The Lafarge cement plant in Exshaw has been serving Alberta’s construction industry since it began operations in 1906. In fact, the plant is the reason Exshaw exists. The hamlet was born when 300 men, some with families, came to build the facility. More than 100 years later, the Lafarge plant is now bigger and more environmentally friendly than ever as its expansion and upgrade wrap up.
The project, which began in 2013, includes building various cement production line components, a 110-metre-diameter stacker/reclaimer dome, a 133-metre-tall preheater tower, a new vertical raw mill, an energy-efficient vertical cement mill, a state-of-the-art baghouse, a clinker cooler system, a new kiln and a 39-metre-tall, 16.6-metre-diameter blending silo (a technically complex and challenging part of the expansion that won an Alberta Construction Magazine Top Projects Award in 2014). Environmental upgrades were also made on an existing kiln, and a new zero-discharge water-cooling system was installed.
Along with increasing productivity, improving the plant’s environmental performance was a major goal of the project.
“Technologies evolve over time and with new technologies, it takes less energy to produce a certain amount of throughput, which is good for everybody,” says Phil Allen, senior project manager, Lafarge Engineering Centre, LafargeHolcim. “So we made upgrades to Kiln 5—specifically the environmental controls— shut down the older, less-efficient Kiln 4 and built a new Kiln 6.”
Kilns 5 and 6 are equipped with flue gas desulphurization to control sulphur dioxide emissions and selective non-catalytic reduction to control emissions of nitrogen oxide and nitrogen dioxide. Consequently, even though the expansion gives the plant a 60 per cent increase in capacity, it will also result in a reported 60 per cent decrease in sulphur emissions and a 40 per cent decrease in nitrogen emissions.
The kilns are set up to use natural gas because of the low cost of that fuel right now. But they can be adapted to burn low-carbon fuels as well, which may be better for the environment.
The expansion and upgrade have also reduced emissions of particulate matter, and the facility no longer discharges cooling water but rather recycles it instead. Fan and stack silencers were added to reduce noise as well.
Blowing in the wind
There’s nothing particularly unique about building a cement plant—it’s a construction job like any other, requiring the same trades and processes. What is unique about this project is its location. Lafarge’s operation is located in the Rocky Mountains, 15 kilometres east of Canmore, Alta., within the Bow River Valley.
“The topography is not very conducive to civil construction,” Allen says. “We had a very steep rock face that we’re working to build from and the equipment loads are quite high, so some structures are built directly on bedrock while others are on caissons.”
When Allen speaks of caissons, he’s referring to large underground steel-reinforced concrete support columns formed by drilling holes up to 100 feet deep into the earth. They provide a way of tying a structure sitting at surface level to an underground foundation system. Because two types of foundation systems had to be used, the individual foundations for the equipment of the new part of the plant had to be designed in such a way that structures near each other were designed with either one type of support or the other to avoid potential cracking.
But by far the biggest challenge was the wind. “The plant is almost in a bowl in the surrounding mountains, like a wind tunnel. Though we did anticipate significant winds, we didn’t anticipate it to be as bad as it was,” Allen explains.
Just how windy was it? Wind gusts exceeded 125 kilometres per hour at times, and during peak construction in January 2015, the 715-tonne crane on site was only able to operate on three days. Obviously, the schedule was impacted. (Completion of the project was initially scheduled for 2015.)
The wind affected decisions made during design and construction. For instance, the 35-metre-tall raw materials dome is made of aluminum because aluminum domes can be constructed from the ground up, significantly reducing the amount of time people are required to work at heights. While under construction, the dome had to be anchored with cables to 42 concrete pads put in for that specific purpose—again due to the wind.
In spite of the wind and the need to work at heights, 2.5-million personhours have been worked without a single lost-time incident. Allen attributes the successful safety record to an intense focus on behavioural safety that extends from the management team to everyone on the site.
“The guys in the field are actively partaking in safety observation report cards, so rather than having the safety personnel out there making sure things are safe, we’ve got everyone out there making sure things are safe,” he says. “We see a direct correlation in terms of when observations are down, incidents are up, and vice versa.”
No place like dome
As the project went on, the project team saw an opportunity to put the raw materials in a dome, which would bring them indoors so they were no longer affected by wind and weather. It also made the process more efficient because the reclaimer/stacker system could be located inside the dome.
Plant manager Jim Bachmann explains the benefit: “The stacker rotates 360 degrees, and as it is rotating, the material is dumping from the top of the dome down to the base. When the material drops, it’s being blended as it’s being placed into a pile inside the dome. On the other side of the stacker, the reclaimer pulls the material off in a different way from which it is being stacked. So you’re getting a blending motion while it’s being stacked and a different blending motion as it’s being reclaimed. The combination of being stacked and reclaimed inside a dome really helps the consistency of our product.”
There were seven massive cranes on the site, but it’s the dome that has drawn much of the attention of the surrounding community. At the employees’ request, Lafarge took the opportunity to engage with the public, running a “Name the Dome” contest. Out of more than 300 entries, employees chose the name EcoDome.
“It was kind of appropriate, given that the primary purpose of the dome was to improve our impact on the ecosystem here,” Bachmann says. “We also like to view ourselves as an economic driver for the provinces, so EcoDome made sense in a couple of different contexts.”
Ready to serve
As of the end of April, the project was almost complete and ready for commissioning. It gives Lafarge the capacity to produce over 2.2 million tonnes of cement per year—up from 1.3 million tonnes—and has been estimated to have a $1.2-billion annual economic impact on Alberta.
“Having a plant near the markets of western Canada is much better than importing cement from foreign countries,” Bachmann says. “We’re in the right location to be able to feed the oil and gas sector when it recovers. This plant has shaped western Canada for almost 110 years and will be here when booming days return.”