Method for recovering tungsten carbide and cobalt from waste tungsten-cobalt hard alloy

Abstract

The invention provides a method for recovering tungsten carbide and cobalt from waste tungsten-cobalt hard alloy, and belongs to the technical field of tungsten-cobalt hard alloy recovery. The method for recovering the tungsten carbide and the cobalt from the waste tungsten-cobalt hard alloy comprises the following steps that a deep eutectic solvent and cobalt chloride are mixed, and an electrolyte is obtained; the eutectic solvent comprises a hydrogen bond acceptor and a hydrogen bond donor, the hydrogen bond acceptor is chlorinated organic ammonium salt, and the hydrogen bond donor is ethylene glycol or organic acid; and the waste tungsten-cobalt hard alloy serves as an anode, precious metal or transition metal serves as a cathode, the anode and the cathode are immersed into the electrolyte for electrolysis, tungsten carbide is obtained on the anode, and metal cobalt is obtained on the cathode. According to the method, the eutectic solvent is adopted as the electrolyte, and tungsten carbide and cobalt in the waste tungsten-cobalt hard alloy are recycled in the electrolyte, so that harmful gases such as hydrogen chloride can be prevented from being generated, the use amount of raw materials is reduced, and the method is safe and environment-friendly.

Description

Technical Field

[0001] The invention belongs to the technical field of recycling tungsten-cobalt hard alloys, and in particular relates to a method for recycling tungsten carbide and cobalt from waste tungsten-cobalt hard alloys. Background Art

[0002] Cemented carbide has high hardness, high melting point, high strength, excellent wear resistance and corrosion resistance, and is widely used in key fields such as microelectronics, mechanical processing, mineral development, aerospace and defense industry. The production of cemented carbide consumes a large amount of tungsten resources, and the large-scale use of cemented carbide products also produces a large amount of cemented carbide waste. The effective recycling and reuse of waste tungsten-cobalt cemented carbide can not only alleviate the pressure on my country's demand for tungsten and cobalt resources, but also has great significance for establishing a resource security system and promoting the development of a circular economy.

[0003] At present, the methods for recovering tungsten carbide and cobalt from waste tungsten-cobalt cemented carbides mainly include zinc melting, mechanical crushing, high-temperature treatment, sodium sulfate smelting, electrolysis, etc. These recovery methods are all to remove the bond between tungsten carbide and binder, thereby achieving the separation of tungsten carbide and binder in waste tungsten-cobalt cemented carbides. However, among the above recovery methods, the zinc melting method has high energy consumption and low purity of the recovered product; the mechanical crushing method has the problem of high equipment cost and incomplete cobalt phase separation; the high-temperature treatment method has high energy consumption and low product performance; in comparison, the electrolysis method has low energy consumption and high product purity, so it is widely favored.

[0004] The traditional electrolytic recycling of waste tungsten-cobalt cemented carbide is to use it as the anode and the inert electrode as the cathode. The cathode and anode are placed in an electrolytic cell, and an acid aqueous solution (such as hydrochloric acid and sulfuric acid) is used as the electrolyte. Direct current is connected, and the cobalt in the waste tungsten-cobalt cemented carbide is electrochemically dissolved into the solution at the anode and precipitated on the cathode. The remaining tungsten carbide is deposited at the bottom of the electrolytic cell, and then further processed to obtain tungsten carbide powder.

[0005] However, the traditional electrolyte for waste tungsten-cobalt cemented carbide is mainly an acidic system such as hydrochloric acid. In the production process of extracting tungsten carbide and cobalt from waste tungsten-cobalt cemented carbide by electrochemical method under this acidic system, the cobalt ions in the waste tungsten-cobalt cemented carbide react chemically with the chloride ions in the hydrochloric acid. Under the action of electric current, the chemical reaction intensifies, and a large amount of hydrogen chloride gas escapes from the tank. The amount of hydrochloric acid used is large, and there are great safety and health hazards, which seriously restricts the development of green comprehensive utilization of secondary resources of waste tungsten-cobalt cemented carbide. Summary of the invention

[0006] The object of the present invention is to provide a method for recovering tungsten carbide and cobalt from waste tungsten-cobalt cemented carbide. The present invention adopts a low eutectic solvent as an electrolyte, and recovers tungsten carbide and cobalt from waste tungsten-cobalt cemented carbide in the electrolyte, which can avoid the generation of harmful gases such as hydrogen chloride, reduce the amount of raw materials, and is safe and environmentally friendly.

