July 26, 2016 Mineral Deposits

Volume 8 | Issue 1

It’s as good as having found a goldmine in savings. In the case of Molycorp, the mine targets molybdenum, which is selling at record levels

It is one advantage of living in modern times, the ability to dig into the earth and excavate a mineral that was formed approximately 24.5 million years ago. It is another huge advantage of doing business in the ’00s that the price of the mineral molybdenum (generally referred to as moly) is at record levels: up almost 700 percent since 2001.
“Moly wasn’t recognized for years,” relates Vice President of Sales and Marketing Bob Noll. “If you look at the 10-year average, it was probably $3 to $3.50 a pound, ballpark. This current run started in 2002.” What sparked the demand was the growth of emerging economies, specifically China’s, and the primary use for moly as a key component in the formulation for stainless steel.

This is good news for Molycorp, which has been mining molybdenum since 1914 at its Questa molybdenum mine, located near the western portion of the Taos Range of the Sangre de Cristo mountains in Taos County, northern New Mexico. The mineral is a soft, metallic blue color, and consists of the metal molybdenum combined with sulfur. Molybdenite occurs in economic quantities in relatively few places in the world. The region, northern New Mexico-to-central Colorado, is unique in that several world-class occurrences of molybdenite have been and are being mined as primary molybdenum deposits.

Moly, however, is not the only mineral mined and processed by Molycorp. The company also supplies a group known as rare earths, which serve a range of applications, from cell phones, televisions, computers, and transportation systems; two are responsible for the red in color TVs. The rare earths are valuable for the environment because they pave the way for cleaner air and enable new pollution-control systems. Molycorp’s Mountain Pass, Calif., mine is the only North American resource for rare earths. Capabilities at Mountain Pass range from extracting the ore out of the ground to producing high-grade oxides. Surface mining methods are designed to produce 2,000 tons of crushed ore per day.

In addition to these operations, Molycorp maintains equity interest in CBMM (Companhia Brasileira de Metalurgie e Mineracao), the largest producer of Niobium in the world. Niobium is used in the metallurgy of microalloyed and other specialty steels for numerous industries including automotive, pipelines, shipbuilding, and rail. CBMM is the only niobium producer present in all market segments.

Not so rare
Rare earths mined by Molycorp – bastnasite, cerium, europium, lanthanum, neodymium, praseodymium, and yttrium – are grouped together on the Periodic Table because they exhibit similar properties. They are relatively soft metals, with high melting points and boiling points and are very reactive. They burn easily in air, are strong reducing agents and at elevated temperatures, many will ignite and burn vigorously. Termed “rare earth” minerals because, at the time of their discovery, the thought was that their presence in the earth was, indeed, rare, it now is understood that the rare earths are more abundant, and that even the scarcest of their family are more common than the platinum-group metals.

Ironically, the rare aspect of their makeup lies in the fact that their abundant presence in one location is, well, rare, making mining activities economically unfeasible. “Years ago,” Noll explains, “they’d be located in beach sands; they could literally be scooped up and not necessarily mined.” But this posed a problem because the sands were high in radioactive materials, causing disposal concerns.

This makes Molycorp’s operation all the more important, especially in light of the fact that the uses for the rare earths and moly are so widespread that they trail across myriad industrial sectors. “There’s been talk of their use in magnetic refrigeration,” Noll says, in which the power source comes from magnetics instead of electricity. “Their use in magnetics is a continual area of research,” says Noll. The rare earths, he adds, provide the most power and highest operating temperatures in small packages; as an example: Walkmans utilize high-power magnets processed with neodymium. “There’s more research going into the rare earths to get more power while continually shrinking the motors for mini devices. These applications depend on magnets.”

As Noll explains, these rare earths lend their unique abilities and characteristics to a range of applications. Bastnasite, in particular, is a mineral that contains various amounts of all the rare earths. The other minerals and their uses are:
• Lanthanum (La): The major use of lanthanum is in cracking catalysts used to refine crude oil into gasoline and other fuels. In the area of high-performance optics, lanthanum is the key to modifying glass crystal structure and the refractive index. Advances in the quality of high-tech digital cameras, video cameras, and many other sensitive optical applications would not be possible without lanthanum or other rare earths.
• Neodymium (Nd): In the area of electronics and communications, neodymium is a key component of permanent magnets used in a large variety of motors and mechanical systems such as cell phones, portable CD players, and computers. Cellular phones contain both neodymium magnets and capacitors, which produce powerful electronic generation to boost the power for these communication devices. In the automotive sector, small powerful permanent magnets based on neodymium are at the heart of anti-lock brakes (ABS), air bags, and many other systems dependent on electric motors in the modern vehicle. Additionally, neodymium lasers are used in material processing, drilling, spot welding and marking, and also in medicine. In the medical field, the magnetic wave generation on which the non-ionic radiation MRI (magnetic resonance imaging procecure) is solely dependent on the neodymium magnet.
• Yttrium or ytterbium (Yb): Yttrium containing garnets are used in cellular communications devices by industries such as defense, satellites, and phones. Yttrium-europium phosphors produce the red color in televisions and computer screens. For the defense industry, yttrium and other rare earths are used as a stabilizer and mold former for exotic lightweight jet engine turbines and other parts. Yttrium also helps stabilize materials used in rocket nose cones. Yttrium as well as many other rare earths can be formed into laser crystals specific to spectral characteristics for military communications.
• Praseodymium (Pr): Along with neodymium, praseodymium is used to filter certain wavelengths of light. Its color allows production of various pigments used in coloring products such as ceramic tile and glass. Praseodymium is used in photographic filters and airport signal lenses and in premium quality optical products such as mirrors and lenses. As part of an alloy, praseodymium is used in permanent magnet systems designed to make smaller and lighter motors. Praseodymium is also used in automobile and other internal combustion engine pollution control catalysts.
• Cerium (Ce): Cerium is an environmentally critical component in the manufacture of pollution-control systems for automobiles and oil refineries. TVs and computers rely on cerium to help produce high quality parts. The space shuttle program is dependent on engineering ceramics containing cerium.
• Europium (Eu): Combined with yttrium, the properties of this mineral are responsible for the perfect red color in televisions and computer screens around the globe.

