COPPER PROCESSING
Integrating vertical stirred grinding mills from Swiss Tower Mills Minerals into Weir Minerals ’ Enduron HPGR-backed minerals processing flowsheet will provide customers substantial improvements in throughput and energy efficiency , according to Weir Minerals
This technology – which Weir Minerals has access to through a cooperative agreement to design and develop CPF systems with Eriez Flotation – further increases throughput , as well as having sustainability benefits
“ Not only does it reduce energy consumption ; with maximum production of coarse reject material , the ability to manage tailings is vastly improved ,” Dierx said . “ The coarser tailings PSD improves water drainage and can reduce tailings impoundment size , thereby minimising environment risks .”
A recent process optimisation study for a mining company looking to increase the capacity of the base case copper concentrator with an SABC ( SAG-ball mill-crusher ) circuit from 12 Mt / y to 27 Mt / y highlighted these benefits .
Several iterations of SABC and HPGR circuit designs were reviewed to better understand the opportunities to reduce operating and capital costs , as well as provide greater operational flexibility . Furthermore , the study sought to provide the expected return on investment of the HPGR and ball mill circuit during the ramp-up phase of the greenfield project .
Weir Minerals Enduron ® HPGR-based circuits were found to have lower capital costs than the SABC-based circuits , reducing the miner ’ s anticipated capital expenditure by around A $ 100 million ($ 69 million ), according to Dierx .
Further , in terms of operating costs , the HPGRbased circuits demonstrated a reduction in operating power requirements by around 6-9 MW , compared with the SABC circuit equivalent . And the addition of CPF reduced energy consumption by around 6-10 MW for both circuits .
“ In addition to the poor energy efficiency of the SABC circuits , operating costs were also higher as a result of increased grinding media consumption , which has a high carbon footprint resulting from embodied energy ,” Dierx said . A single-train HPGR circuit with CPF was forecasted to reduce processing costs by up to A $ 1.23 / t of ore and reduce power demand by up to 19 MW when compared with the base case SABC circuit . Moreover , water consumption was also reduced by around 1.8 gigalitres per annum . The Enduron HPGR has a number of unique features that are instrumental in delivering these results with unrivalled circuit availability in industrial applications , according to Dierx .
“ Traditionally , HPGR manufacturers have opted against skewing designs for fear of roller misalignment creating unfavourable load distributions and preventing the use of flanged guards to reduce the edge effect ,” he said . “ However , the Enduron HPGR ’ s unique roller bearings design allows for skewing alongside effective self-adjusting cheek plates , reducing wear and promoting better grinding .”
Another feature of the Enduron HPGR is the protective bearing arrangement that ’ s been designed to guard against premature failure and reduce the number of peak loads transferred to the bearings . Enduron HPGRs are supplied with a multi-row cylindrical roller bearing system and a
Weir Minerals tailored rubber thrust pad arranged directly in front of the bearing housings . This ensures the bearings are always parallel with the shaft , mitigating the peak pressures and bearing contamination . It also allows for oil lubrication to the main bearings , which delivers leading bearing life with proven performance guarantees in excess of 100,000 hours , Dierx added .
He concluded : “ OEMs like Weir Minerals have a vital role to play in developing and delivering technologies and equipment that help miners achieve their lofty GHG targets – it ’ s through these partnerships that the transition to a low carbon economy will be realised .”
Pushing through an open door
For a mining operation , after extraction and haulage , crushing and grinding is where most emissions are generated , according to Oliver Guyot , VP Minerals Technology at Metso Outotec .
The mining OEM has plenty to offer in terms of reducing the energy consumption associated with comminution – its portfolio of stirred mills
A combination of Metso Outotec Planet Positive solutions – not just individual items – can provide the compounded impacts the mining industry needs to meet its 2030 , 2040 and 2050 goals , the company says
16 International Mining | MARCH 2023