Compound additive for roasting vanadium slag and application of compound additive in extracting vanadium from vanadium slag

Abstract

The invention relates to the technical field of vanadium metallurgy, and provides a compound additive for roasting vanadium slag and application of the compound additive in extracting vanadium from the vanadium slag. The invention relates to a compound additive for roasting vanadium slag. The compound additive comprises the following components: gypsum powder and Mn (OH) 2, the mass ratio of Mn (OH) 2 to calcium sulfate in the gypsum powder is (0.1-0.3): 1; in the process of extracting vanadium from the vanadium slag, the vanadium-containing solution is subjected to vanadium precipitation, and ammonium metavanadate and wastewater are obtained; neutralizing the wastewater to obtain purified water, gypsum and Mn (OH) 2; the purified water is recycled for leaching or vanadium precipitation, and gypsum and Mn (OH) 2 are recycled as components of the composite additive. Through the technical scheme, the problem that in the prior art, the recovery rate of vanadium is insufficient when an auxiliary is applied to vanadium extraction of vanadium slag is solved, meanwhile, cyclic utilization of the auxiliary is achieved, and unit consumption of the auxiliary is greatly reduced.

Description

Technical Field

[0001] This invention relates to the field of vanadium metallurgy technology, specifically to a composite additive for vanadium slag roasting and its application in vanadium extraction from vanadium slag. Background Technology

[0002] Currently, the mainstream processes for producing vanadium pentoxide from vanadium slag are the sodium leaching method and the calcification method. The sodium leaching method involves grinding vanadium slag, adding sodium salts, and roasting. The resulting clinker is then leached with water to obtain vanadium liquor, which precipitates to form ammonium polyvanadate. However, the wastewater from the precipitation cannot be directly discharged and requires specialized water treatment. Therefore, while the sodium leaching method is mature, its water treatment process is complex and costly. The calcification method also involves grinding vanadium slag, adding limestone for roasting, leaching with dilute sulfuric acid to obtain vanadium liquor, and finally precipitating the liquor. The precipitated wastewater can be neutralized with lime and then returned to the leaching process. The calcification method has the advantages of less wastewater and lower cost, but it consumes a large amount of calcium-based additives such as limestone and produces a large amount of gypsum sludge as a byproduct, thus affecting production cost control. Therefore, it is necessary to design an additive for vanadium extraction from vanadium slag to improve the vanadium recovery rate and achieve green and efficient recovery. Summary of the Invention

[0003] This invention proposes a composite additive for vanadium slag roasting and its application in vanadium extraction from vanadium slag, solving the problem of insufficient vanadium recovery rate in the application of additives to vanadium extraction from vanadium slag in related technologies.

[0004] The technical solution of the present invention is as follows: This invention proposes a composite additive for vanadium slag roasting, comprising the following components: gypsum powder and Mn(OH)2; The mass ratio of Mn(OH)2 to calcium sulfate in gypsum powder is 0.1~0.3:1.

[0005] As a further technical solution, the method for preparing gypsum powder includes the following steps: drying and crushing gypsum to obtain gypsum powder.

[0006] As a further technical solution, the particle size of the gypsum powder is 50~200 mesh.

[0007] As a further technical solution, the mass ratio of Mn(OH)2 to calcium sulfate in gypsum powder is 0.15~0.2:1.

[0008] In the process of vanadium extraction from vanadium slag, this invention further limits the mass ratio of Mn(OH)2 to calcium sulfate in gypsum powder to 0.15~0.2:1. When the proportion of Mn(OH)2 is low, the amount of MnO generated is insufficient, which cannot fully catalyze the oxidation reaction of vanadium, resulting in a decrease in vanadium conversion efficiency and limited improvement in recovery rate. Excessive MnO affects the reaction between calcium sulfate decomposition products and vanadium slag, forming compounds with vanadium that are difficult to leach, which is not conducive to improving the vanadium recovery rate.

