Method for recovering tungsten from grinding waste slag and application of method

Abstract

The invention provides a method for recycling tungsten from grinding waste slag and application of the method. The method comprises the steps that the grinding waste slag is crushed and screened according to the particle size; the screened grinding waste residues are mixed with a composite leaching agent for leaching; slowly adding a precipitator into the leachate, and filtering to obtain filtrate, namely a tungsten-containing solution subjected to primary impurity removal; chelating resin is adopted for adsorbing the tungsten-containing solution obtained after preliminary impurity removal; after adsorption saturation, desorbing the resin subjected to adsorption saturation by using a tungsten desorption agent; a calcium chloride solution is added into the tungsten-containing desorption solution, and tungsten is separated out in a calcium tungstate precipitation form; and filtering, washing, acidolysis and recrystallization are carried out on the calcium tungstate precipitate, and a high-purity tungsten product is obtained. The method for recycling tungsten from the grinding waste slag is applied to the grinding waste slag generated in the hard alloy machining process, the recycling process is easy to operate, the recycling rate is high, the tungsten product purity is high, environment friendliness is achieved, and the recycling cost is greatly reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of waste resource recovery, and in particular, to a method for recovering tungsten from grinding waste slag and its application. Background Art

[0002] In modern manufacturing, cemented carbide is widely used in fields such as cutting tools and mining machinery due to its excellent properties such as high hardness and wear resistance. However, the grinding waste slag generated during the processing of cemented carbide contains abundant tungsten elements. If not effectively recovered, it will not only cause waste of resources but also may lead to environmental problems.

[0003] Traditional methods for recovering tungsten from grinding waste slag mostly adopt the double-salt roasting process of sodium carbonate and sodium sulfate. Patent CN109911941A discloses a method for extracting sodium tungstate from high-silicon tungsten-containing waste. This method first adds Na2CO3, sulfate, and causticized slag to the high-silicon tungsten-containing waste, mixes them evenly, adds causticized liquid to obtain wet material, then presses the wet material into shape and roasts it to obtain a billet, and separates the billet after ball milling and leaching to obtain a sodium tungstate solution and slag. The method for extracting sodium tungstate from high-silicon tungsten-containing waste specifically includes the following steps: (1) crushing and screening the high-silicon tungsten-containing waste, and the screening mesh size is 100 mesh; (2) adding Na2CO3, sulfate, and causticized slag to the high-silicon tungsten-containing waste, mixing them evenly, and adding causticized liquid to obtain wet material; (3) pressing the wet material obtained in step (2) into shape and roasting it to obtain a billet; (4) ball milling the billet obtained in step (3) with the raffinate, and adding the raffinate again to the mixture obtained by ball milling, and leaching to obtain a slurry; (5) separating the slurry in step (4) to obtain a sodium tungstate solution and slag. Among them, the sulfate is sodium sulfate; the roasting temperature in step (3) is 800 °C, and the roasting time is 6 h.

[0004] The traditional double-salt roasting process of sodium carbonate and sodium sulfate has many drawbacks: the roasting temperature is too high, usually reaching above 800 °C, resulting in huge energy consumption and high costs; and the waste after roasting is prone to form hard lumps, such as cobalt tungstate, and a large amount of tungsten elements are difficult to dissolve fully, greatly increasing the subsequent leaching difficulty. The low leaching efficiency makes it difficult to improve the recovery rate of tungsten. Therefore, it is extremely urgent to develop a new, efficient, and low-cost tungsten recovery method.

[0005] In view of this, the present invention is specifically proposed. Summary of the Invention

[0006] The object of the present invention is to provide a method for recovering tungsten from grinding waste slag in view of the deficiencies of the prior art. It is applied to the grinding waste slag generated during the processing of cemented carbide. The recovery process is simple to operate, has a high recovery rate, high purity of tungsten products, is environmentally friendly, and greatly reduces the recovery cost.

