Mountain Pass rare earth mine

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Mountain Pass Rare Earth Mine
MolycorpMountainPass.jpg
The Mountain Pass mine surface facilities. The upper part of the open pit is seen in the background.
Location
USA California location map.svg
Schlaegel und Eisen nach DIN 21800.svg
Mountain Pass rare earth mine
Location in California
LocationMountain Pass, San Bernardino County
State California
CountryUnited States
Coordinates 35°28′43″N115°31′57″W / 35.47861°N 115.53250°W / 35.47861; -115.53250 Coordinates: 35°28′43″N115°31′57″W / 35.47861°N 115.53250°W / 35.47861; -115.53250
Production
Products Rare-earth elements
2011 satellite image of the Mountain Pass mine and vicinity. The mine and plant sit just north of Interstate 15. The bright green areas at left center are settling ponds for the mine's wastewater. Mountainpass 2011.jpg
2011 satellite image of the Mountain Pass mine and vicinity. The mine and plant sit just north of Interstate 15. The bright green areas at left center are settling ponds for the mine's wastewater.

The Mountain Pass Rare Earth Mine is an open-pit mine of rare-earth elements on the south flank of the Clark Mountain Range, just north of the unincorporated community of Mountain Pass, California, United States. The mine once supplied most of the world's rare-earth elements. Owned by MP Materials, it is the only rare earth mining and processing facility in the United States. [1]

Contents

Geology

The Mountain Pass deposit is in a 1.4 billion-year-old Precambrian carbonatite intruded into gneiss. It contains 8% to 12% rare-earth oxides, mostly contained in the mineral bastnäsite. [2] Gangue minerals include calcite, barite, and dolomite. It is regarded as a world-class rare-earth mineral deposit. The metals that can be extracted from it include: [3] cerium, lanthanum, neodymium, [4] and europium.

In 2008, remaining reserves using a 5% cutoff grade were estimated to exceed 20 million tons of ore that averages 8.9% rare-earth oxides. [5]

Ore processing

To process bastnäsite ore, it is finely ground and subjected to froth flotation to separate the bulk of the bastnäsite from the accompanying barite, calcite, and dolomite. Marketable products include each of the major intermediates of the ore dressing process: flotation concentrate, acid-washed flotation concentrate, calcined acid-washed bastnäsite, and finally a cerium concentrate, which was the insoluble residue left after the calcined bastnäsite had been leached with hydrochloric acid.

The lanthanides that dissolve as a result of the acid treatment are subjected to solvent extraction to capture the europium and purify the other individual components of the ore. A further product includes a lanthanide mix, depleted of much of the cerium, and essentially all of samarium and heavier lanthanides. The calcination of bastnäsite drives off the carbon dioxide content, leaving an oxide-fluoride, in which the cerium content oxidizes to the less-basic quadrivalent state. However, the high temperature of the calcination gives less-reactive oxide, and the use of hydrochloric acid, which can cause reduction of quadrivalent cerium, leads to an incomplete separation of cerium and the trivalent lanthanides.

History

The Mountain Pass mine dominated worldwide REE production from the 1960s to the 1980s (USGS). Rareearth production.svg
The Mountain Pass mine dominated worldwide REE production from the 1960s to the 1980s (USGS).

The Mountain Pass deposit was discovered in 1949 by a uranium prospector who noticed anomalously high radioactivity. The Molybdenum Corporation of America bought the mining claims, and began small-scale production in 1952.

Production expanded greatly in the 1960s, to supply demand for europium used in color television screens. Between 1965 and 1995, the mine supplied most of the worldwide rare-earth metals consumption. [5]

The Molybdenum Corporation of America changed its name to Molycorp in 1974. The corporation was acquired by Union Oil in 1977, which in turn became part of Chevron Corporation in 2005. [6]

In 1998, the mine's separation plant ceased production of refined rare earth compounds; it continued to produce bastnäsite concentrate. [7]

The mine closed in 2002, though processing of previously mined ore continued, in response to both environmental restrictions and competition from Chinese suppliers. [8]

In 2008, Chevron sold the mine to privately held Molycorp Minerals LLC, a company formed to revive the Mountain Pass mine. Molycorp announced plans to spend $500 million to reopen and expand the mine, and on July 29, 2010, it raised about $400 million through an initial public offering, selling 28,125,000 shares at $14 under the ticker symbol MCP on the New York Stock Exchange. [9]

In December 2010, Molycorp announced that it had secured all the environmental permits needed to build a new ore processing plant at the mine; construction would begin in January 2011, and was expected to be completed by the end of 2012. On August 27, 2012, the company announced that mining had restarted.

