Method for cleaning and extracting vanadium from vanadium slag and application thereof

Abstract

The application provides a vanadium slag cleaning vanadium extraction method and application thereof. The method comprises the following steps: mixing vanadium slag and sodium salt, sintering, adding roasting clinker, water, chromium removal mother liquor and impurity removal slag, leaching to obtain tailings and leaching liquor, removing impurities from the leaching liquor to obtain purified liquor, performing precipitation treatment on the purified liquor to obtain vanadium precipitation mother liquor and calcium vanadate; adding a first reducing agent to the vanadium precipitation mother liquor to obtain chromium hydroxide, calcining to obtain chromium sesquioxide; performing vanadium leaching on the calcium vanadate, carbon dioxide, crystallization mother liquor and calcination tail gas to obtain calcium salt and sodium vanadate solution, evaporating and crystallizing the sodium vanadate solution to obtain sodium metavanadate, performing high-temperature reduction on the sodium metavanadate, an auxiliary agent and a second reducing agent to obtain reduced clinker, and performing sodium removal on the reduced clinker, sodium bicarbonate mother liquor and water to obtain vanadium sesquioxide. The application successfully prepares chromium sesquioxide and vanadium sesquioxide products, and realizes high-value utilization of high-chromium vanadium slag.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of metallurgical chemical industry, and particularly relates to a method for clean extraction of vanadium from vanadium slag and application thereof. BACKGROUND

[0002] Vanadium is an important rare metal element, and its main products include vanadium pentoxide, vanadium trioxide, vanadium-nitrogen alloy, vanadium-iron alloy, vanadium-aluminum alloy, etc. Due to its anti-fatigue effect, excellent hardness and strength, vanadium is widely used in aviation, chemical industry, metallurgy and steel industry. At present, vanadium extraction from vanadium slag accounts for 80% of the total industry, of which 90% is sodium extraction technology. The key to preparing vanadium oxide from vanadium slag is the separation of vanadium and sodium. The traditional method is to separate vanadium and sodium based on the difference between sodium and ammonium and vanadate, and then prepare vanadium oxide, but this method is also the root cause of the serious pollution of three wastes in the current vanadium industry.

[0003] CN109930008A discloses a method for clean extraction of vanadium from vanadium slag. The method mixes vanadium slag and magnesium compound for roasting, roasts the calcine with sulfuric acid for acid leaching, and uses ammonium salt for vanadium precipitation, and then roasts to obtain vanadium pentoxide; ammonia water is introduced into the vanadium precipitation liquid to precipitate manganese hydroxide and magnesium hydroxide, and the magnesium hydroxide is calcined into magnesium oxide and returned to the vanadium slag roasting. This method uses magnesium salt instead of sodium salt, avoiding the generation of sodium sulfate wastewater, but more ammonia-nitrogen-containing wastewater and ammonia-containing tail gas are generated.

[0004] CN106544515A discloses a method for extracting vanadium from vanadium slag, which comprises the following steps: under the condition of first heating and stirring, spraying an aqueous solution of an alkali metal-containing alkali substance into vanadium slag to obtain a mixture, and then sequentially performing second heating and stirring and water leaching on the mixture to extract vanadium. The temperature of the first heating and stirring is 80-120℃, and the temperature of the second heating and stirring is 500-750℃. However, this method only obtains vanadium leaching solution, and the subsequent vanadium product still needs to be obtained by traditional process, and the mixing process of vanadium slag and alkali solution has very high requirements on equipment.

[0005] CN112080651A discloses a method for extracting vanadium by ammonium composite roasting of high-calcium and low-sodium vanadium slag. The method mixes vanadium slag, limestone, sodium-containing compound and ammonium salt in a certain proportion, roasts, leaches, washes and filters to obtain vanadium leaching solution and residue, and then obtains vanadium pentoxide by ammonium salt precipitation and calcination. Although this method improves the recovery rate of vanadium, the ammonium salt will decompose to produce ammonia gas during roasting, which increases a new pollution source, and the vanadium precipitation wastewater contains a large amount of ammonia-nitrogen and sulfur, which is very serious pollution to the environment.

