Low-temperature leaching and hazardous waste treatment method for vanadium and chromium in vanadium-containing raw material

Abstract

The invention discloses a low-temperature leaching and hazardous waste treatment method for vanadium and chromium in a vanadium-containing raw material, and belongs to the crossing field of non-ferrous metal hydrometallurgy and solid waste resource recovery. One or more of sodium hydroxide, potassium hydroxide, sodium carbonate, sodium bicarbonate, sodium percarbonate, potassium percarbonate, potassium carbonate or potassium bicarbonate is adopted as an extracting agent; multi-stage countercurrent extraction is carried out under a low-temperature condition, so that vanadium and chromium metals can be efficiently recovered, and dissolution of impurities such as calcium and magnesium is inhibited. After extraction, tailings are converted into general solid waste, and recycling and harmlessness of hazardous waste are achieved. The method provided by the invention has the advantages of high extraction rate, good selectivity, recyclable extractant, green and environment-friendly process and the like, and solves the technical problems of high vanadium extraction energy consumption, high cost, low purification efficiency, low purity and incapability of recycling hazardous wastes in the prior art.

Description

Technical Field

[0001] This invention relates to the intersection of non-ferrous metal hydrometallurgy and solid waste resource recycling, and in particular to a method for low-temperature leaching of vanadium and chromium from vanadium-containing raw materials and hazardous waste treatment. Background Technology

[0002] Traditional raw materials rely on vanadium-titanium magnetite (accounting for 70% of global vanadium reserves), but high-grade ore resources are becoming increasingly depleted, and a large amount of vanadium-containing raw materials are generated during the smelting process. Meanwhile, the cost of mining low-grade ore is rising, so it is necessary to explore alternative raw material channels. Vanadium mud contains a large amount of unused vanadium and a small amount of chromium. Recycling vanadium mud for reuse can not only reduce resource waste but also create economic benefits.

[0003] Patent 202410222525.3 discloses a method for enhancing vanadium extraction through self-activated roasting and alkaline leaching of vanadium slag. This invention uses calcium oxide and magnesium oxide as roasting additives and utilizes the reaction between calcium and magnesium components and vanadium components to extract vanadium components from vanadium slag. This requires the addition of additives twice, and the additives also need to be treated twice to remove impurities, thus increasing costs and adding excess impurity metals, and they cannot be collected separately. Patent 202511151767.9 discloses a method for acid leaching vanadium extraction from dolomite vanadium slag under negative pressure roasting. This invention uses vanadium slag and dolomite crushed and mixed in a certain proportion, followed by negative pressure roasting and sulfuric acid leaching to extract vanadium. The main components of dolomite are calcium and magnesium carbonate, which not only adds calcium and magnesium ions, but also has high energy consumption due to the negative pressure roasting process, and the roasting process generates a large amount of waste gas.

[0004] Patent 202210902789.4 discloses a method for secondary vanadium extraction from vanadium slag blank or calcified roasted clinker carbonation leaching tailings. This method uses dilute sulfuric acid, sodium carbonate, and sodium bicarbonate as leaching agents to perform secondary vanadium extraction from vanadium slag. The leaching temperature of sodium carbonate or sodium bicarbonate is 90-99℃, which is energy-intensive. Moreover, the leaching solution contains a large number of impurity ions such as calcium, aluminum, and magnesium. Directly adding ammonium bicarbonate to precipitate ammonium metavanadate results in low product purity and makes vanadium precipitation difficult.

[0005] In summary, existing vanadium sludge treatment methods still have some problems. High-temperature roasting and acid leaching consume excessive energy, increasing production costs, generating large amounts of waste gas, and causing environmental pollution. Furthermore, the presence of metals such as calcium, magnesium, and aluminum requires additional treatment, complicating the process. Additionally, chromium in the vanadium sludge is not completely leached, resulting in resource waste and secondary pollution. Secondary vanadium extraction waste residue has a high chromium content, polluting the environment, and incurring high treatment costs, failing to achieve full recovery and utilization of valuable metals and achieve zero emissions. Summary of the Invention

[0006] The purpose of this invention is to provide a method for low-temperature leaching of vanadium and chromium from vanadium-containing raw materials and for the treatment of hazardous waste, thereby solving the technical problems of high energy consumption, high cost, low purification efficiency, low purity, and inability to recycle hazardous waste in the prior art.

