FLOTATION TECHNOLOGY
DRC and elsewhere .
Looking ahead , Metso Outotec has several new projects looking at recovery of fine and coarse particles that cannot currently be recovered effectively
using existing technologies , and will be launching some of these products soon .
Eriez on meeting the coarse particle flotation challenge
The mining industry needs some new technology that can provide a step change in response to productivity & sustainability challenges , and one of these is coarse particle flotation . Eric Bain Wasmund , Global Managing Director Eriez Flotation Division told IM : The intensity of grinding is a direct requirement of the conventional flotation process . Stirred tank flotation cells , which are the workhorse of the industry , quickly become inefficient at floating ore as the particle size increases ( or decreases ) outside of a narrow range . Simultaneously , the finer an ore is ground , the more energy is required , a phenomenon known as Hukki ’ s conjecture . It is estimated that 36 % of all energy used in copper and gold mines is associated with comminution . Besides energy , overgrinding to accommodate the limitations of conventional flotation has other downstream consequences . The coarse particles in the size distribution are still lost in conventional flotation . The fine tailings have low hydraulic conductivity and are therefore difficult and expensive to de-water . This means most tailing facilities are wet and significant amounts of water are
Russian gold flash flotation
Russian gold mining major PJSC Polyus told IM that the implementation of flash flotation technology in the
form of Metso Outotec SkimAir flotation cells at Polyus ’ assets has had a significant positive impact on recovery rates at its existing processing facilities translating into an overall recovery increase of approximately 3-4 %). Polyus has already installed SkimAir flash-flotation flotation cells at its Krasnoyarsk business unit ( at the Olimpiada and Blagodatnoye mills ), where this technology has been tested and proven to positively impact the efficiency of those operations . Polyus ordered its first SkimAir 500 flash flotation cell in 2016 . The cell was installed in the Olimpiada ZIF-4 concentrator . This successful installation led to flash flotation roll out at the ZIF-3 , ZIF-2 and ZIF-1 concentrators . There are also two SkimAir units at Blagodatnoye Mill 4 and another four spread across its other three mills . Following that , Polyus launched the roll-out of SkimAir flash flotation technology at its Natalka mill and the company is now assessing the option of flash flotation technology introduction at new facilities , including those projects currently at different stages of engineering studies ( pre-feasibility and feasibility stages ), namely Mill 5 ( additional 6 Mt / y ) at Blagodatnoye and its huge Sukhoi Log project .
tied up in tailing outflows and cannot be directly recycled back to the operation instead being lost to evaporation .” Another consequence of low hydraulic conductivity is poor drainage , a known mechanism for liquefaction of solid and semi-solid tailings .
Eriez Flotation has developed and commercialised a flotation cell called the HydroFloat ® that is based on fluidisation rather than stirred mixing . “ For most mineral systems , HydroFloat shifts the efficiency curve for flotation by roughly a factor of two . For example , the stirred tank flotation recovery of a 150 micron liberated porphyry copper particle might be 95 %, and 10 % for that same ore at 300 microns . The HydroFloat flotation recovery of the 300 micron particle could still be close to 95 %. The HydroFloat
uses counter-current plug-flow contacting , a densephase aerated fluidised bed and a zero-order froth , all completely different principles than conventional flotation .”
Pilot plant work on mine tailings began with the HydroFloat in 2013 . The benefits were reported publicly by Rio Tinto from work done at their Kennecott Utah Copper tailing facility in 2015 where it was stated that 70 % of coarse copper contained in tailings and 90 % of coarse molybdenum contained in tailings could be recovered with the HydroFloat . This application , called the tail scavenging application , was first practised on a commercial scale by Newcrest at their Cadia Valley Plant starting in 2018 .
Wasmund states : “ In this application , The
Dry Stack Tailings ( DST ) systems are particularly suited to operations where water conservation is critical ; as well as providing significant environmental and safety benefits too .
We are able to provide a complete DST system or individual equipment pieces to suit the unique requirements of your operation .
DST forms part of our commitment to safe and sustainable global operations . TAKRAF - your complete solutions provider .
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