Method for producing sodium hexametaphosphate and controlling high chain length

Abstract

The invention discloses a method for producing sodium hexametaphosphate and controlling high chain length, which breaks through the limitation of the traditional process technology and adopts the following technical key points: a) changing the temperature of sodium hexametaphosphate in the melting process so as to control the polymerization degree of materials in the melting process; b) a raw material area of the smelting furnace is controllable, the proportion of a clinker area to the raw material area is adjusted, and liquid-phase materials are prevented from being instantly vaporized and exploded; and c) the added flux inhibitor participates in material reaction, metal ions are utilized, and the product is pollution-free. Based on the properties of different melting points of substances, metal ions are effectively utilized, the product does not generate new substances, application of the product is not affected, the process is optimized, risks generated by converting a liquid phase into a gas phase are avoided, and the method is safe, reliable and high in applicability.

Description

Technical Field

[0001] This patent relates to the technical field of sodium hexametaphosphate production, and specifically to a method for producing sodium hexametaphosphate with controlled high chain length. Background Art

[0002] The existing sodium hexametaphosphate production process generally uses sodium carbonate or liquid alkali and phosphoric acid (industrial grade or food grade) to produce it through neutralization reaction. According to the different requirements of various industries, by adjusting the pH and concentration of the neutralized liquid, and preventing crystallization at a certain temperature, it is input into a high-level storage tank after fine filtration, reacted at high temperature in the furnace, and finally obtained the product required by customers after quenching, crushing, powder screening, and packaging. Traditional production processes can often only control the production of sodium hexametaphosphate products with medium and low chain lengths. For products with high chain lengths, especially those with a chain length of more than 20, there is a problem of unstable control in production. In addition, there are high-risk safety issues in the traditional control process: liquid materials that have not been dehydrated directly enter the molten material in the high-temperature zone, causing an explosion. The above risks have curbed the stable production of high-chain-length products. Summary of the invention

[0003] The purpose of the present invention is to avoid the above-mentioned shortcomings without increasing equipment investment, and to obtain high-chain-length sodium hexametaphosphate by adjusting the melting point of the material and then stably controlling the degree of polymerization of the product.

[0004] A method for producing sodium hexametaphosphate with controlled high chain length comprises the following steps: S1. Stir and mix the sodium-containing compound, the flux inhibitor and the phosphoric acid, and carry out a neutralization reaction at 60°C to 80°C; S2. The liquid is heated at 400-600°C to remove moisture; S3. High temperature melting at 700-1000℃; S4. Rapid cooling and crushing to obtain high-chain-length sodium hexametaphosphate.

[0005] The sodium-containing compound is at least one of sodium carbonate or sodium hydroxide.

[0006] The flux inhibitor is a high melting point sodium salt with a melting point of 800-900° C., preferably sodium chloride.

[0007] The phosphoric acid is food grade or industrial grade, and has a phosphoric acid content of 85%.

[0008] Calculated by mass fraction, the amount of each raw material is as follows: sodium compound 30~35%, flux inhibitor 0.03~5%, phosphoric acid 60-67%.

[0009] S2 and S3 are carried out in a high-temperature reaction furnace, which is divided into a raw material section and a clinker section. S2 is carried out in the raw material section, and S3 is carried out in the clinker section.

[0010] The mass ratio of the materials in the raw material section and the clinker section is 1:1-3.

[0011] The mass ratio of the materials in the raw material section and the clinker section is 1:3.

[0012] The reaction time of S1 is 2 to 4 hours; the reaction time of S3 is 0.5 to 1 hour.

[0013] The high-chain sodium hexametaphosphate has a chain length of 18 to 24, a pH of 6.0 to 6.5, and a total phosphorus content of 67.5 to 69.0%.

[0014] Compared with the prior art, the present invention has the following beneficial effects: The present invention adds a high melting point metal sodium salt as a flux inhibitor in the system for preparing sodium hexametaphosphate to adjust the melting point of the material; and also realizes stable and controllable production of high-chain length sodium hexametaphosphate by adjusting the reaction temperature and controlling the material ratio of the raw material section and the clinker section. DETAILED DESCRIPTION

[0015] The embodiments of the present invention will be described in detail below with reference to examples. The following examples are only used to illustrate the present invention and should not be construed as limiting the scope of the present invention.

[0016] Example 1 (Small batch test, melting in a reactor) Mix 30g of sodium carbonate, 1g of sodium chloride and 62g of phosphoric acid, stir at 60°C for 30min, and stir at a speed of 35 / min to complete the neutralization reaction; continue heating at 400°C for 30min to remove moisture from the material; then transfer the material to a reactor and melt react at 900°C for 30min; take out and quench, and crush to obtain sodium hexametaphosphate with a chain length of 20, a total phosphorus content of 68.8%, and a pH of 6.4.

