The company has recently commissioned Tomra Ore Sorter Solutions Pty Ltd to assess the amenability of two bulk Horn Island samples to Tomra’s XRT ore sorting technology.
Diamond core totalling around 2 tonnes from the inferred resource area of 7.9 million tonnes at 1.9 g/t gold for 492,000 ounces was assessed along with a separate sample collected from legacy low-grade stockpiles from mining operations in the 1980s.
Results of the Tomra Ore sorter test-work demonstrated the suitability of this low-cost, low-energy processing solution.
High-volume feed rates of 48 tonnes per hour (tph) and 79 tph were applied with high gold recoveries of 94% and 93% respectively.
The Tomra system proved extremely efficient in separating mineralised sulphide vein material and rejecting predominantly barren granite host rocks.
“Results are extremely encouraging”
Alice Queen’s managing director Andrew Buxton said: “These results are extremely encouraging for the company.
“Yesterday’s (Wednesday’s) ASX announcement regarding the results of the second half of the company’s RC infill program set the scene in relation to the forthcoming update to the Horn Island Mineral Resource Estimate.
“However, most importantly, when one combine’s yesterday’s positive drill results with today’s Tomra ore sorting results, it is easy to be very optimistic about the future outcome of the Horn island Scoping Study.”
Testing the samples
Alice Queen recently engaged Tomra to test the Tomra proprietary XRT sorter systems on bulk samples of both high grade and low ore from Horn Island to assess the suitability of Tomra’s XRT systems to efficiently sort mineralised vein material from the barren granite host rock.
The results from the test work were considered highly successful with results indicating positive amenability to Tomra XRT sorting technology.
Strong gold grades were achieved across the two bulk samples with substantial mass reduction achieved at a high throughput rate.
Significant uplift of gold assay grades were returned for drill core samples, achieving up 392% increase with a significant mass reduction of up to 88%.
In addition, significant uplift of gold grades for waste dump samples achieved with a 463% increase in grade and a reduction mass of 89% and the waste product reject gold assay averages for resource drill core and waste samples were 0.21 g/t and 0.16 g/t respectively.
Improving project economics
Based on the nature of mineralisation, the company considered the Tomra method had significant potential to further improve the Horn Island Project’s economics.
Tomra Ore sorter results are considered material, with results being integrated into further metallurgical testing for inclusion into scoping studies as part of the future mining operations,
By removing waste rock before wet processing, the capital and operating cost of the project can be significantly reduced.
The company intends to update shareholders once metallurgical results are made available.