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WO2014045579A1 - Bain de sel fondu pour la dissolution d'alliage super-dur de wc-co et procédé pour la séparation et la récupération de tungstène et de cobalt - Google Patents

Bain de sel fondu pour la dissolution d'alliage super-dur de wc-co et procédé pour la séparation et la récupération de tungstène et de cobalt Download PDF

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WO2014045579A1
WO2014045579A1 PCT/JP2013/005530 JP2013005530W WO2014045579A1 WO 2014045579 A1 WO2014045579 A1 WO 2014045579A1 JP 2013005530 W JP2013005530 W JP 2013005530W WO 2014045579 A1 WO2014045579 A1 WO 2014045579A1
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molten salt
salt bath
cemented carbide
alkali
tungsten
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Japanese (ja)
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政夫 森下
宏明 山本
政昭 池邉
秀文 柳田
上野　智之
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SANALLOY INDUSTRY Co Ltd
Hyogo Prefectural Government
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SANALLOY INDUSTRY Co Ltd
Hyogo Prefectural Government
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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B23/00—Obtaining nickel or cobalt
    • C22B23/02—Obtaining nickel or cobalt by dry processes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B09—DISPOSAL OF SOLID WASTE; RECLAMATION OF CONTAMINATED SOIL
    • B09B—DISPOSAL OF SOLID WASTE NOT OTHERWISE PROVIDED FOR
    • B09B3/00—Destroying solid waste or transforming solid waste into something useful or harmless
    • B09B3/40—Destroying solid waste or transforming solid waste into something useful or harmless involving thermal treatment, e.g. evaporation
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G41/00—Compounds of tungsten
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G51/00—Compounds of cobalt
    • C01G51/04—Oxides
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B34/00—Obtaining refractory metals
    • C22B34/30—Obtaining chromium, molybdenum or tungsten
    • C22B34/36—Obtaining tungsten
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B7/00—Working up raw materials other than ores, e.g. scrap, to produce non-ferrous metals and compounds thereof; Methods of a general interest or applied to the winning of more than two metals
    • C22B7/001—Dry processes
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2002/00—Crystal-structural characteristics
    • C01P2002/70—Crystal-structural characteristics defined by measured X-ray, neutron or electron diffraction data
    • C01P2002/72—Crystal-structural characteristics defined by measured X-ray, neutron or electron diffraction data by d-values or two theta-values, e.g. as X-ray diagram
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00—Technologies related to metal processing
    • Y02P10/20—Recycling

Definitions

  • the present invention relates to a molten salt bath used for separating and recovering tungsten and cobalt from a WC-Co cemented carbide, and further separating and recovering tungsten and cobalt from a WC-Co cemented carbide dissolved using a molten salt bath. On how to do.
  • tungsten has been widely used as a raw material for filament materials and tungsten carbide (WC) because of its high melting point and elastic modulus.
  • WC is widely used as a material for cemented carbide having a metal such as cobalt as a binder phase.
  • tungsten is not only unevenly distributed, but also has a small amount of output, so it is difficult to supply stably, and the price fluctuates greatly due to slight fluctuations in demand.
  • Cobalt is extremely useful as a magnet material derived from ferromagnetism, and further as an additive element for heat-resistant steel and WC-Co cemented carbide. This cobalt, like tungsten, is not only unevenly distributed, but also has a small amount of output, so that stable supply is difficult, and the price fluctuates greatly with slight fluctuations in demand.
  • a waste material of WC-Co cemented carbide is used at a temperature of 80 ° C. or less using a solution of ferric chloride, ferric oxalate, or cupric chloride, or a solution obtained by adding an inorganic acid to these solutions.
  • a method in which cobalt constituting the binder phase is eluted by dipping at a temperature of 5%, and the residue is pulverized to recover tungsten carbide powder (Patent Document 1).
  • WC-Co cemented carbide waste material is used to recover tungsten carbide by eluting cobalt constituting the binder phase at a temperature of 81-100 ° C using a solution containing ferric chloride and hydrochloric acid.
