SASKATCHEWAN – In order to complete the preliminary economic assessment report, GREAT WESTERN MINERALS of Saskatoon has been awaiting results of the stage 2 metallurgical tests of material from the Hoidas Lake rare earth project 50 km northeast of Uranium City. The purpose of the continued testing was to identify alternatives to whole rock hydrochloric acid leaching, which was originally investigated.
Now the labs of SGS LAKEFIELD have made what Great Western calls a “breakthrough” in processing. SGS has employed optical ore sorting, using a microprocessor to analyze the data and select particles to be rejected from the stream.
In the case of the Hoidas Lake material, the rock was crushed to 12-mm size and fed through the sorter. The end result was that the sorter was able to separate the material precisely enough that 92% of the rare earth elements reported to 60% of the retained material. In other words, this technique could reject 40% of the rock mined as waste, resulting in significantly lower milling costs; less material being milled to recover the majority of the contained rare earth elements. It is anticipated that even better results can be achieved by calibrating the microprocessor and software to specifically accommodate the Hoidas Lake mineralization.
The second phase 2 test with positive results used another SGS technology called QEMSCAN. This is a scanning electron microscope used to precisely determine where the rare earth elements are located in the mineralized particles and how they are being liberated using different grind sizes and different reagents. Developmental testing shows the potential for using sulphuric acid and a finer grind to deliver as high a recovery of the rare earth elements as with the hydrochloric acid base case, thereby consuming significantly less acid.
The Hoidas Lake mineralization was originally discovered 50 years ago. More information is available at www.GWMG.ca.