Method for recovering high-purity tungsten compound by physicochemical concentration from low-grade ultra-hard soft scrap

Abstract

The present invention provides a method for recovering high-purity tungsten compounds by physicochemical concentration from low-grade hard carbide soft scrap, wherein high-purity WC-Co is recovered by wet crushing and magnetic separation of low-grade hard carbide soft scrap discarded as waste, and then high-purity tungsten compounds are recovered by performing a physicochemical concentration process on the recovered high-purity WC-Co.

Description

Technology Field

[0001] The present invention relates to a method for recovering high-purity tungsten compounds by physicochemical concentration from low-grade hard carbide soft scrap, wherein high-purity WC-Co is recovered by wet crushing and magnetic separation of low-grade hard carbide soft scrap discarded as waste, and then high-purity tungsten compounds are recovered by performing a physicochemical concentration process on the recovered high-purity WC-Co. Background Technology

[0003] Generally, low-grade carbide soft scrap is discarded as waste, and there is no method to recover tungsten compounds from low-grade carbide soft scrap.

[0004] Accordingly, the applicant has completed the present invention by obtaining a method for recovering high-purity tungsten compounds by physicochemical concentration from low-grade carbide soft scraps, through long-term strenuous efforts and various studies, by wet crushing and magnetically separating low-grade carbide soft scraps that are discarded as waste to recover concentrated high-purity WC-Co, and then performing a physicochemical concentration process on the recovered high-purity WC-Co to recover high-purity tungsten compounds. Prior art literature

[0006] Republic of Korea Published Patent No. 10-2017-0141313 (Published December 26, 2017) The problem to be solved

[0007] Accordingly, the objective of the present invention is to provide a method for recovering high-purity tungsten compounds by physicochemical concentration from low-grade hard carbide soft scraps, by wet crushing and magnetic separation of low-grade hard carbide soft scraps discarded as waste to recover concentrated high-purity WC-Co, and then performing a physicochemical concentration process on the recovered high-purity WC-Co to recover high-purity tungsten compounds.

[0008] In addition, the objective of the present invention is to provide tungsten, tungsten compounds, or tungsten oxide recovered with a high purity of 95 to 99.998 weight% by a method for recovering high-purity tungsten compounds from low-grade hard carbide soft scrap by physicochemical concentration.

[0009] The problems that the present invention aims to solve are not limited to those mentioned above, and other unmentioned problems will be clearly understood by those skilled in the art from the description below. means of solving the problem

[0011] In order to solve the above problem, according to one aspect of the present invention,

[0012] A step of recovering concentrated high-purity WC-Co by wet crushing and magnetic separation of low-grade hard carbide soft scrap;

[0013] A step of performing a physicochemical concentration process of oxidation, alkaline leaching, solid-liquid separation, precipitation separation, and crystallization on the recovered high-purity WC-Co; and

[0014] A step comprising recovering a physicochemically concentrated high-purity tungsten compound

[0015] A method for recovering high-purity tungsten compounds from low-grade hard carbide soft scrap by physicochemical concentration is provided.

[0016] According to one embodiment of the present invention, in the step of recovering concentrated high-purity WC-Co by wet crushing and magnetic separation of the low-grade hard carbide soft scrap,

[0017] The content of the above-mentioned concentrated WC-Co may be 60 to 90 weight%.

[0018] According to one embodiment of the present invention, in the step of recovering concentrated high-purity WC-Co by wet crushing and magnetic separation of the low-grade hard carbide soft scrap,

[0019] The above-mentioned low-grade carbide soft scrap is a process byproduct generated during the machining (grinding) of W-Co cemented carbide alloys, and consists of WC-Co grinding powder and oil.

[0020] Sludge may be generated during the process of recovering oil by passing the above-mentioned low-grade carbide soft scrap through a porous diatomite layer.

[0021] According to one embodiment of the present invention, in the step of recovering concentrated high-purity WC-Co by wet crushing and magnetic separation of the low-grade hard carbide soft scrap,

[0022] The above sludge is composed of WC-Co abrasive powder and diatomite containing residual oil, and

[0023] When the above residual oil is recovered through an oil recovery process, it can finally be discharged in the form of a mixed powder of WC-Co abrasive powder and diatomite.

[0024] According to one embodiment of the present invention, in the step of recovering concentrated high-purity WC-Co by wet crushing and magnetic separation of the low-grade hard carbide soft scrap,

[0025] The above wet grinding is

[0026] In order to improve the degree of separation of fine WC-Co particles trapped in the above porous diatomite,

[0027] You can use an attrition mill, ball mill, or vibrating mill, and

[0028] When using an attrition mill,

[0029] High-cost ratio (high / cost) 0.2 ~ 1.0 and,

[0030] It can be performed at a mill rotation speed of 250 to 2000 rpm.

[0031] According to one embodiment of the present invention, in the step of recovering concentrated high-purity WC-Co by wet crushing and magnetic separation of the low-grade hard carbide soft scrap,

[0032] In order to improve the dispersibility of the ground particles during the above wet grinding, sodium hexametaphosphate, sodium silicate, or a polymer dispersant may be used as a dispersant.

[0033] According to one embodiment of the present invention, in the step of recovering concentrated high-purity WC-Co by wet crushing and magnetic separation of the low-grade hard carbide soft scrap,

[0034] The above magnetic separation can be performed using a Wet Drum Magnetic Separator at a drum magnetic strength of 1.0 T (10,000 gauss) to 1.8 T (18,000 gauss).

[0035] According to one embodiment of the present invention, in the step of performing a physicochemical concentration process of oxidation, alkaline leaching, solid-liquid separation, precipitation separation, and crystallization on the recovered high-purity WC-Co,

[0036] The above oxidation process is in the atmosphere

[0037] A reaction temperature of 200 to 900 ℃ and,

[0038] The reaction can be performed for a reaction time of 1 to 24 hours.

