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By Shane Lasley
Mining News 

Critical Minerals Alaska – Rare Earths

It may not be Alaska's geological endowment that elevates the state to an important domestic source of these high-tech elements

 

Last updated 3/16/2018 at 4:23am

Peggy Greb, U.S. Department of Agriculture

Rare earth elements are key ingredients in a wide range of modern products such as terabyte hard-drives that fit in the palm of your hand, high-efficiency power generation and sophisticated military hardware. Clockwise from top center: praseodymium, cerium, lanthanum, neodymium, samarium, and gadolinium.

Before color televisions hit the markets in the 1960s, rare earths where a curious group of elements that had the distinction of occupying their own separate section at the bottom of the periodic table but had very few practical applications. Over the ensuing 50 years, however, this group of 15 lanthanides plus yttrium and scandium have been discovered to possess unique properties that make them key ingredients in a wide range of modern products such as terabyte hard-drives that fit in the palm of your hand, high-efficiency green-power generation and sophisticated military hardware.

Green energy is a huge driver of demand for the special properties REEs possess. For example, the high energy magnets used in the motors and generators of a single 3 mega-watt wind turbine requires roughly 1,300 pounds of rare earths.

According to the U.S. Geological Survey, the value of rare earths imported in the United States increased by roughly 27 percent in 2017.

"The estimated value of rare-earth compounds and metals imported by the United States in 2017 was $150 million, a significant increase from $118 million imported in 2016," the USGS penned in its 2018 minerals report.

The growing demand driven by the increased use of REEs in today's high-tech devices, coupled with China currently dominating the supply side of the equation, has resulted in the U.S. Geological Survey listing the group of technological elements among 23 minerals considered critical to the economic wellbeing and security of the United States.

"China has been the leading producer of REEs for decades and since the late 1990s it has accounted for more than 90 percent of global production, on average," the USGS wrote in its January report on minerals critical to the United States.

Recent work by the USGS and Alaska Division of Geological & Geophysical Surveys have unveiled wide swaths of Alaska that either host known deposits of rare earth elements or are highly prospective for these increasingly important ingredients to modern devises.

To compile and rate Alaska's potential for REEs, the federal and state geological agencies developed a geospatial tool that can integrate and analyze a massive load of geologic information and use this data to estimate the state's potential for a large array of critical minerals, including rare earths.

After crunching the data, this new tool confirmed and expanded upon areas of Alaska already known for their rare earth potential and turned up at least one surprisingly hot REE hunting ground in the state.

"Some of the areas that showed high potential were already known, but many of these areas had not previously been recognized," explained Sue Karl, an Alaska-based USGS research geologist and lead author of the Alaska critical minerals study.

It may not be Alaska's geological endowment, however, that elevates the state to an important domestic REE supplier – at least not directly.

Bokan Mountain

The best known and most advanced deposit of rare earths in Alaska is found at Ucore Rare Metals Inc.'s Bokan Mountain project on Prince of Wales Island in Southeast Alaska.

"REE prospects at Bokan Mountain may have the greatest immediate potential for development of an REE resource in the state," USGS penned in its 2017 report on Alaska's critical mineral potential.

Located on Prince of Wales Island, Bokan Mountain hosts a deposit with 4.79 million metric tons of indicated resource averaging 0.6 percent (63.54 million pounds) total rare earth oxides.

While not particularly high-grade, roughly 40 percent of the rare earths fall into the more valuable heavy REE category.

Heavy REEs are thus named due to their atomic weight and include such critical elements as europium, terbium and dysprosium. While all rare earths possess unique characteristics that make them valuable to certain modern applications, the heavy ones tend to be less abundant and more valuable.

Ucore completed a preliminary economic assessment in 2012 that outlines an underground mine at Bokan Mountain that was envisioned to produce 2,500 tons of rare earth oxides per year during the first five years of full production; including an annual output of 105 tons of dysprosium oxide, 15 tons of terbium oxide, and 568 tons of yttrium oxide.