[0007] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0008] The present invention provides a method for recovering tungsten carbide and cobalt from waste tungsten-cobalt cemented carbide, comprising the following steps:

[0009] Mixing a low eutectic solvent with cobalt chloride to obtain an electrolyte; the components of the low eutectic solvent include a hydrogen bond acceptor and a hydrogen bond donor, the hydrogen bond acceptor is an organic ammonium chloride salt, and the hydrogen bond donor is ethylene glycol or an organic acid;

[0010] Using waste tungsten-cobalt hard alloy as anode and noble metal or transition metal as cathode, the anode and cathode are immersed in the electrolyte for electrolysis, tungsten carbide is obtained on the anode, and metal cobalt is obtained on the cathode.

[0011] Preferably, the organic ammonium chloride salt includes at least one of choline chloride, trimethylbenzylammonium chloride, triethylbenzylammonium chloride, tripropylbenzylammonium chloride, tributylbenzylammonium chloride, trimethylethylbenzylammonium chloride, methyltrioctylammonium chloride, methyltriethylammonium chloride, methyltributylammonium chloride, tetramethylammonium chloride, tetraethylammonium chloride, tetrapropylammonium chloride and tetrabutylammonium chloride.

[0012] Preferably, the organic acid comprises at least one of p-toluenesulfonic acid, methanesulfonic acid, malonic acid, tartaric acid, salicylic acid, citric acid, succinic acid and adipic acid.

[0013] Preferably, the molar ratio of the hydrogen bond acceptor to the hydrogen bond donor is 1:1-3.

[0014] Preferably, the concentration of cobalt chloride in the electrolyte is 0.1-1.0 mol / L.

[0015] Preferably, the mass fraction of Co in the waste tungsten-cobalt cemented carbide is not less than 8%.

[0016] Preferably, the components of the waste tungsten-cobalt cemented carbide include WC, Co, Ni, Fe, Si and Ti; in the waste tungsten-cobalt cemented carbide, the mass fraction of Co is 8% to 20%, the mass fraction of Ni and Fe combined does not exceed 1.0%, the mass fraction of Si is 0.35% to 0.65wt%, the mass fraction of Ti is 0.12% to 0.2wt%, and the balance is WC.

[0017] Preferably, the noble metal includes platinum; and the transition metal includes cobalt or titanium.

[0018] Preferably, the electrolysis conditions include: voltage of 1.0-2.0 V, temperature of 60-90° C., and time of 16-24 h.

[0019] Preferably, the anode is waste tungsten-cobalt cemented carbide particles loaded in a titanium basket; the particle size of the waste tungsten-cobalt cemented carbide particles does not exceed 10 mm.

[0020] The present invention provides a method for recovering tungsten carbide and cobalt from waste tungsten-cobalt cemented carbide, comprising the following steps: mixing a low eutectic solvent with cobalt chloride to obtain an electrolyte; the components of the low eutectic solvent include a hydrogen bond acceptor and a hydrogen bond donor, the hydrogen bond acceptor is an organic ammonium chloride salt, and the hydrogen bond donor is ethylene glycol or an organic acid; using waste tungsten-cobalt cemented carbide as an anode and a noble metal or a transition metal as a cathode, immersing the anode and the cathode in the electrolyte for electrolysis, obtaining tungsten carbide on the anode and metallic cobalt on the cathode. In the present invention, the low eutectic solvent has low cost, is green and non-toxic, has good thermal stability, has extremely low vapor pressure at room temperature, does not produce harmful gases such as hydrogen chloride, is more environmentally friendly, and has a safer operating environment when used; wherein, there is a strong coordination interaction force between the organic ammonium chloride salt and cobalt, thereby forming cobalt tetrachloride complex ions, thereby enhancing the conductivity of the electrolyte. In the present invention, cobalt chloride can enhance the conductivity of the electrolyte on the one hand, and is conducive to the deposition of metallic cobalt on the cathode surface on the other hand; and cobalt ions and chloride ions can stably exist in the form of cobalt tetrachloride complex ions in the low eutectic solvent, thereby enhancing the conductivity of the electrolyte and reducing the viscosity of the electrolyte; using the electrolyte to recover tungsten carbide and cobalt in waste tungsten-cobalt cemented carbides can avoid the generation of harmful gases such as hydrogen chloride, reduce the amount of raw materials, and be safe and environmentally friendly. Moreover, the low eutectic solvent used in the present invention has a reducing property, which can inhibit the formation of a passivation film on the surface of waste tungsten-cobalt cemented carbides, such as tungstic acid, tungsten oxide, cobalt oxide, etc., can effectively reduce the hardening, improve the electrolysis efficiency of waste tungsten-cobalt cemented carbides, and promote the deposition of tungsten carbide and the dissolution of cobalt. Waste tungsten-cobalt cemented carbides are electrolyzed in an electrolyte containing a low eutectic solvent. Since the electrolysis environment is an anhydrous environment, the hydrogen evolution reaction can be effectively avoided, thereby making cobalt have good adhesion on the cathode. The electrolyte of the present invention can fully electrolyze waste tungsten-cobalt cemented carbide, avoid the waste of metal in the raw material, and obtain a high yield of tungsten carbide. The embodiment shows that the purity of tungsten carbide obtained by the method of the present invention is not less than 99.8%, the dissolution rate of cobalt is not less than 98%, and the purity of cobalt is not less than 99%.

