COMMINUTION AND CRUSHING
operations looking to utilise such a flowsheet , with Boylston saying the benefits go beyond simply reduced water use .
“ A lot of it comes down to water , but , for Iron Bridge , it also showed that the circuit could be more than 30 % energy efficient compared with a standard setup ,” he said . “ If you look at something at that scale and you are aiming for greenhouse gas and operating expense reductions , 30 % is a big chunk of your expenditure on a per tonne basis .”
Boylston says the company ’ s HRC™ HPGRs could also be factored into dry grinding applications where they are configured with a follow-on dry screening step .
“ A lot of HPGR circuits end up with a wet screening step , but if you are going to do it dry , you have to be very efficient because otherwise your screening area is going to be incredibly large ,” he warned . “ We have come up with HRC designs that incorporates such efficiency .”
When it comes to bringing down the energy intensity of grinding , the HRC HPGR and its latest iteration , the HRCe , continue to be spoken of in mineral processing circles .
The original HRC HPGR was launched back in 2014 by Metso ( now Metso Outotec ), pioneering the use of flanges and a non-skewing design , with a grinding performance that brought energy efficiency , lower circulating loads and increased throughput now strengthened with an additional evolution in design with the HRCe , Metso Outotec says .
The headline improved energy efficiency of up to 15 % in the HRCe is further aided by a lower circulating load of up to 24 % and the eradication of grinding media , translating to even more energy efficient mineral processing circuits and lower embedded carbon emissions than legacy technology , according to the company .
Metso Outotec is trying to facilitate further expansion of its Planet Positive comminution and crushing technology – which includes the HRC , HRCe and HIGmill , among others – through the modularisation and standardisation of key equipment .
Vauramo sees no reason why the company could not manufacture most of the plant in the factory environment , leading to reduced installation time and cost when on site .
This type of thinking is also coming into the company ’ s engineering and plant solutions group philosophy , according to Boylston .
“ A great example of that is the Vertimill ® ,” he said , referencing another Planet Positive solution . “ Between the product managers , my group and the plant solutions group , we have come up with modularised designs for Vertimill plant units that encompass the Vertimills , the pumps , the cyclones , the structure , etc .
“ The whole idea – whether it is one Vertimill , or several – is to have a lot of the engineering already done before any deliveries are made . You can still customise it according to your site , but modularising the process reduces the amount of time to go from engineering to order , and from order to start-up and making money for you in the plant .”
With the engineering for modularised Vertimills and horizontal mills complete , the next step is modularising HRCs , Boylston said .
While investors have focused on the financial synergies inherent with the Metso Outotec transaction – with € 142 million of annual run-rate cost synergies in 2021 alone – Boylston and his fellow engineers have felt the direct impact of having a much wider mineral processing offering .
He explained : “ Outotec came into the merger with a software package called HSC Chemistry and Metso came into it with a package called VPS ( Virtual Plant System ), and we ’ ve just finished a merging of those two systems . For me , as a process engineer , to be able to take the best part of VPS – which was energy-based comminution models and equipment selection – and merge that with HSC – which was all the downstream flotation , separation , filtration and the mineralogical modelling of the orebody – is fantastic .
“ By putting those together , we are able to look at designing a plant that is not just good for the average composite ore today , but that works for everything you will see in the next 30-or-so-years ahead , all with the ability to update that with daily or hourly inputs .”
The ability to connect these dots – from the dry end of the process that Metso previously focused and the wet end where Outotec ’ s solutions dominated – will continue to enable the company to provide its clients with full process visibility .
Creating a comminution legacy
Weir Minerals ’ ambition is to transform the mining sector ’ s sustainability credentials through replacing legacy milling technology with solutions that offer increased energy efficiency and potentially less water consumption .
Tim Lundquist , North American Enduron ® HPGR Manager , has been leading the drive in this region and has seen the company ’ s flagship Enduron HPGR solution gain in popularity over the last decade .
“ When I started working with HPGRs around 10 years ago , there wasn ’ t much of a market in mining ,” he told IM . “ You didn ’ t see many bid packages out there and there were not that many projects going on .”
Fast forward to today and Weir Minerals aspires to cross the 100-installation threshold in the next few years .
The ability to support increases in production while reducing energy consumption by around 40 % compared with alternative grinding solutions are the obvious benefits , and Lundquist was keen to highlight several others .
“ Over the last five years , we have become the market leader in coarse hard-rock grinding applications ,” he said . “ Every single project is unique and every single HPGR application is bringing reduced carbon footprints and efficiency savings , but I really like the brownfield projects where we are going into these existing operations and bringing them into today ’ s age of technology .”
Noting that a HPGR can find a home and bring an improvement in almost any operation around the world , Lundquist mentioned one brownfield industrial mineral application where the introduction of an HPGR resulted in the elimination of seven 50-year-old crushers .
He explained : “ We simplified their circuit , provided significant emissions reductions from taking seven crushers offline and replacing it with one HPGR , and also increased their product yield .
“ Historically , people don ’ t think about HPGRs as ‘ product creators ’, but they are actually well suited to creating products in certain applications and industrial minerals , in general , represents a massive growth market for HPGRs going forward .”
Lundquist also discussed the Iron Bridge project in Western Australia – referred to by Boylston above .
For Iron Bridge , Weir Minerals provided a full scale 2.2 x 2 m Enduron HPGR and air classification solution for the Stage 1 plant which was used to validate the complete process . More than 1 Mt were processed in this validation phase with the full support of Weir Minerals . The innovative dry comminution circuit was fully proven .
Weir Minerals is currently installing the dry comminution equipment for the full-scale Stage 2 of the plant . This includes six TRIO ® cone crushers , 12 Enduron HPGRs ( four 2.4 x 2.25 m units in the primary HPGR stage closed on dry screening and eight 2.2 x 2 m units in the secondary HPGR stage closed on air classification ) as well as 12 air classifiers and six product collecting baghouses .
Lundquist said of Iron Bridge : “ Taking an F80 of 80 mm and going to a P80 of 80 microns with HPGR and air classification , you ’ re biting off so much of your size reduction without the use of water . This is a ground-breaking project that will change mining and Weir Minerals is excited to be playing a leading role in it . Not only is it an ultraenergy efficient process , the dry comminution flowsheet means that a substantial portion of waste is removed from the process early and while it is still dry .
28 International Mining | APRIL 2022