Middle Island Resources has reported that ore sorting trials to upgrade gold mineralisation at its flagship Two Mile Hill underground deposit will be completed this month. Preliminary test work has proved highly successful in pre-concentrating ores via optical sorting methods. Resource definition drilling is also underway and is designed to increase resources at the Sandstone gold project.
Aspiring gold producer Middle Island Resources is nearing completion of its definitive, ore sorting investigative campaign for the flagship Two Mile Hill tonalite deeps deposit, in the Murchison region of W.A.
Previous sighter tests and two scoping trials of ore composites from the deposit have proved highly successful in upgrading the gold mineralisation in sorted ore parcels, with the current test work program set to be completed by the 19th June.
Initial sorting trials demonstrated that the Two Mile Hill ores were amenable to pre-concentration, with a high selectivity of gold mineralisation using X-Ray transmission and optical sensors.
The X-Ray sensors sort crushed ore streams based on their bulk density, with gold and sulphide minerals having a much higher density than that of the quartz waste rock at Two Mile Hill.
Colour sensors use optical properties of the quartz to separate the host rock waste from the valuable gold and sulphide mineral products.
Middle Island’s preliminary test work showed that ore sorting could deliver an increase in overall grade of between 185% - 257% with gold recoveries in excess of 93%.
The definitive test work underway includes permutations around crush sizes and grade range designed to refine the preliminary results.
A positive ore sorting outcome for the Two Mile Hill deposit, has the potential to significantly reduce the company’s unit haulage and process operating costs, thereby optimising the venture and increasing efficiency and hence value.
The company also reported that resource definition drilling programs at Two Mile Hill are well advanced, with three diamond drilling tails now completed.
Once the program has concluded, final assay results are expected to become available in early July.
Middle Island’s Managing Director Rick Yeates said: “Assuming positive results from these work streams, bulk underground mining at Two Mile Hill becomes a very real opportunity that would substantially extend and enhance the presently envisaged project production schedule.”
“Middle Island looks forward to reporting the results of drilling and ore sorting during the June and September quarters of 2018.”
The current mineral resource inventory for the Sandstone gold project is just over 12 million tonnes grading 1.38g/t gold for 537,000 ounces, with some small tonnages not yet 2012 JORC-compliant.
The project extends from 140m to 700m deep below the base of the quantified open pit resources.