[0007] To achieve the above object of the present invention, the following technical solutions are specifically adopted:

[0008] A method for recovering tungsten from grinding waste slag, comprising the following steps:

[0009] Step S1: Crush the grinding waste slag and screen it according to the particle size;

[0010] Step S2: Mix the screened grinding waste slag with a composite leaching agent for leaching;

[0011] Step S3: Slowly add a precipitating agent to the leaching solution, and the filtrate obtained by filtration is the tungsten-containing solution after preliminary impurity removal;

[0012] Step S4: Adsorb the tungsten-containing solution after preliminary impurity removal with chelating resin;

[0013] Step S5: After adsorption saturation, desorb the saturated resin with a tungsten desorbing agent;

[0014] Step S6: Add a calcium chloride solution to the tungsten-containing desorbing solution, and tungsten precipitates in the form of calcium tungstate;

[0015] Step S7: Filter, wash, acidify and recrystallize the calcium tungstate precipitate to obtain a high-purity tungsten product.

[0016] Further, in step S2, the screened grinding waste slag is mixed with the composite leaching agent at a solid-liquid ratio of 1:6 to 1:9 (g / mL). The composite leaching agent includes a sodium carbonate solution, an alkaline substance and an oxidant. The concentration of the sodium carbonate solution is 150 to 160 g / L. The alkaline substance adjusts the pH value of the leaching system to 10 to 12, and the addition amount of the oxidant is 3% to 5% of the mass of the grinding waste slag.

[0017] Further, in step S2, the temperature during the leaching process is 80 to 100 °C, and continuous stirring leaching is carried out for 3 to 5 h, and the stirring rate is 200 to 300 r / min.

[0018] Further, the alkaline substance is one or a combination of sodium hydroxide, potassium hydroxide, potassium carbonate, sodium phosphate and magnesium oxide.

[0019] Further, the oxidant is one or a combination of sodium peroxide, manganese dioxide, copper oxide, cobalt sesquioxide, sodium hypochlorite.

[0020] Further, in step S3, the precipitating agent is one or a combination of sodium sulfide solution, sodium thiosulfate solution, ferrous sulfide solution, calcium sulfide solution, ammonium sulfide solution; after adding the precipitating agent, the pH of the solution is adjusted to 8 to 9, so that cobalt, nickel, and iron impurities precipitate in the form of sulfides.

[0021] Further, the chelating resin described in step S4 is one of D401 resin, D314 resin, D363 resin, thiourea resin, and LC-500 amino phosphonic acid resin containing amidoxime groups.

[0022] Further, the tungsten desorbent described in step S5 is one or a combination of a sodium hydroxide solution of 2 - 3 mol / L, ammonia water, and a sodium carbonate solution.

[0023] Further, in step S1, grinding waste slag with a particle size of 2 - 6 mm is screened out.

[0024] An application of a method for recovering tungsten from grinding waste slag, which is used for the grinding waste slag generated in the hard alloy processing process.

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0026] 1. The method for recovering tungsten from grinding waste slag of the present invention can greatly reduce the recovery cost. The entire recovery process avoids high - energy - consuming steps such as high - temperature roasting, reducing energy consumption. At the same time, the selected composite leaching agent, adsorption material, and desorbent have relatively low costs, and some reagents can be recycled, resulting in a significant reduction in production costs.

[0027] 2. The method for recovering tungsten from grinding waste slag of the present invention has the advantages of both high yield and high purity. The recovery rate of tungsten resources is as high as 96%, and the purity of the recovered tungsten product is as high as 99.995%, realizing high - efficiency and high - quality recovery of tungsten resources.

[0028] 3. The method for recovering tungsten from grinding waste slag of the present invention is green and environmentally friendly. It abandons the roasting link in the traditional process that may produce a large amount of pollutants, reducing the emission of harmful gases. The composite leaching agent and the reagents used in the subsequent treatment process have extremely low pollution to the environment under reasonable operation. The impurity removal step effectively removes heavy metal impurities through sulfide precipitation, avoiding the harm of heavy metals to the environment and realizing green recovery.

