Method for preparing ammonium metavanadate from vanadium slag sodium treatment lixivium

Abstract

The invention belongs to the technical field of wet-process vanadium extraction, and particularly relates to a method for preparing ammonium metavanadate from vanadium slag sodium salt leachate, which comprises the following steps: S1, after vanadium slag sodium salt roasting, leaching and impurity removal are performed to obtain vanadium-containing leachate; s2, a chromium removal agent and a silicon removal agent are added into the vanadium-containing leachate, and after chromium and silicon are removed, solid-liquid separation is conducted to obtain a first solution; s3, adding an oxidizing agent into the first solution for oxidation to obtain a second solution; and S4, carrying out ammonium salt vanadium precipitation on the second solution to obtain ammonium metavanadate, and further preparing the ammonium metavanadate into a vanadium product. The method has the advantages of short flow, less auxiliary material consumption, less energy power, less required equipment and facilities, high vanadium yield and low production cost, and is beneficial to promoting the application of vanadium products in the non-steel field.

Description

Technical Field

[0001] The invention belongs to the technical field of wet vanadium extraction, and particularly relates to a method for preparing ammonium metavanadate by sodiumizing vanadium slag leaching solution. Background Art

[0002] In order to further improve the quality of vanadium oxide products, Panzhihua Iron and Steel has achieved a technological breakthrough. Its process includes: vanadium slag is sodium-treated and roasted, and then leached and impurities are removed to obtain a clear and transparent vanadium-containing leachate. The pH value of the vanadium-containing leachate is 9.5-11.0, and the solution temperature is 60-65°C. A certain amount of special chromium removal agent (such as Na 2 S), after constant temperature stirring for 1h, sulfuric acid is added to adjust the solution pH to about 8.5, ≤65℃, and a certain amount of aluminum sulfate is added to remove silicon from the solution. After stirring for 1h, it is put into a buffer tank and allowed to settle for 24h. After the supernatant and underflow are filtered through plate and frame and filter press, the solution enters the liquid storage tank for standby use, and the filter cake is disposed of separately. The solution after chromium and silicon removal is precipitated with vanadium in the normal acidic ammonium salt to obtain APV (ammonium polyvanadate). After washing and drying, APV enters the rotary kiln to react with coal gas to obtain high-quality vanadium trioxide.

[0003] At present, Panzhihua Iron and Steel uses aluminum sulfate to desiliconize the vanadium-containing leachate after sodium vanadium slag extraction, and directly uses ammonium sulfate to precipitate ammonium metavanadate. It is found that after solid-liquid separation and washing, the content of impurities Si, P, Pb, Fe, Mo, W, Cl, As, Ca, Mg, K, Na, and Al in the obtained ammonium metavanadate can meet the requirements of the first-grade product in YS / T 1022-2015, but the S≥0.02% and Cr≥0.04% of the ammonium metavanadate cannot meet the quality indicators of the second-grade product in YS / T 1022-2015. The production process of precipitating APV, re-dissolving APV, then precipitating SAV (sodium ammonium vanadate), re-dissolving, and then precipitating AMV (ammonium metavanadate), and drying to obtain ammonium metavanadate, after strengthening AMV washing and centrifugation, the quality of the obtained ammonium metavanadate can meet the quality indicators of the first-grade product in YS / T 1022-2015, but the production process is long and the cost is high, which is not conducive to production.

[0004] Prior art CN202310615044 discloses a method for preparing battery-grade vanadium pentoxide, and CN202210945743 discloses a method for refining vanadium pentoxide from vanadium liquid, but the above process flow is long and the production cost is high. Prior art CN202311331431 discloses a method for preparing ammonium metavanadate with a density higher than 1.0g / cm3, but the quality of the ammonium metavanadate obtained by this method does not meet the secondary product index of YS / T 1022-2015.