[0039] According to one embodiment of the present invention, in the step of performing a physicochemical concentration process of oxidation, alkaline leaching, solid-liquid separation, precipitation separation, and crystallization on the recovered high-purity WC-Co,

[0040] The above alkali leaching process is

[0041] Using alkali compounds of sodium hydroxide, sodium chloride, potassium chloride, calcium chloride, sodium carbonate, potassium carbonate, or calcium carbonate,

[0042] It can be performed at a high-cost ratio (high / cost) of 0.1 to 1.5.

[0043] According to one embodiment of the present invention, in the step of performing a physicochemical concentration process of oxidation, alkaline leaching, solid-liquid separation, precipitation separation, and crystallization on the recovered high-purity WC-Co,

[0044] The above alkali leaching process is

[0045] In the high-cost ratio (high / cost) of 0.1 to 1.5,

[0046] Reaction temperature 40 ~ 100 ℃ and,

[0047] The reaction time can be performed for 30 minutes to 6 hours.

[0048] According to one embodiment of the present invention, in the step of performing a physicochemical concentration process of oxidation, alkaline leaching, solid-liquid separation, precipitation separation, and crystallization on the recovered high-purity WC-Co,

[0049] The above precipitation separation process is a tungsten solution purification process through the removal of impurities from the tungsten leaching solution prior to purification. and through a solvent extraction process,

[0050] The above tungsten solution purification process controls the pH to 8 to 14, then adds aluminum sulfate to co-precipitate and remove impurities, thereby obtaining a purified tungsten leaching solution.

[0051] The above solvent extraction process extracts tungsten using a tungsten extractant at a pH of 0.2 to 5 of the purified tungsten leaching solution, and the tungsten can be removed by adding sodium hydroxide, sodium carbonate, potassium carbonate, or calcium carbonate.

[0052] According to one embodiment of the present invention, in the step of performing a physicochemical concentration process of oxidation, alkaline leaching, solid-liquid separation, precipitation separation, and crystallization on the recovered high-purity WC-Co,

[0053] The above crystallization process is a process of crystallizing the removed tungsten by vacuum evaporation concentration,

[0054] Pressure 300 ~ 2000 mbar,

[0055] Evaporation temperature 30 ~ 100 ℃,

[0056] It can be performed at a stirring speed of 20 to 500 rpm.

[0057] According to one embodiment of the present invention, in the step of recovering the physicochemically concentrated high-purity tungsten compound,

[0058] The purity of the above tungsten compound may be 95 to 99.998 weight%.

[0060] In addition, according to another aspect of the present invention,

[0061] Tungsten, tungsten compounds, or tungsten oxide recovered with a high purity of 95 to 99.998 weight% by the method of recovering high-purity tungsten compounds by physicochemical concentration from the above-mentioned low-grade carbide soft scrap can be provided. Effects of the invention

[0063] According to the present invention, a method for recovering high-purity tungsten compounds by physicochemical concentration from low-grade carbide soft scrap is provided, wherein high-purity WC-Co is recovered by wet crushing and magnetic separation of low-grade carbide soft scrap discarded as waste, and then a physicochemical concentration process is performed on the recovered high-purity WC-Co to recover high-purity tungsten compounds. This method offers excellent process stability and is economical as it enables mass production.

[0064] In addition, the present invention provides tungsten, tungsten compounds, or tungsten oxide recovered with a high purity of 95 to 99.998 weight% by a method for recovering high-purity tungsten compounds from low-grade carbide soft scrap by physicochemical concentration, so that the physical properties are excellent and commercially viable.

[0065] The effects of the present invention are not limited to the effects described above, and should be understood to include all effects that can be inferred from the configuration of the invention described in the detailed description of the invention or the claims. Brief explanation of the drawing

[0067] FIG. 1 is a process flow diagram of a method for recovering high-purity tungsten compounds by physicochemical concentration from low-grade hard carbide soft scrap according to one embodiment of the present invention. FIG. 2 is a schematic diagram of a process for recovering a high-purity tungsten compound by physicochemical concentration from low-grade hard carbide soft scrap according to one embodiment of the present invention. Figure 3 is a graph of the removal rate of oil and moisture according to temperature of low-grade carbide soft scrap according to one embodiment of the present invention. Figure 4 is a graph of the amount of magnetic product produced according to grinding time with and without the use of a dispersant, according to one embodiment of the present invention. Figure 5 is a graph of the XRD analysis results (a) before oxidation and (b) after oxidation according to one embodiment of the present invention. FIG. 6 is a graph showing the change in tungsten leaching rate according to (a) reaction time and (b) NaOH content according to one embodiment of the present invention. FIG. 7 is a graph showing the change in tungsten leaching rate according to (a) solid-liquid ratio and (b) reaction temperature according to one embodiment of the present invention. FIG. 8 is a photograph of a silica cake separated in a tungsten leaching solution purification process according to one embodiment of the present invention. Figure 9 is an XRD analysis graph of Na2WO4 powder recovered through a crystallization process according to one embodiment of the present invention, and (b) a photograph of Na2WO4 powder recovered through a crystallization process. FIG. 10 is a photograph of Na2WO4 powder recovered from WC-Co soft scrap, which is the final recovered product according to one embodiment of the present invention. Specific details for implementing the invention

[0068] Preferred embodiments according to the present invention will be described in detail below with reference to the attached drawings.

[0069] The advantages and features of the present invention and the method for achieving them will become clear by referring to the embodiments described in detail below together with the accompanying drawings.

[0070] However, the present invention is not limited by the embodiments disclosed below but may be implemented in various different forms, and these embodiments are provided merely to make the disclosure of the present invention complete and to fully inform those skilled in the art of the scope of the invention, and the present invention is defined only by the scope of the claims.

[0071] In addition, in describing the present invention, if it is determined that related known technologies, etc., may obscure the essence of the present invention, a detailed explanation thereof will be omitted.

[0072] The present invention will be described in detail below.