[0007] To achieve the above objectives, the present invention provides a method for low-temperature leaching of vanadium and chromium from vanadium-containing raw materials and for hazardous waste treatment, comprising the following steps: S1. Preparation of the extractant; S2. Multi-stage countercurrent extraction: Vanadium-containing raw materials are mixed with extractants in a certain proportion and subjected to continuous multi-stage extraction at a set temperature; S3. Extraction solution treatment and vanadium-chromium separation: Vanadium ions are separated from the final extract solution through subsequent treatment, and chromium-containing solution and regenerated extractant are obtained at the same time; S4. Extractant recycling: The extractant obtained from the regeneration in S3 is returned to the first-stage extraction process in step S2 to achieve the recycling of the extractant.

[0008] Preferably, the vanadium-containing raw material has a dry basis vanadium content of 3-20% and a chromium content of ≤5%.

[0009] Preferably, the extractant in step S1 includes one or more of the following: bases corresponding to sodium and potassium elements, and carbonates, bicarbonates, and percarbonates, including potassium hydroxide, sodium carbonate, sodium bicarbonate, potassium carbonate, sodium percarbonate, potassium percarbonate, potassium bicarbonate, and sodium hydroxide. Specifically, under alkaline conditions, the sodium and potassium soluble salts dissolve to release anions corresponding to vanadium and chromium elements, while carbonate and bicarbonate ions fix polyvalent metal ions.

[0010] Preferably, the concentration of the extract is 0.3-2 mol / L.

[0011] Preferably, in step S2, the solid-liquid ratio of the vanadium-containing raw material to the extract is 1g:(3-15)mL.

[0012] Preferably, in step S2, 2-10 stages of continuous countercurrent extraction are performed at 1-80℃; the extraction time for each stage is 0.5-5 hours; wherein the flow direction of the extractant is opposite to that of the solid material, specifically: S21. In the first stage of extraction, an extractant is used to extract the filter residue from the second stage, and after solid-liquid separation, the final stage filter residue and the first stage filtrate are obtained. S22. In the intermediate nth stage extraction, the filtrate from the (n-1)th stage is used to extract the filter residue from the (n+1)th stage. After solid-liquid separation, the nth stage filter residue and the nth stage filtrate are obtained, and the nth stage filter residue is returned to the previous stage. S23. In the final extraction stage, the filtrate from the previous stage is used to extract the fresh vanadium-containing raw material. After solid-liquid separation, the primary filter residue and the final extract are obtained. The primary filter residue is returned to the previous stage.

[0013] Preferably, the vanadium content in the final filter residue is ≤0.1% and the chromium content is ≤0.005%.

[0014] Preferably, the total leaching rate of calcium, magnesium, silicon and aluminum is ≤0.5%.

[0015] Preferably, the vanadium content in the filter residue is ≤0.1% and the chromium content is ≤0.005%.

[0016] Therefore, the present invention employs the above-mentioned method for low-temperature leaching of vanadium and chromium from vanadium-containing raw materials and for hazardous waste treatment, which has the following beneficial effects: (1) This method can efficiently extract vanadium and chromium from vanadium-containing raw materials, resulting in vanadium content of less than 0.1% and chromium content of less than 0.005% in the tailings, achieving simultaneous high recovery rates of vanadium and chromium. The key lies in the extremely high selectivity of the process for the target metals, which can effectively dissolve vanadium, chromium, sodium, and potassium elements, while suppressing impurities such as calcium, magnesium, aluminum, silicon, and phosphorus in the solid phase, with a leaching rate of ≤0.5%, thereby obtaining an extract with fewer impurities and higher purity, which greatly facilitates subsequent separation and purification. Ultimately, the vanadium-containing raw materials, which were originally hazardous waste, are transformed into general solid waste after extraction, completely realizing the harmlessness and resource utilization of hazardous waste.

