Calcium nitrate, also known as Norwegian saltpetre, is an inorganic salt. Besides many other applications, it is mainly used as a component in mineral fertilisers. For this purpose, the mostly double salt 5Ca(NO3)2·NH4NO3·10H2O is used. However, a formulation without ammonia, Ca(NO3)2·4H2O, and a complex with urea Ca(NO3)2·4[OC(NH2)2]can also be used.
A process for producing calcium nitrate fertilisers was developed by the Research and Development Centre of VUCHT, in Slovakia. The very first plant based on the process has been operated by Slovak fertilisers producer Duslo, a.s. Later, a second plant was built at Lovochemie, a.s. Both companies are members of Agrofert Holding.
The process is based on the treatment of limestone with nitric acid, followed by neutralisation with ammonia. The process was tailored to the specific quality of the raw materials, particular product properties, and requirements of the state authorities.
Three quality grades can be produced by the process – Greenhouse Grade, Agriculture Grade and Fertigration Grade.
The production process is discussed, as well as the quality specification of the products. Troubleshooting that was required after the start-up is described. Investigation of problems that occurred during operation showed non-conformities between the limestone raw material and the designed quality specification. Unexpected contamination of the limestone by bitumen impurities was found, which caused several problems in the production process.
Branislav Brežný, VUCHT a.s., Bratislava, Slovakia.
19 pages, 9 figures, 2 plates, 5 tables, 18 references