Production system and method of calcium iodate

Abstract

The invention discloses a production system and method of calcium iodate, and belongs to the technical field of chemical synthesis and separation. The production system of the calcium iodate comprises a reaction kettle, a stirrer, a neutralization tank, a synthesis tank, a filter, a dryer and a crusher. The production method of the calcium iodate comprises the following steps: 1, producing potassium hydrogen iodate from potassium chlorate and iodine, 2, neutralizing the potassium hydrogen iodate with potassium hydroxide to produce potassium iodate, 3, reacting the potassium iodate with calcium chloride to produce a calcium iodate suspension, and finally, filtering and drying to obtain potassium iodate monohydrate. According to the method, a chlorine oxidation method, a hydrogen peroxide oxidation method and an electrochemical oxidation method are not needed, the second step and the third step can be carried out under normal pressure without heating except for heating for producing the potassium hydrogen iodate, and special equipment is not needed. No three wastes are discharged in the whole production process, and meanwhile, a byproduct potassium chloride can be produced.

Description

Technical Field

[0001] This invention relates to a production system and method for calcium iodate, belonging to the field of chemical synthesis and separation technology. Background Technology

[0002] Iodine is a component of the thyroid gland, and thyroxine is an essential bioactive substance for animal growth and reproduction. Potassium iodide is a commonly added iodine source in feed, which is readily available, easily soluble in water, and readily absorbed by animals. However, it has poor stability: it is prone to deliquescence and clumping, and is easily oxidized upon prolonged exposure to air, releasing iodine. It also decomposes when mixed with trace elements such as copper salts and selenites. Therefore, feed premixes made with potassium iodide and other minerals experience an iodine loss rate of over 70% after 4 months of storage, and over 50% within 1 to 8 weeks under moist or damp conditions. The released iodine poses a threat to vitamins, antibiotics, and other medications.

[0003] Calcium iodate exists in three forms: anhydrous calcium iodate (chemical formula Ca(IO3)2), calcium iodate monohydrate (chemical formula Ca(IO3)2·H2O), and calcium iodate hexahydrate (chemical formula Ca(IO3)2·6H2O). All are white crystalline powders, odorless and tasteless. Calcium iodate monohydrate (Ca(IO3)2·H2O) is the most commonly used. Calcium iodate monohydrate is slightly soluble in water but insoluble in alcohol. It is an excellent source of iodine in food and feed, exhibiting good chemical stability. It is more stable than iodides in food, and its biological value is similar to that of potassium iodide. It does not show any changes when mixed with various trace elements. Calcium iodate can be used as an iodine source for the trace element iodine in various animal feeds, which can improve the egg production rate of laying hens and the milk production of dairy cows; it can be used as an iodine source in the production of feed premixes, for the cultivation of high-iodine eggs for health care, and can prevent and treat hyperlipidemia, diabetes, and high cholesterol. It also has significant effects on the prevention and treatment of vesicular eczema and anti-cancer; it can also be used for the iodization of table salt.

[0004] Currently, the main methods for preparing calcium iodate are as follows: 1. Chlorine Oxidation Method: Using chlorine and iodine as raw materials, chlorine is passed into a boiling solution containing iodine, where the iodine is oxidized to iodic acid. The iodine is then neutralized with lime milk, and the precipitate is separated, washed, and dried to obtain calcium iodate. Calcium chloride solution is produced as a byproduct. This method uses chlorine, which is highly toxic, corrosive, and an oxidizing agent, and can easily cause unexpected harm to humans and the environment.

[0005] 2. Hydrogen peroxide oxidation method: Using hydrogen peroxide and iodine as raw materials, in the presence of nitric acid and a catalyst, iodine is oxidized to iodic acid. After neutralization with lime milk, the precipitate is separated, washed, and dried to obtain calcium iodate. Calcium chloride solution and nitrogen oxides are produced as byproducts. This method uses hydrogen peroxide, which is not only a hazardous chemical but also a precursor to explosives, and its transportation and use are subject to numerous restrictions.

[0006] 3. Electrochemical oxidation method: Industrial refined iodine is first dissolved in potassium hydroxide solution, then potassium iodate is prepared by electrolytic oxidation in an electrolytic cell. Potassium iodate is then reacted with calcium chloride to obtain calcium iodate, with potassium chloride solution and hydrogen gas as byproducts. This method requires a specially designed electrolytic cell with an ion-exchange membrane, is complex, and the produced hydrogen gas can easily cause fires and explosions.

