Q Is the interest in paste and filtered tailings dominated by greenfield projects or is there also a significant proportion of expansion and extension of existing operations KR : A majority of the lab-based studies ( at least three to one ) we are doing are actually for already operating brownfield sites where they are looking at filtered tailings both as a way to recover water and reduce fresh water intake but also as part of their wider sustainable mining plans . And of course reduced risk and reduced consequences of any kind of TSF failure . Existing operations also move much faster through lab to PFS to basic engineering as they have an existing solution need . Greenfield studies include laying out their initial flowsheet designs that they will use to go forward with permitting , |
supply all the options , we are not biased and trying to focus on one solution – it is about what ’ s best for the project . Every site is different with different variables so we propose the best |
After the successful EcoTails™ approach of mixing filtercake with waste rock ( shown here being deposited as GeoWaste™ ) comes a new approach , EcoPaste™ , where paste will be mixed with waste rock |
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which of course can take years to get approved . FS : A lot of brownfield plants are also permitted for a certain amount of water and in order to complete an expansion they need more water – recovering more water from tailings is one potential source and a lot easier than getting permission to use more fresh water .
Q Is the FLSmidth strength a combination of a range of experience of project sizes , ability to manage large projects plus a comprehensive equipment line ? KR : Yes our experience comes up quite a bit in discussions when customers are evaluating options . We also sell pretty much all types of relevant dewatering equipment – different types of filter and belt presses , thickeners and centrifuges . So we can test all of the them compare and contrast results . And as we can
Fred Schoenbrunn
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equipment solution to meet their needs . If the solution is for paste or filtered tailings at a large tonnage mine , such as South American copper – trucks and dozers are no longer cost effective – you need to evaluate conveying of filtercake as well as stacking systems – and these mass material handling systems are also in our solution offering .
Q Where does MissionZero as an initiative fit in with your tailings solutions including the effect of new upstream technologies on downstream tailings ? KR : The MissionZero impact is not limited to dewatering – but as you say the impact of upstream innovations to the material we are dealing with . coarseAIR™ for example as a new flotation technology allows separation at coarser grind sizes and therefore coarser tailings material . If you implement our vertical OKmill™ or HPGR technologies you will get less fines – improving dewatering capability . Reducing fines also improves geotechnical properties of filtered tailings . Even things like rake design innovation and new control strategies improve the efficiency of the thickener itself and enable underflow consistency even when the nature of the feed material changes – this is crucial in paste operations where there is orebody variation and operations struggle to maintain consistent paste rheology . FS : We are doing a lot of work for optimising thickeners to be more consistent and reliable in producing thick pastes . As part of that we have
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been doing CFD modelling of the mud bed in thickeners and we have developed a new inner spiral rake blade that assists greatly in high tonnage (> 1,000 t / h ) thickening operations in improving mud bed flow patterns and mud bed residence time distribution . The first installation is showing substantially lower torques at high rheology outputs .
Q You mention comingling earlier – following the EcoTails™ project developed with Goldcorp ( which is now part of Newmont ) are you advancing any similar processes elsewhere ? KR : The EcoTails™ project looked at mixing filtercake with waste rock through conveyor transfer chutes . That approach is being looked at again as part of the mentioned pilot campaign in South America which is a large base metals mine . On top of that in the same project we are also looking at mixing paste tailings with waste rock – which we are referring to as EcoPaste™ . Again this would use chutes but may require a different chute design because you obviously have much wetter material and still need to avoid blockages . We will investigate that through both physical measurements and videos . For both the filtercake with rock and paste with rock , material from the chutes will also be sent to a geotechnical company to build test pads to test stability , similar to what was done for EcoTails™ . Our primary focus is the dewatering and mixing of the material after it has been produced .
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