The disposal of tailings and associated water use is commonly identified as the single most important source of environmental impact for many mining operations. Governments, environmental groups and mining companies have been looking to implement improved methods of tailings management. Methods for tailings management depend on tailings size distribution profiles, geochemistry, local rainfall, seismic activity, local geology and topography, the availability and structure of mine voids, and many other factors. Value may also be extracted from legacy tailings dams through reprocessing and provides opportunity for economic dam rehabilitation. We see the future mine as one where water use and tailings risks are minimised through effective implementation of emerging technologies.
Maximised water recovery through tailored tailings management strategies
Sedgman has strong experience in the application of a range of tailings dewatering and deposition technologies across multiple commodities. We can support development from test work through to delivery on an engineer, procure, construct basis as well as operational management.
Whilst various dam construction and tailings deposition methods, such as co-disposal and paste backfill, are common, dewatering of tailings in lieu of constructing or raising dams is also regularly employed. The dewatering process avoids the risks associated with these dams, maximises process water recovery, and supports progressive rehabilitation. Water entrainment in tailings can be minimised through:
- Early waste rejection (coarser waste and tailings entrain less water)
- Thickened or dewatered tailings streams.
The International Council of Mining and Metals (ICMM) encourages all mining companies to improve their management of tailings facilities by adopting the Global Industry Standard on Tailings Management and leveraging technological innovation to support continual improvement. Current and emerging technologies to address mine water and tailings include:
- Tailings co-disposal
- High density thickened tailings
- In-pit backfill
- Dry stack tailings
- Optimised dewatering technologies
- Accelerated mechanical dewatering
- Acid mining drainage (AMD) treatment
- Mine waste and tailings retreatment.
- Desalination (in lieu of fresh water supply use)
- Full mine site water balance monitoring
- Circular economy solutions for tailings (e.g. ore sand, building material, topsoil)
- Recovery of metals from AMD
One of Sedgman’s key services is tailings dewatering to maximise water recovery, which is particularly critical in high water stress areas. Having extensive technical experience in tailings processing systems from coal through to base metals, Sedgman has delivered a significant number of studies and projects which include a variety of tailings dewatering technologies and reject transport and emplacement methods.
Our experience includes delivering an engineer, procure and construct contract of a new tailings dewatering facility at the Byerwen mine in Queensland. Sedgman has also delivered the Nevada Copper Pumpkin Hollow Project in Nevada, United States of America, which included plate and frame filters to dewater tailings.
We are engaged with a range of equipment vendors in the commercial application of new technologies and are actively ensuring we can provide clients access to emerging technologies as well as proven technologies in our designs, including:
- Tailings dewatering, including via belt press, plate and frame, disc filters, and both solid and screen bowl centrifuges
- Tailings emplacement and co-disposal strategies to maximise process water recovery.
The circular economy – mine waste reprocessing and repurposing
What if mine tailings weren’t considered a waste, but a resource?
Reprocessing of legacy tailings deposits can extend the commercial mine life as well as support economic remediation of legacy dams. Our experienced team can support your project through test work and evaluation to reconfiguration of existing processing infrastructure, or design and construction of fit-for-purpose reprocessing facilities.
Some historic tailings dams, and even waste rock dumps, have attractive concentrations of cobalt, rare earth elements and other critical minerals. Test work sampling programs to evaluate the value contained in historic tailings can be developed to suit any tailings dam, whether dry or under wet cover.
We have undertaken reprocessing projects in lead/zinc, manganese and coal (including scavenger circuit addition to existing facilities). With our multi-commodity processing design expertise, as well as extensive operations experience, we are well positioned to provide the right solution for your site. Working with our partners, we can provide a holistic solution from dredging and hydromining through to reprocessing and rehabilitation.
There are also both established and emerging options for repurposing of tailings. We can work with our strategic partners to provide holistic solutions for repurposing tailings, including soil amelioration.
For more insights into reprocessing and related technologies, listen to this panel discussion on minerals processing and tailings management from the 2021 Mines and METS conference, with industry experts including representatives from Sedgman, Glencore Copper, New Century Resources and Chesapeake Gold.