Phosphate rock is the raw material used in the manufacture of most commercial phosphate fertilizers. This rock is derived from naturally-occurring ores. In its unprocessed state, phosphate rock is not suitable for direct application, since the phosphorus it contains is insoluble. To transform the phosphorus into a plant-available form and to obtain a more concentrated product, phosphate rock is processed using sulphuric and/or phosphoric acid.
The process begins by grinding phosphate rock to a fine material. In the acidulation unit, the fine phosphate rock reacts with phosphoric and/or sulphuric acid, to yield powder superphosphate (SSP and TSP). The powder fertilizer is then fed to a steam granulation unit where it turns to be 2-4 mm granulated P fertilizer. Potash may also be fed together with the superphosphate to obtain various grades of PK fertilizers.
The NP and NPK fertilizers are produced in a multi-purpose granulation plant which is also equipped with a pipe reactor that enables to react ammonia with phosphoric acid to yield MAP/DAP mixture, which is granulated in situ along with the superphosphate, and optionally potash. Micronutrients like boron, manganese, cupper and zinc can be added to produce tailor-made fertilizers to meet special demands of the customers.