Q.How is 'cast iron' different from 'pig iron'?

Pig iron (93–97% Fe) is the impure iron collected directly at the bottom of the blast furnace, containing carbon plus impurities like Si, S, P, Mn, and is brittle and impure. Cast iron is obtained by melting pig iron with scrap iron and coke, giving a product with slightly lower carbon content that is extremely hard and brittle, used to cast stoves, pipes, gutter pipes and grills. …

Step 1 – Pig iron

Pig iron is the product obtained directly from the blast furnace as molten iron is tapped off at the bottom and allowed to solidify in moulds (traditionally called "pigs"). It typically contains about 93–97% iron, along with roughly 3–4% carbon and small amounts of other impurities such as silicon, sulphur, phosphorus and manganese picked up during the smelting process. Pig iron is hard, brittle, and of limited direct use; it is the crude starting material for further iron/steel processing.

Step 2 – Cast iron

Cast iron is made by re-melting pig iron together with scrap iron and coke in a furnace called a cupola. This re-melting step allows some further refinement/adjustment of composition, and cast iron typically has a slightly lower carbon content than pig iron (around 3%). It is extremely hard and brittle, and — as its name suggests — is directly cast into finished shapes such as stoves, pipes, gutter pipes, and decorative grills.

Step 3 – The essential distinction …

Distinguish by origin: pig iron comes straight out of the blast furnace; cast iron is made afterward by re-melting pig iron (with scrap + cok …

• Treating 'pig iron' and 'cast iron' as synonyms — they are related but sequential/distinct products. …