Ores and Metallurgy
1.0 Basic Definitions
1.0 Basic Definitions
The earth’s crust is the source of many metals. The occurrence of metal in native or in combined state in the earth’s crust along with a number of rocky and other impurities depends upon the chemical nature of metals. Metals having less electro-positive character have less affinity for oxygen and occur in free or native state e.g. $Ag$, $Au$, $Pt$ while metals with higher electro-positive character occur in combined state.
Oxygen is the most abundant element present in earth crust and iron comes second. The percentage of different elements in earth crust is:
Element | $\% $ by mass |
O | 49 |
Si | 26 |
Al | 7.5 |
Fe | 4.2 |
Ca | 3.2 |
Na | 2.4 |
K | 2.3 |
Mg | 2.3 |
H | 1 |
Other Elements | 2 |
The natural occurring chemical substances in the earth’s crust are called Minerals.
Those materials from which the metal can be extracted conveniently, economically and in large quantity are called Ores. Thus all the ores are minerals but all the minerals are not ores.
Metallic ores are often found to contain earthy or undesired materials such as sand, clay, quartz, silicates, mica etc. These unwanted impurities are called Gangue or Matrix.
