A method for separating tungsten and cobalt from cemented carbide grinding stock

Abstract

The application belongs to the field of waste hard alloy recycling and recovery, and particularly relates to a tungsten-cobalt separation method for hard alloy grinding material, which comprises the following steps: obtaining the grinding material, mixing the grinding material with alkali to prepare a slurry for saponification reaction, and filtering to obtain a first filtrate and a first filter residue; drying and crushing the first filter residue, performing ultrasonic cleaning, and filtering to obtain a second filtrate and a second filter residue; mixing the second filter residue with a first acid solution, then adding an oxidizing agent to dissolve cobalt, and filtering to obtain a cobalt salt solution and a third filter residue, wherein the third filter residue comprises tungsten carbide. The separation method can improve the dissolution rate of cobalt after acid leaching of the grinding material, reduce the amount of reagents used in tungsten-cobalt separation, accelerate the reaction process of tungsten-cobalt separation, and obtain clean and easily recycled hard alloy grinding material; the wastewater generated in the process can be recycled, and no toxic and harmful gas is generated, which takes into account high efficiency and environmental protection.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of waste hard alloy recycling, and particularly relates to a tungsten-cobalt separation method for hard alloy grinding material. BACKGROUND

[0002] The grinding material is a high-value waste hard alloy produced in the tungsten product processing field, and the tungsten content thereof can reach 80% to 90%. As a powder-like waste material, the grinding material is suitable for being recycled by using a hydrometallurgical method. The common wet recycling methods for the grinding material mainly include acid recycling and alkali recycling. The acid recycling is to use inorganic acid (such as sulfuric acid, nitric acid and hydrochloric acid) to acid dip the grinding material, so as to dissolve the alloy additives (such as cobalt) in the hard alloy and obtain relatively clean tungsten carbide. The tungsten carbide obtained by the method can be used as a raw material for producing hard alloy for secondary use, and can be further processed into other products. The alkali recycling is to mix dry grinding material with alkali (such as caustic soda, sodium carbonate and sodium nitrate) and then roast and water dip to obtain a crude sodium tungstate solution, and the alloy additives enter the slag phase.

[0003] However, the above methods do not consider the current situation of the hard alloy grinding material raw material. In the rough grinding and fine grinding process of the hard alloy, cutting fluid is often used for auxiliary processing, which results in a certain amount of grease in the grinding material. The grease is difficult to clean by conventional means. Once the grease content is too high, the grease covers the grinding material during acid leaching, hinders the acid decomposition reaction, increases the amount of reagents required for acid leaching, prolongs the acid leaching process, and the separation effect of tungsten and cobalt after acid leaching is not ideal. When the alkali recycling is performed, the volatilization and combustion of the grease during the high-temperature roasting stage will produce a large amount of toxic and harmful smoke and emit a foul odor, which will seriously pollute the atmospheric environment. In addition, the grease will also consume additional roasting additives, increasing the cost of reagents. In addition, the grinding material is generally temporarily stored in a sedimentation tank, and sponge, foam, sandstone and branches and other large pieces of debris will inevitably be mixed therein, which will adversely affect the recycling of the grinding material.

[0004] In response to this situation, Korean patent KR101101755B1 mentions using hexane or ethanol to dissolve cutting oil in grinding media, but it does not address the treatment of large debris pieces. Furthermore, using organic solvents for cleaning poses significant fire hazards and environmental problems. Korean patent KR20080110403A proposes first drying and sieving the sludge generated from cemented carbide machining to remove impurities, then using inorganic acids to separate tungsten carbide. It also proposes using low-temperature calcination to remove cutting oil from the sludge. However, in actual production, dried grinding media are often in relatively hard lumps, making direct sieving difficult. Since the main component of grinding media is tungsten carbide, calcination at too low a temperature will not adequately remove the cutting oil; if the temperature is too high, the grinding media and cutting oil will ignite and eventually oxidize into tungsten oxide, producing harmful gases. At this point, the cobalt in the grinding media undergoes a transformation, making conventional methods for tungsten-cobalt separation impossible. Summary of the Invention

[0005] This application provides a method for separating tungsten and cobalt in cemented carbide abrasives. The separation method of this application can improve the cobalt dissolution rate after acid leaching of the abrasive, reduce the amount of reagent used for tungsten and cobalt separation, accelerate the reaction process of tungsten and cobalt separation, and obtain clean and easily recyclable cemented carbide abrasives.

[0006] The method for separating tungsten and cobalt in cemented carbide abrasives according to this application includes the following steps:

[0007] S1. Obtain grinding material, mix the grinding material with alkali to form a slurry and carry out a saponification reaction, filter to obtain the first filtrate and the first filter residue;

[0008] S2. Dry and crush the first filter residue, perform ultrasonic cleaning, and filter to obtain the second filtrate and the second filter residue.

[0009] S3. Mix the second filter residue and the first acid solution, then add an oxidant to dissolve cobalt, and filter to obtain a cobalt salt solution and a third filter residue, wherein the third filter residue includes tungsten carbide.

[0010] In the above technical solution, the alkali added in step S1 can undergo saponification reaction with oil such as cutting oil, which is conducive to improving the dissolution rate of cobalt after acid leaching of the grinding material, reducing the amount of reagent used for tungsten-cobalt separation, and not increasing the COD treatment burden and fire risk of waste liquid compared with the organic solvent dissolution method; compared with the roasting method, it is more controllable and does not pollute the atmosphere; the ultrasonic cleaning in step S2 can further remove the oil that is not decomposed in step S1, and clean the residual alkali in the pores, which is conducive to further reducing the amount of reagent used for tungsten-cobalt separation; the addition of the first acid solution in step S3 can dissolve cobalt, so that it exists in the form of ions in the first acid solution, and the addition of the oxidizing agent can promote the redox reaction of acid leaching of cobalt, so that the cobalt in the second filter residue can be dissolved in the first acid solution to the greatest extent, while the tungsten exists in the form of tungsten carbide and is not easily dissolved in the first acid solution, thereby the cobalt and tungsten can be well separated by filtration, and the reaction process of tungsten-cobalt separation can be accelerated.