The processing plant was in full production on June 25, 2015, when Molycorp filed for Chapter 11 bankruptcy with outstanding bonds in the amount of $US 1.4 billion. The company's shares were removed from the NYSE.

In August 2015, it was reported that the mine was to be shut down.

On August 31, 2016, Molycorp Inc. emerged from bankruptcy as Neo Performance Materials, leaving behind the mine as Molycorp Minerals LLC in its own separate Chapter 11 bankruptcy. As of January 2016, its shares were traded OTC under the symbol MCPIQ.

Affiliates of two U.S. investment fund advisors, JHL Capital Group LLC and QVT Financial LP and Shenghe Resources Holding Co., a Chinese minority shareholder, acquired Mountain Pass in July 2017 with the goal of reviving America's rare earth industry. [10] The venture does business under the name MP Materials (mpmaterials.com). [11] MP Materials resumed mining and refining operations in January 2018. [12]

Environmental impact

In the 1980s, the company began piping wastewater up to 14 miles to evaporation ponds on or near Ivanpah Dry Lake, east of Interstate 15 near Nevada. This pipeline repeatedly ruptured during cleaning operations to remove mineral deposits called scale. The scale is radioactive because of the presence of thorium and radium, which occur naturally in the rare-earth ore. A federal investigation later found that some 60 spills—some unreported—occurred between 1984 and 1998, when the pipeline and chemical processing at the mine were shut down. [13] In all, about 600,000 gallons of radioactive and other hazardous waste flowed onto the desert floor, according to federal authorities. By the end of the 1990s, Unocal was served with a cleanup order and a San Bernardino County district attorney's lawsuit. The company paid more than $1.4 million in fines and settlements. After preparing a cleanup plan and completing an extensive environmental study, Unocal in 2004 won approval of a county permit that allowed the mine to operate for another 30 years. The mine also passed a key county inspection in 2007. [6]

Current activity

Since 2007, China has restricted exports of REEs and imposed export tariffs, both to conserve resources and to give preference to Chinese manufacturers. [14] In 2009, China supplied more than 96% of the world's REEs. Some outside China are concerned that because rare earths are essential to some high-tech, renewable-energy, and defense-related technologies, the world should not be so reliant on a single supplier country. [15] [16]

On September 22, 2010, China quietly enacted a ban on exports of rare earths to Japan, a move suspected to be in retaliation for the Japanese arrest of a Chinese trawler captain in a territorial dispute. Because Japan and China are the only current sources for rare-earth magnetic material used in the US, a permanent disruption of Chinese rare-earth supply to Japan would leave China as the sole source. Jeff Green, a rare-earth lobbyist, said, "We are going to be 100 percent reliant on the Chinese to make the components for the defense supply chain." [17] The House Committee on Science and Technology scheduled on September 23, 2010, the review of a detailed bill to subsidize the revival of the American rare-earths industry, including the reopening of the Mountain Pass mine. [18]

After China doubled import duties on rare earth concentrates to 25% as a result of the US-China trade war, MP Materials said, in May 2019, it will start its own processing operation in the United States by 2020. [19] According to Bloomberg, "China Has a Rare Earths Plan Ready to Go if Trade War Deepens". [20]

Related Research Articles

Europium Chemical element with atomic number 63

Europium is a chemical element with the symbol Eu and atomic number 63. Europium is the most reactive lanthanide by far, having to be stored under an inert fluid to protect it from atmospheric oxygen or moisture. Europium is also the softest lanthanide, as it can be dented with a fingernail and easily cut with a knife. When oxidation is removed a shiny-white metal is visible. Europium was isolated in 1901 and is named after the continent of Europe. Being a typical member of the lanthanide series, europium usually assumes the oxidation state +3, but the oxidation state +2 is also common. All europium compounds with oxidation state +2 are slightly reducing. Europium has no significant biological role and is relatively non-toxic compared to other heavy metals. Most applications of europium exploit the phosphorescence of europium compounds. Europium is one of the rarest of the rare earth elements on Earth.

