• Pit floor drilling program commences to potentially upgrade some
Inferred Resources to Indicated Resources
• New Ore Reserves to be generated from updated mine design
• Geotechnical site investigation of plant site underway
• Site for tailings storage facility confirmed and geotechnical sampling program commenced
• Phase 2 hydrogeological modelling field program commenced
AVZ Minerals Limited (ASX:AVZ or “the Company”) is pleased to advise that planned drilling has commenced at its flagship project, the Manono Lithium and Tin Project (“Manono Project”).
Pit Floor Drilling – The “Wedge”
Geological diamond core resource drilling has recommenced on the Roche Dure pit floor after COVID-19 travel restrictions to the Democratic Republic of Congo (“DRC”) were lifted in mid-September (Figure 1). Ten new geological resource holes for 1,700m of diamond drilling will be conducted during the next four weeks.
Previous drilling at Roche Dure has defined more than 400mt of potential ore at an average grade of 1.65% Li2O (Refer to ASX Announcement dated 8 May 2019: Significant Upgrade in Measured and Indicated Mineral Resource) but the material immediately below the then water filled open pit could not be accessed physically and therefore remained at an Inferred Resource category. This means the pit floor rock could not be considered as mineable ore in the existing mine plan. It is expected that some of
the pegmatite may be upgraded to an Indicated Resource / Probable Reserve status by drilling this previously inaccessible area.
The updated geological resource is not expected to increase overall
resource tonnes but the current combined Indicated and Measured Resource tonnage is expected to increase. Assay results are expected in November 2020 if the drilling can be completed by the end of October 2020.
Updating the mine plan
Once the ‘wedge’ material directly under the pit floor is drilled and assay results returned, it is expected that some of this previously classified waste rock may then report as mineable ore. This new data will allow the existing mine design to be re-run and optimised. There will be positive advantages from this work being undertaken with the most obvious being that two years of potential pre-stripping will be avoided and the payback period for financing will be positively impacted pro-rata.
The re-run of the mine design, following the upgrade of the geological resource estimate towards the end of the year, will also allow for plant design optimisation studies, highlighted in the published Definitive Feasibility Study, to also be completed and incorporated into the new modelling.
Consequently, a new Ore Reserves Estimate and financial model will be generated based on the revised mine design, which are expected to be published towards the end of December 2020.
Plant Site Geotechnical Program
As part of the pre-production planning, AVZ recently received survey information over the plant site, coupled with updated site design work has allowed “fine tuning” of the final location of the plant site.
This has allowed planning of the plant site geotechnical investigation program and the siting of 38 new test pits and nine geotechnical boreholes sighted under significant weight bearing locations (Figure 2).
PQ sized diamond core from the nine holes will be sent to a specialist geotechnical laboratory in Johannesburg for an array of specialist load bearing strength tests. This data will allow for detailed planning of the future earthworks program for construction of the new plant site.
Tailings Storage Facility (TSF) Update
A technical decision has been made to optimise the storage of future mine tailings by placing them inside the waste rock dump to the west of the Roche Dure open pit (Figure 3). The advantages of this design, which is commonly adopted in Australia and known as an Integrated Waste Landform (IWL) are several but include minimising land disturbance by storing the tailings inside a rock barrier, increased stability of the overall TSF, substantial savings on dam wall construction and ease of future rehabilitation.
Five locations within the IWL footprint have been selected for geotechnical drilling to be conducted, to examine the underlying soil and rock properties of the proposed site (Figure 3) and these investigative drillholes will be completed as part of the overall plant site geotechnical investigation to be completed in the next few weeks. Samples from these boreholes will be sent to the specialist lab in South Africa for testing.
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