[0011] Further, the alkali in step S2 includes NaOH, KOH or Na2CO3; the concentration of the alkali in the slurry is 0.75-1.5 mol / L; and the mass ratio of water to the grinding material in the slurry is 1.5:1-2.0:1.

[0012] Further, before the saponification reaction in step S1, the grinding material raw material is further subjected to screening treatment to obtain the grinding material; preferably, the grinding material raw material is washed and screened on a screen by using high-pressure water, which can effectively remove impurities, save cost, improve efficiency, and avoid dust pollution; the saponification reaction is carried out at a temperature of 70-100°C for 60-120 min.

[0013] Further, the first acid solution in step S3 includes sulfuric acid or hydrochloric acid, and the second filter residue includes tungsten and cobalt elements; the molar ratio of hydrogen ions in the first acid solution to cobalt elements in the second filter residue is 2.5:1-4.0:1.

[0014] Further, the oxidizing agent in step S3 includes hydrogen peroxide or concentrated nitric acid, and the mass of the oxidizing agent is 10%-15% of the mass of the second filter residue; the oxidizing agent is added to the mixture of the second filter residue and the first acid solution at a constant rate for 4-6 h.

[0015] Further, the leaching rate of cobalt in step S3 is above 95.5%.

[0016] Further, when the pH of the first filtrate is greater than 12, the first filtrate is returned to step S1 for saponification reaction, otherwise it is returned for screening treatment.

[0017] Further, when the pH of the second filtrate is less than 12, the second filtrate is returned to step S2 for ultrasonic cleaning, otherwise it is returned for screening treatment.

[0018] Further, after step S3, the third filter residue is washed and filtered using a second acid solution to obtain a third filtrate; the second acid solution comprises at least one of hydrochloric acid or sulfuric acid, and the pH of the second acid solution is ≤2.

[0019] Further, when the pH of the third filtrate is ≤2, the third filtrate is returned to wash the third filter residue, otherwise, it is returned to step S3 to mix with the second filter residue as an acid solution; the liquid produced in any step of the present application can be used in the next step or returned to other steps, especially, the third filtrate can also be returned to step S3 as an acid solution, which can improve the utilization rate, reduce the recovery cost of cobalt, save water consumption and reduce the burden of wastewater treatment.

[0020] The present application proposes a tungsten-cobalt separation method for hard alloy grinding material, which has the following beneficial effects: improving the dissolution rate of cobalt after acid leaching of the grinding material; reducing the amount of reagent used in tungsten-cobalt separation; accelerating the reaction process of tungsten-cobalt separation; obtaining clean and easy-to-recover hard alloy grinding material; and the wastewater produced in the process can be recycled, and no toxic and harmful gas is produced, which takes into account high efficiency and environmental protection. BRIEF DESCRIPTION OF DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or prior art description will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor on the basis of the drawings shown.

[0022] Figure 1 Process flow chart for tungsten-cobalt recovery method of hard alloy grinding material;

[0023] Figure 2 Process flow chart for the embodiments of the present application.

[0024] The implementation, functional features and advantages of the present application will be further described with reference to the embodiments and the accompanying drawings. DETAILED DESCRIPTION

[0025] The technical solutions in the embodiments will be described below in a clear and complete manner. Obviously, the described embodiments are only some of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0026] Please refer to Figure 1 and Figure 2 , Figure 1A process flow chart for tungsten cobalt recovery method of hard alloy grinding material, Figure 2 A process flow chart for the embodiment of the present application. The technical solution proposed in the present application comprises the following steps:

[0027] S1, obtain grinding material, mix the grinding material and alkali to form a slurry, perform saponification reaction, and filter to obtain first filtrate and first filter residue;

[0028] Specifically, the grinding material raw material is washed and sieved on a 50-100 mesh screen with high-pressure water, the ratio of washing water to grinding material raw material is 1.5:1-2.0:1; the added alkali includes NaOH, KOH or Na2CO3, the concentration of alkali in the prepared slurry is 0.75-1.5 mol / L, and the mass ratio of water to grinding material in the slurry is 1.5:1-2.0:1. Specifically, the concentration of alkali in the prepared slurry is any one of 0.75 mol / L, 0.8 mol / L, 0.9 mol / L, 1.0 mol / L, 1.1 mol / L, 1.2 mol / L, 1.3 mol / L, 1.4 mol / L, 1.5 mol / L or a range between any two of them, and the mass ratio of water to grinding material in the slurry can be any one of 1.5:1, 1.6:1, 1.7:1, 1.8:1, 1.9:1, 2.0:1 or a range between any two of them; the reaction temperature is controlled at 70-100°C, and the reaction time is 60-120 min; when the pH of the first filtrate is greater than 12, the first filtrate is returned to step S1 for saponification reaction, otherwise it is returned for sieving treatment, so as to improve the utilization rate of alkali and reduce water consumption;

[0029] S2, dry and crush the first filter residue, perform ultrasonic cleaning, and filter to obtain second filtrate and second filter residue;

[0030] Specifically, the drying temperature is controlled at 100-120°C, and the first filter residue is crushed to an average particle size of not more than 2 cm; the crushed first filter residue is mixed with pure water for ultrasonic cleaning, the ratio of pure water to first filter residue is 1.0:1-1.5:1, and the ultrasonic cleaning time is 60 min; after ultrasonic cleaning, the supernatant is removed, and then filtering is performed to obtain second filtrate and second filter residue; the second filter residue is clean grinding material, which can be directly used in step S3 or used for baking sodium tungstate after drying; when the pH of the second filtrate is less than 12, the second filtrate is returned to step S2 for ultrasonic cleaning, otherwise it is returned for sieving treatment;

[0031] S3, mix the second filter residue and first acid solution, then add an oxidizing agent and filter to obtain a cobalt salt solution and third filter residue, the third filter residue including tungsten carbide;

