At least 18 people have been reported dead after a mine collapse in Pakistan.
The failure occurred on Monday, September 8, 2020, in a remote mine situated in Pakistan's Khyber-Pakhtunkhwa province.
The quarry is known for its white marble production which is sold in Pakistan and abroad. According to local sources, the marble was extracted using explosives and a rockslide was triggered.
Several workers were impacted by falling debris as 40 to 50 people were at the scene. “Usually a large number of people work in these marble mines but luckily a majority had finished work and returned home,” Tariq Habib, district police chief of Mohmand district, stated. Currently, 18 people are considered dead, 7 were injured and many are still missing.
According to the local police department, the collapse blocked the entrance of the mine making it extremely challenging for rescuers to search for survivors. As of Tuesday, September 9, rescue operations were still ongoing.
Drilling and Blasting Method
Mining is the world's largest industry when it comes to civil explosives usage. The majority of rocks are strong and cannot be broken down by mechanical means. Therefore, engineers use explosives that detonate in order to produce shocks that can break the rock in segments.
Those explosives are placed into certain holes that are drilled through the rock mass and are activated according to certain safety protocols so that no person involved is in danger. The drilling process is conducted with rotary equipment to create hols that propagate through the rock.
ANFO (Ammonium Nitrate Fuel Oil) is one of the most utilized explosives worldwide as it is safe to store and transport while its production is relatively inexpensive.
Today, blasts are initiated via shock tubes which are very accurate, non-electric detonators that provide extra safety. The holes are drilled in selected positions and with certain planning so that: a) a specified volume of rock within certain boundaries is excavated, b) acceptable sizes of broken rock fragments are achieved and c) extreme debris scattering is prevented. In fact, perfect explosive procedures aim at gathering all the material in one place.
The detonations have to be well-coordinated so that shock waves are produced in a certain sequence that will break the rock as described above.
In the Media section below, you can watch a video on the underground drilling and blasting technique.
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