Metallurgy — which process converts forge pig (white pig) into wrought iron in traditional practice? Choose the correct refining method.

Introduction / Context:
Classic ironmaking involves transforming pig iron into tougher, ductile wrought iron by lowering carbon and removing impurities. The historical route relied on the puddling process before modern steelmaking displaced it. This question ensures you can distinguish between the key processing stages and identify which one actually performs the chemical conversion from high-carbon pig iron to low-carbon wrought iron.

Given Data / Assumptions:

• Forge pig (white pig) is the input material.
• Traditional sequence: puddling → shingling → rolling.
• Goal: reduce carbon, sulfur, phosphorus to produce wrought iron.

Concept / Approach:
Puddling is a refining process carried out in a reverberatory furnace. The bath of molten pig iron is stirred (puddled) in an oxidizing environment so that carbon and other impurities are burned out or absorbed into slag. Wrought iron blooms form as decarburization proceeds. Subsequent operations consolidate the bloom and shape the product but do not perform the primary chemical refining.

Step-by-Step Solution:

Verification / Alternative check:
Metallurgy texts consistently describe puddling as the conversion step. Shingling and rolling are mechanical finishing processes following chemical refining.

Why Other Options Are Wrong:

• Rolling: Shapes and sizes the product; does not decarburize.
• Shingling: Consolidates bloom and squeezes out slag; not the primary refining step.
• Refining (generic): Too vague; the specific historical process is puddling.

Common Pitfalls:
Confusing mechanical working with chemical refining; both are essential but only puddling converts pig iron to wrought iron.

Final Answer:
Puddling