In a quest to find a more efficient and environmentally sound means of separating the rare earths at Bokan, however, Ucore came across a unique way of separating the notoriously tightly interlocked rare earths that could have more potential for providing a domestic source of REEs than developing a rare earth mine on U.S. soil.

Separating rare earths

This search for a cutting edge REE separation technology led Ucore to IBC Advanced Technologies and that company's proprietary molecular recognition technology, commonly known as MRT.

The basic idea behind the MRT process is that "SuperLig resins" are engineered to grab ions based on various traits such as size, chemistry and geometry. Loaded into a series of columns, these resins latch onto the targeted material suspended in a solution that is pumped through the columns. Simply rinsing the resin with a mildly acidic solution releases a nearly pure version of the material the resin is engineered to bind to.

This technology, which has been around for roughly three decades, has already been proven in mining. Notable applications include platinum group metals refining and removing bismuth impurities from copper.

Before Ucore and IBC, however, no one had ever tried to utilize MRT to separate the hard to break apart rare earth elements.

With a pilot plant dubbed SuperLig-One, IBC and Ucore extracted individual REEs from a solution derived from Bokan Mountain, proving that MRT could be used to separate rare earths.

"We've demonstrated the capability to separate the 16 individual REE, at greater than 99 percent purity and 99 percent recovery, from PLS (pregnant leach solution) derived from Bokan-Dotson Ridge REE ore," said IBC President and CEO Steven Izatt. "Dysprosium, for example, has been separated from Bokan PLS in a pilot plant operation at the 99.99 percent level with 99 percent recovery."

This means that essentially all of dysprosium fed into SuperLig One came out the other end as a virtually pure product.

After proving the concept at the pilot plant scale, Ucore has been looking for an ideal U.S. locale for the first Strategic Metals Complex, a commercial scale REE separation facility.

Ease of access to international shipping corridors, industrial infrastructure, permitting, and potential for local incentives and state funding programs were among the considerations weighed when looking for the best place to build the first SMC.

This search led Ucore to Ketchikan, a Southeast Alaska coastal town that is about 35 miles northeast of its Bokan Mountain project.

Hosting a deep-sea port on the Pacific Rim and situated roughly 60 miles from a Canadian rail-head that connects the project to all of North America, Ketchikan has a number of advantages for a metals separation facility that is looking to produce high purity rare earths from REE-bearing feedstock sourced from around the globe.

"Engineering and economic studies have confirmed that Ketchikan is our preferred location to construct our first strategic and critical metals separation facility," said Ucore COO Mike Schrider.

For the initial feedstock for this facility, Ucore is seeking concentrates that contain the rare earths needed to feed the increasing demand for electric vehicles, as well as individual REE oxides required for other U.S. commercial and military technologies.

So, the first rare earths produced in Alaska seem likely to come from sources outside the state. Feedstock from locations in the Lower 48, South America, Africa, Asia, and Australia are under consideration.

The Ketchikan SMC, however, could also eventually serve as a rare earth separation facility for a mine at Bokan.

"The intent is also to maintain the processing flexibility and capacity to accommodate ore concentrate from the Bokan-Dotson Ridge project, once that project has been developed," Schrider said.

Beyond Bokan

While Bokan Mountain is the most advanced rare earth deposit in Alaska, it is far from the only potential geological source of these technological elements found in the state.

In fact, USGS and DGGS geologists identified a stretch of Southeast Alaska, extending 200 miles northwest from Bokan Mountain, as a great place to look for REEs.

Numerous rare earth prospects – including Doris Bay, Salmon Bay and Stone Rock – have been identified on this stretch of Southeast Alaska that is dominated by Prince of Wales Island.

The critical minerals study done by USGS and DGGS also found that most of Alaska's gold-rich Interior region is prospective for rare earths.

This includes Yukon-Tanana, a roughly 100-mile-wide swath of Interior Alaska that extends from the Yukon-Alaska border to the Roy Creek REE prospect north of Fairbanks.

