COMMINUTION AND CRUSHING
He is confident these attributes and an evolving need to reduce emissions and water use will see HPGRs and other mineral processing equipment combined in more advanced grinding circuits going forward .
“ The use of an HPGR can be seen as catalyst for more creative comminution circuits ; it is all about pairing the machine with other solutions within a system ,” he said . “ This could see the Enduron HPGR growth continue when used alongside air classification processes or stirred mills , for instance .
“ Our continued aim is to take as much of the legacy milling technology out of the mining sector as we can .”
Saving money , energy , water and resources thyssenkrupp Mining Technologies considers itself a frontrunner in introducing new comminution technologies into the mining sector , with a host of innovations gaining acceptance and traction across the industry .
“ It was quite a journey to get acceptance for the HPGR as a more sustainable alternative to conventional solutions in terms of process efficiency , product quality , energy consumption and wear part consumption ,” Jürgen Remmers , Head of Product Line Grinding , told IM . “ As the market leader for HPGRs in the mining industry for almost 40 years , thyssenkrupp has over 150 installations worldwide with the majority in hardrock applications . In in the last six months , alone , our clients have ordered 15 new large HPGRs .”
The key to a successful HPGR industry introduction was to bring the wear surface of the roll tyres to industrial maturity , according to Frank Schroers , Product Manager / HPGR .
“ In hard-rock applications , lifetimes above 12,000-15,000 hours are generally achieved .”
The next level of digitalisation was implemented in the next-generation HPGR Pro series to exceed these lifetimes and contribute to better usage of resources , Schroers says .
“ The laser-based stud detection system allows the operator to monitor the wear surface during operation and schedule wear surface maintenance only if needed ,” he said . “ This makes the operation ‘ smarter ; and reduces costs as well as the risk of unscheduled downtimes .”
Thomas Mackert , Head of Grinding Process Engineering , added : “ The AMPS ( advanced machine protection system ) uses digitalisation to accomplish the concept of predictive maintenance and optimised operation of the machine . The fast and accurate sensor technology in the proprietary AMPS enables process and machine data to be collected much more precisely .”
The system also detects critical operating conditions early enough for the required adjustments to be made – all with the goal of optimising processing technology and achieving trouble-free HPGR operation with lower production costs .
“ Moreover , with these implemented features , plant operators can now , at their choice , rely on the online know-how and speedy assistance of remote thyssenkrupp experts ”, Mackert said .
Besides digitalisation , the new HPGR Pro has several innovative features , according to Schroers .
“ The wealth of experience and the feedback obtained from customers in widely varying applications all over the world led to the development of innovative features in this upgrade to the HPGR , the HPGR Pro , which we released in 2020 ,” Schroers said .
“ The use of rotating flanges ( aka flanges ) on the fixed grinding roll , instead of cheek plates at
Communition and energy today
By Eric Wasmund , Eriez ® Vice President Global Flotation Business ; Jose Concha , Global Product Manager HydroFloat ® ; and Asa Weber , Global StackCell ® Product Manager
As has been documented , companies are looking at improving the efficiency of comminution , as well as minimising the extent of grinding required .
New technologies are being studied today that channel energy more selectively such as novel blasting techniques , microwaves or dry grinding . At the same time , technologies such as real-time ore sensors are being studied because they allow gangue to be rejected ahead of the energy intensive process of comminution . This approach is being used at the mine face as well as inside the concentrator . In fact , separating gangue in conventional flotation is the least energy efficient way to do this , since the amount of invested grinding energy is very high after the particle size distribution has been reduced to the size range for conventional flotation . Another approach is to use coarse particle flotation ( CPF ) as the prerougher to separate ore from gangue while the size of particles is two-tothree-times coarser than the feed preparation for conventional flotation : this application is called coarse gangue rejection ( CGR ). Because grinding efficiency decreases and energy increases as the particles become smaller , CGR , in this range , can significantly reduce the size , energy use and capital and operational costs of grinding circuits .
CGR is only feasible with a coarse particle flotation technology , and the only commercial offering is the Eriez HydroFloat , a novel fluidised bed flotation device that enables semi-liberated ore to be recovered at a much coarser size than conventional flotation . Commercialised in other applications almost 20 years ago , the HydroFloat technology in a CGR application is installed inside a conventional mill circuit allowing to reduce over-grinding by continuously removing coarse barren tails that by-pass the conventional flotation circuit . It also has the benefit of producing part of the flotation tails in a more stable and benign format . In a recent benchmarking study presented at the 59th Meeting of the Conference of Metallurgists , it was estimated that the HydroFloat CGR application could reject 30 % of the total mass of the mill feed as coarse barren tails , allowing an estimated reduction in ball mill grinding energy of 30-50 % and an estimated reduction in conventional flotation capacity of 40 %.
In a vendor-operator collaboration , a HydroFloat CGR plant has been implemented on a commercial scale at a copper concentrator and another installation will be commissioned later this year . This installation has allowed the evaluation of practicality , stability and maintainability of the HydroFloat CGR application using the largest commercially available HydroFloat , the CPF-300 . More results will be reported later this year , but the benefits of energy and water savings , metallurgy efficiency as well as tailings stability , all make this a technology innovation that can improve the sustainability and profitability of mining .
In a recent study , it was estimated that the HydroFloat CGR application could reject 30 % of the total mass of the mill feed as coarse barren tails , allowing an estimated reduction in ball mill grinding energy of 30-50 % and an estimated reduction in conventional flotation capacity of 40 %
32 International Mining | APRIL 2022