The first of four autoclaves at the operation has now been put through hot commissioning, and its first refractory ore concentrate processing was scheduled for November 28.

The concentrate loading, re-grinding and lime preparation sections have also been commissioned, with first concentrate and limestone being loaded now into the plant ahead of the autoclave commissioning.

Petropavlovsk officials said the oxygen plant has been fully commissioned and is currently being prepared for oxygen production to start; that will supply autoclave 1 once refractory concentrate testing begins this week.

At this time, the miner said its target for maiden gold production from the POX plant ‘shortly' remains on track, and it anticipates ramping up to sustainable commercial production throughout 2019. The POX hub is projected to produce about 500,000oz/y of gold.

"The POX operations are the key to unlocking the significant value embedded in Petropavlovsk, partly contained in our 9.6Moz of refractory gold resources in highly prospective, easily accessible, low strip deposits," CEO Pavel Maslovskiy said.

Petropavlovsk's Pioneer, Malomir and Albyn gold mines, as well as the Pokrovskiy and Blagoveschensk processing and research and development facilities, are all located in the Amur region of the Russian Far East.