Method for recovering tungsten in causticized slag

Abstract

The invention relates to the technical field of recovery of valuable metals in causticized slag, in particular to a method for recovering tungsten in causticized slag, which utilizes the characteristics that tungsten contained in the causticized slag mainly exists in the form of sodium tungstate and Na2WO4 can be dissolved in water, comprises the following steps: firstly, leaching tungsten in the causticized slag by adopting a water leaching method without additionally adding acid and alkali, and then leaching tungsten in the causticized slag by adopting a water leaching method, according to the method, tungsten ions in water leaching liquid are recycled through an ion exchange method, separation of the tungsten ions and other soluble impurity elements is achieved through the characteristic that alkalescent anion resin adsorbs metatungstate in an acid environment, the method combining the water leaching process and the ion exchange process is adopted, valuable metal can be highly leached and recycled, and the method is suitable for industrial production. The metal recovery rate is high, loss of valuable metal in the slag is reduced, waste of tungsten resources is avoided, the process is simple, operability is high, the production cost is low, environment friendliness is achieved, and the tungsten recovery cost is greatly reduced.

Description

Technical Field

[0001] The invention relates to the technical field of recovering valuable metals in causticized slag, and in particular to a method for recovering tungsten in causticized slag. Background Art

[0002] In the process of tungsten smelting enterprises using the "soda pressure cooking-alkaline extraction" technology to treat scheelite and its leachate, in order to achieve a closed-loop circulation of the water phase between the "leaching-extraction" process, the raffinate is returned to the leaching process. However, the NaHCO contained in the raffinate 3 It will affect the pH value of the system and is not conducive to the leaching of tungsten. Therefore, before the raffinate is returned to the leaching process, lime and liquid alkali are added to it to 3 The caustic soda ash is converted into tungsten and then separated into solid and liquid by a plate and frame filter press. The converted solution is returned to the leaching process, and the slag produced during the conversion process is called causticized slag. The accumulation of a large amount of causticized slag not only occupies land and pollutes the surrounding environment, but also has a high tungsten content in the causticized slag due to the limitations of the solid-liquid separation process. It is necessary to recycle it.

[0003] Most of the metal recovery in causticized slag uses wet extraction, such as using sodium hydroxide or high-concentration acid to leach metals from the slag. Although acid leaching can effectively extract the target metal, the metal oxides in the slag will inevitably be decomposed, which will increase the difficulty of subsequent purification and impurity removal processes. Although alkaline leaching can better ensure the purity of the leachate, the efficiency of alkaline leaching is low, and it is often necessary to increase the amount of reagents input to efficiently leach metal ions, which also means higher production costs. Therefore, tungsten smelting companies are in urgent need of seeking a low-cost, high-recovery process to achieve a better "enrichment" of tungsten elements in high-tungsten causticized slag, thereby achieving a win-win situation for environmental protection and corporate economic benefits.

[0004] At present, there are three main methods for extracting tungsten from solution in industry: ion exchange, solvent extraction, and chemical precipitation. Solvent extraction extracts the target element based on the difference in solubility of different elements in the solution. Chemical precipitation achieves the purpose of element separation by generating insoluble salt precipitates through chemical reactions. The above two methods have relatively serious environmental pollution, large reagent consumption, low metal extraction rate, high impurity content and other problems. Ion exchange is to achieve selective adsorption of ions by selecting specific resins to react with certain ions in the solution. Relatively speaking, ion exchange has the advantages of simple operation, low equipment corrosion, and high metal recovery rate. Summary of the invention

[0005] In order to solve the problem in the background technology, the present invention discloses a method for recovering tungsten in causticized slag. The causticized slag is pretreated with deionized water, and then the metallic tungsten in the water leaching liquid is recovered by an ion exchange method. The method has low cost, short process flow, does not cause new environmental pollution during production, and is easy to implement in large-scale production lines.