[0029] 4. The method for recovering tungsten from grinding waste slag of the present invention is applied to the grinding waste slag generated in the hard alloy processing process, and has good recovery effects on hard alloy grinding waste slag with different sources and slightly different compositions, having wide applicability. At the same time, each link of the recovery process is easy to operate, easy to realize large - scale production, and can flexibly adjust the processing volume according to actual needs, having strong scalability. Description of the Drawings

[0030] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art. Obviously, the drawings described below are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0031] Figure 1 It is a process flow chart of the method for recovering tungsten from grinding waste slag according to the present invention. Specific embodiments

[0032] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the drawings and specific embodiments. However, those skilled in the art will understand that the following described embodiments are some embodiments of the present invention, rather than all embodiments, and are only used to illustrate the present invention and should not be regarded as limiting the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention. For those conditions not specified in the embodiments, they are carried out according to the conventional conditions or the conditions recommended by the manufacturer. Those reagents or instruments not specified by the manufacturer can be obtained as conventional products through commercial purchase.

[0033] A method for recovering tungsten from grinding waste slag includes the following steps: Step S1: Crush the grinding waste slag and screen it according to the particle size, and screen out the grinding waste slag with a particle size of 2 - 6 mm. The particle size includes but is not limited to 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, 4.5 mm, 5 mm, 5.5 mm, 6 mm;

[0034] Step S2: Mix the screened grinding waste slag with the composite leaching agent at a solid-liquid ratio of 1:6 - 1:9 (g / mL). The solid-liquid ratio includes but is not limited to 1:6 (g / mL), 1:6.5 (g / mL), 1:7 (g / mL), 1:7.5 (g / mL), 1:8 (g / mL), 1:8.5 (g / mL), 1:9 (g / mL). Under the condition that the reaction temperature is 80 - 100 °C, the temperature includes but is not limited to 80 °C, 85 °C, 90 °C, 95 °C, 100 °C, continuously stir and leach for 3 - 5 h, including but not limited to 3 h, 3.5 h, 4 h, 4.5 h, 5 h, and the stirring rate is 200 - 300 r / min, including but not limited to 200 r / min, 210 r / min, 220 r / min, 230 r / min, 240 r / min, 250 r / min, 260 r / min, 270 r / min, 280 r / min, 290 r / min, 300 r / min, to ensure sufficient contact between the grinding waste slag and the composite leaching agent and improve the leaching efficiency; after the leaching is completed, in addition to tungstate ions, cobalt, nickel, and iron impurity ions also exist in the leaching solution;

[0035] Among them, the composite leaching agent includes sodium carbonate (Na2CO3) solution, alkaline substance, and oxidant. The sodium carbonate solution serves as the basic component, providing an alkaline environment and participating in the leaching reaction of tungsten elements at the same time; the concentration of the sodium carbonate solution is 150 - 160 g / L, including but not limited to 150 g / L, 151 g / L, 152 g / L, 153 g / L, 154 g / L, 155 g / L, 156 g / L, 157 g / L, 158 g / L, 159 g / L, 160 g / L. The alkaline substance is one or a combination of sodium hydroxide, potassium hydroxide, potassium carbonate, sodium phosphate, and magnesium oxide. The alkaline substance precisely adjusts the pH value of the leaching system to 10 - 12, and the pH value includes but is not limited to 10, 10.5, 11, 11.5, 12 to promote the dissolution of tungsten; the oxidant is one or a combination of sodium peroxide (Na2O2), manganese dioxide, copper oxide, cobalt sesquioxide, and sodium hypochlorite. The oxidant oxidizes the low-valent tungsten in the grinding waste slag to a high-valent state, enhancing its solubility in the alkaline solution. The addition amount of the oxidant is 3% - 5% of the mass of the grinding waste slag, including but not limited to 3%, 3.5%, 4%, 4.5%, 5%;

