Method for removing impurities from carbonated vanadium leach solution

Abstract

The present application belongs to the impurity removal method of carbonated vanadium leaching solution, comprising: adjusting the pH value of the carbonated vanadium leaching solution and then adding zinc source; stirring and heating, filtering, and taking the filtrate, which is ready. The pH value is 10.5-12.5; the zinc source includes one or several of zinc sulfate, zinc chloride, zinc nitrate, zinc oxide and zinc acetate in any ratio; the amount of zinc source added is 6.0-9.0 according to the molar ratio of zinc element to iron element in the carbonated vanadium leaching solution; the heating temperature is 90-100 DEG C. The present application introduces divalent zinc ions into the alkaline carbonated vanadium leaching solution, realizes the purpose of simple process method impurity removal and deep iron removal. The rapid and deep iron removal of the carbonated vanadium leaching solution is realized, the content of iron and zinc in the vanadium solution can be reduced to below 5 ppm, the iron removal does not introduce excessive zinc ions at the same time, the impurity removal effect is excellent, and the end vanadium precipitation process is not affected.

Description

Technical Field

[0001] This invention belongs to the field of vanadium extraction and metallurgical technology, and specifically relates to a method for removing impurities from vanadium carbonate leaching solutions. Background Technology

[0002] Vanadium carbonate leaching solution is a vanadium extraction raw material containing high-valent vanadium, produced by the calcination and roasting-acid leaching process of vanadium slag. This leaching solution contains few impurities; besides small amounts of silicon and phosphorus, the main impurity element is iron. Currently, reported methods for preparing vanadium pentoxide from carbonate leaching solutions all suffer from low purity and excessive levels of certain impurities (mainly iron). Therefore, removing iron impurities is the primary technical problem to be solved in the purification of vanadium carbonate leaching solutions. Because Fe... 3+ In solution, it dissolves as the pH of the solution increases, forming the corresponding ferrate, with the molecular formula [Fe(OH)4]. - Therefore, iron removal can be achieved by adjusting the pH of the vanadium carbonate leaching solution and heating it to precipitate iron ions in the form of Fe(OH)3. However, this method is difficult to achieve deep iron removal due to the influence of the ion precipitation-equilibrium principle, resulting in high iron content and low quality in the subsequent vanadium products. Therefore, for the current field of vanadium production from vanadium carbonate leaching solution, deep iron and impurity removal is the key to producing higher quality vanadium products.

[0003] The article (Exploration of Iron Removal Process for Vanadium-Containing Leachate [J]. Nonferrous Mining and Metallurgy) proposes using vanadium-containing shale coal as material, leaching with sulfuric acid to obtain the leachate, and employing a neutralization-reduction-solvent extraction process to treat the leachate. The extractant used is P2O4, the co-extractant is TBP, and the diluent is sulfonated kerosene. Single-stage extraction and multi-stage countercurrent extraction are used, ultimately achieving an iron removal rate of over 99% and a vanadium recovery rate of 80%. Although this method has a high iron removal rate, the vanadium recovery rate is low, and the process flow is relatively complex. Patent CN 101538649 B discloses a method for iron removal from acid leaching solution during vanadium extraction from shale coal. First, the pH of the acid leaching solution is adjusted to the range of 2-4 with ammonia water. Then, a mixed extractant is used to extract the solution. The mixed extractant is a mixture of kerosene and P2O4 extractant, where the P2O4 extractant is one or more of monobutyl phosphate, monooctyl phosphate, monohexyl phosphate, and citric acid. After extraction, iron ions in the mixed extractant are back-extracted using dilute sulfuric acid, and the extractant is recycled. This method can only reduce the iron ion concentration in the acid leaching solution by 65-82%, making it a simple and preliminary iron removal method. The iron ion concentration in the raffinate remains high, failing to achieve deep iron removal. Furthermore, extraction methods in industrial production suffer from common problems such as extractant emulsification, the production of a third phase, and the extractant's potential harm to health and volatility.

