Toronto-listed Granada Gold Mine thinks pre-concentration by separation has the potential to lower capital and operating costs at its Granada gold project in Rouyn-Noranda, Quebec, Canada.
The company has come to this conclusion after receiving higher grades during testwork, which, it said, “may have implications for the grade of future mill feed, the size of the gold deposit, and the costs associated with future mine production.”
The company went to Gekko Systems of Ballarat, Australia, for this testwork. Granada said of Gekko: “Their innovative pre-concentration system increases recovery values, reduces ore mass and waste, reduces water use, lowers power requirements, and improves feed rates, all potentially meaning lower capital and operating costs for Granada along with higher recovery rates.”
A 260-kg sample of low-grade drill core assaying 0.6 g/t was upgraded to 6 g/t with a 60% overall recovery by this work. The Gekko laboratory processed the sample by crushing through different size fractions, homogenised, and split according to standard lab practices, Granada said. Gravity tests were conducted on coarse and fine fractions, approximately +600 μm and -150 μm, respectively.
A grade of 21 g/t Au was achieved from the coarse size fraction, with a recovery of 40%, resulting in an upgrade ratio (concentrate/feed) of 35.
Frank Basa, Chairman and CEO of Granada Gold, said: “As a result of this preliminary work, we believe that employing disruptive technologies on lower-grade ore to pre-concentrate the mineralised material for process plant feed can be advantageous. This approach can be used to evaluate the potential to increase the gold resource and other recoverable metals which, in turn, will lower project capital and operating costs.”
In a related matter, the company has also begun a test programme using the pilot plant of its sister company, Canada Cobalt Works. In this first round of tests, a 120-kg sample of low-grade mineralised rock from the Granada gold mine waste dump was processed by screening the material into three screen sizes followed by gravity separation. These concentrates were then analysed for gold, silver, cobalt, nickel, and copper.
Gravity assay test results are pending, with a particular focus on recoverable base metals.
The current feasibility study for the on-site gold mine and plant at Granada has been put on hold pending results of the metallurgical studies. The environmental studies to install a 600 t/d gravity leach plant are, in the meantime, ongoing at the Canada Cobalt Works Castle mine. The flowsheet has been completed and equipment has been sourced, the company said.
The company is in possession of all permits required to commence the initial mining phase, known as the “Rolling Start”, which allows the company to mine up to 550 t/d, capable of producing up to 675,000 t of ore over a three-year period.