[0074] Method for recovering high-purity tungsten compounds from low-grade hard carbide soft scrap by physicochemical concentration

[0075] The present invention provides a method for recovering high-purity tungsten compounds by physicochemical concentration from low-grade hard carbide soft scrap, wherein high-purity WC-Co is recovered by wet crushing and magnetic separation of low-grade hard carbide soft scrap discarded as waste, and then high-purity tungsten compounds are recovered by performing a physicochemical concentration process on the recovered high-purity WC-Co.

[0076] The method for recovering high-purity tungsten compounds from low-grade hard carbide soft scrap by physicochemical concentration according to the present invention is,

[0077] A step of recovering concentrated high-purity WC-Co by wet crushing and magnetic separation of low-grade hard carbide soft scrap;

[0078] A step of performing a physicochemical concentration process of oxidation, alkaline leaching, solid-liquid separation, precipitation separation, and crystallization on the recovered high-purity WC-Co; and

[0079] It includes the step of recovering a physicochemically concentrated high-purity tungsten compound.

[0080] The present invention provides a method for recovering high-purity tungsten compounds by physicochemical concentration from low-grade hard carbide soft scrap, in which high-purity WC-Co is recovered by wet crushing and magnetic separation of low-grade hard carbide soft scrap discarded as waste, and then high-purity tungsten compounds are recovered by performing a physicochemical concentration process on the recovered high-purity WC-Co. This method offers excellent process stability and is economical as it enables mass production.

[0082] Generally, low-grade carbide soft scrap is discarded as waste, and there is no method to recover tungsten compounds from low-grade carbide soft scrap.

[0083] Accordingly, the applicant has completed the present invention by obtaining a method for recovering high-purity tungsten compounds by physicochemical concentration from low-grade carbide soft scraps, through long-term strenuous efforts and various studies, by wet crushing and magnetically separating low-grade carbide soft scraps that are discarded as waste to recover concentrated high-purity WC-Co, and then performing a physicochemical concentration process on the recovered high-purity WC-Co to recover high-purity tungsten compounds.

[0085] Here, the present invention may be a method for recovering a high-purity tungsten compound by physicochemical concentration from low-grade carbide soft scrap, wherein high-purity WC-Co is recovered by wet crushing and magnetic separation of low-grade carbide soft scrap discarded as waste, and then a physicochemical concentration process is performed on the recovered high-purity WC-Co to recover a high-purity tungsten compound.

[0086] At this time, in the step of recovering concentrated high-purity WC-Co by wet crushing and magnetic separation of the low-grade carbide soft scrap,

[0087] The content of the above-mentioned concentrated WC-Co may be 60 to 90 weight%.

[0088] In addition, in the step of recovering concentrated high-purity WC-Co by wet crushing and magnetic separation of the above-mentioned low-grade carbide soft scrap,

[0089] The above-mentioned low-grade carbide soft scrap is a process byproduct generated during the machining (grinding) of W-Co cemented carbide alloys, and consists of WC-Co grinding powder and oil.

[0090] Sludge may be generated during the process of recovering oil by passing the above-mentioned low-grade carbide soft scrap through a porous diatomite layer.

[0091] Here, in the step of recovering concentrated high-purity WC-Co by wet crushing and magnetic separation of the low-grade carbide soft scrap,

[0092] The above sludge is composed of WC-Co abrasive powder and diatomite containing residual oil, and

[0093] When the above residual oil is recovered through an oil recovery process, it can finally be discharged in the form of a mixed powder of WC-Co abrasive powder and diatomite.

[0094] And, in the step of recovering concentrated high-purity WC-Co by wet crushing and magnetic separation of the above-mentioned low-grade carbide soft scrap,

[0095] The above wet grinding is

[0096] In order to improve the degree of separation of fine WC-Co particles trapped in the above porous diatomite,

[0097] You can use an attrition mill, ball mill, or vibrating mill, and

[0098] When using an attrition mill,

[0099] High-cost ratio (high / cost) 0.2 ~ 1.0 and,

[0100] It can be performed at a mill rotation speed of 250 to 2000 rpm.

[0101] Here, if the above solid-liquid ratio is within the above range, the degree of separation of fine WC-Co particles trapped in the porous diatomite can be improved.

[0102] At this time, the above high-to-lower ratio may preferably be 0.2 to 0.95, and more preferably 0.2 to 0.9.

[0103] In addition, if the mill rotation speed is within the above range, the degree of separation of fine WC-Co particles trapped in the porous diatomite can be improved.

[0104] At this time, the mill rotation speed may preferably be 250 to 1950 rpm, and more preferably 250 to 1900 rpm.

[0105] And, in the step of recovering concentrated high-purity WC-Co by wet crushing and magnetic separation of the above-mentioned low-grade carbide soft scrap,

[0106] In order to improve the dispersibility of the ground particles during the above wet grinding, sodium hexametaphosphate, sodium silicate, or a polymer dispersant may be used as a dispersant.

[0107] In addition, in the step of recovering concentrated high-purity WC-Co by wet crushing and magnetic separation of the above-mentioned low-grade carbide soft scrap,

[0108] The above magnetic separation can be performed using a Wet Drum Magnetic Separator at a drum magnetic strength of 1.0 T (10,000 gauss) to 1.8 T (18,000 gauss).

[0109] Here, if the Drum magnetic strength is within the above range, the concentrated high-purity WC-Co can be recovered.

[0110] At this time, the Drum magnetic force strength may preferably be 1.0 T (10,000 gauss) to 1.45 T (14,500 gauss), and more preferably 1.0 T (10,000 gauss) to 1.4 T (14,000 gauss).

[0111] And, in the step of performing physicochemical concentration processes of oxidation, alkaline leaching, solid-liquid separation, precipitation separation, and crystallization on the recovered high-purity WC-Co,

[0112] The above oxidation process is in the atmosphere

[0113] A reaction temperature of 200 to 900 ℃ and,

[0114] The reaction can be performed for a reaction time of 1 to 24 hours.

[0115] Here, if the reaction temperature is within the above range, the oxidation process can be performed excellently.

