Huge Mine Produces Clean Water Too

Any Arctic mining operation faces a number of unique challenges, not the least of which is managing water treatment to meet the stringent demands of a fragile ecosystem. In addition to the environmental concerns, the severe weather conditions add to the burden, since typically mines can only treat water during the summer months (June to September) when runoff volumes are high.

Xstrata Nickel -Raglan Mine operation in Quebec has discovered that by leveraging newer water treatment technology, it can not only meet strict discharge guidelines (in line with Nunavik strict regulations), but also extend the available window of opportunity for treatment to six months.

Since 2003, the operation has been meeting its waste water challenge with a proprietary process from BioteQ Environmental Technologies called ChemSulphide®.

Located in the far northern region of Qubec (1800 km north of Montreal),

Xstrata Nickel -Raglan Mine property has a series of high-grade ore deposits, stretched across nearly 70 km, with nickel and copper as the primary metals. The operation consists of a network of open pit and underground mines (90% of production at Raglan is from underground sources). Currently there are three active underground mines and one open pit, while a fourth underground mine is under development.

In 2008, the mines produced 26,000 tonnes of nickel, 6,400 tonnes of copper and 500 tonnes of cobalt.

According to Senior Engineer -Mining Projects, Martin Beausjour, effective water treatment is vital when operating in an extremely fragile environment. “Our commitment is to get water back to a natural state and in compliance with regulation, so it needs to be ‘cleaner than clean.’ Given that we are operating multiple mines, our approach has always been to integrate water management strategy with our mining strategy. In other words, before we open any mine, we reevaluate the water management strategy first.”

To achieve the highest performance levels and capacity, Xstrata Nickel – Raglan Mine commissioned the Zone 3 water treatment plant -which is owned and operated by BioteQ Enviromental Technologies Inc. -to process waste water from three of its mining operations.

“A certain amount of water is generated in each sector,” he explains. “We automatically treat any water that is collected in the open pits to a level where it can be safely returned to the environment.”

Efficiency is a key element in Xstrata Nickel -Raglan Mine’s water treatment strategy, since the open pits must be emptied every year in order to recollect the runoff the following year. To optimize water treatment capacity, Xstrata Nickel -Raglan Mine installed a pipeline system to transfer the waste water from each of the three sectors to a central dyke reservoir for treatment by the ChemSulphide® system. The farthest sector is 7.5 km from the plant. At this point the plant treats between 750,000 and 1 million cubic meters of water a year. BioteQ provided all capital and commissioning costs of the plant, and charges Xstrata Nickel -Raglan Mine a treatment fee per cubic metre of water treated.

ChemSulphide® uses a chemical sulphide reagent to treat water. This reagent is introduced to a contactor tank that contains the water to be treated, and the solution chemistry in the tank adjusted to selectively precipitate metals as pure metal sulphides. The precipitated metals and treated water are pumped to a clarifier tank where the clean water is separated from the metal solids and either discharged to the local environment or recycled. The metal solids are filtered to remove excess water, producing a metal product suitable for concentration.

The outputs of the process are a metal concentrate and clean water that can be discharged to the environment. Metals that can be recovered include nickel, copper, cobalt and zinc. In the case of Xstrata, nickel concentrate extracted from the process is sent for milling and resale. At the same time, the process produces clean water that meets strict environmental regulations.

Using ChemSulphide® technology, Xstrata Nickel -Raglan Mine is able to treat water as a continuous process.

Beausjour says “We don’t need to process water in ‘batches’. Rather we can continuously treat it through the plant for release to the environment, so it’s faster. And unlike other treatments, there is no sludge generated. That’s a considerable advantage.”

Speed is of the essence when one takes into account the short time frame for water treatment he adds. “In the Arctic, you have ice from October to June. When runoff begins you have to be very quick in treating your waste water. With lime treatment, you have less than four months to treat a yearly volume of waste water. With our system we can treat it until November which gives us an extra two months -that’s an extremely important advantage.

” Applying BioteQ’s technology at Xstrata Nickel -Raglan Mine has delivered a number of processes, environmental and economic benefits. Not only has it eliminated the production of sludge, it has increased treatment capacity and speed, generated revenues from waste product and extended treatment time frames. Most importantly, it is able to treat water to a “cleaner than clean” state for safe discharge to the environment.

As operations continue to expand, Beausjour says that the success of its water treatment strategies have laid the groundwork for future initiatives. “As we look at options to increase our treatment capacity, what we have done so far will definitely play a part in our decision making. We see a lot of potential.”

David Kratochvil is the President and Chief Operating Officer of BioteQ Environmental Technologies, Vancouver. He holds a PhD

in Chemical Engineering, and has 15 years of experience in wastewater treatment and chemical processing.