[0005] In summary, there is an urgent need to develop a method for preparing ammonium metavanadate with a short process, less consumption of auxiliary materials and energy, less equipment and facilities, high vanadium yield and low production cost. Summary of the invention

[0006] In view of this, the purpose of the present invention is to utilize the chromium removal technology for preparing high-quality vanadium trioxide, directly remove chromium and silicon from the vanadium-containing leaching solution, filter the solution, add an oxidant to the filtrate, oxidize the trivalent chromium in the solution into hexavalent chromium, cool the solution, add ammonium bicarbonate to precipitate vanadium, and obtain ammonium metavanadate, which is then centrifuged, washed, and dried to obtain ammonium metavanadate, meeting the first-class quality index of YS / T 1022-2015. The present invention is aimed at vanadium slag sodiumization vanadium extraction liquid, has a short process, consumes less auxiliary materials, energy and power, requires less equipment and facilities, has a high vanadium yield, and has a low production cost. The technical scheme of the present invention is as follows: The present invention provides a method for preparing ammonium metavanadate from sodium vanadium slag leaching solution, comprising the following steps: S1. After sodium vanadium slag is roasted, leaching and impurity removal are performed to obtain a vanadium-containing leaching solution; S2. Adding a chromium removal agent and a silicon removal agent to the vanadium-containing leachate, removing chromium and silicon, and obtaining a first solution by solid-liquid separation; S3. Adding an oxidizing agent to the first solution to obtain a second solution; S4. The second solution is subjected to ammonium salt precipitation of vanadium to obtain ammonium metavanadate, which is further prepared into vanadium products.

[0007] In some embodiments, S2 further comprises adding lignocellulosic slurry for further purification after chromium and silicon removal to obtain a first solution.

[0008] In some embodiments, the purification conditions include: under stirring and heating conditions, the system temperature is ≥60°C, and the system constant temperature time is ≥45min.

[0009] In some embodiments, the pH of the S2 system is ≤7.

[0010] In some embodiments, the oxidant in S3 comprises: H 2 O 2 NH 4 ) 2 S 2 O 8 Or Na 2 S 2 O 8 One or more of .

[0011] In some embodiments, the oxidation in S3 is oxidation under stirring conditions, and the oxidation time is 0.5~2h.

[0012] In some embodiments, S3 further comprises cooling the second solution to a temperature ≤ 20°C.

[0013] In some embodiments, S4 further includes cooling the system during the ammonium salt vanadium precipitation process on the second solution to ensure that the vanadium precipitation temperature is 10-20°C.

[0014] In some embodiments, in S4, the temperature of the vanadium precipitation solution is 12-17° C., the ammonium addition coefficient of the ammonium salt is 1.5-2.5, and the solution is stirred at a constant temperature for 2-3 hours.

[0015] In some embodiments, the ammonium salt includes one or more of ammonium sulfate, aqueous ammonia, ammonium chloride, ammonium bicarbonate, or ammonium carbonate.

[0016] The beneficial effects of the present invention include at least: The present invention directly removes chromium and silicon from the vanadium-containing leaching solution, and then adds a special chromium removal agent to remove Cr 6+ Reduction to Cr 3+ Cr is expressed as Cr(OH) 3 The precipitate is removed, and then the solution is filtered, and an oxidant is added to the filtrate to oxidize the residual trivalent chromium in the solution into hexavalent chromium, so that Cr exists in the second solution in a water-soluble form, and then ammonium is added to precipitate vanadium, so that Cr exists in the supernatant in a water-soluble form. In the present invention, an oxidant is added after chromium removal, and Cr is removed more thoroughly. The obtained ammonium metavanadate is further prepared into vanadium products, and the vanadium products meet the first-class quality indicators of YS / T 1022-2015. The present invention has a short process, consumes less auxiliary materials and energy, requires less equipment and facilities, has a high vanadium yield, and has a low production cost, which is conducive to promoting the application of vanadium products in non-steel fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention. For ordinary technicians in this field, other embodiments can be obtained based on these drawings without paying creative work.

[0018] Figure 1 A flow chart of a method for preparing ammonium metavanadate from sodium vanadium slag leaching solution provided in some embodiments of the present invention; Figure 2 Shown is a schematic diagram of an apparatus for preparing metavanadic acid in some embodiments of the present invention.

