Surfactant is used as water reducing agent in the production of phosphorus compound fertilizer

2022-05-13 17:05:57

In the production of wet process phosphoric acid, adding surfactant can improve the habit of crystallization process and obtain coarse and easily filtered calcium sulfate crystal. For example, adding alkylbenzene sulfonic acid (ABS), isopropyl naphthalene sulfonate or decyl benzene sulfonate into the reaction system can inhibit the formation of dihydrate crystal nucleus, make the crystal grow coarser, and promote the dielectric stability of hemihydrate crystal at lower temperature, so as to improve the filtration rate of phosphogypsum crystal and reduce the loss of P2O5.

Water reducing agent is an additive that reduces the amount of water used without affecting the fluidity of slurry (or pulp).

One of the main fields of surfactant used as water reducer in the production of phosphorus compound fertilizer is the production of wet superphosphate. Wet grinding has the advantages of low noise and light environmental pollution. If the amount of water added is low, the viscosity of the pulp is too high, which is not conducive to the flow of the pulp, especially for hydrophilic phosphate rock; The high amount of water added will not only lead to poor physical properties and easy caking of products, but also make the water content of products exceed the standard and become unqualified products. Selecting appropriate water reducing agent can disperse phosphate rock particles, reduce the viscosity of pulp and enhance the fluidity of pulp.

Powdered fertilizer is increasingly neglected by the domestic market due to inconvenient storage and application. Southeast Asia, South Korea, Japan and other neighboring countries also have a certain demand for granular calcium magnesium phosphate fertilizer and calcium superphosphate. China's traditional powdery fertilizer varieties such as calcium magnesium phosphate fertilizer, calcium superphosphate and potassium chloride will be welcomed by users at home and abroad if they can be granulated.

Granular fertilizer is required to have good disintegration (i.e. quick dispersibility) when applied to the soil, so as to make the fertilizer have a large contact area with the soil and plant roots, which is conducive to the absorption of nutrients. Granular fertilizer disintegrating agent is added during fertilizer granulation, so that fertilizer particles can disintegrate in water or soil, dissolve or disperse in water and soil. Common surfactants used as disintegrating agents include C8 ~ C18 alkyl sulfonates α- Alkenyl sulfonate, fatty acid-n-methyltaurine, etc.