Particle coating is becoming increasingly important in fertilizer, pharmaceutical and food industries. The demand for coating granular fertilizers with minerals is increasing. Urea is coated with PhosphoGypsum, neem oil, polymeric suspensions and micronutrients like sulfer, zinc etc.Coating of PhosphoGypsum on urea fertilizer is a important application of coating process . Coating of urea particles is done to increase nitrogen use efficiency of urea. Nitrogen losses due to leaching, surface volatilization, and denitrification can be minimized by controlling the dissolution rate. Coating also helps to impart strength, increase in bulk density and lowering of caking tendency, thus improving the handling properties. The objective of present paper is to present the improvement in properties of urea obtained by fluidized bed coating of urea with Phosphogypsum using wet and dry methods.Emulsion of PhosphoGypsum, Neem (Azadirachta indica L.) oil, LAB (Linear Alkyl Benzene) and water was prepared in concentrations of 5%, 10% and 15%. Coating experiments were carried out with both PhosphoGypsum, Neem Oil, LAB and water (wet coating) and PhosphoGypsum, Neem Oil and LAB (dry coating) . PhosphoGypsum coated samples were analyzed for crushing strength, dissolution rate, dustiness factor and phosphogypsum content. Characterization of coated and uncoated urea prills is done to optimize and control the process of coating and also the performance of urea coating process can be checked which is useful for checking feasibility of this process on an industrial scale. The experimental results showed that wet method is better than dry method and 1.7 mm diameter size particle give better results than 1.4 mm size diameter particle. Dissolution rate, which is directly related to the nitrogen use efficiency is reduced as a result of coating, thus giving coated urea high moisture holding capacity.
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