[0032] Specifically, the first acid solution comprises hydrochloric acid or sulfuric acid, the second filter residue comprises tungsten elements and cobalt elements, the molar ratio of hydrogen ions in the first acid solution to cobalt elements in the second filter residue is 2.5:1-4.0:1, specifically, the molar ratio of hydrogen ions in the first acid solution to cobalt elements in the second filter residue can be any one of 2.5:1, 3.0:1, 3.5:1, 4.0:1 or a range between any two of them; after the second filter residue is fully infiltrated with the acid and preliminarily reacts, the oxidizing agent is added to the mixture of the second filter residue and the first acid solution at a constant rate, the oxidizing agent comprises hydrogen peroxide or concentrated nitric acid, the mass of the oxidizing agent is 10%-15% of the mass of the second filter residue, the adding time is 4-6h, the slow addition of the oxidizing agent can obtain better results, after the addition of the oxidizing agent is completed, the reaction is continued for 1h to make the oxidizing agent fully participate in the reaction; then the cobalt salt solution and the third filter residue are obtained by filtration, the third filter residue comprises tungsten carbide; then the third filter residue is washed with the second acid solution, the purpose is to wash away the hydrolysis products of Co and Fe elements that may be contained in the third filter residue, the second acid solution comprises at least one of hydrochloric acid or sulfuric acid, the pH of the second acid solution is ≤2, the washing time is 30-60min, and the solid-liquid ratio of the washing liquid is 3:1; the third filtrate and clean tungsten carbide are obtained by filtration, and according to the differences in composition and physical properties, they can be applied to different processing fields; when the pH of the third filtrate is ≤2, the third filtrate is returned to wash the third filter residue, otherwise it is returned to step S3 as an acid solution to mix with the second filter residue, so as to improve the utilization rate of the acid, reduce the recovery cost of cobalt, save the amount of water and reduce the burden of wastewater treatment; the leaching rate of cobalt after the above steps of acid leaching of the grinding material can reach more than 95.5%.

[0033] The technical solutions of the present application are further described below in combination with specific embodiments.

[0034] The raw materials used in each embodiment and comparative example are grinding material raw materials produced in the hard alloy fine grinding process, which are composed of 20wt% of water, 3wt% of grease and 77wt% of grinding material, and the main components of the grinding material are detected as shown in Table 1:

[0035] Table 1 Main components of grinding material

[0036]

[0037] Example 1

[0038] Take 500g of grinding material raw material using 1000mL high pressure water rinse sieve, the obtained grinding material and rinse water stirring uniformity into the decomposition kettle, add 60g of NaOH and open the decomposition kettle stirring into slurry. Set the decomposition kettle heating temperature is 100℃ start heating decomposition, after 120min to slurry solid-liquid separation, get the first filter residue and first filtrate. The first filter residue into the air drying oven at 100℃ drying after broken into small pieces of particle size not more than 2cm. Take 200g broken first filter residue placed in beaker, and add 300mL pure water stirring, the beaker into the ultrasonic cleaning instrument for ultrasonic cleaning 60min, then stand 30min and separate part of the supernatant, the remaining material for solid-liquid separation, get the second filter residue and second filtrate. Using 250mL water and 57.3g concentrated sulfuric acid solution for the second filter residue tungsten cobalt separation, here the hydrogen ion in the acid solution and the cobalt element in the second filter residue molar ratio is 3:1, add 30g hydrogen peroxide as oxidant, here the hydrogen peroxide weight is 15% of the weight of the second filter residue, control the hydrogen peroxide drop time is 5h, continue to react 1h, after filtration get cobalt salt solution and including tungsten carbide third filter residue. And using 200mL mass fraction 1% dilute sulfuric acid on the third filter residue to get the third filtrate and clean tungsten carbide. The Co content of the obtained tungsten carbide is 0.15%, the leaching rate of Co is calculated to be 98.9%; the total water consumption is 1750mL.

[0039] Example 2

[0040] Take 500g of grinding material raw material using 750mL high pressure water rinse sieve, the obtained grinding material and rinse water stirring uniformity into the decomposition kettle, add 45g of NaOH and open the decomposition kettle stirring into slurry. Set the decomposition kettle heating temperature is 100℃ start heating decomposition, after 120min to slurry solid-liquid separation, get the first filter residue and first filtrate. The first filter residue into the air drying oven at 100℃ drying after broken into small pieces of particle size not more than 2cm. Take 200g broken first filter residue placed in beaker, and add 300mL pure water stirring, the beaker into the ultrasonic cleaning instrument for ultrasonic cleaning 60min, then stand 30min and separate part of the supernatant, the remaining material for solid-liquid separation, get the second filter residue and second filtrate. Using 250mL water and 57.3g concentrated sulfuric acid solution for the second filter residue tungsten cobalt separation, here the hydrogen ion in the acid solution and the cobalt element in the second filter residue molar ratio is 3:1, add 30g hydrogen peroxide as oxidant, here the hydrogen peroxide weight is 15% of the weight of the second filter residue, control the hydrogen peroxide drop time is 5h, continue to react 1h, after filtration get cobalt salt solution and including tungsten carbide third filter residue.

[0041] The difference between this embodiment and embodiment 1 is that the amount of water used to rinse the sieved material is reduced from a liquid-solid ratio of 2:1 to 1.5:1, i.e. the mass ratio of water to ground material in the slurry is reduced to 1.5:1, and the rest of the conditions are consistent with embodiment 1. The Co content in the tungsten carbide obtained by testing is 0.19%, and the calculated leaching rate of Co reaches 98.6%.

[0042] Embodiment 3

[0043] Take 500g of ground material raw material and rinse it with 1000mL of high-pressure water, then stir the obtained ground material and rinse water and pour it into a decomposition kettle, add 60g of NaOH and start stirring the decomposition kettle to form a slurry. Set the heating temperature of the decomposition kettle to 70℃ and start heating and decomposing, and after 120min of heat preservation, perform solid-liquid separation on the slurry to obtain first filter residue and first filter liquid. Put the first filter residue into a forced air drying oven and dry it at 100℃, then crush it into small pieces with a particle size of not more than 2cm. Take 200g of the crushed first filter residue and place it in a beaker, add 300mL of pure water and stir it properly, then put the beaker into an ultrasonic cleaning instrument and perform ultrasonic cleaning for 60min, then stand for 30min and separate part of the supernatant, then perform solid-liquid separation on the remaining material to obtain second filter residue and second filter liquid. Use 250mL of water and 57.3g of concentrated sulfuric acid to prepare a solution for tungsten-cobalt separation of the second filter residue, and the molar ratio of hydrogen ions in the acid solution to cobalt elements in the second filter residue is 3:1, add 30g of hydrogen peroxide as an oxidizing agent, and the weight of hydrogen peroxide is 15% of the weight of the second filter residue, control the hydrogen peroxide dropwise adding time for 5h, and continue to react for 1h, then filter to obtain a cobalt salt solution and third filter residue including tungsten carbide.