[0009] As a further technical solution, the application of the composite additive for vanadium slag roasting in vanadium slag extraction includes the following steps: S1. The vanadium slag is crushed and ball-milled to produce vanadium slag powder; the vanadium slag powder is then magnetically separated to obtain refined vanadium slag powder and iron concentrate. S2. Mix the refined vanadium slag powder and the composite additive to obtain a mixture; S3. The mixture is calcined and ball-milled to obtain a fine powder. S4. The mixed fine powder is added to an acid solution for leaching to obtain a vanadium-containing solution; vanadium is precipitated from the vanadium-containing solution to obtain ammonium metavanadate and wastewater; S5. The wastewater is neutralized to obtain purified water, gypsum and Mn(OH)2; the purified water is reused in the leaching or vanadium precipitation in step S4, and the gypsum and Mn(OH)2 are recovered as components of the composite additive. S6. The ammonium metavanadate is dried, calcined, and melted to produce V2O5.

[0010] As a further technical solution, the particle size of the vanadium slag powder is 50~200 mesh.

[0011] As a further technical solution, the particle size of the mixed fine powder is 100~500 mesh.

[0012] As a further technical solution, the mass ratio of vanadium in the refined vanadium slag powder to the mass ratio of the composite additive is 1:0.3~0.5.

[0013] In the process of vanadium extraction from vanadium slag, the vanadium recovery rate is further improved when the mass ratio of vanadium to composite additive in refined vanadium slag powder is 1:0.3~0.5. If the proportion of composite additive is too low, the amount of alkaline substances and reducing gases produced by the decomposition of gypsum powder and the amount of MnO generated by the decomposition of Mn(OH)2 are insufficient, making it difficult for vanadium to be converted into a more easily extracted state, thus resulting in a lack of significant improvement in vanadium recovery rate. On the other hand, if the proportion of composite additive is too high, excessive composite additive will introduce impurities into the roasting system, which will coat vanadium particles and hinder the diffusion and migration of vanadium, which is also not conducive to vanadium recovery.

[0014] As a further technical solution, the calcination process has a throughput of 10~50 t / h, a temperature of 300~1000℃, a time of 240~440 min, and an oxygen flow rate of 10~50 L / min.

[0015] As a further technical solution, the roasting includes a first stage roasting, a second stage roasting, and a third stage roasting.

[0016] As a further technical solution, the first stage of roasting is carried out by heating to 300-600℃ at a rate of 10-15℃ / min for 60-120min.

[0017] As a further technical solution, the second stage of roasting is carried out by heating to 610-750℃ at a rate of 10-15℃ / min for 120-200min.

[0018] As a further technical solution, the third stage of calcination involves heating to 760-1000℃ at a rate of 10-15℃ / min for 60-120min.

[0019] In the vanadium extraction process from vanadium slag, this invention employs segmented roasting. At lower temperatures, the composite additives fully contact and initially react with the vanadium slag. As the temperature rises to the intermediate temperature stage, the reaction between the composite additives and the vanadium slag intensifies. In the final high-temperature stage, the remaining unreacted vanadium compounds are further transformed, and secondary reactions occur between the various substances generated in the early stages, ensuring that vanadium is extracted more efficiently during the leaching process.

[0020] As a further technical solution, the acid solution includes a dilute sulfuric acid solution.

[0021] As a further technical solution, the mass concentration of the dilute sulfuric acid solution is 10%~50%, and the temperature is 50~90℃.

[0022] As a further technical solution, the volume concentration of the vanadium-containing solution is 2~30 g / L.

[0023] As a further technical solution, the vanadium precipitation includes the following steps: adding sulfuric acid solution and ammonium sulfate solution to the vanadium-containing solution to adjust the pH to 1-3, and performing a precipitation reaction.

[0024] As a further technical solution, the mass concentration of the sulfuric acid solution is 10%~50%.

[0025] As a further technical solution, the precipitation reaction is carried out at a temperature of 80~100℃ for a time of 45~95min.

[0026] As a further technical solution, the mass ratio of the vanadium-containing solution to ammonium sulfate is 100:1.0~5.0.

[0027] As a further technical solution, the leaching includes primary leaching and secondary leaching.

[0028] As a further technical solution, the pH value of the primary leaching is 3-5.

