ASX-listed Lindian Resources has tabled world-class, high-grade alumina numbers at its Gaoual conglomerate bauxite project in Guinea, West Africa. The maiden resource estimate for Lindian’s readily mineable surface deposit of 102 million tonnes at 49.5 per cent alumina used a grade cut-off of 40 per cent alumina. The indicated resource includes uber-rich tonnage totalling 84Mt at 51.2 per cent alumina, using a higher-grade cut-off of 45 per cent alumina.
Lindian Resources said its 102Mt JORC-compliant resource has been defined on the Bouba plateau area of its Gaoual project which has seen some ultra-high-grade alumina numbers, including four holes at Bouba South grading between 54.9 and a staggering 58.5 per cent alumina.
Lindian’s independent geological expert, Mark Gifford said: “Assaying and test work results continue to show the impressive high-grade nature of the Bouba Conglomerate Bauxite Plateau. The exceptionally high alumina grades combined with the potential ability to screen out the fine-grained quartz makes the Bouba Conglomerate Bauxite a valuable addition to the Guinea resource landscape. The Company’s total resource base will be further increased by the inclusion of the Mamaya Plateau drill and assay results.”
The alumina grades at Gaoual are in rare air, comparing favourably to Australia’s own bauxite mines, including Weipa in Queensland and Gove in the Northern Territory, which are amongst the world's highest-grade deposits averaging between 49 and 53 per cent alumina, according to Geoscience Australia, or “GA”.
Gaoual sits on the Bouba plateau, close to major operating bauxite mining companies with significant infrastructure making it possible to develop a quick pathway to market for the ore, particularly given the desire of the Guinean Government to open up access to existing infrastructure, according to Lindian.
Whilst Gaoual is not the only bauxite resource in Guinea, its 102Mt is comparable to Australia’s Gove, at 190Mt plus, according to GA, giving a scale that should provide leverage in Lindian’s negotiations to access the export infrastructure already in place and operating.
Lindian Resources Chairman, Asimwe Kabunga said: “I am very excited that the Company has delivered a successful maiden resource of over 100Mt at the Bouba Plateaux. This has confirmed our belief in the quality of our Gaoual Project, with bauxite grades superior to product currently being sold in the international markets. The Project’s location near other major producing mines and their associated infrastructure, places the Company in a good position to progress the Project through to production.”
Lindian said the resource is predominantly gibbsite with boehmite at lower levels, however silica levels are higher than other regional “in situ” bauxites due to the addition of wind-blown aeolian sands, post-deposition.
Digestion test-work has confirmed that most of the silica present is in the form of fine-grained quartz grains which can be readily separated by employing a simple screening methodology.
The company said the effect of this process would be to reduce the silica content, effectively raising the alumina content of the product with minimal loss of tonnage. Price improvement from this process, plus cost benefits from accessing the regional infrastructure could easily offset any additional costs associated with the screening process.
Lindian looks to have confirmed a deposit which has the twin benefits of high total available alumina combined with a simple solution to address the reactive silica content which can be a nuisance during processing.
The next step will likely see Lindian integrating its new resource estimate into a pre-feasibility study that could include third-party access to infrastructure as a pathway to rapid development.
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By Matt Birney
