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Arizona Experience Store

Mining Arizona

Click on the interactive map for a closer look at Arizona’s active mine sites.

Arizona has led copper production in the U.S. since 1910 and still enjoys that distinction, producing approximately 64% of domestic copper. The first of Arizona’s “Five Cs,” copper is the state’s most valuable mineral commodity, comprising 75% of the value of Arizona’s total nonfuel mineral production.

In addition to copper, molybdenum, construction sand and gravel, portland cement, crushed stone, and lime contribute significantly to Arizona’s economy. These six commodities comprise 99% of the state’s total production value, worth $7.84 billion in 2008.

Over 350 quarries and aggregate plants produce industrial minerals and rock products such as, lime, construction sand and gravel, salt, and pumice and perlite.

In addition to metals, energy sources such as uranium and coal are mined on the Colorado Plateau

Metal Mining

Arizona’s metallic mineral districts have yielded gold, silver, copper, and base metals. Zoom in on the map to locate Arizona’s mineral wealth.

Copper mining and refining provides over 10,000 jobs in Arizona. According to the Arizona Mining Association, the combined direct and indirect impact of copper mining was worth up to $34.2 Billion in the U.S. economy and 12.1 billion in Arizona.

Many towns were built on mining claims from the 1880s to the 1920s, with mining companies like Arizona Central and Phelps Dodge investing in equipment, refinement facilities, and infrastructure to transport goods. Immigrants from all over the world found work in the mines. Labor disputes between miners and their company were common.  By the 1970s copper was running out.

Some early mine sites, such as Bisbee and Jerome, shrank to the brink of nonexistence when the mines closed but found new life as tourist havens. Former copper towns in central Arizona have formed the Copper Corridor, a movement to attract tourism due to their mining history. Others, like Morenci and Bagdad, still significantly contribute to Arizona’s gross exports. The Morenci open pit complex is the largest copper mine in North America and the largest employer in Greenlee County. Additional copper-rich areas have been identified as potential future mine sites.

Copper cathodes are lined up for distribution from the San Manuel smelter, which was demolished in 2007.

Copper Facts

  • Copper is an excellent electrical conductor. Copper wiring made widespread use of electricity possible in the early 1900s.
  • Copper transformed and modernized households in the 1920s and 1930s with piping and wiring.
  • The average home contains about 400 pounds of copper for electrical wiring, pipes, and appliances such as refrigerators and microwaves.
  • Copper production bolstered wartime efforts with specially made equipment in World Wars I and II.
  • Copper is required for semiconductors, cell phones, computer chips, and other advanced technology.
  • Nearly one half of the copper consumed annually in North America comes from recycled material.

Arizona is the second-largest producer of molybdenum, which is extracted as a byproduct of copper in the Sierrita, Mission, Mineral Park, and Bagdad mines. Used primarily in the steel industry for corrosion resistance, strengthening and heat resistance, molybdenum (moly) chemicals and powder products can be used in water treatment, lubricants, and petroleum refining. New mining techniques are able to extract gold ore from mines in western Arizona.

Silver and Gold

Mojave Desert Minerals reopened the Gold Road goldmine in Oatman in 2007.

Gold and silver play a significant role in Arizona’s mining history. In the 1850s–1860s, prospectors placer mined gold from rivers in central Arizona. New technology has unlocked previously unaccessible ore, and two gold mines have opened in the past decade.

The Cochise County town of Tombstone was founded near a silver deposit that produced $13 million of the precious metal, and silver was found in Globe and Superior. Arizona’s name is thought to come from Arizonac, a silver mine southeast of Nogales that produced large silver nuggets, some weighing over a ton. Today, Arizona is fifth in the nation for the production of silver, mined mostly as a byproduct from copper processing.

 

Ore Refinement

Any metal-bearing rock is known as ore. The feasibility of a mine is determined in part by ore grade. In the early 1900s, 30% pure ore (600 pounds of copper per ton) was the average copper content. By the 1930s, ore purity (concentration) had fallen to approximately 4%. Newer mining technologies were developed to process ore with low mineral content, and today it is common to mine ore with a purity of just .35%—only 7 pounds of metal per ton!