[0029] As a further technical solution, the first-stage leaching time is 40-55 minutes.

[0030] As a further technical solution, the pH value of the secondary leaching is 1~2.

[0031] As a further technical solution, the secondary leaching time is 2-6 minutes.

[0032] As a further technical solution, in step S5, the treatment process includes the following steps: adding FeSO4 to the wastewater, performing a reduction reaction, and then adding lime until the pH of the wastewater reaches 8-11.

[0033] As a further technical solution, the reduction reaction time is 15~25 min.

[0034] As a further technical solution, the amount of FeSO4 added is 1~20 kg / m³. 3 .

[0035] As a further technical solution, the drying temperature is 100~200℃ and the time is 6~8h.

[0036] As a further technical solution, the calcination temperature is 400~600℃ and the time is 2.5~3.5h.

[0037] As a further technical solution, the melting temperature is 750~1000℃ and the time is 5~10min.

[0038] The working principle and beneficial effects of this invention are as follows: In this invention, gypsum powder and Mn(OH)2 are used as a composite additive for vanadium slag roasting, which significantly improves the recovery rate of vanadium extraction from vanadium slag. The alkaline substances and reducing gases produced by the decomposition of gypsum powder provide a more favorable reaction environment for MnO generated by the decomposition of Mn(OH)2, enhancing the catalytic activity of MnO. Furthermore, the catalytic effect of MnO can promote various reactions in vanadium slag, enabling the substances produced by the decomposition of gypsum powder to react more effectively with the components of vanadium slag, thereby improving the vanadium recovery rate. The gypsum and Mn(OH)2 recovered from the wastewater can be recycled, which greatly reduces the consumption of additives in the rotary kiln, and at the same time, V(OH)4 carried away from the waste sludge can be recovered. Attached Figure Description

[0039] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0040] Figure 1 This is a physical image of V2O5 in Embodiment 3 of the present invention; Figure 2 This is a flowchart of the vanadium slag roasting process of the present invention. Detailed Implementation

[0041] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0042] In the following embodiments and comparative examples, The composition of vanadium slag includes: V2O5: 15.29 wt%, T Fe : 31.00wt%, TiO2: 14.38wt%, SiO2: 14.50wt%, MnO: 7.32wt%, CaO: 2.57wt%, MgO: 2.92wt%, Al2O3: 3.47wt%, Cr2O3: 1.43wt%; The composition of gypsum includes: CaSO4·2H2O: 93.2 wt%.

[0043] Example 1 A composite additive for vanadium slag roasting comprises the following components: gypsum powder and Mn(OH)2; The mass ratio of Mn(OH)2 to calcium sulfate in gypsum powder is 0.1:1; The method for preparing gypsum powder includes the following steps: drying gypsum at 100℃ for 12 hours, crushing it, and obtaining 50-mesh gypsum powder; The application of composite additives for vanadium slag roasting in vanadium slag vanadium extraction includes the following steps: S1. Crush and ball-mill the vanadium slag to produce vanadium slag powder with a mesh size of 50; then magnetically separate the vanadium slag powder to obtain refined vanadium slag powder and iron concentrate. S2. Mix the refined vanadium slag powder and the composite additive (the mass ratio of vanadium in the refined vanadium slag powder to the mass ratio of the composite additive is 1:0.7) to obtain the mixture; S3. The mixture is first heated to 300℃ at 10℃ / min and calcined for 440min. The calcination capacity is 10t / h and the oxygen flow rate during calcination is 10L / min. The mixture is then cooled down in the furnace and ball-milled to obtain a 100-mesh fine powder. S4. Add a 10% sulfuric acid solution at 50℃ to the mixed fine powder for two-stage leaching. The pH value of the first leaching is 3, and the leaching time is 40 min. The pH value of the second leaching is 1, and the leaching time is 2 min, to obtain a vanadium-containing solution with a volume concentration of 2 g / L. Add a 10% sulfuric acid solution and ammonium sulfate to the vanadium-containing solution to adjust the pH value to 3. Settle the vanadium at 80℃ for 95 min (the mass ratio of vanadium-containing solution to ammonium sulfate is 100:1.0) to obtain ammonium metavanadate and wastewater. S5. Add FeSO4 to the wastewater (the amount of FeSO4 added is 1 kg / m³). 3 After reducing for 25 minutes, lime is added to adjust the pH of the wastewater to 8, resulting in purified water, gypsum, and Mn(OH)2. The purified water is returned to the leaching or vanadium precipitation process in step S4, and the gypsum and Mn(OH)2 are used to form a composite additive. S6. Dry ammonium metavanadate at 100℃ for 8 hours, then calcine it at 400℃ for 3.5 hours at a heating rate of 10℃ / min, and finally melt it at 750℃ for 10 minutes to obtain V2O5.

