Converter vanadium slag gypsum negative pressure roasting circulation process

Abstract

The invention discloses a converter vanadium slag gypsum negative pressure roasting circulation process, and relates to the technical field of non-ferrous metal solid waste diversified utilization, the method comprises the following steps: mixing raw materials according to a ratio, and carrying out negative pressure roasting to obtain calcified slag and sulfur dioxide, the raw materials comprising converter vanadium slag and industrial waste gypsum; industrial waste gypsum and converter vanadium slag are used as raw materials, roasting is performed under negative pressure, secondary countercurrent leaching is performed to obtain vanadium-containing acid leaching liquid, and the vanadium-containing acid leaching liquid is subjected to purification and impurity removal to directly prepare the vanadyl sulfate electrolyte. Wherein sulfur dioxide gas generated in the roasting process is directly used for preparing acid for acid leaching, leaching residues can be prepared into an adsorbent for pretreatment of vanadium-containing leaching liquid, multi-component cyclic utilization is achieved, and the cost is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of diversified utilization of non-ferrous metal solid waste, and particularly relates to a converter vanadium slag gypsum negative pressure roasting circulating process. BACKGROUND

[0002] Vanadium is known as "modern industrial vitamin", and is an indispensable strategic resource for developing modern industry, national defense and new energy technology, and is widely used in the fields of steel, aerospace, chemical industry, medical treatment and energy storage. With the rapid development of electrochemical energy storage industry, vanadium flow battery has the advantages of large capacity, high efficiency and good safety, and is widely used in the fields of new energy power generation and smart grid construction, so vanadium has become a necessity for long-term stable new energy storage industry, and is known as "new energy storage metal". Converter vanadium slag is the product extracted from vanadium molten iron in the converter steelmaking process, and contains rich vanadium elements, which is one of the important vanadium resources in China. At present, the sodium roasting vanadium extraction process is the most mature vanadium extraction process in industry. However, a large amount of sodium-containing wastewater and waste gas will be produced in the sodium roasting process, and the waste gas contains harmful gases such as HCl and Cl2, which causes serious pollution to the environment. Compared with sodium roasting, calcium roasting can effectively reduce the emission of harmful gases and alkaline tailings, and is a clean process that can replace the traditional sodium vanadium extraction process, but the calcium roasting has problems such as high roasting temperature, high energy consumption and low vanadium extraction efficiency. Therefore, the "gypsum negative pressure roasting calcium vanadium extraction" technology is developed to effectively reduce the energy consumption of vanadium extraction, desulfurization gypsum consumption and high-quality vanadium sulfate oxide short process preparation.

[0003] Publication No. CN113998735B discloses a method for producing vanadium sulfate oxide battery electrolyte by using vanadium-containing acid leaching solution. The method needs to add a reducing agent to the vanadium-containing acid leaching solution for reduction reaction, and after the reaction is completed, the pH is adjusted to 1.5-4.0, and the extraction circulation process is carried out. This method reduces the preparation of intermediate product vanadium pentoxide, but needs to add a reducing agent for reduction and then extract to prepare vanadium sulfate oxide, which increases the cost. Therefore, a method for directly preparing vanadium sulfate oxide by negative pressure roasting of converter vanadium slag is proposed. SUMMARY

[0004] (I) Technical problem to be solved

[0005] In view of the above-mentioned shortcomings and deficiencies of the prior art, the present application provides a converter vanadium slag gypsum negative pressure roasting circulating process, which solves the technical problems proposed in the above background.

[0006] (II) Technical scheme

[0007] In order to achieve the above-mentioned purposes, the main technical scheme adopted by the present application comprises:

[0008] The converter vanadium slag gypsum negative pressure roasting circulating process provided by the embodiment of the present application comprises:

[0009] 1) The raw materials are mixed in proportion and then roasted under negative pressure to obtain calcified slag and sulfur dioxide. The raw materials include converter vanadium slag and industrial waste gypsum.

[0010] 2) Leach the calcified slag with a leaching agent, and at the same time add sulfur dioxide to the calcified slag to replenish it, so as to obtain vanadium-containing leachate and leaching slag.

