Compound fertilizer extrusion granulator commonly have roller extrusion granulator, flat (ring) mold extrusion granulator. In the process of compound fertilizer processing, these granulators may increase nitrogen according to the needs. Some use urea as the source of nitrogen, which is easy to absorb moisture in the air, resulting in the binding of compound fertilizer particles. Therefore, the extruding granulator is a dry powder granulator, which has a good effect on the processing of raw materials with low water content. It is necessary to carry out necessary anti hardening technology for wet materials.
Principle and moisture requirement of compound fertilizer granulator
The working principle of extrusion granulator is mainly dry powder. When the brittle material is extruded, some particles are crushed and the fine powder fills the gap between particles. In this case, if the free chemical bond on the newly generated surface cannot be quickly saturated by atoms or molecules from the surrounding atmosphere, the newly generated surface will contact each other and form a strong recombination bond. For roll extrusion, the roll skin has a spherical groove, extruded into a ball, and the particles extruded by the flat die are columnar.
In the granulation process of compound fertilizer, the crux of hardening is the high water content caused by the water absorption of urea. From the mechanism, the initiation and speed of slow combustion of compound fertilizer did not increase with the increase of ammonium nitrate and potassium chloride content. Compound fertilizer with urea as nitrogen source has high hygroscopicity and low softening point; biuret and adduct are easily formed at high temperature; urea will hydrolyze at high temperature, resulting in ammonia loss.
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