Coal – A Possible New Source of Rare Earth Elements

The US Department of Energy’s National Energy Technology Laboratory (NETL) has identified high concentrations of rare earth elements (REE) in coal samples collected from several American coal basins and is doing research to see if these minerals are economically recoverable.

According to the Energy Business Review, samples

were collected from the Illinois, Northern Appalachian, Central Appalachian, Rocky Mountain Coal Basins, and the Pennsylvania Anthracite regions. The samples were found to have high REE concentrations greater than 300 parts per million (ppm).

NETL said: “Concentrations of rare earths at 300ppm are integral to the commercial viability of extracting REE from coal and coal by-products, making NETL’s finding particularly significant in the effort to develop economical domestic supplies of these elements.”

NETL has partnered with West Virginia University (WVU), the University of Kentucky (UK), Tetra Tech, and the XLight for the research project.

The current difficulties and high expenses associated with REE extraction has left the U.S. dependent on foreign REE imports. Currently, China supplies about 90 percent of REE used in industry.

Rare earth elements are vital to modern society. Some of the uses include computer memory, DVDs, rechargeable batteries, cell phones, catalytic converters, magnets, fluorescent lighting, night-vision goggles, precision-guided weapons, communications equipment, GPS equipment, batteries, and other defense electronics.

There are 17 naturally occurring rare earth elements: yttrium, scandium, lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium.

Despite the name “rare earths” the more common REE are each similar in crustal abundance to commonplace metals such as chromium, nickel, copper, zinc, molybdenum, tin, tungsten, and lead, but REE rarely occur in economic concentrations, and that’s the problem.

The U.S. used to be self-sufficient in REE due to one deposit, Mountain Pass in the Mojave desert, California, just west of Las Vegas, Nevada. That mine, a carbonatiteintrusion with extraordinary contents of light REE (8 to 12% rare earth oxides) was discovered in 1949 and began production in 1952. Mining ceased in 2002 due to low prices and some environmental regulatory trouble triggered by a tailings spill. However, the mine was reactivated in 2012 but went bankrupt in 2016. Another company (a Chinese consortium) purchased the property in July, 2017, and is working to restart operations.

Some other U.S. rare earth resources are shown on the map below.

See a power-point essay on REE that explains geology, deposit types, and many more details.

One of the authors of that power-point says:

“For example, a typical coal contains 62 parts per million (ppm) of total rare earth elements on a whole sample basis. With more than 275 billion tons of coal reserves in the United States, approximately 17 million tons of rare earth elements are present within the coal—that’s a 1,000-year supply at the current rate of consumption.” —Dr. Evan Granite, NETL

The report also says that abandoned tailings piles from coal and iron mines may be important resources of REE.

Dr. Granite says that the United States consumes around 16- to17 thousand tons of REE each year, and this demand could be completely satisfied by extracting rare earths from domestic coal and coal by-products.

See also:

Rare Earths Resources in the US

How we use rare earth elements

Rare Earth Elements Deposits in New Mexico

Lateritic, supergene rare earth element (REE) deposits

The Arizona Geological Survey has just made available a paper on lateritic rare earth element (REE) deposits around the world. There is some potential for these deposits in the southeastern U.S.

The following is from the paper introduction.

Most current research and exploration efforts for REE deposits are focused on primary hard rock
deposits. These include REE mineralization associated with carbonatites, peralkaline igneous complexes, granites, pegmatites and migmatites.

Primary minerals in primary deposits may include bastnäsite, monazite, xenotime, eudialyte, allanite, zircon, apatite, and a variety of more uncommon minerals. Extraction and concentration of REE minerals and metallurgical processing to remove and separate the various REE can be difficult and expensive, and the beneficiation for each deposit may be unique.

In contrast to primary deposits, laterites, those soils formed during intense weathering of bedrock under tropical or sub-tropical (i.e., hot and humid) conditions, are important sources of viable economic mineral deposits. Lateritic weathering results in the breakdown of primary rocks and minerals, and concentration of metals such as aluminum, iron, manganese, nickel, gold, phosphorous, and niobium. Many occurrences of rocks containing these elements had minerals that were difficult or costly to mine or process to obtain these elements; e.g. nickel in olivine and aluminum in mica, clay, and feldspar. Laterization changes the mineralogy and hence how these elements are situated in relation to the bonding of these minerals. Metallurgical methods, mostly developed during the last 50 years, allow economic recovery of these elements from lateritic minerals.

Paper Citation:
Cocker, M.D., 2014, Lateritic, supergene rare earth element (REE) deposits, in, Conway, F.M., ed., Proceedings of the 48th Annual Forum on the Geology of Industrial Minerals, Phoenix, Arizona, April 30 – May 4, 2012. Arizona Geological Survey Special Paper #9, Chapter 4, p. 1-18.