[0019] Description of Reference Numerals 1. Vanadium liquid pipe after chromium and silicon removal; 2. Wood cellulose slurry pipe; 3. First agitator; 4. First degassing pipe; 5. First liquid level gauge; 6. First pH meter; 7. Heating loop pipe; 8. De-impurity tank; 9. First pump; 10. Filter; 11. Second liquid level gauge; 12. Second agitator; 13. Second degassing pipe; 14. First feeding port; 15. Oxidation tank; 16. Second pump; 17. Cooler; 18. First thermometer; 19. Third degassing pipe; 20. Third liquid level gauge; 21. Liquid storage tank; 22. Third pump; 23. Fourth degassing pipe; 24. Fourth liquid level gauge; 25. Third agitator; 26. Second feeding port; 27. Flow tube; 28. The second pH meter; 29. ​​The second thermometer; 30. The cooling jacket; 31. The vanadium precipitation tank; 32. The underflow pipe; 33. The first opening; 34. The second opening; 35. The third opening; 36. The fourth opening; 37. The main degassing pipeline. DETAILED DESCRIPTION

[0020] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the embodiments of the present invention are further described in detail below in combination with specific embodiments and with reference to the accompanying drawings.

[0021] It should be noted that all expressions using "first" and "second" in the embodiments of the present invention are for distinguishing two non-identical entities with the same name or non-identical parameters. It can be seen that "first" and "second" are only for the convenience of expression and should not be understood as limitations on the embodiments of the present invention. The subsequent embodiments will not explain this one by one.

[0022] In the present invention, the term "ammonium addition coefficient" refers to the ratio of the amount of ammonium salt to TV, where TV is the total vanadium content.

[0023] like Figure 1 As shown, the present invention provides a method for preparing ammonium metavanadate from sodium vanadium slag leaching solution, comprising the following steps: S1. After sodium vanadium slag is roasted, leaching and impurity removal are performed to obtain a vanadium-containing leaching solution; S2. Adding a chromium removal agent and a silicon removal agent to the vanadium-containing leachate, removing chromium and silicon, and obtaining a first solution by solid-liquid separation; S3. Adding an oxidizing agent to the first solution to obtain a second solution; S4. The second solution is subjected to ammonium salt precipitation of vanadium to obtain ammonium metavanadate, which is further prepared into vanadium products.

[0024] In the present invention, the special chromium removal agent is added to remove Cr 6+ Reduction to Cr 3+ Therefore, a large amount of Cr is in the form of Cr(OH) 3 The precipitate is removed, but a small amount of Cr(OH) remains 3Therefore, after filtering out most of the fine suspended matter, an oxidant is used to remove the remaining Cr 3+ Oxidized to Cr 6+ , so that Cr exists in the vanadium solution in a water-soluble form. After vanadium precipitation with ammonium salt, Cr exists in the supernatant in a water-soluble form, and Cr removal is more thorough; at the same time, the oxidant also oxidizes the chromium removal agent or intermediate product remaining in the vanadium solution, destroying the reducing atmosphere of the original system, which is more conducive to impurity removal. Thus, Cr and S in ammonium metavanadate meet the standards of the non-ferrous metal industry.

[0025] The invention utilizes the chromium removal technology for preparing high-quality vanadium trioxide. After the vanadium-containing leaching solution is directly chromium and silicon removed, the solution is firstly filtered, an oxidant is added to the filtrate, trivalent chromium in the solution is oxidized into hexavalent chromium, the solution is cooled, and ammonium bicarbonate is added to precipitate vanadium to obtain ammonium metavanadate, which is then centrifuged, washed and dried to obtain ammonium metavanadate, and the vanadium products meet the first-class product quality index of YS / T 1022-2015.

[0026] In some embodiments, the chromium removal agent is Na 2 S. Na 2 S is a strong reducing agent. In some embodiments of the present invention, the chromium removal agent is not limited to Na 2 S, other 6+ Reduction to Cr 3+ The Cr in the vanadium-containing leaching solution is converted into Cr(OH) 3 Strong reducing agents whose precipitates are removed are within the scope of the present invention.

[0027] In some embodiments, the silicon removal agent includes but is not limited to any of the following: calcium carbonate (CaCO 3 ), magnesium chloride (MgCl 2 ), calcium chloride (CaCl 2 ), polyaluminium ferric chloride (PAFC) or lime (CaO).

[0028] In some embodiments, the vanadium product is vanadium trioxide.

[0029] In some embodiments, S2 further comprises adding lignocellulosic slurry for further purification after chromium and silicon removal to obtain a first solution.