[0021] Furthermore, the low eutectic solvent used in the present invention has a wide electrochemical window, is relatively stable to water and air, is inexpensive, has high solubility of metal salts, and will not have a negative impact on the environment. Moreover, compared with the existing process, the method of the present invention is environmentally friendly, has high electrolysis efficiency for waste tungsten-cobalt cemented carbide, consumes less reagents, has low cost, does not produce acidic wastewater, and has good engineering application value and economic value. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0023] Figure 1 A flow chart for recovering tungsten carbide and cobalt from waste tungsten-cobalt cemented carbide by electrolysis using a low eutectic solvent;

[0024] Figure 2 This is the XRD pattern of the tungsten carbide powder obtained in Example 1. DETAILED DESCRIPTION

[0025] The present invention provides a method for recovering tungsten carbide and cobalt from waste tungsten-cobalt cemented carbide, comprising the following steps:

[0026] Mixing a low eutectic solvent with cobalt chloride to obtain an electrolyte; the components of the low eutectic solvent include a hydrogen bond acceptor and a hydrogen bond donor, the hydrogen bond acceptor is an organic ammonium chloride salt, and the hydrogen bond donor is ethylene glycol or an organic acid;

[0027] Using waste tungsten-cobalt hard alloy as anode and noble metal or transition metal as cathode, the anode and cathode are immersed in the electrolyte for electrolysis, tungsten carbide is obtained on the anode, and metal cobalt is obtained on the cathode.

[0028] In the present invention, unless otherwise specified, the raw materials used are commercially available products well known to those skilled in the art or are prepared by methods well known to those skilled in the art.

[0029] The components of the electrolyte of the present invention include a low eutectic solvent. In the present invention, the components of the low eutectic solvent include a hydrogen bond acceptor and a hydrogen bond donor, the hydrogen bond acceptor is an organic ammonium chloride salt, and the hydrogen bond donor is an organic acid. In the present invention, the organic ammonium chloride salt may include at least one of choline chloride, trimethylbenzyl ammonium chloride, triethylbenzyl ammonium chloride, tripropylbenzyl ammonium chloride, tributylbenzyl ammonium chloride, trimethylethylbenzyl ammonium chloride, methyltrioctyl ammonium chloride, methyltriethylammonium chloride, methyltributylammonium chloride, tetramethylammonium chloride, tetraethylammonium chloride, tetrapropylammonium chloride and tetrabutylammonium chloride; the organic acid may include at least one of p-toluenesulfonic acid, methanesulfonic acid, malonic acid, tartaric acid, salicylic acid, citric acid, succinic acid and adipic acid. In a specific embodiment of the present invention, the hydrogen bond acceptor is choline chloride and the hydrogen bond donor is ethylene glycol. The present invention can dry the hydrogen bond acceptor and the hydrogen bond donor separately, and then mix the dried hydrogen bond acceptor and hydrogen bond donor in proportion to obtain a low eutectic solvent. In the present invention, the drying temperature can be 70-90°C, and the time can be 20-30h; in a specific embodiment of the present invention, the drying temperature is 80°C, and the time is 24h. In the present invention, the molar ratio of the hydrogen bond acceptor to the hydrogen bond donor can be 1:1-3; in a specific embodiment of the present invention, the molar ratio of the hydrogen bond acceptor to the hydrogen bond donor is 1:1, 1:2 or 1:3. In the present invention, the hydrogen bond acceptor and the hydrogen bond donor can be mixed under stirring. The stirring temperature of the present invention can be 60-90°C, and the time can be 30-60min; in a specific embodiment of the present invention, the stirring temperature is 60°C, 70°C, 80°C or 90°C, and the time is 30min, 40min, 50min or 60min. In the present invention, the organic ammonium chloride salt is used as a hydrogen bond acceptor, and ethylene glycol or an organic acid is used as a hydrogen bond donor; wherein, there is a strong coordination interaction force between the organic ammonium chloride salt and cobalt, thereby forming a cobalt tetrachloride complex ion, thereby enhancing the conductivity of the electrolyte; ethylene glycol and organic acid are reducing, and the low eutectic solvent obtained therefrom is reducing, which can inhibit the formation of a passivation film on the surface of waste tungsten-cobalt cemented carbide, such as tungstic acid, tungsten oxide, cobalt oxide, etc., can effectively reduce the caking, improve the electrolysis efficiency of waste tungsten-cobalt cemented carbide, and promote the deposition of tungsten carbide and the dissolution of cobalt. Moreover, the low eutectic solvent is green and non-toxic, has good thermal stability, does not produce harmful gases such as hydrogen chloride, and is more environmentally friendly.