[0036] Step S3: Slowly add a precipitant to the leaching solution obtained in Step S2. The precipitant is one or a combination of sodium sulfide solution, sodium thiosulfate solution, ferrous sulfide solution, calcium sulfide solution, and ammonium sulfide solution. Adjust the solution pH to 8 - 9, and the pH value includes but is not limited to 8, 8.1, 8.2, 8.3, 8.4, 8.5, 8.6, 8.7, 8.8, 8.9, 9, so that cobalt, nickel, and iron impurities precipitate in the form of sulfide precipitates; perform solid-liquid separation by filtration, and the obtained filtrate is the tungsten-containing solution after preliminary impurity removal;

[0037] Step S4: Adsorb the tungsten-containing solution after preliminary impurity removal with chelating resin. The chelating resin is one of D401 resin, D314 resin, D363 resin, thiourea resin, and LC-500 amino phosphonic acid resin containing amidoxime groups. The adsorption temperature is 30 - 40 °C, including but not limited to 30 °C, 31 °C, 32 °C, 33 °C, 34 °C, 35 °C, 36 °C, 37 °C, 38 °C, 39 °C, 40 °C. The solution flow rate is 1.2 - 3.0 BV / Hr, including but not limited to 1.2 BV / Hr, 1.4 BV / Hr, 1.6 BV / Hr, 1.8 BV / Hr, 2.0 BV / Hr, 2.2 BV / Hr, 2.4 BV / Hr, 2.6 BV / Hr, 2.8 BV / Hr, 3.0 BV / Hr, so that tungstate ions react with the active groups on the resin to achieve the enrichment of tungsten.

[0038] Step S5: After adsorption saturation, desorb the adsorbed saturated resin with a tungsten desorbent to obtain a high-concentration tungsten-containing desorbing solution. The tungsten desorbent is one or a combination of 2 - 3 mol / L sodium hydroxide solution, ammonia water, and sodium carbonate solution.

[0039] Step S6: Add calcium chloride (CaCl2) solution to the tungsten-containing desorbing solution, and tungsten precipitates in the form of calcium tungstate (CaWO4).

[0040] Step S7: Filter and wash the calcium tungstate precipitate, then dissolve it with dilute hydrochloric acid, and finally obtain a high-purity tungsten product through a recrystallization process.

[0041] Application of a method for recovering tungsten from grinding waste slag. This method is used for the grinding waste slag generated during the processing of cemented carbide. The grinding waste slag includes tungsten carbide (WC), and cobalt (Co), nickel (Ni), and iron (Fe) elements as the binder phase.

[0042] Example 1

[0043] A method for recovering tungsten from grinding waste slag, including the following steps: Step S1: Crush the grinding waste slag, screen it according to the particle size, and screen out the grinding waste slag with a particle size of 2 mm.

[0044] Step S2: Mix the screened grinding waste slag with a composite leaching agent at a solid-liquid ratio of 1:6 (g / mL), and under the condition that the reaction temperature is 80 °C, continuously stir and leach for 3 h, and the stirring rate is 200 r / min.

[0045] Among them, the composite leaching agent includes sodium carbonate solution, sodium hydroxide, and sodium peroxide. The concentration of the sodium carbonate solution is 150 g / L, sodium hydroxide adjusts the pH value of the leaching system to 10, and the addition amount of sodium peroxide is 3% of the mass of the grinding waste slag.