Extraction techniques have changed from underground methods to “open pit” mining that can process larger volumes of raw material refined on site. Industry and mining comprises about 5% of Arizona’s total water use (approximately 386,600 acre-feet, or 126 billion gallons per year). In 2010, fresh water consumption at a concentrator plant was around 200 gallons per ton of ore.

Copper minerals generally occur as oxides or sulfides. Copper sulfides are crushed, ground, floated and the resultant concentrates are transported to smelters for refining into anodes.  Today most copper oxides are liberated by solvent extraction. Ore is exposed to acid in a heap leach to liberate the copper ions. Sulfuric acid is commonly used to extract copper; cyanide solution is often used for gold. The metal dissolves and binds to the liquid, which seeps onto a plastic–lined catchment pool and is directed to the solvent extraction process, followed by the electrowinning of the copper to form copper cathodes.

 

We are pleased to recognize the Freeport-McMoRan Copper & Gold Foundation as the presenting sponsor of the Virtual Arizona Experience.


Placer Mining

Placer Mining – Extracting heavy minerals such as gold or gemstones from unconsolidated alluvial sediments, i.e., sands and gravel.  Common small-scale placer mining involves panning or a sluice box. Many solitary prospectors who made their way to California and Arizona in the mid- 1800s were placer miners.  This image shows placer mining for gold in Yavapai County.

Open Pit Mining

Open Pit Mining – Common in the U.S., open pit mining involves removing ore (copper, gold, silver, uranium) and overburden, the valueless rock that overlies the ore. The open pit is wider at the top than at the bottom and the pit wall contains steps or benches that prevent rock from landsliding or falling to the bottom. Open pit mining is commonly used to in the porphyry copper mines of Arizona – e.g., the Lavender Pit near Bisbee and the Ray Mine near Superior (pictured here).

Strip Mining

Strip Mining – Coal of the Kayenta Mine on Black Mesa on the Navajo Nation is extracted via strip mining, where a seam of coal is extracted after first removing the overlying layer of soil and rock. Earth movers and dragline excavators are used to extract the mineral. Strip mining is not common in Arizona.

Quarry Mining

Quarry Mining– An open-pit mine where the mineral or rock extracted is commonly used in the building or aggregate industry.   Some of the more common Earth materials quarried in Arizona include: sand and gravel, limestone, flagstone, cinders and granite. These materials are not refined like ores, but can be crushed or otherwise processed. All these materials are very heavy, making them difficult to transport. Hundreds of quarries exist in Arizona to make raw material easily available for processing facilities.

Tabular Deposits (Room and Pillar Mining)

Tabular Deposits (Room and Pillar Mining)— Some minerals form over a continuous area in a stratified bed. These bodies can resemble a tabletop, and are known as tabular deposits. Tabular deposits such as salt or coal are mined using the “room and pillar” approach, where pillars of the material are left in to support the structure of the mine. Towards the end of the mine’s life, the pillars are harvested for their mineral content, ultimately leading to roof collapse.

Block Caving

Block Caving—This new form of extraction involves mining low-grade ore bodies from below the ore body.  The ore rock is delivered through “drawbells” from above to the haulage level. From there the rock is delivered to the processing plant for ore extraction. Large masses of rock are removed, resulting in a void that leads to collapse and subsidence of the ground above. The Resolution Copper Mine, planned for the Superior area, will involve block caving at almost 7000 feet below the ground surface.

Solution Mining

Solution Mining – Mining soluble materials, such as rock salt, potash, and even copper, can be done by introducing a solution through boreholes drilled into the mineral deposit. In the case of rock salt or potash, the solution may simply be water. Solution mining of copper relies on a weak sulfuric or hydrochloric acid to dissolve the copper. The mineral-rich solution is then pumped out of the deposit to surface ponds, where the ore mineral is extracted from solution. Following open pit extraction of ore, the ore is crushed and transported to a leach pad where it is irrigated with a leach solution to dissolve the metal. This image shows surface pools where dissolved copper is extracted from the solution. There are plans underway to use solution mining to extract copper from copper porphyry near Florence.