[0017] Example 2 (Large-scale continuous production process, carried out in a high-temperature reaction furnace) 530kg of sodium carbonate, 0.5kg of sodium chloride and 1000kg of phosphoric acid were added to a neutralization reactor, stirred at 75°C for 180min, with a stirring speed of 60 / min; after the reaction, the materials were passed into a high-temperature reactor, which was divided into a raw material section and a clinker section. The materials first entered the raw material section, and the temperature of the raw material section was controlled at 400°C to remove moisture from the materials; after the moisture was removed, the materials entered the clinker section at a temperature of 900°C for melt polymerization; after polymerization for 1h, the materials were sent to a quencher for quenching, and then crushed to obtain sodium hexametaphosphate with a chain length of 20, a total phosphorus content of 68.8%, and a pH of 6.3; the mass ratio of the materials in the raw material section and the clinker section was 1:3.

[0018] Example 3 The same as Example 2, except that no sodium chloride was added; sodium hexametaphosphate with a chain length of 17 was obtained, the total phosphorus content was 68.5%, and pH=6.2. Example 4 The same as Example 2, except that the amount of sodium chloride added was 1 kg; sodium hexametaphosphate with a chain length of 22 was obtained, the total phosphorus content was 68.7%, and pH=6.3.

[0019] Example 5 The same as Example 2, except that the amount of sodium chloride added was 1 kg; the temperature of the clinker section was 800° C., the mass ratio of the materials in the raw section and the clinker section was 1:1, and sodium hexametaphosphate with a chain length of 21 was obtained, the total phosphorus content was 68.7%, and pH=6.3.

[0020] Example 6 The same as Example 2, except that the amount of sodium chloride added was 1 kg, and sodium hexametaphosphate with a chain length of 24 was obtained, the total phosphorus content was 68.9%, and pH=6.4.

[0021] Example 7 530kg of sodium carbonate and 1000kg of phosphoric acid were added to the neutralization reactor, stirred at 75°C for 180min, with a stirring speed of 60 / min; after the reaction, the materials were passed into a high-temperature reactor, which was divided into a raw material section and a clinker section. The materials first entered the raw material section, and the temperature of the raw material section was controlled at 300°C to remove moisture from the materials; after the moisture was removed, the materials entered the clinker section at a temperature of 620°C for melt polymerization; after polymerization for 0.5h, the materials were sent to a quencher for quenching, and then crushed to obtain sodium hexametaphosphate with a chain length of 12, a total phosphorus content of 68.3%, and a pH of 6.7; the ratio of the materials in the raw material section and the clinker section was 3:1.

Claims

1. A method for producing sodium hexametaphosphate to control high chain length, characterized in that: The following steps are involved: S1. Stir and mix the sodium-containing compound, the flux inhibitor and the phosphoric acid, and carry out a neutralization reaction at 60°C to 80°C; S2. The liquid is heated at 400-600°C to remove moisture; S3. High temperature melting at 700-1000℃; S4. Rapid cooling and crushing to obtain high-chain-length sodium hexametaphosphate.

2. A method for producing sodium hexametaphosphate and controlling high chain length according to claim 1, characterized in that: The sodium-containing compound is at least one of sodium carbonate or sodium hydroxide.

3. A method for producing sodium hexametaphosphate and controlling high chain length according to claim 1, characterized in that: The flux inhibitor is a high melting point sodium salt with a melting point of 800-900° C., preferably sodium chloride.

4. A method for producing sodium hexametaphosphate and controlling high chain length according to claim 1, characterized in that: The phosphoric acid is food grade or industrial grade, and has a phosphoric acid content of 85%.

5. A method for producing sodium hexametaphosphate and controlling high chain length according to claim 1, characterized in that: Calculated by mass fraction, the amount of each raw material is as follows: sodium compound 30~35%, flux inhibitor 0.03~5%, phosphoric acid 60-67%.

6. A method for producing sodium hexametaphosphate and controlling high chain length according to claim 1, characterized in that: S2 and S3 are carried out in a high-temperature reaction furnace, which is divided into a raw material section and a clinker section. S2 is carried out in the raw material section, and S3 is carried out in the clinker section.

7. A method for producing sodium hexametaphosphate and controlling high chain length according to claim 6, characterized in that: The mass ratio of the materials in the raw material section and the clinker section is 1:1-3.

8. A method for producing sodium hexametaphosphate and controlling high chain length according to claim 6, characterized in that: The mass ratio of the materials in the raw material section and the clinker section is 1:

3.

9. A method for producing sodium hexametaphosphate and controlling high chain length according to claim 1, characterized in that: The reaction time of S1 is 0.5-4h; the reaction time of S3 is 0.5-1h.

10. A method for producing sodium hexametaphosphate and controlling high chain length according to claim 1, characterized in that: The high-chain sodium hexametaphosphate has a chain length of 18 to 24, a pH of 6.0 to 6.5, and a total phosphorus content of 67.5 to 69.0%.