A newly produced video by Vale Base Metals has provided details for the plan to dismantle Sudbury's Superstack this summer.
The stack became operational in 1972 and is regarded as an engineering marvel, said the video. The whole idea of the stack — built to a height of 1,250 feet — was to disperse sulphur dioxide emissions over a wider area of Northeastern Ontario, in response to growing voices of concern and dissent over the smelter pollution being produced by Inco (International Nickel Company) at the time.
Check out the video below.
In later years, Vale, the new owner of the company, launched the Clean AER (Atmospheric Emissions Reduction) Project at a cost of more than $1 billion. The project was completed in 2018.
"[The Superstack] empowered local government, the mining industry and community volunteers to launch a world-class reclamation and restoration effort in the Sudbury region," said the video. “Then in 2018 after an historic billion dollar investment in the Clean AER Project, Vale Base Metals drastically reduced emissions in Sudbury.”
The Clean AER wet-gas cleaning plant captures sulphur dioxide which is processed into sulphuric acid. Rather than one huge stack, two smaller, 450-foot tall stacks were constructed to process other gases from the smelter.
“It was an engineering and environmental success, for the Sudbury region, province and country," said the Vale video.
The Clean AER project made the Superstack obsolete. But dismantling one of the tallest manmade structures in the world is no easy task.
“A lot of preparation work has already been done, such as removing the steel liner from the inside walls of the stack,” Vale said in the video.
“The planning phase included engineering assessments, mitigation strategies and rigorous safety plans covering every aspect of the project. We've mobilized expert teams to develop and implement procedures for safely deconstructing this massive structures, setting up exclusion zones and performing continuous hazard assessments throughout the project.”
Vale said the dismantling effort will be one of the tallest structural demolitions ever attempted in North America. The stack is taller than the CN Tower's observation deck, which is at 1,168 feet, said the video.
Vale produced a previous video that outlined the similar process of tearing down the Copper Stack in 2024.
Fast forward to 2025 and the company is ready to begin the dismantling phase on the big stack. Two new elevators have been installed on two sides of the stack. The devices are similar to Alimak raise-climbing machines, elevator-like devices that have been used in underground raises for decades.
The Alimak track is bolted to the outside wall of the stack and the elevator compartment rides up and down on the track.
A two-tier work area is to be created at the top of the stack — a.k.a. "the summit zone" — where a specialized piece of equipment, similar to a hydraulic rock-breaker, has been designed to punch into and break the concrete shell "into manageable pieces". The concrete chunks will be dropped down inside the stack.
The concrete thickness at the top of the stack is roughly nine and a half inches. The thickness of the concrete shell at the bottom of the stack is 40 inches, said the video.
Every few days a remote-controlled loader will be used to muck out the debris from a special access door at the bottom of the stack.
Over a period of time, the stack will eventually be reduced to about 20 metres in height. At that point the elevators and machinery will be removed and the demolition will be done using large conventional excavators, said the video.
In terms of a timeline, the video said the work could take up to five years. Demotion work will be paused in the winter months when temperatures are below freezing.
Len Gillis covers health care and mining for Sudbury.com.
