Production process for optimizing purity of APT (ammonium paratungstate) product
By combining the secondary crystallization process with additives and temperature control, the problem of insufficient purity of APT products was solved, and the production of APT with high purity and high crystallization rate was achieved, which is suitable for industrial production.
Patent Information
- Application Number
- CN202511135171.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-14
- Publication Date
- 2025-10-17
- Estimated Expiration
- Not applicable · inactive patent
AI Technical Summary
In the existing APT production process, the impurities remaining in the solution after the first crystallization affect the final purity of APT and have not yet been effectively removed.
The secondary crystallization process is introduced and combined with specific additives or temperature control to optimize the crystallization conditions, including adding ammonium chloride or sodium chloride as additives, controlling the solution temperature and stirring speed, and performing secondary crystallization.
The purity and crystallization rate of APT products are significantly improved, with the purity increased from 99.5% to over 99.6%, and the crystallization rate increased from 94% to 98%. The crystal morphology and particle size distribution are also optimized, making it suitable for large-scale industrial production.
Smart Images
Figure CN120794014A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the field of improving the purity of APT products, and in particular to a production process for optimizing the purity of APT products. BACKGROUND
[0002] Ammonium paratungstate (APT) is an important intermediate product in the process of tungsten hydrometallurgy, and its purity directly affects the quality of subsequent tungsten products. In the existing APT production process, the purity of the APT product after primary crystallization can meet certain standards, but there is still room for further improvement. In particular, after primary crystallization, the impurities remaining in the solution can still affect the final purity of APT.
[0003] Therefore, it is necessary to propose a production process for optimizing the purity of APT products to solve the above problems. SUMMARY
[0004] The purpose of the present application is to provide a production process for optimizing the purity of APT products to solve the problem that impurities remaining in the solution after primary crystallization can still affect the final purity of APT.
[0005] To achieve the above purpose, the present application provides the following technical solution: a production process for optimizing the purity of APT products, comprising the following steps:
[0006] S101: After ion exchange and impurity removal, the ammonium tungstate solution is used as a primary crystallization feed solution, the pH value of the solution is controlled to be not less than 12, and the solution is fed into a vacuum stirring evaporative crystallizer for primary crystallization;
[0007] S102: After primary crystallization is completed, the APT crystallization product is taken out, and the remaining solution is subjected to secondary crystallization;
[0008] S103: During secondary crystallization, a specific additive is added to the remaining solution or the temperature is controlled to promote the full progress of secondary crystallization.
[0009] Preferably, the additive is ammonium chloride or sodium chloride, and the concentration of the additive is controlled to be in the range of 12-13 g / L.
[0010] Preferably, during secondary crystallization, the solution temperature is controlled to be in the range of 65-85℃, and the stirring speed is 60-80 r / min.
[0011] Preferably, the secondary crystallization time is 2.5-3 hours.
[0012] Preferably, during secondary crystallization, no additive is added, and the temperature is gradually reduced from 75℃ to 60℃ only by controlling the temperature.
[0013] Technical effects and advantages of the present application:
[0014] 1、The secondary crystallization process in the present application can significantly improve the purity of APT products by introducing a secondary crystallization process and combining with specific additives or temperature control. The purity of APT products after primary crystallization is usually around 99.5%, while after secondary crystallization, the purity can be improved to more than 99.6%, even to 99.8%, which shows that the secondary crystallization process can effectively remove impurities in the solution, further optimizing the quality of APT products.
[0015] 2、The secondary crystallization process in the present application not only improves the purity of APT products, but also significantly improves the crystallization rate. The crystallization rate after primary crystallization is usually between 94% and 96%, while after secondary crystallization, the crystallization rate can be improved to more than 96%, even to 98%, which shows that the secondary crystallization process can make full use of the remaining APT components in the solution, improve production efficiency and reduce resource waste.
[0016] 3、The secondary crystallization process of the present application is simple to operate and easy to implement, without the need for complex equipment and high-cost reagents. By adding common additives or controlling temperature changes, the optimization effect of secondary crystallization can be achieved, which makes the present application have high economic efficiency and practicality, suitable for large-scale industrial production.
[0017] 4、The secondary crystallization process in the present application improves the purity and crystallization rate of APT products without introducing new impurities or harmful substances, meeting the development requirements of green chemistry. By optimizing the crystallization conditions, the precipitation of impurities is reduced, and the potential impact on the environment is reduced.
[0018] 5、The secondary crystallization process in the present application can further optimize the crystallization morphology and particle size distribution of APT products, making the products have more regular hexahedral morphology and more uniform particle size distribution, which not only improves the appearance quality of the products, but also enhances the use performance of the products, making them more suitable for subsequent processing and application. BRIEF DESCRIPTION OF DRAWINGS
[0019] Figure 1 The production process flow chart for optimizing the purity of APT products. DETAILED DESCRIPTION
[0020] The present application provides a production process for optimizing the purity of APT products as shown in Figure 1
[0021] Example 1
[0022] After the primary crystallization is completed, the remaining solution is subjected to secondary crystallization.
[0023] First, ammonium chloride (NH4CI) is added to the remaining solution to control the Cl- concentration in the solution at 12 g / L. By precisely controlling the concentration of the additive, it is ensured that the impurity ions in the solution can undergo complexation reactions with Cl- to generate complex compounds that are easily soluble in water, thereby inhibiting the precipitation of impurities during secondary crystallization.
[0024] Next, the solution temperature is maintained at 65-75°C. This temperature range ensures that the complexation reactions of impurities in the solution proceed sufficiently, while avoiding excessive evaporation of the solution due to high temperatures, which would affect the crystallization effect.
