The second stage of L&M Mining's operation, it would begin "after the bugs are ironed out" of the plant, mine manager Mark Coleman said.
The plant, which is floating in 3m to 4m of water, weighs 850 tonnes when loaded and measures 12m by 30m.
"It has been totally upgraded, with about $3 million spent on it.
"It's still being tested at the moment but we're doing our final testing now and it should be operating full-scale within a couple of weeks," Mr Coleman said.
"It was a scaled-down version of this, used to get all the systems in place, but once this plant is under way, it's the full-scale operation - up a cog."
The Earnscleugh project is one of the largest alluvial gold-mining operations in the country.
Although he was not prepared to divulge how much gold had already been extracted, Mr Coleman said the volume "has lived up to our expectations".
The company earlier said it expected to get about 110,000oz of gold from the 150ha of Earnscleugh property.
At yesterday's spot gold price, the total haul was worth $235 million.
Mining has been round-the-clock since June last year.
Twenty-one staff were employed but that number would rise to a peak of 40 within the next eight months, Mr Coleman said.
"All the employees are local and all the contractors working on the project are locals as well." L&M told a business forum in Alexandra in May it was spending $10 million a year in Central Otago for the next six years through the mining operation.
Mr Coleman said the new plant would process 150cu m of gravel every hour.
At the end of the process, the fine gravel which contained the gold was taken to another location to be screened to retrieve the gold. The plant moved along as it completed an area. "We dig in front of it and it fills behind it."
The majority of the 150ha to be mined was farmland, and 14 million cu m of gravel wash and 32 million cu m of overburden would be processed. Both were gold-bearing gravels, with the wash containing a higher concentration.
Three people worked inside the gold recovery plant, which housed a control room and a "smoko" room.
The remainder of the mine crew was made up of drivers, staff stripping soil off the next area to be mined, maintenance staff, auxiliary workers, management team and those working on rehabilitating the mined land.
No decision has been made yet on the final use of the land, but it would be "improved farmland", Mr Coleman said.
Resource consents granted by the Central Otago District Council and Otago Regional Council contained 132 conditions and regular noise, air, dust and water monitoring was carried out.
