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

 Courtesy of Freeport-McMoRan Copper & Gold Inc.

Underground mining operations have had to deal with development challenges including drainage, ventilation, illumination and excavation support.

Water underground originates from the surface, oftentimes through porous or fissured rock masses, alluvial material, sand, gravel and limestone. Meteoric water from rain, snow and fog, connate water buried with rocks that contain it, and magmatic water originating from cooling magma and resulting rocks are some classifications defining water sources.

Mines throughout Arizona have met the challenges of dewatering workings through aggressive pumping systems.

The Magma Mine early on built a 1,200-gallon-per-minute pumping station at the 3,600-foot level. The Old Dominion Mine used deep-well turbines to bore holes removing water from the mine levels as a prerequisite to further development. The mines at Tombstone employed heavy Cornish pumps to mitigate flooding in the 1880s and 20 years later built two 1,500-gallon-per minute pumps at the 700-foot station to handle more than 2 million gallons of water daily.

Challenges involving water acidity in copper mines include corrosion of mining equipment such as fittings, pipes, pumps and valves. Solutions including the use of lime as a neutralizing agent of acid water were used in the early 1900s. However, when mixed in an agitating tank and added to slurry in varying amounts, the lime compound would accumulate on the ditches and sumps.

Harrison M. Lavender was a renowned Phelps Dodge vice president in charge of Western Operations and the namesake of the Bisbee open pit mine development known as the Lavender Pit. He was successful in processing acid copper-bearing mine water that replaced lime mineralization. Mine water was passed through a series of 10-foot-long by 5-foot-wide and 5-foot-high water-proofed concrete boxes filled with scrap iron, which precipitated the copper while neutralizing the water acidity.

Ventilation, another challenge to successful underground mining operations, involved the need to manage accumulation of gases in workings including those of carbon monoxide, methane, hydrogen and nitrogen. These gases occur naturally in most rocks; however, in high concentrations, these can prove fatal to miners.

Firedamp, a combustible gas comprised of methane, is often found in coal mines. Blackdamp, a mixture of around 90% nitrogen and 15% carbon dioxide, is caused by combustible gases. Heavier than air, it is often found on the surface of a mine, reducing the oxygen content in the air and leading to the asphyxiation of miners in proximity.

Oftentimes mice or small birds were taken underground to measure levels of carbon monoxide due to their sensitivities to gases, hence the phrase “canary in a coal mine.” This practice was later replaced by electronic detectors.

Some early examples of mine ventilation in Arizona involved the Oatman district at the Tom Reed gold mine. Work at the 1,100 level in 1931 proved challenging with temperatures in excess of 103 degrees. Procurement of a No. 8 Sirocco fan driven by a 25-horsepower motor, delivering 31,000 cubic feet of air per minute, was installed at the bottom of the United Eastern shaft on the 950 level. A system of wooden control doors was also installed to moderate the air flow. Better air distribution, cooler temperatures resulting from the absorption of heat from exposed surfaces, and reduction of relative humidity resulted in improved working conditions.

Another example involved the 4,600-foot-deep Magma Mine installing an air-conditioning plant that required 494,310 kilowatt-hours for its monthly operation in November 1937. The refrigerating units were placed underground, relying on underground water source for cooling and pumps for circulating.

Other methods of ventilation included dust mitigation with bag filtering units and spray chambers around loading chutes, transfers and underground crushers. Today, small portable devices including anemometers and airflow meters use wind velocity as a means to test air quality and determine airflow in a mine, reducing the buildup of deadly gases.

Innovations in mine illumination have evolved from candles, oil and carbide lamps to the electric cap lamp consisting of a lamp attached to a miner’s cap connected by a flexible cord that draws current from a small storage battery attached to the miner’s belt. Battery power lasted 12 hours and was recharged after the miner’s shift. Permissible electric mine lamps included a safety feature that would prevent ignition of explosive methane and air mixtures in the event that the lamp bulb was broken.

Underground drilling with shaft cribbing seen at right.

A history of mine disasters in the United States in the early 20th century (25 alone in 1910), preceded by the 1907 Monongah Coal Mine disaster in West Virginia (considered the largest coal mine disaster in U.S. history with a documented 362 casualties), prompted congressional action.

The U.S. Bureau of Mines was established in an attempt to improve working conditions in mining operations across the country.

The Mine Safety Appliances Co. was tasked to create an improved and safer electric cap lamp. Thomas Edison was credited with having designed the Edison Cap Lamp, comprised of a rechargeable battery pack in a self-locking steel case. It included the safety feature of an electrical contact disconnect should the bulb break, enabling the tungsten filament to cool, so as to avoid igniting flammable gasses in the air.

Another safety concern involving underground mining is rock support for excavations. Early methods employed including timber post and cross-members installation to avoid cave-ins induced when conducting blasting and seismic loading. Many types of materials are used as support structures in mines including timber, concrete, stone, steel, brick and cast iron.

Treated timber for longevity with coal-tar creosote or zinc chloride has proven effective in shafts, adits, stations, air ways and track lines. Principle systems involving timbering include cribs (appears as a log house structure), square-sets (trusses constructed on vertical and horizontal lines) and stulls (timber props wedged between two walls of a stope as a framework to prevent cave-ins).

No doubt, underground mining practices evolved over the 20th century to facilitate the safety needs of the miner and the production of the mine site.

Waste filling in cut & fill stope.

Permissible methane detector manufactured by the Mine Safety Appliances Co.

Permissible electric signal lamp issued to the Concordia Electric Co. by the CEAG Ltd.

A "Sirocco" fan wheel

Square-set timbering on an inclined ore-body.

Cribbing or log-house structure used for underground mining support.

Schematic showing automatic pump control for high-level sump used for mine water drainage.

Edison cap lamp

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A special thank you to local Tucsonan Bruce McDermaid, who provided the author with the mine safety lamps of which several images are displayed in this article.

William Ascarza is an archivist, historian and author of seven books available for purchase online and at select bookstores. These include his latest, “In Search of Fortunes: A Look at the History of Arizona Mining,” available through M.T. Publishing Co. His other books are “Chiricahua Mountains: History and Nature,” “Southeastern Arizona Mining Towns,” “Zenith on the Horizon: An Encyclopedic Look at the Tucson Mountains from A to Z,” “Tucson Mountains,” “Arizona-Sonora Desert Museum” with Peggy Larson and “Sentinel to the North: Exploring the Tortolita Mountains.” Email William Ascarza for a signed copy of his publications at AZMiningHistory@gmail.com