[0046] Step S3: Slowly add a sodium sulfide solution to the leaching solution obtained in Step S2, adjust the pH of the solution to 8, so that cobalt, nickel, and iron impurities precipitate in the form of sulfides, and the filtrate obtained by filtration is the tungsten-containing solution after preliminary impurity removal;

[0047] Step S4: Adsorb the tungsten-containing solution after preliminary impurity removal with chelating resin. The chelating resin is D401 resin containing amidoxime groups, the adsorption temperature is 30 °C, and the solution flow rate is 1.2 BV / Hr;

[0048] Step S5: After adsorption saturation, desorb the saturated resin with a 2 mol / L sodium hydroxide solution to obtain a high-concentration tungsten-containing desorbing solution;

[0049] Step S6: Add a calcium chloride solution to the tungsten-containing desorbing solution, and tungsten precipitates in the form of calcium tungstate;

[0050] Step S7: Filter and wash the calcium tungstate precipitate, then dissolve it with dilute hydrochloric acid, and finally obtain a high-purity tungsten product through a recrystallization process.

[0051] Example 2

[0052] A method for recovering tungsten from grinding waste slag, comprising the following steps: Step S1: Crush the grinding waste slag, screen it according to the particle size, and screen out the grinding waste slag with a particle size of 3 mm;

[0053] Step S2: Mix the screened grinding waste slag with a composite leaching agent at a solid-liquid ratio of 1:7 (g / mL), and under the condition that the reaction temperature is 85 °C, continuously stir and leach for 3.5 h, and the stirring rate is 240 r / min;

[0054] Among them, the composite leaching agent includes a sodium carbonate solution, potassium hydroxide, and manganese dioxide. The concentration of the sodium carbonate solution is 152 g / L, potassium hydroxide adjusts the pH value of the leaching system to 10, and the addition amount of manganese dioxide is 3.5% of the mass of the grinding waste slag;

[0055] Step S3: Slowly add a sodium thiosulfate solution to the leaching solution obtained in Step S2, adjust the pH of the solution to 8.2, so that cobalt, nickel, and iron impurities precipitate in the form of sulfides, and the filtrate obtained by filtration is the tungsten-containing solution after preliminary impurity removal;

[0056] Step S4: Adsorb the tungsten-containing solution after preliminary impurity removal with chelating resin. The chelating resin is D314 resin, the adsorption temperature is 32 °C, and the solution flow rate is 1.8 BV / Hr;

[0057] Step S5: After adsorption saturation, desorb the saturated resin with a 3 mol / L sodium hydroxide solution to obtain a high-concentration tungsten-containing desorbing solution;

[0058] Step S6: Add a calcium chloride solution to the tungsten-containing desorption solution, and tungsten precipitates in the form of calcium tungstate.

[0059] Step S7: Filter and wash the calcium tungstate precipitate, then dissolve it with dilute hydrochloric acid, and finally obtain high-purity tungsten products through a recrystallization process.

[0060] Example 3

[0061] A method for recovering tungsten from grinding waste slag, comprising the following steps: Step S1: Crush the grinding waste slag, screen it according to the particle size, and screen out the grinding waste slag with a particle size of 4 mm;

[0062] Step S2: Mix the screened grinding waste slag with a composite leaching agent at a solid-liquid ratio of 1:8 (g / mL), and continuously stir and leach for 4 h at a reaction temperature of 85 °C with a stirring rate of 260 r / min;

[0063] Among them, the composite leaching agent includes a sodium carbonate solution, potassium carbonate, and copper oxide. The concentration of the sodium carbonate solution is 155 g / L, the pH value of the leaching system is adjusted to 11 with potassium carbonate, and the addition amount of copper oxide is 4% of the mass of the grinding waste slag;

[0064] Step S3: Slowly add a ferrous sulfide solution to the leaching solution obtained in Step S2, adjust the solution pH to 8.5, so that cobalt, nickel, and iron impurities precipitate in the form of sulfides, and the filtered filtrate is a tungsten-containing solution after preliminary impurity removal;

[0065] Step S4: Adsorb the tungsten-containing solution after preliminary impurity removal with chelating resin. The chelating resin is D363 resin, the adsorption temperature is 34 °C, and the solution flow rate is 2.4 BV / Hr;

[0066] Step S5: After adsorption saturation, desorb the saturated resin with ammonia water to obtain a high-concentration tungsten-containing desorption solution;

[0067] Step S6: Add a calcium chloride solution to the tungsten-containing desorption solution, and tungsten precipitates in the form of calcium tungstate.

