Method for extracting vanadium from calcified vanadium extraction tailings through leaching

Abstract

The invention relates to the technical field of vanadium metallurgy, and discloses a method for extracting vanadium from calcified vanadium extraction tailings through leaching, which comprises the following steps: S1, carrying out chute reselection on the calcified vanadium extraction tailings to obtain coarse-fraction chute reselection slag and fine-fraction chute reselection slag; s2, performing mechanical activation on ammonium bicarbonate, mixing the coarse-fraction chute reselection slag with ammonium bicarbonate, adding hot water, performing bubbling and stirring reaction, and performing solid-liquid separation to obtain desulfurized slag; and S3, dilute nitric acid, calcium fluoride and hydrogen peroxide are added into the desulfurization residues, a reaction is conducted at the temperature of 70-75 DEG C, and secondary leaching tailings and a vanadium-containing solution are obtained through solid-liquid separation. According to the method, the reselection technology is adopted, 90% or above of calcium sulfate can be directly removed, vanadium can be directly extracted through leaching by adding simple chemical reagents, complex processes such as drying, roasting and re-leaching are not needed, the production cost can be greatly reduced, environmental pollution is reduced, the vanadium leaching rate is larger than 65%, and ammonium sulfate can be recycled in the process for follow-up vanadium precipitation.

Description

Technical Field

[0001] The invention relates to the technical field of vanadium metallurgy, and in particular to a method for extracting vanadium by leaching calcified vanadium extraction tailings. Background Art

[0002] As an important strategic resource, vanadium has important and extensive uses in metallurgy, chemical industry, national defense, energy and other fields. At present, vanadium extraction mainly adopts two processes: calcination roasting-sulfuric acid leaching-ammonium salt vanadium precipitation and sodium roasting-water leaching-ammonium salt vanadium precipitation. Among them, vanadium slag is subjected to the "calcination roasting-acid leaching" process to produce acid leaching slag. The content of vanadium pentoxide in the vanadium tailings is 1~2%, which exceeds the vanadium content in vanadium-titanium magnetite and is a valuable secondary resource. At present, the process of vanadium extraction from calcined vanadium tailings is usually to produce vanadium tailings with vanadium slag or lime by mixed roasting. However, the water content in calcined vanadium tailings is high, and the mixed roasting method is difficult. In addition, the TV content in the tailings is relatively low, and vanadium extraction is more difficult. It can be seen that there is currently no better process route for secondary vanadium extraction from calcined vanadium tailings in China. It is necessary to select a better process route for the treatment of calcined vanadium tailings to make the calcined vanadium tailings industrialized.

[0003] Therefore, there is a need in the prior art for improving the method for leaching vanadium from calcified vanadium tailings. Summary of the invention

[0004] In view of this, the purpose of the embodiment of the present invention is to provide a method for leaching vanadium from calcified vanadium extraction tailings. The method is simple to operate and can achieve vanadium extraction by leaching without complicated drying, roasting, re-leaching and other processes.

[0005] Based on the above purpose, the embodiment of the present invention provides a method for leaching vanadium from calcified vanadium extraction tailings, comprising the following steps: S1 performs chute gravity separation on the calcified vanadium extraction tailings to obtain coarse-grained chute gravity separation slag and fine-grained chute gravity separation slag; S2 mechanically activates the ammonium bicarbonate, mixes the coarse-grained chute gravity separation slag and the ammonium bicarbonate, adds hot water and performs bubbling, stirs the reaction, and then separates the solid and liquid to obtain the desulfurized slag; S3: Add dilute nitric acid, calcium fluoride and hydrogen peroxide to the desulfurized slag, react at a temperature of 70-75°C, and separate the solid and liquid to obtain secondary leaching tailings and vanadium-containing solution.

[0006] In some embodiments, in S1, the dry slag of the calcified vanadium extraction tailings includes: iron, vanadium, calcium sulfate, silicon, titanium, manganese, aluminum, magnesium, and phosphorus, wherein, by mass percentage, total iron is 20-35%, total vanadium is 1-2%, calcium sulfate is 15-30%, and silicon is 5-10%.

