Puddling (historic refining of pig iron to wrought iron): During the puddling process in a reverberatory furnace, which of the following statements are true regarding the metal–fuel separation, oxidation of impurities, and heating method?

Introduction / Context:
Puddling is a classic, now largely obsolete, furnace process used to refine pig iron into wrought iron. It relies on oxidation of impurities and furnace design that separates fuel from the molten bath. This question reviews core features of the process.

Given Data / Assumptions:

• Reverberatory furnace used (flame and hot gases sweep over the charge).
• Objective is to reduce carbon and remove other impurities by oxidation and slagging.

Concept / Approach:
In a reverberatory furnace, fuel burns on the grate, and hot products of combustion heat the metal bath indirectly. Stirring exposes fresh metal to oxidising conditions. Carbon oxidises predominantly to CO and CO2; silicon oxidises to silica and enters slag; phosphorus and other impurities also react and partition to slag under suitable conditions.

Step-by-Step Solution:

Verification / Alternative check:
Metallurgy texts describe puddling as an indirect-fired process, emphasising oxidation of carbon and slagging of silicon, sulfur, and phosphorus to produce malleable wrought iron blooms.

Why Other Options Are Wrong:
All individual statements A–D are correct descriptions, so the collective answer is “All of the above.”

Common Pitfalls:

• Confusing puddling with Bessemer blowing (which uses air blown through molten metal).
• Assuming fuel contacts the bath directly; it does not in reverberatory puddling.

Final Answer:
All of the above