Method for extracting vanadium from calcified vanadium extraction tailings through leaching

Abstract

The invention relates to the technical field of vanadium metallurgy and chemical industry, and discloses a method for extracting vanadium from calcified vanadium extraction tailings through leaching, which comprises the following steps: carrying out chute reselection on the calcified vanadium extraction tailings to obtain coarse-fraction chute reselection slag and fine-fraction chute reselection slag; mixing the coarse-fraction chute reselection slag with ammonium bicarbonate, adding hot water, bubbling, carrying out stirring reaction, and carrying out solid-liquid separation to obtain desulfurized slag; dilute nitric acid, calcium fluoride and hydrogen peroxide are added into the desulfurization residues, solid-liquid separation is conducted after heating reaction, and a vanadium-containing solution and secondary leaching tailings with the low vanadium content are obtained; adding polyferric sulfate into the vanadium-containing solution, stirring to remove impurities, and filtering to obtain qualified vanadium liquid. According to the method, the reselection technology is adopted, 90% or above of calcium sulfate can be directly removed, meanwhile, vanadium can be directly extracted through leaching by adding simple chemical reagents, complex processes such as drying, roasting and re-leaching do not need to be conducted, and the vanadium leaching rate is larger than 65%.

Description

Technical Field

[0001] The invention relates to the technical field of vanadium metallurgy and chemical industry, 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 the fields of metallurgy, chemical industry, national defense, energy, etc. At present, vanadium extraction mainly adopts two processes: calcium roasting-sulfuric acid leaching-ammonium salt vanadium precipitation and sodium roasting-water leaching-ammonium salt vanadium precipitation. Among them, the vanadium slag is subjected to the "calcification roasting-acid leaching" process to produce acid leaching slag. The content of vanadium pentoxide in the vanadium extraction tailings is 1~2%, which exceeds the vanadium content in vanadium-titanium magnetite and is a valuable secondary resource. Therefore, it is necessary to develop new processes to reduce the TV (total vanadium) content in the tailings. At present, many patent documents have studied how to reduce the vanadium content in the tailings, most of which are through methods such as lowering the pH value and roasting the tailings with calcium again.

[0003] At present, the process generally produces vanadium tailings by mixing and roasting with vanadium slag or lime. However, the water content in the calcified vanadium tailings is high, so it is difficult to mix and roast. In addition, the TV content in the tailings is relatively low, so it is difficult to extract vanadium. It can be seen that there is currently no good process route for secondary vanadium extraction from calcified vanadium tailings in China. A better process route for treating calcified vanadium tailings is needed to realize the industrialization of calcified vanadium tailings.

[0004] Therefore, there is a need in the prior art for improving the method for leaching vanadium from calcified vanadium tailings. Summary of the invention

[0005] 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, which extracts vanadium through gravity separation and chemical reagents without going through complicated drying, roasting, re-leaching and other processes.

[0006] Based on the above purpose, the embodiment of 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 then mixes the coarse-grained chute gravity separation slag with ammonium bicarbonate, adds hot water and bubbles, 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, heating for reaction and then performing solid-liquid separation to obtain a vanadium-containing solution and secondary leaching tailings with a low vanadium content; S4: adding polyferric sulfate to the vanadium-containing solution, stirring to remove impurities, and filtering to obtain a qualified vanadium solution.

[0007] In some embodiments, the liquid-to-solid ratio of the vanadium-containing solution to the polyferric sulfate is (500-600): 1 ml / g.

[0008] In some embodiments, in S1, the calcified vanadium extraction tailings has a total iron content of 20-35%, a total vanadium content of 1-2%, a calcium sulfate content of 15-30%, a silicon content of 5-10%, and the remainder is titanium, manganese, aluminum, magnesium, and phosphorus, by mass percentage.

[0009] In some embodiments, in S2, the amount of ammonium bicarbonate used is 2-3% of the mass of the calcified vanadium extraction tailings, and the reaction time is 30-50 min.

[0010] In some embodiments, in S2, the ammonium bicarbonate is mechanically activated by a vibration mill.

[0011] In some embodiments, in S2, the temperature of the hot water used for bubbling is in the range of 30-40°C.