  • Patent Documents 2 and 3 There are methods to do this.
  • the waste material of WC-Co cemented carbide is immersed in molten metal such as zinc (Zn) or tin (Sn), and the cobalt constituting the binder phase is swollen and divided into WC particles. Thereafter, there is a method in which WC is recovered by evaporating Zn and Sn, and the recovered WC is reused as a WC-Co cemented carbide material (Non-patent Document 1).
  • any of the above-described methods recovers tungsten carbide from a cemented carbide mainly composed of tungsten carbide, and does not collect tungsten and cobalt alone, but a cemented carbide material mainly composed of tungsten carbide. However, it is difficult to reuse as a resource other than cemented carbide.
  • NaNO 3 has a relatively high melting point, it is necessary to heat the NaNO 3 to around 1000K and dissolve the cemented carbide. At such a high temperature, there is a problem that the evaporation loss of molten NaNO 3 is large and the corrosion deterioration of the stainless steel constituting the reaction plant vessel used for melting the cemented carbide is remarkable. Then, in the vicinity of 1000 K, there is a decomposed problem sodium peroxide (Na 2 O 2) and evaporation explode gas molten NaNO 3.
  • the present invention has been proposed in view of such problems, and the technical problem of the present invention is that the WC-Co cemented carbide can be melted at a low temperature, such as stainless steel used for melting the cemented carbide.
  • An object of the present invention is to propose a molten salt bath that can reduce the corrosion damage of a reaction plant vessel formed of steel and has a small evaporation loss.
  • the technical problem of the present invention is to treat a WC—Co cemented carbide melted using a molten salt bath at a low temperature and with a small evaporation loss by using a wet processing technique.
  • the purpose is to separate and recover pure tungsten (W) and cobalt (Co).
  • the present inventors have achieved a molten salt bath that enables efficient dissolution of cemented carbide at low temperatures as a result of intensive studies.
  • the bath is obtained by uniformly melting molten alkali nitrate in molten alkali chloride.
  • alkali chloride and alkali nitrate are difficult to melt uniformly due to the difference in polarity.
  • the present invention has found that an alkali chloride and an alkali nitrate can be uniformly melted, and has realized a molten salt bath of WC-Co cemented carbide.
  • the molten salt bath according to the present invention uniformly melted the molten alkali nitrate in the molten alkali chloride by using the molten alkali chloride as the solvent salt and the molten alkali nitrate as the solute salt.
  • the uniform melting includes a slurry state in which a solid phase is partly crystallized in the molten salt. Further, it includes a state in which a plurality of separated liquid phases are mixed in an emulsion state or a micelle state.
  • the molten alkali chloride and the molten alkali nitrate can be made to have a melting point of 773 K or less by blending them with an appropriate composition, and the evaporation loss can be reduced.
  • the mixed chloride of molten alkali chloride and molten alkali nitrate with reduced melting point and reduced evaporation loss in this way is a reaction plant vessel formed by a steel material such as stainless steel used for melting cemented carbide. It can suppress damage due to corrosion and is useful for a molten salt bath for dissolving WC-Co cemented carbide.
  • the outermost surface of the WC-Co crystal particles is successively converted into WO 3. Oxidation into two-component oxide of Co 3 O 4 and CoO 2 and a three-component double oxide of CoWO 4 is performed to dissolve the WC—Co cemented carbide.
  • molten alkali chloride and molten alkali nitrate constituting the molten salt bath according to the present invention are in a complementary relationship.
  • a molten salt bath made of pure molten NaNO 3 is used for a WC-Co at a low temperature of 773 K or less at which a reaction plant container formed of a steel material such as stainless steel used for melting a cemented carbide does not undergo corrosion deterioration. Cemented carbide cannot be dissolved.
