Applications of hearth (reverberatory) furnaces Hearth-type furnaces in industry may be used for roasting of ores, melting of metals, and reheating operations. Which statement best describes this usage?

Introduction / Context:
Hearth or reverberatory furnaces employ a refractory hearth on which the charge rests while hot gases circulate above it. They are widely used in metallurgy and materials processing for smelting, melting, reheating, and certain roasting operations, often with large radiant heat transfer areas.

Given Data / Assumptions:

• General industrial practice across ferrous and nonferrous sectors.
• Roasting refers to oxidizing heat treatment of sulfide ores; reheating refers to bringing stock to rolling/forging temperature; melting refers to liquefying metals/alloys.

Concept / Approach:
Because the charge is heated primarily by radiation and convection from hot combustion products, the same basic furnace layout can serve multiple purposes by adjusting temperature, atmosphere, and residence time. Historically, reverberatory and multiple-hearth variants have been applied to ore roasting, while open-hearth and other hearth-style furnaces have been used for melting and reheating.

Step-by-Step Solution:

Verification / Alternative check:
Industrial references document hearth-based roasting (e.g., multiple-hearth roasters), melting (open-hearth steelmaking historically), and reheating (soaking pits and reheating furnaces with hearths).

Why Other Options Are Wrong:

• Not used for roasting/melting/reheating: Each single exclusion contradicts established applications.
• Low-temperature drying only: Hearth furnaces routinely operate at high temperatures for metallurgical processes.

Common Pitfalls:
Confusing specific named furnace types with the broader “hearth furnace” family; many subtypes exist with overlapping capabilities.

Final Answer:
None of these (they can be used for all listed operations)