The building of Inco's Super Stack in 1972 is regarded as the single most important innovation in improving Sudbury's air quality.
Now the nickel processing giant is in the midst of a multimillion-dollar abatement program designed to reduce SO2 (sulphur dioxide) emissions at its Sudbury Copper Cliff Smelter Complex by 34 per cent.
George Greer, project manager of Inco's fluid bed roaster (FBR) project, a four-year, $115-million investment, says construction is about 35 per cent complete.
"The project is on schedule and on budget," says Greer, whose 16-member project staff work out of construction trailers in the shadow of the Super Stack at the Copper Cliff complex.
A few employees, like Greer, work for Inco. The rest are hand-picked independent contractors commuting north each week from southern Ontario.
Prompted by provincially mandated environmental regulations to further reduce greenhouse gases by 2006, the FBR project is being done in stages to modify one existing plant and build three others.
"We're removing 60,000 tonnes of SO2 annually up the stack," says Greer, by reducing SO2 emissions from 235 kilotonnes annually to 175 kilotonnes by late 2006.
As well, the FBR project will also recapture 80 to 100 tonnes per year of fine metal particles of nickel, copper and arsenic that go up the stack.
Using what is described as off-gas scrubbing technology, gases coming off Inco's fluid bed roaster plant are cleaned and cooled through a number of stages to produce a cleaner SO2 suitable to be made into sulphuric acid for sale on the global market.
The fluid bed roaster plant is part of the smelting process where nickel sulphide is roasted to make nickel oxide feed for refining.
The company says at that level the smelter will have cut total metal emissions by 80 per cent since it began the reduction program in 1988.
Reclaimed nickel and copper will be recycled as product, while other recovered metals will be stabilized and deposited as tailings.
Greer says the metal recycling process is voluntary with the economic returns being minuscule.
Capturing and cleaning the gas is fairly standard technology purchased on the open market, but parts of the process for capturing and separating metals for recycling is proprietary Inco technology.
Incorporating a specially-made vessel, known as the Paste Production Storage Mechanism (PPSM), it is one in a series of tanks in a patented process developed at Inco's research lab in Mississauga that removes metal solids from a water solution by blowing air and adding lime.
The overall FBR project contains upgrades to three plants.
The first plant involves modifications to an existing acid plant to handle clean SO2 coming from the new gas-scrubbing facility.
Half the job of replacing ductwork and installing heavy tank vessels was completed during the May 2003 maintenance shutdown. The rest of the job will be done during Inco's scheduled May 2005 shutdown, with more tanks and duct work installed, and the building will be expanded.
"Very intense periods," says Greer, a former Inco engineer and mine manager. "We have two to three weeks (with) 200 working on construction in that site..because we have to cram everything in two weeks.."
During the last shutdown, Inco used up all the available skilled labour in Sudbury and were forced to import some trades people from as far away as the East Coast.
Greer anticipates there will be opportunities for construction jobs next year, particularly welders, pipe fitters and iron workers
The second plant upgrade is a weak acid treatment plant to replace the current flash furnace slime system and allow for treatment of metals scrubbed by the gas-cleaning facility. It is 80 per cent complete and will house the PPSM system.
Greer says that facility is 75-per-cent finished and is scheduled for startup in July, 2004.
The third plant upgrade is a wet gas cleaning facility, to capture and clean the gas coming off fluid bed roasters. Construction will start at then end of 2004 with completion scheduled for March 2006.
A fourth new plant under construction this spring is a slaking plant.
A local consortium, including Sudbury Lime Ltd., is building the facility just outside the smelter gates to provide Inco with lime for up to 15 years in all its smelting/refining processes. It will be ready by early July.
Since the project began in 2002, much of the work has been sub-contracted to Sudbury companies with about half of the $115-million budget ending up in the pockets of local contractors and machine shops.
