INCO CLEANS UP

Provided that the first flash furnace, as well as a new acid plant and additional oxygen plant are completed as planned by late 1991, Inco expects to see a significant drop in SO2 emissions earlier than 1994 — a reduction of about 100,000 tonnes per year, explains Executive Vice-president Roy Aitken. “The remaining 320,000- tonne-per-year reduction would be achieved in 1994, after the remainder of the components are in place and all process modifications have been completed.”

He added: “Not only will we achieve a massive reduction in SO2 emissions, but our program will provide other environmental benefits as well. For one thing, the use of pure oxygen rather than natural gas will mean that we will no longer emit to the atmosphere gases which contribute to the greenhouse effect as a result of the burning of fossil fuels. There also will be benefits in the workplace, since the use of enclosed flash furnaces, rather than more open reverberatory vessels, will result in a cleaner, safer work environment.” SO2 Abatement at a Glance

* The Ore — Sudbury ore contains eight parts sulphur for every one part nickel. The task is to extract nickel and copper from the ore, yet capture 90% of the sulphur before it reaches the atmosphere as SO2.

* Milling — The ore is crushed and a magnetic fraction of the high sulphur- bearing pyrrhotite (iron sulphide) mineral is rejected.

* Smelting — The remaining bulk concentrate is smelted in high-efficiency oxygen flash furnaces and the SO2 generated is fixed as liquid SO2 or sulphuric acid.

* Product — Matte (the balance of materials left after the smelting process) is further refined into nickel and copper.

The entire abatement program will cost an estimated $494 million (Canadian) over the next five years, according to the company. Of this total, $69 million will be invested to modify and rationalize milling and concentrating operations, permitting the separation and rejection of additional quantities of pyrrhotite. The remaining $425 million will be invested in new oxygen flash smelting furnaces, a new acid plant, a new oxygen plant extension and other services, the company reports.

As Aitken explained in a speech last year to the World Resources Institute in Washington, D.C., Inco has a record of pursuing sound environmental practices.

“By the time the world came to understand that the environment could be exhausted and destroyed, Inco had already begun to turn the corner. During the 1950s, we developed our oxygen flash furnace’ smelting technology, which greatly improved our capacity to capture sulphur dioxide. We also developed a means of magnetically separating pyrrhotite, which was rejected before it reached the smelter.

Sulphuric acid operations were greatly expanded in the 1960s, even though the fertilizer business, its main outlet, was not at all economic, and we began an extensive program of reforestation and of planting grass and grain on eroded mine tailings.

“Our tall stack was constructed during this period to replace three smaller existing Sudbury stacks so as to ensure minimum, harmless ground-level concentrations of sulphur dioxide. It turned Sudbury into one of the clean air’ communities of Ontario. Though it was the latest technology at the time and was a decided step forward in our comprehensive program to reduce the environmetal impact of Inco’s operations, the superstack also became a target of environmental activists and a symbol of growing concern about airborne transporation of pollutants and acid rain. The symbolism has obscured the fact that Inco’s total emission have been reduced by some 70% since the high point in the mid-1960s.”

]]>