Nitrophosphate fertilizers development

Nitric acid acidulation of phosphate rock produces phosphoric acid, together with dissolved calcium nitrate. Separation of the phosphoric acid for use as an intermediate in other fertilizer processes has not been developed commercially. Solvent extraction is less effective in the phosphoric—nitric system than in the phosphoric—hydrochloric system. Instead, the nitric acid acidulate is processed to produce nitrophosphate fertilizers. 

H. Storen, "The Nitrophosphate Process—an Alternative Route to Phosphate Fertilizers," ia proceedings of Phosphate Eertilicyers and the Environment, International Fertilizer Development Center, Muscle Shoals, Ala., 1992. 

Development of nitrophosphate fertilizer was started in Europe in the 1930s. Several processes were developed, and subsequent improvements have added to their efficiency and improved the quality of the producte. The jopularityTJ nitrophospfiaf m Europe has continued, and several plants have been built in other continents. Many of the plants are quite large and produce 1,500 or more tonnes of product per day. 

Conradsen, A., and G. Kongshaug. 1993. Nitro-phosphate Technology and the Environment, An Overview of Potential Sources of Pollution From an Integrated Nitrophosphate Fertilizer Production Complex, IN Nitric Acid-Based Fertilizers and the Environment, International Workshop Proceedings, pp. 135-151, R. G. Lee (Ed.), SP-21, International Fertilizer Development Center, Muscle Shoals, AL, U.S.A. 

The International Fertilizer Development Center conducts an annual survey of NPK granulation plants in the United States. By 1995 the number of operating plants decreased to only 25, from about 200 in 1965. No estimate has been made of the number of NPK granulation plants worldwide, but aImost-all-of-these-plants,-pIus-all nitrophosphate plants, incorporate secondary nutrients, primarily calcium and/or sulfur, in their products as the preferred, least expensive raw materials. Magnesium is different and is usually incorporated as a special additive. 

Diehl, L., R. E. Nitzschmann, and J.G.A. Reuvers. 1992. The BASF Nitrophosphate Concept Experience and Environmental Aspects Related to Three Recently Commissioned NPK Plants, INPhosphate Fertilizers and the Environment, Workshop Proceedings, pp, 241-250, J. J. Schultz (Ed.), SP-18, International Fertilizer Development Center, Miecle Shoals, AL, US.A. 

The first patent on ammonia oxidation wras issued to Khulman in 1839 in this case platinum was used as a catalyst to oxidize ammonia with air. The ammonia-oxidation method using a platinum catalyst qn a commercial scale, developed by Oswald and Brauer and first operated in Germany about 1908, is at present the principal industrial method of nitric acid producticxi. The main use for nitric acid is in fertiDzer production, mainly for ammonium nitrate as such or in compound fertilizers, nitrogen solutions, or mixed salts. About 75% of total nitric acid production is consumed for nitrate fertilizers, mainly as 509 5% concentration acid. Smaller fertilizer uses are for calcium and potassium nitrates. A primary use is in addulation of phosphate rock for production of nitrophosphates. Plant capacities for weak nitric acid i Bed for fertilizer production are in the range of 35 to 1,380 tpd althoi h capacities of 2,000 tpd have been designed. 

After the invention of this principle in 1928, ErBng Johnsen transferred his patent to Norsk Hydro A.S., which developed it in the 1930s and introduced its own technology in 1938. Norsk Hydro was among the first to produce multinutrient fertilizers - NPs and NPKs -via the nitrophosphate route. 

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