Potassium iodate waste liquid recovery treatment method
By employing clarification treatment and potassium carbonate conversion processes, the problems of resource waste and environmental risks in the production of potassium iodate have been solved, achieving efficient and environmentally friendly potassium iodate recovery, obtaining high-purity products, and reducing costs.
Patent Information
- Application Number
- CN202511593696.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-03
- Publication Date
- 2026-01-13
AI Technical Summary
In the current potassium iodate production process, the tailings contain about 7% potassium iodate, 25% potassium chloride and potassium chlorate. It is impossible to obtain qualified potassium iodate through simple purification. Moreover, the traditional recycling process has the risks of barium salt toxicity and environmental pollution, resulting in serious waste of resources.
After clarification, the calcium iodate is reacted with a soluble calcium salt solution to form calcium iodate precipitate. It is then converted into potassium iodate by potassium carbonate, avoiding the use of toxic barium salts. Calcium carbonate is used to recover and recycle calcium elements. Impurities are removed by two precipitation separations, and finally, high-purity potassium iodate is obtained by crystallization.
The method achieves the recovery of high-purity potassium iodate with a total recovery rate of over 94%, avoiding the use of barium salts, reducing the consumption of fresh calcium salts, reducing solid waste, conforming to the principles of green chemistry, and reducing process costs.
Smart Images
Figure CN121317643A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of potassium iodate recovery, in particular to a potassium iodate waste liquid recovery treatment method. BACKGROUND
[0002] Potassium iodate is a special additive for iodized salt, and is also an important raw material for iodine-fortified food, iodine-deficiency treatment drugs and iodized feed. At present, most of the potassium iodate production enterprises in China still use pure iodine as raw material to prepare potassium iodate by the method of potassium chlorate oxidation and potassium hydroxide neutralization. After the tail liquid of the production process is concentrated and part of the potassium iodate is recovered, the solution contains about 7% of potassium iodate, 25% of potassium chloride and chlorate, and both the potassium iodate and the potassium chloride have been dissolved to near saturation, which cannot obtain qualified potassium iodate by simple purification. China lacks high-quality iodine resources, and most of the iodine used for producing potassium iodate is imported from abroad, so the resources are valuable, and therefore the reasonable and effective use of iodine is particularly important. If it is not fully recovered and utilized, it will cause a large waste of iodine resources.
[0003] The journal "China Salt" published "Recovery of Potassium Iodate in Iodine-containing Waste Liquid" written by the author Zuo Yixi (2012.1 12-13), which uses barium chloride as a precipitant to obtain barium iodate, which is then converted into iodate by reacting with sulfuric acid, and then neutralized with potassium hydroxide to obtain potassium iodate. Although this process can obtain potassium iodate, it will produce barium sulfate and contain a certain amount of barium iodate and iodate, which has no value for recycling as barium sulfate, and also causes a certain amount of iodine waste, and barium salt is toxic, which poses environmental and safety risks. Therefore, it is of great significance to develop an efficient, environmentally friendly and non-secondary pollution potassium iodate waste liquid recovery process. SUMMARY
[0004] In view of the related technical problems, the present application provides a potassium iodate waste liquid recovery treatment method to solve the above technical problems in the prior art.
[0005] To this end, the specific technical solutions adopted by the present application are as follows: A potassium iodate waste liquid recovery treatment method, comprising: Collecting potassium iodate production waste liquid and clarifying the potassium iodate production waste liquid to obtain a clarified filtrate; Stirring and reacting the obtained clarified filtrate with a pre-configured soluble calcium salt solution to obtain calcium iodate precipitate slurry; Solid-liquid separating the obtained calcium iodate precipitate slurry to obtain calcium iodate filter cake; stirring and reacting the obtained calcium iodate filter cake with a pre-configured potassium carbonate solution and water to obtain a reaction mixed solution; Solid-liquid separating the obtained reaction mixed solution to obtain a potassium iodate solution; and crystallizing the obtained potassium iodate solution to obtain potassium iodate.
[0006] The potassium iodate production waste liquid is clarified to obtain a clarified filtrate, including: The potassium iodate production waste liquid is added with a potassium hydroxide solution, and the pH of the solution is adjusted to 9-10; insoluble impurities are removed by filtration to obtain a clarified filtrate.
[0007] Optionally, the soluble calcium salt solution is a calcium chloride solution.
[0008] Optionally, the amount of the soluble calcium salt solution added is 100%-110% of the theoretical calculation amount.
