Hi Chezd
A few things. Haddington performed an extensive testing programme on their tailings, commissioning a drill programme in the main tailings dam behind the present day processing plant (20 holes) and in the Hills End Pit, which was used as a tailings dam when the main dam filled up (5 holes). The highest grade of lithium in any of those 25 holes was less than 0.15% Li20. The grade of the tantalum was also less than 100 ppm. Haddington could see the writing was on the wall for SOG, so they embarked on a very ambitious exploration programme. That is when they discovered the Creekside deposit and the rubidium/lithium anomolies in 2006. They sent 25 samples to Canada, to see if the Falcon gravity bowl could concentrate any of the valuable minerals to an appreciable extent but they were all too fine (especially the tantalum, which is a very soft mineral and generally was milled down to <35 microns after passing through two mills)
During my time at Bald Hill, we also marked out 12 trenches in the main tailings dam, and retrieved three representative samples form each trench and had them sent away to a local, reputable laboratory. All of the 36 results came back with lithium assays below 0.15% Li20, 100 ppm tantalum and 0.1 ppm gold. So, in a nutshell I can tell you emphatically that a retreatment of those one and a half million tons of tailings is exceedingly unlikely. The kicker is that of the 0.15% Li20, over a third is lepidolite, the curse of the southern pegmatite swarms. If you google the list of successful lepidolite (mica) mines in Australia, please forward me that list as I'd love to see it. It may be possible to convert a blend of lepidolite and spodumene into a final product suitable to feeding a battery or glass making operation but I have not seen it. Maybe one of the other punters can help here?
Also, I think that you have misquoted, or else the original report is incorrect. the 30-50% spodumene in any of the Bald Hill ores is simply not true. Ask anyone on site now; the highest spod grade of any of the current plant feed is around 10%. The DMS roughly treats 150 tph of ore, yielding 10% (15 tph) spodumene and 90% pegmatite (135 tph) tailings. These numbers are very rough and are only used to illuminate a point.
The one and a half million tons of tailings was indeed pegmatite tailings. Haddington mined according to the economical tantalum envelope >200 ppm tantalum and did not follow spod grades. The average feed grade in the 2001-2005 days was about 0.4% Li20, of which about half would have reported to the tantalum con (and hence lost into Greenbushes tailings or by-product stockpiles). Remember the yarn that "high spodumene values were encountered in tantalum cons produced in 2015" Remember that all of the ultrafine ore in the tailings dams is light. It is spiral tailings and hence does only contain trace quantities of heavy minerals. But if anyone can produce evidence of grades higher than 0.15% Li20, I encourage them to evidence them here.
Haddington picked all of the eyes out of that area (except for the Creekside Tantalum deposit) and they moved onto greener pastures. They changed their name to Altura and refocussed their attention on lithium and rare earths. There is nothing left at Bald Hill except for a kaleidoscope of shattered dreams.