[0044] The difference between this embodiment and embodiment 1 is that the saponification reaction temperature is reduced from 100℃ to 70℃, and the rest of the conditions are consistent with embodiment 1. The Co content in the tungsten carbide obtained by testing is 0.35%, and the calculated leaching rate of Co reaches 97.4%.

[0045] Embodiment 4

[0046] Take 500g of grinding material raw material, use 1000mL high pressure water to rinse and sieve, stir the obtained grinding material and rinse water, pour into the decomposition kettle, add 60g of NaOH and start the decomposition kettle stirring to form slurry. Set the heating temperature of the decomposition kettle to 100℃, start heating and decomposing, after 60min of heat preservation, solid-liquid separation is carried out on the slurry, to obtain the first filter residue and the first filtrate. Put the first filter residue into the air drying oven at 100℃, dry and crush into small pieces with particle size not exceeding 2cm. Take 200g of the crushed first filter residue, put it in a beaker, add 300mL of pure water, stir appropriately, put the beaker into the ultrasonic cleaning instrument for ultrasonic cleaning for 60min, then stand for 30min and separate part of the supernatant, then perform solid-liquid separation on the remaining material to obtain the second filter residue and the second filtrate. Use 250mL of water and 57.3g of concentrated sulfuric acid to prepare a solution to separate tungsten and cobalt from the second filter residue, the molar ratio of hydrogen ions in the acid solution to cobalt elements in the second filter residue is 3:1, add 30g of hydrogen peroxide as an oxidizing agent, the weight of hydrogen peroxide is 15% of the weight of the second filter residue, control the hydrogen peroxide drop adding time for 5h, continue to react for 1h, after filtration, obtain cobalt salt solution and the third filter residue including tungsten carbide.

[0047] The difference between this embodiment and embodiment 1 is that the alkali dissolution heat preservation time of the grinding material is reduced from 120min to 60min, and the rest of the conditions are consistent with embodiment 1. The Co content in the obtained tungsten carbide is 0.23%, and the calculated Co leaching rate reaches 98.3%.

[0048] Example 5

[0049] Take 500g of grinding material raw material, do not rinse and sieve, only use 1000mL water to stir and pour into the decomposition kettle, add 60g of NaOH and start the decomposition kettle stirring to form slurry. Set the heating temperature of the decomposition kettle to 100℃, start heating and decomposing, after 120min of heat preservation, solid-liquid separation is carried out on the slurry, to obtain the first filter residue and the first filtrate. Put the first filter residue into the air drying oven at 100℃, dry and crush into small pieces with particle size not exceeding 2cm. Take 200g of the crushed first filter residue, put it in a beaker, add 300mL of pure water, stir appropriately, put the beaker into the ultrasonic cleaning instrument for ultrasonic cleaning for 60min, then stand for 30min and separate part of the supernatant, then perform solid-liquid separation on the remaining material to obtain the second filter residue and the second filtrate. Use 250mL of water and 57.3g of concentrated sulfuric acid to prepare a solution to separate tungsten and cobalt from the second filter residue, the molar ratio of hydrogen ions in the acid solution to cobalt elements in the second filter residue is 3:1, add 30g of hydrogen peroxide as an oxidizing agent, the weight of hydrogen peroxide is 15% of the weight of the second filter residue, control the hydrogen peroxide drop adding time for 5h, continue to react for 1h, after filtration, obtain cobalt salt solution and the third filter residue including tungsten carbide.

[0050] The difference between this embodiment and embodiment 1 is that the grinding material is not washed and sieved. The Co content in the obtained tungsten carbide is 0.59%, and the leaching rate of Co is 95.5%. The untreated impurities affect the decomposition reaction, so that the separation effect of tungsten and cobalt is not as good as that of embodiment 1, and the hard impurities in it cause a certain degree of wear to the decomposition equipment.

[0051] Embodiment 6

[0052] Take 500g of grinding material raw material and wash and sieve it with 1000mL high-pressure water, mix the obtained grinding material with the washing water, pour it into the decomposition kettle, add 50g of NaOH, and start the decomposition kettle to stir and mix the slurry. Set the heating temperature of the decomposition kettle to 100℃, start heating and decomposing, and after 120min of heat preservation, perform solid-liquid separation on the slurry to obtain first filter residue and first filtrate. Put the first filter residue into a forced air drying oven at 100℃, dry it, and then crush it into small pieces with a particle size of not more than 2cm. Take 200g of the crushed first filter residue, put it in a beaker, add 300mL of pure water, and stir it properly. Put the beaker into an ultrasonic cleaning instrument to perform ultrasonic cleaning for 60min, then stand for 30min and separate part of the supernatant, and then perform solid-liquid separation on the remaining material to obtain second filter residue and second filtrate. Use 250mL of water and 57.3g of concentrated sulfuric acid to prepare a solution for tungsten-cobalt separation of the second filter residue. The molar ratio of hydrogen ions in the acid solution to cobalt elements in the second filter residue is 3:1, and 30g of hydrogen peroxide is added as an oxidizing agent. The weight of hydrogen peroxide is 15% of the weight of the second filter residue, and the hydrogen peroxide is added for 5h, and then the reaction is continued for 1h. After filtration, a cobalt salt solution and third filter residue including tungsten carbide are obtained.