Lanthanum Chemical element with atomic number 57

Lanthanum is a chemical element with the symbol La and atomic number 57. It is a soft, ductile, silvery-white metal that tarnishes slowly when exposed to air and is soft enough to be cut with a knife. It is the eponym of the lanthanide series, a group of 15 similar elements between lanthanum and lutetium in the periodic table, of which lanthanum is the first and the prototype. It is also sometimes considered the first element of the 6th-period transition metals, which would put it in group 3, although lutetium is sometimes placed in this position instead. Lanthanum is traditionally counted among the rare earth elements. The usual oxidation state is +3. Lanthanum has no biological role in humans but is essential to some bacteria. It is not particularly toxic to humans but does show some antimicrobial activity.

The lanthanide or lanthanoid series of chemical elements comprises the 15 metallic chemical elements with atomic numbers 57–71, from lanthanum through lutetium. These elements, along with the chemically similar elements scandium and yttrium, are often collectively known as the rare earth elements.

Ore rock with valuable metals, minerals and elements

Ore is natural rock or sediment that contains desirable minerals, typically metals, that can be extracted from it. Ore is extracted from the earth through mining and refined, often via smelting, to extract the valuable element or elements.

Terbium Chemical element with atomic number 65

Terbium is a chemical element with the symbol Tb and atomic number 65. It is a silvery-white, rare earth metal that is malleable, ductile, and soft enough to be cut with a knife. The ninth member of the lanthanide series, terbium is a fairly electropositive metal that reacts with water, evolving hydrogen gas. Terbium is never found in nature as a free element, but it is contained in many minerals, including cerite, gadolinite, monazite, xenotime, and euxenite.

Rare-earth element Any of the fifteen lanthanides plus scandium and yttrium

A rare-earth element (REE) or rare-earth metal (REM), as defined by the International Union of Pure and Applied Chemistry, is one of a set of seventeen chemical elements in the periodic table, specifically the fifteen lanthanides, as well as scandium and yttrium. Scandium and yttrium are considered rare-earth elements because they tend to occur in the same ore deposits as the lanthanides and exhibit similar chemical properties, but have different electronic and magnetic properties. Rarely, a broader definition that includes actinides may be used, since the actinides share some mineralogical, chemical, and physical characteristics.

Mischmetal

Mischmetal (from German: Mischmetall – "mixed metal") is an alloy of rare-earth elements. It is also called cerium mischmetal, or rare-earth mischmetal. A typical composition includes approximately 55% cerium, 25% lanthanum, and 15-18% neodymium with other rare earth metals following. Its most common use is in the pyrophoric ferrocerium "flint" ignition device of many lighters and torches, although an alloy of only rare-earth elements would be too soft to give good sparks. For this purpose, it is blended with iron oxide and magnesium oxide to form a harder material known as ferrocerium. In chemical formulae it is commonly abbreviated as Mm, e.g. MmNi5.

Monazite phosphate mineral series

Monazite is a reddish-brown phosphate mineral containing rare-earth metals. To be more specific, it represents a group of minerals. The most common species of the group is monazite-(Ce), that is, the cerium-dominant member of the group. It occurs usually in small isolated crystals. It has a hardness of 5.0 to 5.5 on the Mohs scale of mineral hardness and is relatively dense, about 4.6 to 5.7 g/cm3. There are at least four different "kinds" (actually separate species) of monazite, depending on relative elemental composition of the mineral:

Bastnäsite bastnäsite mineral series

The mineral bastnäsite (or bastnaesite) is one of a family of three carbonate-fluoride minerals, which includes bastnäsite-(Ce) with a formula of (Ce, La)CO3F, bastnäsite-(La) with a formula of (La, Ce)CO3F, and bastnäsite-(Y) with a formula of (Y, Ce)CO3F. Some of the bastnäsites contain OH− instead of F− and receive the name of hydroxylbastnasite. Most bastnäsite is bastnäsite-(Ce), and cerium is by far the most common of the rare earths in this class of minerals. Bastnäsite and the phosphate mineral monazite are the two largest sources of cerium and other rare-earth elements.