[0006] CN114854988A discloses a method for selectively separating vanadium and chromium from vanadium-chromium material by using CO2, which selectively oxidizes vanadium in vanadium-chromium raw materials to achieve vanadium-chromium separation. The specific steps are as follows: mixing vanadium-chromium material and carbonate, briquetting, and putting into a shaft furnace to pass in carbon dioxide for roasting. After cooling, crushing and dissolving, a vanadium-containing solution and a chromium-containing residue are obtained. Vanadium is recovered from the vanadium-containing solution by precipitation method, and the chromium-containing residue is used to prepare chromium alloy. Vanadium is oxidized at the same time, and part of chromium is also oxidized, which will enter the product and wastewater, not only reducing the product quality, but also increasing the difficulty of wastewater treatment. This method also has high ammonia nitrogen and high sulfur wastewater and ammonia-containing tail gas.

[0007] Therefore, it is urgent for technical personnel in the field to develop a new method for extracting vanadium from vanadium slag without sulfur and ammonium, and to reduce the emission of three wastes. SUMMARY

[0008] The purpose of the present application is to provide a method for clean extraction of vanadium from vanadium slag and its application.

[0009] To achieve the purpose of the present application, the following technical solutions are adopted:

[0010] One of the purposes of the present application is to provide a method for clean extraction of vanadium from vanadium slag, which comprises the following steps:

[0011] (1) mixing vanadium slag and sodium salt, sintering, adding roasting clinker, water, chromium removal mother liquor and impurity removal residue, leaching to obtain tailings and leaching solution, removing impurities from the leaching solution to obtain purified solution, and precipitating the purified solution to obtain vanadium precipitation mother liquor and calcium vanadate;

[0012] (2) adding a first reducing agent to the vanadium precipitation mother liquor of step (1) to obtain chromium hydroxide, and calcining to obtain chromium sesquioxide;

[0013] (3) leaching vanadium from calcium vanadate, carbon dioxide, crystallization mother liquor and calcined tail gas of step (1) to obtain calcium salt and sodium vanadate solution, evaporating and crystallizing the sodium vanadate solution to obtain sodium metavanadate, reducing the sodium metavanadate, an auxiliary agent and a second reducing agent at high temperature to obtain a reduced clinker, and de-sodiuming the reduced clinker, sodium bicarbonate mother liquor and water to obtain vanadium sesquioxide.

[0014] The method provided by the application realizes the separation of vanadium and sodium according to the solubility difference between vanadium and chromium and sodium salt and calcium salt, and successfully prepares the products of chromium sesquioxide and vanadium sesquioxide by introducing a reducing agent and an auxiliary agent, and realizes the high-value utilization of high-chromium vanadium slag. Compared with the traditional method, the application eliminates the introduction of sulfur and ammonium, avoids the generation of high-salt and high-ammonia-nitrogen wastewater from the source, and realizes the zero discharge of wastewater and solid waste through the closed circulation of sodium salt and a transformation agent. In addition, the entire system does not produce ammonia-containing waste gas. The entire process is simple to operate, has high conversion rate and low cost, the required equipment is conventional equipment in the chemical field, the industrial process is easy to realize, and the economic and environmental benefits are significant.

[0015] As a preferred technical solution of the application, the sodium salt in step (1) is sodium carbonate and / or sodium bicarbonate.

[0016] Preferably, the sintering temperature in step (1) is 700-1100 DEG C, wherein the temperature can be 700 DEG C, 750 DEG C, 800 DEG C, 850 DEG C, 900 DEG C, 950 DEG C, 1000 DEG C, 1050 DEG C or 1100 DEG C, etc., but not only limited to the listed values, other values not listed in this range are also applicable.

[0017] Preferably, the molar ratio of total sodium to total vanadium in the reaction system in the sintering in step (1) is (1-1.4):1, wherein the molar ratio can be 1:1, 1.1:1, 1.2:1, 1.3:1 or 1.4:1, etc., but not only limited to the listed values, other values not listed in this range are also applicable.

[0018] Preferably, the mass ratio of water to calcined clinker in step (1) is (1-3):1, wherein the mass ratio can be 1:1, 2:1 or 3:1, etc., but not only limited to the listed values, other values not listed in this range are also applicable.

[0019] As a preferred technical solution of the application, the impurity removal in step (1) includes adding calcium oxide to the leaching solution to remove impurities, to obtain an impurity removal residue and a purified liquid.

[0020] Preferably, in the impurity removal, the calcium oxide:(P+Si) is (2-4):1, wherein the calcium oxide:(P+Si) can be 2:1, 3:1 or 4:1, etc., but not only limited to the listed values, other values not listed in this range are also applicable.

[0021] Preferably, the impurity removal residue is recycled to step (1).