[0030] The components of the electrolyte of the present invention include cobalt chloride. In the electrolyte of the present invention, the concentration of cobalt chloride is 0.1-1.0 mol / L; in a specific embodiment of the present invention, the concentration of cobalt chloride in the electrolyte can be 0.1 mol / L, 0.3 mol / L, 0.5 mol / L, 0.8 mol / L or 1.0 mol / L. In the present invention, cobalt chloride can enhance the conductivity of the electrolyte on the one hand, and is conducive to the deposition of metallic cobalt on the cathode surface on the other hand; and cobalt ions and chloride ions can stably exist in the form of cobalt tetrachloride complex ions in a low eutectic solvent, thereby enhancing the conductivity of the obtained electrolyte and reducing the viscosity of the electrolyte.

[0031] The present invention mixes a low eutectic solvent with cobalt chloride to obtain an electrolyte. In the present invention, the low eutectic solvent and cobalt chloride can be mixed under stirring. The stirring temperature of the present invention can be 60 to 90°C, and the time can be 30 to 60 minutes; in a specific embodiment of the present invention, the stirring temperature is 60°C, 70°C, 80°C or 90°C, and the time is 30 minutes, 40 minutes, 50 minutes or 60 minutes.

[0032] After obtaining the electrolyte, the present invention uses waste tungsten-cobalt hard alloy as an anode and a precious metal or a transition metal as a cathode, immerses the anode and cathode into the electrolyte for electrolysis, obtains tungsten carbide on the anode, and obtains metal cobalt on the cathode.

[0033] In the present invention, the tungsten-cobalt cemented carbide in the waste tungsten-cobalt cemented carbide is a YG series cemented carbide, which is a cemented carbide composed of cobalt (Co) as the main bonding phase and a small amount of other elements (mainly tungsten carbide WC). The elements in the waste tungsten-cobalt cemented carbide of the present invention include W, C, Co, Ni, Fe, Si and Ti. In the waste tungsten-cobalt cemented carbide of the present invention, the mass fraction of Co may not be less than 8%; in a specific embodiment of the present invention, the mass fraction of Co in the waste tungsten-cobalt cemented carbide is 8% to 20%. In the waste tungsten-cobalt cemented carbide of the present invention, the mass fraction of Ni and Fe in total may not exceed 1.0%; in a specific embodiment of the present invention, the mass fraction of Ni in the waste tungsten-cobalt cemented carbide is 0.42%, and the mass fraction of Fe is 0.56%. In the waste tungsten-cobalt cemented carbide of the present invention, the mass fraction of Si may be 0.35% to 0.65wt%; in a specific embodiment of the present invention, the mass fraction of Si in the waste tungsten-cobalt cemented carbide is 0.65%. In the waste tungsten-cobalt cemented carbide of the present invention, the mass fraction of Ti may be 0.12% to 0.2wt%. In a specific embodiment of the present invention, the mass fraction of Ti in the waste tungsten-cobalt cemented carbide is 0.12%.