The paper has some interesting cross-sections showing how these deposits were formed.

The paper may be downloaded for free:
http://repository.azgs.az.gov/sites/default/files/dlio/files/nid1570/ree_cocker_chp4.pdf

 

 

 

How we use rare earth elements

There are 17 naturally occurring rare earth elements (REE): yttrium, scandium, lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium. Although not very familiar to most people, these elements are used by us all every day. By 2015, world demand for rare earth minerals is expected to reach 210,000 tons per year up from 136,100 tons in 2010.  Currently, China provides most of our supply.

The National Mining Association has produced an info-graphic showing the major uses of the rare earth elements:

Despite the name “rare earths” the more common REE are each similar in crustal abundance to commonplace metals such as chromium, nickel, copper, zinc, molybdenum, tin, tungsten, and lead, but REEs rarely occur in economic concentrations, and that’s the problem.

The U.S. used to be self-sufficient in REE mined from one deposit, Mountain Pass in the Mojave desert, California, just west of Las Vegas, Nevada. That mine, a carbonatite intrusion with extraordinary contents of light REE (8 to 12% rare earth oxides) was discovered in 1949 and began production in 1952. Mining ceased in 2002 due to low prices and some environmental regulatory trouble triggered by a tailings spill. However, the mine was reactivated in 2012. Some other U.S. rare earth resources are shown on the map below.

See also:
Rare Earth Elements Deposits in New Mexico

Rare Earth Elements Deposits in New Mexico

The Arizona Geological Survey has just published a report on rare earth element potential in New Mexico by Virginia T. McLemore. The full report is available for free download here (6Mb). The report was produced as part of the 48th Annual Forum on the Geology of Industrial Minerals.

From the report:

“The REE (rare earth element) family includes 15 lanthanide elements (atomic number 57-71), yttrium (Y, atomic number 39), and scandium and are commonly divided into two chemical groups, the light REE (La through Eu) and the heavy REE (Gd through Lu, Sc, and Y). REE are lithophile elements (or elements enriched in the crust) that have similar physical and chemical properties, and, therefore, occur together in nature. However, REE are not always concentrated in easily mined economic deposits and only a few deposits in the world account for current production.”

There are several types of rare earth element deposits. The report discusses deposits in alkaline igneous rocks, carbonatites, REE-Th-U hydrothermal veins, pegmatites, placer deposits, and other REE-bearing deposits.

The report contains several interesting photographs and illustrative diagrams, and an appendix listing the mining districts and type of deposits contained therein. Give it a look.

 

China Controls Rare Earth Elements Supply

Recently economist Paul Krugman complained that “China accounts for 97 percent of the world’s supply of minerals that play an essential role in many high-tech products, including military equipment.” He was writing about Rare Earth Elements (REE). There are 17 naturally occurring rare earth elements: yttrium, scandium, lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium. Not very familiar to most people, but they are used by us all every day. Some uses include liquid-crystal displays on computer monitors and televisions, fiber optic cables, magnets, glass polishing, DVD and USB drives in the computer, catalytic converters, and petroleum cracking catalysts, batteries (the Prius uses 10 pounds of lanthanum), fluorescent lights, missiles, jet engines, and satellites. In other words, these elements are critical to our high-technology world.

Despite the name “rare earths” the more common REE are each similar in crustal abundance to commonplace metals such as chromium, nickel, copper, zinc, molybdenum, tin, tungsten, or lead , but they rarely occur in economic concentrations, and that’s the problem.

The U.S. used to be self-sufficient in REE mined from one deposit, Mountain Pass in the Mojave desert, California, just west of Las Vegas, Nevada. That mine, a carbonatite intrusion with extraordinary contents of light REE (8 to 12% rare earth oxides) was discovered in 1949 and began production in 1952. Mining ceased in 2002 due to low prices and some environmental regulatory trouble triggered by a tailings spill. Some REE are still produced by processing stockpiles. Mountain Pass may resume mining next year.

According to the U.S. Geological Survey, several other rare earth prospects in the U.S. are being explored: Bear Lodge in Wyoming; Diamond Creek in Idaho; Elk Creek in Nebraska; and Lemhi Pass in Idaho-Montana. Others sources that may come on line soon are Hoidas Lake in Saskatchewan, Canada; Nechalacho (Thor Lake) in Northwest Territories, Canada; Kangankunde in Malawi; and the Nolans Project in Northern Territory, Australia. At the Mount Weld rare-earth deposit in Australia, the initial phase of mining of the open pit was completed in June 2008.

For the time being, however, China controls the supply of vital minerals resources.

For more information see: http://pubs.usgs.gov/fs/2002/fs087-02/fs087-02.pdf

UPDATE: See a story in the Atlantic: Chinese Rare Earth Embargo Spreads  and

China to limit exports of ‘rare earth’ minerals vital to energy tech