[0022] As a preferred technical solution of the application, the precipitation treatment in step (1) includes adding calcium oxide to the purified liquid to precipitate vanadium, to obtain a vanadium precipitation mother liquor and calcium vanadate.

[0023] Preferably, the molar ratio of total calcium to total vanadate in the reaction system during the precipitation treatment of step (1) is controlled to be (1-1.4):1, wherein the molar ratio can be 1:1, 1.1:1, 1.2:1, 1.3:1, or 1.4:1, etc., but is not limited to the listed values, and other values not listed within the range of the values are also applicable.

[0024] As a preferred technical solution of the present application, carbon dioxide is introduced into the vanadium precipitation mother liquor of step (2) to recover sodium bicarbonate, and the sodium bicarbonate mother liquor is obtained. A reducing agent is added to the sodium bicarbonate mother liquor to obtain chromium oxide and a chromium removal mother liquor.

[0025] Preferably, the pH of the solution is 7.0-9.0 during the recovery of sodium bicarbonate, wherein the pH can be 7.0, 7.2, 7.4, 7.6, 7.8, 8.0, 8.2, 8.4, 8.6, 8.8, or 9.0, etc., but is not limited to the listed values, and other values not listed within the range of the values are also applicable.

[0026] Preferably, the first reducing agent includes any one or a combination of at least two of formic acid, oxalic acid, formaldehyde, hydrazine hydrate, methanol, or ethanol, wherein typical but non-limiting examples of the combination include a combination of formic acid and oxalic acid, a combination of oxalic acid and formaldehyde, a combination of formaldehyde and hydrazine hydrate, a combination of hydrazine hydrate and methanol, or a combination of methanol and ethanol, etc.

[0027] Preferably, the chromium removal mother liquor is recycled to step (1).

[0028] Preferably, the temperature of the calcination of step (2) is 900-1600°C, wherein the temperature can be 900°C, 1000°C, 1100°C, 1200°C, 1300°C, 1400°C, 1500°C, or 1600°C, etc., but is not limited to the listed values, and other values not listed within the range of the values are also applicable.

[0029] As a preferred technical solution of the present application, the pH of the solution is controlled to be 9.0-10.0 during the leaching of step (3), wherein the pH can be 9.0, 9.2, 9.4, 9.6, 9.8, or 10.0, etc., but is not limited to the listed values, and other values not listed within the range of the values are also applicable.

[0030] Preferably, the calcium salt after calcination of step (3) is returned to step (1) as a decontaminating agent.

[0031] As a preferred technical solution of the present application, the sodium vanadate solution in step (3) is evaporated and crystallized to obtain sodium metavanadate, condensed water, and a crystallization mother liquor.

[0032] Preferably, the auxiliary agent in step (3) comprises any one or a combination of at least two of aluminum oxide, aluminum hydroxide or aluminum phosphate, wherein the typical but non-limiting examples of the combination are: a combination of aluminum oxide and aluminum hydroxide, a combination of aluminum hydroxide and aluminum phosphate, a combination of aluminum oxide and aluminum phosphate, etc.

[0033] Preferably, the second reducing agent in step (3) comprises any one or a combination of at least two of hydrogen, CO, coal gas or natural gas, wherein the typical but non-limiting examples of the combination are: a combination of hydrogen and CO, a combination of CO and coal gas, a combination of coal gas and natural gas, a combination of hydrogen and natural gas, etc.

[0034] Preferably, the temperature of the high-temperature reduction in step (3) is 600-900℃, wherein the temperature can be 600℃, 650℃, 700℃, 750℃, 800℃, 850℃ or 900℃, etc., but not only limited to the listed values, other values not listed in the range of the values are also applicable.

[0035] Preferably, the molar ratio of total aluminum to total sodium in the high-temperature reduction in step (3) is controlled to be (1-1.4):1, wherein the molar ratio can be 1:1, 1.1:1, 1.2:1, 1.3:1 or 1.4:1, etc., but not only limited to the listed values, other values not listed in the range of the values are also applicable.

[0036] As a preferred technical solution of the present application, the reduction clinker, sodium bicarbonate mother liquor and water in step (3) are subjected to sodium removal to obtain vanadium trioxide and a sodium-removed solution.

[0037] Preferably, in the sodium removal process, the mass ratio of water to reduction clinker is controlled to be (2-5):1, wherein the mass ratio can be 2:1, 3:1, 4:1 or 5:1, etc., but not only limited to the listed values, other values not listed in the range of the values are also applicable.

