Digging deeper to extract products from the ground is a kind of art. There are different methods applied for digging. The three main methods are- underwater, open-pit, and underground mining. Underwater mining is required when the products are situated in an aquatic environment. Open-pit mining is necessary to extract the products that are located closer to the earth’s surface. And to extract the ore or products from below the surface, underground mining is used. The process used to extract ore is done economically and safely so that as little as possible goes to waste.
If you are interested in underground mining, read on to know more about it.
Also Read : An Overview of Supply Chain Management
Underground mining is necessary when the ore is too deep to dig out using an open-pit. When the quality and grades of the ore are economically high to cover costs, this method is used. It is practical if it has a footprint of lower ground than open-pit mining. The main equipment used for underground mining are a Caterpillar wheel dozer, Komastu excavator, Sandvik roof bolter, Hitachi dump truck, Caterpillar continuous miner, Hitachi feeder breaker. Some top jumbo drills used in underground mining are Sandvik drill rig, Hitachi drill, etc.
Hard-Rock Underground Mining
Hard-rock underground mining is required to excavate hard minerals containing metals. It refers to different techniques used for excavating minerals like lead, tin, nickel, zinc, copper, iron, silver, and gold. It is also used to excavate ores of gems like rubies or diamonds. Some methods of hard-rock underground mining are:
Cut and Fill
It is a short-hole mining method, used in ore zones that are irregular or steeply dipping. The ore is dug out in slightly inclined slices or horizontally. And then it is filled with sand, waste rock, or tailing. This method is a selective and expensive one. It has the advantages of low ore dilution and loss.
Drift and Fill
It is used for mining in the ore zones that are wide enough to allow drifting-method. In this method, the first drift is advanced in the ore, and then using consolidated fill, it is backfilled. Next, the second drift is induced., and is continued until the full-width ore zone is excavated.
It is suitable for the orebodies that are dipped steeply. It is similar to cut and fill mining. The broken ore left behind from blasting is used as a platform to work from, by supporting the surrounding rock. The next slice is drilled and blasted after removing enough ore from the stope. The ore is excavated slowly, resulting in a delayed return of the investment made in this method.
Vertical retreat mining (VRM) is a selective mining method that is used to divide mines into vertical zones. It is also known as Vertical crater retreat (VCR). It divides the mines with a depth of about 50 meters. Open stopping, a bottom-up mining technique is used in this method.
It is one of the bulk mining methods. And is necessary to excavate steeply dipping orebodies that are graded low and have high friability. In this case, drilling a part of ore is required at the bottom of the selected deposit, after blasting the roof collapses under its weight With the help of gravity, the ore adjacent to the fracture structure is hauled out and excavated for processing.
Room and Pillar Mining
It is mostly done in gently dipping or flat bedding or bodies. To mine out the rooms, using a regular pattern, pillars are placed. The roof of the rooms needs to be collapsed to get the ore from the pillars. For this, the pillars are taken out to fill the stope. This is done from the farthest point of the stope-entrance.
Soft-Rock Underground Mining
Soft-rock underground mining is necessary to excavate potash, oil shale, coal, and other geological materials or minerals from sedimentary rocks. This method is used for mining relatively less hard materials. Methods that are generally used in soft-rock underground mining are:
In this method, a longwall machine cuts through the ore deposits and shaves off slices that are more than 600 feet long. The slices go into a conveyor that moves continuously and carries them to a haulage shaft. The haulage shaft lifts the products out of the mine. It can recover about 90 percent of the ore.
It is an older method that is used to mine using explosives like dynamite. It was helpful to break up the seam of the coal. Then the coals are gathered to load onto the conveyors or shuttle cars for removal.
It is the same technique used for hard rocks. By using this method, oil shale, salt, phosphate, potash, coal, and bedded uranium ores are excavated. It can recover about 50% of the ore.
Short-wall mining is a method that is generally used for coal mining. It is required when the ore deposits are comparatively narrow. It involves the usage of continuous mining that has moveable roof supports.
Dangers of Underground Mining
Underground mining can be dangerous if it is not managed properly. The most common hazards due to mining are listed below:
- Explosions: It is a potential threat that is seen in underground mining. Flammable gases and chemicals are always running through the pipes. It is important to check the ventilation system while working and use warning signs to make the workers careful.
- Cave-ins, rock falls, or collapses: Be aware of collapses while mining. It can be systematically planned or scheduled. An appropriate safety plan is needed and the workers should be trained properly to get the work done without any risk.
- Fire and noise: The workers should be trained well so that they can be prepared in case of fire. It is important to have correct hearing protection because of the loud equipment and work process to avoid any kind of threat.
- Other risks: Electrical hazards, dust exposure, vehicle hazards are some typical risks involved in mining works. Checking out all equipment is necessary before starting the work to avoid any threats.
Underground mining is an efficient way to excavate ores from the ground. It needs less human labor. It is a useful way to get the materials out of the surface. Just ensure that proper precautions are taken to avoid any kind of dangers and risks.