Inco Superstack

The Inco Superstack at the Inco Copper Cliff smelter.

The Inco Superstack in Sudbury, Ontario, with a height of 380 meters (1,250 ft), is the tallest chimney in Canada and the Western hemisphere, and the second tallest freestanding chimney in the world after the GRES-2 Power Station in Kazakhstan. It is also the second tallest freestanding structure of any type in Canada, ranking behind the CN Tower but ahead of First Canadian Place, it is the same height as the Empire State Building and the 27th tallest freestanding structure in the world. The Superstack sits atop the largest nickel smelting operation in the world at Inco's Copper Cliff processing facility in the city of Greater Sudbury.

It was constructed in 1972 by Inco Limited (now Vale) at an estimated cost of 25 million dollars; from the date of its completion until the GRES-2 chimney was constructed in 1987, it was the world's tallest smokestack. Between the years 1972–75 it was the tallest freestanding structure in Canada.

The structure was built to disperse sulphur gases and other byproducts of the smelting process away from the city itself. As a result, these gases can be detected in the atmosphere around Greater Sudbury in a 240 kilometers (150 mi) radius of the Inco plant. Prior to the construction of the Superstack, the waste gases contributed to severe local ecological damage. Compounded by open coke beds in the early to mid 20th century and logging for fuel, an inevitable near-total loss of native vegetation occurred. Of particular interest to geologists are the now exposed rocky outcrops, which have been dyed jet black by acid rain in a layer which penetrates up to three inches into the once pink-gray granite.

By the 1950s, Sudbury's image as a barren, rocky wasteland was established. Despite the industry, a growing working class population, and subsequent deforestation of the past century, some pockets of old growth forests have remarkably survived.

The Inco Superstack dominates the Sudbury skyline.

Construction of the Superstack was followed by an environmental reclamation project which has included rehabilitation of existing landscapes and selected water bodies such as Lake Ramsey. The ambitious regreening plan which has seen over three million new trees planted within the Greater Sudbury area. In 1992, Inco and the city was given an award by the United Nations in honour of its environmental rehabilitation programs.

While the Superstack lowered the ground-level pollution in the city, it has dispersed sulfur dioxide, and nitrogen dioxide gases over a much larger area. Though not the single source of lake acidification, it appears even the heavily industrialized Ohio Valley has contributed to the ecological problem of lakes as far north as northern Ontario. Research from data gleaned up to the late 1980s demonstrated acid rain to have affected the biology of some 7,000 lakes.

Prior to Vale's purchase of Inco, a major construction effort by Inco in the early 1990s dramatically scrubbed waste gases before pumping them up the Superstack. These upgrades were completed in 1994 and emissions from then on are much reduced. Despite the 90% reduction in the sulfur dioxide and other gases, carbon dioxide and water vapour are the most visible component and continue to contribute to Vale's image as a pollution source.

It remains to be seen how Inco's new owners, Vale, will continue, considering the Brazilian company's past practices outside of North America. If Vale considers further reductions in emissions with 21st century technologies, the Superstack might no longer be needed, and could be converted into a communications observation tower.

SO₂ reductions have reached the point where the natural draught from the heat of the SO₂ is no longer sufficient. Natural gas burners and fans are now needed to move the SO₂ up the stack.

See also

• List of chimneys
• List of tallest freestanding structures in the world

External links

• Emporis listing
• Skyscraperpage
• Inco Air Quality Site
• CVRD Inco plugs sulphur dioxide holes