[0007] In view of the above problems, there is an urgent need to provide a new calcium iodate production system and method to obtain qualified calcium iodate products without using chlorine, hydrogen peroxide and complex electrolytic cells. Summary of the Invention

[0008] The purpose of this invention is to provide a calcium iodate production system and method to solve the problems of existing calcium iodate preparation methods being environmentally harmful, having complex processes, and posing safety risks.

[0009] The calcium iodate production system of the present invention adopts the following technical solution: A calcium iodate production system includes a reaction vessel, a neutralization tank, a synthesis tank, a filter, a dryer, and a pulverizer connected in sequence. The reaction vessel has an iodine inlet and a potassium chlorate inlet at the top, and a potassium hydrogen iodate outlet at the bottom. The neutralization tank has a potassium hydrogen iodate inlet and a potassium hydroxide inlet at the top, the potassium hydrogen iodate inlet being connected to the potassium hydrogen iodate outlet via a pipe, and a potassium iodate outlet at the bottom. The synthesis tank has a potassium iodate inlet and a calcium chloride inlet at the top, the potassium iodate inlet being connected to the potassium iodate outlet via a pipe, and a calcium iodate outlet at the bottom. The filter has a turbid liquid inlet and a solid outlet at the top, the turbid liquid inlet being connected to the calcium iodate outlet via a pipe, and a filtrate outlet at the bottom. The dryer's inlet is connected to the filter's solid outlet, the dryer's outlet is connected to the pulverizer's inlet, and the pulverizer's outlet is the target product outlet.

[0010] The reactor, neutralization tank, and synthesis tank are all equipped with a stirrer.

[0011] The outer wall of the reactor is equipped with a heating jacket; the outer wall of the neutralization tank is provided with a heat insulation layer.

[0012] The filter is a sealed centrifugal filter; the dryer is a vacuum dryer.

[0013] The method for producing calcium iodate of the present invention adopts the following technical solution: A method for producing calcium iodate, comprising the following steps: (1) Production of potassium hydrogen iodate: Water is added to the reaction vessel and potassium chlorate is added under heating and stirring. After the potassium chlorate is completely dissolved, fine iodine particles are added. The molar ratio of potassium chlorate to iodine is 11~12:6. The solution temperature is kept ≤90℃ until the reaction is completed. The produced potassium hydrogen iodate solution is discharged from the potassium hydrogen iodate outlet at the bottom of the reaction vessel to the neutralization tank; (2) Production of potassium iodate: The potassium hydrogen iodate solution from the reaction vessel enters the neutralization tank from the potassium hydrogen iodate inlet at the top. The solution temperature is kept ≥60℃ under stirring. Potassium hydroxide is added to dissolve and neutralize. The pH value is adjusted to ≤9. The molar ratio of potassium hydrogen iodate to potassium hydroxide is 10: 10~11, potassium hydrogen iodate in the solution is completely converted into potassium iodate, and the produced potassium iodate solution is sent to the synthesis tank from the potassium iodate outlet at the bottom of the neutralization tank; (3) Production of calcium iodate: the potassium iodate solution from the neutralization tank enters the synthesis tank from the potassium iodate inlet at the top, and the solution temperature is kept ≤70℃ while stirring. Calcium chloride is added to dissolve and neutralize, and the pH value is adjusted to ≥6. The molar ratio of potassium iodate to calcium chloride is 20: 10~11, potassium iodate in the solution is completely converted into calcium iodate precipitate. The calcium iodate suspension produced enters the filter from the calcium iodate outlet at the bottom of the synthesis tank; (4) Filtration: the calcium iodate suspension enters the filter for filtration. The filtrate is discharged from the filtrate outlet at the bottom of the filter and goes to the potassium chloride recovery system through the potassium chloride solution conveying pipeline. After filtration, calcium iodate suspension is obtained as calcium iodate hexahydrate solid. The calcium iodate hexahydrate solid enters the dryer from the solid outlet of the filter; (5) Drying and pulverizing: the calcium iodate hexahydrate solid is dried in the dryer at a drying temperature ≤160℃. After drying, the calcium iodate solid exiting the dryer is calcium iodate monohydrate. It enters the pulverizer from the pulverizer inlet for pulverizing and is used as the target product - calcium iodate Ca(IO3)2·H2O to the boundary area.

[0014] The drying temperature range in the dryer is 100℃~160℃, and the mass concentration of calcium iodate Ca(IO3)2·H2O in the target product is ≥99%.

[0015] The proportion of calcium iodate with a particle size ≤180μm after being pulverized by a pulverizer is ≥95%.

[0016] In step (1), the temperature of the solution in the reactor is 70℃~90℃, and the reaction time is 10~30 minutes.

