New Delhi: Rat hole mining is a banned mining technique. It was outlawed by the National Green Tribunal (NGT) due to its serious environmental impacts and lack of safety for labourers.
But this outlawed rat hole mining technique was used to rescue the 41 construction workers trapped inside a collapsed Uttarakhand tunnel. This banned technique became successful where modern machinery failed.
Rat-hole mining is commonly reported in Meghalaya. Despite being banned in 2014, it still continues illegally in secret in some parts of Meghalaya.
In rat hole mining, holes are drilled to extract small quantities of coal. At times five to 100 square metres are dug to reach the coal seams.
This technique allows a single miner to go inside a narrow to extract the coal. As the tunnel fits a single miner, they are called rat holes.
The American auger machine drilled roughly 47-48 meters of a horizontal tunnel. After that, it broke down beyond repair. At that time, the help of rat hole mining experts was sought, who completed the remaining task in less than two days.
The rat hole miners went inside the steel pipe being pushed inside the rubble through which trapped workers will be pulled out and drilled a horizontal passage. The process was somewhat similar to the digging of a narrow tunnel for coal mining.