[0038] Preferably, carbon dioxide is introduced into the sodium-removed solution, and the pH is controlled to be 10.0-12.0, wherein the pH can be 10.0, 10.2, 10.4, 10.6, 10.8, 11.0, 11.2, 11.4, 11.6, 11.8 or 12.0, but not only limited to the listed values, other values not listed in the range of the values are also applicable, to obtain an auxiliary agent and an auxiliary agent mother liquor.

[0039] Preferably, carbon dioxide is continuously introduced into the auxiliary agent, and the pH is controlled to be 7.0-9.0, wherein the pH can be 7.0, 7.2, 7.4, 7.6, 7.8, 8.0, 8.2, 8.4, 8.6, 8.8 or 9.0, etc., but not only limited to the listed values, other values not listed in the range of the values are also applicable, to obtain sodium bicarbonate and a sodium bicarbonate mother liquor.

[0040] Preferably, the sodium bicarbonate returns to step (1) as a decontaminant.

[0041] Preferably, the sodium bicarbonate mother liquor returns to step (3) to participate in sodium removal.

[0042] As a preferred technical solution of the present application, the method comprises the following steps:

[0043] (1) After mixing vanadium slag and sodium salt, sintering is carried out at 700-1100℃, after adding calcined clinker, water, de-chromium mother liquor and decontamination residue, leaching is carried out, the molar ratio of total sodium and total vanadium in the reaction system is controlled to be (1-1.4):1, tailings and leaching solution are obtained, the leaching solution is decontaminated to obtain a purified solution, and the purified solution is subjected to precipitation treatment to obtain a vanadium precipitation mother liquor and calcium vanadate, and the molar ratio of total calcium and total vanadate in the reaction system in the precipitation treatment is controlled to be (1-1.4):1;

[0044] (2) A first reducing agent is added to the vanadium precipitation mother liquor of step (1) to obtain chromium hydroxide, and after calcination, chromium sesquioxide is obtained;

[0045] (3) Vanadium leaching is carried out on the calcium vanadate, carbon dioxide, crystallization mother liquor and calcined tail gas of step (1) to obtain calcium salt and sodium vanadate solution, and sodium metavanadate is obtained by evaporation and crystallization of the sodium vanadate solution, a reducing clinker is obtained by high-temperature reduction of the sodium metavanadate, auxiliary agent and second reducing agent at a temperature of 600-900℃, and vanadium trioxide is obtained by sodium removal of the reducing clinker, sodium bicarbonate mother liquor and water.

[0046] The second object of the present application is to provide an application of the vanadium slag cleaning and vanadium extraction method according to the first object, which is applied to the field of metallurgical chemical engineering.

[0047] Compared with the prior art, the present application has the following beneficial effects:

[0048] (1) The method provided by the present application directly converts high-chromium vanadium slag into high-value chromium sesquioxide and vanadium trioxide products. The present application does not need to introduce sulfur and ammonium, thereby avoiding the generation of high-salt and high-ammonia-nitrogen wastewater from the source, and achieving zero discharge of wastewater and solid waste through the closed cycle of sodium salt and transformation agent. In addition, the entire system does not produce ammonia-containing waste gas. The entire process is simple to operate, has high conversion rate and low cost, the required equipment is conventional equipment in the chemical field, the industrial process is easy to implement, and the economic and environmental benefits are significant.

[0049] (2) The method provided by the present application has high product purity, the purity of the chromium sesquioxide product meets the requirements of the I-class qualified product in HG / T2775-2010, and the purity of the vanadium trioxide product meets the requirements of the V2O366 grade in GB / T40301-2021. BRIEF DESCRIPTION OF DRAWINGS

[0050] Figure 1 is a flow chart of the vanadium slag cleaning and vanadium extraction method of embodiments 1-10 of the present application. DETAILED DESCRIPTION

[0051] The technical solutions of the present application will be further illustrated by specific embodiments. Those skilled in the art should understand that the embodiments are only to help understand the present application and should not be regarded as specific limitations of the present application.

