Thermal process identification:\nHeating a mixture of coke, sand (silica), and phosphate rock in an electric furnace is carried out for the manufacture of which principal product?

Introduction / Context:
Two broad industrial routes handle phosphate rock: the “wet process,” producing phosphoric acid and superphosphates via sulfuric or phosphoric acid, and the “thermal process,” producing elemental phosphorus in electric furnaces. Recognizing which inputs map to which output is foundational for chemical process selection and environmental controls.

Given Data / Assumptions:

• Feed solids: phosphate rock, silica (sand), and coke.
• Reactor: electric furnace at very high temperature.
• Target product in the thermal route: elemental phosphorus.

Concept / Approach:
In the thermal process, carbon reduces phosphate to elemental phosphorus gas while silica combines with calcium oxide to form a molten calcium silicate slag. The volatile P4 is then condensed under water to yield white/yellow phosphorus. Wet-process phosphoric acid and superphosphates are not produced in the electric furnace; they are made by acidulation at much lower temperatures and different unit operations (digesters, filters, granulators).

Step-by-Step Solution:

Verification / Alternative check:
Process descriptions show tap slag removal and P4 recovery under water—signatures of the electric furnace route.

Why Other Options Are Wrong:

• Phosphoric acid, SSP, TSP, and MAP involve acidulation with sulfuric or phosphoric acid and often granulation, not high-temperature carbothermic reduction.

Common Pitfalls:
Conflating similarly named “phosphate” products; remember: furnace → P4, wet process → acids/superphosphates.

Final Answer:
Elemental phosphorus (P4).