Enriched superphosphate

A modification of the NSP production process involves use of a mixture of sulfuric and phosphoric acids. The resultant product is referred to as enriched superphosphate and can contain up to 40% P2O5. The usual P2O5 content of enriched superphosphate is about 27%. 

Enriched Superphosphate. This product, which is also referred to as double superphosphate, is essentially a mixture of SSP and TSP, usually made by acidulation of phosphate rock with a mixture of sulfuric and phosphoric acids. The desired concentration of mixed acid can be obtained by mixing concentrated sulfuric acid (93 or 98% H2S04) with dilute phosphoric acid (30%) thus avoiding the need for concentrating the latter. Production processes and equipment are about the same as for SSP20... 

Theoretically, any grade between SSP and TSP can be produced, but the usual range is 25-35 percent P205. The product is useful in sulfur-deficient areas where SSP would supply more sulfur than necessary. Only a small amount of enriched superphosphate is produced and used in Australia. 

Establishments primarily engaged in manufacturing phosphatic fertilizer materials, or mixed fertilizers from phosphatic materials produced in the same establishment. Included are phosphoric acid normal, enriched, and concentrated superphosphates ammonium phosphates nitrophosphates and calcium metaphosphates. 

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