Gold cyanidation is a hydrometallurgical technique for extracting gold from low-grade ore by converting the gold to a water-soluble coordination complex. It is the most commonly used leaching process for gold extraction. Cyanidation is also widely used in the extraction of silver, usually after froth flotation.
Yellowcake is a type of uranium concentrate powder obtained from leach solutions, in an intermediate step in the processing of uranium ores. It is a step in the processing of uranium after it has been mined but before fuel fabrication or uranium enrichment. Yellowcake concentrates are prepared by various extraction and refining methods, depending on the types of ores. Typically, yellowcakes are obtained through the milling and chemical processing of uranium ore, forming a coarse powder that has a pungent odor, is insoluble in water, and contains about 80% uranium oxide, which melts at approximately 2880 °C.
An ion-exchange resin or ion-exchange polymer is a resin or polymer that acts as a medium for ion exchange. It is an insoluble matrix normally in the form of small microbeads, usually white or yellowish, fabricated from an organic polymer substrate. The beads are typically porous, providing a large surface area on and inside them where the trapping of ions occurs along with the accompanying release of other ions, and thus the process is called ion exchange. There are multiple types of ion-exchange resin. Most commercial resins are made of polystyrene sulfonate, followed up by polyacrylate.
Hydrometallurgy is a technique within the field of extractive metallurgy, the obtaining of metals from their ores. Hydrometallurgy involve the use of aqueous solutions for the recovery of metals from ores, concentrates, and recycled or residual materials. Processing techniques that complement hydrometallurgy are pyrometallurgy, vapour metallurgy, and molten salt electrometallurgy. Hydrometallurgy is typically divided into three general areas:
Uranium(IV) sulfate (U(SO4)2) is a water-soluble salt of uranium. It is a very toxic compound. Uranium sulfate minerals commonly are widespread around uranium bearing mine sites, where they usually form during the evaporation of acid sulfate-rich mine tailings which have been leached by oxygen-bearing waters. Uranium sulfate is a transitional compound in the production of uranium hexafluoride. It was also used to fuel aqueous homogeneous reactors.
Heap leaching is an industrial mining process used to extract precious metals, copper, uranium, and other compounds from ore using a series of chemical reactions that absorb specific minerals and re-separate them after their division from other earth materials. Similar to in situ mining, heap leach mining differs in that it places ore on a liner, then adds the chemicals via drip systems to the ore, whereas in situ mining lacks these liners and pulls pregnant solution up to obtain the minerals. Heap leaching is widely used in modern large-scale mining operations as it produces the desired concentrates at a lower cost compared to conventional processing methods such as flotation, agitation, and vat leaching.
Uranium mining is the process of extraction of uranium ore from the ground. Over 50 thousand tons of uranium were produced in 2019. Kazakhstan, Canada, and Australia were the top three uranium producers, respectively, and together account for 68% of world production. Other countries producing more than 1,000 tons per year included Namibia, Niger, Russia, Uzbekistan, the United States, and China. Nearly all of the world's mined uranium is used to power nuclear power plants. Historically uranium was also used in applications such as uranium glass or ferrouranium but those applications have declined due to the radioactivity of uranium and are nowadays mostly supplied with a plentiful cheap supply of depleted uranium which is also used in uranium ammunition. In addition to being cheaper, depleted uranium is also less radioactive due to a lower content of short-lived 234
U and 235
U than natural uranium.
National Atomic Company Kazatomprom Joint Stock Company (Kazatomprom) (Kazakh: Қазатомөнеркәсіп, romanized: Qazatomónerkásip) is the world’s largest producer and seller of natural uranium, providing over 40% of global primary uranium supply in 2019 from its operations in Kazakhstan. Kazatomprom's uranium is used for the generation of nuclear power around the world.
