A method for recycling iodine catalyst in the production of low-arsenic and low-antimony yellow phosphorus

Abstract

This invention discloses a method for recycling iodine catalyst in the production of low-arsenic and low-antimony yellow phosphorus, comprising the following steps: S1, mixing a solution; S2, mixing and stirring the mixed solution with liquefied yellow phosphorus and iodine catalyst to obtain an aqueous phase of the reaction solution and an iodine-containing yellow phosphorus phase; S3, allowing the solution to stand and separate into layers to obtain deiodized yellow phosphorus and an aqueous washing solution; S4, combining the aqueous washing solution with the aqueous phase of the reaction solution to obtain an iodine-containing aqueous phase, wherein the iodine-containing aqueous phase replaces the iodine catalyst used in subsequent S2 and participates in the subsequent S2-S4 steps of the cycle. This invention can effectively recover and recycle iodine catalyst, reducing the consumption of iodine catalyst and achieving the goal of saving resources. Its overall iodine recovery rate can reach over 80%, and the iodine consumption in the yellow phosphorus purification process is reduced from 0.01-0.1% of the yellow phosphorus mass to 0.2-2.0 ppm, which has significant practical value.

Description

Technical Field

[0001] This invention relates to the field of catalyst technology, and in particular to a method for recycling iodine catalysts in the production of low-arsenic, low-antimony yellow phosphorus. Background Technology

[0002] Yellow phosphorus is an important phosphorus chemical raw material, especially high-purity phosphorus chemical products. High-purity yellow phosphorus is mainly used in the production of food-grade and pharmaceutical-grade phosphates, electronic-grade phosphorus derivatives, or electronic-grade phosphoric acid. It is widely used in the production of food additives, pharmaceuticals, microelectronic integrated circuit etching and cleaning agents, high-grade lubricant additives, and semiconductor diffusion additives. These applications impose strict requirements on the impurity content of yellow phosphorus, with arsenic and antimony content required to be less than 20 ppm, or even lower.

[0003] Although my country has the world's largest industrial production capacity of yellow phosphorus, the quality of yellow phosphorus products is not graded. The main impurities are organic matter, arsenic, and iron, followed by antimony, zinc, copper, nickel, and lead. The total content of other impurities is in the range of 10⁻⁹. Among these, the organic matter is mainly polynuclear aromatic hydrocarbons, which have a strong affinity for yellow phosphorus. Arsenic mainly exists in the form of arsenic phosphide and readily forms eutectic with phosphorus. Although antimony, phosphorus, and arsenic belong to the same group of elements, they are in different periods. Arsenic has stronger interlayer covalent properties and greater interlayer distance than antimony, resulting in stronger metallic properties in antimony. Under acidic conditions, arsenic is more easily oxidized than antimony. Antimony and phosphorus are tightly bound, making it impossible to separate them solely through water extraction or filtration; it is one of the more difficult metals to remove.

[0004] In industrial yellow phosphorus, the arsenic content is generally between 100-300 ppm, and the antimony content is also generally between 100-300 ppm. Furthermore, with the depletion of phosphate rock, the arsenic and antimony contents in industrial yellow phosphorus tend to gradually increase, significantly impacting its quality. Since arsenic and antimony belong to the same group as phosphorus and share many similar physicochemical properties, during the electric furnace phosphorus production process, arsenic and antimony are reduced simultaneously with phosphorus. These arsenic and antimony are condensed together in the yellow phosphorus product, making the separation of yellow phosphorus from arsenic and antimony difficult.