[0011] 3) Adjust the pH value of the vanadium-containing leachate to obtain filtrate and CaSO4; wherein the CaSO4 is recovered and used as the raw material in step 1).

[0012] 4) Pass the sulfur dioxide from step 1) into the filtrate to reduce pentavalent vanadium to tetravalent vanadium;

[0013] 5) Extract the filtrate with an organic extractant to obtain an organic phase and an aqueous phase loaded with vanadium. Then, back-extract the organic phase with sulfuric acid to obtain vanadium oxysulfate and raffinate. The raffinate is recovered and used as the leaching agent in step 2).

[0014] Optionally, in step 1), the industrial waste gypsum includes one or more of desulfurized gypsum, phosphogypsum, fluorogypsum, and citric acid gypsum.

[0015] Optionally, in step 1), the step of subjecting the raw materials to negative pressure roasting to obtain calcified slag and sulfur dioxide further includes:

[0016] Industrial waste gypsum and converter vanadium slag are mixed at a ratio of n(CaSO4) / n(V2O3) of 0.2-5.0, and calcined at a vacuum of 0.01-1 atm and a temperature of 400-900℃ for 0.5-4 hours to obtain calcified slag and sulfur dioxide.

[0017] Optionally, the step of leaching the calcified slag with a leaching agent in step 2) to obtain a vanadium-containing leachate and leaching residue further includes:

[0018] The leaching agent is sulfuric acid. The calcified slag is leached with the leaching agent at a temperature of 20-100℃ and a leaching time of 30-180 min to obtain vanadium-containing leachate and leaching slag.

[0019] Optionally, in step 4), the step of passing sulfur dioxide from step 1) into the filtrate to reduce pentavalent vanadium to tetravalent vanadium further includes:

[0020] Sulfur dioxide is introduced into the leachate at a flow rate of 0.5-5 L / min, and the reduction reaction lasts for 0.5-3 h, reducing pentavalent vanadium to tetravalent vanadium.

[0021] Optionally, in step 5), the step of extracting the filtrate with an organic extractant to obtain a vanadium-loaded organic phase and an aqueous phase, and then back-extracting the organic phase with sulfuric acid to obtain vanadium oxysulfate and raffinate further includes:

[0022] The filtrate is extracted with an organic extractant, with the volume ratio of organic phase to aqueous phase between 1:1 and 5:1, and the number of extraction stages is 3 to 10. Then, it is back-extracted with a sulfuric acid solution with a concentration of 1-5 mol / L at a temperature of 25-50℃ for 15-60 min to obtain a vanadium oxysulfate electrolyte.

[0023] The organic extractant is one or both of P204 and P507.

[0024] Optionally, the reduction endpoint can be controlled by detecting changes in the vanadium valence state.

[0025] Optionally, the back-extraction step using a sulfuric acid solution with a concentration of 1-5 mol / L further includes:

[0026] The vanadium oxysulfate obtained after back-extraction has a purity of ≥99%.

[0027] (III) Beneficial Effects

[0028] The beneficial effects of this invention are as follows: This invention provides a negative pressure roasting and circulating process for converter vanadium slag gypsum, using industrial waste gypsum and converter vanadium slag as raw materials. After roasting under negative pressure, a secondary countercurrent leaching is performed to obtain a vanadium-containing acid leaching solution. The vanadium-containing leaching solution is then purified to directly prepare vanadium oxysulfate electrolyte. The sulfur dioxide gas generated during the roasting process is directly used to produce acid for acid leaching. This method uses converter vanadium slag and industrial waste gypsum as raw materials, achieving high-value utilization of converter vanadium slag while reducing production costs and energy consumption. It achieves emission reduction, energy saving, green production, and efficient preparation of vanadium oxysulfate electrolyte, overcoming the shortcomings of existing technologies. It utilizes industrial waste gypsum resourcefully and achieves direct reduction to prepare vanadium oxysulfate electrolyte, simplifying the process flow, reducing production costs, realizing high-value utilization of converter vanadium slag, and promoting industrialization. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the process flow of a converter vanadium slag gypsum negative pressure roasting and circulation process according to the present invention. Detailed Implementation

[0030] To better explain and facilitate understanding of the present invention, the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0031] To better understand the above technical solutions, exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that the present invention can be understood more clearly and thoroughly, and that the scope of the present invention can be fully conveyed to those skilled in the art.