[0007] In some embodiments, in S2, a ball mill is used to grind and activate the ammonium bicarbonate, and the proportion of -160 mesh particle size in the ammonium bicarbonate particles after ball milling is greater than 90%.

[0008] In some embodiments, in S2, the amount of ammonium bicarbonate added is 2-3% of the mass of dry slag in the calcified vanadium extraction tailings, and the reaction time is 30-50 min.

[0009] In some embodiments, in S2, during bubbling, air is continuously introduced into the liquid, and the air flow rate is ≥0.4 L / min.

[0010] In some embodiments, in S2, the temperature of the hot water is 30-40°C.

[0011] In some embodiments, in S3, the concentration of dilute nitric acid is 0.3-0.5 mol / L, and the amount of dilute nitric acid used is 1-2 times the mass of the wet slag of the calcified vanadium extraction tailings.

[0012] In some embodiments, in S3, the amount of calcium fluoride used is 2-3% of the mass of the wet slag of the calcified vanadium extraction tailings.

[0013] In some embodiments, in S3, the amount of hydrogen peroxide used is 5 to 7 times the amount of all-vanadium substances in the calcified vanadium extraction tailings.

[0014] In some embodiments, in S3, the reaction time is 80 to 100 min.

[0015] The present invention has at least the following beneficial technical effects: 1. The present invention adopts gravity separation technology, which can directly remove more than 90% of calcium sulfate and reduce the subsequent tailings treatment volume by more than 30% (wet weight).

[0016] 2. The present invention can directly leach and extract vanadium by adding simple chemical reagents, without complicated drying, roasting, re-leaching and other processes, which can greatly reduce production costs and reduce environmental pollution. The vanadium leaching rate is greater than 65%, and ammonium sulfate can be recovered in the process for subsequent vanadium precipitation.

[0017] 3. The entire leaching and vanadium extraction process is simple, energy-saving, easy to operate, high in leaching efficiency, and easy to promote on a large scale. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] 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.

[0019] Figure 1 This is a schematic diagram of an embodiment of the method for extracting vanadium by leaching calcified vanadium-extracting tailings provided by the present invention. 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] The terms "including" and "having" and any variations thereof in the specification and claims of the present invention and the above-mentioned drawings are intended to cover non-exclusive inclusions; the terms "first", "second", etc. in the specification and claims of the present invention or the above-mentioned drawings are used to distinguish different objects rather than to describe a specific order. "Multiple" means two or more, unless otherwise clearly and specifically defined.

[0022] In addition, reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present invention. The appearance of the phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0023] The existing process generally produces vanadium-extracting tailings by mixing and roasting with vanadium slag or lime. However, the water content in the calcified vanadium-extracting tailings is relatively high, which makes mixed roasting difficult. In addition, the TV content in the tailings is relatively low, making vanadium extraction more difficult. It can be seen that there is currently no better process route for secondary vanadium extraction from calcified vanadium-extracting tailings in China. It is necessary to select a better process route for treating calcified vanadium-extracting tailings in order to realize the industrialization of calcified vanadium-extracting tailings. Therefore, the present invention provides a method for leaching vanadium from calcified vanadium-extracting tailings, such as Figure 1 The present invention provides a method for leaching vanadium from calcified vanadium extraction tailings, comprising: S1 performs chute gravity separation on the calcified vanadium extraction tailings to obtain coarse-grained chute gravity separation slag and fine-grained chute gravity separation slag; S2 mechanically activates the ammonium bicarbonate, mixes the coarse-grained chute gravity separation slag and the ammonium bicarbonate, adds hot water and performs bubbling, stirs the reaction, and then separates the solid and liquid to obtain the desulfurized slag; S3: adding dilute nitric acid, calcium fluoride and hydrogen peroxide to the desulfurized slag, reacting at a temperature of 70-75° C., and performing solid-liquid separation to obtain secondary leaching tailings and a vanadium-containing solution.

