Mining is a key global economic activity that has a millennia-old history and has evolved from simple surface resource exploitation in ancient times to the complex and vast quarrying and deep underground operations of today. This article will provide an overview of some of the main types of mining and how they differ from each other.
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The type of mining activity needed to exploit a particular resource depends on a few key factors. Firstly, the type of mineral excavated plays a key role in mine planning. Secondly, the location and position of the deposit must be carefully considered. Finally, the available volume of minerals influences the type of mine to be used. Considering these factors carefully during the planning phase will help mining companies ensure the economic viability of mines.
Surface Mining
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Surface mining is the oldest form of resource exploitation. The main difference between surface mining today and mining carried out in ancient times is the types of equipment used.
As some minerals exist at the surface or just below ground, surface mining is still the most appropriate method for extracting them. Surface mining is also referred to as open-pit mining.
Surface mining differs from other types of mining such as underground mining as it does not require the digging of deep shafts to access mineral ores. Only the overburden needs to be removed. This is the material located immediately above the coal seam or ore body. Overburden typically comprises soil, rocks, and plant life, but it can be composed of any ecosystem type.
Another key difference between surface mining and underground mining is the amount of work needed to extract the mineral resources. Open-pit mines tend to be safer than underground mines as workers can more easily evacuate disaster sites. However, there is still the danger of the open (or borrow) pit collapsing due to unstable rock faces or explosives use, so surface pits typically need to have stepped sides, which are otherwise known as benches.
Open-pit mines require a significant amount of space and may damage fragile ecosystems and contaminate groundwater, facilitating the need for environmental assessments and effective remediation strategies.
Underground Mining
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Some mineral deposits exist deep underground, facilitating the use of underground mines to recover them. Underground mining is inherently more dangerous than surface mining due to the deep location of mines.
Underground mining is one of the most common mining methods in use today.
The two main stages in underground mining are development (removing the unwanted and non-valuable rock and other components) and production mining (excavating the target resource.)
Depending on the processes employed to recover resources, extraction techniques, and shaft type, there are various categories of underground mining. Horizontal or vertical tunnels can be used, or a combination of both. Moreover, mineral type and geology influence the type of underground mining used.
Before an underground mine is excavated, a coal seam or orebody examination must be employed to determine the precise deposit location. This saves unnecessary work and financial expenditure and helps mine planners select the optimal mining technique. Moreover, efficient mine planning helps to avoid cave-ins and other disasters that can endanger the lives of mine workers. Special equipment is needed, especially if tunnels must be dug far underground.
Underground mines, while more dangerous and technically challenging, do not have as large an environmental footprint as surface mines. However, assessments must still be conducted on the surrounding geology of the deposit to avoid any risk of groundwater contamination.
In-situ Mining
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In-situ mining differs from underground and surface mining as it does not extract the ore and rock mix for processing at the surface of the mine. This type of mining is also termed in-situ leach mining.
In-situ mining involves using chemical solutions to dissolve the minerals and pump the pregnant solution out of the mine for processing. This type of mining is commonly used for the recovery of uranium due to its dissolvability.
A key consideration in in-situ mining operations is ensuring that the chemical leaching solution does not interact with the surrounding geology or potentially contaminate groundwater. In-situ mining cannot be used for gold, as it is easily dissolved.
Minerals must be permeable to the chemicals used for extraction. This requires evaluation of both minerals and the chemical solution to ensure efficient mixing and separation for processing. Specialist equipment must be used to help withstand the harsh chemicals used to extract mineral deposits.
Placer Mining
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Placer mining exploits unconsolidated minerals mixed with sediments. Rinsing and sifting are commonly employed to remove resources from mixtures.
Similar to gold panning, most placer mining operations are conducted in sandy areas and riverbeds where mineral deposits are located.
Resources typically recovered using this method include gold, precious gemstones, tin, titanium, and platinum.
Placer mining is a simple operation, but it requires extensive surveying of the target area to determine the amount of recoverable resources to ensure the economic viability of mining operations.
Some areas contain high concentrations of sediments, which can increase the amount of work needed to recover mineral resources.
Other Types of Mining
While these are the four main types of mining, there are many other mining methods that can be employed depending on the mineral deposit, location, and deposit volume.
These include longwall mining, mountaintop removal mining, dredging, highwall mining, block caving, cut-and-fill mining, and room-and-pillar underground mining.
References and Further Reading
Nayturr (2022) 10 Different Types of Mining Operations and Mines [online] nayturr.com. Available at: https://nayturr.com/types-of-mining/
An Underground Miner (2021) The Four Main Types of Mining [online] anundergroundminer.com. Available at: https://anundergroundminer.com/blog/the-four-main-types-of-mining
Cummins (2022) Types of Mining Methods [online] cummins.com. Available at: https://www.cummins.com/engines/mining/types-of-mining
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