AVZ Minerals Ltd (ASX:AVZ) has updated its preliminary tin and tantalum recoveries following the reporting of the flotation test work results at its Manono Lithium and Tin Project in the Democratic Republic of Congo.
AVZ managing director Nigel Ferguson said: “As part of the recent flotation test programme, we now have initial recovery figures for the tin and tantalum from the undersize, -0.5 millimetre fraction, that can be compared for the first time to the dense media recoveries for these metals from the Phase 2 metallurgical programme.
“This has allowed us to complete a mass balance for the heavy mineral fractions for the first time.”
Tin and tantalum
Testing has shown that tin and tantalum is well liberated and easily recoverable from the -0.5 millimetre material.
Ferguson said: “The overall tin and tantalum recovery is 63% but having only been able to split the coltan from the cassiterite in the finer fraction sizes at this time, further work is required, potentially including the use of an on-site smelter to produce metal ingots for both security purposes and ease of transport to market.
“The tin grades are however, above 60% in both size ranges and are highly saleable products which could potentially contribute to reducing overall operating costs and to supply a significant and growing demand from the electronics market.
“AVZ is currently in discussions with several potential off take partners in this field.”
Alluvial heavy minerals
Six initial broad spaced, non-representative, alluvial tin and tantalum samples were produced from the testwork, which AVZ believes shows ‘exciting upside potential’.
Ferguson said: “In addition to the hard rock tin and tantalum at Roche Dure, we are now investigating recovery of the alluvial tin and tantalum present in significant quantities across the concession.
“As part of our social development programme, and in line with transparency in the supply of these minerals from Manono, we have commenced analysis of these alluvial heavy minerals to determine if the metal values warrant further investigation.”
Assay values ranged from 29.5% to 71.5% Tin dioxide (SnO2) as Cassiterite and from 2.14% to 4.18% Tantalum oxide (Ta2O5) as Coltan.
He said: “This confirms historical reports by independent geological consultants, Bear Dolhbere, of a significant alluvial tin field at Manono and it appears at least initially, that this material may also be economically recovered by working together with the community to maximise returns for both the Company and all stakeholders.”
The company will now aim to carry out cost/recovery investigations to determine the most effective recovery route for both the hard rock and alluvial minerals and whether or not the recoveries return an economic benefit.
Further work will also be needed to explore alternative economic and saleable concentrate options (for example combined tin/tantalum tin concentrate with tantalum and niobium credits).
It is expected on the back of these results that a work program will be implemented to assess the nature of all alluvial fields within Manono with the view to possibly placing them into production at some stage in the future.