Chemical plant construction—sulphur melting pit materials in sulphuric acid manufacture Sulphur melting pits in sulphuric acid plants are commonly constructed from which material(s)?

Introduction / Context:
Prior to burning sulphur for sulphuric acid production, elemental sulphur is melted and filtered. The melting pit must tolerate molten sulphur temperatures, mechanical loading, and occasional impurities, while being economical and maintainable in a corrosive plant environment. Material selection balances temperature capability, corrosion behavior, and cost.

Given Data / Assumptions:

• Molten sulphur typically handled near 120 to 150 degrees Celsius.
• Environment is largely non-oxidizing for sulphur itself; heavy acids are not present in the pit.
• Structural robustness and practicality are required.

Concept / Approach:
Steel constructions or concrete pits lined with acid-resistant bricks or cement-brick linings are common. Sulphur at its melting temperature is not strongly corrosive to carbon steel or to suitable masonry linings, which explains the pervasive use of these economical materials. Lead lining is unnecessary and impractical here, and hardwood lacks temperature resistance and durability. Cast iron can be brittle and less favorable structurally for large pits compared to reinforced concrete or fabricated steel structures with appropriate linings.

Step-by-Step Solution:

Verification / Alternative check:
Industry practice and plant design literature show steel tanks with refractory or brick linings, or concrete pits lined with acid-resistant bricks, as standard for sulphur melting service.

Why Other Options Are Wrong:

• Lead lined stainless steel: excessive cost and unnecessary corrosion allowance for this duty.
• Cast iron: brittle and less favorable for large structural pits.
• Hard wood: inadequate temperature and chemical durability.

Common Pitfalls:
Confusing sulphur melting service with sulphuric acid storage; acid requires specific corrosion resistant alloys or linings, whereas molten sulphur service is less aggressive.

Final Answer:
steel or cement-brick lined.