[0053] The difference between this embodiment and embodiment 1 is that the concentration of sodium hydroxide during the alkali dissolution of the grinding material is reduced from 60g / L to 50g / L. The Co content in the obtained tungsten carbide is 0.48%, and the leaching rate of Co is 96.1%, which is not as good as that of embodiment 1. Reducing the concentration of sodium hydroxide will make the cleaning effect of the pretreatment worse, thereby affecting the separation effect of tungsten and cobalt.

[0054] Embodiment 7

[0055] Take 500g of grinding material raw material using 900mL high pressure water rinse sieve, the obtained grinding material and rinse water stirring uniform pour into the decomposition kettle, add 54g of NaOH and open the decomposition kettle stirring into slurry. Set the decomposition kettle heating temperature is 100℃ start heating decomposition, after 120min to the slurry solid-liquid separation, get the first filter residue and first filtrate. The first filter residue is put into the air drying oven at 100℃ drying after broken into small pieces of particle size not more than 2cm. Take 200g broken first filter residue is placed in beaker, and add 300mL pure water stirring, the beaker is put into ultrasonic cleaning instrument for ultrasonic cleaning 60min, then stand for 30min and separate part of supernatant, again the remaining material solid-liquid separation, get the second filter residue and second filtrate. Using 250mL water and 57.3g concentrated sulfuric acid solution of the second filter residue tungsten cobalt separation, here the hydrogen ion and the second filter residue in the cobalt element molar ratio of 3:1, add 30g hydrogen peroxide as oxidant, here the hydrogen peroxide weight is the weight of the second filter residue 15%, control hydrogen peroxide drop time is 5h, continue to react 1h, after filtration get cobalt salt solution and including tungsten carbide third filter residue.

[0056] The difference between this embodiment and example 1 is that the water amount of rinsing sieve is reduced from liquid-solid ratio 2:1 to 1.8:1, that is, the mass ratio of water to grinding material in the slurry is reduced to 1.8:1, and the rest of the conditions are consistent with example 1. The Co content in the tungsten carbide obtained by detection is 0.22%, and the Co leaching rate is calculated to be 98.4%.

[0057] Example 8

[0058] Take 500g of grinding material raw material using 1000mL high pressure water rinse sieve, the obtained grinding material and rinse water stirring uniform pour into the decomposition kettle, add 60g of NaOH and open the decomposition kettle stirring into slurry. Set the decomposition kettle heating temperature is 80℃ start heating decomposition, after 120min to the slurry solid-liquid separation, get the first filter residue and first filtrate. The first filter residue is put into the air drying oven at 100℃ drying after broken into small pieces of particle size not more than 2cm. Take 200g broken first filter residue is placed in beaker, and add 300mL pure water stirring, the beaker is put into ultrasonic cleaning instrument for ultrasonic cleaning 60min, then stand for 30min and separate part of supernatant, again the remaining material solid-liquid separation, get the second filter residue and second filtrate. Using 250mL water and 57.3g concentrated sulfuric acid solution of the second filter residue tungsten cobalt separation, here the hydrogen ion and the second filter residue in the cobalt element molar ratio of 3:1, add 30g hydrogen peroxide as oxidant, here the hydrogen peroxide weight is the weight of the second filter residue 15%, control hydrogen peroxide drop time is 5h, continue to react 1h, after filtration get cobalt salt solution and including tungsten carbide third filter residue.

[0059] The difference between this embodiment and embodiment 1 is that the saponification reaction temperature is reduced from 100°C to 80°C, and the rest of the conditions are consistent with embodiment 1. The Co content in the obtained tungsten carbide is 0.29%, and the calculated Co leaching rate reaches 97.9%.

[0060] Example 9

[0061] Take 500g of grinding material raw material and wash it through a sieve with 1000mL of high-pressure water. Mix the obtained grinding material with the washing water and pour it into a decomposition kettle. Add 60g of NaOH and start stirring the slurry in the decomposition kettle. Set the heating temperature of the decomposition kettle to 70°C and start heating and decomposing. After 80min of heat preservation, perform solid-liquid separation on the slurry to obtain first filter residue and first filter liquid. Put the first filter residue into a forced air drying oven and dry it at 100°C. Then crush it into small pieces with a particle size of not more than 2cm. Take 200g of the crushed first filter residue and put it into a beaker. Add 300mL of pure water and stir it properly. Put the beaker into an ultrasonic cleaning instrument and perform ultrasonic cleaning for 60min. Then stand for 30min and separate part of the supernatant. Perform solid-liquid separation on the remaining material to obtain second filter residue and second filter liquid. Use 250mL of water and 57.3g of concentrated sulfuric acid to prepare a solution for tungsten-cobalt separation of the second filter residue. The molar ratio of hydrogen ions in the acid solution to cobalt elements in the second filter residue is 3:1. Add 30g of hydrogen peroxide as an oxidizing agent. The weight of hydrogen peroxide is 15% of the weight of the second filter residue. Control the hydrogen peroxide dropwise time for 5h. Continue to react for 1h. After filtration, obtain cobalt salt solution and third filter residue including tungsten carbide.

[0062] The difference between this embodiment and embodiment 1 is that the saponification reaction temperature is reduced from 100°C to 80°C, and the rest of the conditions are consistent with embodiment 1. The Co content in the obtained tungsten carbide is 0.29%, and the calculated Co leaching rate reaches 97.9%.

[0063] Example 10

[0064] Take 500g of grinding material raw material, use 1000mL high-pressure water to rinse and sieve, mix the obtained grinding material with the rinsing water, pour into the decomposition kettle, add 30g of NaOH, and start the decomposition kettle stirring to form slurry. Set the decomposition kettle heating temperature to 100℃, start heating and decomposing, after 120min of heat preservation, the slurry is subjected to solid-liquid separation, obtaining the first filter residue and the first filtrate. The first filter residue is placed in a forced air drying oven at 100℃, dried and crushed into small pieces with a particle size not exceeding 2cm. Take 200g of the crushed first filter residue, place it in a beaker, add 300mL of pure water, stir appropriately, place the beaker in an ultrasonic cleaning instrument for ultrasonic cleaning for 60min, then stand for 30min and separate part of the supernatant, then the remaining material is subjected to solid-liquid separation, obtaining the second filter residue and the second filtrate. Use 250mL of water and 57.3g of concentrated sulfuric acid to prepare a solution for tungsten-cobalt separation of the second filter residue, the molar ratio of hydrogen ions in the acid solution to cobalt elements in the second filter residue is 3:1, add 30g of hydrogen peroxide as an oxidizing agent, the weight of hydrogen peroxide is 15% of the weight of the second filter residue, control the hydrogen peroxide dropwise time for 5h, continue to react for 1h, after filtration, obtain cobalt salt solution and third filter residue including tungsten carbide.