[0044] Example 2 A composite additive for vanadium slag roasting comprises the following components: gypsum powder and Mn(OH)2; The mass ratio of Mn(OH)2 to calcium sulfate in gypsum powder is 0.3:1; The method for preparing gypsum powder includes the following steps: drying gypsum at 100℃ for 12 hours, crushing it, and obtaining 200-mesh gypsum powder; The application of composite additives for vanadium slag roasting in vanadium slag vanadium extraction includes the following steps: S1. Crush and ball-mill the vanadium slag to produce vanadium slag powder of 200 mesh; magnetically separate the vanadium slag powder to obtain refined vanadium slag powder and iron concentrate. S2. Mix the refined vanadium slag powder and the composite additive (the mass ratio of vanadium in the refined vanadium slag powder to the mass ratio of the composite additive is 1:0.7) to obtain the mixture; S3. The mixture is first heated to 1000℃ at 15℃ / min and calcined for 240min. The calcination capacity is 50t / h and the oxygen flow rate during calcination is 50L / min. The mixture is then cooled down in the furnace and ball-milled to obtain a 500-mesh fine powder. S4. Add a 50% sulfuric acid solution at 90℃ to the mixed fine powder for two-stage leaching. The first-stage leaching has a pH of 5 and lasts for 55 minutes, while the second-stage leaching has a pH of 2 and lasts for 6 minutes, resulting in a vanadium-containing solution with a volume concentration of 30 g / L. Add a 50% sulfuric acid solution and ammonium sulfate to the vanadium-containing solution to adjust the pH to 1, and precipitate vanadium at 80℃ for 95 minutes (the mass ratio of vanadium-containing solution to ammonium sulfate is 100:5.0), resulting in ammonium metavanadate and wastewater. S5. Add FeSO4 to the wastewater (the amount of FeSO4 added is 20 kg / m³). 3 After reducing for 15 minutes, lime is added to adjust the pH of the wastewater to 11, resulting in purified water, gypsum, and Mn(OH)2. The purified water is returned to the leaching or vanadium precipitation process in step S4, and the gypsum and Mn(OH)2 are used to form a composite additive. S6. Dry ammonium metavanadate at 200℃ for 6 hours, then calcine it at 600℃ for 3.5 hours at a heating rate of 10℃ / min, and finally melt it at 1000℃ for 5 minutes to obtain V2O5.

