WATER MANAGEMENT
water usage. This saving is predominantly due to projects such as more effective dust suppression, dewatering of tailings and more efficient ore separation – all of which contributed to the approximate water saving of 25 million m 3.
“ As well as saving water, we improve efficiency by increasing how much water is recycled and reused at our sites. For example, production at Los Bronces copper mine in Chile was constrained by water supply challenges in 2015, which provided an extra impetus to reduce our fresh water consumption. To overcome this particular challenge, we implemented a number of measures, including running the recycling system at maximum capacity. We continued to transport water via a 56 km pipeline from the Las Tortolas tailings dam in Chile to Los Bronces, using a special water-recycling system. Los Bronces currently recycles more than 78 % of available water. Overall, this has helped us meet 64 % of our total operational water requirements with recycled or re-used water – a key milestone as we move towards our longterm goal of 80 %.
“ Investing in new integrated water solutions is one of our most important technology focus areas and is fundamental to achieving a stepchange in water-efficient mining. Over the last six years this investment has enabled us to introduce several cutting-edge technologies. These innovations include separating water streams that do not contact waste water; discharging less water to tailings; remote monitoring of water flows and levels in dams and tailings, as well as piloting passive water treatment technologies. We are proud of the fact that many best-practice technologies that improve water efficiency are now standard procedures at the majority of our operations.
“ In June 2015 we were thrilled to hold our first FutureSmart™ Technology Open Forum in London, gathering world class experts from a variety of industries to help solve some of our big challenges. The ultimate goal of the Open Forum was to find more efficient ways to mine but also, crucially, to reduce our impact and create a positive legacy for the surrounding environment and local communities.
“ Our first forum had representation from more than 75 different market sectors, 30 companies, 16 countries and six continents. The outcome was more than 1,150 hours of discussion and 1,000 generated ideas.
“ Potential solutions identified at the Open Forum include reducing the quantity of tailings that we produce through an increased focus on rejecting water earlier in the process. In some other cases, where there is too much water rather than too little, the forum developed ideas on high volume, low-cost water treatment to return the water safe for human use.
“ Growing regulatory and social pressure, increasing demands for limited natural resources, climate change and the changing costs of water all highlight the business imperative of achieving water resilience. Our immediate focus is on securing adequate supplies and using resources more efficiently so that we can ultimately reduce our reliance on‘ new’ water to near-zero.”
Impact without major capital expense
Nalco Water considers that“ today’ s challenging economic environment requires more creative solutions that can reduce freshwater usage and minimise discharge without major capital expenditure, whenever possible.
“ The first step in any water management plan is to ensure production is optimised with process water programs that maximise yield and recovery in mining operations. Keeping more of the valuable product that you want to recover out of any effluent stream simply makes good business sense and minimises environmental impact. Nalco Water has helped the mining industry maximise profits and minimise problems with effective process chemical programs and dependable service for decades.”
It is now offering the Environmental Analysis and Chemical Treatment,( EN / ACT ®) program, a total systems approach to aid in water clarification and conservation that helps customers comply with environmental regulations. As mine water applications tend to be highly variable in terms of flows and / or, contaminants EN / ACT programs include practical application equipment design and ongoing field and analytical service, to make program management easy and economical. Each EN / ACT program is designed to fit the individual equipment, operating conditions and specific goals of the operation, and can include: n Run-off / discharge water treatment programs
Water recovery pumping station at Anglo American’ s Las Tortolas tailings storage facility
including heavy metals removal, emulsion breakers, and“ fish-friendly” water clarifiers n WaterShed™ tailings management programs with additives that bind the solids within tailings slurries to create a free draining structure and provide immediate water release for recovery and reuse. Poor water quality and clarity can have a significant negative environmental impact, not to mention incurring costly compliance citations and negative attention in the community. A customised EN / ACT program can settle solids to help control clarity, remove heavy metals and correct acidic mine run-off problems that can occur when processing minerals,( re) handling tailings refuse or treating water from run-off or underground mine works. Components of the program include: n A complete line of clarification aids effective over a broad range of conditions n“ Green” coagulants for sensitive applications where discharge is bound for fish-bearing streams n Passive flocculants designed to be used year round whenever water volumes and flows dictate discharge n Metals removal technologies to address soluble metals such as aluminium and selenium n Emulsion breakers to ready water from underground workings for discharge to open surface streams n Feeding equipment well-suited to hard-to access locations. Increasingly aggressive and less selective mining methods have come into wider use to improve mine productivity. However, the same methods can generate an exceptionally high
36 International Mining | MARCH 2017