Product formed by phosphoric acid treatment of rock phosphate The action of phosphoric acid on rock phosphate (apatite) yields which fertilizer product under standard industrial practice?

Introduction / Context:
Phosphate fertilizers are made by “acidulating” phosphate rock. The acid used determines the product: sulfuric acid leads to single superphosphate (SSP), whereas phosphoric acid produces triple superphosphate (TSP). Understanding these routes is core to fertilizer process engineering and agronomy.

Given Data / Assumptions:

• Feed mineral: apatite-rich rock phosphate.
• Acid choices include H2SO4 and H3PO4 for common industrial routes.
• Objective: produce a plant-available phosphate product with desired P2O5 content.

Concept / Approach:
When rock phosphate is treated with phosphoric acid, the reaction forms monocalcium phosphate with higher P2O5 analysis and fewer impurities than SSP. This product is called triple superphosphate (typically around 44–48% P2O5). In contrast, sulfuric acid yields single superphosphate (~16–20% P2O5). Nitrophosphate comes from nitric acid digestion; DAP requires neutralizing phosphoric acid with ammonia, not direct rock acidulation.

Step-by-Step Solution:

Verification / Alternative check:
Process flowsheets in fertilizer texts show rock + H3PO4 → TSP granulation and curing, with higher P analysis than SSP.

Why Other Options Are Wrong:

• SSP: Produced using sulfuric acid, not phosphoric acid.
• Nitrophosphate: Requires nitric acid route.
• DAP: Formed by ammonia neutralization of phosphoric acid, not direct rock treatment.

Common Pitfalls:
Confusing SSP vs TSP based solely on granule appearance; the key difference is the acid used and resultant P2O5 content.

Final Answer:
triple superphosphate (TSP)