[0009] The obtained calcium iodate filter cake is stirred with a previously prepared potassium carbonate solution and water to obtain a reaction mixture solution, including: The obtained calcium iodate filter cake is added to water and stirred with a potassium carbonate solution until the pH of the mixture solution is 10-11 to obtain a reaction mixture solution.
[0010] Optionally, the reaction temperature during the stirring reaction with the potassium carbonate solution is 50-90°C, and the reaction time is 30-60 minutes.
[0011] Optionally, the amount of the potassium carbonate solution added is 105%-115% of the theoretical calculation amount.
[0012] The obtained potassium iodate solution is crystallized to obtain potassium iodate, including: The obtained potassium iodate solution is sequentially subjected to filtration, heating and concentration, cooling and crystallization, suction filtration, and drying to obtain potassium iodate.
[0013] In addition, the potassium iodate waste liquid recovery processing method further includes: The calcium carbonate filter cake generated when the reaction mixture solution is obtained is mixed with a previously prepared hydrochloric acid to obtain a calcium chloride solution; and the calcium chloride solution is used as a soluble calcium salt solution.
[0014] Optionally, the amount of the hydrochloric acid added is such that the pH of the mixture solution is 4-5.
[0015] The technical solution provided by the present application can include the following beneficial effects: The present application completely avoids the use of toxic barium salt, and the core conversion step utilizes a double decomposition reaction to recover the precipitant calcium ion in the form of calcium carbonate, which can be converted into calcium salt for reuse, realizing the cyclic utilization of calcium element, hardly producing solid waste that is difficult to handle, and conforming to the principle of green chemistry.
[0016] Compared with the traditional "acid dissolution-neutralization" two-step method, the "potassium carbonate conversion" one-step method of the present application directly converts calcium iodate into product potassium iodate, the steps are simple, the operation conditions are mild, and the equipment corrosion and safety risks caused by strong acid treatment are avoided.
[0017] By twice precipitation separation (calcium iodate, calcium carbonate), the impurities such as chloride ions in the original waste liquid are effectively removed. The finally obtained potassium iodate solution has high purity, and after crystallization, it can reach analytical pure or food grade standard. The total recovery rate of iodine can reach more than 94%.
[0018] Through the recovery of calcium carbonate and the recycling of calcium salt, the consumption of fresh calcium salt is reduced. At the same time, the by-product mother liquor (containing potassium chloride) also has recycling value, the overall process cost is low, and the economic benefit is significant.
[0019] It should be understood that the above general description and the following detailed description are only exemplary and explanatory, and cannot limit the present application. BRIEF DESCRIPTION OF DRAWINGS
[0020] The accompanying drawings, which are incorporated into and form part of the specification, illustrate embodiments consistent with the present application and, together with the specification, serve to explain the principles of the present application.
[0021] Figure 1 is a flowchart of a potassium iodate waste liquid recovery treatment method according to an exemplary embodiment. DETAILED DESCRIPTION
[0022] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.
[0023] Figure 1 An embodiment of a potassium iodate waste liquid recovery treatment method of the present application is shown.
[0024] In this alternative embodiment, the potassium iodate waste liquid recovery treatment method comprises the following steps: Step S101, collecting potassium iodate production waste liquid, and clarifying the potassium iodate production waste liquid to obtain a clarified filtrate; Step S102, stirring the obtained clarified filtrate with a pre-configured soluble calcium salt solution to obtain calcium iodate precipitate slurry; Step S103, solid-liquid separation is performed on the obtained calcium iodate precipitate slurry to obtain a calcium iodate filter cake; the obtained calcium iodate filter cake is subjected to stirring reaction with a pre-prepared potassium carbonate solution and water to obtain a reaction mixed solution; Step S104, solid-liquid separation is performed on the obtained reaction mixed solution to obtain a potassium iodate solution; and the obtained potassium iodate solution is subjected to crystallization treatment to obtain potassium iodate.