[0017] (2) This method uses low-temperature extraction (1-80℃), avoiding the high-temperature roasting step of traditional methods, thus significantly reducing energy consumption. The entire production process generates no waste gas, wastewater, or hazardous waste residue. The extractant can be recycled after regeneration, which not only reduces wastewater discharge and reagent consumption at the source but also achieves clean production throughout the entire process. In addition, this process has good flexibility and adaptability, and is easy to operate continuously and on a large scale. It is not only suitable for vanadium-containing raw materials with complex compositions but can also process various vanadium-chromium-containing raw materials such as vanadium ore.

[0018] (3) This method significantly reduces raw material and processing costs by efficiently recovering vanadium, chromium, sodium and potassium and internally recycling the extractant, thereby further improving the technical and economic efficiency of the process.

[0019] The technical solution of the present invention will be further described in detail below through embodiments. Detailed Implementation

[0020] The technical solution of the present invention will be further described below through embodiments.

[0021] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention pertains.

[0022] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can be appropriately combined to form other embodiments that can be understood by those skilled in the art. These other embodiments are also covered within the scope of protection of this invention.

[0023] Unless otherwise specified, the reagents, instruments, and equipment used in this invention are all commonly used by those skilled in the art, and the testing standards all use national or international standards commonly used in the field, without further explanation.

[0024] Example 1 This embodiment provides a method for low-temperature leaching of vanadium and chromium from vanadium-containing raw materials and for hazardous waste treatment, including the following steps: S1. Preparation of extractant: Dissolve sodium bicarbonate in water to form an extractant solution with a concentration of 1 mol / L.

[0025] S2. Multi-stage countercurrent extraction: The vanadium-containing raw material (vanadium content 3%, chromium content 0.5%) is mixed with the extractant at a solid-liquid ratio of 1:5, stirred at 600 r / min, and subjected to continuous 6-stage extraction at 40℃, with a total extraction time of 3 hours. The specific extraction process includes: S21. First-stage extraction: The filter residue from the second-stage extraction is extracted using an extractant. After solid-liquid separation, the final-stage filter residue and the first-stage filtrate are obtained. The vanadium extraction rate in this stage is 85.2%, and the chromium extraction rate is 90%.

[0026] S22. Second to fifth stage (4 stages in total) extraction: In each stage, the filtrate from the previous stage is used to extract the residue from the next stage. After solid-liquid separation, the residue is returned to the previous stage, and the filtrate enters the next stage.

[0027] S23, Sixth-stage extraction: In the sixth-stage (final-stage) extraction, the fresh vanadium-containing raw material is extracted using the filtrate from the fifth stage. After solid-liquid separation, the primary filter residue and the final-stage extract are obtained. The primary filter residue is returned to the previous stage.

[0028] After the above six-stage extraction process, the total extraction rate of vanadium in the final extract reached 98.7%, the total extraction rate of chromium reached 99.5%, and the total leaching rate of calcium, magnesium, silicon and aluminum was 0.4%; the vanadium content in the final discharged tailings was 0.09% and the chromium content was 0.005%.

[0029] S3. Extraction solution treatment and vanadium-chromium separation: The final extract obtained in S2 is subjected to subsequent treatment (such as organic extraction) to separate vanadium ions, and chromium-containing solution and regenerated extractant are obtained at the same time.

[0030] S4. Extractant recycling: The extractant obtained from the regeneration in S3 is returned to step S21 for the first-stage extraction, thus realizing the recycling of the extractant.

[0031] Example 2 This embodiment provides a method for low-temperature leaching of vanadium and chromium from vanadium-containing raw materials and for hazardous waste treatment, including the following steps: S1. Preparation of extractant: Dissolve potassium carbonate in water to form an extractant solution with a concentration of 0.6 mol / L.

