The mining newspaper for Alaska and Canada's North
The mining newspaper for Alaska and Canada's North
U.S. Forest service approves drill program, interim camp; program to provide engineers with data to finalize rare earth mine plan
The United States Forest Service has given Ucore Rare Metals Inc. the green light to complete a field program that will generate the data engineers need to complete a plan of operations and feasibility study for the Bokan-Dotson Ridge rare earth element project on Prince of Wales Island in Southeast Alaska.
Ucore plans to deliver these advanced engineering studies to the U.S. Forest Service, providing the regulatory agency with the information to initiate a National Environmental Policy Act review, the first step in gaining the permits needed to develop a mine at Bokan Mountain.
"The development of the plan of operations is a significant step forward for the project and submitting the document to the USFS to initiate the NEPA review will be an important milestone for the company," said Ucore President and CEO Jim McKenzie.
The permits granted by the U.S. Forest Service allow Ucore to drill 27 holes, a program that includes infill and geotechnical drilling as well as the development of monitoring wells, generating valuable information for project engineers.
The construction of an interim field camp to serve as a base of operations at Bokan Mountain was also permitted, an allowance Ucore is not taking lightly as the company closes in on seeking permission to build a mine in the Tongass National Forest.
"Permission to build an onsite camp to replace the company's former barge-based facility is a significant milestone not granted lightly by the US Forest Service. This achievement, together with Bokan's location in an area already designated for resource development - known as a USFS Mineral Prescription - are positive indicators for future development at Bokan," McKenzie said.
Engineering critical
Engineering is playing a critical role in keeping the footprint small and the economics robust at Bokan Mountain, a strategic source of rare earth elements located in the United States' largest national forest.
A preliminary economic assessment completed late in 2012 proposes a 1,500-metric-ton-per-day underground mine, a 750-tpd mill and a state-of-the-art processing facility. This operation is anticipated to produce 2,250 metric tons of rare earth oxides per year during the first five years of full production; including an annual output of 95 metric tons of dysprosium oxide, 14 metric tons of terbium oxide, and 515 metric tons of yttrium oxide.
Now it's up to Knight Piésold Ltd., Tetra-Tech Inc. and PND Engineering to hammer out the details of the avant-garde operation offered in the scoping level study.
At a 0.4 percent total rare earth oxide cut-off grade, the Dotson Zone deposit at Bokan Mountain hosts an inferred resource of 5.3 million metric tons averaging 0.65 percent total rare earth oxides. While not particularly high grade, this deposit has two important features: roughly 40 percent of the rare earths in the resource are the higher value heavy rare earth oxides; and the REE mineralization is concentrated in a swarm of steeply dipping veins.
"The key thing is the waste rock in between the veins is absolutely barren," according to Ucore COO Ken Collison.
Collison, a mining engineer with extensive experience in operations and permitting, explained that this stark contrast between REE-enriched veins and barren rock allows for the use of an x-ray sorter to scan mined material as it heads up a conveyor and use a blast of high pressure air to reject REE-barren rocks before they drop into the grinder, reducing the mill feed by half.
Ucore, which has been testing this technology for the past couple of years, continues to get better results as it increases the scale of testing.
A 20-metric-ton sample, collected earlier this year from three locations within the Dotson Ridge deposit, was processed by a large scale x-ray transmission ore sorter at a TOMRA (formerly Commodas Ultrasort) in Germany. Results show that 52 percent of the feed was rejected as waste, with 96.3 percent of the rare earth oxides remaining in the material to be fed into the mill.
"The confirmation of XRT effectiveness at large scale is an important milestone in Ucore's march to mine construction," said McKenzie. "The company is the first in the rare earth industry to demonstrate XRT as a beneficiation technique; a technology already well-established in the tungsten and diamond mining sector. XRT shows the clear potential to dramatically reduce the volume of material feeding the mill facility and an equally dramatic increase in TREO ore grade without a great deal of processing."
After initial grinding, half of the remaining material can be skimmed by magnetic separation before getting a bath in nitric acid.
"So we are going to have 1,500 tons per day coming out of the mine, but we are going to have a 750-ton-per-day grinding circuit and then the leaching circuit, which is extensive, is only 375 tons per day," explained Collison.
In addition to the economic advantages associated with purchasing and operating a smaller mill, this setup provides environmental rewards.
While the PEA envisions a small, temporary facility to store tailings during the early stages of development, at a certain point the mine will consume all of the tailings produced to fill underground voids.