Interior Alaska's most exciting REE hunting ground, however, is Kokrines-Hodzana, a 200-mile-long area of Interior Alaska just north of the Yukon River that includes known REE hunting grounds like Ray Mountains and Kokrines Hills.

"The Ray Mountains and the Kokrines Hills area of the state is one of the places that stand out of rare earths," Avalon Development President Curt Freeman told Mining News in 2012.

One of the interesting characteristics of the Ray Mountains area is this area hosts significant placer REE occurrences. Having the material already broken down to sands and gravels deposited in stream beds could make the first stages of REE recovery easier and less expensive.

Ucore holds mining claims that blanket an 11,400-acre area of the Ray Mountains that hosts placer deposits with potentially economic concentrations of REEs, tin, tungsten, tantalum and niobium.

To better understand the placer potential of its Ray Mountain property, Ucore collected alluvial samples from upper Kilolitna River, Ray River, and No Name Creek during a field investigation carried out in 2011.

Using a shaking table – a standard gravity separation tool common to placer gold mining – Ucore concentrated these samples collected from the Ray Mountain drainages.

That assays of these concentrates returned up to 50 percent tin; as much as 10 percent rare earths; and 0.01 to 1 percent tungsten, tantalum and niobium. Heavy rare earths – including terbium, dysprosium, erbium and yttrium – make up 15 to 25 percent of the total rare earth content in the majority of samples.

As much as 60 percent of the rare earths recovered from samples collected at No Name Creek are the prized heavy REEs.

The company said most of the initial samples were collected directly from surface exposures, and the heavy mineral content can be expected to increase at greater depths within the alluvium. In some areas the gravels are reported to be as much as 100 meters deep.

"The Ray Mountains project has select areas rivaling HREE content at our Bokan property, and the remarkable advantage of collateral tin, niobium and tantalum mineralization which enhances prospective values per ton." Ucore President and CEO Jim McKenzie said at the time.

Possibly the most intriguing find made by USGS and DGGS' assessment of Alaska's rare earth potential is a 15,000-square-mile region at the west end of the Alaska Range, an area that includes Mount Estelle and the Revelation Mountains.

While this area contains a few small known REE occurrences, these do not account for the high potential the USGS geospatial tool has given to a large portion of this region – a sign that this area is exceedingly underexplored and a great place to hunt for rare earths.

The area does host Windy Fork, a placer REE deposit reminiscent of the Ray Mountain placers in Interior Alaska.

Bulk sampling at Windy Fork in the 1990s indicates that the Windy Fork placer deposit contains roughly 17 million cubic meters of placer material containing rare earths, primarily cerium; niobium; titanium; and zirconium; all of which have been deemed critical minerals by the USGS.

With the geospatial tool, USGS and DGGS identified four other regions of Alaska to hunt for rare earths:

Northern Alaska Range, an area arcing about 220 miles west from Tok;

Kuskokwim-White Mountains, which stretches about 500 miles southwest from Yukon-Tanana;

Darby Hogatza, an area of know uranium and REE occurrences that arcs 200 miles east from the Seward Peninsula; and

Porcupine, an area centered on Spike Mountain in far northeastern Alaska.

U.S. Geological Survey

A geospatial tool developed by USGS and DGGS identified eight regions of Alaska that host rare earth deposits or are prospective for this suite of critical minerals.

Given Alaska's vast and underexplored rare earth potential, along with a new REE separation facility being proposed there, the United States has the option of looking to its 49th State for a domestic supply of these increasingly critical ingredients for modern technology.

Editor's Note: "Critical Minerals Alaska – Rare Earths" is the second of a series of articles to be published in North of 60 Mining News that investigates Alaska's potential as a domestic source of minerals deemed critical to the United States. At least 15 of the 23 critical minerals identified by the U.S. Geological Survey – antimony, barite, beryllium, cobalt, fluorspar, gallium, germanium, graphite, indium, platinum group elements, rare earth elements, rhenium, tantalum, tellurium, tin and vanadium – are found in Alaska.

 

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