperature of the carbonization furnace to 850°C. The carbonization treatment is carried out for 0.5h. After the molten salt bath carbonization is completed, WC and Co composite powder are prepared. The tungsten-based alloy composite powder can be directly used for the sintering preparation of tungsten-based alloy materials.

[0060] The purity of the tungsten-based alloy composite powder prepared in this embodiment is 99.76%. In this embodiment, WC and Co composite powder are prepared.

[0061] Example 6

[0062] In this embodiment, cobalt-containing tungsten-based alloy waste is used as the anode, and wastes of different shapes and specifications are placed in a perforated anode basket, alkali metal chloride is used as a molten salt bath, and the graphite plate at the bottom of the electrolytic cell is used as a working electrode. After the electrolysis is completed, it is discharged into a carbonization furnace, and the molten salt bath is carbonized to prepare WC and Co composite powder. The specific steps are as follows: (1) Cobalt-containing tungsten-based alloy scrap (cutting parts, cobalt content > 15%) is cleaned with 5-10% HCl solution and 5% NaOH solution to remove surface oil stains, and mechanically polished to remove surface impurities and oxide layers, etc., and then put into use after a series of pre-treatment processes; (2) Mix NaCl and KCl in a molar ratio of 1:1 and vacuum dry them at 150 °C for 24 h for dehydration. (3) After pretreatment, the cobalt-containing tungsten-based alloy scrap of different shapes and sizes is placed in a perforated anode basket. The bottom of the electrolytic cell is made of a conductive graphite plate, and molten salt is added to the electrolytic cell; (4) Under the protection of an inert atmosphere, after the molten salt bath reaches a molten state, place the lower electrode, connect a DC power supply, set the electrolysis temperature at 750 °C, use a constant current electrolysis method, and perform constant current electrolysis for 10 h with a current of 4.0 A; (5) After the electrolysis is completed, the electrode is raised above the salt bath liquid level, and the electrolysis products and molten salt are discharged into the carbonization furnace at high temperature. Carbon powder is added (the amount added is determined according to the content of tungsten carbon-deficient phase and tungsten-cobalt alloy phase in the electrolysis products, and the mass ratio is about 1:0.06). The auxiliary heating system raises the temperature of the carbonization furnace to 750 °C. The carbonization treatment is carried out for 1.5 h. After the molten salt bath carbonization is completed, WC and Co composite powder are prepared. The tungsten-based alloy composite powder can be directly used for the sintering preparation of tungsten-based alloy materials.

[0063] The purity of the tungsten-based alloy composite powder prepared in this embodiment is 99.74%. The XRD spectrum of the WC and Co composite powders is as follows: Figure 6 As shown. Figure 6 It can be seen that WC and Co composite powders were prepared in this embodiment.

[0064] Finally, it should be noted that the above 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 with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for recovering tungsten-based alloy waste based on a molten salt bath, characterized in that: include: The tungsten-based alloy scrap is used as the anode and the solid conductive material is used as the cathode to carry out molten salt bath electrolysis. After the molten salt bath electrolysis is completed, a mixture of the molten salt and the electrolysis product is added with a carbon source for molten salt bath carbonization to obtain tungsten carbide powder or tungsten-based alloy composite powder.

2. The method according to claim 1, characterized in that: The temperature of the molten salt bath carbonization is 750°C to 900°C, and the time of the molten salt bath carbonization is 0.5 h to 2.0 h; And / or, the particle size of the carbon source used in the molten salt bath carbonization is 100 nm to 5 μm; And / or, the carbon source used in the molten salt bath carbonization includes at least one of graphite powder and carbon black.

3. The method according to claim 1 or 2, characterized in that: Constant current electrolysis is adopted, and the current of the molten salt bath electrolysis is 1.0 A ~ 10 A; And / or, constant voltage electrolysis is adopted, and the voltage of the molten salt bath electrolysis is 3.0 V to 8.0 V; And / or, the temperature of the molten salt bath electrolysis is 750°C to 900°C.

4. The method according to claim 1 or 2, characterized in that: The electrolyte used in the molten salt bath electrolysis includes chloride salt or tungstate.

5. The method according to claim 4, characterized in that: The electrolyte is tungstate, and the cathode is placed at the bottom of a container containing the electrolyte; And / or, the tungstate includes at least one of sodium tungstate, potassium tungstate, and calcium tungstate.

6. The method according to claim 4, characterized in that: The electrolyte is a chloride salt, the cathode is inserted into the electrolyte or the cathode is placed at the bottom of a container containing the electrolyte; And / or, the chloride salt includes at least one of NaCl-KCl and LiCl-KCl.

7. The method according to claim 1 or 2, characterized in that: Trace impurity elements are accumulated and enriched in the molten salt, thereby improving the purity of the electrolysis product. After being purified and impurity-removed, the molten salt is recycled and reused as the electrolyte for the molten salt bath electrolysis.

8. A system for implementing the method for recovering tungsten-based alloy waste based on a molten salt bath as described in any one of claims 1 to 7, characterized in that: include: A molten salt bath electrolysis assembly, the molten salt bath electrolysis assembly comprising an electrolytic cell, an anode electrode rod and a cathode electrode rod, the electrolytic cell being provided with a mixture outlet; A molten salt bath carbonization component comprises a carbonization chamber, wherein the carbonization chamber is provided with a carbon source inlet, a mixture inlet and a product outlet, and the mixture inlet is connected to the mixture outlet.

9. The system according to claim 8, characterized in that: The mixed material outlet is arranged at the lower end of the side wall of the electrolytic cell; And / or, the mixed material inlet is arranged on the side wall of the carbonization chamber; And / or, the carbon source inlet is arranged at the top of the carbonization chamber, and a feeding bin is arranged at the carbon source inlet; And / or, the mixed material outlet is arranged at the lower end of the side wall of the carbonization chamber or the bottom end of the carbonization chamber.

10. The system according to claim 8 or 9, characterized in that: A stirring paddle is arranged in the carbonization chamber.

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