[0116] At this time, the reaction temperature may preferably be 250 to 800 ℃, and more preferably 300 to 700 ℃.

[0117] In addition, if the reaction time is within the above range, the oxidation process can be performed excellently.

[0118] At this time, the reaction time may preferably be 1 to 20 hours, and more preferably 2 to 12 hours.

[0119] And, in the step of performing physicochemical concentration processes of oxidation, alkaline leaching, solid-liquid separation, precipitation separation, and crystallization on the recovered high-purity WC-Co,

[0120] The above alkali leaching process is

[0121] Using alkali compounds of sodium hydroxide, sodium chloride, potassium chloride, calcium chloride, sodium carbonate, potassium carbonate, or calcium carbonate,

[0122] It can be performed at a high-cost ratio (high / cost) of 0.1 to 1.5.

[0123] Here, if the above high-to-liquid ratio is within the above range, the alkali leaching process can be performed excellently.

[0124] At this time, the above high-to-lower ratio may preferably be 0.1 to 1.45, and more preferably 0.1 to 1.40.

[0125] In addition, in the step of performing physicochemical concentration processes of oxidation, alkaline leaching, solid-liquid separation, precipitation separation, and crystallization on the recovered high-purity WC-Co,

[0126] The above alkaline leaching process is

[0127] In the high-cost ratio (high / cost) of 0.1 to 1.5,

[0128] Reaction temperature 40 ~ 100 ℃ and,

[0129] The reaction time can be performed for 30 minutes to 6 hours.

[0130] Here, if the above high-to-liquid ratio is within the above range, the alkali leaching process can be performed excellently.

[0131] At this time, the above high-to-lower ratio may preferably be 0.1 to 1.45, and more preferably 0.1 to 1.40.

[0132] And, if the reaction temperature is within the above range, the alkali leaching process can be performed excellently.

[0133] At this time, the reaction temperature may preferably be 40 to 98 ℃, and more preferably 40 to 95 ℃.

[0134] In addition, if the reaction time is within the above range, the alkali leaching process can be performed excellently.

[0135] At this time, the reaction time may preferably be 1 to 4 hours, and more preferably 1 to 3 hours.

[0136] And, in the step of performing physicochemical concentration processes of oxidation, alkaline leaching, solid-liquid separation, precipitation separation, and crystallization on the recovered high-purity WC-Co,

[0137] The above precipitation separation process is a tungsten solution purification process through the removal of impurities from the tungsten leaching solution prior to purification. and through a solvent extraction process,

[0138] The above tungsten solution purification process controls the pH to 8 to 14, then adds aluminum sulfate to co-precipitate and remove impurities, thereby obtaining a purified tungsten leaching solution.

[0139] The above solvent extraction process extracts tungsten using a tungsten extractant at a pH of 0.2 to 5 of the purified tungsten leaching solution, and the tungsten can be removed by adding sodium hydroxide, sodium carbonate, potassium carbonate, or calcium carbonate.

[0140] That is, the above tungsten solution purification process removes Si, a major impurity, at pH = 8 to 14, and removes the Si remaining in the solution by adding aluminum sulfate to co-precipitate the impurities, thereby obtaining a purified tungsten leaching solution.

[0141] Tungsten can be extracted from the above purified leaching solution using a tungsten extractant at a pH of 0.2 to 5, and the tungsten can be removed by adding sodium hydroxide, sodium carbonate, potassium carbonate, or calcium carbonate.

[0142] Here, if the pH range of the tungsten solution purification process is within the above range, the purification of the tungsten solution can be performed excellently.

[0143] At this time, the pH of the tungsten solution purification process may preferably be 8 to 13.5, and more preferably 8 to 13.

[0144] In addition, if the tungsten solvent extraction pH in the tungsten leaching solution is within the above range, tungsten extraction can be performed excellently.

[0145] At this time, the tungsten solvent extraction pH in the tungsten leaching solution may preferably be 0.2 to 4.5, and more preferably 0.2 to 4.

[0146] In addition, if the pH of the tungsten removal solution is within the range of 7 to 9, tungsten removal can be performed excellently.

[0147] And, in the step of performing physicochemical concentration processes of oxidation, alkaline leaching, solid-liquid separation, precipitation separation, and crystallization on the recovered high-purity WC-Co,

[0148] The above crystallization process is a process of crystallizing the removed tungsten by vacuum evaporation concentration,

[0149] Pressure 300 ~ 2000 mbar,

[0150] Evaporation temperature 30 ~ 100 ℃,

[0151] It can be performed at a stirring speed of 20 to 500 rpm.

[0152] Here, when the pressure is within the above range, the process of crystallizing the removed tungsten by vacuum evaporation concentration can be performed excellently.

[0153] At this time, the pressure may preferably be 300 to 1950 mbar, and more preferably 300 to 1900 mbar.

[0154] In addition, if the above evaporation temperature is within the above range, the process of crystallizing the removed tungsten by vacuum evaporation concentration can be performed excellently.

[0155] At this time, the evaporation temperature may preferably be 30 to 98 ℃, and more preferably 30 to 95 ℃.

[0156] And, when the stirring speed is within the above range, the process of crystallizing the removed tungsten by vacuum evaporation concentration can be performed excellently.

[0157] At this time, the stirring speed may preferably be 20 to 480 rpm, and more preferably 20 to 450 rpm.

[0158] In addition, in the step of recovering the physicochemically concentrated high-purity tungsten compound,

[0159] The purity of the above tungsten compound may be 95 to 99.998 weight%.

[0161] FIG. 1 is a process flow diagram of a method for recovering high-purity tungsten compounds by physicochemical concentration from low-grade hard carbide soft scrap according to one embodiment of the present invention.

[0162] Referring to FIG. 1, first, low-grade carbide soft scrap is wet-crushed and magnetically separated to recover concentrated high-purity WC-Co (S110).