Praseodymium Chemical element with atomic number 59

Praseodymium is a chemical element with the symbol Pr and atomic number 59. It is the third member of the lanthanide series and is traditionally considered to be one of the rare-earth metals. Praseodymium is a soft, silvery, malleable and ductile metal, valued for its magnetic, electrical, chemical, and optical properties. It is too reactive to be found in native form, and pure praseodymium metal slowly develops a green oxide coating when exposed to air.

Sillamäe Town in Ida-Viru County, Estonia

Sillamäe, is a town in Ida-Viru County in the northern part of Estonia, on the southern coast of the Gulf of Finland. It has a population of 13,666 and covers an area of 10.54 km². Sillamäe is located at the mouth of Sõtke River.

Gold extraction

Gold extraction refers to the processes required to extract gold from its ores. This may require a combination of comminution, mineral processing, hydrometallurgical, and pyrometallurgical processes to be performed on the ore.

Bayan Obo Mining District District in Inner Mongolia, Peoples Republic of China

Bayan'obo Mining District,, or Baiyun-Obo or Baiyun'ebo, is a mining town in the west of Inner Mongolia, People's Republic of China. It is under the administration of Baotou City, the downtown of which is more than 120 kilometres (75 mi) to the south.

Yttrium Chemical element with atomic number 39

Yttrium is a chemical element with the symbol Y and atomic number 39. It is a silvery-metallic transition metal chemically similar to the lanthanides and has often been classified as a "rare-earth element". Yttrium is almost always found in combination with lanthanide elements in rare-earth minerals, and is never found in nature as a free element. 89Y is the only stable isotope, and the only isotope found in the Earth's crust.

Cerium Chemical element with atomic number 58

Cerium is a chemical element with the symbol Ce and atomic number 58. Cerium is a soft, ductile and silvery-white metal that tarnishes when exposed to air, and it is soft enough to be cut with a knife. Cerium is the second element in the lanthanide series, and while it often shows the +3 oxidation state characteristic of the series, it also exceptionally has a stable +4 state that does not oxidize water. It is also considered one of the rare-earth elements. Cerium has no biological role in humans and is not very toxic.

Molycorp Inc. was an American mining corporation headquartered in Greenwood Village, Colorado. The corporation, which was formerly traded on the New York Stock Exchange, owned the Mountain Pass rare earth mine in California. It filed for bankruptcy in June 2015 after changing competitive circumstances, declining prices on output and a 2014 restructuring. It was purchased by its largest creditor Oaktree Capital Management and was reorganized as Neo Performance Materials.

The rare earth industry in China is a large industry that is important to Chinese internal economics. Rare earths are a group of elements on the periodic table with similar properties. Rare earth metals are used to manufacture everything from electric or hybrid vehicles, wind turbines, consumer electronics and other clean energy technologies. The elements are also important to national governments because they are used in the defense industry. Twenty percent of rare earth demands are for use as permanent magnets. Permanent magnets can be used for a variety of applications including serving as essential components of weapons systems and high performance aircraft.

Thor Lake

Thor Lake is a deposit of rare metals located in the Blachford Lake intrusive complex. It is situated 5 km north of the Hearne Channel of Great Slave Lake, Northwest Territories, Canada, approximately 100 kilometers east-southeast of the capital city of Yellowknife. Geologically located on the Canadian Shield it is mostly composed of peralkaline syenite. The Blatchford Lake complex was created in the early Proterozoic, 2.14 Ga ago. The deposit is divided in several sub-structures. In a small zone at the northern edge of the syenite, the T-Zone, minerals like bastnäsite, phenakite and xenotime can be found.