[0034] In the present invention, before the electrolysis, the waste tungsten-cobalt cemented carbide may be sequentially washed, polished, crushed and ultrasonically treated to obtain waste tungsten-cobalt cemented carbide particles. In the present invention, the reagent used for washing may be a sodium hydroxide aqueous solution, and the mass fraction of the sodium hydroxide aqueous solution may be 5% to 10%; in a specific embodiment of the present invention, the reagent used for washing is a sodium hydroxide aqueous solution with a mass fraction of 10%. The present invention removes suspended matter, oil stains and impurities on the surface of waste tungsten-cobalt cemented carbide by washing. After the washing, the present invention may use sandpaper to polish the washed waste tungsten-cobalt cemented carbide, and then use an air hammer to crush the polished waste tungsten-cobalt cemented carbide to obtain waste tungsten-cobalt cemented carbide particles. In the present invention, the specification of the sandpaper may be 80 to 1000 meshes; in a specific embodiment of the present invention, the specification of the sandpaper may be 100 to 400 meshes. The particle size of the waste tungsten-cobalt cemented carbide particles of the present invention may not exceed 10 mm. The present invention removes the oxide layer on the surface of waste tungsten-cobalt cemented carbide by grinding to enhance the conductivity; crushing can increase the contact surface between the waste tungsten-cobalt cemented carbide and the electrolyte and improve the electrolysis efficiency. The present invention can place the waste tungsten-cobalt cemented carbide particles in anhydrous ethanol or acetone for ultrasonic treatment. In the present invention, the power of the ultrasonic treatment can be 20 to 40 kHz, and the time can be 10 to 30 minutes; in a specific embodiment of the present invention, the power of the ultrasonic treatment is 20kHz, 30kHz or 40kHz; the time is 10 minutes, 20 minutes or 30 minutes. The present invention removes the moisture brought by the previous washing by ultrasonic treatment. The present invention can load the waste tungsten-cobalt cemented carbide particles in a titanium basket as an anode.

[0035] In the present invention, the noble metal includes platinum, and the transition metal includes cobalt or titanium. In a specific embodiment of the present invention, the cathode is a platinum sheet, a cobalt sheet or a titanium sheet.

[0036] In the present invention, the electrolysis conditions include: voltage can be 1.0-2.0V, temperature can be 60-90°C, and time can be 16-24h. In a specific embodiment of the present invention, the electrolysis conditions include: voltage is 1.0V, 1.5V or 2.0V; temperature is 60°C, 70°C, 80°C or 90°C; time is 16h, 18h, 20h, 22h or 24h.

[0037] After the electrolysis is completed, the present invention obtains tungsten carbide on the anode. The present invention can crush and grind the tungsten carbide on the anode in sequence to obtain tungsten carbide powder. In the present invention, the particle size of the tungsten carbide powder can be 1 to 4 μm. The tungsten carbide powder of the present invention includes the following components: WC, Co, Ni, Fe, S and Ti; the mass fraction of Co can be 0.050% to 0.105%, the sum of the mass fractions of Ni and Fe can be 0.0055% to 0.0072%, the mass fraction of Si can be 0.0310 to 0.0345%, the mass fraction of Ti can be 0.0103% to 0.0236%, and the remainder is WC. In a specific embodiment of the present invention, the mass fraction of Co is 0.078%, the sum of the mass fractions of Ni and Fe is 0.0057%, the mass fraction of Si is 0.0311%, the mass fraction of Ti is 0.0105%, and the remainder is WC. In another specific embodiment of the present invention, the mass fraction of Co is 0.052%, the sum of the mass fractions of Ni and Fe is 0.0063%, the mass fraction of Si is 0.0311%, the mass fraction of Ti is 0.0205%, and the balance is WC. In another specific embodiment of the present invention, the mass fraction of Co is 0.102%, the sum of the mass fractions of Ni and Fe is 0.0071%, the mass fraction of Si is 0.0342%, the mass fraction of Ti is 0.0236%, and the balance is WC. In the present invention, the yield of tungsten carbide may be no less than 98%; in a specific embodiment of the present invention, the yield of tungsten carbide is 98.5%, 98.9% or 99.2%.

[0038] After the electrolysis is completed, the present invention obtains metallic cobalt on the cathode. The present invention can wash and dry the cobalt on the cathode in sequence to obtain cobalt powder. In the present invention, the washing can be an alternating alcohol washing and water washing; the reagent used for the alcohol washing can be anhydrous ethanol, the number of alcohol washings can be 3 to 5 times; the number of water washings can be 3 to 5 times. In a specific embodiment of the present invention, the number of alcohol washings is 3 times, 4 times or 5 times; the number of water washings is 3 times, 4 times or 5 times. The washing of the present invention can be carried out under ultrasonic conditions, and the frequency of the ultrasound can be 20 to 40kHz; in a specific embodiment of the present invention, the frequency of the ultrasound is 20kHz, 30kHz or 40kHz. In the present invention, the drying can be vacuum drying, the drying temperature can be 60 to 90°C, and the time can be 1 to 3h; in a specific embodiment of the present invention, the drying temperature is 60°C, 70°C, 80°C or 90°C; the time is 1h, 2h or 3h. In the present invention, the particle size of the cobalt powder can be 2 to 5μm. In the present invention, the dissolution rate of the cobalt powder may be no less than 98%; in a specific embodiment of the present invention, the dissolution rate of the cobalt powder is 98.1%, 98.6% or 99.6%. The purity of the cobalt powder of the present invention may be no less than 99%; in a specific embodiment of the present invention, the purity of the cobalt powder is 99.2%, 99.6% or 99.7%.