[0005] There are chemical and physical methods for purifying yellow phosphorus. Physical methods mainly include vacuum distillation, activated carbon adsorption, electromagnetic purification, extraction purification, zone melting, and microfiltration purification. However, the phosphorus yield of physical purification methods is generally low, typically only 60-80%, and not exceeding 90%. Chemical methods mainly target single impurities in yellow phosphorus. Wan Ronghui et al., in patent CN101327917, mixed yellow phosphorus with a 10%-12% (mass fraction) nitric acid solution, used sodium bromate as an oxidizing enhancer, and stirred the reaction at 70°C. Arsenic was oxidized and hydrated into arsenous acid or arsenic acid, which entered the aqueous phase. After 3 hours, the dearsenic-removed yellow phosphorus was removed, with an arsenic removal rate ≥96% and a phosphorus yield ≥92%. Lin Jun et al., in a method for removing antimony from yellow phosphorus (CN103771365A), described a method that involves thoroughly mixing an oxidizing antimony-removing agent (5-30% nitric acid solution) with molten yellow phosphorus in a ratio of 1:1 to 5, reacting and immersing at 60-80℃ for 10-60 minutes. This allows the antimony in the yellow phosphorus to enter the liquid phase, separating the phosphorus phase from the liquid phase, thus achieving the purpose of antimony removal. All of the above methods are carried out in an acidic environment of nitric acid, introducing nitrate ions, which affects the stability of product quality. Furthermore, the purification process involves high reaction temperatures and vigorous reactions. CN112875661A discloses a method for producing electronic-grade yellow phosphorus, using oxidants such as polyphosphoric acid and hydrogen peroxide under a protective atmosphere to purify yellow phosphorus, obtaining high-purity electronic-grade yellow phosphorus. However, its effectiveness in removing arsenic and antimony is unknown. Patent CN202310241160.4 discloses a method for simultaneously removing arsenic and antimony from yellow phosphorus. The method involves thoroughly mixing heated liquefied yellow phosphorus with a certain concentration of hydrogen peroxide-based oxidant in a reaction vessel under hot water sealing conditions. A dispersant, acidifying agent, and iodide catalyst are added, and the mixture is stirred at 55–65°C. This allows arsenic and antimony impurities in the yellow phosphorus to react and enter the aqueous phase. After washing and settling for phase separation, high-purity yellow phosphorus with low arsenic and antimony content is obtained. However, while this method yields a low-arsenic and low-antimony yellow phosphorus product, the added iodide catalyst, under these reaction conditions, causes iodine to exist as elemental iodine in the product yellow phosphorus, not only reducing the product quality but also wasting valuable iodine resources.

[0006] In summary, existing technologies typically target the removal of arsenic and antimony from yellow phosphorus, but there are virtually no reports on the newly introduced iodine element during the yellow phosphorus purification process and its recycling. Therefore, there is an urgent need to develop a technology for recycling iodine during the yellow phosphorus purification process, which should not only improve product quality but also effectively recycle the scarce resource of iodine. Summary of the Invention

[0007] This invention provides a method for recycling iodine catalyst in the production of low-arsenic and low-antimony yellow phosphorus. The method is simple and convenient to operate, can effectively remove arsenic and antimony from yellow phosphorus to obtain high-quality yellow phosphorus products, and can also efficiently recover iodine catalyst, thereby saving resources.

[0008] The solution of the present invention is:

[0009] A method for recycling iodine catalyst in the production of low-arsenic and low-antimony yellow phosphorus includes the following steps:

[0010] S1. Mix the aqueous solution of the oxidant with the acidifier and dispersant to obtain a mixed solution;

[0011] S2. The mixed solution is mixed and stirred with liquefied yellow phosphorus and iodine catalyst, and then allowed to stand to obtain an aqueous phase and an iodine-containing yellow phosphorus phase of the reaction solution.

[0012] S3. Under ultrasonic and stirring conditions, water is mixed with the iodine-containing yellow phosphorus phase for washing, and the mixture is allowed to stand and separate into layers to obtain deiodized yellow phosphorus and aqueous washing solution.

[0013] S4. Combine the aqueous washing solution with the aqueous reaction solution to obtain an iodine-containing aqueous phase. Replace the iodine catalyst and mixed solution in S2 with the iodine-containing aqueous phase. Calculate the loss based on the content of iodine catalyst, oxidant, acidifier, and dispersant in the iodine-containing aqueous phase, replenish it, and add it to step S2 to participate in the subsequent S2-S4 cycle.

[0014] As a preferred technical solution, the iodine catalyst in S2 is at least one of elemental iodine, hydroiodic acid, and sodium iodide.

[0015] As a preferred technical solution, the iodine catalyst in S2 is a mixture of iodine agent and sodium iodide; the content of sodium iodide in the iodine catalyst is 10wt% to 30wt%; and the iodine agent is at least one of elemental iodine or hydroiodic acid.

[0016] As a preferred technical solution, the amount of iodine catalyst added in S2 is 0.01 to 0.1 wt% of the yellow phosphorus.

