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WEEK 7
TOPIC: IRON AND ALUMINUM
CONTENT:
- Extraction
- Types and uses
- Rusting of iron and methods of prevention iron
- Aluminium-extraction, properties and uses
Iron is a 3-d, block metal and transition element with atomic number 26. It has the symbol Fe with electronic configuration of 2, 8,14, 2 Iron is the second most abundant metal found in the earth crust. It is often found as iron ore. Examples include haematite (F2O4) the commonness magnetite (Fe O4), pyrites (Fe S3), spathic or siderite iron ore (Fe CO3), limonite (FeO3. H2O). It is present as trioxosilicates (iv) in clay soils. It is found in animal haemoglobin and plant chlorophyll. It can be found in Nigeria Anambra, Kogi and Edo state.
PERIOD 1: EXTRACTION
Iron ore is first roasted in air in a steel blast furnace so that iron (III) oxide is produced. The iron (III) oxide is then mixed with coke and limestone and heated to a very high temperature in the furnace. The ingredients are loaded into the furnace from the top while a blast of hot air is introduced from the bottom to the top through small pipes. The temperature inside the furnace varies from about 20000C near the bottom to about 2000C at the top.
- The oxygen in the hot air moving up oxides the hot coke coming down to Carbon (iv) oxide
C(s) + O2(g) → CO2(g)
- The CO2(g) is forced up to meet more hot coke which reduces it to carbon (II) oxide.
CO2(g) + C(s) → 2CO(g)
- The CO then reacts with Fe2O3, reducing it to Fe
Fe2O3(g) + 3CO(g) → 2Fe(l) + 3CO2(g)
The molten iron formed sinks to the bottom of the furnace, and is tapped off. The limestone present decomposes at high temperature to yield calcium oxide, which then combines with the silicon (iv) oxide (impurity) to form calcium trioxosilicated (iv)
PERIOD 2: TYPES AND USES
- Pig Iron: It is obtained direct the blast furnace and is quite impure. It contains 5% of carbon together with impurities like phosphorus, silicon etc. The presence of impurities lowers the melting point from 15300C to about 12000C. Dig iron is hard and brittle and can be used for industrial purposes.
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