[0032] Reference Figure 1 This embodiment provides a negative pressure roasting and circulation process for vanadium slag gypsum in a converter, the method including:

[0033] 1) The raw materials are mixed in proportion and then roasted under negative pressure to obtain calcified slag and sulfur dioxide. The raw materials include converter vanadium slag and industrial waste gypsum.

[0034] In step 1), industrial waste gypsum includes one or more of desulfurized gypsum, phosphogypsum, fluorogypsum, and citric acid gypsum;

[0035] Industrial waste gypsum and converter vanadium slag are mixed at a ratio of n(CaSO4) / n(V2O3) of 0.2-5.0, and calcined at a vacuum of 0.01-1 atm and a temperature of 400-900℃ for 0.5-4 hours to obtain calcified slag and sulfur dioxide.

[0036] The sulfur dioxide obtained from the negative pressure roasting is used in two ways: firstly, as a reducing agent, it reacts with the vanadium component in the filtrate obtained after pH adjustment to reduce high-valence vanadium to VOCs. 2- The amount of sulfur dioxide added for this portion is: sulfur dioxide: VO (based on the stoichiometric coefficients of the reduction chemical reaction) 2+ (1:2~1.5:2) is added, and the remaining part is used as raw material for sulfuric acid preparation. The obtained sulfuric acid is used to supplement the sulfuric acid used for acid leaching of calcified slag.

[0037] The reaction equation is:

[0038] 2) Leach the calcified slag with a leaching agent, and at the same time add sulfur dioxide to the calcified slag to replenish it, so as to obtain vanadium-containing leachate and leaching slag.

[0039] In step 2), sulfuric acid is used as the leaching agent to leach the calcified slag. The leaching temperature is 20-100℃ and the leaching time is 30-180 min, resulting in a vanadium-containing leachate and leaching slag.

[0040] 3) Adjust the pH value of the vanadium-containing leachate to obtain filtrate and CaSO4; wherein the CaSO4 is recovered and used as the raw material in step 1).

[0041] 4) Pass the sulfur dioxide from step 1) into the filtrate to reduce pentavalent vanadium to tetravalent vanadium;

[0042] Sulfur dioxide was introduced into the vanadium-containing leaching solution at a flow rate of 0.5-5 L / min to ensure sufficient contact and reaction between the sulfur dioxide and the vanadium-containing leaching solution. The reduction reaction lasted for 0.5-3 hours, reducing pentavalent vanadium to tetravalent vanadium. The progress of the reduction reaction was determined by detecting the change in the valence state of vanadium in the reaction system.

[0043] 5) Extract the filtrate with an organic extractant to obtain an organic phase and an aqueous phase loaded with vanadium. Then, back-extract the organic phase with sulfuric acid to obtain vanadium oxysulfate and raffinate. The raffinate is recovered and used as the leaching agent in step 2).

[0044] In step 5), the vanadium-containing leachate is extracted with an organic extractant. The extraction process is carried out in a separatory funnel or extraction tower. The volume ratio of the organic phase to the aqueous phase is between 1:1 and 5:1, and the number of extraction stages is 3-10. Multiple extractions achieve efficient separation of vanadium from impurity elements. After extraction, a 1-5 mol / L sulfuric acid solution is used for back-extraction at a temperature of 25-50℃ for 15-60 minutes to obtain vanadium oxysulfate electrolyte. The purity of the prepared vanadium oxysulfate electrolyte is tested using chemical analysis, spectral analysis, and other methods to detect the vanadium content and impurity element content in the crystals, ensuring that the product meets the relevant standards for vanadium oxysulfate electrolyte and has a purity of over 99%.

