Manufacturing orthophosphoric acid (H3PO4): compared to the electric furnace route, the strong H2SO4 wet-process leaching route has which combined characteristics?

Introduction / Context:
Orthophosphoric acid is produced either by the electric furnace route (thermal process) or by the wet process using sulphuric acid to digest phosphate rock. Each route entails trade-offs in feed quality, capital cost, and product purity—knowledge pivotal for fertiliser complex design.

Given Data / Assumptions:

• Wet process digests phosphate rock with strong H2SO4.
• Electric furnace reduces phosphate rock to elemental phosphorus, then oxidises and hydrates it to H3PO4.
• Industrial goal: fertiliser-grade acid for downstream NP/NPK or high-purity for technical uses.

Concept / Approach:
The wet process tolerates lower-grade rock and requires less capital than the furnace route, but the produced acid contains more impurities (fluoride, metals, organics), making it fertiliser-grade unless further purified. The furnace process is capital- and energy-intensive but yields very pure acid suitable for food/technical uses.

Step-by-Step Solution:

Verification / Alternative check:
Industry practice dedicates wet-process acid to fertiliser manufacture, while furnace acid serves high-purity markets, confirming the comparative profile.

Why Other Options Are Wrong:

• Any single option (a, b, or c) alone is incomplete.
• Very costly (wet process) is incorrect; the furnace route is typically more capital- and energy-intensive.

Common Pitfalls:
Assuming “wet” implies impure in all cases; purification steps can upgrade quality but at added cost.

Final Answer:
all of (a), (b), and (c)