[0024] Furthermore, in S1, the total iron content of the calcified vanadium extraction tailings (dry slag) is 20-35%, the total vanadium content is 1-2%, the calcium sulfate content is 15-30%, the silicon content is 5-10%, and there are also certain amounts of titanium, manganese, aluminum, magnesium, phosphorus, etc. In this step, the tailings are divided into coarse and fine particles through a meticulous chute gravity selection process. This step effectively separates the vanadium-rich fine particle part. Using the specific gravity method and particle size screening mechanism, most of the calcium sulfate and other impurities with a particle size of less than 0.01mm in the tailings were successfully removed. The reduction of these impurities directly reduces the content of non-target components in vanadium products, improves the purity and quality of vanadium products, and meets the demand of the high-end market for high-quality vanadium products.

[0025] Furthermore, in S2, a ball mill is used to grind and activate ammonium bicarbonate, and the proportion of -160 mesh particle size in the ammonium bicarbonate particles after ball milling is greater than 90%. The refinement of the ammonium bicarbonate particles increases its specific surface area, that is, the surface area per unit mass of the material increases, which makes the contact area of ​​ammonium bicarbonate wider when reacting with other substances, and the interaction between the reactants is more sufficient, thereby improving the reaction rate and reaction efficiency.

[0026] The amount of ammonium bicarbonate added is 2-3% of the mass of dry slag in the calcified vanadium tailings, and the reaction time is 30-50 minutes. Then, hot water at 30-40°C is added for bubbling. During bubbling, air is continuously introduced into the liquid, and the air flow rate is ≥0.4L / min. Desulfurization slag is obtained by solid-liquid separation, wherein the filtrate is recovered and used to extract ammonium sulfate. In this step, when the solid particles of the coarse-grained chute gravity separation slag and ammonium bicarbonate are reacted, bubbling helps prevent agglomeration and caking between the particles and maintain the fluidity of the material. The bubbling operation can make the reaction more uniform and sufficient.

[0027] Further, in S3, dilute nitric acid, calcium fluoride and hydrogen peroxide are added to the desulfurized slag, wherein the concentration of the dilute nitric acid is 0.3-0.5 mol / L, and the amount of the dilute nitric acid is 1-2 times the mass of the wet slag of the calcified vanadium extraction tailings (liquid-solid ratio 1:1-2:1). The amount of calcium fluoride is 2-3% of the mass of the wet slag of the calcified vanadium extraction tailings. The amount of hydrogen peroxide is 5-7 times the amount of all-vanadium substances in the calcified vanadium extraction tailings, that is, n(H2O2):n(TV)=5-7. In some embodiments, the reaction is carried out at a temperature of 70-75°C for 80-100 minutes, and the solid-liquid separation is performed to obtain the secondary leaching tailings and the vanadium-containing solution.

[0028] The principle of the method of the present invention is that calcium sulfate in the calcified vanadium extraction tailings blocks the migration and leaching channels of vanadium ions in the tailings, affecting the leaching rate of vanadium, so it is considered to remove calcium sulfate in the tailings in advance. The true specific gravity of the vanadium extraction tailings is 3.3-3.6 g / cm 3The true specific gravity of gypsum slag containing calcium sulfate is 2.5-2.8 g / cm 3 . Since more than 90% of the calcium sulfate in the vanadium-extracting tailings is concentrated in the particle size below 0.01mm, most of the calcium sulfate in the tailings can be effectively removed by separating the vanadium-extracting tailings with a particle size below 0.01mm through the specific gravity method and particle size screening mechanism. The remaining calcium sulfate in the tailings can be converted into calcium carbonate by reacting with ammonium bicarbonate. After subsequent acid leaching, the calcium carbonate dissolves into the solution, making it easier for the acid to enter the tailings and react with the vanadium element. The chemical reaction equation is as follows: CaSO4+2NH4HCO3=(NH4)2SO4+CaCO3↓ +H2O+CO2↑ CaCO3+2HNO3=Ca(NO3)2+H2O + CO2↑ The vanadium in the vanadium extraction tailings exists in the form of +3 and +4 valence, which is difficult to be leached directly under acidic conditions. It needs to be oxidized to a high valence before it can be effectively leached. Under acidic conditions, hydrogen peroxide can effectively oxidize low-valent vanadium to pentavalent vanadium. In addition, because the vanadium-containing spinel phase is wrapped by silicates, the acid and oxidant cannot directly contact and react with the vanadium. Under acidic conditions, calcium fluoride is added and reacts with nitric acid to generate HF, which will destroy the silicate phase, thereby releasing the vanadium-containing spinel phase wrapped by silicates. This allows more low-valent vanadium to be released and oxidized to a high valence in contact with hydrogen peroxide, so that the vanadium is leached into the solution.

