Abstract: A gold mine adopted a heap leaching process but the gold leaching rate had been low. No evident improvement was made when a full-ore cyaniding leading process was tested. A process mineralogical study was thus made and it was founded that it is mainly realgar and orpiment that affect the gold leaching. Based on this result, a test was made, in which the run-of-mine ore was first treated by flotation to remove the sulfides such as realgar and orpiment, and the flotation concentrate was treated by cyaniding leaching after a pre-treatment while the flotation tailing was directly fed to cyaniding leaching. The total gold leaching rate reached 88.52%, an increase of 25.02 percentage points compared with that of direct cyaniding leaching of run-of-mine ore.

Key words: Gold ore, Process mineralogy, Realgar, Orpiment, flotation, Cyaniding leaching