[0039] The present invention electrolyzes waste tungsten-cobalt cemented carbide in an electrolyte containing a low eutectic solvent, which can effectively avoid hydrogen evolution reaction, and the cobalt has good adhesion to the cathode; the method of the present invention can achieve sufficient electrolytic treatment of waste tungsten-cobalt cemented carbide, avoid the waste of metal in the raw material, and the obtained tungsten carbide has a high yield and good purity.

[0040] The technical solutions in the present invention will be described clearly and completely below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. 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.

[0041] The flow chart of using low eutectic solvent electrolysis to recover tungsten carbide and cobalt from waste tungsten-cobalt cemented carbide is as follows: Figure 1 shown.

[0042] The waste tungsten-cobalt cemented carbide used in the embodiment comes from recycled cemented carbide rods, and its components include WC, Co, Ni, Fe, Si and Ti; wherein the mass fraction of Co is 15%, the mass fraction of Ni is 0.42%, the mass fraction of Fe is 0.56%, the mass fraction of Si is 0.65wt%, the mass fraction of Ti is 0.12%, and the balance is WC.

[0043] Example 1

[0044] (1) Choline chloride and ethylene glycol are placed in a vacuum drying oven and dried at 80° C. for 24 h. Then, the dried choline chloride and ethylene glycol are weighed into a flask in a molar ratio of 1:2, and stirred and mixed at 80° C. for 30 min to obtain a low eutectic solvent (transparent liquid).

[0045] Weigh 7.9 g of anhydrous cobalt chloride and put it into a flask containing 300 mL of a low eutectic solvent. Seal the mouth of the flask with a rubber stopper and stir at 80° C. until the anhydrous cobalt chloride is completely dissolved to obtain an electrolyte (dark blue transparent liquid). Place the electrolyte in an electrolytic cell for later use.

[0046] (2) The waste tungsten-cobalt cemented carbide is washed with a sodium hydroxide aqueous solution having a mass fraction of 10% to remove suspended matter, oil stains and impurities on the surface thereof, and then the washed waste tungsten-cobalt cemented carbide is polished with sandpaper (with a specification of 100 to 400 meshes), and then the waste tungsten-cobalt cemented carbide is crushed into waste tungsten-cobalt cemented carbide particles with a particle size of less than 10 mm by an air hammer.

[0047] (3) The waste tungsten-cobalt cemented carbide particles are ultrasonically treated in anhydrous ethanol for 20 minutes and then placed in a titanium basket as an anode, and a titanium sheet as a cathode. The anode and the cathode are immersed in an electrolytic cell containing the electrolyte obtained in step (1), and the electrolysis is carried out for 16 hours at 90° C. and a cell voltage of 1.5 V, powered by a DC regulated power supply. After the electrolysis, loosely stacked tungsten carbide particles are obtained on the anode, and cobalt particles are obtained on the cathode.

[0048] (4) Remove the tungsten carbide particles on the anode, crush and grind them in turn to obtain tungsten carbide powder (particle size is 1-4 μm). Use ultrasound (30 kHz) to peel off the cobalt particles on the cathode, and wash the obtained cobalt particles alternately with anhydrous ethanol and deionized water under ultrasound (30 kHz), and wash them with anhydrous ethanol and deionized water three times each; after the last water washing, place the obtained cobalt powder in a vacuum oven and dry it at 60°C for 1 hour to obtain cobalt powder (particle size is 2-5 μm).

[0049] The XRD pattern of the tungsten carbide powder obtained in Example 1 is as follows: Figure 2 As shown, the components of tungsten carbide powder are as follows: Co is 0.078wt%; Ni+Fe is 0.0057wt%; Si is 0.0311wt%; Ti is 0.0105wt%, and the balance is WC; the yield of tungsten carbide is 98.5%.

[0050] The purity of the cobalt powder obtained in Example 1 was 99.6%, and the dissolution rate of the binder phase cobalt was 98.6%.

