Question

Name the sulphide ore of Copper. Describe how pure copper is extracted from this ore.

Answer 1

Sulphide ore of copper is copper glance $C{u}_{2}S$.

The extraction of metals from ores involve three major steps:

1. Concentration of the ore,

2. Isolation of the metal from its concentrated ore, and

3. Purification of the metal

For sulphide ores, Froth floatation method is used to concentrate the ore by removing gangue particles from it. In this process, to an aqueous suspension of the powdered ore collectors and froth stabilisers are added. Collectors enhance hydrophobicity (non-wettability) of the mineral particles (such as pine oil) and froth stabilisers stabilise the froth (such as aniline). The mineral particles become wet by oils while the gangue particles by water. Upon agitaion by a rotating paddle, the mixture draws air and forms froth. This froth carries the mineral particle and being light is skimmed off from the surface. Upon drying ore particles are recovered.

Thus obtained $C{u}_{2}S$ may contain iorn as well as $FeS$, therefore it is mixed with silica and heated in a reverberatory furnace. In the furnace, iron oxide ‘slags of’ as iron silicate and copper is produced in the form of copper matte. This contains

$2FeS+3O_2\to 2FeO+2S{O}_2$

$FeO+Si{O}_2\to FeSi{O}_3\left(slag\right)$

$C{u}_{2}S$ and $FeS$ Copper matte is then charged into silica lined convertor. Some silica is also added and hot air blast is blown to convert the remaining $C{u}_{2}S/C{u}_{2}O$ to the metallic copper.

${2Cu}_{2}S+3O_2\to 2{Cu}_{2}O+2S{O}_2{2Cu}_{2}O+{Cu}_{2}S\to 6Cu+S{O}_2$

Thus obtained solidified copper has blistered appearance due to the evolution of $S{O}_2$ and therefore called blister copper.