[0017] As a preferred technical solution, the ultrasonic frequency in S3 is 30-100kHz, and the linear velocity of stirring is 0.2-2m / s.

[0018] As a preferred technical solution, the oxidant is hydrogen peroxide, and the amount of the oxidant is 3 to 7 times the mass of the yellow phosphorus; the concentration of the aqueous solution of the oxidant is 5 to 15 wt%.

[0019] As a preferred technical solution, the acidifying agent is at least one of phosphoric acid and polyphosphoric acid; the amount of the acidifying agent is 0.1 to 1 wt% of the oxidizing agent.

[0020] As a preferred technical solution, the dispersant is at least one of hexadecyltrimethylammonium bromide, sodium lignosulfonate, and polyethylene glycol; the amount of the dispersant is 0.05 to 0.1 wt% of the oxidant.

[0021] As a preferred technical solution, the temperature of the liquefied yellow phosphorus in S2 is 50-70°C, the reaction temperature of the yellow phosphorus with the mixed solution and the iodine catalyst is 55-65°C, and the reaction time is 1-3 hours.

[0022] As a preferred technical solution, in step S3, the iodine-containing yellow phosphorus phase is mixed with pure water at 60-80°C and then washed with water at 55-70°C.

[0023] A method for recycling iodine catalyst in the production of low-arsenic and low-antimony yellow phosphorus using the above-mentioned technical solution includes the following steps: S1, mixing an aqueous solution of oxidant with an acidifying agent and a dispersant to obtain a mixed solution; S2, mixing and stirring the mixed solution with liquefied yellow phosphorus and iodine catalyst, and allowing it to stand to obtain an aqueous phase of the reaction solution and an iodine-containing yellow phosphorus phase; S3, washing the iodine-containing yellow phosphorus phase with water under ultrasonic and stirring conditions, and allowing it to stand to separate into layers to obtain deiodized yellow phosphorus and an aqueous washing solution; S4, combining the aqueous washing solution with the aqueous phase of the reaction solution to obtain an iodine-containing aqueous phase, replacing the iodine catalyst and mixed solution in S2 with the iodine-containing aqueous phase, calculating the loss based on the content of iodine catalyst, oxidant, acidifying agent, and dispersant in the iodine-containing aqueous phase, replenishing it, and adding it to step S2 to participate in the subsequent S2-S4 steps of the cycle.

[0024] Advantages of this invention:

[0025] 1. After the oxidant, acidifier, dispersant, yellow phosphorus, and iodine catalyst are mixed and reacted, the aqueous phase of the reaction solution is separated from the iodine-containing yellow phosphorus. The iodine-containing yellow phosphorus is then washed with water under ultrasonic stirring to further dissolve the iodine in the aqueous phase for recovery. The recovered aqueous washing solution is then recovered together with the aqueous reaction solution of the mixed solution. Based on the reaction loss, some oxidant, acidifier, dispersant, and iodine catalyst are added to continue purifying the yellow phosphorus.

[0026] 2. This invention utilizes an iodine catalyst to remove arsenic and antimony from yellow phosphorus, improving the quality of the yellow phosphorus. Simultaneously, it effectively recovers and recycles the iodine catalyst, reducing its consumption and conserving resources. The overall iodine recovery rate can reach over 80%, and the iodine consumption in the yellow phosphorus purification process is reduced from 0.01–0.1% of the yellow phosphorus mass to 0.2–2.0 ppm, demonstrating significant practical value. Detailed Implementation

[0027] This invention provides a method for recycling iodine catalysts in the production of low-arsenic and low-antimony yellow phosphorus.

[0028] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below with reference to specific embodiments.

[0029] Example 1

[0030] A method for recycling iodine catalyst in the production of low-arsenic and low-antimony yellow phosphorus includes the following steps:

[0031] S1. Mix the aqueous solution of the oxidant with the acidifier and dispersant, and preheat to 65°C to obtain a mixed solution;

[0032] S2. Preheat the yellow phosphorus to 70°C to fully liquefy it, and mix it with the mixed solution in step S1 and the iodine catalyst. Stir the mixture at 65°C for 1 hour, then let it stand for 30 minutes. After separation, the aqueous phase of the reaction solution and the iodine-containing yellow phosphorus phase are obtained.

