Treatment method of titanium concentrate acid leaching filtrate

Abstract

The invention discloses a treatment method of a titanium concentrate acid leaching filtrate. The treatment method comprises the following steps: (1) titanium concentrate acid leaching: after titanium concentrate acid leaching, filtering to obtain titanium dioxide and a primary filtrate; (2) salting out the primary filtrate: introducing hydrogen chloride gas into the primary filtrate, then cooling and crystallizing, and filtering to obtain ferrous chloride crystals and secondary filtrate; (3) secondary filtrate is reused for titanium concentrate acid leaching; (4) roasting the ferrous chloride crystal obtained in the step (2) to obtain iron oxide red and hydrogen chloride gas, and recycling the hydrogen chloride gas for salting out the primary filtrate; (5) circulating the steps (1)-(4) until the reaction is finished; according to the method, double systems of cyclic utilization of the titanium concentrate pickle liquor and cyclic utilization of the hydrogen chloride gas are formed, the utilization rate of iron in the titanium concentrate and the utilization rate of the hydrogen chloride gas are improved, the utilization rate of iron is larger than 93%, and the utilization rate of the hydrogen chloride gas is larger than 99%.

Description

Technical Field

[0001] The invention relates to the technical field of acid leaching filtrate treatment, and more specifically, to a method for treating titanium concentrate acid leaching filtrate. Background Art

[0002] At present, the mature processes for the industrial production of titanium dioxide are the sulfuric acid method and the chlorination method. The advantages of the chlorination method of titanium dioxide production are short process and high product quality, but it will produce a large amount of waste liquid. The waste liquid also contains some valuable metal substances, such as ferrous ions, manganese ions, aluminum ions, etc. If the waste liquid is discharged directly without treatment, it is easy to cause environmental pollution. Using a treatment agent to treat it before discharging it will increase the treatment cost on the one hand, and cause a waste of resources on the other hand. Therefore, it is of great significance to recycle the waste liquid of titanium dioxide produced by the chlorination method in industry.

[0003] The preparation of titanium dioxide by the hydrochloric acid method is mainly done by acid leaching titanium concentrate or titanium slag with hydrochloric acid. The iron content in titanium concentrate or titanium slag is second only to titanium. Therefore, there are a large number of ferrous ions in the waste liquid after acid leaching. Ferrous chloride is widely used in lithium batteries, pigments, and water treatment fields. If the ferrous ions in the waste liquid are separated to obtain ferrous chloride and then applied to other fields, it will not only make full use of resources but also reduce the processing costs of enterprises.

[0004] In the prior art, there have been some studies on separating ferrous chloride from waste liquid after acid leaching. However, the waste liquid after separating ferrous chloride still uses conventional acid waste liquid treatment methods, which has certain treatment costs for enterprises and also adds burden to the environment.

[0005] At the same time, there are two main methods for producing red iron oxide from ferrous chloride: dry method and wet method. The dry method is mainly calcination. During the calcination process, waste gas containing a large amount of hydrogen chloride gas will be produced. If these gases are purified and discharged by conventional methods, it will cause a large amount of resource waste and increase the production burden of the enterprise.

[0006] Therefore, how to make full use of the waste liquid after separation of ferrous chloride and the waste gas generated in the process of producing red iron oxide from ferrous chloride is of great significance to enterprise production and environmental protection. Summary of the invention

[0007] In view of the above, the present invention provides a method for treating titanium concentrate acid leaching filtrate, forming a dual system of recycling titanium concentrate acid leaching solution and recycling hydrogen chloride gas, thereby solving the problem of waste of iron resources in titanium concentrate and the problem of treating hydrogen chloride waste gas in the production process of red iron oxide.

[0008] The present invention provides a method for treating a titanium concentrate acid leaching filtrate, the specific steps of which include:

[0009] (1) Acid leaching of titanium concentrate: The titanium concentrate is acid-leached with hydrochloric acid and then filtered to obtain titanium dioxide and a primary filtrate;

[0010] (2) Salting out of the primary filtrate: introducing hydrogen chloride gas into the primary filtrate, followed by cooling and crystallization, and filtering to obtain ferrous chloride crystals and a secondary filtrate;

[0011] (3) The secondary filtrate is recycled for acid leaching of titanium concentrate;

[0012] (4) calcining the ferrous chloride crystals obtained in step (2) to obtain red iron oxide and hydrogen chloride gas, wherein the hydrogen chloride gas is recycled for salting out of the primary filtrate;

[0013] (5) Repeat steps (1) to (4) until the reaction is complete.