[0163] After that, physicochemical concentration processes of oxidation, alkaline leaching, solid-liquid separation, precipitation separation, and crystallization are performed on the recovered high-purity WC-Co (S120).

[0164] Then, a physicochemically concentrated high-purity tungsten compound is recovered (S130).

[0166] FIG. 2 is a schematic diagram of a process for recovering a high-purity tungsten compound by physicochemical concentration from low-grade hard carbide soft scrap according to one embodiment of the present invention.

[0167] Referring to FIG. 2, a pretreatment process is first performed to remove oil and residual moisture from low-grade carbide soft scrap to recover WC-Co sludge (S210).

[0168] After that, an oxidation process is performed on the recovered WC-Co sludge (S220), followed by alkaline leaching (S240) and then solid-liquid separation (S260).

[0169] Then, an alkali compound is added to the WC-Co sludge (S230), followed by water leaching (S250), and then solid-liquid separation is performed to recover the tungsten-containing solution (S260).

[0170] Then, the tungsten-containing solution is precipitated and purified to recover the tungsten compound solution (S270).

[0171] After that, the tungsten compound solution is crystallized to recover a high-purity tungsten compound (S280).

[0173] High-purity recovered tungsten, tungsten compounds, or tungsten oxide

[0174] The present invention provides tungsten, tungsten compounds, or tungsten oxide recovered with a high purity of 95 to 99.998 weight% by a method for recovering high-purity tungsten compounds from low-grade carbide soft scrap by physicochemical concentration.

[0175] The present invention provides tungsten, tungsten compounds, or tungsten oxide recovered with a high purity of 95 to 99.998 weight% by a method for recovering high-purity tungsten compounds from low-grade hard carbide soft scrap by physicochemical concentration, so that the physical properties are excellent and commercially viable.

[0177] The present invention will be explained in more detail below through examples. However, the following examples are intended to explain the invention more specifically and do not limit the scope of the invention. The following examples may be appropriately modified or changed by those skilled in the art within the scope of the invention.

[0179] <Example>

[0180] <Examples 1–4> Removal of oil and moisture in the high-purity WC-Co recovery process

[0181] Low-grade carbide soft scrap and high-grade carbide soft scrap obtained from DaeguTec were subjected to a high-temperature evaporation process for 6 hours at the reaction temperatures shown in Table 1 and Figure 3 below to remove oil and residual moisture. The removal rate of oil and residual moisture was confirmed by measuring the weight change after 6 hours of heat treatment.

[0183] Example 1 Example 2 Example 3 Example 4 Reaction temperature (°C) 150 200 250 300 Removal rate of oil and residual moisture (weight%) High quality 0.9 1.9 9.5 10.2 low quality 2.3 5.5 40.1 42.0

[0185] Figure 3 is a graph of the removal rate of oil and moisture according to temperature of low-grade hard carbide soft scrap according to Examples 1 to 4 above.

[0186] Referring to Table 1 and Figure 3 above, the removal rate of oil and residual moisture according to temperature was significantly higher for low-grade carbide soft scrap than for high-grade carbide soft scrap.

[0188] <Examples 5–10> Wet Grinding and Magnetic Separation Using a Dispersant in a High-Purity WC-Co Recovery Process

[0189] The above Example 1, from which oil and residual moisture had been removed, was wet-milled using an internal volume 1 L attrition mill, with a solid-liquid ratio of 0.4 (100 g sludge + 250 ml water) and a mill rotation speed of 500 rpm, using sodium hexametaphosphate (0.5 wt%) as a dispersant to improve the dispersibility of the ground particles, for the milling times shown in Table 2 and Figure 4 below.

[0190] Afterwards, WC-Co with a content of 29–48 wt% was recovered by magnetic separation using a Wet Drum Magnetic Separator at a drum magnetic strength of 1.0–1.4 T.

[0192] <Comparative Examples 1 to 3> Wet Grinding and Magnetic Separation Without Dispersant in High-Purity WC-Co Recovery Process

[0193] As shown in Table 2 below, WC-Co with a content of 36-42 wt% was recovered by wet grinding and magnetic separation in the same manner as Example 8, except that no dispersant was used during the grinding time and wet grinding was performed.

[0195] Example 5 Example 6 Example 7 Example 8 Example 9 Example 10 Comparative Example 1 Comparative Example 2 Comparative Example 3 Grinding time (minutes) 0 1 3 5 10 20 5 10 20 Dispersant sodium hexametaphosphate sodium hexametaphosphate sodium hexametaphosphate sodium hexametaphosphate sodium hexametaphosphate sodium hexametaphosphate - - - Magnetic force (T) 1.0 1.0 1.2 1.0 1.2 1.4 1.0 1.2 1.4 Magnetic product yield (weight%) 48.3 43.1 34.2 33.3 32.1 29.1 40.9 35.7 42.0 WC-Co Purity (Weight%) 59.6 70.4 86.7 88.7 90.1 90.0 66.4 70.8 54.4

[0197] Figure 4 is a graph of the amount of magnetic product produced according to grinding time when a dispersant is used and when a dispersant is not used, according to Examples 5 to 10 above.

[0198] Referring to Table 2 and Figure 4 above, Examples 5 to 10 using a dispersant had a slightly lower yield of magnetic product than Comparative Examples 1 to 3 not using a dispersant, but had excellent dispersibility, which was advantageous for subsequent processes.

[0200] In addition, the purity of the WC-Co sludge according to Examples 5 to 10 was 60 to 90 weight%, and the content of the WC-Co sludge according to Comparative Examples 1 to 3 was 54 to 71 weight%.

[0202] <Example 11> Oxidation process on recovered WC-Co sludge

[0203] The WC-Co sludge recovered in Example 8 above was subjected to an oxidation process in air at 600 °C for 3 hours to produce WO x / Co x Recovered.

[0205] Figure 5 is a graph of the XRD analysis results (a) before oxidation and (b) after oxidation according to Example 11 above.

