Tietto Minerals Ltd (ASX:TIE) is encouraged by results from comminution test work completed on diamond drill core selected from the Abujar‐Gludehi (AG) gold deposit, part of its 2.2-million-ounce Abujar Gold Project (AGP), in Côte d’Ivoire, West Africa.
The Bond indices indicate a relatively easy milling standard gold‐bearing ore with potential for low-cost processing.
Tietto managing director Dr Caigen Wang said: “These physical test work results are very promising, demonstrating that the mineralisation at AG is not abrasive and is of medium to moderate hardness.
“Simply speaking, the transitional and fresh mineralisation (together accounting for 98% of the AG mineral resource) will be relatively cheap to crush and grind with a simple communication flowsheet using single-stage crushing followed by milling, and low power consumption."
Bond Abrasion Index
The Bond Abrasion Index is a measure of the abrasiveness of an ore with the average results from the test work 0.28 for fresh ore and 0.06 for transitional ore.
These values are normal for a non-abrasive gold-bearing ore.
Bond Rod Mill Work Index
The average results for the Bond Rod Mill Work Index, which measures the resistance of the ore to grinding to a coarse product size, are 13.2 kilowatts per tonne for fresh ore and 8.5 kilowatts per tonne for transitional ore.
This indicates that the ore is of medium to moderate hardness and slightly more competent at coarser sizes, which could indicate a pebble crushing circuit may be required for the mill.
This will be determined by comminution circuit modelling during the feasibility study.
Bond Work Ball Mill Index
The results from the Bond Work Ball Mill Index, which is used to calculate the power requirements to grind ore to a typical ball mill product, averaged 12 kilowatts per tonne for fresh ore and 9 kilowatts for transitional ore.
This shows that the ore is primarily of medium hardness, with the transitional ore composite being quite soft.
The oxides are very soft and brittle, however, it’s still beneficial to do at least one effective test on the oxides for the purposes of the pre-feasibility study.
At this stage, the oxides only make up about 2% of the total resource.
Abujar Gold Project.
SMC test work
The SMC suite of test work is intended to provide parameters for use in comminution modelling.
Results indicate that the ore is likely to be amenable to single-stage crushing followed by SAG milling (SSAG) in closed circuit with or without a pebble crusher.
Test work ongoing
The program is ongoing and will investigate grind size establishment and gravity recovery, as well as cyanide leach optimisation.
Wang said: “Mintrex in Perth is managing the program which has now advanced to grind size establishment, gravity recovery and cyanide leach optimisation (building on preliminary work completed in 2016 which demonstrated exceptional gravity gold recovery of over 80% and CIL gold recoveries in excess of 98%).
This work is expected to be completed in quarter three of 2020.
Drilling program continues
Tietto’s 50,000-metre drilling program is continuing at Abujar using the fleet of company-owned drill rigs to drive cost efficiency.
The aim is to increase the resource inventory of existing deposits as well as identifying new prospects within Abujar’s 70-kilometre-long gold corridor where 90% of the strike remains to be tested.
Wang said: “Drilling continues on-site and we remain on schedule for delivery of an updated resource in quarter three of 2020.
“This updated mineral resource and results from the current metallurgical test-work program will underpin a PFS scheduled for quarter 2021.”
The company expects to report on more drilling results in the coming weeks, including new prospects along strike extensions of the AG deposit and the APG deposit.