  • the molten salt bath for melting a WC—Co cemented carbide according to the present invention has a chloride ion position in the oxide layer formed on the outermost surface of crystal particles of the WC—Co cemented carbide. Has the effect of replacing. Therefore, the oxide layer produced on the outermost surface of the WC—Co crystal particles is changed to oxytungsten chloride complex ions, and the tungsten component can be rapidly dissolved in the molten salt.
  • the method of the present invention involves immersing a WC-Co cemented carbide in a molten salt bath in which molten alkali nitrate is uniformly melted in molten alkali chloride, and immersing the WC-Co cemented carbide in a molten salt bath.
  • the temperature is raised to about 650 to 1000 K, and the heated state is maintained for a certain period of time to dissolve the WC—Co cemented carbide in the molten salt bath, and then a molten salt bath in which the WC—Co cemented carbide is dissolved.
  • Solidifying to produce a solidified salt and then filtering the aqueous solution produced by adding water to the solidified salt; from this aqueous solution, tungsten-derived tungsten complex salt dissolved and precipitated from the WC-Co cemented carbide; A cobalt oxide derived from cobalt is separated and recovered.
  • pure tungsten and cobalt are separated and recovered by purifying the tungsten-derived tungsten complex salt and cobalt-derived cobalt oxide separated and recovered in the above-described steps.
  • the molten salt bath according to the present invention (1) achieves a low melting point, (2) corrosion of the material constituting the reaction plant vessel used for reducing the evaporation loss and thermal decomposition of the molten salt and dissolving the cemented carbide. By suppressing deterioration, (3) realizing accelerated dissolution of WC-Co cemented carbide, and (4) performing a predetermined purification treatment on the melted WC-Co cemented carbide, Tungsten and pure cobalt can be easily separated and recovered.
  • APT at 873 K is a diagram showing a result of the WO 3 which is produced by thermal decomposition and X-ray spectroscopy (XRD). 2 hours APT at 873 K, the WO 3 which is produced by thermal decomposition, shows the results of 1.5 hours hydrogen thermal reduction and product produced by the X-ray diffraction at 1123 K.
  • the molten salt bath according to the present invention is only required to melt the alkali chloride and the alkali nitrate uniformly when the molten alkali chloride is melted as a solvent salt and the molten alkali nitrate is melted as a solute salt.
  • the melting ratio of alkali nitrate is appropriately selected within the above range.
  • the molten salt bath containing CsNO 3 as part of the alkali nitrate further improves the function of oxidizing the cemented carbide surface and promotes dissolution of the WC—Co cemented carbide.
  • One or more fluorides selected from the above may be substituted.
  • This molten salt bath can further lower the melting point, and realize further reduction of evaporation loss during high-temperature operation. Further, by using this molten salt bath, a function of dissolving the tungsten oxide film formed on the surface of the cemented carbide as an oxytungsten halide complex ion in the molten salt is further provided.
  • Na 2 SO 4 contained in the molten salt greed has an effect of reducing the corrosion deterioration of the stainless steel constituting the reaction plant vessel due to the alkali nitrate. Therefore, a molten salt bath containing Na 2 SO 4 is more beneficial for protecting the reaction plant vessel.
  • any of the above-mentioned molten salt bath and WC—Co cemented carbide are put into a reaction vessel, and the WC—Co cemented carbide is immersed in the molten salt bath.
  • the temperature is raised to about 650 to 1000 K at which the molten salt bath is uniformly melted, preferably to 773 k.
  • the WC—Co cemented carbide is dissolved in the molten salt bath by being immersed in the molten salt bath heated to a predetermined temperature for a predetermined time.
  • the time required for melting the WC—Co cemented carbide is appropriately selected depending on the molten salt bath used and the amount of dissolution.
  • the tungsten component of the WC-Co cemented carbide is dissolved in the molten salt bath as an oxytungsten halide complex ion, and the cobalt component is CoO 4 which is a cobalt oxide. And exfoliated as CoO in a molten salt bath. Then, when the molten salt bath from which the oxytungsten halide complex ion and the cobalt oxide are separated is solidified, a solidified salt containing the oxytungsten halide complex salt and the cobalt oxide is obtained. When warm water is added to this coagulated salt, an aqueous solution is obtained.