[0206] Referring to Figures 5a and 5b, XRD analysis results after oxidation confirmed that tungsten was oxidized to WO3 or CoWO4 compared to before oxidation.

[0208] <Examples 12–18> Alkaline leaching process of WOx / Cox after oxidation process according to reaction temperature

[0209] WO recovered in Example 11 above x / Co x An alkaline leaching process was performed at a reaction time as shown in Table 3 and Fig. 6a below, with 20 wt% of sodium hydroxide added, at a solid-liquid ratio of 0.2 and a reaction temperature of 80 ℃.

[0211] Example 12 Example 13 Example 14 Example 15 Example 16 Example 17 Example 18 Reaction time (time) 0.5 1 1.5 2 3 4 6 Tungsten leaching efficiency (%) High quality 73 86 93 98 99.7 99.8 99.9 low quality 69 93 99.8 99.9 99.9 99.9 99.9

[0213] FIG. 6a is a graph showing the change in tungsten leaching rate according to reaction time in Examples 12 to 18 above.

[0214] Referring to Table 3 and Fig. 6a above, it was confirmed that the tungsten leaching efficiency of Examples 12 to 18 was 69 to 99.9%.

[0215] In addition, during the alkaline leaching of Examples 12 to 18 above, the cobalt leaching rate was 1 to 1.5%.

[0217] <Examples 19 ~ 22> Alkaline leaching process of WOx / Cox after oxidation process according to sodium hydroxide concentration

[0218] WO recovered in Example 11 above x / Co x An alkaline leaching process was carried out for 2 hours at a reaction time of 2 hours at a solid-liquid ratio of 0.5 and a reaction temperature of 80 ℃ at sodium hydroxide concentrations as shown in Table 4 and Fig. 6b below.

[0220] Example 19 Example 20 Example 21 Example 22 Sodium hydroxide concentration (weight%) 5 10 15 20 Tungsten leaching efficiency (%) 42 52 53 88

[0222] FIG. 6b is a graph showing the change in tungsten leaching rate according to sodium hydroxide concentration in Examples 19 to 22 above.

[0223] Referring to Table 4 and Fig. 6b above, it was confirmed that the tungsten leaching efficiency of Examples 19 to 22 was 42 to 88%.

[0224] In addition, during the alkaline leaching of Examples 19 to 22 above, the cobalt leaching rate was 1% or less.

[0226] <Examples 23 ~ 26> Tungsten leaching process according to solid-liquid ratio

[0227] After the alkaline leaching process of Example 16 above, a leaching process was performed at a solid-liquid ratio as shown in Table 5 and Figure 7a below to recover the tungsten leaching solution.

[0229] Example 23 Example 24 Example 25 Example 26 High cost (w / w) 0.1 0.2 0.4 0.5 Tungsten leaching efficiency (%) 99.9 93 90 87

[0231] FIG. 7a is a graph showing the change in tungsten leaching rate according to the solid-liquid ratio in Examples 23 to 26 above.

[0232] Referring to Table 5 and Fig. 7a above, it was confirmed that the tungsten leaching efficiency of Examples 23 to 26 was 87 to 99.9%.

[0233] In addition, during solid-liquid separation in Examples 23 to 26 above, the cobalt leaching rate was 1% or less.

[0235] <Examples 27 ~ 30> Tungsten Leaching Behavior According to Reaction Temperature of Alkaline Leaching Process

[0236] After the alkaline leaching process of Example 16 above, a leaching process was performed at a reaction temperature as shown in Table 6 and Fig. 7b below to recover the tungsten leaching solution and determine the tungsten leaching behavior.

[0238] Example 27 Example 28 Example 29 Example 30 Reaction temperature (°C) 20 40 60 80 Tungsten leaching efficiency (%) 29 53 62 88

[0240] FIG. 7b is a graph showing the change in tungsten leaching rate according to the reaction temperature in Examples 27 to 30 above.

[0241] Referring to Table 6 and Fig. 7b above, it was confirmed that the tungsten leaching efficiency of Examples 27 to 30 was 29 to 88%.

[0242] In addition, during solid-liquid separation in Examples 27 to 30 above, the cobalt leaching rate was 0.1% or less.

[0244] <Example 31> Purification of Tungsten Solution After Leaching Process

[0245] Si was precipitated from the tungsten leaching solution of Example 30 and purified to recover the tungsten solution.

[0246] Table 7 below shows the chemical composition results of the tungsten leaching solution of Example 30 at pH 13.2 analyzed by ICP-OES.

[0248] element W Si Fe Cr Mg Ni Mo Ca Concentration (mg / L) 81 g / L 23 g / L 68 44 34 22 11 9

[0250] Referring to Table 7 above, the tungsten leaching solution of 30 in the above example contained an excess amount of Si.

[0252] In addition, Table 8 below shows the results of analyzing the Si component of the tungsten leaching solution of Example 30 at various pH values ​​using ICP-OES.

[0254] pH Initial (13.2) 12 11 10 9 8.5 Si concentration (mg / L) 23,100 22,910 20,170 17,100 144.8 139.2

[0256] Referring to Table 8 above, it was confirmed that if the pH of the tungsten leaching solution of Example 30 is adjusted to 9 or lower, the concentration of Si can be maintained at less than 1 g / L.

[0258] And, Table 9 below shows the chemical composition results analyzed by ICP-OES after adjusting the pH of the tungsten leaching solution of Example 30 to 9 or lower and adding aluminum sulfate.

[0260] element W Si Fe Cr Mg Ni Mo Ca Concentration (mg / L) 81.5 g / L < 1 4 2 ND ND 10 ND

[0261] Here, ND indicates no detection.

[0263] Referring to Table 9 above, it was confirmed that the pH of the tungsten leaching solution of Example 30 was adjusted to 9 or lower, and after adding aluminum sulfate, the Si concentration was maintained at less than 1 mg / L.

[0264] In addition, the pH of the tungsten leaching solution of Example 30 was adjusted to 9 or lower, aluminum sulfate was added, the Si concentration was maintained at less than 1 mg / L, and elements other than tungsten were removed by co-precipitation.