[0029] V2O3+2H + +H2O2=2 (VO2) + +2H2O VO2+2H + + H2O2 = 2(VO2) + +2H2O CaF2+2H + = 2HF(aq)+Ca 2+ Mg(V,Al)Si3O 10 (OH)2+HF(aq)+H + +H2O2→SiO2+VO 2+ +Mg 2+ +[SiF6] 2- +[AlF5] 2- +Al 3+ +H2O The present invention will be further explained below in conjunction with specific embodiments.

[0030] Example 1 Take 500g vanadium extraction tailings (dry weight, 31.23% TFe, 21.62% CaSO4, 1.52% V) as raw material: (1) The calcified vanadium extraction tailings are directly subjected to chute gravity separation to obtain coarse-grained chute gravity separation slag and fine-grained chute gravity separation slag; (2) Grind 1.5 g of ammonium bicarbonate with a ball mill for activation; then mix the coarse-grained chute gravity separation slag obtained in step 1 with the mechanically activated ammonium bicarbonate, add 1000 mL of hot water at 40°C and bubble, stir and react for 30 minutes, and obtain desulfurized slag after solid-liquid separation; (3) Add 800 mL of 0.3 mol / L nitric acid, 1.5 g of calcium fluoride, and 100 mL of 30% hydrogen peroxide to the desulfurized slag obtained in the previous step, raise the temperature to 75°C, react for 100 min, and then filter to obtain secondary tailings and vanadium-containing leaching solution; (4) Take 250 mL of vanadium-containing leaching solution, add 0.5 g of polyferric sulfate, stir and remove impurities, and filter after 5 minutes to obtain a qualified solution with V = 13.6 g / L and P = 0.12 g / L.

[0031] In this embodiment, the TV content in the secondary tailings after leaching vanadium from the calcified vanadium tailings is 0.52%, and the vanadium leaching rate is 66.7%.

[0032] Example 2 500 g of vanadium extraction tailings (dry weight, 30.65% TFe, 21.79% CaSO4, 1.65% V) was used as raw material: (1) The calcified vanadium extraction tailings are directly subjected to chute gravity separation to obtain coarse-grained chute gravity separation slag and fine-grained chute gravity separation slag; (2) Grind 1.8 g of ammonium bicarbonate with a ball mill for activation; then mix the coarse-grained chute gravity separation slag obtained in step 1 with the mechanically activated ammonium bicarbonate, add 1000 mL of 40°C hot water and bubble, stir and react for 30 minutes, and obtain desulfurized slag after solid-liquid separation; (3) Add 800 mL of 0.35 mol / L nitric acid, 1.6 g of calcium fluoride, and 105 mL of 30% hydrogen peroxide to the desulfurized slag obtained in the previous step, raise the temperature to 75°C, react for 100 min, and then filter to obtain secondary tailings and vanadium-containing leaching solution; (4) Take 250 mL of vanadium-containing leaching solution, add 0.5 g of polyferric sulfate, stir and remove impurities, and filter after 5 minutes to obtain a qualified solution with V = 13.8 g / L and P = 0.11 g / L.

