Aim-listed Cora Gold says the results of its latest metallurgical testwork on oxide samples recovered from the Sanankoro gold discovery, in Mali, continued to yield an encouraging characteristics profile for the processing of oxide gold.

About 207 kg of oxide material was tested by Wardell Armstrong International from the Selin, Zone A and Zone B prospects of the discovery.

Cora reports that the more competent sap rock, derived from deeper in the weathering profile, is characterised as very soft on the crusher, abrasion and rod mill work indices, and medium on the bond ball mill index.

In whole-ore leach tests, all the lithological groups reported gold recoveries ranging between 95.4% and 98.3%.

Additionally, testing for environmental characteristics confirmed that the leach residues were neither avid-generating nor carrying toxic elements at hazardous levels. 

The company continued a column leach test over 95 days, which so far recorded gold recoveries of about 56%.

“The results from this comprehensive scoping study-level of metallurgical testwork on a variety of oxide ore types and depths at Sanankoro has continued to yield a very encouraging characteristics profile for the processing of oxide gold. 

“The confirmation that the oxides are soft and will require only moderate grinding to a relatively coarse grind size, with only modest concentrations of cyanide and yet still able to generate gold recoveries well in excess of 90%, is particularly welcome. This points to the potential for a lower-cost processing route, which, in conjunction with anticipated lower mining costs, should help to support the ongoing scoping study,” comments CEO Jonathan Forster.

Although gold recoveries from the column leach do not match that of the cyanide leach approach, it is reassuring that the result obtained is considered a minimum with further upside potential if a programme is pursued over a greater length of time, the company says.

This work shows that heap leach, with expected lower capital expenditure, may still be considered as an option.