[0266] Figure 8 is a photograph of a silica cake separated in the tungsten leaching solution purification process according to Example 31 above.

[0267] Referring to Fig. 8, the silica cake has a slow filtration rate and a high water content of about 60 wt%, which causes a loss of tungsten solution.

[0269] <Example 32> Solvent extraction after tungsten solution purification process

[0270] After the purification process of the tungsten solution in Example 31 above, the tungsten compound solution was solvent extracted.

[0271] Table 10 below shows the solvent extraction process conditions of Example 32 above.

[0273] Mixing ratio(Vol.) Alamine336:isodecanol:D80=1:1:8 Number of stages Extraction 2 Stripping 2 O / A ratio Extraction 2 Stripping 1 Temperature, C 40 Tungsten leaching solution (pH 14) Flow Countercurrent exchange flow

[0275] In addition, Table 11 below shows the tungsten extraction rate results according to the pH of the raw material solution (aqueous solution).

[0277] Initial pH 0.5 1 2 3 Extraction efficiency (%) 97.7 ≥99.9 ≥99.9 86.3

[0279] Referring to Table 11 above, when the initial pH was 1 to 2, the extraction efficiency was 99.9% or higher.

[0281] And, Table 12 below shows the tungsten removal efficiency results according to the removal solution concentration (Na2CO3 solution Conc.).

[0283] [Na2CO3], weight% 15 20 25 30 Stripping efficiency (%) 82.2 99.1 99.4 99.5

[0285] Referring to Table 12 above, when the removal solution concentration (Na2CO3 solution Conc.) was 20 wt% or more, the tungsten removal efficiency was 99% or more.

[0287] In addition, Table 13 below shows the results of chemical analysis of the solution after solvent extraction from the raw material.

[0289] Element W Si Fe Cr Mg Ni Mo Ca Conc., mg / L Feed 1 814 234 68 44 34 22 11 9 Treated 2 81.54 ≤1 4 2 ND ND 10 ND SX 3 12.25 ND ND ND NA NA 88 NA

[0290] 1. Tungsten leaching solution (pH 14)

[0291] 2. pH control + Al2(SO4)3addition (Al / Si=1.1)

[0292] 3. Centrifugal solvent extractor ([P] = 14 mg / L [S] = 44 mg / L, XRF analysis)

[0293] 4. Unit: g / L

[0294] 5. Unit: %

[0295] ND: Not detected, NA: Not applicable

[0297] Referring to Table 13 above, after solution purification, the tungsten recovery rate was 95.1 wt%, and 98.3 wt% when excluding losses due to Si cake moisture content.

[0299] <Example 33> Crystallization of tungsten compound solution after solvent extraction

[0300] After solvent extraction of the tungsten compound solution of Example 32 above, the tungsten compound solution was crystallized to recover a high-purity tungsten compound.

[0302] Table 14 below shows the vacuum evaporation concentration crystallization process conditions of Example 33 above.

[0304] Temperature, °C 90 Pressure, mbar 700 Agitation, rpm 40 Vol. of feed, mL 1500 Evaporation degree, Vol.% 50 / 60 / 70(±5)

[0306] Table 15 below shows the results of the ICP-OES chemical analysis of the raw materials for the vacuum evaporation crystallization process.

[0308] Element W Mo P S Conc., mg / L 12.2 (weight%) 88 14 44

[0310] Referring to Table 15 above, the concentration of tungsten in the raw material of the vacuum evaporation crystallization process was 12.2 wt%.

[0312] Figure 9 is an XRD analysis graph of Na2WO4 powder recovered through the crystallization process according to Example 33 above, (a) and a photograph of Na2WO4 powder recovered through the crystallization process.

[0313] Referring to Fig. 9a, the XRD graph confirmed that the powder recovered through the crystallization process was Na2WO4 powder.

[0314] Referring to Fig. 9b, the Na2WO4 powder recovered through the crystallization process was a white powder.

[0316] In addition, Table 16 below shows the results of the chemical analysis of the final recovered tungsten compound.

[0317] Composition W(%) P S Mo Ca Content (Weight%) 61.5 1 97 61 4 ND

[0318] 1. Based on Na2WO4: 98.57 wt% (77.8 wt% as WO3)

[0320] That is, as a result of chemical analysis of Na2WO4 powder, 98.57 wt% (WO3=77.8 wt%) based on Na2WO4 was recovered.

[0322] Figure 10 is a photograph of Na2WO4 powder recovered from WC-Co soft scrap, which is the final recovered product according to Example 33 above.

[0323] Referring to Fig. 10, the Na2WO4 powder recovered from the final recovered product, WC-Co soft scrap, was a white powder.

[0324] And, as a result of chemical analysis of the Na2WO4 powder, it was recovered at 99.91 wt% based on Na2WO4 (WO3=78.83 wt%).

[0326] Although specific embodiments regarding the method for recovering high-purity tungsten compounds by physicochemical concentration from low-grade hard carbide soft scrap according to the present invention have been described so far, it is obvious that various modifications are possible within the scope of the present invention.

[0327] Therefore, the scope of the present invention should not be limited to the described embodiments, but should be defined by the claims set forth below as well as equivalents thereof.

[0328] That is, the aforementioned embodiments should be understood as exemplary in all respects and not limiting, and the scope of the invention is defined by the claims set forth below rather than by the detailed description, and all modifications or variations derived from the meaning and scope of the claims and equivalent concepts thereof should be interpreted as being included within the scope of the invention.