[0004] In summary, there are few reports on iron removal from vanadium-containing materials, and research on iron removal from vanadium carbonate leaching solutions is virtually nonexistent. When dealing with iron removal from other vanadium-containing materials, extraction methods are the primary approach. However, extraction methods face many common and unresolved problems in industrial applications, such as: expensive extractants, emulsification, flammable and toxic organic solvents, severe environmental pollution, and demanding extraction conditions.

[0005] Based on this, the present invention provides a method for removing impurities from vanadium carbonate leaching solution, which obtains high-quality vanadium products through a simple and low-cost method. Summary of the Invention

[0006] This invention provides a method for removing impurities from vanadium carbonate leaching solutions, thereby solving the problems of high iron removal costs and complex removal methods.

[0007] The objective of this invention is achieved through the following technical solution:

[0008] Methods for removing impurities from vanadium carbonate leaching solutions include:

[0009] After adjusting the pH of the vanadium carbonate leaching solution, a zinc source is added.

[0010] Stir and heat, filter, and collect the filtrate.

[0011] Furthermore, the pH value is 10.5 to 12.5.

[0012] Furthermore, the pH value is 11.

[0013] Furthermore, the pH value is 11.5.

[0014] Furthermore, the zinc source includes one or more of zinc sulfate, zinc chloride, zinc nitrate, zinc oxide, and zinc acetate in any ratio.

[0015] Furthermore, the amount of zinc source added is such that the molar ratio of zinc to iron in the vanadium carbonate leaching solution is 6.0 to 9.0.

[0016] Furthermore, the heating temperature is 90–100°C.

[0017] Furthermore, the heating temperature is 95°C.

[0018] Furthermore, the stirring time is 1 to 6 hours.

[0019] Furthermore, the stirring time is 4 hours.

[0020] The beneficial effects of this invention are:

[0021] This invention achieves the purpose of removing impurities and deeply removing iron through a simple process by introducing divalent zinc ions into an alkaline vanadium carbonate leaching solution. The principles involved are as follows:

[0022] Precipitation promotion: Divalent zinc ions hydrolyze in an alkaline environment to form zinc hydroxide precipitate (or by adding zinc oxide, first dissolving zinc oxide in a strong alkali to form sodium zincate solution, which then hydrolyzes in a lower pH solution to form zinc hydroxide); simultaneously, ferric ions, impurities in the original solution, also hydrolyze to form ferric hydroxide precipitate; utilizing the principle that the solubility product constant of zinc hydroxide is much greater than that of ferric hydroxide, and that ferric ions preferentially precipitate divalent zinc ions, the precipitation of zinc hydroxide promotes the precipitation of ferric ions. The chemical formula is as follows:

[0023] Zn 2+ +OH - →Zn(OH)2↓

[0024] Fe 3+ +OH - →Cr(OH)3↓

[0025] If zinc oxide is used, the chemical formula for producing zinc hydroxide is as follows:

[0026] ZnO+2NaOH→Na2ZnO2+H2O or ZnO+2NaOH+H2O=Na2[Zn(OH)4]

[0027] Na2ZnO2+2H2O→Zn(OH)2↓+2NaOH or Na2[Zn(OH)4]→Zn(OH)2↓+2NaOH

[0028] Coprecipitation: Divalent zinc ions and trivalent iron ions also undergo a coprecipitation reaction during hydrolysis, forming coprecipitates of ferric hydroxide and zinc hydroxide. The precipitates of the two ions interact and promote each other, resulting in a synergistic precipitation effect. The chemical formulas are as follows:

[0029] Zn(OH)2+Fe(OH)3→Zn(OH)2·Fe(OH)3↓

[0030] Based on the two effects mentioned above, the addition of divalent zinc ions can achieve the effect of deep iron removal in vanadium carbonate leaching solution.

[0031] This invention achieves rapid and deep iron removal from vanadium carbonate leaching solutions, reducing the iron and zinc content in the vanadium solution to below 5 ppm. It removes iron without introducing excessive zinc ions, resulting in excellent impurity removal and no impact on the subsequent vanadium precipitation process.