"The addition of an XRT circuit prospectively reduces capital and operating costs, with a smaller processing footprint than is the norm for REE facilities, and with no tailings facility at surface upon mine closure," said McKenzie. "A zero tailings footprint is a unique environmental objective, and we are aware of no other mine, rare earth or otherwise, that has accomplished such a design feature."
A 30-metric-ton bulk sample of Dotson Ridge material has been sent for XRT sorting. Ucore said the output from this sample will provide feed for a pilot plant at Bokan.
The pilot plant, scheduled for the fourth quarter, is the final stage of bulk-scale testing of the production circuit prior to the release of a bankable feasibility study and the prospective commencement of mine construction.
Pilot plant
Rather than an onsite, scaled-down version of the facility Ucore plans to operate at Bokan, the pilot plant will involve up-scale testing of the various components planned for the cutting-edge operation.
The XRT sorting being conducted in Germany is one portion of the pilot plant; the testing of a state-of-the-art technique that utilizes nanotechnology to separate the 16 different rare earth elements found in the Dotson Ridge deposit at Bokan is another.
Ucore is working with Montana-based IntelliMet LLC to pioneer an REE processing technique known as solid-phase extraction.
Though cutting edge, the SPE procedure follows a much simpler flowsheet than solvent exchange extraction, the method traditionally used to separate REEs. The less-complex nanotechnology process is expected to result in a smaller and more efficient facility for transforming Bokan Mountain ore into rare earth oxides.
In bench-scale tests, IntelliMet treated a representative sample of Bokan ore with nitric acid, generating a solution containing the rare earths and other elements contained in the ore. Before precipitating the REEs out of solution, the Montana-based lab was able to pull out more than 99 percent of the non-REE elements - including iron, uranium and thorium.
Once these "nuisance" elements are removed, the proposed SPE processing facility will use three stages of subclass segregation that will result in pure REE oxides precipitated out of the solution.
This promising technology has caught the Pentagon's attention. Last October, the U.S. Department of Defense entered into a contract with Ucore to conduct a mineralogical and metallurgical study at Bokan Mountain.
This six-month program, managed by the U.S. Defense Logistics Agency, is investigating the possibility of developing Bokan Mountain into a mine and processing facility that could supply the U.S. military with a domestic source of heavy rare earths.
While Bokan Mountain is rich in yttrium, dysprosium, terbium and a suite of other rare earths needed in weapons systems, the Pentagon's interest in Ucore seems to be as much about the state-of-the-art extraction technology as it is about the strategic metals stowed at its Southeast Alaska deposit.
"The Department of Defense's investment in the Bokan deposit and Ucore's proprietary SPE technology represents a significant step toward recapturing the rare earths technological lead surrendered to China decades ago," said McKenzie.
Under an agreement with the Defense Department, Ucore will provide the Pentagon with the most up-to-date data on this nanotechnology research.
A portion the pilot-scale testing is taking place in the Mineral Industry Research Laboratory at the University of Alaska Fairbanks.
This work - funded with US$297,000 provided by the Alaska Department of Commerce, Community and Economic Development in 2012 - will augment other studies on the processing and separation of rare earths as well as research conducted on procedures for handling waste rock.
State support
In addition to the UAF research funding, the State threw its weight behind SJR. 8, an Alaska Senate resolution that aims to boost rare earth exploration and development in the 49th state and Bokan Mountain, in particular.
"I think that is a significant move people should pay attention to because Alaska has a program to develop a total rare earth industry. They want, not just to be a supplier of the resource, they want to be a supplier of end-use goods using processed rare earths," said Jack Lifton, co-founder of Technology Metals Research.
SJR 8 recognizes the deposits at Bokan Mountain as "rich in the heavy rare earth elements of europium, gadolinium, terbium, dysprosium, thulium, holmium, erbium, ytterbium, lutetium, and yttrium" and "the only known (heavy rare earths) deposits in the world that have deepwater access, accessible labor, and prospective power sources."
Lesil McGuire, R-South Anchorage, sponsor of SJR 8, said, "Several experts have said it is likely that Alaska has one of the most significant rare-earth prospects in North America," said McGuire. "If we play our cards right, this could secure our future as the lead supplier of America's rare earth mineral needs."
Following unanimous support in both the Alaska House and Senate, Gov. Parnell signed the resolution into law in June.
Ucore hopes broad support, positive economics and relatively simple development plan will result in a short runway to production at Bokan Mountain.
If the company's schedule holds, Ucore has a target of 2016 to begin providing the United States with heavy rare earths from the Southeast Alaska deposit.
Over his more than 16 years of covering mining and mineral exploration, Shane has become renowned for his ability to report on the sector in a way that is technically sound enough to inform industry insiders while being easy to understand by a wider audience.
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