In addition, molybdenum (Mo) plays an integral role in the iron and steel industry, which consumes 75 percent of the molybdenum produced. Molybdenum is primarily used as an alloying element in the production of alloy, stainless and tool steels, and cast iron. Most high strength steels contain some amount of molybdenum up to the 8 percent level. Moly-based lubricants allow steel structures to move fluidly against each other, especially at high temperatures and pressures. There also is a wide range of chemical products that utilize pure molybdenum in various forms, such as rust inhibitors, pigments and fertilizer additives.

Mined for profit
Molycorp’s rare earths operation in Mountain Pass is unique because it is one of the few places on earth where geology and chemistry form an economically mineable lanthanide ore-body. The Precambrian bastnasite ore deposit is 250 feet thick and dips into the ground at a 40-degree angle. Mining is carried out with 85-ton haul trucks and 13-cubic-yard, front-end loaders. Geological projections, ore-body mapping, blast hole cutting assays, and metallurgical testing provide necessary input to ensure consistent, on-grade ore production. Once mined, ore is hauled to a crushing plant, reduced to less than 3/8-inch in size, and fed to the ball mill where grinding liberates the mineral grains prior to froth flotation.

The flotation operation concentrates the bastnasite ore from an initial 8.5 percent to a 60 percent lanthanide oxide (LnO) product. An enriched 70 percent LnO product is produced after flotation with a hydrochloric acid leach, which dissolves the carbonate gangue. The bastnasite concentrates are thickened, filtered, and dried for shipment or sent to the company’s separations facilities for further recovery operations.

The company’s moly mining operations in Questa, N.M., involve buildings located at just above eight thousand feet elevation, with the current underground working levels generally extending two thousand feet. The mine is an underground gravity block cave mine extracting a world-class primary molybdenum ore deposit. The mine is designed to produce 18,000 tons per day, seven days a week.

The history of the molybdenum mine goes back to 1914 when two prospectors, Fahey and Johnson, staked 10 claims in a place called Sulphur Gulch and named them all “Phyllis,” with numbers one through 10. They had discovered a dark, metallic material, but didn’t know what it was, or what it could be used for. The common belief at the time was that it was graphite that could be used for functions ranging from lubricating wagon axles to shoe polish. In the early summer of 1918 the R&S Molybdenum Mining Company had entered the Red River Valley and underground mining of the high-grade veins was underway. The ore was hauled several miles by horse and mule drawn wagons to the June Bug Mill which was the relocated gold mill from Elizabethtown.

In June of 1919 R&S Molybdenum Mining Company stopped work and underwent reorganization, becoming the Molybdenum Corporation of America (eventually becoming Molycorp).

The discovery of rare earths between Clark Mountain, a dominant peak in northeastern San Bernardino County, Calif., and Interstate Highway 15 (formerly U.S. 91 and before that the Arrowhead Trail) occurred in April of 1949. Between 1900 and 1920 many small lead, zinc, copper, gold and tungsten mines were started and some production recorded. The Sulphide Queen gold deposit, adjacent the Mountain Pass lanthanide ore-body, was discovered in 1936. The presence of lanthanide metals was not suspected until Herbert Woodward, later a metallurgist for Molycorp, and his partner Clarence Watkins, discovered a heavy, light brown mineral on mining claims they had located nearly a mile north of the Sulphide Queen gold mine. Specimens of the mineral were taken to Boulder City, Nev., where a Bureau of Mines mineralogist identified them as bastnasite, a fluor-carbonate mineral containing the cerium group of lanthanide metals. The United States Geological Survey confirmed the bastnasite discovery and made a public announcement in November 1949. Molycorp became interested and bought these claims in February 1950.

While these operations have been suspended, Molycorp expects to be up and running shortly. The problem, says Noll, has to do with the area used to retain what’s called the “mill tailings” – residue from the milling operation. The basin used to store these mill tailings has been in constant use for 30 years and was finally closed down in 2002 when it was deemed that it had reached the end of its useful life.

“We mined a lot of material in 2002 to stock as inventory,” he explains. “We’re building a new tailings area now and are just about through the planning and design phase.” The old area, he adds, is undergoing remediation and will be closed and transformed into a sustainable environment. As the company gears up for what promises to be several decades more of successful mining operations, Molycorp sees its potential as limited only by what the earth has produced – and, at least for the last 24.5 million years, the earth has been prolific.

Subscribe to Industry Today