Main Granulating Methods of NPK Compound Fertilizer Production

NPK fertilizer can supply many kinds of nutrients needed by crops at the same time. The economic benefit is obvious. The production cost can be reduced by using compound fertilizer.

Compound fertilizer is not easy to agglomerate, easy to store and use, and is widely welcomed. How to select granulator for NPK fertilizer production line? Several main granulation methods are introduced here.

1. Solid aggregate method

The basic monomer fertilizers such as urea, ammonium nitrate, ammonium chloride, ammonium sulfate, monoammonium phosphate, diammonium phosphate and potassium chloride are used as raw materials. After crushing to a certain fineness, the materials are agglomerated and granulated in a disc fertilizer granulator (or rotary drum granulator) by adding water and heating. NPK compound fertilizer products can be obtained by drying, cooling and sieving granules, which is also one of the widely used methods in the world.

This method has a wide range of raw materials, simple processing process, less investment, low production cost, flexibility, and raw materials are solid. Because it is a secondary process of basic fertilizer, there is almost no environmental pollution problem.

2. Bulk blending method

According to the requirement of nutrient distribution ratio, mixed fertilizers with uniform nutrient distribution were prepared from various solid basic fertilizers of nitrogen, phosphorus and potassium without obvious chemical reaction, with basically identical granularity and roundness. The process of this method is simple and the investment cost is low, mainly use bulk blending mixer. It is a very practical and easy to promote method.

Bulk blending fertilizer has comprehensive nutrients, high concentration and flexible formula. It can be flexibly changed according to the different conditions of crop nutrition, soil fertility and yield level. Bulk blending fertilizer machine is simple in processing, low in production cost and pollution-free.

3. Extrusion method

Extrusion granulation is a dry granulation process in which solid materials are agglomerated by external pressure. Double roller press granulator is mainly used for granulation. The machine have two shaft with one fixed and the other can move, which can adjust the distance between the two shafts. And the granules will be extrude between the shafts.

Extrusion method of NPK fertilizer production has the following advantages:

(1) Drying and cooling processes are generally not needed in the production process, which can save investment and energy consumption.

(2) The operation is simple and there is no three wastes discharged during production.

(3) High-concentration compound fertilizer with lower concentration than general compound fertilizer can be produced. Organic fertilizer and other nutrients can also be added in production according to need. The production capacity of a single extruder is small. If large-scale production is needed, it can be combined with multiple units for factory production.