[0033] S3. Under 100kHz ultrasound and 2m / s stirring speed, 80℃ pure water is mixed with the iodine-containing yellow phosphorus phase from step S2 for washing. After standing and separating into layers, deiodized yellow phosphorus and aqueous washing solution are obtained. Deiodized yellow phosphorus is washed with 70℃ hot water until the washing water is neutral to obtain low arsenic and low antimony yellow phosphorus.

[0034] S4. Combine the aqueous washing solution from step S3 and the aqueous reaction solution from step S2 to obtain an iodine-containing aqueous phase. Calculate the loss based on the content of iodine catalyst, oxidant, acidifier, and dispersant in the iodine-containing aqueous phase, replenish it, and add it to step S2. Replace the iodine catalyst and mixed solution with the iodine-containing aqueous phase in step S2, and repeat steps S2 to S4 to achieve the recycling of the iodine catalyst.

[0035] The iodine catalyst is elemental iodine, and its amount is 0.1 wt% of yellow phosphorus.

[0036] The oxidant is hydrogen peroxide, and its dosage is 7 times the mass of yellow phosphorus; the aqueous solution concentration of the oxidant is 5 wt%.

[0037] The acidifying agent is phosphoric acid, and the amount of acidifying agent used is 1 wt% of hydrogen peroxide, while the concentration of phosphoric acid is 85 wt%.

[0038] The dispersant is hexadecyltrimethylammonium bromide; the amount of dispersant used is 0.1 wt% of hydrogen peroxide.

[0039] At the end of each cycle, the loss is calculated based on the content of iodine catalyst, oxidant, acidifier, and dispersant in the iodine-containing aqueous phase, and timely replenishment is made in the next cycle.

[0040] Example 2

[0041] A method for recycling iodine catalyst in the production of low-arsenic and low-antimony yellow phosphorus includes the following steps:

[0042] S1. Mix the aqueous solution of the oxidant with the acidifier and dispersant, and preheat to 55°C to obtain a mixed solution;

[0043] S2. Preheat the yellow phosphorus to 50°C to fully liquefy it, and mix it with the mixed solution in step S1 and the iodine catalyst. Stir the mixture at 55°C for 3 hours, then let it stand for 10 minutes. After separation, the aqueous phase of the reaction solution and the iodine-containing yellow phosphorus phase are obtained.

[0044] S3. Under ultrasonication at 30 kHz and stirring speed of 2 m / s, pure water at 60 ℃ is mixed with the iodine-containing yellow phosphorus phase from step S2 for washing. After standing and separating into layers, deiodized yellow phosphorus and aqueous washing solution are obtained. Deiodized yellow phosphorus is washed with hot water at 55 ℃ until the washing water is neutral to obtain low arsenic and low antimony yellow phosphorus.

[0045] S4. Combine the aqueous washing solution from step S3 and the aqueous reaction solution from step S2 to obtain an iodine-containing aqueous phase. Calculate the loss based on the content of iodine catalyst, oxidant, acidifier, and dispersant in the iodine-containing aqueous phase, replenish it, and add it to step S2. Replace the iodine catalyst and mixed solution with the iodine-containing aqueous phase in step S2, and repeat steps S2 to S4 to achieve the recycling of the iodine catalyst.

[0046] The iodine catalyst is elemental iodine, and its amount is 0.01 wt% of yellow phosphorus.

[0047] The oxidant is hydrogen peroxide, and its dosage is three times the mass of yellow phosphorus; the aqueous solution concentration of the oxidant is 5 wt%.

[0048] The acidifier is polyphosphoric acid, and the amount of acidifier used is 0.1 wt% of hydrogen peroxide. The mass concentration of phosphoric acid in the polyphosphoric acid is 115 wt%.

[0049] The dispersant is sodium lignosulfonate; the amount of dispersant used is 0.05 wt% of hydrogen peroxide.

[0050] At the end of each cycle, the loss is calculated based on the content of iodine catalyst, oxidant, acidifier, and dispersant in the iodine-containing aqueous phase, and timely replenishment is made in the next cycle.