[0065] The difference between this embodiment and example 1 is that the concentration of sodium hydroxide during the alkali dissolution of the grinding material is reduced from 60g / L to 30g / L. The Co content in the obtained tungsten carbide is 0.68%, and the leaching rate of Co is 95.6%, which is not as good as example 1. Reducing the concentration of sodium hydroxide will make the cleaning effect of pretreatment worse, thereby affecting the tungsten-cobalt separation effect.

[0066] Example 11

[0067] First tungsten-cobalt separation:

[0068] Take 500g of grinding material raw material, use 1000mL high pressure water to rinse and sieve, mix the obtained grinding material with the rinsing water, pour into the decomposition kettle, add 60g of NaOH, and start the decomposition kettle stirring to form slurry. Set the decomposition kettle heating temperature to 100℃, start heating and decomposing, after 120min of heat preservation, the slurry is subjected to solid-liquid separation, obtaining the first filter residue and 980mL of the first filtrate, and the first filtrate is recovered. Put the first filter residue into the air drying oven at 100℃, dry and crush into small pieces with particle size not more than 2cm. Take 200g of the crushed first filter residue, put it into a beaker, add 300mL of pure water, stir appropriately, put the beaker into the ultrasonic cleaning instrument for ultrasonic cleaning for 60min, then stand for 30min and separate part of the supernatant, then the remaining material is subjected to solid-liquid separation, obtaining the second filter residue and 300mL of the second filtrate, and the second filtrate is recovered; use 250mL of water and 57.3g of concentrated sulfuric acid to prepare a solution for tungsten-cobalt separation, add 30g of hydrogen peroxide as oxidant, control the hydrogen peroxide dropwise adding time for 5h, continue to react for 1h, after filtration, obtain cobalt salt solution and third filter residue including tungsten carbide. Use 200mL of 1% mass fraction dilute sulfuric acid to wash the third filter residue to obtain 200mL of third filtrate and clean tungsten carbide, and the third filtrate is recovered. The Co content in the obtained tungsten carbide is 0.15%, the leaching rate of Co reaches 98.9% by calculation, the total water consumption of this tungsten-cobalt separation is 1750mL; the pH of the first filtrate in the first tungsten-cobalt separation is >12, the pH of the second filtrate is >12, the pH of the third filtrate is <2, and the second tungsten-cobalt separation is carried out;

[0069] Second tungsten-cobalt separation:

[0070] Take 500 g of the ground material and use 300 mL of the second filtrate from the first tungsten-cobalt separation and 450 mL of water to rinse through a sieve. Mix the obtained ground material with the rinsing water and pour it into a decomposition tank. Add 250 mL of the first filtrate from the first tungsten-cobalt separation and 50 g of NaOH, and start stirring the slurry in the decomposition tank. Set the heating temperature of the decomposition tank to 100°C and start heating and decomposing. After 120 min of heat preservation, perform solid-liquid separation on the slurry to obtain first filter residue and 980 mL of first filtrate, and recycle the first filtrate. Dry the first filter residue in a forced air drying oven at 100°C, and then crush it into small pieces with a particle size of not more than 2 cm. Take 200 g of the crushed first filter residue and place it in a beaker. Add 300 mL of pure water and stir it properly. Place the beaker in an ultrasonic cleaning instrument and perform ultrasonic cleaning for 60 min. Then, stand for 30 min and separate part of the supernatant. Perform solid-liquid separation on the remaining material to obtain second filter residue and 300 mL of second filtrate, and recycle the second filtrate. Use 250 mL of water and 57.3 g of concentrated sulfuric acid to prepare a solution for tungsten-cobalt separation of the second filter residue. Add 30 g of hydrogen peroxide as an oxidizing agent, control the hydrogen peroxide dropwise adding time for 5 h, and continue to react for 1 h. After filtration, obtain cobalt salt solution and third filter residue including tungsten carbide. Use the third filtrate in the first tungsten-cobalt separation to wash the third filter residue to obtain 200 mL of third filtrate and clean tungsten carbide, and recycle the third filtrate. The Co content in the obtained tungsten carbide is 0.20%, and the calculated leaching rate of Co reaches 98.2%. The pH of the first filtrate in the second tungsten-cobalt separation is less than 12, the pH of the second filtrate is greater than 12, and the pH of the third filtrate is greater than 2. The new water consumption in the second tungsten-cobalt separation includes 450 mL of water for rinsing through a sieve, 300 mL of water for ultrasonic cleaning, and 250 mL of water for preparing an acid solution. Other water consumptions are recycled water from the first tungsten-cobalt separation. The new water consumption is reduced from 1750 mL to 1000 mL, the consumption of acid and alkali is reduced, the utilization rate of acid and alkali is improved to a certain extent, and the filtrate recycled in the second tungsten-cobalt separation can be used in the subsequent tungsten-cobalt separation step.

