The incredible story of 33 miners trapped in a copper mine for a record 69 days captivated people around the world in late summer 2010. The rescue attempts that ensued made use of cutting edge technology, as well as sound engineering judgement. The Faculty of Science hosted a talk about the mine on Tuesday, February 15, titled Disaster and Deliverance, with Maurice Dusseault and Steve Evans present to discuss the mine collapse as well as the techniques used to rescue all 33 miners successfully. Both Maurice Dusseault, P.Eng, and Steve Evans are professors in the Department of Earth and Environmental Sciences, and are experienced in the field of geological engineering.
The mine collapse occurred at the San Jose copper-gold mine in the Atacama Desert, located near Copiapo, Chile. The collapse itself occurred on August 5, 2010, though the safety concerns that led up to the accident started before that. The country of Chile produces approximately one third of the world’s copper, and also contains about one third of the remaining stores of copper left to be extracted. As a result, mining is one of the largest industries in the country, with some mines run to very high standards and others to much lower. The San Jose mine fell into the second category, having been shut down in 2007 due to safety concerns and litigations, but was reopened in 2008 despite failing many safety regulations.
The initial collapse destroyed part of the spiral shaft leading down into the mine, preventing the escape of the miners. Subsequent movements during rescue attempts caused further collapses in the main access route. The miners found refuge in a secure room, organizing their food for long term survival. On the surface, numerous boreholes were drilled in record time. Modern technology allowed for precise aiming of the boreholes; as a result, rescuers were able to drill holes to areas throughout the mine where the miners were likely to be. After reaching an air pocket, a bore was withdrawn with a note from the miners attached telling rescuers that all 33 were still alive. While this initial bore hole, only about 16 centimeters in diameter, was used to provide food and entertainment for the miners, three new holes were bored to implement three concurrent rescue attempts.
Plan A utilized a raise borer type rig, which is normally used to drill upwards from one mine shaft to another. The drill was modified to be anchored to the ground to allow for downward drilling. Plan B utilized a percussion hammer drill, with a brand new configuration that allowed for much faster drilling through the process of crushing the rock through impact rather than trying to gouge away like a regular drill bit. Plan C utilized a Canadian built oil drilling rig, using a liquid slurry to collect cuttings.
Plan C was the one that eventually reached the miners first on October 9, requiring some help from the miners themselves. The drill used a number of stages to gradually widen the hole. During this process, all the cuttings fell down the hole and were removed by the trapped miners using equipment left in the mine with them. Some believe that this continual work helped keep the miners motivated, rather than just sitting and waiting for the whole time.
During the drilling process the rescue capsule, known as Phoenix, was being designed and constructed by the Chilean Navy and NASA. The capsule had to fit within the 66 centimeter (26in) diameter hole, while protecting each miner as they were carried up through the rough hole. On board oxygen, communication systems, as well as guiding wheels allowed the miners to ride up the shaft equipped for emergencies, and hopefully preventing impacts against the shaft walls. The rescue operation started on October 12, with several rescuers descending into the refuge area to assist the miners escape. Over a period of almost 24 hours all 33 miners were brought to the surface, to be greeted by their families. Some were immediately treated for medical conditions as well as dental infections.
One point that was stressed by Professor Dusseault was the honor present in the mining industry, and the call to help whenever an accident occurs. Many people believe that the miners were able to survive for as long as they did because they firmly believed that they would be rescued. They knew that their fellow miners would be searching for them and would do everything possible to help them. Much of the equipment used in the rescue was offered freely – if you expect others to come to your rescue then you better be ready to offer your help to rescue them.
The Chilean mining accident had the capacity to become a national disaster, but it was instead turned into a successful rescue operation. All 33 miners were safely brought to the surface, through human perseverance and technological innovation.
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