[0017] In step (2), the temperature of the solution in the neutralization tank is 60℃~80℃, the pH value of the solution after neutralization is adjusted to 8~9, and the neutralization time is 20~40 minutes.

[0018] In step (3), the temperature of the solution in the synthesis tank is room temperature to 70°C, the pH value of the neutralized solution is adjusted to 6 to 7, and the synthesis time is 20 to 40 minutes.

[0019] The beneficial effects of this invention are as follows: The first step involves producing potassium hydrogen iodate from potassium chlorate and iodine; the second step involves neutralizing potassium hydrogen iodate with potassium hydroxide to produce potassium iodate; the third step involves reacting potassium iodate with calcium chloride to produce a calcium iodate suspension; and finally, after filtration and drying, the product—calcium iodate monohydrate—is obtained. This invention does not use chlorine oxidation, hydrogen peroxide oxidation, or electrochemical oxidation. The entire production process produces no waste and generates potassium chloride as a byproduct. Except for the appropriate heating required for the production of potassium hydrogen iodate, the production of both potassium iodate and calcium iodate can be carried out without heating at normal pressure, without the need for special equipment. This invention is environmentally friendly, has a simple process, and is unlikely to pose safety risks. This invention overcomes the drawbacks of using chlorine to oxidize iodine to produce iodic acid, which is harmful to human health and the environment; it also overcomes the drawbacks of using hydrogen peroxide and iodine to produce calcium iodate, which is prone to explosion and has limited transportation and use; and it also overcomes the drawbacks of using electrochemical oxidation to produce iodic acid, which is complex and unsafe.

[0020] Preferably, the drying temperature range of the dryer is 100℃~160℃. The target product, calcium iodate (Ca(IO3)2·H2O), contains one molecule of water of crystallization, thus avoiding excessively high temperatures that would waste energy and cause the calcium iodate to decompose.

[0021] Preferably, a sealed centrifugal filter is used for the filter and a vacuum dryer is used for the dryer, which improves the quality of the target product and ensures that the final product quality meets chemical standards. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of a calcium iodate production system according to an embodiment of the present invention.

[0023] In the diagram: 1-Reaction vessel, 2-Agitator, 3-Neutralization tank, 4-Synthesis tank, 5-Filter, 6-Dryer, 7-Pulverizer. Detailed Implementation

[0024] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. Examples of the following embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. Based on the following embodiments, all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this patent.

[0025] like Figure 1As shown, an embodiment of the present invention provides a calcium iodate production system comprising a reaction vessel 1, a neutralization tank 3, a synthesis tank 4, a filter 5, a dryer 6, and a pulverizer 7 connected in sequence. The reaction vessel 1 has an iodine inlet and a potassium chlorate inlet at its top, and a potassium hydrogen iodate outlet at its bottom. The neutralization tank 3 has a potassium hydrogen iodate inlet and a potassium hydroxide inlet at its top, with the potassium hydrogen iodate inlet connected to the potassium hydrogen iodate outlet of the reaction vessel 1 via a pipe, and a potassium iodate outlet at its bottom. The synthesis tank 4 has a potassium iodate inlet and a calcium chloride inlet at its top, with the potassium iodate inlet connected to the potassium iodate outlet of the neutralization tank 3 via a pipe, and a calcium iodate outlet at its bottom. The filter 5 has a turbid liquid inlet and a solid outlet at its top, with the turbid liquid inlet connected to the calcium iodate outlet of the synthesis tank 4 via a pipe, and a filtrate outlet at its bottom. The dryer 6 has its inlet connected to the solid outlet of the filter 5, and its outlet connected to the inlet of the pulverizer 7. The outlet of the pulverizer 7 is the target product outlet.

[0026] The reactor 1, neutralization tank 3, and synthesis tank 4 are all equipped with stirrers 2. The outer wall of the reactor 1 is equipped with a heating jacket; the outer wall of the neutralization tank 3 is equipped with a heat insulation layer. The filter 5 is a sealed centrifugal filter; the dryer 6 is a vacuum dryer.

[0027] An embodiment of the present invention provides a method for producing calcium iodate, comprising the following steps: (1) Production of potassium hydrogen iodate: Water is added to a reaction vessel, and potassium chlorate is added under heating and stirring. After the potassium chlorate is completely dissolved, fine iodine particles (particle size of 1-100 micrometers) are added. The molar ratio of potassium chlorate to iodine is 11:6. The solution temperature is maintained at 80°C until the reaction is complete. The reaction time is 20 minutes. The produced potassium hydrogen iodate solution is discharged from the potassium hydrogen iodate outlet at the bottom of the reaction vessel to a neutralization tank. In other embodiments, the molar ratio of potassium chlorate to iodine can be 11-12:6, the temperature of the solution in the reaction vessel is ≤90°C, preferably 70°C-90°C, and the reaction time is 10-30 minutes.

