They are unable to extract the barely-visible gold from ore brought to the surface for processing. But mine owner Mandalay Resources has vowed to change that.

It will partner with company Eriez to build two eight metre tall flotation tubes capable of separating gold from crushed-up rock.

Costerfield miners will pour a slurry of mine tailings and water into the tubes at their Costerfield processing factory.

Gold will float to the top and fall over the lip of the tubes as water cascades out.

Mines often use flotation to separate gold from slurry but the equipment used is usually box-shaped and unable to get anything as small as 30 microns.

A human hair is generally about 40 microns in diameter and many fine sands are about 60.

Miners have spent centuries figuring out new ways to get gold out of mine tailings.

Many people made a tidy living combing mullock heaped near mine shafts dug during the 19^th century's Victorian gold rush.

Mandalay plant manager Paul Omizzolo said modern-day techniques can remove as much as 90 per cent of the gold brought to Costerfield's surface.

"Some particles are too small or are compounded with other minerals that don't want to float," he said.

"So you are always going to have some gold you are not going to be able to recover. Ninety per cent is usually a good amount to get."

Miners spent last month testing temporary tubes in Costerfield. They now believe they could double the amount of gold they can take from the "final tail" of ore that comes out of their processing plant.

It would mean that at least 93 per cent of gold of all the gold they dig up could be extracted from the ore.

It comes at a time as miners dig deeper into the "Youle vein", a massive underground gold field that lay undiscovered until 2017.

They are moving into the new field after largely exhausting nearby gold deposits.

Mandalay plans to retrofit its processing plant and expects to take delivery of new tubes by about October or November.

The company revealed its tube plans in its latest quarterly report to shareholders. The report also showed Costerfield miners dug up 13,502 equivalent ounces of gold and sold 933 tonnes of antimony over last three months.

Fosterville miners also had a good quarter, Kirkland Lake Gold's quarterly report shows.

They produced 155,106 tonnes of gold, a 10 per cent increase on the same period a year ago.