[0032] S2. Multi-stage countercurrent extraction: Vanadium-containing raw material (10% vanadium, 1.5% chromium) is mixed with the extractant at a solid-liquid ratio of 1:9, stirred at 600 r / min, and subjected to continuous four-stage extraction at 30℃ for a total extraction time of 4 hours. The specific extraction process includes: S21, First-stage extraction: The filter residue from the second-stage extraction is extracted using an extractant. After solid-liquid separation, the final-stage filter residue and the first-stage filtrate are obtained. The vanadium extraction rate in this stage is 90.2%, and the chromium extraction rate is 92.2%.

[0033] S22. Second to third stage extraction: In each stage, the filtrate from the previous stage is used to extract the residue from the next stage. After solid-liquid separation, the residue is returned to the previous stage, and the filtrate enters the next stage.

[0034] S23, Fourth stage extraction: Fresh vanadium-containing raw materials are extracted using the filtrate from the third stage. After solid-liquid separation, primary filter residue and final extract are obtained. The primary filter residue is returned to the previous stage.

[0035] After the above four-stage extraction, the vanadium extraction rate in the extract was 99.1%, the chromium extraction rate was 99.8%, the calcium, magnesium, silicon and aluminum extraction rate was 0.5%, and the vanadium content in the tailings was 0.09% and the chromium content was 0.005%.

[0036] S3. Extraction solution treatment and vanadium-chromium separation: The final extract obtained in S2 is subjected to subsequent treatment (such as organic extraction) to separate vanadium ions, and chromium-containing solution and regenerated extractant are obtained at the same time.

[0037] S4. Extractant recycling: The extractant obtained from the regeneration in S3 is returned to step S21 for the first-stage extraction, thus realizing the recycling of the extractant.

[0038] Example 3 This embodiment provides a method for low-temperature leaching of vanadium and chromium from vanadium-containing raw materials and for hazardous waste treatment, including the following steps: S1. Preparation of extractant: Dissolve sodium carbonate and sodium hydroxide in water to form an extractant solution with a concentration of 0.4 mol / L sodium carbonate and 0.2 mol / L sodium hydroxide.

[0039] S2. Multi-stage countercurrent extraction: The vanadium-containing raw material (vanadium content 15%, chromium content 3%) is mixed with the extractant at a solid-liquid ratio of 1:3, stirred at 600 r / min, and subjected to continuous three-stage extraction at 60℃ for a total extraction time of 2 hours. The specific extraction process includes: S21. First-stage extraction: The filter residue from the second-stage extraction is extracted using an extractant. After solid-liquid separation, the final-stage filter residue and the first-stage filtrate are obtained. The first-stage extraction rate of vanadium is 88.2%, and the first-stage extraction rate of chromium is 91.7%.

[0040] S22, Second-stage extraction: The filtrate from the first stage is used to extract the residue from the third stage. After solid-liquid separation, the residue is returned to the first stage, and the filtrate enters the third stage.

[0041] S23, Third-stage extraction: In the third-stage extraction, the filtrate from the second stage is used to extract the fresh vanadium-containing raw material. After solid-liquid separation, the primary filter residue and the final extract are obtained. The primary filter residue is returned to the previous stage.

[0042] After the above three-stage extraction, the vanadium extraction rate in the final extract was 98.9%, the chromium extraction rate was 99.6%, the calcium, magnesium, silicon and aluminum extraction rate was 0.3%, and the tailings contained 0.09% vanadium and 0.005% chromium.

[0043] S3. Extraction solution treatment and vanadium-chromium separation: The final extract obtained in S2 is subjected to subsequent treatment (such as organic extraction) to separate vanadium ions, and chromium-containing solution and regenerated extractant are obtained at the same time.

[0044] S4. Extractant recycling: The extractant obtained from the regeneration in S3 is returned to step S21 for the first-stage extraction, thus realizing the recycling of the extractant.

