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Abstract

Process and Apparatus for preparing O--X--O and O--X--X (i.e., zero nitrogen) suspension fertilizers wherein phosphate rock is acidulated with merchant-grade wet-process orthophosphoric acid. The instant invention requires only a minimal amount of relatively inexpensive equipment. The process comprises a first-charging step wherein a reactor vessel is partially filled with water of formulation, phosphoric acid, and phosphate rock. The resulting mixture is subjected to a digestion step for a predetermined period of time to effect reaction of the acid and phosphate rock added thereto. Said digestion step is subsequently followed by a second-charging step wherein predetermined amounts of potassium chloride and/or suspending agent are added to said reactor vessel. The proportion of phosphate values won from the phosphate rock, the optimum length for the digestion period, and the grades of the final products recovered from the process of the instant invention are all factors which are in a dependent and substantially proportional relationship with the quality of the raw materials utilized therein. The highly concentrated suspension fertilizer products are suitable for use in commercially available fluid fertilizer application equipment by having a rheology such that the suspension fertilizers can be sprayed directly on to croplands, as for example those used to raise legumes, which croplands require fertilizer amendments having little or no nitrogen. In addition, the highly concentrated suspension fertilizer products exhibit very acceptable short-term storage properties.

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First Claim