[0014] During the circulation process, the magnesium content in the secondary filtrate is ≤15g / L.

[0015] During the circulation process, the iron content in the secondary filtrate is 40-70 g / L.

[0016] During the circulation process, the mass concentration of hydrogen chloride in the secondary filtrate is 25-29%.

[0017] During the salting out process of the primary filtrate, most of the iron in the primary filtrate is precipitated as ferrous chloride crystals, and a small amount of iron remains in the secondary filtrate. At the same time, since hydrogen chloride gas is introduced during the salting out process, more hydrogen chloride remains in the secondary filtrate, which has a higher acid concentration. The secondary filtrate is reused for acid leaching of titanium concentrate, so that the iron and hydrogen chloride are fully utilized. In addition, the hydrogen chloride content in the secondary filtrate is just suitable for the acid leaching reaction of titanium concentrate, and the metal chlorides such as iron contained therein increase the boiling point of the solution, which is beneficial to the acid leaching reaction of the titanium concentrate.

[0018] In addition, the typical main components and their contents of titanium concentrate are TiO246.27%, FeO 33.66%, Fe2O35.91%, SiO24.85%, Al2O31.93%, CaO 1.23%, MgO 6.62%, MnO 0.63%. After the titanium concentrate is acid-leached and filtered, titanium dioxide and silicon dioxide in the titanium concentrate are separated, and the obtained primary filtrate is mainly iron and other non-titanium-iron metal elements. The secondary filtrate obtained after the salting out of the primary filtrate not only retains a small amount of iron, but also other non-titanium-iron metal elements, among which the content of magnesium is the highest among other non-titanium-iron metal elements. In the process of recycling the secondary filtrate for acid leaching of titanium concentrate, the iron element in the secondary filtrate will precipitate during the salting out of the primary filtrate and will not accumulate continuously, while other non-titanium-iron metal elements will accumulate continuously. When the magnesium content in the secondary filtrate is greater than 15 g / L, the salt content in the solution will be too high, affecting the leaching of titanium dioxide. Therefore, it is necessary to keep the magnesium content in the recycled secondary filtrate ≤15 g / L. When it is greater than 15 g / L, it will no longer be recycled for acid leaching of titanium concentrate.

[0019] The purity of the hydrogen chloride gas obtained in step (4) is 100 to 250 g / m 3 .

[0020] The ferrous chloride crystals obtained in step (2) are roasted to obtain red iron oxide and hydrogen chloride gas, and the chemical reaction is: 4FeCl2+O2+4H2O=2Fe2O3+8HCl. The obtained hydrogen chloride gas has high purity and contains only oxygen and nitrogen but no other impurity gases. It is reused in the salting out process of the primary filtrate, and no new impurities are generated or affect the crystallization of ferrous chloride, and the hydrogen chloride gas is fully utilized.

[0021] The titanium concentrate acid leaching is to feed the titanium concentrate and hydrochloric acid in a mass volume ratio of 1:3, then heat to 90-120°C, leaching for 6-8 hours, and filtering after cooling to obtain titanium dioxide and a primary filtrate.

[0022] During the salting out of the primary filtrate, when the mass concentration of hydrogen chloride in the filtrate is 25-29%, the introduction of hydrogen chloride gas is stopped, and then the filtrate is cooled to 10-15° C., ferrous chloride is crystallized, and ferrous chloride crystals and a secondary filtrate are obtained by filtration.

[0023] Hydrogen chloride gas is introduced into the primary filtrate to make the ferrous ions and impurity ions in the solution fully react with hydrogen chloride to form ferrous chloride. At the same time, hydrogen chloride and ferrous chloride have a common ion effect, which can increase the crystallization amount and grain growth rate of ferrous chloride and reduce the solubility of ferrous chloride, so that ferrous chloride is precipitated at 10-15°C; and the secondary filtrate has a higher hydrogen chloride content, which can be used for acid leaching of titanium concentrate.