[0006] In order to achieve the above-mentioned invention object, the present invention adopts the following technical scheme: A method for recovering tungsten from causticized slag, characterized in that it comprises the following steps: (1) pre-treating the causticized slag: uniformly mixing deionized water and the causticized slag to obtain a mixed slurry of the causticized slag and deionized water, and filtering the mixed slurry to obtain a water extract and water-extracted slag; (2) Separating tungsten ions from other soluble salts in the water extract: adjusting the pH value of the water extract obtained in step (1) to 2-3, so that tungstate in the water extract is acidified to metatungstate ions, using a weakly alkaline anion exchange resin to selectively adsorb metatungstate in the acidic water extract, so that tungsten ions in the acidic water extract are separated from other soluble salts, and an anion exchange resin and a post-exchange liquid adsorbing tungsten are obtained. The weakly alkaline anion resin used in the present invention has obvious selective adsorption of tungsten ions. For the acid-treated tungsten-containing water extract, the amount of anion resin used must ensure that the tungsten ions contained in the extract are completely adsorbed; (3) Extracting tungsten ions from the water extract: The saturated negative tungsten anion exchange resin obtained in step (2) is decomposed with a sodium hydroxide solution to obtain a pure sodium tungstate solution. The decomposed resin is regenerated with an acid solution and can be used for the next adsorption cycle. The acid solution used for regeneration is sulfuric acid or nitric acid. Considering the reagent cost, sulfuric acid is preferred. The reaction equation occurring during the decomposition process is as follows: H 2 W 12 O 40 6- + OH - = WO 3 2- + H 2 O Furthermore, in the method for recovering tungsten from causticized slag, in step (1), the liquid-to-solid ratio of deionized water to causticized slag is 2-4 mL / g, the leaching temperature is 50-80°C, and the leaching time is 10-30 min. The setting of the leaching liquid-to-solid ratio, leaching temperature and leaching time is to allow the causticized slag to fully react with the aqueous solution and better leach the tungsten from the causticized slag.

[0007] Furthermore, in the method for recovering tungsten from causticized slag, the concentration of tungsten ions in the water leaching solution in step (1) is 1-5 g / L.

[0008] Furthermore, in the method for recovering tungsten from causticized slag, the main component of the causticized slag is calcium carbonate, CaCO 3 The mass percentage of WO is 90-98%, and the causticized slag contains WO 3 The mass percentage of sodium tungstate in form is 0.5~1%.

[0009] Furthermore, in the method for recovering tungsten from causticized slag, in step (2), the pH value of the water extract is adjusted using concentrated sulfuric acid with a mass fraction of 98%.

[0010] Furthermore, in the method for recovering tungsten from causticized slag, the anion exchange resin used in step (2) is a D314 macroporous weakly basic anion exchange resin.

[0011] Furthermore, in the method for recovering tungsten from causticized slag, if the concentration of tungsten ions in the liquid obtained after handover in step (2) is less than 0.2 g / L, it means that the resin is not saturated with adsorption, and the liquid after handover is returned to step (1) for leaching the next batch of causticized slag to reduce water consumption. It should be noted that if the concentration of tungsten ions in the liquid after handover obtained in step (2) is ≥ 0.2 g / L, it means that the resin is saturated with adsorption and the amount of adsorption resin needs to be increased.

[0012] Furthermore, in the method for recovering tungsten from causticized slag, the sodium tungstate solution obtained after analysis in step (3) is returned to the main process flow of scheelite treatment.

[0013] Furthermore, in the method for recovering tungsten from causticized slag, the concentration of the sodium hydroxide solution used for decomposition in step (3) is 1-5 mol / L, and the amount of the sodium hydroxide solution used should ensure that all the tungsten in the negative tungsten resin is decomposed, that is, the amount of the sodium hydroxide solution used must exceed the theoretical amount of the negative tungsten resin for complete decomposition. During desorption, the flow rate of the sodium hydroxide solution through the resin adsorption column is preferably 1-3 BV.

[0014] Furthermore, in the method for recovering tungsten from causticized slag, the leached slag obtained in step (1) can be sold as building materials.