[0025] In the optional embodiment described above, when the potassium iodate production waste liquid is subjected to clarification treatment to obtain a clarified filtrate, a potassium hydroxide solution can be added to the potassium iodate production waste liquid to adjust the pH of the solution to 9-10; filtration is performed to remove insoluble impurities to obtain the clarified filtrate. The soluble calcium salt solution is a calcium chloride solution. The addition amount of the soluble calcium salt solution is 100%-110% of the theoretical calculation amount. The theoretical calculation amount refers to that, when the potassium iodate content in the potassium iodate waste liquid is 7%, 7 kg of potassium iodate is contained in 100 kg of waste liquid, and the theoretical amount of calcium chloride is calculated according to the following chemical reaction formula: 2KIO3 + CaCl2 = Ca(IO3)2↓ + 2KCl; it is obtained that 16.4 mol of calcium chloride is required, and 2.74 L of calcium chloride solution with a concentration of 6 mol / L is required. That is, the theoretical amount of the calcium chloride solution with a concentration of 6 mol / L is 2.74 L / 100 kg of waste liquid.
[0026] In the optional embodiment described above, when the obtained calcium iodate filter cake is subjected to stirring reaction with a pre-prepared potassium carbonate solution and water to obtain a reaction mixed solution, the obtained calcium iodate filter cake is added to water and subjected to stirring reaction with a potassium carbonate solution until the pH value of the mixed solution is 10-11 to obtain the reaction mixed solution. The reaction temperature when the potassium carbonate solution is added for stirring reaction is 50-90°C, and the reaction time is 30-60 minutes. The addition amount of the potassium carbonate solution is 105%-115% of the theoretical calculation amount. The theoretical calculation amount refers to that the theoretical amount of potassium carbonate is calculated according to the following chemical reaction formula: Ca(IO3)2•6H2O + K2CO3 → CaCO3↓ + 2KIO3; 0.56 kg of 50% potassium carbonate solution is required for 1 kg of calcium iodate, that is, the amount of the 50% potassium carbonate solution is 0.56 kg / kg of barium iodate.
[0027] In the optional embodiment described above, when the obtained potassium iodate solution is subjected to crystallization treatment to obtain potassium iodate, the obtained potassium iodate solution can be subjected to filtration treatment, heating and concentration treatment, cooling and crystallization treatment, suction filtration treatment and drying treatment in sequence to obtain potassium iodate.
[0028] In the optional embodiment, the method for recovering and processing the potassium iodate waste solution further comprises: mixing the calcium carbonate filter cake generated when the reaction mixture solution is obtained with the pre-configured hydrochloric acid to obtain a calcium chloride solution; and using the calcium chloride solution as the soluble calcium salt solution. The amount of the hydrochloric acid added is such that the pH value of the mixed solution is 4-5.
[0029] In order to better understand the above technical solutions of the present application, the above technical solutions of the present application are further described below through specific examples, as follows: Example 1 Take 1 liter of potassium iodate waste solution after production, and analyze the composition thereof as follows: 70 g / L of potassium iodate, 250 g / L of potassium chloride, and 20 g / L of potassium chlorate. The following steps are performed: (1) Pretreatment and pH adjustment: add the waste solution to a 30% potassium hydroxide solution, adjust the pH to 10, and then filter.
[0030] (2) Selective precipitation: slowly add about 29 mL of a calcium chloride solution with a concentration of 6 mol / L (added at 105% of the theoretical amount) to the above solution under stirring, continuously stir at room temperature for 60 minutes, and generate white calcium iodate precipitate.
[0031] (3) Solid-liquid separation: after the reaction is completed, perform suction filtration to obtain a calcium iodate wet filter cake, and wash the filter cake once with a small amount of deionized water. Collect the filtrate (mainly containing KCl and KClO3) for later use.
[0032] (4) Conversion: transfer the calcium iodate filter cake to a beaker, add 500 mL of water, and stir to form a slurry. Under heating at 80°C and stirring, slowly add a 50% potassium carbonate solution (added at 110% of the theoretical amount), control the pH to be about 11, and react for 60 minutes.
[0033] (5) Solid-liquid separation: after the reaction is completed, perform suction filtration while hot to separate out the calcium carbonate precipitate. Wash the calcium carbonate filter cake with a small amount of hot water. Obtain a clear potassium iodate solution.
[0034] (6) Recovery of potassium iodate: transfer the potassium iodate solution to a beaker, heat and concentrate to one-third of the original volume, and then naturally cool and crystallize. Perform suction filtration, and wash the crystals with a small amount of ice water twice. Place the wet crystals in an oven and dry them at 100°C for 4 hours.
[0035] (7) Reuse of calcium carbonate: use the calcium carbonate filter cake obtained in step (5) to form a slurry with an appropriate amount of water, slowly add dilute hydrochloric acid (1:1 dilution) under stirring, adjust the pH to 4.5, and obtain a calcium chloride solution. The solution can be concentrated and reused in step (2).