[0045] The organic extractant is one or both of P204 and P507;

[0046] Wastewater, waste residue, and other waste generated during the entire preparation process must be treated to render them harmless. Wastewater is treated through processes such as neutralization, sedimentation, and filtration to meet discharge standards before being discharged. Waste residue is comprehensively utilized or safely landfilled, thus achieving a green and environmentally friendly entire preparation process.

[0047] Example 1

[0048] Vanadium slag from a converter and fluorogypsum were selected as raw materials, with fluorogypsum added at a rate of 2.0%. The negative pressure vacuum was maintained at -0.02 MPa, and the mixture was calcined at 700℃ for 1.5 h to obtain calcified vanadium slag. In the leaching process, sulfuric acid and citric acid were used as leaching agents, with a leaching time of 60 min and a leaching temperature of 80℃ to obtain a vanadium-containing leachate. Sulfur dioxide generated during calcination was introduced into the vanadium-containing leachate at a flow rate of 4 L / min for a reduction time of 1 h. P2O4 was used as the extractant in the extraction tower, with a ratio controlled at 4:1 and 7 extraction stages. A 4 mol / L sulfuric acid solution was used as the back-extraction agent, with a back-extraction time of 20 min and a back-extraction temperature controlled at 45℃ to obtain a high-concentration vanadium oxysulfate solution.

[0049] Example 2

[0050] Using converter vanadium slag and citric acid gypsum as raw materials, with citric acid gypsum added at a rate of 0.5%, and a negative pressure vacuum of -0.04 MPa, calcination was carried out at 450℃ for 3.5 h to obtain calcified vanadium slag. Hydrochloric acid and phosphoric acid were selected as leaching agents, with a leaching time of 150 min and a leaching temperature of 30℃ to obtain vanadium-containing leachate. Sulfur dioxide was introduced into the vanadium-containing leachate at a flow rate of 1 L / min, and the reduction duration was 2.5 h. P507 was selected as the extractant, and extraction was carried out in a separatory funnel with a ratio of 1.5:1 and 4 extraction stages. The concentration of sulfuric acid solution as the back-extraction agent was 1.5 mol / L, the back-extraction time was 50 min, and the back-extraction temperature was 30℃ to obtain vanadium oxysulfate electrolyte.

[0051] Example 3

[0052] The raw material is a mixture of converter vanadium slag, desulfurized gypsum, and phosphogypsum, with a total volume of 1.2. The ratio of desulfurized gypsum to phosphogypsum is 1:1. The negative pressure vacuum degree is -0.06 MPa, and the mixture is calcined at 550℃ for 2 hours to obtain calcified vanadium slag. A mixed acid of sulfuric acid, hydrochloric acid, and citric acid is used as the leaching agent. The leaching time is 100 min, and the leaching temperature is 70℃ to obtain a vanadium-containing leachate. Sulfur dioxide is introduced into the vanadium-containing leachate at a flow rate of 2.5 L / min, and the reduction time is 1.8 h. A mixed extractant of P204 and P507 is selected and extracted in an extraction tower with a ratio of 2.5:1 and 8 extraction stages. The back-extraction agent is a sulfuric acid solution with a concentration of 3.5 mol / L. The back-extraction time is 35 min, and the back-extraction temperature is 42℃ to obtain a vanadium oxysulfate solution.

[0053] Example 4

[0054] Using a mixture of vanadium slag from a converter and waste gypsum consisting of fluorogypsum and citric acid gypsum as raw materials, with a total amount of 2.5 and a ratio of fluorogypsum to citric acid gypsum of 3:2, and a negative pressure vacuum of -0.04 MPa, calcination was carried out at 650℃ for 1 h to obtain calcified vanadium slag. Phosphoric acid and sulfuric acid were used as leaching agents, with a leaching time of 40 min and a leaching temperature of 90℃ to obtain a vanadium-containing leachate. Sulfur dioxide was introduced into the vanadium-containing leachate at a flow rate of 3.5 L / min for a reduction time of 0.8 h. P507 was selected as the extractant, and extraction was carried out in a separatory funnel with a ratio of 3.5:1 and 9 extraction stages. The sulfuric acid solution concentration of the back-extraction agent was 4.5 mol / L, the back-extraction time was 18 min, and the back-extraction temperature was 48℃ to obtain a vanadium oxysulfate solution.

