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What is the difference between dry and wet granulation?

2023/01/06

 The granulation technology of npk production line is generally divided into wet granulation and dry granulation. The difference between dry granulation and wet granulation is whether a liquid solution is used. Dry granulation does not use liquid solutions such as water or binders, while wet granulation does.

dry granulation
Dry granulation traditionally refers to the extrusion granulation technique because no addition of water or binders is required in the npk fertilizer manufacturing process. In extrusion granulation, raw materials are agglomerated under high pressure into a primary powder, which is then squeezed between rollers to produce fertilizer granules. The finished fertilizer granules do not need to be dried or cooled, and can be packaged directly. Therefore, the dry granulation method is widely used in small and medium-sized fertilizer plants with low investment. Fertilizer granules produced by dry granulation are usually flat. Twin-roll extrusion granulator is the most widely used equipment in extrusion granulation technology.
Advantages of extrusion granulation technology
1. This extrusion granulation does not require drying and cooling processes.
2. The fertilizer granulation rate is high, and the final fertilizer granules are rough, but with high hardness.
3. This granulation technology can be used to produce low-concentration compound fertilizer.

wet granulation
Compared with dry granulation, the granular fertilizer produced by wet granulation has higher moisture content, so the finished product needs to be dried, cooled and solidified. In the wet granulation process, the most commonly used fertilizer granulators are drum granulators and disc granulators.
Drum granulator is the key equipment for producing high-concentration and low-concentration compound fertilizers in the fertilizer industry. The principle of the drum granulation process is that all raw materials roll and solidify in the drum, so that the raw materials can fully react. Through the rotating motion, the material particles are granulated into compound fertilizer balls under the action of pressure. Widely used in large npk fertilizer production line manufacturers.
The principle of disc granulation is to roll all the mixed raw materials in the swash plate, add binder and water to make fertilizer granules of different sizes. It is cheaper than drum granulator or other compound fertilizer equipment, the cost is reduced by 30%, and the production capacity is 1-4 tons/hour.