REPROCESSING AND RETREATMENT
“ We have come up with a really neat environmental rehabilitation scenario where we fill the existing open pit up , and cap it all off nicely so the surface water cannot penetrate ,” he said .
Heritage is set to build a 2 Mt / y plant to reprocess this material , only looking five years out from first production . There is potential for this processing quantity to be doubled , though .
The DFS anticipates a one-year payback and an upfront capital expenditure bill of A $ 74 million ($ 57 million ). With a board decision on the DFS expected soon , Heritage could soon enter the financing stage , followed ( hopefully ) by construction . If all goes to plan , operations could begin in 2022 .
In the meantime , GreenGold has a team optimising the recently commissioned ReCYN plant at PT Agincourt Resources ’ Martabe goldsilver operation in Sumatra , Indonesia .
By far the biggest ReCYN installation of the technology , the plant , designed for active ( free ) cyanide reduction and detox applications to recover cyanide complexes such as copper , will fit into the 5.5 Mt / y circuit at Martabe , treating around 1.2 t / d of copper . It will also have benefits in terms of reduced cyanide consumption and improved water quality .
Recovering copper
Speaking of copper , Anglo American has recently approved the construction of a coarse particle recovery ( CPR ) plant at its in-development Quellaveco project in Peru , which could see tailings re-processed to bolster copper output .
CPR , Anglo says , is one of many significant breakthrough technology initiatives that has the potential to increase throughput and productivity , while simultaneously reducing environmental footprint , through rejection of coarse gangue ( near-worthless waste material ), dry stacking of sand waste , minimising the production of traditional tailings and reducing overall water consumption .
The CPR plant signoff at Quellaveco follows a full-scale demo plant installation at the company ’ s El Soldado mine in Chile – ramping up to full capacity by mid-2021 – and the decision to construct a full-scale system at the Mogalakwena North PGM concentrator in South Africa .
The El Soldado plant used the HydroFloat™ CPR technology from Eriez Flotation . Here , a single 5 m diameter HydroFloat cell , the largest in the world , treats 100 % of mill throughput , with the objective of proving the waste rejection process at full scale .
Anglo said of the Quellaveco CPR plant : “ This breakthrough technology will initially allow retreatment of coarse particles from flotation tailings to improve recoveries by circa-3 % on average over the life of the mine . This investment will also enable future throughput expansion
which will bring a reduction in energy and water consumption per unit of production .”
The capital expenditure of the CPR project is around $ 130 million , with commissioning of the new plant expected in 2022 .
Jetti Resources and its novel hydrometallurgical technology has been helping Capstone Mining recover copper from a dump leach operation at its Pinto Valley operation in Arizona , USA , previously consigned to waste .
This technology uses a catalyst on primary sulphide minerals to disrupt the sulphur metal bond of the mineral and allow for a leaching solution to contact the copper . This enables the extraction of the metal to take place unimpeded , extracting metals of value from mineral ores the mining industry has previously struggled to process .
Capstone is targeting to reach 60,000-63,000 t average daily throughput at Pinto Valley at an 85- 90 % recovery by 2022-2023 with the help of this technology . This is 17-30 % higher than 2019 performance and is subject to further test work and studies to be completed in the first half of 2021 , the company explained .
With mill throughput already reaching 60,717 t / d in December , which represents a new monthly record , the company continues to have confidence in a projection that it will recover up to 350 MIb of copper cathode over the next two decades from historic and new mineralised waste piles using Jetti ’ s technology .
Capstone is also weighing up the use of Eriez ’ s HydroFloat CPR technology having conducted a pilot plant test using the solution at Pinto Valley in December . Capstone said the results had surpassed expectations of a 6 % improvement target to overall copper recovery , with a 6-8 % increase achieved .
Increased optionality
Having successfully recovered chrome concentrate from a combined hydro and mechanical re-mining method that uses magnetic separation , Barplats Mines is now setting its sights on adding platinum group metals to the mix .
Eastern Platinum Ltd , which owns Barplats Mines , says the technology it has developed to process tailings at its Crocodile River Mine property in South Africa can obtain superior yield results compared with traditional gravity technology .
In early-March , Eastern Platinum confirmed the operation , in 2020 , mined some 2.33 Mt of tailings for 987,003 t of chrome concentrate production . This came with a yield ( wet ) recovery of 37.47 %.
The company is currently reconfiguring and optimising the small-scale platinum group metal circuit ( previously the scavenger plant circuit ) at
the operation , which also includes funding for some of the initial work required to restart the main PGM plant circuit .
Barplats previously entered into an agreement with Advanced Beneficiation Technologies Proprietary Ltd of South Africa to complete an independent feasibility study for the development and construction of a new modular plant with a capacity to process the PGMs from the tailings redeposited from the Retreatment Project at a designated area of the Zandfontein Tailings Dam at an expected rate of 50,000 t / mth . This project is looking at remining the tailings already deposited from the beginning of the Retreatment Project to extract additional value from PGMs . The results from the study are expected shortly .
Neo Performance Materials and Energy Fuels Inc , meanwhile , have recently announced a new rare earth production initiative spanning European and North American critical material supply chains .
The initiative is set to produce value-added rare earth products from natural monazite sands , a by-product of heavy mineral sands mined in south-eastern USA . It will see Energy Fuels process the monazite sands into a mixed rare earth carbonate in Utah , USA , for use as feed material for Neo ’ s value-added separated rare earth production plant in Europe .
Energy Fuels has already begun processing natural monazite sands into a rare earth carbonate at its White Mesa Mill as part of the agreement , and is set to ship a portion of that production to Neo ’ s rare earth separations facility in Sillamäe , Estonia , shortly . Neo then intends to process the carbonate into separated rare earth materials for use in rare earth permanent magnets and other rare earth-based advanced materials .
Energy Fuels processed monazite at a pilot scale last year using existing equipment and circuits at the 8 MIb / y-plus capacity mill .
Still in the US , Rio Tinto recently confirmed it will construct a new plant to recover tellurium , a critical mineral used in solar panels , from copper refining at its Kennecott mine near Salt Lake City , Utah .
The company is investing $ 2.9 million to set up the plant , which will have a capacity to produce around 20 t / y of tellurium , the miner said .
Rio expects to begin production of tellurium in the December quarter of 2021 , creating a new North American supply chain for the critical mineral .
Rio Tinto Kennecott Managing Director , Gaby Poirier , said : “ Adding tellurium to our product portfolio provides customers in North America with a secure and reliable source of tellurium produced at the highest environmental and
APRIL 2021 | International Mining 55