COMMINUTION & CRUSHING
more use of renewable energy .
This is where the ability to scale to the demands of the operation , both up and down , will hold mining equipment operators in good stead . Such flexibility could allow for operators to , for example , process harder material when solar irradiation is highest in the day and softer material at reduced throughput rates after solar generation peaks .
While this evolving operating context – seen already in the likes of Australia and South America – is recognised in the development of Metso products , and the company sees the importance of that capability increasing in applications using mostly renewable energy , some of its products are constrained by design architecture meant for consistent operation . Knorr expanded on this : “ Crushing and screening equipment is inherently compatible with intermittent operation and the crusher capacity can be scaled with the use of variable speed drives ( VSDs ) in some duties . Likewise , grinding equipment very often utilises VSDs to increase the available turndown ratio .
“ That said , this type of capital-intensive equipment provides the best return on investment when operated at full capacity and the highest potential utilisation , so development of stable power systems that utilise renewable energy will be an important area of development for the industry .”
Should mining companies look to apply bulk sorting at coarser size fractions , one would expect there to be an opportunity to bring down this overall processing power requirement . It would also open the door to multi-stage crushing and screening integrated with sorting , which , as Knorr commented , is more compatible with intermittent operations .
This type of thinking is being used further downstream of comminution in the flotation space , as Antti Rinne , Vice President , Flotation , acknowledges .
“ As coarse particle flotation becomes more prominent within grinding circuit flowsheet designs , this will increase the demand for high efficiency grinding equipment for secondary and tertiary grinding circuits ,” he told IM , referencing a major trend in the flotation sector .
“ Pumping , classification and dewatering will also require unique solutions for these circuits and those operations are compulsory for the coarse particle flotation technology currently available at industrial scale ,” he added .
This is where Metso , as a solution provider able to provide the equipment to pump , classify and dewater coarse particles , can facilitate integrated flowsheet designs that enable high mineral recoveries at such fractions , reducing the grinding requirements – and therefore energy requirements – further upstream .
“ Unlike fine particle recovery where you can tweak levers in the flotation process to increase the recovery of fine material , coarse particle recovery involves the entire flowsheet ,” Rinne said . “ For instance , there are big changes in the grinding stages needed to do this and new screening and classifying steps may need to be introduced . This is before considering the auxiliaries that are integral to effective operation of the big processing equipment .”
Metso , however , is in the final stages of developing what it says is a unique technology for coarse particle flotation that could alleviate many of these challenges .
The solution can be applied in the grinding circuit and after conventional flotation , and will not require classification or product dewatering , according to Rinne .
“ We believe that the best solution for coarse particle flotation ( or an optimised flowsheet ) will be the one that requires less auxiliaries around the main equipment , and that is what we are aiming to bring to the market soon ,” he said . Outside of the physical products in this flowsheet of the future , Metso sees increasing circuit complexity having the potential to increase the value of advanced process control systems and metallurgical digital twins such as the Metso Geminex™ to , it says , ensure the circuits are operating in an optimal state .
Gebr . Pfeiffer tackling the megatrends
As the industry continues to look for options to address concerns over its use of energy and water resources , solution providers traditionally serving different industries have come forward with strong business propositions for the mining fraternity .
Technology providers in the cement sector are part of this move , claiming their grinding solutions and experience dealing with fiercely competitive players looking to leverage every operational efficiency serves them well to make inroads in mining . This is further aided by having platforms based on dry processing routes .
One company that understands all of this – and more – is Gebr . Pfeiffer .
Gebr . Pfeiffer specialises in mill technologies , with its flexible MVR vertical roller mill for dry grinding providing , it says , a substantial benefit in energy saving , granting better liberation with higher recoveries , delivering a uniform size reduction with a narrow particle size distribution ( PSD ) and having a high reduction size ratio of up to 1,000 .
There are others in the vertical roller mill technology market competing for mining market share , however Gebr . Pfeiffer ’ s CEO , Mathias Dülfer , says his company ’ s solutions have several unique advantages .
“ First off , our MVR has a parallel grinding gap that does not exist on other solutions ,” he told IM in early-March . “ The grinding elements , in combination with the MVR suspension system , ensures that this gap – between the grinding table and the roller – stays in parallel throughout the process .”
Such a design leads to very low vibration levels , smooth operation and less fatigue on machine parts – all of which contributes to lower downtime and reduced maintenance .
“ We also have active mechanical redundancy in place with our MVRs ,” Dülfer added , explaining that the MVR has options for both six and four rollers to allow machine operation to continue with at least two rollers while other units undergo maintenance .
“ The third differentiator is the MVR offers the highest power density in the industry ,” Dülfer said . “ The compact nature of the machine , with everything included in an integrated design ( including a classifier ), is complemented by up to 18 MW of operating power , providing production rates of up to 7,000 t / h with a single mill .”
With the multi drive concept this power is delivered by up to six identical drive modules , which Dülfer says also aids operational flexibility : “ Even if one drive is under maintenance , you can continue to operate with the others . This means there is both mechanical and electrical redundancy built into our machines .”
All the above stands out from a vertical roller mill perspective , but it is also worth providing some context into how the technology differs from the SAG and AG mill platforms it could replace .
“ The consumption of energy is a big one ,” Dülfer said . “ You are typically using 30-50 % less
Gebr . Pfeiffer ’ s MVR vertical roller mill technology offers the highest power density in the industry , according to Mathias Dülfer
42 International Mining | APRIL 2024