A new choice for dry granulation: A comprehensive analysis of fertilizer granules compaction technology

Extrusion granulation (utilizing a double roller press granulator) relies solely on mechanical pressure to form granules from powder. Unlike wet granulation, which depends on moisture and heat, this method offers an energy-efficient, high-performance dry processing route for fertilizer production. 1.Process Principle: Physical Forming Under High Pressure Dry powder with a moisture content controlled below 5%–8% is fed between two counter-rotating rollers. Under high pressure, the material is forced into the mold cavities on the roller surfaces and instantly compacted into shape; after release from the rollers, the material is screened to yield the final granules. The entire process involves no added water, heat, or binders—relying purely on physical cold pressing. The workflow is streamlined: raw material crushing → precise proportioning → mixing → extrusion granulation → screening and packaging. 2.Technical Advantages: Energy Efficiency and Composition Integrity The primary advantage of fertilizer granules compaction technology lies in energy efficiency. By eliminating the drying and cooling stages required in wet granulation, overall energy consumption can be reduced by 30%–50%. Secondly, it ensures the integrity of the composition; since no water or binders are added, the product's N-P-K content aligns almost perfectly with the design formula, and there is no heat loss—making it particularly suitable for high-concentration compound fertilizers. Furthermore, the process offers great flexibility in formula switching, allowing for a transition between different formulations in just half an hour. The production process generates no wastewater or waste gas emissions, making it clean and environmentally friendly. 3.Limitations and Applicability Granules produced via extrusion tend to be flattened spheres or cylindrical in shape, lacking the high sphericity of wet-granulated products. The process imposes strict requirements on raw material moisture content and particle fineness. Additionally, the capacity of a single unit is limited, making it better suited for small- to medium-scale production. This technology demonstrates unique value in the production of compound fertilizers, organic-inorganic compound fertilizers, and slow-release fertilizers; its advantages—low investment, quick returns, and zero waste emissions—make it an ideal choice for small- and medium-sized projects.