Novo Resources has announced gold-rich assay results from concentrates generated by mechanical sorting trials conducted on four bulk samples from its Karratha gold project in Western Australia.

In order to test the potential viability of mechanical rock sorting as a means of concentrating gold from conglomerates at Karratha, four bulk samples were collected, crushed, screened and tested using a TOMRA mechanical rock sorter. High-grade assays from sorted rock concentrates have provided a first indication that this technique is effective at upgrading gold into small volume concentrates.

Mechanical sorting was conducted on material ranging from 6 to 63 mm. Fractions larger than 63 mm and finer than 6 mm are currently undergoing assaying and, once all analyses have returned, an assessment of the effectiveness of mechanical rock sorting will be made, Novo said.

Mechanical rock sorted concentrates range from 0.07-0.48% of total sample mass, a remarkably small fraction. Given the high-grade assays of these concentrates, ranging from 92.1-792.4 g/t Au, it appears gold is being significantly upgraded by mechanical rock sorting, the company added.

“Optimising crushing to reduce volumes of fines and oversize, effectively maximising the amount of material being sorted, should further improve the potential of this technology,” Novo said, adding that mechanical sorting technology could be a critical component of the Karratha gold project moving forward.

Rob Humphryson, CEO and Director of the company, said: “Concentrate grades received from the recent TOMRA mechanical rock sorting trials are impressive, reflecting the capability of the scanning and sorting technology to differentially select gold bearing rock.

“Total system gold recovery efficiency will be fully understood upon receipt of assay results from all process streams and feed size ranges, with these results expected during January 2019.”