Types Of Mining Operations
Mining is an integral part of our industry and resources. It provides hundreds of thousands of well paying jobs and it provides a larger portion of our GDP. There are several main types of mining operations that are conducted.
Placer mining defines any type of mining where the raw minerals or ore is located in either in sand, gravel, or on the surface so it is retrievable without the use of dynamite or other extraordinairy means. Placer means “sand bank” in Spanish so the term is very appropriate to the type of mining.
There are different types of placer mining which include sluicing, dredging, and panning. In sluicing the placer gravel is shoveled into a sluice box which sits on an incline. The sluice box has a mix of traps and riffles that catch the material as it passes through. Water is fed into the sluice and the riffles trap the heavy minerals.
Sluicing allows the capturing of very fine gold particles as does panning. Panning is a method used by hobbyists and personal miners using a gold pan. The pan is moved in a circular motion which removes waste material leaving the gold particles trapped in the ridges.
Larger placer operations use large tools for excavation including bucket wheel excavators, powers shovels, draglines, and conveyors. Dredges are large pieces of equipment that devour tons of earth quickly in search of the gold.
For dredges to be effective, a lot of money is initially spent for prospecting and testing the ground to determine the location and size of the gold. Usually companies will use extensive drilling programs to determine where the largest accumulations of gold are. Dredges are capable of being used to great depths, however if the gold is less than 2 feet deep they are often not effective because the gravel doesn’t stay in the buckets long enough to reach the hopper.
Hydraulic mining uses high pressure water which sprays an area of rock. The pressure of the water helps to break the rock up and dislodge any placer or ore deposits. The mix is then milled. Hydraulic mining is used infrequently these days because it is very destructive so it has been outlawed in most places.
Hard rock mining involves digging into solid rock to find the minerals which are normally in their ore form. Dynamite, picks, shovels, drills, and a host of other equipment is used to reach the ore. Often mine shafts are dug that are made up of miles and miles of tunnels which follow the veins of the ore.
Shafts will have a head frame that stands above them which supports the hoists. Tunnels and chambers are supported with large timbers which stop any cave ins from occurring.
Because the cost of exploration is so high and the removal of the gold using hard rock mining extremely expensive, companies have to raise a lot of money for the development of the mine. Hard rock mining is never a venture taken on by an individual or small company. Hard rock mining is a “big boys” game.
Open pit mining involves digging really big holes in the ground and is often used for minerals like copper or coal. The size of these mines is absolutely devastating to the surrounding area. To expose the ore it is necessary to excavate and move huge quantities of waste rock. Companies attempt to do this for the lowest price possible to help maximize their profits.
Open pit mining really does become an economic exercise that is decided by mining and geologic aspects. Because of the environmental impact this type of mining is not done very often anymore.
Mining operations are an important part of our economy providing many jobs and playing an important role in our GDP. The type of mining operation will depend on the mineral, the location, and the quantity being mined.