[0030] Cr(OH) generated in the process of chromium and silicon removal 3 、Al(OH) 3Although the suspended solids have settled, a small amount of them still remain in the solution; the cellulose is boiled for a long time to swell and prepare into cellulose slurry, and the cellulose slurry is added. The swollen cellulose continuously absorbs the surrounding suspended solids in the solution, thereby achieving the purpose of purifying the vanadium solution after removing chromium and silicon; at the same time, the cellulose has good filterability and can further remove Cr(OH) 3 、Al(OH) 3 And other suspended matter.

[0031] In some embodiments, the purification conditions include: under stirring and heating conditions, the system temperature is ≥60°C, and the system constant temperature time is ≥45min. The purpose of selecting the above purification conditions in the present invention is to make the lignocellulosic slurry more stable and to better purify the suspended matter in the system.

[0032] In some embodiments, the pH of the S2 system is ≤7. That is, it is an alkaline vanadium-containing leaching solution, the purpose of which is to provide an alkaline environment so that the chromium removal agent can remove Cr 6+ Reduction to Cr 3+ strong reducing agent, so that the Cr in the vanadium-containing leaching solution is converted into Cr(OH) 3 The sediment is removed.

[0033] In some embodiments, the oxidant in S3 comprises: H 2 O 2 NH 4 ) 2 S 2 O 8 Or Na 2 S 2 O 8 In the present invention, an oxidant is added to convert V in the first solution into 4+ Cr 3+ Oxidized to V 5+ Cr 6+ , thereby increasing the V yield and reducing the Cr content in the finished product to meet the product specifications. In some embodiments, the oxidant is selected from (NH 4 ) 2 S 2 O 8 , added (NH 4 ) 2 S 2 O 8 After the reaction, the NH 4 + It can be used in the next step of vanadium precipitation.

[0034] In some embodiments, the oxidation in S3 is oxidation under stirring conditions, and the oxidation time is 0.5 to 2 hours. The oxidation time of the present invention is further 0.8 to 1.2 hours. In some embodiments, the oxidation time is 1 hour. 4+ Cr 3+ Oxidized to V 5+ Cr 6+ .

[0035] In some embodiments, S3 further comprises cooling the second solution to a temperature ≤ 20° C. The purpose of cooling the second solution in the present invention is to facilitate further cooling of the system during the ammonium salt vanadium precipitation process.

[0036] In some embodiments, S4 further includes cooling the system during the ammonium salt vanadium precipitation process on the second solution to ensure that the vanadium precipitation temperature is 10-20°C.

[0037] In some embodiments, in S4, the temperature of the vanadium precipitation solution is 12-17°C, the ammonium addition coefficient of the ammonium salt is 1.5-2.5, and the solution is stirred at a constant temperature for 2-3 hours. In some embodiments, the vanadium precipitation temperature is 13-16°C. Specifically, the temperature of ammonium metavanadate precipitation is controlled at about 15°C, because the lower the temperature, the higher the vanadium yield of ammonium metavanadate, but the lower the temperature, the finer the particles of ammonium metavanadate generated, and the finer the material, the higher the viscosity of the material, and the more difficult it is to wash and remove impurities. Taking both into consideration, the optimal vanadium precipitation temperature is about 15°C.

[0038] If the temperature is low, the vanadium yield is high. The ammonium metavanadate generated at low temperature has fine particles and the material is sticky, which increases the difficulty of washing. Considering the above two points, the best vanadium precipitation temperature is about 15°C.

[0039] In some embodiments, the ammonium salt includes one or more of ammonium sulfate, ammonia water, ammonium chloride, ammonium bicarbonate or ammonium carbonate. In some specific embodiments, compared with the quality index of the product ammonium metavanadate, due to the index requirements of the two elements S and Cl (≤0.01%), ammonium sulfate and ammonium chloride are not suitable for producing the product; combined with the process control difficulty and quality stability of precipitating ammonium metavanadate with ammonia water, ammonium bicarbonate or ammonium carbonate, the ammonium salt is selected as ammonium bicarbonate.