[0068] Step S7: Filter and wash the calcium tungstate precipitate, then dissolve it with dilute hydrochloric acid, and finally obtain high-purity tungsten products through a recrystallization process.

[0069] Example 4

[0070] A method for recovering tungsten from grinding waste slag, comprising the following steps: Step S1: Crush the grinding waste slag, screen it according to the particle size, and screen out the grinding waste slag with a particle size of 5 mm;

[0071] Step S2: Mix the sieved grinding waste slag with the composite leaching agent at a solid-liquid ratio of 1:8 (g / mL). Under the condition that the reaction temperature is 90 °C, continuously stir and leach for 4.5 h, and the stirring rate is 280 r / min;

[0072] Among them, the composite leaching agent includes sodium carbonate solution, sodium phosphate and cobalt sesquioxide. The concentration of the sodium carbonate solution is 157 g / L, the sodium phosphate adjusts the pH value of the leaching system to 11, and the addition amount of cobalt sesquioxide is 4.5% of the mass of the grinding waste slag;

[0073] Step S3: Slowly add calcium sulfide solution to the leaching solution obtained in Step S2, adjust the solution pH to 8.5, so that cobalt, nickel and iron impurities precipitate in the form of sulfide, and the filtered filtrate is the tungsten-containing solution after preliminary impurity removal;

[0074] Step S4: Use chelating resin to adsorb the tungsten-containing solution after preliminary impurity removal. The chelating resin is thiourea resin, the adsorption temperature is 36 °C, and the solution flow rate is 2.4 BV / Hr;

[0075] Step S5: After adsorption saturation, desorb the saturated resin with ammonia water to obtain a high-concentration tungsten-containing desorbing solution;

[0076] Step S6: Add calcium chloride solution to the tungsten-containing desorbing solution, and tungsten precipitates in the form of calcium tungstate;

[0077] Step S7: Filter and wash the calcium tungstate precipitate, then dissolve it with dilute hydrochloric acid, and finally obtain high-purity tungsten products through a recrystallization process.

[0078] Example 5

[0079] A method for recovering tungsten from grinding waste slag, comprising the following steps: Step S1: Crush the grinding waste slag, screen according to the particle size, and screen out the grinding waste slag with a particle size of 6 mm;

[0080] Step S2: Mix the sieved grinding waste slag with the composite leaching agent at a solid-liquid ratio of 1:9 (g / mL). Under the condition that the reaction temperature is 100 °C, continuously stir and leach for 5 h, and the stirring rate is 300 r / min;

[0081] Among them, the composite leaching agent includes sodium carbonate solution, magnesium oxide and sodium hypochlorite. The concentration of the sodium carbonate solution is 160 g / L, the magnesium oxide adjusts the pH value of the leaching system to 12, and the addition amount of sodium hypochlorite is 5% of the mass of the grinding waste slag;

[0082] Step S3: Slowly add ammonium sulfide solution to the leaching solution obtained in Step S2, adjust the solution pH to 9, so that cobalt, nickel and iron impurities precipitate in the form of sulfide, and the filtered filtrate is the tungsten-containing solution after preliminary impurity removal;

[0083] Step S4: Adsorb the tungsten-containing solution after preliminary impurity removal with chelating resin. The chelating resin is LC-500 amino phosphonic acid resin, the adsorption temperature is 40°C, and the solution flow rate is 3 BV / Hr;

[0084] Step S5: After adsorption saturation, desorb the saturated resin with sodium carbonate solution to obtain a high-concentration tungsten-containing desorbing solution;

[0085] Step S6: Add calcium chloride solution to the tungsten-containing desorbing solution, and tungsten precipitates in the form of calcium tungstate;

[0086] Step S7: Filter and wash the calcium tungstate precipitate, then dissolve it with dilute hydrochloric acid, and finally obtain high-purity tungsten products through a recrystallization process.