[0071] Example 12

[0072] First tungsten-cobalt separation:

[0073] Take 500g of grinding material raw material, use 1000mL high pressure water to rinse and sieve, mix the obtained grinding material with the rinsing water, pour into the decomposition kettle, add 30g of NaOH, and start the decomposition kettle stirring to form slurry. Set the decomposition kettle heating temperature to 100℃, start heating and decomposing, after 120min of heat preservation, the slurry is subjected to solid-liquid separation, obtaining the first filter residue and 980mL of the first filtrate, the first filtrate is recovered. The first filter residue is placed in a forced air drying oven at 100℃, dried and crushed into small pieces with a particle size of not more than 2cm. Take 200g of the crushed first filter residue, place it in a beaker, add 300mL of pure water, stir appropriately, place the beaker in an ultrasonic cleaning instrument for ultrasonic cleaning for 60min, then stand for 30min and separate part of the supernatant, then the remaining material is subjected to solid-liquid separation, obtaining the second filter residue and 300mL of the second filtrate, the second filtrate is recovered; use 250mL of water and 57.3g of concentrated sulfuric acid to prepare a solution, separate the second filter residue, add 30g of hydrogen peroxide as an oxidizing agent, control the hydrogen peroxide dropwise time for 5h, continue to react for 1h, after filtration, obtain the cobalt salt solution and the third filter residue including tungsten carbide. Use 200mL of 0.5% mass fraction dilute sulfuric acid to wash the third filter residue to obtain 200mL of the third filtrate and clean tungsten carbide, the third filtrate is recovered. The Co content in the obtained tungsten carbide is 0.68%, the Co leaching rate is 95.5%, the total water consumption of this time tungsten-cobalt separation is 1750mL; the pH of the first filtrate in the first tungsten-cobalt separation is <12, the pH of the second filtrate is <12, the pH of the third filtrate is >2, and the second tungsten-cobalt separation is carried out;

[0074] Second tungsten-cobalt separation:

[0075] Take 500g of grinding material raw material, use the first filtrate of the first tungsten-cobalt separation and 20mL of water to rinse the sieve, mix the obtained grinding material with the rinse water, pour it into the decomposition kettle, add 30g of NaOH, and start stirring the slurry. Set the heating temperature of the decomposition kettle to 100℃, start heating and decomposing, and after 120min of heat preservation, perform solid-liquid separation on the slurry to obtain the first filter residue and 980mL of the first filtrate, and recycle the first filtrate. Put the first filter residue into a forced air drying oven and dry it at 100℃, then crush it into small pieces with a particle size of not more than 2cm. Take 200g of the crushed first filter residue, put it in a beaker, add the second filtrate in the first tungsten-cobalt separation, stir appropriately, put the beaker into an ultrasonic cleaning instrument for ultrasonic cleaning for 60min, then stand for 30min and separate part of the supernatant, and then perform solid-liquid separation on the remaining material to obtain the second filter residue and 300mL of the second filtrate, and recycle the second filtrate; use the third filtrate of the first tungsten-cobalt separation, 50mL of water and 57.3g of concentrated sulfuric acid to prepare a solution, separate the second filter residue, add 30g of hydrogen peroxide as an oxidizing agent, control the hydrogen peroxide dropwise adding time for 5h, continue to react for 1h, filter to obtain a cobalt salt solution and a third filter residue containing tungsten carbide. Use 200mL of 0.5% mass fraction dilute sulfuric acid to wash the third filter residue to obtain 200mL of the third filtrate and clean tungsten carbide, and recycle the third filtrate. The Co content in the obtained tungsten carbide is 0.67%, and the calculated Co leaching rate reaches 95.9%; the pH of the first filtrate in the second tungsten-cobalt separation is <12, the pH of the second filtrate is <12, and the pH of the third filtrate is >2; the new water consumption in the second tungsten-cobalt separation includes 20mL of water for rinsing the sieve, 50mL of water for preparing the acid solution, and 200mL of dilute sulfuric acid for washing, and other water is recycled water from the first tungsten-cobalt separation, the new water consumption is reduced from 1750mL to 270mL, and the filtrate recycled in the second tungsten-cobalt separation can also be used in the subsequent tungsten-cobalt separation steps.

[0076] Comparative Example 1

[0077] Take 250g of grinding material raw material, without any pretreatment. Use 250mL of water and 114.6g of concentrated sulfuric acid to prepare a solution for tungsten-cobalt separation, add 60g of hydrogen peroxide as an oxidizing agent, control the hydrogen peroxide dropwise adding time for 7h, and continue to react for 1h.

[0078] The difference between this comparative example and Example 1 is that the grinding material is directly subjected to acid immersion without any treatment, and the amount of acid is doubled, and the amount of oxidizing agent is doubled. The Co content in the obtained tungsten carbide is 8.73% when sampling at 6h of acid immersion, and the leaching is not complete. Therefore, the acid immersion time is prolonged by 2h, about 33%. The Co content in the obtained tungsten carbide is 4.53% after detection, and the leaching rate of Co is only 62.5%. It is shown that the use of the process of the present application for tungsten-cobalt separation of high-fat hard alloy grinding material can reduce the use of acid immersion reagents by 1 times, and only 6h of acid immersion can achieve a much higher cobalt dissolution effect than direct acid immersion for 8h.

[0079] Comparative Example 2

[0080] Take 250g of grinding material raw material, only wash with high-pressure water and sieve, and use 250mL of water and 114.6g of concentrated sulfuric acid to prepare a solution for tungsten-cobalt separation of the obtained grinding material. Add 60g of hydrogen peroxide as an oxidizing agent, control the hydrogen peroxide dropping time for 7h, and continue to react for 1h.

[0081] The difference between this comparative example and Example 1 is that the grinding material is directly subjected to acid immersion after only being washed and sieved, and the amount of acid is doubled, and the amount of oxidizing agent is doubled. The acid immersion time is prolonged by 2h, about 33%. The Co content in the obtained tungsten carbide is 3.98% after detection, and the leaching rate of Co is only 67.1%. The tungsten-cobalt separation effect is slightly better than that of Comparative Example 1.

[0082] Comparative Example 3

[0083] Take 250g of grinding material raw material, wash and sieve with 500mL of high-pressure water, mix the obtained grinding material with the washing water, pour into a decomposition kettle, add 30g of NaOH, and start stirring to form a slurry. Set the heating temperature of the decomposition kettle to 100℃ to start heating and decomposition, and separate the slurry after 120min of heat preservation. Use 250mL of water and 57.3g of concentrated sulfuric acid to prepare a solution for tungsten-cobalt separation of the obtained filter residue, add 30g of hydrogen peroxide as an oxidizing agent, control the hydrogen peroxide dropping time for 5h, continue to react for 1h, and obtain a cobalt salt solution and a filter residue including tungsten carbide after filtration.

