Mine Ventilation
Mine ventilation has always been essential to creating underground conditions in which miners can work.
In addition to supplying the necessary oxygen for miners to breathe, ventilation must maintain adequate temperature and humidity and must carry away the dust and gases created during blasting. Mines were wet, so evaporation increased humidity underground. The deeper a mine gets, the closer it is to the center of the Earth, so temperatures rise. In addition, rotting mine timbers and the oxidation of sulfide minerals generated heat and raised the air temperature in Butte’s underground workings. Using more electrical equipment underground also increased the heat generated. Finally, on-going underground mine fires contributed heat within some areas of the Butte Hill. An 1889 fire in the St. Lawrence mine, for example, continued burning for at least three decades.
Prior to 1910, mines in Butte relied on what they called natural ventilation, which could be enhanced if adjoining shafts were connected by means of their underground workings. Such connections would allow a shaft that was lower on the hill to function as a downcast shaft, supplying fresh air to the workings, and a shaft higher on the hill would be an upcast shaft, allowing warm air from the workings to rise through the shaft. Another source of ventilation was the compressed air released underground during the operation of rock drills.
In 1910, after most of the big mines on the Butte Hill were consolidated under the ownership and operation of Anaconda Copper Mining Company (ACM), the company converted several mines from being shafts hoisting ore to serving as ventilation shafts by installing giant fans to draw large volumes of air from the underground workings, which were connected to the workings of nearby mines. That meant the remaining producing shafts became downcast shafts by means of the artificial ventilation. Among mines that were converted to ventilation shafts by February 1911 were the Corra, Gambetta, Parnell, and East Steward.
By 1920, ACM had consolidated even more mining companies in Butte, and it operated 28 mines on the Butte Hill. ACM had also adopted the method of using canvas pipe and fans underground to convey fresh air to the ends of mine workings.
Around 1950, as ACM was increasing zinc production from the Anselmo mine, it decided to enhance ventilation of the Anselmo’s underground workings by driving a shaft on the Volunteer mining claim near the BA&P tracks and 1,600 feet to the southwest of the Anselmo shaft. Miners connected the new shaft underground to the 800 level of the Anselmo shaft. Workers on the project called it the Desperation shaft because of the problems they encountered with water. The concrete fan housing atop the Desperation shaft survives and is the last surviving structure of its kind in Butte.
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