Mixed fertilizers contain two or more of the elements nitrogen, phosphorous and potassium that are essential for good plant growth and greater crop yields. This document addresses the production of ammonium phosphates nitro phosphates potash and compound fertilizers.

Nitro phosphate fertilizers are made by digesting phosphate rock with nitric acid. The resulting solution is cooled to precipitate calcium nitrate which is removed by filtration. The filtrate is neutralized with ammonia and solution is then evaporated to reduce the water content. Periling may follow. The calcium nitrate filter cake can be further treated to produce a calcium nitrate fertilizer, pure calcium nitrate, or to give ammonium nitrate and calcium carbonate Nitrophosphate fertilizers are also produced by mixed acid process. Digestion of phosphate rock by a mixture of nitric acid and phosphoric acid.

• Raw materials required to produce NPK are rock phosphate, potash, urea and coating agent. Phosphates, potash and urea are fed to mixer in measured quantities. Mixed material is then fed to granulator, where coating agents are added.
• The granulator discharge is then dried in the dryer. The dryer discharge is then fed to cooler. Dried and cooled NPK is then fed to storage hopper. Finally, packing is done using automated machines.