[0028] (2) Production of potassium iodate: Potassium hydrogen iodate solution from the reactor enters the neutralization tank through the potassium hydrogen iodate inlet at the top. The solution temperature is maintained at 70°C with stirring. Potassium hydroxide is added to dissolve and neutralize the solution. The molar ratio of potassium hydrogen iodate to potassium hydroxide is 1:1. The neutralization time is 30 minutes, and the pH is adjusted to 8.5. The potassium hydrogen iodate in the solution is completely converted to potassium iodate. The produced potassium iodate solution is discharged from the potassium iodate outlet at the bottom of the neutralization tank to the synthesis tank. In other embodiments, the temperature of the solution in the neutralization tank is greater than 60°C, typically 60°C to 80°C. The pH of the neutralized solution is ≤9, typically adjusted to 8 to 9. The molar ratio of potassium hydrogen iodate to potassium hydroxide is 10:10 to 11, and the neutralization time is 20 to 40 minutes.

[0029] (3) Production of calcium iodate: Potassium iodate solution from the neutralization tank enters the synthesis tank through the potassium iodate inlet at the top. The solution temperature is maintained at 60°C with stirring. Calcium chloride is added to dissolve and neutralize the solution. The molar ratio of potassium iodate to calcium chloride is 2:1. The pH is adjusted to 6.8. The potassium iodate in the solution completely precipitates into calcium iodate. The synthesis time is 30 minutes. The produced calcium iodate suspension enters the filter through the calcium iodate outlet at the bottom of the synthesis tank. In other embodiments, the molar ratio of potassium iodate to calcium chloride can be 20:10~11, the temperature of the solution in the synthesis tank is ≤70°C (usually room temperature to 70°C), the pH of the solution after neutralization with calcium chloride is ≥6 (usually adjusted to 6~7), and the synthesis time is 20~40 minutes.

[0030] (4) Filtration: The calcium iodate suspension enters the filter and is filtered. The filtrate is discharged from the filtrate outlet at the bottom of the filter and goes to the potassium chloride recovery system through the potassium chloride solution conveying pipeline. After filtration, the calcium iodate suspension yields calcium iodate hexahydrate solid. The calcium iodate hexahydrate solid enters the dryer from the solid outlet of the filter.

[0031] (5) Drying and pulverizing: Calcium iodate hexahydrate solid is dried in a dryer at a temperature of 140℃ (which can be set to ≤160℃ as needed; the drying temperature range is usually 100℃~160℃). After drying, the calcium iodate solid exiting the dryer is calcium iodate monohydrate, which enters the pulverizer inlet for pulverization, serving as the target product—calcium iodate Ca(IO3)2·H2O. The proportion of calcium iodate with a particle size ≤180μm after pulverization is ≥95%, and the mass concentration of calcium iodate Ca(IO3)2·H2O in the target product is ≥99%.

[0032] The first step of this invention is to produce potassium hydrogen iodate using potassium chlorate and iodine; the second step is to produce potassium iodate using potassium hydrogen iodate and potassium hydroxide; the third step is to produce calcium iodate suspension using potassium iodate and calcium chloride; and finally, the product—calcium iodate monohydrate—is obtained through filtration and drying. This invention does not use chlorine oxidation, hydrogen peroxide oxidation, or electrochemical oxidation. Except for the heating required for the production of potassium hydrogen iodate, the second and third steps can be carried out without heating under normal pressure and without special equipment. The entire production process generates no waste, protecting the environment. The evaluation results of an example of calcium iodate production using the above embodiments are shown in Table 1.

[0033] Table 1 Performance Evaluation Results of a 1000 kg / day Calcium Iodate Production System

Claims

1. A system for producing calcium iodate, characterized by: It includes the reaction kettle, neutralization tank, synthesis tank, filter, dryer, pulverizer connected in turn, the top of the reaction kettle is equipped with raw material iodine inlet and raw material potassium chlorate inlet, the bottom of the reaction kettle is equipped with potassium hydrogen iodate outlet; The top of the neutralization tank is equipped with potassium hydrogen iodate inlet and potassium hydroxide raw material inlet, the potassium hydrogen iodate inlet is connected with the potassium hydrogen iodate outlet through pipeline, the bottom of the neutralization tank is equipped with potassium iodate outlet; The top of the synthesis tank is equipped with potassium iodate inlet and raw material calcium chloride inlet, the potassium iodate inlet is connected with the potassium iodate outlet through pipeline, the bottom of the synthesis tank is equipped with calcium iodate outlet; The top of the filter is equipped with turbidity inlet and solid outlet, the turbidity inlet is connected with the calcium iodate outlet through pipeline, the bottom of the filter is equipped with filtrate outlet; The inlet of the dryer is connected with the solid outlet of the filter, the outlet of the dryer is connected with the inlet of the pulverizer, and the outlet of the pulverizer is the target product outlet.

