The Mt Thirsty cobalt project is located 16 km northwest of Norseman, Western Australia and is jointly owned by Conico Ltd and Barra Resources Ltd, together the Mt Thirsty Joint Venture (MTJV). The project contains the Mt Thirsty cobalt-nickel oxide deposit that has the potential to emerge as a significant cobalt producer. The MTJV is progressing a PFS on the project using industry leading consultants led by Amec Foster Wheeler Australia (Wood).

• PFS level metallurgical test work results of the whole ore leach case by Wood independently validate the scoping study assumptions
• Beneficiation test work successfully concentrates target asbolane mineral into one half of the mass and increases potential leach feed grades to as high as 0.33% Co
• Technical and economic assessment identifies whole ore leach as superior to beneficiation on multiple financial and non-financial criteria
• Whole ore leach selected as the go-forward case for the PFS
• Optimisation of leach conditions underway aiming to further increase leach recoveries
• Engineering to a PFS level of accuracy scheduled for Q1 2018.

The MTJV’s PFS Manager, Barra Resources Managing Director and CEO Sean Gregory, said “These high-quality technical results and key design decisions continue to de-risk the development pathway for the Mt Thirsty project. Mt Thirsty is reaffirmed as an advanced high grade and low capex solution to the flourishing battery industry’s need for low cost and sustainable sources of cobalt, an otherwise scarce commodity.”

The aim of the test work conducted for the PFS to date has been to enable the front-end of the flowsheet to be selected. The base case is for the whole of the ore to be fed into the leaching process (whole ore leach case). The alternative case is for the ore feed to be beneficiated by rejecting the fine slimes component to reduce the volume and increase the feed grade of the leach feed (beneficiation case).

In theory, beneficiation has the potential to reduce the capital costs by allowing the size of the hydrometallurgical circuit to be reduced to account for the lower volume of leach feed and the higher percentage solids that can be pumped with a coarser beneficiated leach feed. The beneficiation concentrate is also expected to be richer in the target asbolane mineral that hosts the leachable cobalt. The beneficiation tail is expected to contain more cobalt in fines, dominantly goethite, that is less easily leached. For beneficiation to be the preferred case, these benefits must outweigh the loss in leachable cobalt and nickel metal to tails.

A series of metallurgical tests and economic modelling of the results have enabled a preferred frontend flowsheet to be selected.