Acidulation of phosphate rock:\nWhen calcium fluorapatite (phosphate rock) is treated with sulphuric acid under typical fertiliser conditions, what product is obtained?

Introduction / Context:
Manufacture of phosphate fertilisers begins by acidulating phosphate rock (chiefly calcium fluorapatite) with an acid. The choice of acid and its concentration determine whether the output is superphosphate, triple superphosphate, or phosphoric acid. The question asks for the product formed with sulphuric acid under standard single-superphosphate conditions.

Given Data / Assumptions:

• Reactant: calcium fluorapatite (phosphate rock).
• Acid: sulphuric acid (dilute to moderate strength for SSP).
• Conventional fertiliser process (wet acidulation), not pure phosphoric acid route.

Concept / Approach:
Reacting phosphate rock with sulphuric acid forms monocalcium phosphate monohydrate (the plant-available P component of SSP) and gypsum (CaSO4·2H2O) as a by-product. When phosphoric acid (not sulphuric) is used, triple superphosphate results. Wet-process phosphoric acid is made by digesting rock with excess sulphuric acid and separating gypsum; this is a different flowsheet.

Step-by-Step Solution:

Verification / Alternative check:
Process descriptions label SSP as rock + H2SO4; TSP as rock + H3PO4; wet-process H3PO4 requires filtration to remove gypsum.

Why Other Options Are Wrong:

• Orthophosphoric acid only: that is the wet-process acid route, not directly SSP.
• Triple superphosphate: requires phosphoric acid, not sulphuric.
• Red phosphorus: unrelated to wet acidulation.
• Dicalcium phosphate only: not the standard SSP product mixture.

Common Pitfalls:
Confusing the SSP (H2SO4) and TSP (H3PO4) flowsheets; forgetting gypsum is inevitably co-produced in SSP.

Final Answer:
Simple superphosphate (single superphosphate)