[0051] Example 3

[0052] A method for recycling iodine catalyst in the production of low-arsenic and low-antimony yellow phosphorus includes the following steps:

[0053] S1. Mix the aqueous solution of the oxidant with the acidifier and dispersant, and preheat to 60°C to obtain a mixed solution;

[0054] S2. Preheat the yellow phosphorus to 60°C to fully liquefy it, and mix it with the mixed solution in step S1 and the iodine catalyst. Stir the mixture at 60°C for 2 hours, then let it stand for 20 minutes. After separation, the aqueous phase of the reaction solution and the iodine-containing yellow phosphorus phase are obtained.

[0055] S3. Under 50kHz ultrasound and 1m / s stirring speed, pure water at 65℃ is mixed with the iodine-containing yellow phosphorus phase from step S2 for washing. After standing and separating into layers, deiodized yellow phosphorus and aqueous washing solution are obtained. Deiodized yellow phosphorus is washed with hot water at 60℃ until the washing water is neutral to obtain low arsenic and low antimony yellow phosphorus.

[0056] S4. Combine the aqueous washing solution from step S3 and the aqueous reaction solution from step S2 to obtain an iodine-containing aqueous phase. Calculate the loss based on the content of iodine catalyst, oxidant, acidifier, and dispersant in the iodine-containing aqueous phase, replenish it, and add it to step S2. Replace the iodine catalyst and mixed solution with the iodine-containing aqueous phase. Repeat steps S2 to S4 to achieve the recycling of the iodine catalyst.

[0057] The iodine catalyst is elemental iodine, and its dosage is 0.05 wt% of yellow phosphorus.

[0058] The oxidant is hydrogen peroxide, and its dosage is 5 times the mass of yellow phosphorus; the aqueous solution concentration of the oxidant is 10 wt%.

[0059] The acidifier is a mixture of phosphoric acid and polyphosphoric acid (mass ratio 1:1). The amount of acidifier is 0.5 wt% of hydrogen peroxide, the concentration of phosphoric acid is 84 wt%, and the mass concentration of phosphoric acid in polyphosphoric acid is 105 wt%.

[0060] The dispersant is sodium lignosulfonate and polyethylene glycol (mass ratio 6:4); the amount of dispersant used is 0.07 wt% of the oxidant.

[0061] At the end of each cycle, the losses are calculated based on the content of iodine catalyst, oxidant, acidifier, and hydrogen peroxide in the iodine-containing aqueous phase, and timely replenishment is carried out in the next cycle.

[0062] Example 4

[0063] This embodiment provides a method for recycling iodine catalyst in the production of low-arsenic and low-antimony yellow phosphorus. The preparation method is basically the same as that in Example 1, except that hydroiodic acid is used as the iodine catalyst.

[0064] Example 5

[0065] This embodiment provides a method for recycling iodine catalyst in the production of low-arsenic and low-antimony yellow phosphorus. The preparation method is basically the same as that in Example 1, except that sodium iodide is used as the iodine catalyst.

[0066] Example 6

[0067] This embodiment provides a method for recycling iodine catalyst in the production of low-arsenic and low-antimony yellow phosphorus. The preparation method is basically the same as that in Example 1, except that the iodine catalyst uses elemental iodine and sodium iodide (mass ratio 8:2).

[0068] Example 7

[0069] This embodiment provides a method for recycling iodine catalyst in the production of low-arsenic and low-antimony yellow phosphorus. The preparation method is basically the same as that in Example 1, except that the iodine catalyst uses elemental iodine and sodium iodide (mass ratio 5:5).

[0070] Comparative Example 1

[0071] This comparative example provides a method for recycling iodine catalysts in the production of low-arsenic and low-antimony yellow phosphorus. The preparation method is basically the same as that in Example 1, except that ultrasound is not used in step S3.

[0072] Comparative Example 2

[0073] This comparative example provides a method for recycling iodine catalysts in the production of low-arsenic and low-antimony yellow phosphorus. The preparation method is basically the same as that in Example 1, except that an acidifying agent is not used.

[0074] Comparative Example 3

[0075] This comparative example provides a method for recycling iodine catalysts in the production of low-arsenic and low-antimony yellow phosphorus. The preparation method is basically the same as that in Example 1, except that a dispersant is not used.

