The problem of fertilizer caking usually occurs in the process of fertilizer processing, storage, transportation, which is caused by the moisture absorption, dissolution and evaporation of fertilizer grain, and recrystallization. In this process, a crystal bridge is formed, resulting in the formation of small particles into large particles and caking.
1. Choose suitable raw materials.
Most of the materials used in fertilizer production, such as ammonium salt, phosphate, trace element salt, potassium salt and so on, contain crystalline water and are easy to absorb moisture, such as ammonium sulfate, phosphate and trace elements are easy to agglomerate and become insoluble in water. Urea is easy to precipitate water and agglomerate when it meets trace element salts.
Choose raw materials that are not easy to cake and produce fertilizers that are not caking. For example, fertilizers with humic acid as the main raw material and fertilizers with amino acid as the main raw material are not easy to cake. In addition, when choosing materials, try to be as dry as possible.
2. When NPK fertilizer is produced, the moisture content of fertilizer and packaging temperature should be reduced, and the appropriate production time should be selected.
Fertilizer production is generally non-closed production. In the production process, the greater the air humidity, the easier the fertilizer to absorb moisture and agglomerate. Fertilizer production avoids the rainy season and concentrates on producing fertilizer on dry days. In the process of fertilizer production, the raw materials are heated by a dryer, so that the moisture content of the fertilizer is controlled below 0.6%, the cooling time of the fertilizer is prolonged, and the packaging temperature is lowered, so the fertilizer is not easy to cake.
3. Adding anti-caking agent to reduce the physicochemical reaction between NPK fertilizer particles.
The higher the room temperature, the easier it is to dissolve. Generally, raw materials dissolve in their own crystalline water and cause caking. Addition of talc powder, humic acid and other non-caking powder can also add some surfactants to prevent caking.
4. Reduce the stacking height and storage pressure of fertilizer.
The greater the external pressure of fertilizer, the easier the contact between crystal and crystal, the easier the caking; the smaller the external pressure, the more difficult the caking.
5. Precise screening of NPK fertilizer by screening machine can further improve the uniformity of fertilizer particles.
NPK fertilizer particles are not uniform in size, with small gap between particles and more contact area, it is easy to agglomerate. If the compressive strength of fertilizer granules is low, the fertilizer is easy to deform and break during packaging, transportation and storage, which will increase the contact area between granules and also lead to fertilizer caking.
If a fertilizer factory produces a large amount of fertilizer with NPK fertilizer production line, it can be screened twice with a screener machine to obtain suitable fertilizer granules.
6. Manufacture NPK fertilizer granules.
Because of the small contact area between the round particles, it is not easy to crystallize and agglomerate. Therefore, NPK fertilizer granulation is conducive to fertilizer storage, transportation and fertilization.
When NPK compound fertilizer granules are produced by roller press granulator, the dryer is not used, but the adhesion of raw materials for fertilizer production must be good.