[0015] Compared with the prior art, the present invention has the following beneficial effects: The method for recovering tungsten from causticized slag disclosed in the present invention utilizes that the tungsten contained in the causticized slag mainly exists in the form of sodium tungstate, Na 2 WO 4The invention has the characteristic of being soluble in water. Firstly, the tungsten in the causticized slag is leached by water leaching method. The tungsten in the causticized slag can be leached without adding additional acid or alkali. Then, the tungsten ions in the water leaching liquid are recovered by ion exchange method. The weak alkaline anion resin can adsorb metatungstate in an acidic environment to separate tungsten ions from other soluble impurity elements. The exchange liquid produced by ion exchange can still be used to leach tungsten in the causticized slag for recycling. The water consumption is small and the environment is friendly. While saving water, the production cost is also reduced. The invention adopts a method combining water leaching process with ion exchange process, which can highly leach and recover valuable metals, has a high metal recovery rate, reduces the loss of valuable metals in the slag, avoids the waste of tungsten resources, and has simple process, strong operability, low production cost, and is environmentally friendly, which greatly reduces the tungsten recovery cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a process flow chart of the present invention. DETAILED DESCRIPTION

[0017] In order to better understand the present invention, the content of the present invention is further clearly set forth in conjunction with the embodiments below, but the protection content of the present invention is not limited to the following embodiments. In the following description, a large number of specific details are provided in order to provide a more thorough understanding of the present invention. However, it is obvious to those skilled in the art that the present invention can be implemented without one or more of these details. Example 1

[0018] 500 g of sandy causticized slag was weighed, and the causticized slag was mixed with deionized water for water immersion to prepare a mixed slurry. The liquid-to-solid ratio of the causticized slag to deionized water was 2 mL / g, the water immersion temperature was 50-80°C, and the water immersion time was controlled to be 10-30 min. Then the slurry was filtered to produce a tungsten-containing water leaching solution and water leaching slag. The tungsten content was measured after the water leaching slag was dried. The tungsten leaching rate calculated by the slag was 92.3%, and the tungsten ion concentration in the water leaching solution was 4.22 g / L. The pH of the tungsten-containing water leaching solution was adjusted to 2.5 with sulfuric acid solution, and D314 anion exchange resin was used for adsorption. The amount of anion resin ensured that the tungsten ions contained in the leaching solution were completely adsorbed. After the adsorption was completed, negative tungsten anion exchange resin and post-delivery liquid were obtained. The tungsten ion concentration in the post-delivery liquid was less than 0.2 g / L. The post-delivery liquid was returned to the leaching process for leaching the next batch of causticized slag, which consumed less water and was environmentally friendly. After the negative tungsten anion exchange resin is decomposed by mol / L sodium hydroxide solution, a pure tungstate solution is obtained, which is returned to the main process flow of scheelite treatment. The flow rate of the sodium hydroxide solution through the resin adsorption column is preferably 1~3 BV, completing the separation and extraction and recovery of tungsten in the tungsten-containing water leachate. Finally, sulfuric acid is used to regenerate the decomposed resin for recycling. Example 2

[0019] 500 g of sandy causticized slag was weighed, and the causticized slag was mixed with deionized water for water immersion to prepare a mixed slurry. The liquid-to-solid ratio of the causticized slag to deionized water was 2.5 mL / g, the water immersion temperature was 50-80°C, and the water immersion time was controlled to be 10-30 min. Then the slurry was filtered to produce a tungsten-containing water leaching solution and water leaching slag. The tungsten content was measured after the water leaching slag was dried. The tungsten leaching rate calculated by the slag was 93.1%, and the tungsten ion concentration in the water leaching solution was 3.25 g / L. The pH of the tungsten-containing water leaching solution was adjusted to 2.5 with sulfuric acid solution, and D314 anion exchange resin was used for adsorption. The amount of anion resin ensured that the tungsten ions contained in the leaching solution were completely adsorbed. After the adsorption was completed, negative tungsten anion exchange resin and post-exchange liquid were obtained. The tungsten ion concentration in the post-exchange liquid was less than 0.2 g / L. The post-exchange liquid was returned to the leaching process for leaching the next batch of causticized slag, which consumed less water and was environmentally friendly. After the saturated negative tungsten anion exchange resin is decomposed by mol / L sodium hydroxide solution, a pure tungstate solution is obtained, which is returned to the main process flow of scheelite treatment. The flow rate of the sodium hydroxide solution through the resin adsorption column is preferably 1-3 BV, so as to complete the separation and extraction and recovery of tungsten in the tungsten-containing water leachate. Finally, sulfuric acid is used to regenerate the decomposed resin for recycling. Example 3