Claims

Claim 1 A step of recovering concentrated high-purity WC-Co by wet grinding and magnetic separation of low-grade hard carbide soft scrap; a step of performing a physicochemical concentration process of oxidation, alkaline leaching, solid-liquid separation, precipitation separation, and crystallization on the recovered high-purity WC-Co; A method for recovering a high-purity tungsten compound by physicochemical concentration from low-grade hard carbide soft scrap, comprising the step of recovering a physicochemically concentrated high-purity tungsten compound, wherein the precipitation separation process comprises a tungsten solution purification process and a solvent extraction process through the removal of impurities from a tungsten leaching solution prior to purification, wherein the tungsten solution purification process controls the pH to 8 to 14, then adds aluminum sulfate to co-precipitate and remove impurities to obtain a purified tungsten leaching solution, and the solvent extraction process extracts tungsten using a tungsten extractant at a pH of 0.2 to 5 of the purified tungsten leaching solution, and removes tungsten by adding sodium hydroxide, sodium carbonate, potassium carbonate, or calcium carbonate. Claim 2 A method for recovering a high-purity tungsten compound by physicochemical concentration from low-grade hard carbide soft scrap, characterized in that, in the step of recovering concentrated high-purity WC-Co by wet grinding and magnetic separation of the low-grade hard carbide soft scrap, the content of the concentrated WC-Co is 60 to 90 weight%. Claim 3 A method for recovering a high-purity tungsten compound by physicochemical concentration from low-grade cemented carbide soft scrap, characterized in that, in the step of recovering concentrated high-purity WC-Co by wet crushing and magnetic separation of the low-grade cemented carbide soft scrap, the low-grade cemented carbide soft scrap is composed of WC-Co polishing powder and oil as a process by-product generated during the processing (polishing) of W-Co cemented carbide alloy, and sludge is generated during the process of recovering the oil by passing the low-grade cemented carbide soft scrap through a porous diatomaceous earth layer. Claim 4 A method for recovering a high-purity tungsten compound by physicochemical concentration from low-grade carbide soft scrap, characterized in that, in the step of recovering concentrated high-purity WC-Co by wet grinding and magnetic separation of the low-grade carbide soft scrap, the sludge is composed of porous diatomite containing WC-Co abrasive powder and residual oil, and when the residual oil is recovered through an oil recovery process, it is finally discharged in the form of a mixed powder of WC-Co abrasive powder and porous diatomite. Claim 5 A method for recovering a high-purity tungsten compound by physicochemical concentration from low-grade carbide soft scrap, wherein, in the step of recovering concentrated high-purity WC-Co by wet grinding and magnetic separation of the low-grade carbide soft scrap, the wet grinding is performed using an attrition mill, a ball mill, or a vibrating mill to improve the degree of separation of fine WC-Co particles trapped in the porous diatomite, and when using an attrition mill, the grinding is performed at a solid-liquid ratio (solid / liquid) of 0.2 to 1.0 and a mill rotation speed of 250 to 2000 rpm. Claim 6 A method for recovering a high-purity tungsten compound by physicochemical concentration from low-grade carbide soft scrap, characterized in that, in the step of recovering concentrated high-purity WC-Co by wet grinding and magnetic separation of the low-grade carbide soft scrap, sodium hexametaphosphate, sodium silicate, or a polymer dispersant is used as a dispersant to improve the dispersibility of the ground particles during wet grinding. Claim 7 A method for recovering a high-purity tungsten compound by physicochemical concentration from low-grade carbide soft scrap, characterized in that, in the step of recovering concentrated high-purity WC-Co by wet crushing and magnetic separation of the low-grade carbide soft scrap, the magnetic separation is performed using a Wet Drum Magnetic Separator at a drum magnetic strength of 1.0 T (10,000 gauss) to 1.8 T (18,000 gauss). Claim 8 A method for recovering a high-purity tungsten compound by physicochemical concentration from low-grade hard carbide soft scrap, wherein, in the step of performing a physicochemical concentration process of oxidation, alkaline leaching, solid-liquid separation, precipitation separation, and crystallization on the recovered high-purity WC-Co, the oxidation process is performed in the atmosphere at a reaction temperature of 200 to 900 ℃ and a reaction time of 1 to 24 hours. Claim 9 A method for recovering a high-purity tungsten compound by physicochemical concentration from low-grade hard carbide soft scrap, wherein, in the step of performing a physicochemical concentration process of oxidation, alkaline leaching, solid-liquid separation, precipitation separation, and crystallization on the recovered high-purity WC-Co, the alkaline leaching process is performed using an alkaline compound of sodium hydroxide, sodium chloride, potassium chloride, calcium chloride, sodium carbonate, potassium carbonate, or calcium carbonate at a solid-liquid ratio (solid / liquid) of 0.1 to 1.

5. Claim 10 A method for recovering a high-purity tungsten compound by physicochemical concentration from low-grade hard carbide soft scrap, wherein, in the step of performing a physicochemical concentration process of oxidation, alkaline leaching, solid-liquid separation, precipitation separation, and crystallization on the recovered high-purity WC-Co, the alkaline leaching process is performed at a solid-liquid ratio (solid / liquid) of 0.1 to 1.5, a reaction temperature of 40 to 100 ℃, and a reaction time of 30 minutes to 6 hours. Claim 11 delete Claim 12 A method for recovering a high-purity tungsten compound by physicochemical concentration from low-grade hard carbide soft scrap, wherein, in the step of performing a physicochemical concentration process of oxidation, alkaline leaching, solid-liquid separation, precipitation separation, and crystallization on the recovered high-purity WC-Co, the crystallization process is a process of crystallizing the removed tungsten by vacuum evaporation concentration, and is performed at a pressure of 300 to 2000 mbar, an evaporation temperature of 30 to 100 ℃, and a stirring speed of 20 to 500 rpm. Claim 13 A method for recovering a high-purity tungsten compound by physicochemical concentration from low-grade hard carbide soft scrap, characterized in that, in the step of recovering the physicochemically concentrated high-purity tungsten compound, the purity of the tungsten compound is 95 to 99.998 weight%. Claim 14 Tungsten, tungsten compounds, or tungsten oxide recovered with a high purity of 95 to 99.998 weight% by the method for recovering high-purity tungsten compounds by physicochemical concentration from low-grade hard carbide soft scrap according to claim 1.

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