  • the tungsten complex salt obtained by dissolving the WC—Co cemented carbide is soluble in water, and the cobalt oxide is insoluble in water.
  • the tungsten complex salt dissolves in the warm water together with the original molten salt component.
  • the cobalt component settles in warm water as oxides CoO 4 and CoO.
  • the cobalt oxides CoO 4 and CoO are recovered as solids, and the tungsten complex salt is separated and recovered as complex ions in the aqueous solution.
  • the cobalt oxides CoO 4 and CoO can be easily recovered as pure cobalt by being subjected to hydrogen thermal reduction.
  • pure tungsten can be separated and recovered by applying a predetermined treatment to the tungsten complex recovered in the filtrate. That is, when calcium chloride (CaCl 2 ) is added to the filtrate in which the tungsten complex is dissolved, calcium tungstate (CaWO 4 ) is generated. Since CaWO 4 produced
  • H 2 WO 4 obtained here is hardly soluble, it precipitates in an aqueous solution.
  • the aqueous solution in which H 2 WO 4 is precipitated is filtered to separate and collect H 2 WO 4 .
  • APT ammonium paratungstate (NH 4 ) 10 (H 2 W 12 O 42 )
  • the time allowed to stand ammonia water having dissolved H 2 WO 4 is appropriately selected depending on the amount of H 2 WO 4 to be introduced to the ammonia water.
  • APT Since APT is sparingly soluble, it is produced along with the reaction and precipitates in ammonia water sequentially. APT crystals can be separated and recovered by evaporating and drying the aqueous solution containing the APT precipitate. When APT crystals are thermally decomposed in oxygen or air, tungsten trioxide (WO 3 ) is obtained. When this WO 3 is hydrothermally reduced, pure tungsten is obtained.
  • the WC—Co cemented carbide is dissolved using the molten salt bath according to the present invention, and the tungsten component and the cobalt component dissolved in the molten salt bath are subjected to the above-described treatment, thereby obtaining a pure water. Tungsten and pure cobalt can be separated and recovered.
  • a molten salt bath having a composition as shown in each experimental example shown in Table 1 below was prepared, and the melting temperature of these molten salt baths was changed, and the WC-Co carbide was immersed in each molten salt bath. The amount of alloy dissolution was measured.
  • the molten salt bath used in each experimental example will be described.
  • the molten salt bath used in Experimental Examples 1 to 3 shown in Table 1 is used for comparison with the molten salt bath according to the present invention, and is conventionally used.
  • the molten NaNO 3 proposed as a melting bath for WC—Co cemented carbide is used.
  • the molten salt baths used in Experimental Examples 4 to 7 shown in Table 1 are obtained by uniformly melting alkali chloride and alkali nitrate, using NaCl and KCl as the alkali chloride and KNO 3 as the alkali nitrate. .
  • the molten salt bath used in Experimental Examples 4 and 5 contains 48 mol% of NaCl, 33 mol% of KCl, and 19 mol% of KNO 3 .
  • the molten salt bath used in Experimental Examples 6 and 7 contains 25 mol% NaCl, 25 mol% KCl, and 50 mol% KNO 3 .
  • the molten salt bath used in Experimental Examples 8 to 10 shown in Table 1 uses LiCl and KCl as the alkali chloride and KNO 3 as the alkali nitrate.
  • the molten salt bath used in Experimental Examples 8 to 10 contains 45 mol% LiCl, 35 mol% KCl, and 20 mol% KNO 3 .
  • the molten salt bath used in Experimental Examples 11 and 12 shown in Table 1 uses LiCl and KCl as the alkali chloride, and uses Na 2 SO 4 which is a sulfate instead of the alkali nitrate.
  • Na 2 SO 4 which is a sulfate, functions as an oxidizing agent.
  • the molten salt bath used in Experimental Examples 11 to 12 contains 53 mol% LiCl, 37 mol% KCl, and 10 mol% Na 2 SO 4 .