[0052] Embodiment 1

[0053] The present embodiment provides a method for cleaning and extracting vanadium from vanadium slag as shown in the flow chart, which comprises the following steps: Figure 1 The method for cleaning and extracting vanadium from vanadium slag as shown in the flow chart, which comprises the following steps:

[0054] (1) Roasting vanadium slag and sodium salt at 1000℃, controlling the molar ratio of total sodium to total vanadium in the reaction system to be 1.1:1, mixing the roasted clinker, water, chromium removal mother liquor, vanadium precipitation mother liquor and impurity removal residue to perform vanadium-chromium leaching, controlling the mass ratio of water to roasted clinker to be 2:1, to obtain tailings and leaching solution; adding calcium oxide to the leaching solution to remove impurities, controlling the mass ratio of calcium oxide:(P+Si) to be 3:1, to obtain impurity removal residue and purified solution, the impurity removal residue returns to step (1), and adding calcium oxide to the purified solution to precipitate vanadium, controlling the molar ratio of total calcium to total vanadate in the reaction system to be 1.2:1, to obtain vanadium precipitation mother liquor and calcium vanadate;

[0055] (2) Passing carbon dioxide into the vanadium precipitation mother liquor, controlling the solution PH to be 8, recovering sodium bicarbonate and returning it to step (1), and adding formic acid to the sodium bicarbonate mother liquor to reduce all high-valence chromium in the solution to trivalent chromium, to obtain chromium hydroxide and chromium removal mother liquor, the chromium removal mother liquor returns to step (1), and the chromium hydroxide is calcined to obtain chromium sesquioxide;

[0056] (3) Mixing calcium vanadate, carbon dioxide, crystallization mother liquor and calcined tail gas to perform vanadium leaching, controlling the solution PH to be 9-10 (or all calcium is precipitated in the form of a precipitate), to obtain calcium salt and sodium vanadate solution, the calcium salt is calcined and returned to step (1); the sodium vanadate solution is evaporated and crystallized to obtain sodium metavanadate, condensed water and crystallization mother liquor, the sodium metavanadate, aluminum oxide and hydrogen gas are mixed and reduced at 750℃ to obtain reduced clinker, controlling the molar ratio of total aluminum to total sodium in the reaction system to be 1.1:1; mixing the reduced clinker, sodium bicarbonate mother liquor and water to remove sodium, controlling the mass ratio of water to reduced clinker to be 3:1, to obtain vanadium sesquioxide and sodium removal solution; passing carbon dioxide into the sodium removal solution, controlling the solution PH to be 11, to obtain an additive and additive mother liquor, continuing to pass carbon dioxide into the additive mother liquor, controlling the solution PH to be 8, to obtain sodium bicarbonate and sodium bicarbonate mother liquor, the sodium bicarbonate returns to step (1), and the sodium bicarbonate mother liquor returns to be recycled.

[0057] Example 2

[0058] The present embodiment provides a method for clean vanadium extraction from vanadium slag as shown in the flow chart, comprising the following steps: Figure 1 The method for clean vanadium extraction from vanadium slag as shown in the flow chart, comprising the following steps:

[0059] (1) Roasting vanadium slag and sodium salt at 1100℃, controlling the molar ratio of total sodium to total vanadium in the reaction system to be 1.2:1, mixing the roasted clinker, water, chromium removal mother liquor, vanadium precipitation mother liquor and impurity removal residue to perform vanadium-chromium leaching, controlling the mass ratio of water to roasted clinker to be 3:1, to obtain tailings and leaching solution; adding calcium oxide to the leaching solution for impurity removal, controlling the mass ratio of calcium oxide:(P+Si) to be 4:1, to obtain impurity removal residue and purified solution, and returning the impurity removal residue to step (1); adding calcium oxide to the purified solution to precipitate vanadium, controlling the molar ratio of total calcium to total vanadate in the reaction system to be 1.1:1, to obtain vanadium precipitation mother liquor and calcium vanadate;

[0060] (2) Passing carbon dioxide into the vanadium precipitation mother liquor, controlling the solution PH to be 7.5, recovering sodium bicarbonate and returning it to step (1); adding oxalic acid to the sodium bicarbonate mother liquor to reduce all high-valence chromium in the solution to trivalent chromium, to obtain chromium hydroxide and chromium removal mother liquor, and returning the chromium removal mother liquor to step (1); and calcining the chromium hydroxide to obtain chromium sesquioxide;

[0061] (3) Mixing calcium vanadate, carbon dioxide, crystallization mother liquor and calcined tail gas to perform vanadium leaching, controlling the solution PH to be 9-10 (or all calcium is precipitated in the form of a precipitate), to obtain calcium salt and sodium vanadate solution, and returning the calcium salt to step (1) after calcination; evaporating and crystallizing the sodium vanadate solution to obtain sodium metavanadate, condensed water and crystallization mother liquor; mixing the sodium metavanadate, aluminum hydroxide and CO, and reducing at 900℃ to obtain reduction clinker, controlling the molar ratio of total aluminum to total sodium in the reaction system to be 1.2:1; mixing the reduction clinker, sodium bicarbonate mother liquor and water to remove sodium, controlling the mass ratio of water to reduction clinker to be 2:1, to obtain vanadium sesquioxide and sodium removal solution; passing carbon dioxide into the sodium removal solution, controlling the solution PH to be 10, to obtain an additive and additive mother liquor, continuing to pass carbon dioxide into the additive mother liquor, controlling the solution PH to be 7, to obtain sodium bicarbonate and sodium bicarbonate mother liquor, and returning the sodium bicarbonate to step (1) and returning the sodium bicarbonate mother liquor to recycling.