[0025] The secondary crystallization time is 3 hours, and the stirring speed is 80 r / min. By controlling the stirring speed, it is ensured that the components in the solution are uniformly mixed, promoting the uniform progress of the crystallization process.
[0026] Finally, through secondary crystallization, the impurities in the solution are further removed, increasing the purity of the APT product from 99.5% after primary crystallization to 99.8%, and the crystallization rate from 96% to 98%.
[0027] Example 2
[0028] After primary crystallization, the remaining solution is subjected to secondary crystallization.
[0029] Sodium chloride (NaCI) is added to the remaining solution to control the Cl- concentration in the solution at 13 g / L.
[0030] The addition of sodium chloride not only allows complexation reactions with impurity ions in the solution, but also adjusts the ionic strength of the solution.
[0031] The crystallization environment is further optimized by maintaining the solution temperature at 70-80°C. This temperature range is beneficial for the complexation reactions of impurity ions with Cl-, and also facilitates the secondary crystallization of APT. The secondary crystallization time is 2.5 hours, and the stirring speed is 70 r / min. By controlling the stirring speed, it is ensured that the components in the solution are uniformly mixed, promoting the uniform progress of the crystallization process.
[0032] Finally, through secondary crystallization, the impurities in the solution are further removed, increasing the purity of the APT product from 99.4% after primary crystallization to 99.7%, and the crystallization rate from 95% to 97%.
[0033] Example 3
[0034] After primary crystallization, the remaining solution is subjected to secondary crystallization.
[0035] Without adding any additives, the temperature of the remaining solution is gradually reduced from 75°C to 60°C by controlling the temperature change.
[0036] By gradually reducing the temperature, the natural cooling process is simulated, allowing the APT in the solution to slowly crystallize at lower temperatures, thereby improving the purity and quality of the crystallization.
[0037] The secondary crystallization time is 3 hours, and the stirring speed is 60 r / min.
[0038] By controlling the stirring speed, the mixture of each component in the solution is ensured to be uniform, promoting the uniform progress of the crystallization process.
[0039] Finally, through secondary crystallization, further impurities in the solution are removed, and the purity of the APT product is improved from 99.3% in the first crystallization to 99.6%, and the crystallization rate is improved from 94% to 96%.
[0040] Table 1 Comparison of purity and crystallization rate of primary and secondary crystallization
[0041]
[0042] Table 2 Effect of different additives on secondary crystallization
[0043]
[0044] From Table 1 and Table 2, we can see that:
[0045] The selection and concentration control of additives are key in the secondary crystallization process.
[0046] By adding ammonium chloride (NH4Cl) or sodium chloride (NaCl), the ionic strength and complexation reaction in the solution can be effectively adjusted, thereby inhibiting the precipitation of impurity ions.
[0047] Precise control of the concentration of additives can ensure the full progress of the complexation reaction, while avoiding changes in the properties of the solution caused by excessive additives.
[0048] Temperature control is another key factor in the secondary crystallization process.
[0049] By precisely controlling the crystallization temperature, the crystallization environment can be optimized, and the purity and quality of the crystallization can be improved.
[0050] In Examples 1 and 2, by maintaining the temperature at 65-80℃, the complexation reaction between impurity ions and Cl- is ensured to proceed fully; in Example 3, by gradually reducing the temperature, the natural cooling process is simulated, further improving the purity and quality of the crystallization.
[0051] The control of stirring speed can ensure the uniform mixing of each component in the solution, promoting the uniform progress of the crystallization process.
[0052] By precisely controlling the stirring speed, local overheating or overcooling of the solution caused by too fast stirring can be avoided, thereby improving the uniformity and quality of the crystallization.
[0053] In Example 1, the stirring speed is 80 r / min; in Example 2, the stirring speed is 70 r / min; and in Example 3, the stirring speed is 60 r / min.
[0054] In summary, by introducing the secondary crystallization process and combining with specific additives or temperature control, the purity and crystallization rate of the APT product can be significantly improved; Examples 1, 2 and 3 all show that the purity and crystallization rate of the APT product after secondary crystallization are improved, and the use of additives further optimizes the crystallization effect, which provides a new technical solution for efficient production of APT and has significant economic and social benefits.
Claims
1. A production process for optimizing the purity of an APT product, characterized in that: The following steps are involved: S101: The ammonium tungstate solution after ion exchange and impurity removal is used as a primary crystallization feed solution, the pH value of the solution is controlled to be not less than 12, and the solution is put into a vacuum stirring evaporation crystallizer for primary crystallization; S102: After the primary crystallization is completed, the APT crystal product is taken out and the remaining solution is subjected to secondary crystallization; S103: During the secondary crystallization process, specific additives are added to the remaining solution or the temperature change is controlled to promote the full progress of the secondary crystallization.
2. A production process for optimizing the purity of an APT product according to claim 1, characterized in that: The additive is ammonium chloride or sodium chloride, and the concentration of the additive is controlled within the range of 12 to 13 g / L.
3. The production process for optimizing the purity of an APT product according to claim 1, characterized in that: During the secondary crystallization process, the solution temperature was controlled within the range of 65-85°C and the stirring speed was 60-80 r / min.
4. The production process for optimizing the purity of an APT product according to claim 1, characterized in that: The secondary crystallization time is 2.5 to 3 hours.
5. The production process for optimizing the purity of an APT product according to claim 1, characterized in that: During the secondary crystallization process, no additives were added, and the temperature was simply controlled to gradually decrease from 75°C to 60°C.