[0032] The rapid and deep iron removal method proposed in this invention is a chemical precipitation method. It has the advantages of simple and easy-to-use process, low equipment requirements, convenient operation, short process, easy to scale up operation, and cheap zinc source, making it very suitable for industrial production.

[0033] Using the filtrate obtained by removing impurities in this invention as the raw material for vanadium extraction, the purity of vanadium pentoxide obtained through the downstream vanadium precipitation process is ≥99.9%, which solves the problem of high cost in the preparation process of high-purity vanadium pentoxide.

[0034] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures pointed out in the description, claims and drawings. Attached Figure Description

[0035] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0036] Figure 1 A flowchart of a method for removing impurities from a vanadium carbonate leaching solution according to an embodiment of the present invention is shown. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0038] like Figure 1 As shown, the method for removing impurities from vanadium carbonate leaching solution includes:

[0039] After adjusting the pH of the vanadium carbonate leaching solution, a zinc source is added.

[0040] Stir and heat, filter, and collect the filtrate.

[0041] The pH value is 10-12. When the pH is too low, Fe 3+ and Zn 2+ Incomplete hydrolysis results in a low iron removal rate; when the pH is too high, some hydroxides will dissolve again in the alkaline solution, which will actually increase the amount of impurities.

[0042] The zinc source is added in an amount that is such that the molar ratio of zinc to iron in the vanadium carbonate leaching solution is 6.0–9.0. 2+ Insufficient iron removal due to low Zn content 2+Excessive concentration will introduce too much zinc, increasing material consumption and causing Zn concentration in the solution to rise. 2 + Exceeding the standard;

[0043] The zinc source is one or a mixture of several of the following in any proportion: zinc sulfate (ZnSO4·7H2O), zinc chloride (ZnCl2), zinc nitrate (Zn(NO3)2·6H2O), zinc oxide (ZnO), and zinc acetate (Zn(CH3COO)2);

[0044] The heating temperature is 90–100°C. Higher temperatures accelerate the Fe… 3+ The water leaching rate, zinc-iron co-precipitation rate, and iron removal rate were improved.

[0045] The stirring time is 1–6 hours. If the time is too short, Fe… 3+ and Zn 2+ Incomplete reaction affects the final iron removal rate, and excessive time increases energy consumption and cost.

[0046] Example 1

[0047] 500 ml of vanadium carbonate leaching solution containing 0.057 g / L of iron was measured. The pH of the vanadium carbonate leaching solution was adjusted to 10.5 with sodium hydroxide. 0.88 g of ZnSO4·7H2O was added, and the mixture was stirred at 90 °C for 1 h. After the reaction was completed, the filter cake and filtrate were obtained by filtration. The Fe content in the filtrate was measured to be 4.8 ppm and the Zn content was 1.7 ppm.

[0048] Comparative Example 1

[0049] 500 ml of vanadium carbonate leaching solution containing 0.057 g / L of iron was measured. The pH of the vanadium carbonate leaching solution was adjusted to 10.5 with sodium hydroxide. The solution was stirred and reacted at 90 °C for 1 h. After the reaction was completed, the filter cake and filtrate were obtained by filtration. The Fe content in the filtrate was measured to be 0.034 g / L.

[0050] Example 2

[0051] 500 ml of vanadium carbonate leaching solution containing 0.102 g / L of iron was measured. The pH of the vanadium carbonate leaching solution was adjusted to 11 with sodium hydroxide. 0.87 g of ZnCl2 was added, and the mixture was stirred at 95 °C for 2 h. After the reaction was completed, the filter cake and filtrate were obtained by filtration. The Fe content in the filtrate was measured to be 3.3 ppm and the Zn content was 2.4 ppm.

[0052] Comparative Example 2

[0053] 500 ml of vanadium carbonate leaching solution containing 0.102 g / L of iron was measured. The pH of the vanadium carbonate leaching solution was adjusted to 11 with sodium hydroxide. The solution was stirred and reacted at 90 °C for 4 h. After the reaction was completed, the filter cake and filtrate were obtained by filtration. The Fe content in the filtrate was measured to be 0.042 g / L.