[0062] Example 3

[0063] The present embodiment provides a method for clean vanadium extraction from vanadium slag as shown in the flow chart, comprising the following steps: Figure 1 The method for clean vanadium extraction from vanadium slag as shown in the flow chart, comprising the following steps:

[0064] (1) Vanadium slag and sodium salt are calcined at 800℃, the molar ratio of total sodium to total vanadium in the reaction system is controlled to be 1:1, the mixed calcined clinker, water, chromium removal mother liquor, vanadium precipitation mother liquor and impurity removal residue are used for vanadium and chromium leaching, the mass ratio of water to calcined clinker is 2:1, tailings and leaching solution are obtained; calcium oxide is added to the leaching solution for impurity removal, the mass ratio of calcium oxide to (P+Si) is controlled to be 2:1, impurity removal residue and purified solution are obtained, the impurity removal residue returns to step (1), calcium oxide is added to the purified solution to precipitate vanadium, the molar ratio of total calcium to total vanadium in the reaction system is controlled to be 1:1, vanadium precipitation mother liquor and calcium vanadate are obtained;

[0065] (2) Carbon dioxide is introduced into the vanadium precipitation mother liquor, the solution PH is controlled to be 8.5, sodium bicarbonate is recovered and returned to step (1), formaldehyde is added to the sodium bicarbonate mother liquor to reduce all high-valence chromium to trivalent chromium, chromium hydroxide and chromium removal mother liquor are obtained, the chromium removal mother liquor returns to step (1), and chromium hydroxide is calcined to obtain chromium sesquioxide;

[0066] (3) Calcium vanadate, carbon dioxide, crystallization mother liquor and calcined tail gas are mixed to leach vanadium, the solution PH is controlled to be 9-10 (or all calcium is precipitated in the form of a precipitate), calcium salt and sodium vanadate solution are obtained, the calcium salt is calcined and returned to step (1); sodium vanadate solution is evaporated and crystallized to obtain sodium metavanadate, condensed water and crystallization mother liquor, sodium metavanadate, aluminum phosphate and coal gas are mixed and reduced at 600℃ to obtain a reduction clinker, the molar ratio of total aluminum to total sodium in the reaction system is controlled to be 1:1; the reduction clinker, sodium bicarbonate mother liquor and water are mixed for sodium removal, the mass ratio of water to reduction clinker is controlled to be 4:1, vanadium sesquioxide and sodium removal solution are obtained; carbon dioxide is introduced into the sodium removal solution, the solution PH is controlled to be 12, an additive and an additive mother liquor are obtained, carbon dioxide is continuously introduced into the additive mother liquor, the solution PH is controlled to be 8.5, sodium bicarbonate and sodium bicarbonate mother liquor are obtained, the sodium bicarbonate returns to step (1), and the sodium bicarbonate mother liquor returns to recycling.

[0067] Example 4

[0068] In this example, the mass ratio of water to calcined clinker in step (1) is replaced by 1:1, and the remaining steps are the same as those in Example 1.

[0069] Example 5

[0070] In this example, the molar ratio of total calcium to total vanadate in the reaction system in step (1) is replaced by 1.4:1, and the remaining steps are the same as those in Example 1.

[0071] Example 6

[0072] In this example, the molar ratio of total aluminum to total sodium in the reaction system in step (3) is replaced by 1.4:1, and the other conditions are the same as those in Example 1.

[0073] Example 7

[0074] The example is identical to example 1 except that the mass ratio of water to reduced raw material in step (3) is replaced by 5:1.

[0075] Example 8

[0076] The example is identical to example 1 except that the molar ratio of total calcium to total vanadate in the reaction system in step (1) is replaced by 0.8:1.

[0077] Example 9

[0078] The example is identical to example 1 except that the molar ratio of total aluminum to total sodium in the reaction system in step (3) is replaced by 0.7:1.