[0040] In some specific embodiments, the technical solution of the present invention is further described in combination with the devices in the prior art: Example 1 The present invention also provides a device for preparing ammonium metavanadate, such as Figure 2As shown, it includes a de-impurity tank 8, a filter 10, an oxidation tank 15, a cooler 17, a liquid storage tank 21 and a vanadium precipitation tank 31 connected in sequence through pipelines. The vanadium-containing leaching solution passes through the de-impurity tank 8, the filter 10, the oxidation tank 15, the cooler 17, the liquid storage tank 21 and the vanadium precipitation tank 31 in sequence to finally obtain ammonium metavanadate. The upper end of the impurity removal tank 8 is respectively connected with a chromium and silicon removal rear vanadium night tube 1, a lignocellulose slurry tube 2, a first agitator 3, a first steam removal tube 4 and a first liquid level meter 5, the middle of the impurity removal tank 8 is connected with a first pH meter 6 and a heating loop tube 7, and the bottom of the impurity removal tank 8 is connected with a first pump 9, the first pump 9 is connected to one side of a filter 10 through a pipeline, and then the other side of the filter 10 is connected to the upper part of an oxidation tank 15 through a pipeline; The upper part of the oxidation tank 15 is also connected to a second liquid level gauge 11, a second agitator 12, a second degassing pipe 13, and a first feed port 14. The bottom of the oxidation tank 15 is connected to a second pump 16. The second pump 16 is connected to one end of a cooler 17 through a pipeline, and the other end of the cooler 17 is connected to the upper end of a liquid storage tank 21 through a pipeline. A first thermometer 18 is provided on the pipeline between the cooler 17 and the liquid storage tank 21, a third degassing pipe 19 and a third liquid level gauge 20 are connected to the upper end of the liquid storage tank 21, and a third pump 22 is connected to the bottom end of the liquid storage tank 21; the third pump 22 is connected to the upper part of the vanadium precipitation tank 31 through a pipeline; The upper part of the vanadium precipitation tank 31 is also connected to the fourth degassing pipe 23, the fourth liquid level meter 24, the third agitator 25, the second feeding port 26, and the middle part of the vanadium precipitation tank 31 is also connected to the flow tube 27, the second pH meter 28, and the second thermometer 29. The bottom of the vanadium precipitation tank 31 is connected to the bottom of the underflow pipe 32. The outer side of the vanadium precipitation tank 31 is sleeved with a cooling jacket 30. The bottom end of the cooling jacket 30 is provided with a first opening 33 adapted to add coolant. The upper part of the cooling jacket 30 is provided with a second opening 34 connected to the cooling unit. The coolant enters the cooling jacket 30 through the first opening 33 and then returns to the cooling unit through the second opening 34. The first degassing pipe 4, the second degassing pipe 13, the third degassing pipe 19, and the fourth degassing pipe 23 of the device are all connected to the degassing tower through the degassing main pipeline 37; A third opening 35 for coolant to enter is provided at one end of the cooler 17 , and a fourth opening 36 connected to the cooling unit is provided at the other end. The coolant enters the cooler 17 through the third opening 35 and returns to the cooling unit through the fourth opening 36 .

[0041] Open the valve on the first degassing pipe 4 and the valve on the vanadium liquid pipe 1 after chromium and silicon removal, and transfer the vanadium-containing leaching solution to the impurity removal tank 8. Observe the first liquid level meter 5. When the vanadium-containing leaching solution in the impurity removal tank 8 reaches a certain liquid level, close the valve on the vanadium liquid pipe 1 after chromium and silicon removal, start the first agitator 3, open the valve on the wood cellulose slurry pipe 2, and transfer the prepared wood cellulose slurry to the impurity removal tank 8 in a certain amount. The heating loop 7 is turned on, and the heating loop 7 heats up the system in the impurity removal tank 8 to a temperature ≥60°C, and after the constant temperature time is ≥45min, the stirring and heating are stopped, and the first pump 9 is started to pump the solution in the impurity removal tank 8 to the filter 10 (which can be a plate frame, bag type, etc.) for solid-liquid separation, and then the first solution is obtained, and the first solution enters the oxidation tank 15, and the valve on the second degassing pipe 13 is opened; the filter cake (or filter mud) obtained from the filter 10 is used for other purposes, the first liquid level meter 5 detects the liquid level in the impurity removal tank 8, and the first pH meter 6 detects the pH value of the solution in the impurity removal tank 8.