[0045] Example 3 A composite additive for vanadium slag roasting comprises the following components: gypsum powder and Mn(OH)2; The mass ratio of Mn(OH)2 to calcium sulfate in gypsum powder is 0.25:1; The method for preparing gypsum powder includes the following steps: drying gypsum at 100℃ for 12 hours, crushing it, and obtaining 150-mesh gypsum powder; The application of composite additives for vanadium slag roasting in vanadium slag vanadium extraction includes the following steps: S1. Crush and ball-mill the vanadium slag to produce vanadium slag powder of 150 mesh; magnetically separate the vanadium slag powder to obtain refined vanadium slag powder and iron concentrate. S2. Mix the refined vanadium slag powder and the composite additive (the mass ratio of vanadium in the refined vanadium slag powder to the mass ratio of the composite additive is 1:0.7) to obtain the mixture; S3. The mixture is first heated to 750℃ at 12℃ / min and calcined for 300min. The calcination capacity is 35t / h and the oxygen flow rate during calcination is 30L / min. The mixture is then cooled down in the furnace and ball-milled to obtain a 200-mesh fine powder. S4. Add a 25% sulfuric acid solution at 70℃ to the mixed fine powder for two-stage leaching. The pH value of the first leaching is 4, and the leaching time is 45 minutes. The pH value of the second leaching is 1.5, and the leaching time is 4 minutes. A vanadium-containing solution with a volume concentration of 30 g / L is obtained. Add a 25% sulfuric acid solution and ammonium sulfate to the vanadium-containing solution to adjust the pH value to 2. Vanadium is precipitated at 80℃ for 95 minutes (the mass ratio of vanadium-containing solution to ammonium sulfate is 100:3.0). Ammonium metavanadate and wastewater are obtained. S5. Add FeSO4 to the wastewater (the amount of FeSO4 added is 12 kg / m³). 3 After reducing for 20 minutes, lime is added until the pH of the wastewater reaches 9, resulting in purified water, gypsum, and Mn(OH)2. The purified water is returned to the leaching or vanadium precipitation process in step S4, and the gypsum and Mn(OH)2 are used to form a composite additive. S6. Ammonium metavanadate was dried at 120℃ for 7 hours, then heated to 500℃ at a rate of 10℃ / min and calcined for 3 hours. Finally, it was melted at 850℃ for 8 minutes to obtain V₂O₅. A physical image of V₂O₅ is shown below. Figure 1 As shown; the process flow diagram for vanadium extraction from vanadium slag, as follows. Figure 2 As shown.

[0046] Example 4 The only difference between this embodiment and Example 3 is that the mass ratio of Mn(OH)2 to calcium sulfate in gypsum powder is 0.2:1.

[0047] Example 5 The only difference between this embodiment and Example 3 is that the mass ratio of Mn(OH)2 to calcium sulfate in gypsum powder is 0.15:1.

[0048] Example 6 The only difference between this embodiment and Example 3 is that the mass ratio of Mn(OH)2 to calcium sulfate in gypsum powder is 0.1:1.

[0049] Example 7 The only difference between this embodiment and embodiment 4 is that in step S2, the mass ratio of vanadium to composite additive in the refined vanadium slag powder is 1:0.5.

[0050] Example 8 The only difference between this embodiment and embodiment 4 is that in step S2, the mass ratio of vanadium to composite additive in the refined vanadium slag powder is 1:0.3.

[0051] Example 9 The only difference between this embodiment and embodiment 4 is that in step S2, the mass ratio of vanadium in the refined vanadium slag powder to the mass ratio of the composite additive is 1:0.2.

[0052] Example 10 The difference between this embodiment and embodiment 7 is only in step S3, where the calcination is staged. The mixture is first heated to 250°C at 12°C / min and calcined for 120 min; then heated to 550°C at 12°C / min and calcined for 200 min; finally heated to 700°C at 12°C / min and calcined for 120 min. The calcination throughput is 35 t / h, and the oxygen flow rate during calcination is 30 L / min. The mixture is cooled down in the furnace and ball-milled to obtain a 200-mesh fine powder.

[0053] Example 11 The difference between this embodiment and embodiment 7 is only in step S3, where the calcination is staged. The mixture is first heated to 250°C at 12°C / min and calcined for 60 min; then heated to 550°C at 12°C / min and calcined for 120 min; finally heated to 700°C at 12°C / min and calcined for 60 min. The calcination throughput is 35 t / h, and the oxygen flow rate during calcination is 30 L / min. The mixture is then cooled in the furnace and ball-milled to obtain a 200-mesh fine powder.

[0054] Example 12 The difference between this embodiment and embodiment 7 is only in step S3, where the calcination is staged. The mixture is first heated to 250°C at 12°C / min and calcined for 90 min; then heated to 550°C at 12°C / min and calcined for 150 min; finally heated to 700°C at 12°C / min and calcined for 100 min. The calcination throughput is 35 t / h, and the oxygen flow rate during calcination is 30 L / min. The mixture is cooled down in the furnace and ball-milled to obtain a 200-mesh fine powder.