  • the molten salt used in Experimental Examples 13 and 14 shown in Table 1 consists only of KNO 3 .
  • the molten salt baths used in Experimental Examples 15 and 16 shown in Table 1 use NaCl and KCl as alkali chlorides and KNO 3 as alkali nitrates, similarly to the molten salt baths used in Experimental Examples 4 to 7. However, the composition ratio is different.
  • the molten salt baths used in Experimental Examples 15 and 16 contain 10 mol% NaCl, 10 mol% KCl, and 80 mol% KNO 3 .
  • the molten salt used in Experimental Example 17 shown in Table 1 is composed only of alkali chloride, and is composed of 58 mol% NaCl and 42 mol% KCl.
  • the molten salt bath used in each experimental example described below was obtained by melting 60 g of a salt having the composition shown in Table 1 in an argon (Ar) stream.
  • a WC—Co cemented carbide having a size of 12.6 mm ⁇ 8.1 mm ⁇ 4.5 mm and a weight of 6.3 g was prepared as a cemented carbide to be melted by being immersed in the molten salt bath.
  • a stainless steel (SUS304) container was used as a reaction container for melting the WC—Co cemented carbide.
  • the dissolution amount of the WC—Co cemented carbide dissolved in the molten salt bath was measured.
  • the dissolution amount of the WC—Co cemented carbide was measured by measuring a solidified salt obtained by solidifying the components dissolved in the molten salt bath.
  • tungsten and cobalt from the WC—Co cemented carbide dissolved in the molten salt bath was performed using the extraction recovery method as described above.
  • the recovery rates of tungsten and cobalt shown in Table 1 are based on the tungsten component and the cobalt component separated and recovered by dissolving in the molten salt bath.
  • the Na 2 WO 4 oxide coating covers the surface of the WC—Co cemented carbide, so Hard alloys cannot be melted.
  • Experimental Example 4 uses a molten salt bath in which alkali chloride and alkali nitrate are uniformly melted.
  • NaCl and KCl were used as the alkali chloride
  • KNO 3 was used as the alkali nitrate.
  • the composition was NaCl 48 mol%, KCl 33 mol%, and KNO 3 19 mol%.
  • the WC—Co cemented carbide was immersed in this molten salt bath, and the temperature of the molten salt bath was set to 873K. At this time, the dissolution amount of the WC—Co cemented carbide in the molten salt bath was 3.52 g as shown in Table 1. This dissolution amount was a large dissolution amount equivalent to the conventionally proposed molten NaNO 3 of 873K.
  • the tungsten component obtained by dissolving the WC—Co cemented carbide in Experimental Example 4 is extracted as a tungsten complex salt soluble in water, and the cobalt component is extracted as CoO 4 and CoO insoluble in water.
  • These tungsten complex salts soluble in water and CoO 4 and CoO insoluble in water can be separated and extracted independently by filtration.
  • the tungsten complex salt and CoO 4 and CoO that are separated and extracted independently can be recovered as pure tungsten and cobalt through the purification process as described above. As shown in Table 1, 95% by weight of the dissolved amount was recovered in the case of tungsten, and 90% by weight of the dissolved amount was recovered in the case of cobalt.
  • the evaporation loss can be further reduced, and the corrosion deterioration of the stainless steel reaction vessel was further reduced.
  • the recovery rates of pure tungsten and cobalt obtained by refining and recovering the tungsten component and the cobalt component obtained by dissolving the WC-Co cemented carbide in Experimental Example 5 are as follows. It was 95% by weight of the dissolved amount, and in the case of cobalt, it was 90% by weight of the dissolved amount.
  • Experimental Example 6 is similar to Experimental Examples 4 and 5, in which alkali chloride and alkali nitrate are uniformly melted. NaCl and KCl are used as alkali chloride, and KNO 3 is used as alkali nitrate. The composition was NaCl 25 mol%, KCl 25 mol%, and KNO 3 50 mol%. In this experimental example, this molten salt bath was set to 873K. As shown in Table 1, the dissolution amount of the WC—Co cemented carbide was 5.79 g. From the results of this experiment, it was confirmed that the dissolution rate of this Experimental Example 6 was about 1.6 times that when melting the WC-Co cemented carbide with molten NaNO 3 at 873 K as in this Experimental Example. .