[0051] Example 2

[0052] (1) Place choline chloride and ethylene glycol in a vacuum drying oven and dry at 80°C for 24 hours, then weigh the dried choline chloride and ethylene glycol into a flask at a molar ratio of 1:1, and stir and mix at 60°C for 60 minutes to obtain a low eutectic solvent (transparent liquid). Weigh 19.5 g of anhydrous cobalt chloride and place it in a flask containing 300 mL of a low eutectic solvent, seal the flask with a rubber stopper, and stir at 60°C until the anhydrous cobalt chloride is completely dissolved to obtain an electrolyte (dark blue transparent liquid), which is placed in an electrolytic cell for standby use.

[0053] The waste tungsten-cobalt cemented carbide is washed with a sodium hydroxide aqueous solution with a mass fraction of 10% to remove suspended matter, oil stains and impurities on its surface, and then the washed waste tungsten-cobalt cemented carbide is polished with sandpaper (with a specification of 100-400 meshes), and then the waste tungsten-cobalt cemented carbide is crushed into waste tungsten-cobalt cemented carbide particles with a particle size less than 10 mm with an air hammer.

[0054] (3) The waste tungsten-cobalt cemented carbide particles are ultrasonically treated in anhydrous ethanol for 20 minutes and then placed in a titanium basket as an anode, and a titanium sheet as a cathode. The anode and the cathode are immersed in an electrolytic cell containing the electrolyte obtained in step (1), and the electrolysis is carried out for 20 hours at 60° C. and a cell voltage of 2.0 V, powered by a DC regulated power supply. After the electrolysis, loosely accumulated tungsten carbide particles are obtained on the anode, and cobalt particles are obtained on the cathode.

[0055] (4) Remove the tungsten carbide particles on the anode, crush and grind them in turn to obtain tungsten carbide powder (particle size is 1-4 μm). Use ultrasound (30 kHz) to peel off the cobalt particles on the cathode, and wash the obtained cobalt particles alternately with anhydrous ethanol and deionized water under ultrasound (30 kHz), and wash them with anhydrous ethanol and deionized water three times each; after the last water washing, place the obtained cobalt powder in a vacuum oven and dry it at 60°C for 1 hour to obtain cobalt powder (particle size is 2-5 μm).

[0056] The components of the tungsten carbide powder obtained in Example 2 are as follows: Co is 0.052wt%; Ni+Fe is 0.0063wt%; Si is 0.0311wt%; Ti is 0.0205wt%, and the balance is WC; the yield of tungsten carbide is 98.9%.

[0057] The purity of the cobalt powder obtained in Example 2 was 99.2%, and the dissolution rate of the binder phase cobalt was 99.6%.

[0058] Example 3

[0059] (1) Place choline chloride and ethylene glycol in a vacuum drying oven and dry at 80°C for 24 hours, then weigh the dried choline chloride and ethylene glycol into a flask at a molar ratio of 1:3, and stir and mix at 90°C for 40 minutes to obtain a low eutectic solvent (transparent liquid). Weigh 19.5 g of anhydrous cobalt chloride and place it in a flask containing 300 mL of a low eutectic solvent, seal the flask with a rubber stopper, and stir at 90°C until the anhydrous cobalt chloride is completely dissolved to obtain an electrolyte (dark blue transparent liquid), which is placed in an electrolytic cell for standby use.

[0060] The waste tungsten-cobalt cemented carbide is washed with a sodium hydroxide aqueous solution with a mass fraction of 10% to remove suspended matter, oil stains and impurities on its surface, and then the washed waste tungsten-cobalt cemented carbide is polished with sandpaper (with a specification of 100-400 meshes), and then the waste tungsten-cobalt cemented carbide is crushed into waste tungsten-cobalt cemented carbide particles with a particle size less than 10 mm with an air hammer.

[0061] (3) The waste tungsten-cobalt cemented carbide particles are ultrasonically treated in anhydrous ethanol for 20 minutes and then placed in a titanium basket as an anode, and a titanium sheet as a cathode. The anode and the cathode are immersed in an electrolytic cell containing the electrolyte obtained in step (1), and the electrolysis is carried out for 24 hours at 90° C. and a cell voltage of 1.0 V, powered by a DC regulated power supply. After the electrolysis, loosely stacked tungsten carbide particles are obtained on the anode, and cobalt particles are obtained on the cathode.

[0062] (4) Remove the tungsten carbide particles on the anode, crush and grind them in turn to obtain tungsten carbide powder (particle size is 1-4 μm). Use ultrasound (30 kHz) to peel off the cobalt particles on the cathode, and wash the obtained cobalt particles alternately with anhydrous ethanol and deionized water under ultrasound (30 kHz), and wash them with anhydrous ethanol and deionized water three times each; after the last water washing, place the obtained cobalt powder in a vacuum oven and dry it at 60°C for 1 hour to obtain cobalt powder (particle size is 2-5 μm).