[0036] After weighing and testing analysis, 51 grams of white crystalline potassium iodate product is obtained, with purity ≥99.5%; the filtrate is collected and tested for potassium iodate content, and it is calculated that the potassium iodate content is about 16 g. Based on the iodine content in the waste liquid, the total recovery rate is 95.7%.
[0037] Example 2 Take 1 liter of waste liquid from the same source as Example 1. The following steps are taken: (1) Pretreatment and pH adjustment: adjust the pH to 9.5 as in Example 1.
[0038] (2) Selective precipitation: the amount of calcium chloride solution added is about 110% of the theoretical amount, and the other operations are the same as in Example 1.
[0039] (3) Solid-liquid separation: same as Example 1.
[0040] (4) Conversion: the reaction temperature is controlled at 90°C, and the amount of potassium carbonate added is 105% of the theoretical amount.
[0041] (5) Solid-liquid separation: same as Example 1.
[0042] (6) Recovery of potassium iodate: same as Example 1.
[0043] (7) Calcium carbonate reuse: same as Example 1, calcium chloride solution is obtained for reuse.
[0044] Finally, about 66 grams of potassium iodate product and filtrate are obtained, with purity ≥99.7%, and the total recovery rate is 94.3%.
[0045] The above examples show that the process of the present application is stable and reliable, realizes internal circulation of materials, and can efficiently, environmentally and economically recover high-quality potassium iodate product from potassium iodate waste liquid.
[0046] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.
Claims
1. A method for recovering and treating potassium iodate waste liquid, characterized in that, include: Collect the potassium iodate production waste liquid and clarify it to obtain a clarified filtrate. The obtained clarified filtrate was stirred and reacted with a pre-prepared soluble calcium salt solution to obtain calcium iodate precipitate slurry; The obtained calcium iodate precipitate slurry was subjected to solid-liquid separation to obtain calcium iodate filter cake; the obtained calcium iodate filter cake was stirred and reacted with a pre-prepared potassium carbonate solution and water to obtain a reaction mixture solution; The obtained reaction mixture was subjected to solid-liquid separation to obtain a potassium iodate solution; and the obtained potassium iodate solution was crystallized to obtain potassium iodate.
2. The method for recovering and treating potassium iodate waste liquid according to claim 1, characterized in that, The potassium iodate production waste liquid is clarified to obtain a clarified filtrate comprising: Add potassium hydroxide solution to the potassium iodate production waste liquid to adjust the pH of the solution to 9-10; filter to remove insoluble impurities and obtain a clear filtrate.
3. The method for recovering and treating potassium iodate waste liquid according to claim 1, characterized in that, The soluble calcium salt solution is a calcium chloride solution.
4. The method for recovering and treating potassium iodate waste liquid according to claim 1, characterized in that, The amount of the soluble calcium salt solution added is 100%-110% of the theoretically calculated amount.
5. The method for recovering and treating potassium iodate waste liquid according to claim 1, characterized in that, The obtained calcium iodate filter cake was stirred and reacted with a pre-prepared potassium carbonate solution and water to obtain a reaction mixture comprising: The obtained calcium iodate filter cake was added to water, and potassium carbonate solution was added and stirred until the pH of the mixed solution reached 10-11, thus obtaining the reaction mixture.
6. The method for recovering and treating potassium iodate waste liquid according to claim 5, characterized in that, When adding potassium carbonate solution and stirring, the reaction temperature should be 50-90℃ and the reaction time should be 30-60 minutes.
7. The method for recovering and treating potassium iodate waste liquid according to claim 1, characterized in that, The amount of potassium carbonate solution added is 105%-115% of the theoretically calculated amount.
8. The method for recovering and treating potassium iodate waste liquid according to claim 1, characterized in that, The obtained potassium iodate solution was subjected to crystallization treatment to obtain potassium iodate, which includes: The obtained potassium iodate solution was subjected to sequential filtration, heating and concentration, cooling and crystallization, vacuum filtration and drying to obtain potassium iodate.
9. The method for recovering and treating potassium iodate waste liquid according to claim 1, characterized in that, Also includes: The calcium carbonate filter cake produced when the reaction mixture is obtained is mixed with pre-prepared hydrochloric acid to obtain a calcium chloride solution. And calcium chloride solution was used as a soluble calcium salt solution.
10. The method for recovering and treating potassium iodate waste liquid according to claim 9, characterized in that, The amount of hydrochloric acid added is such that the pH of the mixed solution is 4-5.