Chemistry · Ch 6 — General Principles and Processes of Isolation of Elements

Uses of Aluminium, Copper, Zinc and Iron

6.8

Extraction and refining only matter because these metals go on to do real work. A quick tour of where each one ends up:

Rolled into foil for wrapping food.
Powdered into fine dust for paints and lacquers.
Because it is itself highly reactive, used as a reducing agent in extracting chromium and manganese from their oxides (a thermite-type reaction).
Drawn into wire for carrying electricity.
Its light weight makes aluminium alloys valuable across countless applications.

The default choice for electrical wiring and for water/steam pipes.
Alloyed to gain toughness the pure metal doesn't have: brass (with zinc), bronze (with tin), and coinage alloys (with nickel).

Used to galvanise iron, protecting it from rusting.
Consumed in large quantities inside batteries.
A key ingredient of alloys — brass (Cu 60%, Zn 40%) and german silver (Cu 25–30%, Zn 25–30%, Ni 40–50%).
Zinc dust doubles as a reducing agent in manufacturing dyes and paints.

Cast iron, the most widely used form, goes into stoves, railway sleepers, gutter pipes, and toys, and also feeds into making wrought iron and steel.
Wrought iron is worked into anchors, wires, bolts, chains, and agricultural tools.
Steel, alloyed with other metals, branches into specialised grades: nickel steel for cables, automobile and aeroplane parts, pendulums, and measuring tapes; chrome steel for cutting tools and crushing machinery; and stainless steel for cycles, automobiles, utensils, and pens.

Table 6.2 ties the whole chapter together — occurrence, extraction method, and a defining remark for each of the four metals:

Metal	Occurrence	Common method of extraction	Remarks
Aluminium	1. Bauxite, $Al_2O_3.xH_2O$ 2. Cryolite, $Na_3AlF_6$	Electrolysis of $Al_2O_3$ dissolved in molten $Na_3AlF_6$	For the extraction, a good source of electricity is required.
Iron	1. Haematite, $Fe_2O_3$ 2. Magnetite, $Fe_3O_4$	Reduction of the oxide with CO and coke in Blast furnace	Temperature approaching 2170 K is required.

Table 6.2A Summary of the Occurrence and Extraction of some Metals is Presented in the following Table

Metal	Occurrence	Common method of extraction	Remarks
Aluminium	1. Bauxite, Al2O3.xH2O

Cryolite, Na3AlF6 | Electrolysis of Al2O3 dissolved in molten Na3AlF6 | For the extraction, a good source of electricity is required. | | Iron | 1. Haematite, Fe2O3
Magnetite, Fe3O4 | Reduction of the oxide with CO and coke in Blast furnace | Temperature approaching 2170 K is required. | | Copper | 1. Copper pyrites, CuFeS2
Copper glance, Cu2S
Malachite, CuCO3.Cu(OH)2
Cuprite, Cu2O | Roasting of sulphide partially and reduction | It is self reduction in a specially designed converter. The reduction takes place easily. Sulphuric acid leaching is also used in hydrometallurgy for low grade ores. | …