Recoveries of 95.3% were achieved from testwork involving Brolga mineralisation, with the advantages of the Albion process said to include capital and operating costs, flexibility and simplicity. 

In addition, the process entails atmospheric leaching and low pressure oxygen tank. 

"However, metallurgical testwork and studies remain at an early stage and POX, Albion and BIOX oxidation processes all remain under active consideration for use at Hemi," De Grey said. 

The company also said open circuit primary crushing followed by a SAG mill with pebble crusher and ball mill was looking a potential comminution route. 

De Grey has been targeting a maiden resource estimate mid-year. 

Shares in De Grey were down 1.7% to A87c, capitalising the company at $1.1 billion.