[0079] Example 10

[0080] The example is identical to example 1 except that the mass ratio of water to reduced raw material in step (3) is replaced by 1:1.

[0081] The purity of the chromium trioxide and vanadium trioxide prepared in examples 1-10 is tested, and the test results are shown in Table 1.

[0082] Table 1

[0083]

[0084]

[0085] The purity of the chromium trioxide in examples 1-7 of the present application all meet the requirements of the I-class qualified product in HG / T 2775-2010, and the purity of the vanadium trioxide all meet the requirements of the grade V2O366 in GB / T 40301-2021. Among them, compared with example 1, since there is too much calcium oxide in step (1) of example 5, a large amount of calcium oxide remains and enters the calcium vanadate in the form of solid phase, although it is discharged in the form of calcium salt during vanadium leaching, which does not affect the purity of the product, but affects the energy consumption and the utilization rate of calcium, that is, it adversely affects the economy. Compared with example 1, the amount of water added in step (3) of example 7 is too high, although it does not affect the purity of the vanadium trioxide, but it affects the recovery rate of sodium, that is, it adversely affects the economy.

[0086] The content of chromium trioxide in Example 8 is 90.4%, which does not meet the requirements of the I-class qualified product in HG / T 2775-2010; the vanadium content of the obtained vanadium trioxide product is 66.3%, which meets the requirements of the V2O366 grade in GB / T 40301-2021. The content of chromium trioxide in Example 9 is 98.3%, which meets the requirements of the I-class qualified product in HG / T 2775-2010; the vanadium content of the obtained vanadium trioxide product is 62.1%, which does not meet the requirements of the V2O366 grade in GB / T 40301-2021. The content of chromium trioxide in Example 10 is 98.7%, which meets the requirements of the I-class qualified product in HG / T 2775-2010; the vanadium content of the obtained vanadium trioxide product is 60.5%, which does not meet the requirements of the V2O366 grade in GB / T 40301-2021. Compared with Example 1, since the water addition amount in Example 10 is insufficient, the impurities in the reduced clinker cannot be completely washed off, and part of them enter the vanadium trioxide product, thereby reducing the product quality.

[0087] Without being limited thereto, it should be understood that any variation or modification of the present application, which would be obvious to those skilled in the art, is within the scope and spirit of the present application.

Claims

1. A method for cleaning and extracting vanadium from vanadium slag, characterized in that, The method includes the following steps: (1) After sintering the vanadium slag and sodium salt, add the roasted clinker, water, chromium removal mother liquor and impurity removal slag and leach to obtain tailings and leachate. Remove impurities from the leachate to obtain purified liquid. Perform precipitation treatment on the purified liquid to obtain vanadium precipitate mother liquor and calcium vanadate. (2) Add the first reducing agent to the vanadium precipitation mother liquor in step (1) to obtain chromium hydroxide, and calcine it to obtain chromium trioxide; The first reducing agent includes any one or a combination of at least two of formic acid, oxalic acid, formaldehyde, hydrazine hydrate, methanol, or ethanol; (3) Leach vanadium from the calcium vanadate, carbon dioxide, crystallization mother liquor and calcination tail gas in step (1) to obtain calcium salt and sodium vanadate solution. Evaporate and crystallize the sodium vanadate solution to obtain sodium metavanadate. Reduce the sodium metavanadate, the additive and the second reducing agent at high temperature to obtain reduced clinker. Remove sodium from the reduced clinker, sodium bicarbonate mother liquor and water to obtain vanadium trioxide.

2. The method according to claim 1, characterized in that, The sodium salt in step (1) is sodium carbonate and / or sodium bicarbonate.

3. The method according to claim 1, characterized in that, The sintering temperature in step (1) is 700~1100℃.

4. The method according to claim 1, characterized in that, In step (1), the molar ratio of total sodium to total vanadium in the sintering reaction system is controlled to be (1~1.4):

1.

5. The method according to claim 1, characterized in that, The mass ratio of water to roasted clinker in step (1) is (1~3):

1.

6. The method according to claim 1, characterized in that, The impurity removal in step (1) includes: adding calcium oxide to the leachate to remove impurities, thereby obtaining impurity-removed residue and purified liquid.

7. The method according to claim 1, characterized in that, In the impurity removal process, the mass ratio is controlled as calcium oxide:(P+Si)=(2~4):

1.

8. The method according to claim 1, characterized in that, The impurities removed are returned to step (1) for recycling.