[0020] 500 g of sandy causticized slag was weighed, and the causticized slag was mixed with deionized water for water immersion to prepare a mixed slurry. The liquid-to-solid ratio of the causticized slag to the deionized water was 3 mL / g, the water immersion temperature was 50-80°C, and the water immersion time was controlled to be 10-30 min. Then the slurry was filtered to produce a tungsten-containing water leaching solution and water leaching slag. The tungsten content was measured after the water leaching slag was dried. The tungsten leaching rate calculated by the slag was 95.1%, and the tungsten ion concentration in the water leaching solution was 2.78 g / L. The pH of the tungsten-containing water leaching solution was adjusted to 2.5 with sulfuric acid solution, and D314 anion exchange resin was used for adsorption. The amount of anion resin ensured that the tungsten ions contained in the leaching solution were completely adsorbed. After the adsorption was completed, negative tungsten anion exchange resin and post-delivery liquid were obtained. The tungsten ion concentration in the post-delivery liquid was less than 0.2 g / L. The post-delivery liquid was returned to the leaching process for leaching the next batch of causticized slag, which consumed less water and was environmentally friendly. After the saturated negative tungsten anion exchange resin is decomposed by mol / L sodium hydroxide solution, a pure tungstate solution is obtained, which is returned to the main process flow of scheelite treatment. The flow rate of the sodium hydroxide solution through the resin adsorption column is preferably 1-3 BV, so as to complete the separation and extraction and recovery of tungsten in the tungsten-containing water leachate. Finally, sulfuric acid is used to regenerate the decomposed resin for recycling. Example 4

[0021] 500 g of sandy causticized slag was weighed, and the causticized slag was mixed with deionized water for water immersion to prepare a mixed slurry. The liquid-to-solid ratio of the causticized slag to deionized water was 3.5 mL / g, the water immersion temperature was 50-80°C, and the water immersion time was controlled to be 10-30 min. Then the slurry was filtered to produce a tungsten-containing water leaching solution and water leaching slag. The tungsten content was measured after the water leaching slag was dried. The tungsten leaching rate calculated by the slag was 95.9%, and the tungsten ion concentration in the water leaching solution was 2.32 g / L. The pH of the tungsten-containing water leaching solution was adjusted to 2.5 with sulfuric acid solution, and D314 anion exchange resin was used for adsorption. The amount of anion resin ensured that the tungsten ions contained in the leaching solution were completely adsorbed. After the adsorption was completed, negative tungsten anion exchange resin and post-delivery liquid were obtained. The tungsten ion concentration in the post-delivery liquid was less than 0.2 g / L. The post-delivery liquid was returned to the leaching process for leaching the next batch of causticized slag, which consumed less water and was environmentally friendly. After the saturated negative tungsten anion exchange resin is decomposed by mol / L sodium hydroxide solution, a pure tungstate solution is obtained, which is returned to the main process flow of scheelite treatment. The flow rate of the sodium hydroxide solution through the resin adsorption column is preferably 1-3 BV, so as to complete the separation and extraction and recovery of tungsten in the tungsten-containing water leachate. Finally, sulfuric acid is used to regenerate the decomposed resin for recycling. Example 5