[0042] When the liquid level in the oxidation tank 15 reaches the specified level (measured by the second liquid level meter 11), the first pump 9 is stopped, the second agitator 12 is started, and the oxidant is added to the oxidation tank 15 through the first feed port 14. After the first solution and the oxidant react for 1 hour, the second solution is obtained, the second agitator 12 is stopped, the second pump 16 is started, and the second solution in the oxidation tank 15 is transported to the cooler 17 for cooling. The temperature of the cooled second solution is preferably ≤20°C. The cooled second solution is transported to the liquid storage tank 21 for standby use.

[0043] The outer wall of the vanadium precipitation tank 31 is sleeved with a cooling jacket 30, and a coolant is introduced into the cooling jacket 30 through the first opening 33 to cool the solution in the vanadium precipitation tank 31. The valve on the fourth degassing pipe 23 is opened, and the third pump 22 is started to transport the second solution in the liquid storage tank 21 to the vanadium precipitation tank 31. When the liquid level in the vanadium precipitation tank 31 reaches a certain value, the third agitator 25 is started and the coolant is introduced into the cooling jacket 30 to cool the solution in the tank. After the system is cooled to a temperature of about 15°C, the feed port valve is opened to add a certain amount of ammonium salt to the vanadium precipitation tank 31 to precipitate vanadium with ammonium salt to produce ammonium metavanadate. The solution temperature in the vanadium precipitation tank 31 is kept at a constant temperature of 15°C, and the ammonium addition coefficient is 1.5~2.5, preferably 2.0, and the constant temperature stirring is 2~3h, generally 3h. After the vanadium precipitation time is over, the third agitator 25 is stopped, and the slurry in the vanadium precipitation tank 31 is left to stand for 1 hour, and then the valve on the side flow pipe is opened to discharge the supernatant in the vanadium precipitation tank 31. After the supernatant is discharged, the valve on the bottom flow pipe 32 of the vanadium precipitation tank 31 is opened to discharge the ammonium metavanadate slurry in the tank, and further prepare it into vanadium products. The preparation process includes solid-liquid separation of the ammonium metavanadate slurry and washing the ammonium metavanadate with deionized water. After washing, the ammonium metavanadate enters the microwave dryer for drying, and the drying temperature is 70~85℃. The water content of the dried ammonium metavanadate is ≤0.1% and the color is white.

[0044] In some specific embodiments of the present invention, according to the aforementioned device, the impurity removal tank 8 has the same size as the oxidation tank 15, with a cylinder diameter of 3m and a height of 4.3m, an elliptical arc bottom (height 0.5m), a rotation speed of the agitator in the tank of 62r / min, and an empty height of ≥0.5m in the case of stirring. The filter 10 is a bag type, containing 16 filter bags with a diameter of 200mm and a length of 1600mm, and the filter cloth pore size is 10um. The liquid storage tank 21 has a diameter of 5m and a height of 22m. The cylinder diameter of the vanadium precipitation tank 31 is 3.5m and a height of 5m, and the bottom is an elliptical arc bottom (height 0.5m). The rotation speed of the first agitator 3 in the tank is 62r / min, and the empty height of the tank is ≥0.5m in the case of stirring. The side flow pipe of the vanadium precipitation tank 31 is 1.0m away from the lower edge of the cylinder.

[0045] The chemical composition of the vanadium-containing leaching solution is shown in Table 1.

[0046]

[0047] According to the production process of the present invention, 25m³ of vanadium-containing leaching solution (components are shown in Table 1) is added to the impurity removal tank 8, 5kg of lignocellulose slurry (on a dry basis) is added to the tank, heated to 70°C, and stirred at a constant temperature for 1 hour. After passing through the filter 10 (bag type), a first solution is obtained, and some chemical components of the first solution are shown in Table 2.

[0048]

[0049] As can be seen from Table 2, using wood cellulose to absorb fine suspended matter and filter it can effectively remove some impurities.