[0055] In the description of this invention, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0056] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, then this invention should also include these modifications and variations.

[0057] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make modifications, alterations, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A negative pressure roasting and circulating process for vanadium slag gypsum in a converter, characterized in that, The method includes: 1) The raw materials are mixed in proportion and then roasted under negative pressure to obtain calcified slag and sulfur dioxide. The raw materials include converter vanadium slag and industrial waste gypsum. 2) Leach the calcified slag with a leaching agent, and at the same time add sulfur dioxide to the calcified slag to replenish it, so as to obtain vanadium-containing leachate and leaching slag. 3) Adjust the pH value of the vanadium-containing leachate to obtain filtrate and CaSO4; wherein the CaSO4 is recovered and used as the raw material in step 1). 4) Pass the sulfur dioxide from step 1) into the filtrate to reduce pentavalent vanadium to tetravalent vanadium; 5) Extract the filtrate with an organic extractant to obtain an organic phase and an aqueous phase loaded with vanadium. Then, back-extract the organic phase with sulfuric acid to obtain vanadium oxysulfate and raffinate. The raffinate is recovered and used as the leaching agent in step 2).

2. The converter vanadium slag gypsum negative pressure roasting and circulation process as described in claim 1, characterized in that: In step 1), industrial waste gypsum includes one or more of desulfurized gypsum, phosphogypsum, fluorogypsum, and citric acid gypsum.

3. The converter vanadium slag gypsum negative pressure roasting and circulation process as described in claim 1, characterized in that, In step 1), the step of subjecting the raw materials to negative pressure roasting to obtain calcified slag and sulfur dioxide further includes: Industrial waste gypsum and converter vanadium slag are mixed at a ratio of n(CaSO4) / n(V2O3) of 0.2-5.0, and calcined at a vacuum of 0.01-1 atm and a temperature of 400-900℃ for 0.5-4 hours to obtain calcified slag and sulfur dioxide.

4. The converter vanadium slag gypsum negative pressure roasting and circulation process as described in claim 1, characterized in that, In step 2), the step of leaching the calcified slag with a leaching agent to obtain a vanadium-containing leachate and leaching residue further includes: The leaching agent is sulfuric acid. The calcified slag is leached with the leaching agent at a temperature of 20-100℃ and a leaching time of 30-180 min to obtain vanadium-containing leachate and leaching slag.

5. The converter vanadium slag gypsum negative pressure roasting and circulation process as described in claim 1, characterized in that, In step 4), the sulfur dioxide from step 1) is passed into the filtrate to reduce pentavalent vanadium to tetravalent vanadium, which further includes: Sulfur dioxide is introduced into the leachate at a flow rate of 0.5-5 L / min, and the reduction reaction lasts for 0.5-3 h, reducing pentavalent vanadium to tetravalent vanadium.

6. The converter vanadium slag gypsum negative pressure roasting and circulation process as described in claim 1, characterized in that, In step 5), the step of extracting the filtrate with an organic extractant to obtain a vanadium-loaded organic phase and an aqueous phase, and then back-extracting the organic phase with sulfuric acid to obtain vanadium oxysulfate and raffinate further includes: The filtrate is extracted with an organic extractant, with the volume ratio of organic phase to aqueous phase between 1:1 and 5:1, and the number of extraction stages is 3 to 10. Then, it is back-extracted with a sulfuric acid solution with a concentration of 1-5 mol / L at a temperature of 25-50℃ for 15-60 min to obtain a vanadium oxysulfate electrolyte. The organic extractant is one or both of P204 and P507.

7. A converter vanadium slag gypsum negative pressure roasting and circulation process as described in claim 1 or 5, characterized in that: The reduction endpoint is controlled by detecting changes in the vanadium valence state.

8. The negative pressure roasting and circulating process for vanadium slag gypsum in a converter as described in claim 6, characterized in that: The back-extraction step using a 1-5 mol / L sulfuric acid solution also includes: The purity of the vanadium oxysulfate obtained after back-extraction is ≥99%.

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