  • Example 6 pure tungsten and cobalt recovery rates obtained by refining and recovering the tungsten component and cobalt component obtained by melting the WC-Co cemented carbide are shown in Table 1. In this case, the amount was 95% by weight of the dissolved amount, and in the case of cobalt, the amount was 90% by weight.
  • Experimental Example 8 uses a molten salt bath in which alkali chloride and alkali nitrate are uniformly melted.
  • LiCl and KCl were used as the alkali chloride, and KNO 3 was used as the alkali nitrate.
  • the composition was LiCl 45 mol%, KCl 35 mol%, and KNO 3 20 mol%.
  • the WC—Co cemented carbide was immersed in this molten salt bath, and the molten salt bath was set to 873K. As shown in Table 1, the amount of WC—Co cemented carbide dissolved in the molten salt bath at this time was 6.22 g.
  • the amount of dissolution was about 1.5 times as compared with the case of melting the WC—Co cemented carbide with molten NaNO 3 at 973 K at the same temperature.
  • the decrease in the molten salt bath in this experimental example is smaller than that in the case of using molten NaNO 3, and it is recognized that the corrosion deterioration of the reaction vessel is also reduced, and this is applied to industrial tungsten and cobalt dissolution. It is preferable.
  • this molten salt bath was set to 937 K, and the WC-Co cemented carbide was dissolved.
  • the WC—Co cemented carbide can be melted with high efficiency, and damage to the reaction vessel can be effectively prevented while suppressing the decrease of the molten salt bath.
  • Experimental Examples 11 and 12 are sulfate salts that function as oxidizing agents instead of alkali nitrates, and are molten salt baths in which alkali chlorides and sulfates are uniformly melted.
  • LiCl and KCl were used, Na 2 SO 4 was used as the sulfate, and the composition was 53 mol% LiCl, 37 mol% KCl, and 10 mol% Na 2 SO 4 .
  • the WC-Co cemented carbide was dissolved.
  • the temperature of the molten salt bath was 873 K in Experimental Example 11 and 973 K in Experimental Example 12.
  • the dissolution amount of the WC—Co cemented carbide in the molten salt bath in Experimental Examples 11 and 12 was 0.10 g in Experimental Example 11 and 0.88 g in Experimental Example 12. .
  • the recovery rates of pure tungsten and cobalt obtained by refining the tungsten component and the cobalt component obtained by dissolving the WC-Co cemented carbide are as shown in Table 1. For tungsten, it was 75% by weight of the dissolved amount, and for cobalt, it was 90% by weight of the dissolved amount.
  • the molten salt bath configured as shown in Experimental Examples 11 and 12
  • the amount of dissolution was increased when the temperature of the molten salt bath was increased.
  • the temperature of the molten salt bath was increased by 100 K, as apparent from Experimental Examples 11 and 12, the temperature increased by a factor of 8 or more. From these experimental examples, when melting WC-Co cemented carbide in a molten salt bath in which alkali chloride and sulfate are uniformly melted, the molten salt bath is a sufficiently industrial melting step by raising the temperature to 900K or higher. Can be used.
  • the molten salt baths used in Experimental Examples 11 and 12 had a small evaporation loss when heated, and the corrosion deterioration of the stainless steel (SUS304) container constituting the reaction container was reduced. Therefore, the molten salt bath used in Experimental Examples 11 and 12 is useful for industrial tungsten and cobalt recovery processes.
  • Experimental Example 13 is an example in which molten WC—Co cemented carbide was dissolved using molten KNO 3 consisting only of KNO 3 which is an alkali chloride as a molten salt bath.
  • the temperature of molten KNO 3 was set to 873K.