[0054] Example 3

[0055] 500 ml of vanadium carbonate leaching solution containing 0.088 g / L of iron was measured. The pH of the vanadium carbonate leaching solution was adjusted to 11.5 with sodium hydroxide. 1.87 g of Zn(NO3)2·6H2O was added, and the mixture was stirred at 98 °C for 4 h. After the reaction was completed, the filter cake and filtrate were obtained by filtration. The Fe content in the filtrate was measured to be 1.4 ppm and the Zn content was 3.8 ppm.

[0056] Example 4

[0057] 500 ml of vanadium carbonate leaching solution containing 0.057 g / L of iron was measured. The pH of the vanadium carbonate leaching solution was adjusted to 12 with sodium hydroxide. 0.96 g of ZnCl2 was added, and the mixture was stirred at 100 °C for 6 h. After the reaction was completed, the filter cake and filtrate were obtained by filtration. The Fe content in the filtrate was measured to be 1.8 ppm and the Zn content was 4.9 ppm.

[0058] Example 5

[0059] 500 ml of vanadium carbonate leaching solution containing 0.034 g / L of iron was measured. The pH of the vanadium carbonate leaching solution was adjusted to 10.8 with sodium hydroxide. 0.2 g of ZnO was weighed, dissolved in a small amount of alkaline solution, and added to the vanadium carbonate leaching solution. The mixture was stirred and reacted at 100 °C for 3.5 h. After the reaction was completed, the filter cake and filtrate were obtained. The Fe content in the filtrate was measured to be 2.5 ppm and the Zn content was measured to be 2.8 ppm.

[0060] A comparison of the Fe and Zn content data in the filtrates obtained from Examples 1-5 and Comparative Examples 1-2 shows that:

[0061] The iron and zinc content in the filtrate obtained by the iron removal methods used in Examples 1-4 was reduced to below 5 ppm. No excessive zinc ions were introduced during the iron removal process, resulting in excellent impurity removal and no impact on the downstream vanadium precipitation process.

[0062] Furthermore, the iron content in the filtrate obtained in Examples 1-2 is much lower than the iron content in the filtrate obtained in Comparative Examples 1-2.

[0063] Vanadium pentoxide was prepared by back-end vanadium precipitation according to Table 1, and the purity of the obtained vanadium pentoxide was tested. The purity results are shown in Table 1.

[0064] Table 1

[0065]

[0066] As can be seen from the data in Table 1, using the filtrate obtained in Examples 1-5 as the raw material for vanadium extraction, the purity of vanadium pentoxide obtained through the downstream vanadium precipitation process is ≥99.9%.

[0067] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for removing impurities from vanadium carbonate leaching solution, characterized in that, include: After adjusting the pH of the vanadium carbonate leaching solution, a zinc source is added. Stir and heat, filter, and collect the filtrate; The amount of zinc source added is based on a molar ratio of zinc to iron in the vanadium carbonate leaching solution of 6.0 to 9.

0. The heating temperature is 90~100℃.

2. The method for removing impurities from vanadium carbonate leaching solution according to claim 1, characterized in that, The pH value is 10.5~12.

5.

3. The method for removing impurities from vanadium carbonate leaching solution according to claim 1 or 2, characterized in that, The pH value is 11.

4. The method for removing impurities from vanadium carbonate leaching solution according to claim 1 or 2, characterized in that, The pH value is 11.

5.

5. The method for removing impurities from vanadium carbonate leaching solution according to claim 1, characterized in that, The zinc source includes one or more of zinc sulfate, zinc chloride, zinc nitrate, zinc oxide, and zinc acetate in any ratio.

6. The method for removing impurities from the vanadium carbonate leaching solution according to any one of claims 1, 2, and 5, characterized in that, The heating temperature is 95°C.

7. The method for removing impurities from the vanadium carbonate leaching solution according to any one of claims 1, 2, and 5, characterized in that, The stirring time is 1 to 6 hours.

8. The method for removing impurities from the vanadium carbonate leaching solution according to any one of claims 1, 2, and 5, characterized in that, The stirring time is 4 hours.

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