Avalon making good progress at Lake Zone rare earth deposit in Canada
Avalon Rare Metals Inc (TSX: AVL) reported good progress at the Thor Lake rare metals project in Canada’s North-West Territories. The results of the testwork completed to date demonstrate that approximately 80 percent of the rare earth element (REE) containing minerals can be recovered into a mineral concentrate by flotation type methods and that the minerals in this concentrate can be hydrometallurgically "cracked" to get the REE earths into solution.
In fact, at least two different alternative methodologies have been identified for achieving this, and current work is focused on defining the most cost-efficient methodology, the company said.
The metallurgical testwork has been based on composite samples of drill core obtained between 2007 and 2008, including a main bulk sample generated by drilling during May, 2008 in the central part of the deposit. The samples were selected by Avalon geologists as representative of the Basal Zone portion of the Lake Zone deposit.
The metallurgical work was initiated in July 2008, following the completion of detailed mineralogical studies and has been progressing steadily as a series of trials designed to determine the optimal process flowsheet for REE recovery from the Basal Zone mineralization.
The work is being conducted at the SGS Minerals Services laboratory in Lakefield, Ontario. Specific work to recover the other rare metals present in the Lake Zone ore such as tantalum, niobium, gallium, zirconium and hafnium has not yet been undertaken although it has been noted that several of these follow the REE and therefore are also likely recoverable.
Metallurgical processing of the Lake Zone mineralization to produce a saleable REE product is envisioned as a two-stage process. The first stage will be conventional milling and froth flotation to produce a mineral concentrate.
The second stage will be hydrometallurgical treatment of the mineral concentrate in order to extract the REE from the minerals, bring them into solution, partially refine them, and then precipitate them out to produce one or more chemical concentrates in the form of high-grade mixed REE carbonates. These mixed REE carbonates will ultimately require further processing to separate the individual REE, which may initially be done by third parties or ultimately built into an integrated business model.
Preliminary market studies also indicate that mixed REE carbonates containing a high proportion of heavy REE, will likely be a saleable product as is.
Preliminary testing has proven a robust flotation route that yields a concentrate containing between 82 percent and 85 percent of the REEs, zirconium and niobium. This process has been shown to work on several samples of different ore types and grades, Avalon said.
Further trials to optimize the flotation process are in progress. These tests were all performed on drill core composites collected from the Basal Zone in the central part of the deposit.
Once a preferred hydrometallurgical process has been identified, the company will initiate testwork on the separation of the rare earth elements zirconium and niobium from the leach solutions. It is expected that the solutions will be amenable to classical rare earth separation methods.
The results from ongoing flotation testing are expected to be available by October and will be used for plant design engineering in the prefeasibility study.
Finally, future work is being planned to assess the feasibility for recovery of gallium as a further potential valuable by-product in the Basal Zone ore, the company added.