[0033] In this embodiment, the TV content in the secondary tailings after leaching vanadium from the calcified vanadium tailings is 0.57%, and the vanadium leaching rate is 65.5%.

[0034] Example 3 500 g of vanadium extraction tailings (dry weight, 29.75% TFe, 22.52% CaSO4, 1.38% V) is used as raw material: (1) The calcified vanadium extraction tailings are directly subjected to chute gravity separation to obtain coarse-grained chute gravity separation slag and fine-grained chute gravity separation slag; (2) Grind 1.5 g of ammonium bicarbonate with a ball mill for activation; then mix the coarse-grained chute gravity separation slag obtained in step 1 with the mechanically activated ammonium bicarbonate, add 1000 mL of hot water at 40°C and bubble, stir and react for 30 minutes, and obtain desulfurized slag after solid-liquid separation; (3) Add 800 mL of 0.3 mol / L nitric acid, 1.4 g of calcium fluoride, and 95 mL of 30% hydrogen peroxide to the desulfurized slag obtained in the previous step, raise the temperature to 75°C, react for 100 min, and then filter to obtain secondary tailings and vanadium-containing leaching solution; (4) Take 250 mL of vanadium-containing leaching solution, add 0.5 g of polyferric sulfate, stir and remove impurities, filter after 5 minutes, and obtain a qualified solution with V = 12.6 g / L and P = 0.12 g / L.

[0035] In this embodiment, the TV content in the secondary tailings after leaching vanadium from the calcified vanadium tailings is 0.47%, and the vanadium leaching rate is 65.9%.

[0036] Example 4 500 g of vanadium extraction tailings (dry weight, 28.58% TFe, 21.73% CaSO4, 1.52% V) was used as raw material: (1) The calcified vanadium extraction tailings are directly subjected to chute gravity separation to obtain coarse-grained chute gravity separation slag and fine-grained chute gravity separation slag; (2) Grind 1.5 g of ammonium bicarbonate with a ball mill for activation; then mix the coarse-grained chute gravity separation slag obtained in step 1 with the mechanically activated ammonium bicarbonate, add 1000 mL of hot water at 40°C and bubble, stir and react for 30 minutes, and obtain desulfurized slag after solid-liquid separation; (3) Add 800 mL of 0.3 mol / L nitric acid, 1.6 g of calcium fluoride, and 98 mL of 30% hydrogen peroxide to the desulfurized slag obtained in the previous step, raise the temperature to 75°C, react for 100 min, and then filter to obtain secondary tailings and vanadium-containing leaching solution; (4) Take 250 mL of vanadium-containing leaching solution, add 0.5 g of polyferric sulfate, stir and remove impurities, and filter after 5 minutes to obtain a qualified solution with V = 13.3 g / L and P = 0.11 g / L.

[0037] In this embodiment, the TV content in the secondary tailings after leaching vanadium from the calcified vanadium tailings is 0.47%, and the vanadium leaching rate is 65.9%.

[0038] The present invention adopts gravity separation technology, which can directly remove more than 90% of calcium sulfate and reduce the subsequent tailings treatment volume by more than 30% (wet weight). The present invention can directly leach and extract vanadium by adding simple chemical reagents, without complicated drying, roasting, re-leaching and other processes, which can greatly reduce production costs and reduce environmental pollution. The vanadium leaching rate is greater than 65%, and ammonium sulfate can be recovered in the process for subsequent vanadium precipitation. The entire leaching and vanadium extraction process is simple, energy-saving, easy to operate, high in leaching efficiency, and easy to promote on a large scale.

[0039] The above are exemplary embodiments disclosed in the present invention, but it should be noted that various changes and modifications may be made without departing from the scope disclosed in the embodiments of the present invention as defined in the claims. The functions, steps and / or actions of the method claims according to the disclosed embodiments described herein do not need to be performed in any particular order. In addition, although the elements disclosed in the embodiments of the present invention may be described or required in individual form, they may also be understood as multiple unless explicitly limited to the singular.

