Lafarge lowers carbon footprint at Alberta cement plant
By PATRICK CALLANConcrete Construction LEED
Recent upgrades to Lafarge Canada Inc.’s cement plant in Exshaw, Alta. have allowed the company to meet its targets of reducing sulphur dioxide (SO2) by 60 per cent, nitrous oxide (NOx) by 40 per cent, and overall dust levels from its existing cement kiln line. The plant also boasts zero water discharge from its operations.
Lafarge invested $20 million to retrofit the existing kiln line and installed noise abatement equipment. These upgrades are part of the plant’s larger expansion, which includes building a new kiln line and vertical cement mill by mid-2015, to increase manufacturing capacity by 60 per cent.
Bob Cooper, vice-president, Western Canada Cement Lafarge, described changes the company put in place to meet its environmental goals. “For particulate matter, we had an old gravel bed filter stack that came out of our kiln cooler and we basically took that stack away and vented the gravel bed filters through our main kiln baghouse.”
In order to reduce fugitive dust Lafarge paved many of the plant roads, planted trees, shrubs, indigenous grasses, purchased a new water truck to maintain the quarry hall roads, and bought a new sweeper to help with the main roads as well as the roads around the Bow Valley community in southwestern Alberta.
To reduce SO2 levels, Lafarge installed fluidized gas desulfurization, which Cooper refers to as “a wet lime slurry injection in our gas conditioning tower. Through that we have an online continuous emission monitoring system and we can monitor our SO2 levels,” he says. “For NOx, we installed selective non-catalytic reduction (SNCR)…basically it’s putting ammonia or injecting ammonia in our preheater tower and that reduces our nitrous oxides. And once again we have a continuous emission monitor and we can see that live, in real time.”
Lafarge achieved zero water discharge in the plant’s operations by installing a closed-loop water system with a chiller, which allows processed water to be recirculated within the plant. The plant no longer has to discharge its wastewater into the Bow Valley River, and having the closed loop reduces how much water it uses.
As for reducing noise emitted by the plant, it doesn’t sound like an environmental initiative, but it is, says Cooper. “We spent quite a significant amount of money on different noise abatement work, including stacks and fan silencers, and putting in quieter drive motor.”
Lafarge recently celebrated a significant safety milestone during the plant expansion project—reaching 500,000 work hours without a lost-time injury. “Everybody’s proud of that on our end of it,” says Cooper.
The next major milestone will come in the summer of 2015 when a new kiln and vertical cement mill will be completed. Both will use the most efficient cement manufacturing processes, including high-efficiency burners, SNCR to control NOx emissions, lime slurry injections, and state-of-the-art baghouses to manage particulate matter.
All of the environmental initiatives undertaken at Lafarge’s Exshaw plant are in line with the company’s overarching global sustainability goals, which include achieving 50 per cent reductions in dust emissions, 25 per cent reductions in NOx emissions, and 30 per cent reduction in SO2 emissions, compared to 2010 levels.
Cooper adds Lafarge’s sustainability initiatives at its Exshaw plant also demonstrate the company’s commitment to ramping up production and growth in Western Canada—especially in Alberta’s Exshaw and Canmore communities.
The plant’s increased production is expected to add $800 million to Alberta’s GDP per year and provide long-term employment opportunities in the Bow Valley for years to come. “We’re in it for the long run,” says Cooper. “We believe in Western Canada and we’re here to support all that growth going forward.”