Encouraged by market projections and recent drill results, Avalon Ventures (AVL-V) plans to obtain a prefeasibility study on its Separation Rapids property, 60 km north of Kenora, Ont.
A program of infill drilling has confirmed the results of more widely spaced drilling done in late 1997 and early 1998. The preliminary resource estimate calculated after the first round of drilling indicated 7.1 million tonnes grading 1.29% lithium oxide (Li2O) and 0.35% rubidium oxide (Rb2O).
The new drilling also included two holes drilled downdip on the host pegmatite dyke, which intersected 54.5 metres grading 1.54% Li2O and 0.46% Rb2O and 86.3 metres grading 1.6% Li2O and 0.34% Rb2O, with cesium and tantalum credits. The true widths of the two deep intersections are calculated at 23 and 34 metres respectively.
The infill holes showed grades between 0.67% and 1.62% Li2O and between 0.29% and 0.45% Rb2O. The lengths of the intersections, which ranged from 6.2 to 108.7 metres, translated into true widths of 4 to 67 metres, and there appears to be good continuity of grades and widths between holes.
The lithium in the pegmatite is mainly held in petalite, a lithium aluminum silicate. The rubidium is a trace constituent in potassium feldspar.
Preliminary results from metallurgical testing on samples from the pegmatite, performed at Lakefield Research, have shown that selective flotation can recover 92% of the petalite and a large proportion of the feldspar. Tantalum, mainly held in the dense mineral tantalite, can be recovered by running the flotation tailings through a gravity concentrator.
The metallurgical study is continuing, and will include additional work to determine the mineral species holding the metals. A bulk sample is scheduled to be tested in May.
A study of the market for lithium, rubidium and tantalum, commissioned by Avalon, concluded that the project can generate annual returns of $13.5 million. Annual production of 58,000 tonnes of petalite would account for just over 60% of the net revenue. Recent prices for petalite concentrates are around US$270 per tonne, suggesting that the market study has assumed a very conservative net-back (ratio of net smelter return to gross metal value) of about 38%. The market for petalite, which is used in glass and ceramic products (and is a major constituent of heat-resistant borosilicate glasses) has grown considerably over the last decade and the study estimates that worldwide consumption could reach 1.5 million tonnes per year.
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