Australian based Stellar Resources (ASX-SRZ) has completed a metallurgical optimisation study which has increased potential tin recovery for the Severn deposit of the company’s Heemskirk project in Tasmania to 79.5% Sn, a 7.1% improvement on the 2013 PFS.
Optimisations included elimination of a heavy media separation circuit, production of a coarser primary grind and removal of the silica flotation circuit, reducing tin losses and resulting in higher recoveries. The final concentrate will contain 45% Sn, within the optimum range of 40%-45% calculated to maximise smelter returns. Projected capital and operating costs are also lower due to the simplified process design.
The Severn deposit represents 60% of the mineral resource at Heemskirk with the remaining 40% contained within the Queen hill and Montana deposits. Stellar resources suggest the metallurgical process is likely to be applicable to these other deposits, although limited sample availability has so far prevented adequate testing. The optimisation of processing for the Severn deposit increases the total potential recovery across all deposits by 4.5% to 72.8% and also increases potential production by 4.5% to 4,520 tpy of tin-in-concentrate.
Stellar is undertaking additional metallurgical development work at St Dizier and has plans to commence testing at the Queen hill and Montana deposits in the future. Pilot and larger scale batch testing is planned along with testing of ore variability, both necessary for completion of a DFS.
Stellar’s managing director, Peter Blight commented: “(The optimisation study) has demonstrated a step up in recovery for Severn and … has provided robust data for optimising design criteria and processing conditions ahead of a definitive feasibility study to commence in 2015.”