Uranium mining in the United States produced 173,875 pounds (78.9 tonnes) of U3O8 in 2019, 88% lower than the 2018 production of 1,447,945 pounds (656.8 tonnes) of U3O8 and the lowest US annual production since 1948. The 2019 production represents 0.3% of the anticipated uranium fuel requirements of the US's nuclear power reactors for the year.
Uranium mining in Colorado, United States, goes back to 1872, when pitchblende ore was taken from gold mines near Central City, Colorado. The Colorado uranium industry has seen booms and busts, but continues to this day. Not counting byproduct uranium from phosphate, Colorado is considered to have the third largest uranium reserves of any US state, behind Wyoming and New Mexico.
Uranium mining in Wyoming was formerly a much larger industry than it is today. Wyoming once had many operating uranium mines, and still has the largest known uranium ore reserves of any state in the U.S. At the end of 2008, the state had estimated reserves dependent on price: 539 million pounds of uranium oxide at $50 per pound, and 1,227 million pounds at $100 per pound.
Uranium ore deposits are economically recoverable concentrations of uranium within the Earth's crust. Uranium is one of the most common elements in the Earth's crust, being 40 times more common than silver and 500 times more common than gold. It can be found almost everywhere in rock, soil, rivers, and oceans. The challenge for commercial uranium extraction is to find those areas where the concentrations are adequate to form an economically viable deposit. The primary use for uranium obtained from mining is in fuel for nuclear reactors.
Crow Butte is a uranium mining operation located four miles (6 km) southeast of the city of Crawford in Dawes County, Nebraska, United States. Cameco Corporation owns and operates Crow Butte through its wholly owned subsidiary, Crow Butte Resources, Inc.
Four Mile is Australia's fifth uranium mine. It is sited in the Frome Basin in far north of the state of South Australia, around 600 kilometres (370 mi) north of the state capital, Adelaide. It is 10 kilometres (6 mi) from the existing Beverley uranium mine, where its uranium oxide product is produced. Construction of the mine commenced in late 2013 and the mine was officially opened in June 2014.
Namibia has one of the richest uranium mineral reserves in the world. There are currently two large operating mines in the Erongo Region and various exploration projects planned to advance to production in the next few years.
The world's largest producer of uranium is Kazakhstan, which in 2019 produced 43% of the world's mining output. Canada was the next largest producer with a 13% share, followed by Australia with 12%. Uranium has been mined in every continent except Antarctica.
The Willow Creek mine is an in-situ leach (ISL) uranium mining project located in Powder River Basin in the state of Wyoming, United States. It comprises the Irigaray central processing plant and wellfields, and the Christensen Ranch ion exchange plant and wellfields.
The Imouraren mine is a large mine located in the northern part of Niger in Agadez Region, about 80 km (50 mi) south of Arlit. Imouraren represents one of the largest uranium reserves in Niger having estimated reserves of 109.1 million tonnes of ore grading 0.06% uranium. It is the site of a uranium mining project involving French company Areva and SOPaMin. The U3O8 ore grade at nearby SOMAIR is 14,000 tons at 0.3%, COMINAK is 29,000 t at 0.4% and Imouraren 120,000t at 0.15%.
Uranium acid mine drainage refers to acidic water released from a uranium mining site using processes like underground mining and in-situ leaching. Underground, the ores are not as reactive due to isolation from atmospheric oxygen and water. When uranium ores are mined, the ores are crushed into a powdery substance, thus increasing surface area to easily extract uranium. The ores, along with nearby rocks, may also contain sulfides. Once exposed to the atmosphere, the powdered tailings react with atmospheric oxygen and water. After uranium extraction, sulfide minerals in uranium tailings facilitates the release of uranium radionuclides into the environment, which can undergo further radioactive decay while lowering the pH of a solution.
Greyhawk Mine is a decommissioned underground uranium mine located in Faraday Township near Bancroft, Ontario. It operated from 1954 to 1959 and from 1976 to 1982. The mine produced 80,247 tons of uranium ore, of which 0.069% was U3O8 worth $834,899.
