ASME-Landmark:Magma Copper Mine Air Conditioning System

The Magma Copper Company Mine was notoriously hot, with a temperature increase of approximately 1½°F per 100 feet of depth and a rock temperature on the 2000-foot level of 109°F. At the time, the practice for cooling the mine had been to open up a level and let it stand for several years to cool off with ventilating fans; the 3200-foot level required about three years of cooling before it could be developed with any degree of efficiency. In early 1935, a crosscut on the 4000-foot level revealed a rock temperature of 140°F—and an evident need for artificial means of cooling and air conditioning the lower levels of the mine.

The first refrigerating units had been built by Willis H. Carrier in South Africa and then Brazil some years earlier. The Magma Copper Mine became the first refrigerated mine in North America on July 19, 1937, when the first unit was installed. Several centrifugal refrigeration machines of 140-ton capacities were lowered through shaft compartments and set to work, lowering the temperature in six weeks to better conditions than could be achieved with traditional ventilating fans after three years.

The air conditioners vastly improved health and safety factors in mine operations and made deeper excavation possible. After the Magma Copper Mine was mined out, the two original units were abandoned and remain in the mine. See ASME website for more information