Mine Tales: Underground mines overcome daunting challenges | Local News


Miners employed by the United Verde Copper Co. in Jerome pose with their candlesticks around 1900.

Courtesy of Freeport-McMoRan Copper & Gold Inc.

William Ascarza Special for the Arizona Daily Star

Underground mining operations faced development challenges including drainage, ventilation, lighting and excavation support.

Groundwater comes from the surface, often through porous or fissured rock masses, alluvial materials, sand, gravel and limestone. Meteoric water from rain, snow, and fog, connate water buried in rocks that contain it, and magmatic water from cooling magma and resulting rocks are some classifications defining water sources.

Mines across Arizona have met the challenges of stope dewatering with aggressive pumping systems.

The Magma Mine built a 1,200 gallon per minute pumping station at the 3,600 foot level early on. The Old Dominion mine used deep shaft turbines to drill holes removing water from mine levels as a prerequisite for further development. Tombstone Mines used heavy Cornish pumps to alleviate flooding in the 1880s and 20 years later built two 1,500 gallon per minute pumps at the 700 foot station to handle over 2 million gallons of water per day.

Water acidity challenges in copper mines include corrosion of mining equipment such as fittings, pipes, pumps and valves. Solutions including the use of lime as an acidic water neutralizing agent were used in the early 1900s. However, when mixed in a stirred tank and added to slurry in varying amounts, the compound of lime was accumulating on ditches and cesspools.


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