COMMINUTION & CRUSHING
circuits Fluor is developing not only save owners costs and reduce maintenance time , they also shrink the environmental footprint of the operation as well , Sherman said .
Fluor and joint venture partner Petrosea – through the Fluor Petrosea Joint Organisation – have previously worked on a project to install a new grinding mill in Papua , Indonesia
impact the performance of the ball mill . Then there are stirred mills of all sizes to consider , with power ratings on this equipment having doubled over the last 10-15 years , going from 3.3 MW to 6.5 MW .
Interest in stirred mills is increasing as they offer lower media consumption rates than ball mills , while consuming approximately 20-35 % less power than a ball mill to achieve the same product size , depending on the grinding duty ( secondary grinding and concentrate regrinding duties , respectively ), Sherman said .
In recent projects and studies , the combination of reduced power and grinding media consumption rates significantly reduces the carbon footprint of a stirred mill circuit compared to the traditional ball mill operating in closed circuit with a hydrocyclone classifier , according to Sherman . Fluor concludes that the stirred mill is a superior grinding option for the project and or study team ’ s consideration .
In direct comparison with a traditional circuit , Fluor has quantified the benefits of a stirred mill producing fewer slimes , which will become more important as the head grades of deposits continue to fall and the host rock becomes harder . Overgrinding of the target minerals has a detrimental effect on flotation circuit performance due to more of the target mineral being lost to tailings , and a reduction in flotation kinetics , which reduces the grade of the material reporting to the regrind and cleaner circuits .
Some operators recognise grinding media costs as a major component of their milling costs , which has led them to investigate the use of vertical roller mills ( VRMs ), which do not use grinding media , as their preferred choice of comminution technology .
The newest VRM installation , for a 10-12 Mt / y flotation concentrator , is currently in the final stages of design .
Like stirred mills , the challenge for VRM technology will be to supply large-capacity machines to meet the future needs of the industry , Sherman said .
Given the broad range of stimuli imparted on the minerals industry – ie rising power , construction , and consumable costs , falling head grades , the need to process harder ores at higher capacity while reducing the operation ’ s carbon footprint , etc – the future of the comminution industry is ready for another era of changes , Sherman said .
“ Some industry practitioners are pursuing HPGRs feeding stirred mills as the ‘ circuit of the future ’, while others pursue VRMs as a low operating cost alternative ,” he said . “ Owners of large tonnage , eg plus-150,000 t / d circuits , will still find a place for large diameter grinding
mills due to their relatively low installation costs , higher utilisation rates , and the potential for further improvements in power efficiency and reductions in operating costs , achieved via the implementation of synergistic technologies .”
As the complexities in factors impacting comminution studies grows , the completion of a thorough trade-off assessment during the study phase is critical . The highly efficient comminution
Closing in on the MissionZero Mine
FLSmidth , fresh from its acquisition of thyssenkrupp ’ s Mining division , is bringing a process-first and full-flowsheet perspective to any crushing and comminution discussions it has with mining clients .
“ This ranges from selecting the right equipment for the application ( eg dimensioning and capacity , operational and performance requirements , etc ) to technology upgrades and retrofits ( eg newer , more advanced equipment models ),” the company told IM .
FLSmidth has had its MissionZero aims in place since November 2019 . These centre on an ambition to provide zero-emission technology to the mining and cement industries by 2030 , enabling a potential 10 % reduction in the world ’ s CO 2 emissions .
The company sees the recent expansion of its
As is discussed throughout this article , the protection of SAG mills is an important part of achieving immediate energy-efficiency gains for mining companies . Mill liners – whether they are metallic or made up of some sort of hybrid material – are relied on for this , offering increased equipment uptime .
ME Elecmetal recently achieved a significant increase in wear life of shell liners at a SAG mill operation it had an existing relationship with .
After the customer approached the company with a desire to improve the life of its SAG mill casing liners , ME Elecmetal – the sole supplier of these liners since the SAG mill was commissioned – came up with an alternative solution . The goal was to match the life of the liners to the life of the head liners , in addition to reducing the number of liner change-outs performed during the year .
Dulguun Erdenedorj , Account Manager Eurasia , explained : “ All mills require unique design solutions based on their operation parameters and ore characteristics . Our role is to find the most optimum design solution for that specific equipment without compromising the operational parameters and customer requirements .”
After proposing several options , ME Elecmetal technicians and the customer settled on a change to the use of the WS-170FP alloy , from the WS-140 alloy previously used ; the installation of a thick plate in the high-wear area of the lining ; and removal of part of the materials from the low-wear area to reduce the final weight and remain within the 2,500 kg capacity of the liner manipulator . The results speak for themselves . The original shell liners worked for 137 days , with 91 % mill availability . Over that period , 3.28 Mt of ore was processed .
The new liners worked for 158 days , processing a total of 3.78 Mt of ore , implying a 15 % increase in the wear life – which the client was looking to achieve – and the amount of processed ore , ME Elecmetal said .
crushing and comminution product offering with the incorporation of thyssenkrupp ’ s Mining division potentially accelerating these aims .
“ This is because the acquisition strengthens FLSmidth ’ s position in HPGR applications and expands our installed base and offering , opening up opportunities for dry finish grinding and new equipment , such as the ERC ® Eccentric Roll Crusher ,” it said . The ERC , released in 2019 by tk Mining , fits into FLSmidth ’ s range of jaw crushers
SEPTEMBER 2023 | International Mining