Mining of elements began very early, probably since the dawn of human civilization. The period of the Copper Age, then the Bronze Age and the Iron Age are all testimony to the endeavor of humans to dig into the earth and extract minerals as and when they required. Since then mining has undergone a sea change but the basic process has more or less remained the same.
There are basically two types of mining:
- Open-cast or surface mining
- Underground mining
Surface mining – in this type of mining the minerals or rocks that are to be mined are exposed at the surface or very close to the surface. To extract the materials, earlier the miners used to dig an open-pit on the surface and then dig out the materials. But nowadays, giant earthmovers remove the top soil and the rocks and the material is extracted.
There are many types of surface mining processes. They are:
Strip mining process – as the name suggests the surface of the earth is stripped. In this process the soil and rocks that lie above is removed generally by heavy machinery and then the material is extracted. This type is possible only when the targeted materials are relatively near the surface. The mineral generally extracted is coal or some kinds of sedimentary rocks.
Placer mining process – in this process alluvial deposits in sand or gravel are extracted. This process does not involve the usage of any sort of heavy materials and can be considered relatively easy when compared to others. Generally gold and other gemstones are mined in this process.
Mountain top process – this process involves blasting of the top of mountains expose the coal below it. This process is relatively new.
Hydraulic mining process – in this process high pressure water jets are used to dislodge rocks and minerals. During earlier times gold was found in an easier way by this method. However, this process has been discontinued due to environmental concerns.
Dredging process – it is the process of underwater excavation by deepening a water body. In this method sediments and other substances are removed from harbors, rivers and other water bodies and minerals are extracted.
Open pit process – the easiest and the cheapest way to mine materials that are close to the surface, large open holes are dug in the ground. Sometimes, explosives are used to get large blocks of rocks out of the way.
Regarding underground mining there are five processes. They are:
Slope mining process – a type of underground mining, slopes are made into the ground and the desired material is accessed. This is done when the minerals are located far enough and surface mining cannot be employed to reach it. Generally, coal is mined in this way.
Hard rock process – here tunnels deep in the ground are dug sometimes with dynamite or large drills. The tunnels are supported by pillars through which miners can move about. Tin, lead, copper, silver, gold etc are mined with this process. This is typically the mine that comes to our minds when we think of it.
Drift mining process – this process is carried out when the material is situated sideways of a mountain. The materials are easier to access and the mouth is made slightly lower than the resource area so as to allow gravity to pull down the materials easily. Generally, coal or iron ore is mined through this process.
Shaft process – the deepest form of underground mining, this is done by excavating a vertical passageway deep down. The materials to be extracted are situated deep inside and elevators are used to take the miners up and down. It is kept in mind that the tunnels are made airy for miners to work without any problems. Generally, coal is mined in this process.
Borehole process – using a drill a deep hole is dug and a high pressure water-jet is used to force the materials up the hole. Sand, galena, gold etc are mined by this process.
The mining processes are interesting and the advancement in machinery has brought revolutionary changes in the mining process and safety of the miners. Many more innovations are carried on in this field.
James Wattson is a mining engineer and writes informative articles about mining safety and procedure, how ever in these days he is also busy dealing with various health and safety projects and this also reflects in his recent articles about TAE40110 , Training and Assessment , how to manage traffic in site and many more.