Potash salts make a significant contribution to food security
Without fertilisers, it is estimated that soil yields would fall to less than half. Potash salt is used as a fertiliser, nourishes plants and significantly increases soil yield.
Natural salts containing potassium are carnallite, kainite and sylvin. The potassium salts usually occur in combination with halite, which must be separated from the potash salt in a processing step. Here, hot dissolution processes, flotation and electrostatic separation are available. The first two processes are wet processes and the salt obtained must be dried.
The way the halite is separated has a direct influence on the quality of the potash salt and affects, for example, the design of a downstream drying plant.
In most cases, the fertilisers are granulated. This ensures that the fertiliser is evenly incorporated into the soil, because otherwise fine particles would dissolve too quickly and the long-term effect would be lost. Granulates are also much easier to dose.
Raw salt after hot dissolving or flotation is mechanically pre-dewatered and fed to thermal drying. Fluidised-bed drying using DRYON is a proven, reliable technology and shows significant savings in thermal energy. In the meantime, old drum dryers are being replaced by fluidised-bed dryers for energy reasons. For crude salt drying, a static DRYON is usually used.
For the production of granulates, water is added to finely ground fertiliser and rolled into larger agglomerates on a granulating plate, for example. Alternatively, fine material is pressed together under high pressing forces to produce pressed granules. This is usually broken into smaller granules and wetted with water and anti-caking agent.
In both cases, the granules have to be dried afterwards. Here, a vibrated fluidised bed technique has proven to be the perfect choice. Tests show that edges on the grain are removed and the grain is compacted. Furthermore, DRYON removes fine particles that could lead to caking of the product during subsequent transport or storage.