  • the amount of WC—Co cemented carbide dissolved in the molten KNO 3 at this time was 4.87 g as shown in Table 1.
  • the molten salt bath used in Experimental Example 15 uses NaCl and KCl as the alkali chloride and KNO 3 as the alkali nitrate, and the composition is NaCl of 10 mol% and KCl of 10 mol%. KNO 3 is 80 mol%.
  • the molten salt bath used in this experimental example can dissolve WC-Co cemented carbide at a low temperature of 773K, so that the evaporation loss of the molten salt bath at the time of dissolution can be reduced and corrosion deterioration of the reaction vessel can be suppressed. .
  • the WC—Co cemented carbide was dissolved using the same dissolved salt bath as in Experimental Example 15, and the molten salt bath was set to 873K.
  • the amount of WC—Co cemented carbide dissolved in the molten salt bath at this time was 5.94 g as shown in Table 1.
  • the dissolution amount obtained in this experimental example is more than that obtained in Experimental Examples 5 and 7 using a molten salt bath having the same composition as the molten salt bath used in this experimental example, and an extremely large dissolution amount is obtained. Can do.
  • the recovery rate of pure tungsten and cobalt recovered by refining the tungsten component and the cobalt component obtained by dissolving the WC-Co cemented carbide is as follows.
  • the solvent salt bath was composed only of alkaline chlorides LiCl and KCl, and the composition thereof was 58 mol% LiCl and 42 mol% KCl.
  • the molten salt bath in which the WC—Co cemented carbide was immersed was heated to 973 K, but no dissolution of the WC—Co cemented carbide was observed.
  • Table 2 shows a molten salt bath that can dissolve WC-Co cemented carbide at 773K. All of the molten salt baths shown in Table 2 are obtained by uniformly melting alkali chloride and alkali nitrate. Hereinafter, experimental examples shown in Table 2 will be described.
  • a molten salt bath having a composition as shown in Table 2 was filled in a stainless steel (SUS304) reaction vessel, and the molten salt bath was heated to 773K. After immersing a WC-Co cemented carbide alloy having a size of 12.6 mm ⁇ 8.1 mm ⁇ 4.5 mm and a weight of 6.3 g in this molten salt bath for 3 hours, as in the experimental example described above. The dissolved amount of was measured.
  • WC-Co cemented carbide can be dissolved at a temperature of 773 K or less that can suppress alkali nitrate evaporation and suppress thermal decomposition. It has been found that a molten salt bath is obtained.
  • the WC—Co cemented carbide can be dissolved only by adding about 1 mol% of alkali chloride to the molten salt bath.
  • NaNO 3 is used as the alkali nitrate, it is desirable to contain 15 mol% or more of alkali chloride in the molten salt bath in order to obtain a practical amount of dissolution.
  • Table 3 shows experimental examples in which cemented carbide was dissolved using a molten salt bath to which CsCl was added as an alkali chloride and further fluoride was added as a halide component.
  • 773 K is a temperature at which the evaporation loss of the molten salt bath can be suppressed and the thermal decomposition loss can be suppressed.
  • the solidified salt obtained by dissolving the WC—Co cemented carbide in the molten salt bath according to Experimental Examples 18 to 29 described above was prepared in the same manner as in Experimental Examples 4 to 12 and Experimental Examples 15 and 16 described above.
  • the tungsten component is extracted as a tungsten complex salt soluble in water
  • the cobalt component is extracted as CoO 4 and CoO insoluble in water.
  • These water-soluble tungsten complex salts and CoO 4 and CoO that are insoluble in water can be separated and extracted independently by filtering using, for example, filter paper.
  • Pure ammonium can be separated and recovered by evaporating and drying the aqueous ammonium tungstate solution produced here, followed by thermal decomposition and further hydrogen reduction.
  • Example of separation and recovery of tungsten and cobalt Next, a specific example in which pure tungsten and cobalt are recovered from the WC-Co cemented carbide melted using the above-described molten salt bath will be described. In the following description, an example in which pure tungsten and cobalt are recovered from the WC-Co cemented carbide dissolved in the molten salt bath shown in Experimental Example 8 will be described.
