can be drawn into wires (are ductile), most have a silvery color, and none is
soluble in any ordinary solvent without a chemical change.
The general chemical properties of metals are: they are electropositive, and
the more active metallic oxides form bases, although some metals form
amphoteric hydroxides that can react as both acids and bases.
Some Important Reduction Methods of Iron Ore
Iron ore is refined by reduction in a blast furnace, that is, a large, cylinder-
shaped furnace charged with iron ore (usually hematite, Fe 2 O 3 ), limestone, and
coke. A hot air blast, often enriched with oxygen, is blown into the lower part of
the furnace through a series of pipes called tuyeres. The chemical reactions that
occur can be summarized as follows:
Burning coke:2C + O 2 → 2CO(g)C + O 2 → CO 2 (g)Reduction of CO 2 :
CO 2 + C → 2CO(g)Reduction of ore:Fe 2 O 3 + 3CO → 2Fe + 3CO 2 (g)Fe 2 O 3 + 3C → 2Fe + 3CO(g)Formation of slag:CaCO 3 → CaO + CO 2 (g)CaO + SiO 2 → CaSiO 3The molten iron from the blast furnace is called pig iron.
From pig iron, the molten metal may undergo one of three steel-making
processes that burn out impurities and set the contents of carbon, manganese,
sulfur, phosphorus, and silicon. Often nickel and chromium are alloyed in steel to
give the particular properties of hardness needed for tool parts. The three most
important means of making steel involve the basic oxygen, the open-hearth, and
the electric furnaces. The first two methods are the most common.
The basic oxygen furnace uses a lined “pot” into which the molten pig iron
is poured. Then a high-speed jet of oxygen is blown from a water-cooled lance
into the top of the pot. This “burns out” impurities to make a batch of steel rapidly
and cheaply.
The open-hearth furnace is a large oven containing a dish-shaped area to
hold the molten iron, scrap steel, and other additives with which it is charged.
Alternating blasts of flame are directed across the surface of the melted metal