[0012] In some embodiments, in S2, during bubbling, air is continuously introduced into the liquid, and the air flow rate is ≥0.6 L / min.

[0013] In some embodiments, in S3, the amount of dilute nitric acid used is such that the liquid-to-solid ratio of the wet slag of the calcified vanadium extraction tailings is (1:1)~(2:1) ml / g, the amount of calcium fluoride used is 2~3% of the mass of the calcified vanadium extraction tailings, and the amount of hydrogen peroxide used is 5~7 times the amount of total vanadium substance in the vanadium slag, that is, n(H2O2):n(V)=5~7.

[0014] In some embodiments, the concentration of dilute nitric acid is 0.3-0.5 mol / L.

[0015] In some embodiments, in S3, the temperature of the heating reaction is 60-75° C., and the reaction time is 60-100 min.

[0016] The present invention has at least the following beneficial technical effects: The present invention adopts gravity separation technology, which can directly remove more than 90% of calcium sulfate, thereby reducing the subsequent tailings treatment volume by more than 30% (wet weight). At the same time, vanadium can be directly leached and extracted by adding simple chemical reagents without going through complicated drying, roasting, re-leaching and other processes. This not only greatly reduces production costs and reduces environmental pollution, but also the vanadium leaching rate is greater than 65%, and ammonium sulfate can be recovered in the process for subsequent vanadium precipitation. In addition, the entire leaching and vanadium extraction process route is simple, with the characteristics of energy saving, simple operation, and high leaching efficiency, which is convenient for large-scale promotion. 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 This is a schematic diagram of an embodiment of a method for leaching vanadium from calcified vanadium extraction tailings provided by the present invention. DETAILED DESCRIPTION

[0019] 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.

[0020] 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.

[0021] 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.

[0022] like 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 then mixes the coarse-grained chute gravity separation slag with ammonium bicarbonate, adds hot water and bubbles, 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, heating for reaction and then performing solid-liquid separation to obtain a vanadium-containing solution and secondary leaching tailings with a low vanadium content; S4: adding polyferric sulfate to the vanadium-containing solution, stirring to remove impurities, and filtering to obtain a qualified vanadium solution.

[0023] Furthermore, the liquid-to-solid ratio of the vanadium-containing solution to the polyferric sulfate is (500-600): 1 ml / g.

[0024] Furthermore, in S1, the total iron content in the calcified vanadium extraction tailings is 20-35%, the total vanadium content is 1-2%, the calcium sulfate content is 15-30%, the silicon content is 5-10%, and the rest is titanium, manganese, aluminum, magnesium, and phosphorus.

[0025] Furthermore, in S2, the amount of ammonium bicarbonate used is 2-3% of the mass of the calcified vanadium extraction tailings, and the reaction time is 30-50 min.

[0026] Further, in S2, the ammonium bicarbonate is mechanically activated by a vibration mill. The high-frequency vibration of the grinding container is used to make the grinding media and ammonium bicarbonate vibrate at high frequencies in the container. During the vibration process, the grinding media impacts, rubs and grinds the ammonium bicarbonate particles, thereby achieving mechanical activation. This method has a high activation efficiency and can improve the activity of ammonium bicarbonate in a short time. In addition, the most commonly used ball milling method for mechanical activation can also be used. The ammonium bicarbonate is placed in the grinding jar of the ball mill and grinding balls (usually stainless steel balls, agate balls, etc.) are added. When the ball mill is running, the grinding balls collide and rub against the ammonium bicarbonate particles, causing the lattice structure of the ammonium bicarbonate particles to be distorted and defective, thereby achieving the purpose of activation. For example, in a planetary ball mill, the grinding jar rotates around its own axis while also revolving around the central axis. This mode of motion can cause the grinding balls to produce complex motion trajectories in the grinding jar, thereby enhancing the grinding and activation effect of ammonium bicarbonate.

[0027] Further, in S2, the temperature range of the hot water used during bubbling is 30-40° C. During bubbling, air is continuously introduced into the liquid, and the air flow rate is ≥0.6 L / min.