[0024] During the circulation process, the mass concentration of hydrogen chloride in the primary filtrate is 8-15%.

[0025] During the circulation process, the iron content in the primary filtrate is 120-170 g / L, the magnesium content is 1-15 g / L, the calcium content is 1-5 g / L, and the manganese content is 1-5 g / L.

[0026] During the circulation process, the temperature of the primary filtrate is maintained at 40-60°C while absorbing the hydrogen chloride gas.

[0027] The utilization rate of iron in titanium concentrate is greater than 93%.

[0028] The utilization rate of hydrogen chloride is greater than 99%.

[0029] The invention introduces hydrogen chloride gas into the primary filtrate after acid leaching and filtration of titanium concentrate, and then after precipitating ferrous chloride crystals, the secondary filtrate obtained by filtration is reused in the titanium concentrate acid leaching, so as to form a recycling system of the titanium concentrate acid leaching liquid, so that not only the hydrogen chloride in the secondary filtrate is fully utilized, but also the iron element in the filtrate after the acid leaching and filtration of the titanium concentrate is continuously enriched and precipitated, so as to improve the utilization rate of iron in the titanium concentrate, and finally the utilization rate of iron is greater than 93%; at the same time, the hydrogen chloride gas obtained in the process of roasting the ferrous chloride crystals obtained by salting out the primary filtrate into red iron oxide is reused in the salting out of the primary filtrate, so that the hydrogen chloride gas is fully utilized; the invention forms a dual system of recycling the titanium concentrate acid leaching liquid and recycling the hydrogen chloride gas, so as to improve the utilization rate of iron and hydrogen chloride in the titanium concentrate, so that the utilization rate of hydrogen chloride is greater than 99%, so as to achieve full utilization of various resources, solve the problem of waste gas treatment in the production process of red iron oxide, and reduce the production cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 Process flow chart of the present invention. DETAILED DESCRIPTION

[0031] The embodiments of the present application will be described in more detail below. The application can be implemented in various forms, and should not be construed as being limited to the embodiments set forth herein, but rather these embodiments are provided to provide a more thorough and complete understanding of the present application. It should be understood that the embodiments of the present application are only for exemplary purposes and are not intended to limit the scope of protection of the present application.

[0032] The embodiments of the present invention are as follows, and the specific steps include:

[0033] (1) Acid leaching of titanium concentrate: After acid leaching of titanium concentrate, titanium dioxide and primary filtrate are obtained by filtration;

[0034] (2) Salting out the primary filtrate: introducing hydrogen chloride gas into the primary filtrate, followed by cooling and crystallization, and filtering to obtain ferrous chloride crystals and a secondary filtrate; wherein the secondary filtrate has a magnesium content of ≤15 g / L, an iron content of 40-70 g / L, and a hydrogen chloride content of 25-29%;

[0035] (3) The secondary filtrate is recycled for acid leaching of titanium concentrate;

[0036] (4) The ferrous chloride crystals obtained in step (2) are roasted to obtain red iron oxide and hydrogen chloride gas, and the hydrogen chloride gas is recycled for salting out of the primary filtrate, wherein the purity of the hydrogen chloride gas is 100 to 250 g / m 3 ;

[0037] (5) Repeat steps (1) to (4) until the reaction is complete.

[0038] Comparative Example: The secondary filtrate was not reused for acid leaching of titanium concentrate.

[0039] Table 1 shows the specific implementation conditions and test results of the embodiments and comparative examples, which prove that the present invention improves the utilization rate of iron in titanium concentrate to be greater than 93%. Compared with the case where the secondary filtrate is not reused, the utilization rate of iron is increased by more than 2 times. At the same time, the utilization rate of hydrogen chloride includes the hydrogen chloride in the hydrochloric acid during acid leaching and the hydrogen chloride gas introduced during salting out. It can be seen from Table 2 that the utilization rate of hydrogen chloride in the present invention is greater than 99%, so that hydrogen chloride is fully recycled. A dual system of recycling titanium concentrate acid leaching solution and recycling hydrogen chloride gas is formed, which realizes the full utilization of various resources and reduces production costs.

