Part 3 of a 5-part blog series: “The Bradley Broadfield superphosphate process”

The Broadfield process has remained a mainstay of the global phosphate industry since its introduction in the 1930s. In Part 1, Ian Hancock, Vice President Sales & Operations, Bradley Pulverizer, provides an introduction to the Bradley Superphosphate process, and in Part 2 we explore the origins of superphosphate manufacturing .  Click Here to download the complete article in pdf format as published by BCInsight Ltd in Fertilizer International Sept|Oct 2022, issue 510, pp. 31-35.

Our 5 part series explaining the Broadfield superphosphate process started with an introduction to the process, followed by a brief history of processes used for superphosphate production.  A more in-depth discussion is required to fully explain the chemical processes that transform phosphate rock into superphosphate fertilizer, but the formulas outlined below sufficiently highlight the major chemical reactions within the Broadfield process.

Single Superphosphate (SSP) is made by reacting non-soluble fluorapatite (the mineral present within phosphate rock) with sulphuric acid to produce soluble monocalcium phosphate and calcium sulphate. Gaseous by-products from the reaction include  and  (released from associated calcium carbonate in the rock). The overall chemical reaction is summarized in equation 1 below.

2Ca5(PO4)3F+6H2SO4+3H2O → 6CaSO4+3Ca(H2PO4)2∙H2O+CaF2

TSP is made by reacting the phosphate rock with phosphoric acid. The reaction is faster than for SSP as deposition of calcium phosphate on the rock surfaces, which slows diffusion, is avoided. The TSP obtained is also a better grade product with a higher concentration of monocalcium phosphate. The overall chemical reaction is summarized in equation 2 below.

2Ca5(PO4)3F+12H3PO4+9H2 O → 9Ca(H2PO4)2∙H2O+CaF2


Continue to Part 4 – Superphosphate Acidulation in the Broadfield Den

Back to Part 2 – Origins of Superphosphate Manufacturing

Contact Us to learn more about the superphosphate process and if it is right for your fertilizer manufacturing operations.

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