As ore compositions at mines around the world become more complex and the grades of available resources continue to decline, the amount of tailings per tonne of metal produced is rising. Tailings management is a complex issue that encompasses the technology used to dewater the tailings, materials handling, and water management, as well as the design and risk management of the tailings storage facility (TSF). Mining companies are making significant investments to improve the efficiency and safety of their tailings management processes, driven by issues such as increasing water scarcity, environmental pressures and legislation, and the need to maintain profitability. New technologies and design strategies are needed to address these challenges.
Outotec states: “We have combined our expertise in the development of leading tailings and water treatment technologies to develop three new pre-engineered plant products, each one with Outotec’s proven and technologically advanced equipment at its heart. Bringing together our services and solutions in this way helps to make the whole process from concept development to implementation as quick and efficient as possible.”
The Outotec Thickened Tailings Plant is designed for the management and storage of tailings from concentrators. Tailings thickening helps to reduce environmental risks and results in less seepage from the TSF. “Utilising Outotec’s advanced control systems and thickener optimisation technology, the Outotec Thickened Tailings Plant offers stable process performance and consistent underflow density to ensure safe and cost-efficient TSF operation. It also enables the efficient recovery of process water, saves energy by reducing the need for slurry and water pumping, and simplifies mine closure for many applications.”
In addition to thickeners, the delivery scope for the Outotec Thickened Tailings Plant includes the feed system, overflow and underflow pumping and piping systems, gland water system, flocculant feed system, as well as instrumentation and control systems. “We also offer specialist commissioning, start-up, and training services. What sets Outotec’s solution apart is that it is combined with our proven advanced process control solution to maintain optimal performance even when there are variations in feed properties or other external factors impacting the process.”
Dry tailings disposal is a viable alternative for tailings management offering significant benefits in terms of environmental sustainability, process water recovery, and TSF footprint. The Outotec Dry Tailings Plant solution is a fully integrated design that comprises thickening, filtration, and dry material handling for the dry stacking of tailings, including all necessary ancillary equipment and systems. This solution is particularly suited to areas where water consumption is a sensitive issue, or where there are strict requirements in terms of the safe operation, management, and eventual closure and rehabilitation of the TSF. Dry stack facilities are also resistant to high levels of seismic activity.
Dry tailings storage is generally considered the safest and most environmentally sustainable technology for tailings management, and Outotec can provide a complete pre-engineered solution including plant and equipment delivery. “Our service offering includes tailings management audits, studies, as well as maintenance and remote support services.”
Mining operations are increasingly seeking ways to achieve closed water loops in order to reduce their consumption of fresh water and minimise effluent. The Outotec Process Water Recycling Plant is a fully automated standalone unit that enables recycling of process water by treating the water in a cost-efficient manner. The plant is specifically designed for concentrator plants, which dewater tailings and recycle the water back to the process. It enables undisturbed process performance by treating recycled water and removing accumulated substances to achieve the desired level of quality for the various duty points of the concentration process.
“Because the plant is a modular solution, based on predesigned water treatment units, it is fully configurable for each individual process. The modular design also means that the whole process from design to implementation can be completed as quickly and smoothly as possible. Outotec also offers a full range of complementary services including process assessment, laboratory and pilot scale testing and analysis, technical studies, and remote monitoring and support.”
Finally, the company states: “We believe that a holistic approach to tailings management offers the best way forward. In addition to equipment and complete pre-engineered plant products, we can also provide testing for thickening, filtration, materials handling and water treatment processes. We also have the capability to perform comprehensive trade-off studies in order to determine the most appropriate holistic solution for each individual project. By balancing investment against risk reduction and resource efficiency, we are able to deliver a solution that is both technically and economically feasible, and based on the most appropriate technologies.”