Ferrous metallurgy — route for manufacturing wrought iron from pig iron Wrought iron is obtained from pig iron mainly by which key refining process before subsequent consolidation steps?

Introduction / Context:
Traditional wrought iron production converts high-carbon pig iron into a low-carbon, slag-fibred product with excellent ductility and corrosion resistance. Understanding the historical process sequence clarifies which stage actually refines the hot metal chemically.

Given Data / Assumptions:

• Pig iron contains high carbon and impurities (Si, S, P).
• Puddling is a hearth-refining process in a reverberatory furnace.
• Shingling and rolling are mechanical working steps after refining.

Concept / Approach:
In puddling, pig iron is melted and stirred in an oxidizing environment so carbon and other impurities oxidize. The metal “comes to nature” as pasty balls of wrought iron which are later consolidated by shingling to squeeze out slag, and finally rolled into merchant bars.

Step-by-Step Solution:
Identify chemical refining: puddling oxidizes C, Si, Mn and reduces impurities.Post-refining consolidation: shingling welds the bloom and expels slag.Final shaping: rolling produces bars/plates.Therefore, the key process that transforms pig iron to wrought iron is puddling.

Verification / Alternative check:
Metallurgical histories and plant flowsheets list puddling → shingling → rolling as the classical route.

Why Other Options Are Wrong:
“Refining” is too generic; shingling and rolling are mechanical, not the primary refining stage; “all together” is incorrect because they are sequential distinct steps.

Common Pitfalls:
Confusing puddling with Bessemer/Siemens-Martin steelmaking; assuming rolling alone changes chemistry; overlooking the oxidizing atmosphere requirement.

Final Answer:
Puddling (in a reverberatory furnace)