[0022] 500 g of sandy causticized slag was weighed, and the causticized slag was mixed with deionized water for water immersion to prepare a mixed slurry. The liquid-to-solid ratio of the causticized slag to deionized water was 4 mL / g, the water immersion temperature was 50-80°C, and the water immersion time was controlled to be 10-30 min. Then the slurry was filtered to produce a tungsten-containing water leaching solution and water leaching slag. The tungsten content was measured after the water leaching slag was dried. The tungsten leaching rate calculated by the slag was 96.4%, and the tungsten ion concentration in the water leaching solution was 1.98 g / L. The pH of the tungsten-containing water leaching solution was adjusted to 2.5 with sulfuric acid solution, and D314 anion exchange resin was used for adsorption. The amount of anion resin ensured that the tungsten ions contained in the leaching solution were completely adsorbed. After the adsorption was completed, negative tungsten anion exchange resin and post-exchange liquid were obtained. The tungsten ion concentration in the post-exchange liquid was less than 0.2 g / L. The post-exchange liquid was returned to the leaching process for leaching the next batch of causticized slag, which consumed less water and was environmentally friendly. After the saturated negative tungsten anion exchange resin is decomposed by mol / L sodium hydroxide solution, a pure tungstate solution is obtained, which is returned to the main process flow of scheelite treatment. The flow rate of the sodium hydroxide solution through the resin adsorption column is preferably 1-3 BV, so as to complete the separation and extraction and recovery of tungsten in the tungsten-containing water leachate. Finally, sulfuric acid is used to regenerate the decomposed resin for recycling.

[0023] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Other modifications or equivalent substitutions made to the technical solution of the present invention by ordinary technicians in the field should be included in the scope of the claims of the present invention as long as they do not depart from the spirit and scope of the technical solution of the present invention.

Claims

1. A method for recovering tungsten from causticized slag, characterized in that: The steps include: (1) pre-treating the causticized slag: uniformly mixing deionized water and the causticized slag to obtain a mixed slurry of the causticized slag and deionized water, and filtering the mixed slurry to obtain a water extract and water-extracted slag; (2) Separating tungsten ions from other soluble salts in the water extract: adjusting the pH value of the water extract obtained in step (1) to 2-3, so that tungstate in the water extract is acidified to metatungstate ions, and using a weakly alkaline anion exchange resin to selectively adsorb metatungstate in the acidic water extract to separate tungsten ions from other soluble salts in the acidic water extract, thereby obtaining an anion exchange resin adsorbing tungsten and a post-exchange liquid; (3) Extracting tungsten ions from the water extract: The anion exchange resin adsorbing tungsten obtained in step (2) is decomposed with a sodium hydroxide solution to obtain a sodium tungstate solution.

2. The method for recovering tungsten from causticized slag according to claim 1, characterized in that: In step (1), the liquid-to-solid ratio of deionized water to causticized slag is 2-4 mL / g, the leaching temperature is 50-80 °C, and the leaching time is 10-30 min.

3. The method for recovering tungsten from causticized slag according to claim 1 or 2, characterized in that: In step (1), the concentration of tungsten ions in the water leaching solution is 1-5 g / L.

4. The method for recovering tungsten from causticized slag according to claim 3, characterized in that: The main component of the causticized slag is calcium carbonate, and the mass percentage of CaCO3 is 90-98%. The mass percentage of sodium tungstate in the form of WO3 in the causticized slag is 0.5-1%.

5. The method for recovering tungsten from causticized slag according to claim 3, characterized in that: In step (2), the pH value of the water extract is adjusted using concentrated sulfuric acid with a mass fraction of 98%.

6. The method for recovering tungsten from causticized slag according to claim 3, characterized in that: The anion exchange resin used in step (2) is a D314 macroporous weakly basic anion exchange resin.

7. The method for recovering tungsten from causticized slag according to claim 3, characterized in that: The tungsten ion concentration in the liquid obtained in step (2) is less than 0.2 g / L, and the liquid is returned to step (1) for leaching the next batch of causticized slag.

8. The method for recovering tungsten from causticized slag according to claim 3, characterized in that: The sodium tungstate solution obtained after the analysis in step (3) is returned to the main process flow of scheelite treatment.

9. The method for recovering tungsten from causticized slag according to claim 3, characterized in that: The concentration of the sodium hydroxide solution used for analysis in step (3) is 1-5 mol / L.

10. The method for recovering tungsten from causticized slag according to claim 3, characterized in that: The water-leached residue obtained in step (1) can be sold as building materials.

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