[0055] Example 13 The difference between this embodiment and embodiment 7 is only in step S3, where the calcination is segmented. The mixture is first heated to 300°C at 12°C / min and calcined for 90 min; then heated to 610°C at 12°C / min and calcined for 150 min; finally heated to 760°C at 12°C / min and calcined for 100 min. The calcination throughput is 35 t / h, and the oxygen flow rate during calcination is 30 L / min. The mixture is then cooled in the furnace and ball-milled to obtain a 200-mesh fine powder.

[0056] Example 14 The difference between this embodiment and embodiment 7 is only in step S3, where the calcination is segmented. The mixture is first heated to 600°C at 12°C / min and calcined for 90 min; then heated to 750°C at 12°C / min and calcined for 150 min; finally heated to 1000°C at 12°C / min and calcined for 100 min. The calcination throughput is 35 t / h, and the oxygen flow rate during calcination is 30 L / min. The mixture is then cooled in the furnace and ball-milled to obtain a 200-mesh fine powder.

[0057] Example 15 The difference between this embodiment and embodiment 7 is only in step S3, where the calcination is staged. The mixture is first heated to 650°C at 12°C / min and calcined for 90 min; then heated to 800°C at 12°C / min and calcined for 150 min; finally heated to 1100°C at 12°C / min and calcined for 150 min. The calcination throughput is 35 t / h, and the oxygen flow rate during calcination is 30 L / min. The mixture is then cooled in the furnace and ball-milled to obtain a 200-mesh fine powder.

[0058] Comparative Example 1 The only difference between this comparative example and Example 3 is a composite additive for vanadium slag roasting, which includes the following components: Mn(OH)2.

[0059] Comparative Example 2 The only difference between this comparative example and Example 3 is a composite additive for vanadium slag roasting, which includes the following components: gypsum powder.

[0060] Comparative Example 3 The only difference between this comparative example and Example 3 is a composite additive for vanadium slag roasting, which includes the following components: gypsum powder and Mg(OH)2. The mass ratio of calcium sulfate in Mg(OH)2 and gypsum powder is 0.25:1.

[0061] Comparative Example 4 The only difference between this comparative example and Example 3 is a composite additive for vanadium slag roasting, which includes the following components: gypsum powder and manganese carbonate. The mass ratio of manganese carbonate to calcium sulfate in gypsum powder is 0.25:1.

[0062] The V2O5 prepared in Examples 1-15 and Comparative Examples 1-4 were tested according to the following method: Vanadium recovery rate from vanadium slag = (molar amount of vanadium pentoxide obtained / molar amount of vanadium slag (based on vanadium element)) × 100%; The test results are shown in Table 1: Table 1 Vanadium recovery results of Examples 1-15 and Comparative Examples 1-4

[0063] The dosage of adjuvants consumed in Examples 1-3 was statistically analyzed; The statistical results are shown in Table 2: Table 2 Consumption of Composite Additives in Examples 1-3

[0064] 1. Compared with Comparative Examples 1 to 4, the vanadium recovery rate of Examples 1 to 15 is much higher than that of Comparative Examples 1 to 4. The vanadium recovery rate of Examples 1 to 15 is above 95%, indicating that the use of the composite additive of Mn(OH)2 and gypsum powder can significantly improve the vanadium recovery rate. In addition, the consumption of gypsum and Mn(OH)2 in Examples 1 to 3 is low, which greatly reduces the production cost.

[0065] 2. Compared with Examples 3 to 6, the vanadium recovery rate of Examples 4 to 5 is higher than that of Examples 3 and 6, indicating that further limiting the mass ratio of Mn(OH)2 to calcium sulfate in gypsum powder to 0.15 to 0.2:1 can further improve the vanadium recovery rate.

[0066] 3. Compared with Examples 4 and 7-9, the vanadium recovery rate of Examples 7-8 is higher than that of Examples 4 and 9, indicating that adjusting the mass ratio of vanadium to composite additive in refined vanadium slag powder to 1:0.3-0.5 helps to improve the vanadium recovery rate.

