How to avoid ammonium sufate granular caking?
It is well known that ammonium sulfate crystals tend to form cakes of varying sizes and hardness. Caking is the formation of a mass or lumps of fertilizer product. It is a common situation that happened during production and storage largely affecting transportation and application. The caking characteristic of ammonium sulfate crystals presents an important problem in the manufacture and sale of ammonium sulphate. It cannot be applied to the soil by conventional chemical fertilizer distributing devices without prior crushing or grinding the lump. But Proper handling ensures the product keeps free-flowing throughout storage.
First, we need to know why the ammonium sulfate is Caking. Here we reveal the various reasons for you.
- Critical relative humidity (CRH)
The most common outcome of moisture absorption is caking. Each of the raw materials has a certain degree of hygroscopicity. Between the constituents on the surface of fertilizer granules, some chemical reactions will happen, giving rise to the phenomenon of recrystallization. When there is lower than the air’s relative humidity, they will absorb water from the air. The lower the value of CRH, the higher the hygroscopicity is, while higher moisture content brings about chemical reactions easily, and thus the phenomenon of caking is heavier. Usually, a fertilizer that has a higher content of nitrogen is more easily to cake. This tendency is particularly noticeable when ammonium sulphate crystals are exposed to increasing humidity conditions during storage and is especially aggravated in areas of relatively low humidity. - Shape of Granules
The higher the moisture content of the granules, the easier the process of dissolution and crystallization is going on. On the other hand, moisture will soften the granules, and make them deformed under pressure, so that the contact area among granules is enlarged, and the granules are more easily to be bonded to cake.
Small granules are more easily to cake than large ones. When the size gets larger, the specific surface area will decrease, then the contact area of adjacent granules is reduced, and the tendency of caking is lowered.
If the surface of the granules is smooth and the size is uniform, then the contact area is reduced.
If the granules are not uniform, or there are too many small particles, or the shape is not so round, then the particle strength is low, and the granules are prone to efflorescence or deformation under high pressure. The fine power largely enlarges the contact area and causes caking. - Temperature
If the environmental temperature during storage is too high, the CRH will decrease, its hygroscopicity will increase, and the fertilizer is easy to cake.
If packing and keeping the fertilizer in storage while the dried granules are not fully cooled, especially when the storage temperature is high, the internal water of the fertilizer will evaporate again. When the vapor meets the cooled external fertilizer, it will condense to water, and recrystallization will occur. - Stack Height
The higher the stack, the higher the stack pressure and the larger the plastic deformation of ammonium sulphate granules as well as the contact area, creating good conditions for chemical reaction and recrystallization. - Storage Time
With the extension of storage time, the recrystallization and dissolution process takes place again and again. A long time under pressure makes the deformation of fertilizer larger, and the tendency of caking is more obvious. - Hardness
The contact area of different granular and dust content will be minimized with higher hardness, recrystallization is more difficult. - Rough handling
Excessive careless loading and unloading, or transfer on the bumpy road can lead to dust formation due to product degradation. Dust results in a larger surface area of the product to absorb moisture.
To summarize, it’s caused by the formation of salt by crystal bridges between ammonium sulfate particles. According to this starting point, Hizens designed various options and compared the effects after implementation. So long as you adopt the right solutions as below, you can ease the problem of caking.
Tips for Preserving caking of Ammonium Sulphate in Storage
Synthesize to the above methods, we can avoid recrystallization caused by crystal bridges. The resulting ammonium sulphate product will be free-flowing and retains its non-caking properties through long storage periods.
If you have different or new opinions, you can email us (info@hizens.com) to discuss them together. Any competitor can also be involved. We are open to everyone.
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