COMMINUTION AND CRUSHING
“ The Pilot modular offering means there is no need for lengthy bespoke design timelines and a complete plant layout and process simulation flow can be completed within a few days ,” Francois Marais , Director of Sales and Marketing , told IM .
These modular units are kept in stock and plants up to 500 t / h can usually be supplied within two-to-four weeks from commercial finalisation , according to Marais .
“ We see the Pilot Modular offering as being a compelling argument in favour of making a departure from the traditional approach to project timelines and planning for a much faster , more predictable approach to getting projects into the production stage faster ,” he said .
Fred Bradner , Vice President of Strategy of Sales , Marketing and Communications at Weir Minerals , says the mining industry ’ s commitment to energy and water efficiency has strengthened during this most recent 12-18 month period .
“[ This ] shapes Weir Minerals ’ research and development strategy , so our focus has been firmly on the sustainability agenda ,” he told IM . “ At the same time , we are still cognisant of the fact that these improvements must not be achieved at the cost of throughput and productivity for our customers .”
Weir says it has been able to find this balance by building flowsheets designed around its Enduron ® high pressure grinding roll ( HPGR ) technology .
“ Apart from not requiring water , HPGRs use up to 40 % less energy than traditional semiautogenous grinding ( SAG ) mills and , while they can ’ t always be a 1:1 replacement of a SAG mill in terms of throughput , several machines can be deployed to cost effectively replace SAG mills ,” he said . thyssenkrupp Industrial Solutions personnel responded in a similar manner when asked about the common issues / concerns it has been receiving from its mining clients in designing and maintaining comminution circuits .
“ The medium-term goal is to become more environmentally friendly by a reduction in energy consumption , greenhouse gases and water consumption ,” Matthias Goeing , Director of Product Lines Mining Technologies , told IM .
He said “ game-changing , innovative , or revolutionary ” flowsheet designs were required to meet this goal , all while rationalising the capital expenditure required to deploy and maintain such solutions .
“ Dry HPGR fine grinding could turn out to be such a green solution if potential ‘ show stoppers ’ like elevated capital expenditure and feed moisture limitations can be overcome in the future ,” Goeing said .
In the short term , Goeing said customers were looking to improve the economics of new “ lowgrade ” projects by evolving the use of existing processes and equipment , while overlaying digital tools to maximise circuit capacity and availability and produce more tonnes from current operations .
Safety , reliability , optimisation , early problem recognition and notification , and longer-term trending and prediction for more efficient asset management are the main challenges FLSmidth mining customers identified over the last yearand-a-half , according to Bill Malone , Global Product Director , Crushers , and Sven Hoerschkes , Head of GPLM , Construction and Feeders .
The company has reacted to this with several new developments in its primary gyratory crushing line worth exploring in more detail .
Prime crushing
The drill and blast engineers would rightly argue the comminution process starts in their area , but , for the purpose of this discussion , we will begin at the primary crush stage .
There are a few options to slot into this spot in the flowsheet , but there has been a prevalence – especially with large throughput operations – to favour primary gyratory crushers .
These machines , which receive run-of-mine material directly from the mine itself , typically crush the rock down to a maximum of about one-tenth of its size . Being front and centre of the comminution process , the primary gyratory crusher ’ s performance has a bearing on all the other follow-on processes in the flowsheet .
As a result , throughput and availability are often key elements considered when deciding on which primary gyratory to use .
“ Most medium-to-large-size mines continue to use / specify gyratory crushers and , with the
thyssenkrupp ’ s next-gen primary gyratory crusher is being lined up for installation at the jointly owned Iron Bridge magnetite project , in Western Australia
decline in ore deposits , the emphasis is on much larger machines that can handle increased capacities in order to compensate for the lower ore grades ,” Malone and Hoerschkes told IM .
“ In general , once average capacity rises above 1,800 t / h , then a gyratory crusher will be specified ,” they added . “ Below this figure , there is the option of using jaw crushers to achieve the same result .”
Frank Drescher , Head of Crushing Technologies at thyssenkrupp Mining Technologies , says he sees an expanded use of primary gyratories across the mining space – not just at large mine sites – with the operating cost , product quality , product lifespan , and throughput and availability winning out against other options . thyssenkrupp ’ s next-gen primary gyratories are being lined up for installation at the jointly owned Iron Bridge magnetite project , in Western Australia . This follows the company ’ s first aboveground large gyratory installation in Australia at the Roy Hill iron ore mine , also in the state , in 2019 .
Metso Outotec ’ s Head of the Crushing business line , Guillaume Lambert , broke down the mining OEM ’ s crushing customer base to emphasise the sector ’ s primary gyratory crusher uptake .
“ Ninety percent of the large mining operations are using gyratory crushers in the primary stage ,” he said . “ While the capital expenditure is higher for these solutions , it is outweighed by a lower operating expenditure and higher availability .”
12 International Mining | APRIL 2021