Mining is the extraction of valuable minerals, liquids and gases from the earth which are present as orebodies, veins, seams or liquids. Mining is required to obtain any non-renewable resource that can`t be grown or created artificially in a factory or laboratory.
Typical materials which are mined are: iron, coal, diamonds, base metals, oil shale, petroleum, etc.
This can be done in two ways:
Surface mining: Where surface vegetation, dirt and sometimes rock is removed to reach buried deposits. This can be done as open pit mining, quarrying,and strip mining.
Underground mining: Where shafts or tunnels are dug into the earth to reach buried ore deposits. This type of mining is classified by the (a) method of access, (b) the type of extraction or (c) the particular technique used to reach the orebody, e.g. (a) slope mining, shaft mining; (b) longwall mining, room and pillar mining; (c) bore hole mining, drift and fill mining.
Very heavy machinery is needed in all areas of mining: exploration and development; removal and stockpiling of overburden (the material above the ore which has to be replaced when mining ceases); for breaking, drilling and removing ore and rock of differing hardness; for carrying and processing material and for transporting it long distances to ports etc for export.
Typical types of machinery needed to accomplish these tasks are: large drills to sink shafts, obtain samples; trams and trains to transport miners and minerals; lifts for carrying ore, miners and machinery in and out; huge trucks, shovels and cranes to move large amounts of ore and overburden; processing plants containing large crushers, mills, reactors, roasters to extract the particular mineral or metal from the ore.
This area has made dramatic improvements in the recent past. Improvements in mining methods, safety training, gas monitoring, electrical equipment and ventilation have reduced many of the risks of explosion, toxic gases, rock falls, etc. Improved safety training (inductions, correct machinery operation etc), has resulted in a reduction of fatalities by two thirds since 1990. The industry is working towards nil harm to workers, but mining is still a dangerous occupation which requires much emphasis on safety training.