Mineral Processing and Metallurgical StudiesMetallurgical processing of the Nechalacho ore has the objective of separating the valuable minerals from the gangue minerals and extracting the rare metals from those minerals. The on-going metallurgical test program is based on composite samples of drill core obtained between 2007 and the present. The majority of the work is being conducted at the SGS Minerals Services laboratory, Lakefield, Ontario (SGS), under the supervision of Avalon’s Process Engineer Dezhi Qi, P. Eng and J.R. Goode, P. Eng., Consulting Metallurgist. The testwork includes the recovery of rare earth elements (REE), but also other rare metals present in the Nechalacho deposit, such as tantalum (Ta), niobium (Nb) and zirconium (Zr), and possibly also gallium (Ga). In addition, flotation testwork is being conducted at Xstrata Process Support (XPS) in Sudbury, Ontario and the Baogang Research Institute of Mining in China. Metallurgical processing of the Nechalacho mineralization to produce saleable REE and other rare metal products will be a four-stage process:
Bench scale flotation investigations using locked cycle tests (LCT) have proven a robust flotation route that yields a concentrate representing just less than 20% of the feed mass and containing approximately 80% of the REE, Zr, Nb, and Ta. This process has shown to work on several samples of different ore types and grades. Further trials to optimize the flotation process are in progress. As well as the bench scale testing, two minipilot plants (two tonnes and one tonne) have been completed at XPS and a pilot scale concentrate production run of three tonnes at SGS. These pilot plants have supplied concentrate for hydrometallurgical testing as well as helping in advancing the flotation process design. Hydrometallurgical tests have been conducted on bulk samples of flotation concentrate produced in large-scale, flotation LCT and the pilot plant operations. These tests have investigated sulphuric acid baking to decompose REE minerals and sodium hydroxide (caustic) cracking to break down Zr, Nb and Ta minerals - processes commonly used to decompose refractory minerals. The sulphuric acid bake tests demonstrate that REE extraction is about 90%. In the next step, the high zircon residue from the acid bake process is cracked using sodium hydroxide which allows the bulk of the Zr, residual REE, Nb and Ta to be dissolved in an acid leach step. Selective precipitation and solvent extraction is then used to isolate the REE, Zr, Nb, and Ta. Current work is focused on recovery of the elements of interest from the acid bake and post-caustic crack leach solutions. Avalon has also commenced pilot scale testwork of the acid bake process at SGS as part of a planned 40 week series of hydrometallurgical pilot tests.Please refer to Avalon's news release for the latest updates on metallurgy and separation. Also refer to Avalon's latest Prefeasibility Study NI 43-101 reports for further information. News Releases Related to Metallurgy
News Releases Related to Separation
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