[0040] When the secondary filtrate is not reused, the utilization rate of hydrogen chloride is low, because the secondary filtrate still contains a large amount of hydrogen chloride, which is not fully utilized, greatly reducing the utilization rate of hydrogen chloride and causing waste of resources; at the same time, the non-reuse of the secondary filtrate reduces the content of magnesium and iron, because in the process of recycling, the magnesium and iron in the secondary filtrate will also be recycled, so the magnesium and iron content in the recycled filtrate of the embodiment is higher than that of the comparative example; when the primary filtrate absorbs hydrogen chloride gas and precipitates ferrous chloride crystals, a small amount of magnesium chloride will also be precipitated, and a small amount of loss will also occur during the filtration process, so the magnesium content in the secondary filtrate will be reduced.

[0041] Table 1 Specific implementation conditions and test results of the embodiments and comparative examples

[0042]

[0043] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in this application, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A method for treating a titanium concentrate acid leaching filtrate, characterized in that: The specific steps include: (1) Acid leaching of titanium concentrate: The titanium concentrate is acid-leached with hydrochloric acid and then filtered to obtain titanium dioxide and a primary filtrate; (2) Salting out of the primary filtrate: introducing hydrogen chloride gas into the primary filtrate, followed by cooling and crystallization, and filtering to obtain ferrous chloride crystals and a secondary filtrate; (3) The secondary filtrate is recycled for acid leaching of titanium concentrate; (4) calcining the ferrous chloride crystals obtained in step (2) to obtain red iron oxide and hydrogen chloride gas, wherein the hydrogen chloride gas is recycled for salting out of the primary filtrate; (5) Repeat steps (1) to (4) until the reaction is complete.

2. The method for treating the titanium concentrate acid leaching filtrate according to claim 1, characterized in that: During the circulation process, the iron content in the secondary filtrate is 40-70 g / L.

3. The method for treating the titanium concentrate acid leaching filtrate according to claim 1, characterized in that: During the circulation process, the magnesium content in the secondary filtrate is ≤15g / L.

4. The method for treating the titanium concentrate acid leaching filtrate according to claim 1, characterized in that: During the circulation process, the mass concentration of hydrogen chloride in the secondary filtrate is 25-29%.

5. The method for treating the titanium concentrate acid leaching filtrate according to claim 1, characterized in that: The purity of the hydrogen chloride gas obtained in step (4) is 100 to 250 g / m 3 .

6. The method for treating the titanium concentrate acid leaching filtrate according to claim 1, characterized in that: The titanium concentrate acid leaching is to feed the titanium concentrate and hydrochloric acid in a mass volume ratio of 1:3, then heat to 90-120°C, leaching for 6-8 hours, and filtering after cooling to obtain titanium dioxide and a primary filtrate.

7. The method for treating the titanium concentrate acid leaching filtrate according to claim 1, characterized in that: During the salting out of the primary filtrate, when the mass concentration of hydrogen chloride in the filtrate is 25-29%, the introduction of hydrogen chloride gas is stopped, and then the filtrate is cooled to 10-25° C. to crystallize ferrous chloride, and ferrous chloride crystals and a secondary filtrate are obtained by filtration.

8. A method for treating a titanium concentrate acid leaching filtrate according to any one of claims 1 to 7, characterized in that: During the circulation process, the mass concentration of hydrogen chloride in the primary filtrate is 8-15%.

9. A method for treating a titanium concentrate acid leaching filtrate according to any one of claims 1 to 7, characterized in that: During the circulation process, the iron content in the primary filtrate is 120-170 g / L, the magnesium content is 1-15 g / L, the calcium content is 1-5 g / L, and the manganese content is 1-5 g / L.

10. A method for treating a titanium concentrate acid leaching filtrate according to any one of claims 1 to 7, characterized in that: During the circulation process, the temperature of the primary filtrate is maintained at 40-60°C while absorbing the hydrogen chloride gas.

11. The method for treating the titanium concentrate acid leaching filtrate according to claim 1, characterized in that: The utilization rate of iron in titanium concentrate is greater than 93%.

12. The method for treating the titanium concentrate acid leaching filtrate according to claim 1, characterized in that: The utilization rate of hydrogen hydride is greater than 99%.

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