[0045] Therefore, this invention employs a low-temperature leaching method for vanadium and chromium in vanadium-containing raw materials and a hazardous waste treatment method, solving the problem of hazardous waste treatment generated by existing vanadium slag roasting and leaching processes. It uses one or more of sodium hydroxide, potassium hydroxide, sodium percarbonate, potassium percarbonate, sodium carbonate, sodium bicarbonate, potassium carbonate, or potassium bicarbonate as extractants, and performs multi-stage countercurrent extraction under low-temperature conditions. This method can efficiently recover vanadium and chromium metals while inhibiting the leaching of impurities such as calcium and magnesium. The tailings after extraction are converted into general solid waste, achieving resource utilization and harmless treatment of hazardous waste. This method has advantages such as high extraction rate, good selectivity, recyclable extractants, and a green and environmentally friendly process.

[0046] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for low-temperature leaching of vanadium and chromium from vanadium-containing raw materials and for hazardous waste treatment, characterized in that, Includes the following steps: S1. Preparation of the extractant; S2. Multi-stage countercurrent extraction: Vanadium-containing raw materials are mixed with extractants in a certain proportion and subjected to continuous multi-stage extraction at a set temperature; S3. Extraction solution treatment and vanadium-chromium separation: Vanadium ions are separated from the final extract solution through subsequent treatment, and chromium-containing solution and regenerated extractant are obtained at the same time; S4. Extractant recycling: The extractant obtained from the regeneration in S3 is returned to the first-stage extraction process in step S2 to achieve the recycling of the extractant.

2. The method for low-temperature leaching of vanadium and chromium from vanadium-containing raw materials and hazardous waste treatment according to claim 1, characterized in that, The vanadium-containing raw materials contain 3-20% vanadium on a dry basis and ≤5% chromium.

3. The method for low-temperature leaching of vanadium and chromium from vanadium-containing raw materials and hazardous waste treatment according to claim 1, characterized in that, The extractant is one or more of the following: a soluble alkali corresponding to sodium or potassium, or a soluble carbonate, a soluble bicarbonate, or a soluble percarbonate.

4. The method for low-temperature leaching of vanadium and chromium from vanadium-containing raw materials and hazardous waste treatment according to claim 1, characterized in that, The concentration of the extract is 0.3-2 mol / L.

5. The method for low-temperature leaching of vanadium and chromium from vanadium-containing raw materials and hazardous waste treatment according to claim 1, characterized in that, In step S2, the solid-liquid ratio of the vanadium-containing raw material to the extract is 1g:(3-15)mL.

6. The method for low-temperature leaching of vanadium and chromium from vanadium-containing raw materials and hazardous waste treatment according to claim 1, characterized in that, In step S2, continuous countercurrent extraction of 2-10 stages is performed at 1-80℃, with each stage lasting 0.5-5 hours; wherein the flow direction of the extractant is opposite to that of the solid material, specifically: S21. In the first stage of extraction, an extractant is used to extract the filter residue from the second stage, and after solid-liquid separation, the final stage filter residue and the first stage filtrate are obtained. S22. In the intermediate nth stage extraction, the filtrate from the (n-1)th stage is used to extract the filter residue from the (n+1)th stage. After solid-liquid separation, the nth stage filter residue and the nth stage filtrate are obtained, and the nth stage filter residue is returned to the previous stage. S23. In the final extraction stage, the filtrate from the previous stage is used to extract the fresh vanadium-containing raw material. After solid-liquid separation, the primary filter residue and the final extract are obtained. The primary filter residue is returned to the previous stage.

7. The method for low-temperature leaching of vanadium and chromium from vanadium-containing raw materials and hazardous waste treatment according to claim 6, characterized in that, The vanadium content in the final filter residue is ≤0.1%, and the chromium content is ≤0.005%.

8. The method for low-temperature leaching of vanadium and chromium from vanadium-containing raw materials and hazardous waste treatment according to claim 1, characterized in that, The total leaching rate of calcium, magnesium, silicon and aluminum is ≤0.5%.