The results are in for the initial laboratory test work from Lindian Resources’ maiden drilling program at its Gaoual bauxite project in Guinea, with the company declaring that it has a high-grade conglomerate bauxite play on its hands at the Bouba plateau. Lindian said the average grades from the primary Bouba plateau samples were 56% alumina and the “total available alumina” was in excess of 51% when measured at low temperatures.
The company said that Bouba is predominantly gibbsite rich and is geochemically uniform across the plateau, which will make for an easy processing flow sheet at the back end, when it is eventually put through a mill.
Gibbsite is one of three minerals that make up aluminium bauxite ores, with the other two minerals being boehmite and diaspore.
Testing bauxite also involves looking at other components such as the “total available alumina”, or “TAA” and reactive silica, because these parameters essentially define how efficient and economical the eventual extraction process may be.
The goal is to discover a deposit that is high in total available alumina and low in reactive silica, which is a nuisance during processing.
If the early numbers from the XRF are anything to go by, it appears at face value at least that Lindian’s deposit might meet these lofty goals.
The TAA values at low temperatures were in excess of 51% alumina, at high temperatures the average results came in at 92.2% alumina.
At Bouba, the reactive silica content averaged 6.2% with just 3% measured at low temperatures.
According to ALS Laboratories, quantifying the impurities in bauxite deposits is important because of their detrimental effects when it comes to refining the alumina.
ALS also said that a higher reactive silica content can lead to higher caustic soda consumption during the refining process and can also result in a higher concentration of alumina being lost to tailings.
The Bouba conglomerate bauxite has been geologically defined over an area of about five kilometres square now, whilst Lindian’s other deposit, the in-situ Mamaya plateau is about 11 kilometres square.
Overall, the average available alumina from Mamaya was 49.1% and the reactive silica content was just 5.3%.
The company said that most of its remaining samples will reach Perth in the coming weeks and that it will soon move to enveloping a resource around its Guinea deposits.
Lindian Managing Director Shannon Green said: “It is a fantastic milestone to finally be able to communicate these terrific results following the receival of both the XRF and digestion test work for the initial drilling program and most exciting is that the results show the truly world class nature and quality of this incredible and unique resource.”
Lindian’s flagship Gaoual project is located around 165 kilometres northeast of the Kamsar port and is now shaping up to be quite a valuable play, particularly as the metallurgy is looking good now that the initial assays are in.
The company can acquire an initial 51% interest in Gaoual from KB Bauxite Guinea SARLU and its sole shareholder, Guinea Bauxite, by pumping USD$1 million into the ground over the next few years.
It also has the right to move to a 75% holding via a longer-term deal after certain project milestones have been achieved and further monies spent on the project.
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By Matt Birney