[0084] The difference between this comparative example and Example 1 is that the grinding material is not subjected to the steps of drying, crushing and ultrasonic cleaning. The Co content in the obtained tungsten carbide is 0.74% after detection, and the leaching rate of Co is 94.4%. The tungsten-cobalt separation effect is obviously not as good as that of Example 1.

[0085] Comparative Example 4

[0086] Take 250 g of grinding material raw material, use 500 mL high pressure water to rinse sieve, stir the obtained grinding material and rinse water evenly and pour into the decomposition kettle, add 30 g of NaOH and start the decomposition kettle stirring to make slurry. Set the heating temperature of the decomposition kettle to 100℃, start heating and decomposing, after 120 min of heat preservation, the slurry is subjected to solid-liquid separation, obtaining the first filter residue and the first filtrate. The first filter residue is not dried directly, 300 mL of pure water is added, and the material is stirred and ultrasonically cleaned for 60 min, then it is left to stand for 30 min and part of the supernatant is separated, and the remaining material is subjected to solid-liquid separation, obtaining the second filter residue and the second filtrate. Use 250 mL of water and 57.3 g of concentrated sulfuric acid to prepare a solution for tungsten-cobalt separation of the second filter residue, the molar ratio of hydrogen ions in the acid solution to cobalt elements in the second filter residue is 3:1, 30 g of hydrogen peroxide is added as an oxidizing agent, the weight of hydrogen peroxide is 15% of the weight of the second filter residue, the dropping time of hydrogen peroxide is controlled for 5 h, and the reaction is continued for 1 h, then filtration is performed to obtain a cobalt salt solution and a third filter residue containing tungsten carbide.

[0087] The difference between this comparative example and example 1 is that the alkali-dissolved grinding material is not dried and broken directly for ultrasonic cleaning. The Co content in the obtained tungsten carbide is 0.70%, and the leaching rate of Co is 94.7%. The tungsten-cobalt separation effect is close to that of comparative example 3, which is obviously not as good as that of example 1, indicating that the cleaning effect of ultrasonic cleaning and drying and breaking the material is better than that of cleaning the wet material.

[0088] The process flow of each example and comparative example is shown in Table 2:

[0089] Table 2 Summary of process flow of examples and comparative examples

[0090]

[0091]

[0092] By comparing the above examples and comparative examples, it can be seen that the tungsten-cobalt separation method for hard alloy grinding material proposed in the present application can improve the dissolution rate of cobalt after acid leaching of the grinding material, reduce the amount of reagents used for tungsten-cobalt separation, and accelerate the reaction process of tungsten-cobalt separation, obtaining clean and easy-to-recover hard alloy grinding material; and the wastewater generated in the process can be recycled, and no toxic and harmful gas is generated, which takes into account high efficiency and environmental protection.

[0093] The above description is only the preferred embodiments of the present application, and does not limit the patent scope of the present application, and any equivalent structural transformation or direct / indirect application in other related technical fields based on the inventive concept of the present application is included in the patent protection scope of the present application.

Claims

1. A method for separating tungsten and cobalt from cemented carbide grinding stock, characterized in that, The method comprises the following steps: S1, obtaining grinding material, mixing the grinding material with alkali to prepare a slurry for saponification reaction, and filtering to obtain a first filtrate and a first residue; the alkali comprises NaOH, KOH or Na2CO3; S2, drying and crushing the first residue, and performing ultrasonic cleaning, and filtering to obtain a second filtrate and a second residue; S3, mixing the second residue with a first acid solution, the molar ratio of hydrogen ions in the first acid solution to cobalt elements in the second residue being 2.5:1-4.0:1; then adding an oxidizing agent to dissolve cobalt, the oxidizing agent being concentrated nitric acid, the mass of the oxidizing agent being 10%-15% of the mass of the second residue, and filtering to obtain a cobalt salt solution and a third residue, the third residue comprising tungsten carbide; the leaching rate of cobalt reaching 95.5% or more.

2. The method according to claim 1, characterized in that, The concentration of the alkali in the slurry in the step S1 is 0.75-1.5 mol / L; and the mass ratio of water in the slurry to the grinding material is 1.5:1-2.0:

1.

3. The method according to claim 1, wherein the tungsten-cobalt separation method of cemented carbide grinding stock is characterized by, The step S1 further comprises, before the saponification reaction, sieving the grinding material raw material to obtain the grinding material; the reaction temperature of the saponification reaction is 70-100 DEG C, and the reaction time is 60-120 min.

4. The method according to claim 1, wherein the tungsten-cobalt separation method of cemented carbide grinding material is characterized by, The first acid solution in the step S3 comprises at least one of sulfuric acid or hydrochloric acid, and the second residue comprises tungsten elements and cobalt elements.

5. The method according to claim 1, wherein the tungsten-cobalt separation method of cemented carbide grinding material is characterized by, In the step S3, the oxidizing agent is added to the mixture of the second residue and the first acid solution at a constant rate, and the adding time is 4-6 h.

6. The method according to claim 3, wherein the tungsten-cobalt separation method of cemented carbide grinding material is characterized by, When the pH of the first filtrate is greater than 12, the first filtrate is returned to the step S1 for saponification reaction, otherwise it is returned for the sieving treatment.

7. The method according to claim 3, wherein the tungsten-cobalt separation is performed by grinding the cemented carbide grinding material. When the pH of the second filtrate is less than 12, the second filtrate is returned to the step S2 for ultrasonic cleaning, otherwise it is returned for the sieving treatment.

8. The method according to claim 3, wherein the tungsten-cobalt separation method of cemented carbide grinding material is characterized by, After the step S3, a second acid solution is used to wash and filter the third residue to obtain a third filtrate; the second acid solution comprises at least one of hydrochloric acid or sulfuric acid, and the pH of the second acid solution is less than or equal to 2.

9. The method according to claim 8, wherein the tungsten cobalt separation of cemented carbide grinding stock is characterized by, When the pH of the third filtrate is less than or equal to 2, the third filtrate is returned to wash the third residue, otherwise it is returned to the step S3 as an acid solution to mix with the second residue.

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