[0050] After the impurities are removed, 25 kg of (NH 4 ) 2 S 2 O 8 , after stirring for 1 hour, it is pumped to the cooler 17 to cool to 15°C and then discharged into the liquid storage tank 21 for standby use. The vanadium solution in the liquid storage tank 21 is pumped to the vanadium precipitation tank 31 for vanadium precipitation operation. The vanadium precipitation temperature is 15°C, the ammonium addition coefficient is 2.0, the constant temperature stirring time is 2h, and the sedimentation time is 1h. The concentration of the supernatant V is measured to be 0.37g / L. The obtained ammonium metavanadate is centrifuged and washed, and then dried in a microwave dryer at 75°C. The obtained ammonium metavanadate is white and has a water content of 0.08%. The chemical composition of ammonium metavanadate is shown in Table 3. The product meets the quality indicators of the first-class product in the national non-ferrous metal industry standard YS / T 1022-2015.

[0051]

[0052] in conclusion: The present invention directly removes chromium and silicon from the vanadium-containing leaching solution, and then adds a special chromium removal agent to remove Cr 6+ Reduction to Cr 3+ (like Na 2 S), so a large amount of Cr is in the form of Cr(OH) 3 The precipitate is removed, the solution is filtered, and an oxidant is added to the filtrate to oxidize the trivalent chromium in the solution into hexavalent chromium. At the same time, the oxidant also oxidizes the chromium removal agent (a strong reducing agent is used for the chromium removal agent of the present invention) or the intermediate product remaining in the vanadium solution, destroying the reducing atmosphere of the original system, which is conducive to further chromium removal. After initially removing most of the fine suspended matter, the oxidant is used to remove the remaining Cr 3+ Oxidized to Cr 6+ , allowing Cr to exist in the vanadium solution in a water-soluble form, then adding ammonium bicarbonate to precipitate vanadium, allowing Cr to exist in the supernatant in a water-soluble form, removing Cr more thoroughly, and obtaining ammonium metavanadate, which is then centrifuged, washed, and dried to obtain ammonium metavanadate, meeting the first-class quality index of YS / T 1022-2015. The present invention has a short process, consumes less auxiliary materials, energy and power, requires less equipment and facilities, has a high vanadium yield, and has a low production cost, which is conducive to promoting the application of vanadium products in the non-steel field.

[0053] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0054] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for preparing ammonium metavanadate from sodium vanadium slag leaching solution, It is characterized in that The steps include: S1. After sodium vanadium slag is roasted, leaching and impurity removal are performed to obtain a vanadium-containing leaching solution; S2. Adding a chromium removal agent and a silicon removal agent to the vanadium-containing leachate, removing chromium and silicon, and obtaining a first solution by solid-liquid separation; S3. Adding an oxidizing agent to the first solution to obtain a second solution; S4. The second solution is subjected to ammonium salt precipitation of vanadium to obtain ammonium metavanadate, which is further prepared into vanadium products.

2. The method according to claim 1, It is characterized in that The S2 also includes adding lignocellulose slurry for further purification after chromium and silicon removal to obtain a first solution.

3. The method according to claim 2, It is characterized in that The purification conditions include: under stirring and heating conditions, the system temperature is ≥60°C, and the system constant temperature time is ≥45min.

4. The method according to claim 1, It is characterized in that The pH of the S2 system is ≤7.

5. The method according to claim 1, It is characterized in that The oxidant in S3 includes: H 2 O 2 NH 4 ) 2 S 2 O 8 Or Na 2 S 2 O 8 One or more of .

6. The method according to claim 1, It is characterized in that The oxidation in S3 is carried out under stirring conditions, and the oxidation time is 0.5 to 2 hours.

7. The method according to claim 6, It is characterized in that The step S3 further includes cooling the second solution to a temperature ≤ 20°C.

8. The method according to claim 1, It is characterized in that In the step S4, the system is further cooled during the ammonium salt vanadium precipitation process of the second solution to ensure that the vanadium precipitation temperature is 10-20°C.

9. The method according to claim 1, It is characterized in that In S4, the temperature of the vanadium precipitation solution is 12-17° C., the ammonium addition coefficient of the ammonium salt is 1.5-2.5, and the solution is stirred at a constant temperature for 2-3 hours.

10. The method according to claim 1, It is characterized in that The ammonium salt includes one or more of ammonium sulfate, ammonia water, ammonium chloride, ammonium bicarbonate or ammonium carbonate.

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