[0028] Further, in S3, the amount of dilute nitric acid is such that the liquid-to-solid ratio of the wet slag of the calcified vanadium extraction tailings is (1:1) to (2:1) ml / g, the amount of calcium fluoride is 2 to 3% of the mass of the calcified vanadium extraction tailings, and the amount of hydrogen peroxide is 5 to 7 times the amount of all-vanadium substances in the vanadium slag, that is, n (H2O2): n (V) = 5 to 7. In some embodiments, the concentration of dilute nitric acid is 0.3 to 0.5 mol / L.

[0029] Furthermore, in S3, the temperature of the heating reaction is 60-75°C, and the reaction time is 60-100 min.

[0030] 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 3 The 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 valences, 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 destroys 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, thereby leaching vanadium into the solution.

[0031] 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.

[0032] 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 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 0.3 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.

[0033] 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%.

[0034] Example 2 Take 500g vanadium extraction tailings (dry weight, 30.65% TFe, 21.79% CaSO4, 1.65% 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 1.8 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.

[0035] 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%.

[0036] Example 3 Take 500g vanadium extraction tailings (dry weight, 29.75% TFe, 22.52% CaSO4, 1.38% 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 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 0.3 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.

[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] Example 4 Take 500g vanadium extraction tailings (dry weight, 28.58% TFe, 21.73% 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 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 0.3 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.

[0039] 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%.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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 leaching vanadium from calcified vanadium tailings, 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 then mixes the coarse-grained chute gravity separation slag with ammonium bicarbonate, adds hot water and performs bubbling, stirs for reaction, and separates the solid and liquid to obtain desulfurized slag; S3: adding dilute nitric acid, calcium fluoride and hydrogen peroxide to the desulfurized slag, heating for reaction and then performing solid-liquid separation to obtain a vanadium-containing solution and secondary leaching tailings with a low vanadium content; S4: adding polyferric sulfate to the vanadium-containing solution, stirring to remove impurities, and filtering to obtain a qualified vanadium solution.

2. The method for leaching vanadium from calcified vanadium tailings according to claim 1, characterized in that: The liquid-to-solid ratio of the vanadium-containing solution to the polymerized ferric sulfate is (500-600): 1 ml / g.

3. The method for leaching vanadium from calcified vanadium tailings according to claim 1, characterized in that: In terms of mass percentage, in S1, the calcified vanadium extraction tailings has a total iron content of 20-35%, a total vanadium content of 1-2%, a calcium sulfate content of 15-30%, a silicon content of 5-10%, and the remainder is titanium, manganese, aluminum, magnesium, and phosphorus.

4. The method for leaching vanadium from calcified vanadium tailings according to claim 1, characterized in that: In S2, the amount of ammonium bicarbonate used is 2-3% of the mass of 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, characterized in that: In S2, the ammonium bicarbonate is mechanically activated by a vibration mill.

6. The method for leaching vanadium from calcified vanadium tailings according to claim 1, characterized in that: In S2, the temperature of the hot water used for bubbling is in the range of 30 to 40°C.

7. The method for leaching vanadium from calcified vanadium tailings according to claim 1, characterized in that: In S2, air is continuously introduced into the liquid during bubbling, and the air flow rate is ≥0.6L / min.

8. The method for leaching vanadium from calcified vanadium tailings according to claim 1, characterized in that: In S3, the amount of dilute nitric acid used is such that the liquid-to-solid ratio of the wet slag of the calcified vanadium extraction tailings is (1:1)~(2:1) ml / g, the amount of calcium fluoride used is 2~3% of the mass of the calcified vanadium extraction tailings, and the amount of hydrogen peroxide used is 5~7 times the amount of total vanadium substance in the vanadium slag, that is, n(H2O2):n(V)=5~7.

9. The method for leaching vanadium from calcified vanadium tailings according to claim 7, characterized in that: The concentration of the dilute nitric acid is 0.3-0.5 mol / L.

10. The method for extracting vanadium by leaching calcified vanadium tailings according to claim 1, characterized in that: In S3, the heating reaction temperature is 60-75°C, and the reaction time is 60-100 min.

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