[0076] Comparative Example 4

[0077] This comparative example provides a method for recycling iodine catalysts in the production of low-arsenic and low-antimony yellow phosphorus. The preparation method is basically the same as that in Example 1, except that nitric acid is used as the acidifying agent.

[0078] Comparative Example 5

[0079] This comparative example provides a method for recycling iodine catalysts in the production of low-arsenic, low-antimony yellow phosphorus. The preparation method is basically the same as that in Example 1, except that elemental bromine is used as the catalyst.

[0080] Comparative Example 6

[0081] This comparative example provides a method for recycling iodine catalysts in the production of low-arsenic, low-antimony yellow phosphorus. The preparation method is basically the same as that in Example 1, except that elemental bromine and sodium bromide (7:3) are used as catalysts.

[0082] Experimental Example 1

[0083] The recycling methods for iodine catalysts in the production of low-arsenic and low-antimony yellow phosphorus provided in Examples 1-7 and Comparative Examples 1-6 were used to perform 11 cycles each. The deiodinated yellow phosphorus prepared in the 2nd to 11th cycles was taken, and its arsenic content, antimony content, and yellow phosphorus yield were tested and the average values ​​were calculated. The results are shown in Table 1.

[0084] Table 1. Results of Deiodinated Yellow Phosphorus Detection

[0085]

[0086]

[0087] As shown in Table 1, the preparation methods of Examples 1-7 of this application can reduce the arsenic content in deiodinated yellow phosphorus to 0.1 ppm, the antimony content to undetectable levels, and the iodine content to 0.2 ppm, with a yellow phosphorus yield as high as 99.3%. In contrast, Comparative Example 1, which did not use ultrasonic operation, had no significant effect on the arsenic and antimony content, but the iodine content in the yellow phosphorus reached 25.1 ppm. In Comparative Examples 2-3, lacking acidifying agents and dispersants respectively, the arsenic and antimony contents increased significantly, and the yellow phosphorus yield also decreased significantly. Comparative Example 4, using nitric acid as an acidifying agent, showed a significant increase in arsenic and antimony contents. In Comparative Examples 5-6, using a bromine catalyst instead of an iodine catalyst, the arsenic and antimony contents of the products did not change much, indicating that the bromine catalyst also has a good catalytic effect.

[0088] Application Example 2

[0089] The recycling methods for iodine catalysts in the production of low-arsenic and low-antimony yellow phosphorus provided in Examples 1-7 and Comparative Examples 1-6 were used to perform 10 cycles each. The iodine-containing aqueous phase in step S4 of each cycle was taken, and the catalyst (iodine or bromine) recovery rate was tested and the average value was calculated. The results are shown in Table 2.

[0090] Table 2. Catalyst recovery test results

[0091]

[0092]

[0093] As shown in Table 2, the iodine recovery rate using the methods provided in Examples 1-7 of this invention is as high as 80% or more. Among these, when using a single catalyst, elemental iodine is slightly more effective than using hydroiodic acid and sodium iodide (Example 1 vs. Examples 4 and 5). Furthermore, the invention found that adding a certain amount of sodium iodide to elemental iodine (Example 6) significantly improves the iodine recovery rate, reaching nearly 90%. However, further increasing the sodium iodide content (Example 7) does not increase the iodine recovery rate; instead, it decreases.

[0094] In contrast, Comparative Example 1 reduced the ultrasonic operation, resulting in a significant decrease in iodine recovery, demonstrating the crucial role of ultrasound in iodine elution. Comparative Example 5 used elemental bromine as a catalyst, showing a very low bromine recovery rate, indicating that bromine cannot effectively recover the catalyst. Furthermore, attempts were made to use sodium bromide in the hope of improving bromine recovery as seen in Example 4, but unfortunately, similar properties were not observed with the bromine catalyst.

[0095] Further analysis and speculation revealed that during the removal of arsenic and antimony using an iodine catalyst, elemental iodine reacts with yellow phosphorus to form phosphorus triiodide, which then enters the iodine-containing yellow phosphorus phase. To recover the iodine, the phosphorus triiodide needs to be redissolved in the aqueous phase, as shown in the following equation:

[0096] (1) 2P + 3I2 → 2PI3

[0097] (2) PI3 + 3H2O → H3PO3 + 3HI

[0098] The generated HI will be oxidized into elemental iodine by the oxidant in the next cycle, and will regain its catalytic effect.

