HEAP LEACHING & SX
Stacking up
While the leaching dynamics at every heap leach operation are integral to achieving good recoveries , the process of stacking the heap is equally important .
FLSmidth has recently updated its mobile stacking conveyor ( MSC ) line to offer solutions tailored to the ground conditions of each site but consisting of standardised and modularised components that are easy to replace and service .
Luc Tellier , Process Line Manager , IPCC at FLSmidth , expanded on these updates when speaking to IM : “ Over recent years , there have been quite a lot of improvements during the design phases for individual machines . We have decided to put them all together to provide a universal offering with an updated MSC .”
This has seen the company expand the type of crawler tracks it offers for MSC units – an offering that can go from narrower D4 chains with 42 in ( 1,067 mm ) tracks up to wider D11 chain with 72 in tracks – to support the ground-bearing pressure dynamics at play .
Aided by sophisticated modelling software , the company can more accurately understand these ground-bearing pressure considerations at each site , Tellier explained , using a wide assortment of tracks to design the most suitable solution . The company ’ s MSCs now uses square hollow section steel profiles on the base to avoid the spillage and ingress issues that come with , for example , I Beam or T Beam designs , while a new capstan winch design helps tripper conveyor movement and stability – “ if one cable were to break , this new design would keep the tripper conveyor and reclaim hopper intact and in place , preventing a runaway situation ,” Tellier said .
The tracks are suspended with four cylinders on each side to level the bridge to keep the adjoining conveyor straight relative to the track , Tellier explained .
The whole track system is made up of standardised products from the likes of Caterpillar , Berco , etc , but arranged on a customised ( bespoke ) frame by
FLSmidth , Tellier said , adding that the company is the only OEM providing a single-track MSC design .
He added : “ The powerpack has been modularised so that one powerpack per crawler unit drives the hydraulic motor and the cylinders for the levelling system of the crawler .”
Speaking of hydraulics , the company has shifted the MSC ’ s operation away from electric propulsion to hydraulic propulsion to improve cooling efficiency , Tellier said .
This is rounded out by an enclosed and modernised control system that uses the latest in GPS tracking , radar and wireless technology .
“ All of these features make it a much more modern machine compared with the first models ,” Tellier said . “ The whole design is much more componentbased and modularised so it fits together a lot easier .”
These updates – especially the modernised control system – have come at just the right time , enabling heap leach operations to leverage FLSmidth ’ s BulkExpert™ solution focused on unmanned and optimised operation of dry bulk equipment .
Tellier explained : “ We ’ ve modernised the complete automation system : we ’ ve added sensors for condition monitoring of the equipment and the structure and , furthermore , for stockpile creation . We have the capability to visualise the piles of material that have been built up and reclaimed , while adding additional features for collision avoidance to increase machine safety .”
He expanded on the rationale for such a move : “ There has been a big push from industry to have the system more autonomous and have more data generation and data-handling capabilities to show where certain material is located and when it was deposited there . This data is now stored to allow for analysis of moisture content , location , etc at any point in the process .”
Moreover , Neste Renewable Isoalkane evaporates at a sustainable technology methods , with Metso Outotec lower rate , which improves copper extraction leading the design of processes that are more efficiency and safety due to significantly reduced efficient and come with a better / lower impact to the volatile organic compounds , the company environment .” added .
Alejandra Norén , Head of Production Partners Kaarlo Haavanlammi , Director , Base Metals , Metso Management , Renewable Polymers & Chemicals ,
Outotec , told IM : “ The base metals industry is
Neste , added : “ There is more and more pressure on generally looking for more environmental friendly and volatile organic compound ( VOC ) emissions in some
Benefits of bio-based diluents in solvent extraction
countries and regions , with these emissions economically penalised . At the same time , a low CO 2 footprint is very much top of mind .”
This latter consideration is aided by applying a certified method for tracing the raw materials from their origin until the usage point of Neste Renewable Isoalkane . This enables the end user to estimate the product ’ s environmental footprint very closely .
The bio-based Neste Renewable Isoalkane diluent reduces VOC emissions and hygiene-related work hazards , Norén said .
Following the conclusion of various tests and laboratory pilots , Neste has proven the reduced evaporation credentials of the diluent , while securing less VOC emissions , Norén said . This work implies the diluent could prove effective in lower doses than the conventional fossil-based alternatives used across the industry .
Norén said : “ The solution proposed is based on the concept ‘ less is more ’, meaning with the use of less product , performance is comparable and improves the global footprint .”
In terms of market development , Norén expected greenfield sites to be more active in adopting this technology , with brownfield operations converting to bio-based diluents more progressively .
“ Nevertheless , we are actively promoting it to existing and new customers ,” Haavanlammi and Norén said .
Discussions are ongoing with possible Finnish and North / South American industrial partners for testing of the technology on an industrial scale , Haavanlammi added .
IM
NOVEMBER / DECEMBER 2020 | International Mining 61