[0063] The components of the tungsten carbide powder obtained in Example 3 are as follows: Co is 0.102wt%; Ni+Fe is 0.0071wt%; Si is 0.0342wt%; Ti is 0.0236wt%, and the balance is WC; the yield of tungsten carbide is 99.2%.

[0064] The purity of the cobalt powder obtained in Example 3 was 99.7%, and the dissolution rate of the binder phase cobalt was 98.1%.

[0065] Comparative Example 1

[0066] Tungsten carbide and cobalt are recovered from waste tungsten-cobalt cemented carbide in the manner and conditions of Example 1, except that the electrolyte of Example 1 is adjusted to hydrochloric acid with a concentration of 1.5 mol / L.

[0067] The components of the tungsten carbide powder obtained in Comparative Example 1 are as follows: Co is 0.101wt%; Ni+Fe is 0.0069wt%; Si is 0.0312wt%; Ti is 0.024wt%, and the balance is WC; the yield of tungsten carbide is 96%.

[0068] The purity of the cobalt powder obtained in Comparative Example 1 was 96.7%, and the dissolution rate of the binder phase cobalt was 98.2%.

[0069] Obviously, the yield of tungsten carbide and the purity of cobalt powder in Comparative Example 1 are significantly lower than those in Examples 1 to 3. It can be seen that the yield of tungsten carbide and the purity of cobalt powder obtained by treating waste tungsten-cobalt cemented carbide using the method provided by the present invention can effectively improve.

[0070] Although the above embodiment describes the present invention in detail, it is only a part of the embodiments of the present invention, not all of the embodiments. People can also obtain other embodiments based on this embodiment without creativity, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method for recovering tungsten carbide and cobalt from waste tungsten-cobalt cemented carbide, characterized in that: The following steps are involved: Mixing a low eutectic solvent with cobalt chloride to obtain an electrolyte; the components of the low eutectic solvent include a hydrogen bond acceptor and a hydrogen bond donor, the hydrogen bond acceptor is an organic ammonium chloride salt, and the hydrogen bond donor is ethylene glycol or an organic acid; Using waste tungsten-cobalt hard alloy as anode and noble metal or transition metal as cathode, the anode and cathode are immersed in the electrolyte for electrolysis, tungsten carbide is obtained on the anode, and metal cobalt is obtained on the cathode.

2. The method according to claim 1, characterized in that The chlorinated organic ammonium salt includes at least one of choline chloride, trimethylbenzylammonium chloride, triethylbenzylammonium chloride, tripropylbenzylammonium chloride, tributylbenzylammonium chloride, trimethylethylbenzylammonium chloride, methyltrioctylammonium chloride, methyltriethylammonium chloride, methyltributylammonium chloride, tetramethylammonium chloride, tetraethylammonium chloride, tetrapropylammonium chloride and tetrabutylammonium chloride.

3. The method according to claim 1, characterized in that The organic acid includes at least one of p-toluenesulfonic acid, methanesulfonic acid, malonic acid, tartaric acid, salicylic acid, citric acid, succinic acid and adipic acid.

4. The method according to any one of claims 1 to 3, characterized in that: The molar ratio of the hydrogen bond acceptor to the hydrogen bond donor is 1:1-3.

5. The method according to claim 1, characterized in that The concentration of cobalt chloride in the electrolyte is 0.1-1.0 mol / L.

6. The method according to claim 1, characterized in that The mass fraction of Co in the waste tungsten-cobalt hard alloy is not less than 8%.

7. The method according to claim 1 or 6, characterized in that: The components of the waste tungsten-cobalt cemented carbide include WC, Co, Ni, Fe, Si and Ti; in the waste tungsten-cobalt cemented carbide, the mass fraction of Co is 8% to 20%, the mass fraction of Ni and Fe combined does not exceed 1.0%, the mass fraction of Si is 0.35% to 0.65wt%, the mass fraction of Ti is 0.12% to 0.2wt%, and the balance is WC.

8. The method according to claim 1, characterized in that The noble metal includes platinum; the transition metal includes cobalt or titanium.

9. The method according to claim 1, characterized in that: The electrolysis conditions include: voltage of 1.0-2.0V, temperature of 60-90°C, and time of 16-24h.

10. The method according to claim 1, characterized in that The anode is waste tungsten-cobalt hard alloy particles loaded in a titanium basket, and the particle size of the waste tungsten-cobalt hard alloy particles does not exceed 10 mm.

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