2. The calcium iodate production system according to claim 1, characterized by: The inside of the reaction kettle, the neutralization tank and the synthesis tank is equipped with a stirrer.

3. The calcium iodate production system according to claim 1, characterized by: The outer wall of the reaction kettle is provided with a heating jacket; The outer wall of the neutralization tank is provided with a heat preservation layer.

4. The calcium iodate production system according to claim 1, characterized by: The filter adopts a sealed centrifugal filter, and the dryer adopts a vacuum dryer.

5. A method for producing calcium iodate, characterized by, It includes the following steps: (1) Production of potassium hydrogen iodate: water is added to the reaction kettle, and potassium chlorate is added under heating and stirring, after the potassium chlorate is completely dissolved, fine particle iodine is added, the molar ratio of potassium chlorate to iodine is 11-12:6, the solution temperature is kept ≤90℃ until the reaction is completed, and the produced potassium hydrogen iodate solution is discharged from the potassium hydrogen iodate outlet at the bottom of the reaction kettle to the neutralization tank; (2) Production of potassium iodate: the potassium hydrogen iodate solution from the reaction kettle is introduced into the neutralization tank from the top potassium hydrogen iodate inlet, the solution temperature is kept ≥60℃ under stirring, potassium hydroxide is added to dissolve and neutralize, the pH value is adjusted to ≤9, the molar ratio of potassium hydrogen iodate to potassium hydroxide is 10:10-11, the potassium hydrogen iodate in the solution is completely converted into potassium iodate, and the produced potassium iodate solution is discharged from the potassium iodate outlet at the bottom of the neutralization tank to the synthesis tank; (3) Production of calcium iodate: the potassium iodate solution from the neutralization tank is introduced into the synthesis tank from the top potassium iodate inlet, the solution temperature is kept ≤70℃ under stirring, calcium chloride is added to dissolve and neutralize, the pH value is adjusted to ≥6, the molar ratio of potassium iodate to calcium chloride is 20:10-11, the potassium iodate in the solution is completely converted into calcium iodate precipitate, and the produced calcium iodate suspension is introduced into the filter from the calcium iodate outlet at the bottom of the synthesis tank; (4) Filtration: the calcium iodate suspension is introduced into the filter to be filtered, the filtrate is discharged from the filtrate outlet at the bottom of the filter, and is transported to the potassium chloride recovery system through the potassium chloride solution pipeline, and the calcium iodate suspension is filtered to obtain calcium iodate hexahydrate solid, which is introduced into the dryer from the solid outlet of the filter; (5) Drying and pulverization: the calcium iodate hexahydrate solid is dried in the dryer, the drying temperature is ≤160℃, after the drying is completed, the calcium iodate solid discharged from the dryer is calcium iodate monohydrate, which is introduced into the pulverizer from the inlet of the pulverizer to be pulverized, and is taken out as the target product, calcium iodate Ca(IO3)2·H2O.

6. The method for producing calcium iodate according to claim 5, characterized by: The drying temperature in the dryer ranges from 100 DEG C to 160 DEG C, and the mass concentration of calcium iodate Ca(IO3)2·H2O in the target product is greater than or equal to 99%.

7. The method of producing calcium iodate according to claim 5, characterized by: The proportion of calcium iodate with a particle size of less than or equal to 180 microns after being crushed by the crusher is greater than or equal to 95%.

8. The method of producing calcium iodate according to claim 1, characterized by: In step (1), the temperature of the solution in the reaction kettle is 70 DEG C to 90 DEG C, and the reaction time is 10 to 30 minutes.

9. The method of producing calcium iodate according to claim 1, characterized by: In step (2), the temperature of the solution in the neutralization tank is 60 DEG C to 80 DEG C, the pH value of the solution after neutralization is adjusted to 8 to 9, and the neutralization time is 20 to 40 minutes.

10. The method of producing calcium iodate according to claim 1, characterized by: In step (3), the temperature of the solution in the synthesis tank is normal temperature to 70 DEG C, the pH value of the solution after neutralization is adjusted to 6 to 7, and the synthesis time is 20 to 40 minutes.

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