Emerging Democratic Republic of Congo producer AVZ Minerals (ASX: AVZ) reports that drilling beneath the historic Roche Dure pit floor at the old Manono mine has produced new high-grade lithium and tin hits which will now be factored into the existing definitive feasibility study (DFS).
As a result, the company said it will re-run the geological resource model as that portion of the pit floor was previously labelled as waste due to lack of information.
That information is now in — and it could change the economics of the project for the better.
Not only were the grades impressive beneath the pit floor, but the mineralisation was present in thick intervals, one intercept going through 245.15m of mineralisation.
Major intersections included 180m at 1.8% lithium oxide and 1,119 parts per million tin, 245.15m at 1.73% lithium oxide and 926ppm tin, and a third hole returned 218.6m at 1.69% lithium oxide and 1,152ppm tin.
Isolated zones of lithium oxide grades greater than 2% were intersected in two of the holes, including 28m at 2.08%.
Possibility of finding new higher-grade core
AVZ said the striking of high grades in what was modelled as waste material may the beginning of a much higher-grade core.
This will need further investigation to determine the possibility of finding more significant tonnages of high-grade core that could feed the plant in its early years of operation to shorten the pay-back period.
AVZ managing director Nigel Ferguson said drilling also reported higher grade portions developing within the northern portions of the ore body, and that these may even coalesce both up dip and along strike.
The three holes drilled were collared in fresh or slightly weathered pegmatite from the top of the holes.
Mine design to be optimised in light of new drilling
The historic Manono mine was mined for its tin content between 1919 and 1982 but little prospecting has been done there since 1960, the year the then-Belgian Congo gained its independence from Brussels.
Mr Ferguson noted that the final assay results show strong mineralisation from the pit floor surface.
“Now these assays have been reported they will be merged with our current database and we will re-run the geological resource model to reclassify that portion of the pit floor,” he said.
“Following on from the geology remodelling and coupled with the improvements of plant design parameters, we will then check the previous mine design against the updated model to optimise the mine design, generate new ore reserves and revisit the DFS results.”