Source of information: http://www.brokrew.co.za/index.php?page=mining_ventilation
Mining is a dangerous industry. Every day of their lives miners take incredible risks to pull valuable ores and minerals from the crust of the earth. To keep these brave souls safe deep beneath the earth, adequate mining ventilation is required to ensure that they are supplied with fresh, clean air. Combining massive ventilation shafts and kilometres of ducting, mining ventilation is a specialised area of the mining industry where there is no room for mistakes.
Mining ventilation is primarily there to provide oxygen to the miners and to dilute and remove dangerous and volatile gasses and dust. Mining produces a host of dangerous gasses like NO2, SO2, CO2, CO and methane that can poison the miners or replace the oxygen in the air slowly asphyxiating miners working deep underground. Other gasses like methane and coal dust are highly explosive needing only a tiny spark to set of a cataclysmic explosion that could bring down an entire tunnel in seconds. Mining ventilation helps to keep these dangers to a minimum.
Mining ventilation is based on keeping a stream of air circulating through the mine. This is done by maintaining a pressure difference between the inside of the mine and the surface with large fans. Stale, dirty air and gasses are expelled from the mine using massive extraction fans. The resulting vacuum sucks in fresh air from the surface, aided by more fans, to clean and dilute the air inside the mine.
There are two types of mining ventilation that is commonly used in most mines. The main type is known as flow-through ventilation. This is the main circuit of air that travels through the mine. It enters a large ventilation shaft and travels throughout the mine before leaving by another ventilation shaft. The air is moved and controlled by a series of fans and regulators that ensure the air keeps moving.
To get the fresh air to where the miners are, the second type of mining ventilation is used: auxiliary ventilation. This ventilation system takes air from the main circuit and directs it to where the miners are. Fans, ducting and special ventilation shafts are used to transport the air to where it is most needed and out again. These two mining ventilation streams work together and keeping the balance between the two is a full-time job for the ventilation engineers of the mine.
For mines located in inhospitable areas like the arctic or some of the bigger deserts, mining ventilation plays an additional role. Man and machine cannot work under all extreme conditions. Mining ventilation can warm or cool down the air that enters the mine to make the conditions more favourable to both the miners and their equipment. Some mines in the arctic actively keep the air cold in the mine to ensure that the permafrost does not melt due to the mining activities taking place in the area.
With massive ventilation shafts, kilometres of ducting and an array of fans both big and small, mining ventilation ensures that miners get the fresh air they need to keep doing their job underground.