[0099] (3) 2HI + H₂O₂ → I₂ + 2H₂O

[0100] Based on the above principles, it can be assumed that a certain concentration of sodium ions promotes the hydrolysis of phosphorus triiodide, allowing more iodine to enter the aqueous phase, thereby increasing the iodine recovery rate. However, since the iodine catalyst itself is present in small amounts and is encapsulated by yellow phosphorus, adding ultrasound is a necessary step in this process, which explains the significant decrease in recovery rate in Comparative Example 1.

[0101] In summary, this invention utilizes an iodine catalyst to remove arsenic and antimony from yellow phosphorus, improving the quality of the yellow phosphorus. Simultaneously, it effectively recovers and recycles the iodine catalyst, reducing its consumption and thus conserving resources. The overall iodine recovery rate can reach over 80%, and the iodine consumption in the yellow phosphorus purification process is reduced from 0.01-0.1% of the yellow phosphorus mass to 0.2-2.0 ppm, demonstrating significant practical value.

[0102] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A method for recycling iodine catalyst in the production of low-arsenic and low-antimony yellow phosphorus, characterized in that, Includes the following steps: S1. Mix the aqueous solution of the oxidant with the acidifier and dispersant to obtain a mixed solution; S2. The mixed solution is mixed and stirred with liquefied yellow phosphorus and iodine catalyst, and then allowed to stand to obtain an aqueous phase and an iodine-containing yellow phosphorus phase; the iodine catalyst is a mixture of iodine agent and sodium iodide; the content of sodium iodide in the iodine catalyst is 10wt% to 30wt%; the iodine agent is at least one of elemental iodine or hydroiodic acid; S3. Under ultrasonic and stirring conditions, water is mixed with the iodine-containing yellow phosphorus phase for washing, and the mixture is allowed to stand and separate into layers to obtain deiodized yellow phosphorus and aqueous washing solution; the ultrasonic frequency is 30-100kHz, and the stirring linear velocity is 0.2-2m / s. S4. Combine the aqueous washing solution with the aqueous reaction solution to obtain an iodine-containing aqueous phase. Calculate the loss based on the content of iodine catalyst, oxidant, acidifier, and dispersant in the iodine-containing aqueous phase, replenish it, and then use the iodine-containing aqueous phase to replace the iodine catalyst and mixed solution used in subsequent S2 steps in the cycle.

2. The method for recycling iodine catalyst in the production of low-arsenic and low-antimony yellow phosphorus as described in claim 1, characterized in that: The amount of iodine catalyst added in S2 is 0.01 to 0.1 wt% of the yellow phosphorus.

3. The method for recycling iodine catalyst in the production of low-arsenic and low-antimony yellow phosphorus as described in claim 1, characterized in that: The oxidant is hydrogen peroxide, and the amount of the oxidant used is 3 to 7 times the mass of the yellow phosphorus; the concentration of the aqueous solution of the oxidant is 5 to 15 wt%.

4. The method for recycling iodine catalyst in the production of low-arsenic and low-antimony yellow phosphorus as described in claim 1, characterized in that: The acidifying agent is at least one of phosphoric acid and polyphosphoric acid; the amount of the acidifying agent is 0.1 to 1 wt% of the oxidizing agent.

5. The method for recycling iodine catalyst in the production of low-arsenic and low-antimony yellow phosphorus as described in claim 1, characterized in that: The dispersant is at least one of hexadecyltrimethylammonium bromide, sodium lignosulfonate, and polyethylene glycol; the amount of the dispersant is 0.05 to 0.1 wt% of the oxidant.

6. The method for recycling iodine catalyst in the production of low-arsenic and low-antimony yellow phosphorus as described in claim 1, characterized in that: The temperature of the liquefied yellow phosphorus in S2 is 50-70°C, and the reaction temperature of the yellow phosphorus with the mixed solution and the iodine catalyst is 55-65°C, with a reaction time of 1-3 hours.

7. The method for recycling iodine catalyst in the production of low-arsenic and low-antimony yellow phosphorus as described in claim 1, characterized in that: In step S3, the iodine-containing yellow phosphorus phase is mixed with pure water at 60-80°C and then washed with water at 55-70°C.

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