9. The method according to claim 1, characterized in that, The precipitation treatment in step (1) includes: adding calcium oxide to the purified liquid to precipitate vanadium, thereby obtaining vanadium precipitate mother liquor and calcium vanadate.

10. The method according to claim 9, characterized in that, In step (1), the molar ratio of total calcium to total vanadate in the precipitation treatment is controlled to be (1~1.4):

1.

11. The method according to claim 1, characterized in that, Carbon dioxide is introduced into the vanadium precipitation mother liquor in step (2) to recover sodium bicarbonate, resulting in sodium bicarbonate mother liquor. A first reducing agent is added to the sodium bicarbonate mother liquor to obtain chromium hydroxide and chromium removal mother liquor.

12. The method according to claim 11, characterized in that, During the recovery of sodium bicarbonate, the pH of the solution is 7.0 to 9.

0.

13. The method according to claim 1, characterized in that, The chromium removal mother liquor is returned to step (1) for recycling.

14. The method according to claim 1, characterized in that, The calcination temperature in step (2) is 900~1600℃.

15. The method according to claim 1, characterized in that, During leaching in step (3), the pH of the solution is controlled to be 9.0~10.

0.

16. The method according to claim 1, characterized in that, The calcium salt described in step (3) is calcined and then returned to step (1) as a purification agent.

17. The method according to claim 1, characterized in that, In step (3), sodium vanadate solution is evaporated and crystallized to obtain sodium metavanadate, condensate and mother liquor.

18. The method according to claim 1, characterized in that, The additives in step (3) include any one or a combination of at least two of alumina, aluminum hydroxide, or aluminum phosphate.

19. The method according to claim 1, characterized in that, Step (3) The second reducing agent includes any one or a combination of at least two of hydrogen, CO, coal gas or natural gas.

20. The method according to claim 1, characterized in that, The high-temperature reduction in step (3) is at a temperature of 600~900℃.

21. The method according to claim 18, characterized in that, In step (3), the molar ratio of total aluminum to total sodium is controlled to be (1~1.4):1 during the high-temperature reduction.

22. The method according to claim 1, characterized in that, The reduced clinker, sodium bicarbonate mother liquor and water described in step (3) are desodiumed to obtain vanadium trioxide and desodium-removed solution.

23. The method according to claim 1, characterized in that, During the sodium removal process, the mass ratio of water to reduced clinker is controlled to be (2~5):

1.

24. The method according to claim 22, characterized in that, Carbon dioxide is bubbled into the desodium solution to control the pH at 10.0-12.0, thereby obtaining the auxiliary agent and the auxiliary agent mother liquor.

25. The method according to claim 24, characterized in that, Carbon dioxide is continuously introduced into the mother liquor of the auxiliary agent to control the pH at 7.0~9.0, thereby obtaining sodium bicarbonate and sodium bicarbonate mother liquor.

26. The method according to claim 25, characterized in that, The sodium bicarbonate is returned to step (1) as a purification agent.

27. The method according to claim 25, characterized in that, The sodium bicarbonate mother liquor is returned to step (3) to participate in sodium removal.

28. The method according to claim 1, characterized in that, The method includes the following steps: (1) After mixing vanadium slag and sodium salt, sinter at 700~1100℃, add roasted clinker, water, chromium removal mother liquor and impurity removal slag and leach, control the molar ratio of total sodium and total vanadium in the reaction system to be (1~1.4):1, and obtain tailings and leachate. Remove impurities from the leachate to obtain purified liquid. Perform precipitation treatment on the purified liquid to obtain vanadium precipitation mother liquor and calcium vanadate. During the precipitation treatment, control the molar ratio of total calcium and total vanadate in the reaction system to be (1~1.4):

1. (2) Add the first reducing agent to the vanadium precipitation mother liquor in step (1) to obtain chromium hydroxide, and calcine it to obtain chromium trioxide; (3) Leach vanadium from the calcium vanadate, carbon dioxide, crystallization mother liquor and calcination tail gas in step (1) to obtain calcium salt and sodium vanadate solution. Evaporate and crystallize the sodium vanadate solution to obtain sodium metavanadate. Reduce the sodium metavanadate, the additive and the second reducing agent at a high temperature of 600~900℃ to obtain reduced clinker. Remove sodium from the reduced clinker, sodium bicarbonate mother liquor and water to obtain vanadium trioxide.

29. The application of a method for clean vanadium extraction from vanadium slag as described in any one of claims 1-28, characterized in that, The method is applied in the field of metallurgical and chemical technology.

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