  • the tungsten component is dissolved in the molten salt bath as a tungsten complex salt, and the cobalt component is It is dissolved in the molten salt bath as CoO 4 and CoO which are cobalt oxides.
  • the molten salt bath in which the tungsten complex salt and the cobalt oxides CoO 4 and CoO are dissolved is solidified to obtain a solidified salt containing the tungsten complex salt, CoO 4 and CoO.
  • a solidified salt containing the tungsten complex salt, CoO 4 and CoO When hot water is added to the coagulated salt to form an aqueous solution, which is filtered, water-insoluble CoO 4 and CoO and water-soluble tungsten complex salt are separated and recovered.
  • H 2 WO 4 Since H 2 WO 4 is hardly soluble, it precipitates in an aqueous solution. Therefore, the aqueous solution in which H 2 WO 4 is deposited is filtered to separate and recover H 2 WO 4 . When the separated and recovered H 2 WO 4 is put into ammonia water and allowed to stand for 24 hours, APT is precipitated.
  • the APT deposited here is shown in FIG.
  • APT crystals obtained by evaporating and drying the ammonia water on which APT was precipitated were thermally decomposed in 873 K oxygen or air for 2 hours.
  • the material obtained here was subjected to X-ray diffraction.
  • the results are shown in the X-ray spectroscopic analysis (XRD) diagram of FIG. Peak WO 3 was observed in 4, it is shown that the WO 3 is generated.
  • the molten salt bath according to the present invention in which nitrate is uniformly melted is extremely useful for dissolving WC—Co cemented carbide, and can be used for industrial recovery of tungsten and cobalt.

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PCT/JP2013/005530 2012-09-21 2013-09-19 Bain de sel fondu pour la dissolution d'alliage super-dur de wc-co et procédé pour la séparation et la récupération de tungstène et de cobalt Ceased WO2014045579A1 (fr)

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CN104911636A (zh) * 2015-07-06 2015-09-16 中南大学 一种从废弃金刚石刀具中综合回收金刚石及各种金属资源的清洁工艺
EP2952260A1 (fr) * 2014-06-05 2015-12-09 Sandvik Intellectual Property AB Procédé permettant de trier une collection de corps comprenant des corps en carbure cémenté et des corps en carbure non cémenté
CN113512740A (zh) * 2021-06-18 2021-10-19 北京工业大学 一种利用废旧硬质合金制备WC-Co复合粉末的方法
JP7506292B2 (ja) 2022-10-20 2024-06-26 兵庫県公立大学法人 水素製造用触媒の製造方法及び水素製造用触媒

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Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2952260A1 (fr) * 2014-06-05 2015-12-09 Sandvik Intellectual Property AB Procédé permettant de trier une collection de corps comprenant des corps en carbure cémenté et des corps en carbure non cémenté
CN105177326A (zh) * 2014-06-05 2015-12-23 山特维克知识产权股份有限公司 用于对包含硬质合金料体和非硬质合金料体的料体集合进行分选的方法
US9770720B2 (en) 2014-06-05 2017-09-26 Sandvik Intellectual Property Ab Method for sorting a collection of bodies comprising cemented carbide bodies and non-cemented carbide bodies
CN104911636A (zh) * 2015-07-06 2015-09-16 中南大学 一种从废弃金刚石刀具中综合回收金刚石及各种金属资源的清洁工艺
CN104911636B (zh) * 2015-07-06 2017-05-17 中南大学 一种从废弃金刚石刀具中综合回收金刚石及各种金属资源的清洁工艺
CN113512740A (zh) * 2021-06-18 2021-10-19 北京工业大学 一种利用废旧硬质合金制备WC-Co复合粉末的方法
JP7506292B2 (ja) 2022-10-20 2024-06-26 兵庫県公立大学法人 水素製造用触媒の製造方法及び水素製造用触媒

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