The process of strong heating of sulphide ores in the presence of excess air to convert them into metal oxides is known as Roasting.
It is easier to obtain metal from its oxide, as compared to its sulphides and carbonates.
Hence, prior to reduction, the metal sulphides and carbonates must be converted into metal oxides.
Calcination is defined as the process of converting ore into an oxide by heating it strongly.
The ore is heated below its melting point either in absence of air or in limited supply.
Both Roasting and calcination are processes used in the refinement of ores and extraction of metals.
Process
Definition
Anodising
Process of covering the metals (mostlyaluminium and its alloys) with theirmetal oxides to prevent the metals fromcorrosion.
Composting
The process of letting the organicmatter decay, and decompose naturallyto convert it into a nutrient rich matter,which can be used as a natural fertilizer.