[0087] Test example:

[0088] I. The tungsten recovery rate and the purity of tungsten products in Example 1 are shown in Table 1.

[0089] Table 1 Tungsten recovery rate and purity of tungsten products in Example 1

[0090]

[0091] II. The detection data of the contents of other metals in the high-purity tungsten products prepared in Example 1 are shown in Table 2

[0092] Table 2 Detection data of the contents of other metals in tungsten products in Example 1

[0093]

[0094]

Claims

1. A method for recovering tungsten from grinding waste slag, characterized in that, It includes the following steps: Step S1: Crush the grinding waste slag and screen it according to the particle size; Step S2: Mix the screened grinding waste slag with a composite leaching agent for leaching; Step S3: Slowly add a precipitating agent to the leaching solution, and the filtrate obtained by filtration is the tungsten-containing solution after preliminary impurity removal; Step S4: Use chelating resin to adsorb the tungsten-containing solution after preliminary impurity removal; Step S5: After adsorption saturation, use a tungsten desorbing agent to desorb the resin saturated with adsorption; Step S6: Add a calcium chloride solution to the tungsten-containing desorbing solution, and tungsten precipitates in the form of calcium tungstate; Step S7: Filter, wash, acidify, and recrystallize the calcium tungstate precipitate to obtain a high-purity tungsten product.

2. The method for recovering tungsten from grinding waste slag according to claim 1, wherein In Step S2, the screened grinding waste slag is mixed with the composite leaching agent at a solid-liquid ratio of 1:6 - 1:9 g / mL. The composite leaching agent includes a sodium carbonate solution, an alkaline substance, and an oxidant. The concentration of the sodium carbonate solution is 150 - 160 g / L. The alkaline substance adjusts the pH value of the leaching system to 10 - 12, and the addition amount of the oxidant is 3% - 5% of the mass of the grinding waste slag.

3. The method for recovering tungsten from grinding waste slag according to claim 1 or 2, characterized in that, In Step S2, the temperature during the leaching process is 80 - 100 °C, and continuous stirring leaching is carried out for 3 - 5 h, and the stirring rate is 200 - 300 r / min.

4. The method for recovering tungsten from grinding waste slag according to claim 2, wherein The alkaline substance is one or a combination of sodium hydroxide, potassium hydroxide, potassium carbonate, sodium phosphate, and magnesium oxide.

5. The method for recovering tungsten from grinding waste slag according to claim 2, characterized in that, The oxidant is one or a combination of sodium peroxide, manganese dioxide, copper oxide, cobalt sesquioxide, and sodium hypochlorite.

6. The method for recovering tungsten from grinding waste slag according to claim 1, characterized in that, In Step S3, the precipitating agent is one or a combination of sodium sulfide solution, sodium thiosulfate solution, ferrous sulfide solution, calcium sulfide solution, and ammonium sulfide solution; after adding the precipitating agent, the pH of the solution is adjusted to 8 - 9 to precipitate cobalt, nickel, and iron impurities in the form of sulfide precipitates.

7. The method for recovering tungsten from grinding waste slag according to claim 1, characterized in that, In Step S4, the chelating resin is one of D401 resin, D314 resin, D363 resin, thiourea resin, and LC-500 amino phosphonic acid resin containing amidoxime groups.

8. The method for recovering tungsten from grinding waste slag according to claim 1, characterized in that, In Step S5, the tungsten desorbing agent is one or a combination of 2 - 3 mol / L sodium hydroxide solution, ammonia water, and sodium carbonate solution.

9. The method for recovering tungsten from grinding waste slag according to claim 1, wherein, In Step S1, the screened grinding waste slag has a particle size of 2 - 6 mm.

10. An application of a method for recovering tungsten from grinding waste slag, using this method for the grinding waste slag generated in the hard alloy processing process.

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