[0040] It should be understood that, as used herein, the singular forms "a", "an" are intended to include the plural forms as well, unless the context clearly supports an exception. It should also be understood that, as used herein, "and / or" refers to any and all possible combinations including one or more of the associated listed items.

[0041] The serial numbers of the embodiments disclosed in the above embodiments of the present invention are only for description and do not represent the advantages or disadvantages of the embodiments.

[0042] A person skilled in the art should understand that the discussion of any of the above embodiments is only exemplary and is not intended to imply that the scope of the disclosure of the embodiments of the present invention (including the claims) is limited to these examples; under the concept of the embodiments of the present invention, the technical features in the above embodiments or different embodiments can also be combined, and there are many other changes in different aspects of the above embodiments of the present invention, which are not provided in detail for the sake of simplicity. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the embodiments of the present invention should be included in the protection scope of the embodiments of the present invention.

Claims

1. A method for extracting vanadium by leaching calcified vanadium tailings, It is characterized in that include: S1 performs chute gravity separation on the calcified vanadium extraction tailings to obtain coarse-grained chute gravity separation slag and fine-grained chute gravity separation slag; S2 mechanically activates the ammonium bicarbonate, mixes the coarse-grained chute gravity separation slag and the ammonium bicarbonate, adds hot water and performs bubbling, stirs the reaction, and separates the solid and liquid to obtain the desulfurized slag; S3: adding dilute nitric acid, calcium fluoride and hydrogen peroxide to the desulfurized slag, reacting at a temperature of 70-75° C., and performing solid-liquid separation to obtain secondary leaching tailings and a vanadium-containing solution.

2. The method for leaching vanadium from calcified vanadium tailings according to claim 1, It is characterized in that In S1, the dry slag of the calcified vanadium extraction tailings includes: iron, vanadium, calcium sulfate, silicon, titanium, manganese, aluminum, magnesium, and phosphorus, wherein, by mass percentage, total iron is 20-35%, total vanadium is 1-2%, calcium sulfate is 15-30%, and silicon is 5-10%.

3. The method for leaching vanadium from calcified vanadium tailings according to claim 1, It is characterized in that In S2, the ammonium bicarbonate is ground and activated by a ball mill, and after ball milling, the proportion of -160 mesh particle size in the ammonium bicarbonate particles is greater than 90%.

4. The method for leaching vanadium from calcified vanadium tailings according to claim 1, It is characterized in that In S2, the amount of ammonium bicarbonate added is 2-3% of the mass of dry slag in the calcified vanadium extraction tailings, and the reaction time is 30-50 minutes.

5. The method for leaching vanadium from calcified vanadium tailings according to claim 1, It is characterized in that In S2, air is continuously introduced into the liquid during bubbling, and the air flow rate is ≥0.4L / min.

6. The method for extracting vanadium by leaching calcified vanadium tailings according to claim 1, It is characterized in that In S2, the temperature of the hot water is 30~40℃.

7. The method for extracting vanadium by leaching calcified vanadium tailings according to claim 1, It is characterized in that In S3, the concentration of the dilute nitric acid is 0.3-0.5 mol / L, and the amount of the dilute nitric acid used is 1-2 times the mass of the wet slag of the calcified vanadium extraction tailings.

8. The method for leaching vanadium from calcified vanadium tailings according to claim 1, It is characterized in that In S3, the amount of calcium fluoride used is 2-3% of the mass of the wet slag of the calcified vanadium extraction tailings.

9. The method for extracting vanadium by leaching calcified vanadium tailings according to claim 1, It is characterized in that In S3, the amount of hydrogen peroxide used is 5 to 7 times the amount of all-vanadium substances in the calcified vanadium extraction tailings.

10. The method for extracting vanadium by leaching calcified vanadium tailings according to claim 1, It is characterized in that In S3, the reaction time is 80~100min.

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