[0067] 4. Compared with Examples 7 and Examples 10-15, the vanadium recovery rate of Examples 13-14 is higher than that of Examples 7, Examples 10-12 and Examples 15, indicating that selecting three-stage roasting and controlling the temperature range during roasting can improve the vanadium recovery rate.

[0068] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A composite additive for vanadium slag roasting, characterized in that, It includes the following components: gypsum powder and Mn(OH)2; The mass ratio of Mn(OH)2 to calcium sulfate in gypsum powder is 0.1~0.3:

1.

2. The composite additive for vanadium slag roasting according to claim 1, characterized in that, The method for preparing the gypsum powder includes the following steps: drying and crushing gypsum to obtain gypsum powder; The gypsum powder has a particle size of 50-200 mesh; The mass ratio of Mn(OH)2 to calcium sulfate in gypsum powder is 0.15~0.2:

1.

3. The application of a composite additive for vanadium slag roasting as described in any one of claims 1 to 2 in vanadium slag extraction, characterized in that, The vanadium extraction from the vanadium slag includes the following steps: S1. The vanadium slag is crushed and ball-milled to produce vanadium slag powder; the vanadium slag powder is then magnetically separated to obtain refined vanadium slag powder and iron concentrate. S2. Mix the refined vanadium slag powder and the composite additive to obtain a mixture; S3. The mixture is calcined and ball-milled to obtain a fine powder. S4. The mixed fine powder is added to an acid solution for leaching to obtain a vanadium-containing solution; vanadium is precipitated from the vanadium-containing solution to obtain ammonium metavanadate and wastewater; S5. The wastewater is neutralized to obtain purified water, gypsum and Mn(OH)2; the purified water is reused in the leaching or vanadium precipitation in step S4, and the gypsum and Mn(OH)2 are recovered as components of the composite additive. S6. The ammonium metavanadate is dried, calcined, and melted to produce V2O5.

4. The application according to claim 3, characterized in that, The particle size of the vanadium slag powder is 50~200 mesh; The particle size of the mixed fine powder is 100~500 mesh.

5. The application according to claim 3, characterized in that, The mass ratio of vanadium in the refined vanadium slag powder to the mass ratio of the composite additive is 1:0.3~0.

5.

6. The application according to claim 3, characterized in that, The calcination temperature is 300~1000℃, the time is 240~440min, and the oxygen flow rate is 10~50L / min.

7. The application according to claim 3, characterized in that, The roasting includes a first stage roasting, a second stage roasting, and a third stage roasting; The first stage of roasting involves heating to 300-600℃ at a rate of 10-15℃ / min for 60-120min. The second stage of roasting involves raising the temperature to 610-750℃ at a rate of 10-15℃ / min for 120-200min. The third stage of roasting involves heating the temperature at 10-15℃ / min to 760-1000℃ for 60-120 minutes.

8. The application according to claim 3, characterized in that, The acid solution includes a dilute sulfuric acid solution; The mass concentration of the dilute sulfuric acid solution is 10%~50%, and the temperature is 50~90℃; The volume concentration of the vanadium-containing solution is 2~30 g / L; The vanadium precipitation process includes the following steps: adding sulfuric acid solution and ammonium sulfate solution to the vanadium-containing solution to adjust the pH to 1-3, and initiating a precipitation reaction; The precipitation reaction is carried out at a temperature of 80~100℃ for a time of 45~95 min; The mass ratio of the vanadium-containing solution to ammonium sulfate is 100:1.0~5.

0.

9. The application according to claim 3, characterized in that, The leaching includes primary leaching and secondary leaching; The pH value of the primary leaching is 3-5; The primary leaching time is 40-55 minutes; The pH value of the secondary leaching is 1~2; The secondary leaching time is 2-6 minutes.

10. The application according to claim 3, characterized in that, In step S5, the neutralization process includes the following steps: adding FeSO4 to the wastewater, initiating a reduction reaction, and then adding lime to adjust the pH of the wastewater to 8-11; The amount of FeSO4 added is 1~20 kg / m³. 3 .

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