NPK fertilizer is a fast-developing fertilizer in China. It is easy to agglomerate during production, storage, transportation, etc., affecting the normal production and operation activities of fertilizer production enterprises, the sales of middlemen and the use of users, and thus affecting the compound fertilizer. Promote the application. Fertilizer agglomeration has become a problem that must be faced in all aspects. At present, the main reasons for the agglomeration of compound fertilizer are as follows:
1. First from the raw material analysis, mainly the raw materials are easy to dissolve
In general, the main raw materials for NPK fertilizer production line
are urea, ammonium chloride, ammonium nitrate, ammonium sulfate, diammonium phosphate, monoammonium phosphate, potassium chloride, potassium sulfate, and the like. Composite fertilizers made from these easily soluble fertilizers are easily agglomerated during storage and transportation.
2. Other factors affecting fertilizer agglomeration
(1) High moisture content of fertilizer
The moisture content of the fertilizer is a factor of agglomeration of the fertilizer during storage. The higher the moisture content, the easier the salt in the fertilizer granules dissolves, the more likely the physicochemical reaction occurs, and the agglomeration is easily formed after recrystallization, and the dissolution is repeated - the crystallization process leads to severe agglomeration.
(2) The product has uneven particle size and low particle compressive strength
If the compressive strength of the fertilizer granules is low, the fertilizer will be easily deformed and broken during packaging
, transportation and storage, which will increase the contact area between the granules and easily lead to agglomeration of the fertilizer. The fertilizer granules are small or the particle size is not uniform, the sputum between the granules is small, the specific surface area is large, and the contact area between the granules is large, and the agglomeration is easy.
(3) Pressure between fertilizers during stacking
When the fertilizer is stored, the particles are in close contact with each other under the action of gravity, and the deformation is easy, the stacking height is about high, the fertilizer is subjected to higher pressure, the indirect contact of the particles is increased, and the more easily agglomerated.
(4) Long storage time
The longer the storage time of the fertilizer product, the recrystallization of the surface of the fertilizer granules - the more the dissolution process is carried out, and the agglomeration tendency is remarkable when the pressure is under a certain pressure for a long time.
(5) High packaging temperature
The packaging temperature is high, the product is not cooled enough, the internal moisture of the product is not fully released, and when the temperature is high, the solubility of the corresponding salt is large. During the storage process, the temperature decreases, the solubility of the salt decreases, and the supersaturation will precipitate. Crystallization produces a crystal bridge that causes agglomeration.
(6) There is a large amount of fertilizer powder when packaging
During the process of cooling and packaging the fertilizer particles, friction between the particles will generate a certain amount of dust. The dust exists between the particles, which acts as a “bridge”, which increases the contact area between the fertilizer particles and also causes the knot.
There are many reasons for the agglomeration of compound fertilizer. The usual method is to use a coating machine
to spray an oily paste anti-caking agent on the outer surface of the NPK fertilizer particles to prevent the reaction between the surface components of the particles and reduce The rate at which the particles absorb moisture, in addition, slows the migration of moisture from the mother liquor to the surface of the particles, reducing the likelihood of dissolution and recrystallization changes on the surface of the particles.