TAILINGS
significant water loss at the majority of mining operations .
In contrast , HDS liberates the water entrained in the tailings and allows it to be recycled . This reduces demand for fresh water ( or desalination ), and therefore the overall water sustainability of the mine . In water-stressed regions , this is a significant benefit , not only for the environment , but also to the mine ’ s bottom line , as the financial cost of water is expected to increase substantially over time .
By dewatering the tailings and eliminating the surface pond , HDS improves the stability and safety of tailings storage , a key element of the GISTM . Meanwhile , in the event an HDS facility does fail , the lower interstitial water content and surface pond volume reduces the potential for flow , and thus the potential area of inundation . The dewatered tailings simply do not flow well , making the large-scale mudslides associated with previous tailings dam failures a thing of the past .
They add : “ HDS technology delivers this without the need to build a capital-intensive plant , as in other thickened and filtered tailings solutions . It is therefore able to offer similar benefits , at a fraction of the cost . The freedraining nature of HDS may also make the process suitable for tailings dewatering in tropical climates , which aren ’ t well suited to the operational complexity of filtered tailings .”
The interbedding of sands or installation of vertical sand drains within the tailings mass results in much more rapid consolidation than in traditional wet tailings impoundments , reducing the potential for large-scale subsidence over time . Tailings can also be deposited in cells , which facilitates progressive closure and reclamation over the life of the mine . Finally , because the HDS facility remains free draining after closure , the risk of re-saturation and longterm seepage of contaminated water is significantly reduced , even in areas of high precipitation , with reduced potential for groundwater contamination .
As a result , closure planning is simplified ; there should also be less need for long-term monitoring campaigns . Repurposing of the land can be realised quickly and handover should thus be possible much more quickly at the end of mining operations .
Bruton and Purrington conclude : “ Drawing on WSP expertise in mine waste , hydrogeology , advanced labs , pumping and pipes - to name just a few - the initial idea has been developed through a series of concept studies and lab trials and is now being tested in the field at Anglo American ’ s El Soldado mine in Chile . Here the technology is being tested at large scale , with further research underway on the performance of the tailings , as well as closure trials . The early results are extremely promising , with excellent dewatering , consolidation , and water recycling rates already achieved .”
They continue : “ There is more to be done before HDS becomes a common feature at mines around the world . Data collected at El Soldado is now informing a second trial at a mine in South Africa , where the potential for conversion of an existing TSF to HDS is to be studied . There is also potential for benefits beyond those mentioned here , with the team studying whether the HDS facility could be used for carbon storage at closure , and other exciting potential post-closure land uses . The development of this innovative new tailings technology marks a step forward in the mining industry ’ s commitment to improved safety and environmental sustainability .”
Diemme Filtration evolving & expanding
In January 2024 , filtration major Diemme Filtration ’ s new expanded capacity plant in Lugo was formally inaugurated . The investment primarily enables Diemme Filtration to multiply its current production capacity and cope with numerous challenging filtration projects involving large filter presses . IM caught up with Andrea Pezzi , Diemme Director of Marketing and Communication . He had this to say on the new facility : “ The total area is 24,000 m 2 , of which indoor factory space is about 12,000 m 2 . Everything is now ready to start production including the new paint shop and sandblasting department . We have also updated the production flows from our old plant , in this way we are not just having more space for construction , manufacturing and logistics , but also have improved the flow and efficiency through increased automation and organisation with new systems in place to monitor the production steps .” Pezzi said that while the new space will not necessarily be used only to build its largest GHT5000F Domino filter , it will give a
The Diemme GHT5000F filter press at Toquepala remains the largest operational filter press in the world
lot more flexibility should several orders for that unit need to be constructed around the same time to do that and also carry on with other orders such as its highly popular GHT2500 filters .
Moving on to talk about the GHT5000F , IM has already reported at length about the first unit ’ s installation at Southern Copper Corp ’ s Toquepala operation in Peru , and Pezzi covered some information on progress during a presentation at the SME event in Phoenix . The DOMINO has now been running for more than a year , and Diemme Filtration during that time has been able to test it under design conditions which has seen regular throughput at 80,000 t / d at the required 85 % dry or 15 % moisture content . The cycle time had been predicted to be 15.5 minutes and in most cases the actual figure has been within 15 minutes . The unit passed its Site Acceptance Test in June 2023 and is now in full operation though currently it is only being operated 50 % of the time , due to overall mine planning and scheduling reasons , and nothing to do with the capability of the plant which could run 22 or 23 hours a day if needed . The second DOMINO unit to be built is now in Chile awaiting assembly with a copper operation . Beyond that Pezzi said there has been significant interest in DOMINO from almost all of the big mining houses , some of which have had the chance to visit Toquepala to see it in action , plus other visits are planned . “ It gives them real confidence to see that a filter on this scale can operate so efficiently .”
Diemme Filtration continues to collect detailed data from the unit using its AIDA Service that uses IIoT Systems , of which the Toquepala unit is one of first global users . Its data is allowing Diemme Filtration to increase the strength of its overall database and optimise its filters globally
54 International Mining | APRIL 2024