Cupola furnace practice for foundry: For melting approximately one tonne (1,000 kg) of cast iron in a conventional cupola, which of the following material and air requirements are commonly cited together?

Introduction / Context:

Cupola furnaces are traditional units for melting cast iron using coke as fuel, air blast for combustion, and flux (often limestone) to form slag with impurities. Rule-of-thumb operating figures help plan charge materials and blower capacity in small-to-medium foundries and appear frequently in examination questions.

Given Data / Assumptions:

• Tonnage target: ~1 tonne of molten cast iron.
• Conventional coke-fired cupola with limestone flux.
• Typical specific consumptions under steady, well-tuned operation.

Concept / Approach:

Representative guidelines state that melting 1 tonne of cast iron may require on the order of 700 m³ of air, roughly one quintal (≈100 kg) of coke (≈10% fuel-to-iron by mass, depending on efficiency), and around 20 kg of limestone (flux demand depends on sulphur and ash). While actual values vary with iron quality, coke ash/sulphur, blast rate, and lining condition, these figures are widely taught as ballpark numbers.

Step-by-Step Solution:

Verification / Alternative check:

Charge calculations often start from specific coke rate (8–14%), flux-to-coke ratio (≈0.2), and blower sizing (air per tonne/hour), supporting the listed magnitudes for a one-tonne melt.

Why Other Options Are Wrong:

• Each individual statement is plausible, but the question asks which set is correct together; selecting only one omits the others.
• None of these contradicts standard practice.

Common Pitfalls:

• Treating the rules of thumb as exact constants; real plants tune to material and furnace conditions.
• Ignoring preheat and metallic returns, which can slightly alter fuel demand.

Final Answer:

all the above