COSTERFIELD miners are missing ultra-thin slivers of gold half the size of some of the finest grains of sand.
They are currently unable to extract the barely-visible gold from ore brought to the surface for processing.
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.
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 19th century miners spent gold rushes combing mullock heaped near mine shafts.
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 and 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 quarter a year ago.
Booming production came at a good time for Kirkland Lake, which was forced to temporarily suspend some of its diggings in Canada because of the spread of the coronavirus.
Fosterville or Costerfield mines' escaped major disruptions last quarter despite two waves of coronavirus outbreaks.
Health Authorities were yesterday tracking five active coronavirus cases, including three in Bendigo, one in the Macedon Ranges and one in the Loddon Shire.
That does not include the Mitchell Shire, where authorities were tracking 11 active cases yesterday.
Police have been blocking roads from Mitchell Shire into areas including Fosterville and Costerfield under a new Melbourne lockdown that started last week.
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