Refining-of-Iron??????

Question

During the process of refining (converting) iron ore to iron,several materials are used .explain what part of each of these materials play in the refining process.

a-ironore,b-coke,c-limestone,d-hot air

Answer 1

- Iron ore.  Usually magnetite or haematite (iron oxide), sometimes limonite (iron hydroxide).

- Coke.  A source of carbon. The reducing agent. Under high temperature and in the presence of large volumes of air (blown through a blast furnace), the coke combines with the oxygen in the iron ore, to forn carbon dioxide, which is discharged to the atmosphere.

- Limestone, calcium carbonate. The flux.  The calcium carbonate is reduced to calcium oxide, which then combines with any silica impurities in the ore to form calcium silicate slag; which floats to the surface of the molten iron, and can be drawn off and disposed of (often crushed up and used as a roadmaking aggregate).

After removal of the slag; the molten iron which is rich in carbon ('pig iron') can be drawn from the bottom, and  further refined in an electric arc or open hearth furnace or a converter to make mild steel (after removal of the remaining carbon by blowing oxygen through the molten iron), or combined with other materials to make various steel products (eg; combined with chromium, stainless steel can be produced).

Answer 2

a Iron ore, which is usually hematite or magnetite, is the source of iron.b Coke, which is carbon is there to reduce the iron oxides to metallic    iron forming CO and CO2 in the process.c Limestone, which is calcium carbonate is added to make    the flux more fluid.d The air that feeds into the tuyeres at the base of a blast furnace is usually preheated to improve the overall efficiency of the furnace. Mike.