Round Top Mountain mountain in United States of America

Round Top Mountain is a mountain that lies at the western end of the Sierra Blanca area in Hudspeth County, Texas near the town of Sierra Blanca, Texas. The area includes the Finlay Mountains, Triple Hill, and Sierra Blanca quadrangles as well as parts of the Fort Quitman and McNary quadrangles. Round Top Mountain is known for containing deposits of beryllium as well as the largest deposit of heavy rare-earth elements in the United States.

Regolith-hosted rare earth element deposits

Regolith-hosted rare earth element deposits are rare-earth element (REE) ores in decomposed rocks that are formed by intense weathering of REE-rich parental rocks in subtropical areas. In these areas, rocks are intensely broken and decomposed. Then, REEs infiltrate downward with rain water and they are concentrated along a deeper weathered layer beneath the ground surface.

References

  1. ↑ "The Californian Rare Earths Mine Caught Between Trump and China". Bloomberg News. September 26, 2018. Retrieved November 7, 2018.
  2. ↑ Gordon B. Haxel, James B. Hedrick, and Greta J. Orris, "Rare earth elements – Critical resources for high technology", US Geological Survey, Fact Sheet 087-02, 17 May 2005.
  3. ↑ Geological Sciences Department (2008). "Mountain Pass Rare Earth Mine". California State Polytechnic University, Pomona. Archived from the original on 2008-10-01. Retrieved 2009-03-04.
  4. ↑ Margonelli, Lisa (May 2009). "Clean Energy's Dirty Little Secret". The Atlantic . Retrieved 2009-08-05.
  5. 1 2 Castor, Stephen B. (2008). "Rare Earth Deposits of North America". Resource Geology. 58 (4): 337. doi:10.1111/j.1751-3928.2008.00068.x.
  6. 1 2 David Danelski, Expansion in works for S.B. County mine with troubled environmental past Archived 2011-07-13 at the Wayback Machine , The Biz Press, February 9, 2009.
  7. ↑ "USGS Minerals Yearbook—1999" (PDF). U.S. Geological Survey. Retrieved July 27, 2018.
  8. ↑ "Mineral Commodity Summaries: Rare Earths—2003" (PDF). U.S. Geological Survey. Retrieved July 27, 2018.
  9. ↑ Molycorp Inc. Prospectus for Initial Public Offering
  10. ↑ Brickley, Peg (June 23, 2017). "Mountain Pass Mine Approved for Sale to JHL, QVT, Shenghe". Wall Street Journal.
  11. ↑ "Mountain Pass sells for $20.5 million | MINING.com". MINING.com. 2017-06-16. Retrieved 2018-11-07.
  12. ↑ "The Californian Rare Earths Mine Caught Between Trump and China". www.bloomberg.com. Retrieved 2018-10-09.
  13. ↑ Lisa Margonelli, Clean Energy's Dirty Little Secret, "The Atlantic", May 2009.
  14. ↑ British Geological Survey, Rare Earth Elements, PDF file, p. 25, 29.
  15. ↑ Jeremy Hsu, "Shortage of rare earth minerals may cripple U.S. high-tech, scientists warn Congress", Popular Science, 17 March 2010.
  16. ↑ Jeremy Hsu, "U.S. military supply of rare earth elements not secure", TechNewsDaily, 14 April 2010.
  17. ↑ BRADSHER, KEITH (2010-09-24). "China halts exports of minerals crucial to Japanese industry HONG: Customs officers at ports stop rare earth elements amid fishe". International Herald Tribune, Hong Kong. thejakartapost. Retrieved 2010-11-01.
  18. ↑ Amid Tension, China Blocks Crucial Exports to Japan, New York Times, 22 SEP 2010.
  19. ↑ "Caught Between Trump and its biggest market, America's sole rare earths mine is an unusual victim in the US- China trade war". South China Morning Press. (published 05-26-2019)
  20. ↑ Bloomberg May 30, 2019

Other references

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