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Long Harbour: even more ways to reduce freshwater use

October 20, 2021

Long Harbour’s port stormwater pond will soon replace the freshwater currently used in the plant’s crushing and grinding circuits. Photo: Vale Archive

If all goes well, and Ashley Viscount, a Long Harbour global trainee at our Newfoundland and Labrador Operations, believes it should, by early next year our Long Harbour Processing Plant will have reduced its annual freshwater use by up to 96,000 cubic metres – enough water to fill 38 Olympic-sized swimming pools! 

The plan is to replace the use of freshwater in the Crushing and Grinding circuits with mostly rainwater and runoff collected in stormwater ponds. 

We’re taking rain and natural runoff water and making use of it.

“It’s in the planning stages,” Ashley said, “and we still need to evaluate how it’s going to physically tie into our system.” 

Figuring out the process

As part of their evaluation process, Ashley and her colleagues analyzed samples from Long Harbour’s stormwater ponds over a three-month period. Photo: Vale Archive

What is reassuring, however, is that from a process perspective, the switch to rainwater should pose no problems to the existing methods. Over the course of three months, Ashley and her colleagues carried out a number of analyses on samples from the stormwater ponds. The water there is exposed to high levels of nickel, vehicle traffic and silica dust and, as a result, needs to be sent to the Residue Storage Area, where it can then be sent to the Effluent Treatment Plant with other wastewater so that it can be safely discharged into the ocean. 

“Before we could even consider if it was feasible, we had to look at it from a process perspective,” she explained. Would the additional chlorides affect the rubber lining of the tanks and pipes? Would it affect the final output?” It’s a delicate balance as high levels of various ions could affect the process downstream while other organic components could erode rubber linings in equipment. “We wanted to be sure that we weren’t going to be creating additional risk,” Ashley added. 

Saving freshwater  

The results to date are promising. The wastewater has demonstrated fairly similar levels of organic components as the process water being used now. “Everything looks good,” Ashley said, meaning that the stormwater can instead be pumped directly into a water tank for the Crushing and Grinding circuits. “We won’t have to treat it. It can go straight into the circuit.” She estimates that the use of stormwater is expected to save around 8,000 cubic metres of freshwater a month.  

With everything looking good from a process perspective, all that remains is to figure out how it will tie into the existing system. Ashley doesn’t expect it to be difficult. “It’s fairly easy,” she explained. “We literally just have to run another line to the tank off another line that’s already there, and install some new pumps, but we need to go through the process to make sure the components are compatible.” 

‘It’s a really great development’ 

As our company works towards our goal to reduce 10 per cent of our freshwater use by 2030, initiatives like these are critical. “It’s a really great development,” Ashley said. “At the end of the day, we’re taking rain and natural runoff water and making use of it while saving on how much wastewater we’re treating and how much freshwater we’re using.” 

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