Inco continues research into emission reduction

Inco Ltd. says its research program is continuing to indicate potential for further reductions in sulphur dioxide emissions from the company’s Sudbury smelter complex.

In a report to the Ontario ministry of the environment, the company says research and operational tests indicate that a combination of new milling and smelting procedures for the sulphur-rich Sudbury ores offer the best hope for meeting the ministry’s limit of 265 kilotonnes of sulphur dioxide annually by 1994, decreased from the current level of 685 kilotonnes.

Under a December, 1985, Ontario regulation, Inco is required to report at 6-month intervals on reseach undertaken towards finding ways to reach the 265-kilotonne level by 1994.

By rejecting increasing amounts of pyrrhotite, a mineral which carries a large amount of sulphur, from the milling circuits, less is emitted when the material is processed through the smelter. The milling tests conducted in the last half of 1987 included the use of a prototype high-efficient magnetic separator, flotation in high-volume cells and semi-autogenous grinding. These methods of sulphur rejection have the potential to reduce emissions of sulphur dioxide by 100 kilotonnes annually.

The company reported that the largest portion of the emission reduction could come about through extension of the use of Inco’s own oxygen flash furnace smelting techniques, processing bulk copper/ nickel concentrates, additional gas cleaning facilities and a 5-km pipeline to transport cleaned, high- strength gas from the smelter to the acid plant for conversion to sulphuric acid. The existing acid plant would have to be upgraded to allow a 25% increase in production.

Inco said it spent $15 million on the sulphur abatement program in 1987, bringing the total to $120 million this decade.

The company reported it is unlikely to be able to make further emission reductions before 1990. “Subject to successful completion of technology development, the timing of implementation may, however, allow a phased reduction in emissions between then and 1994.”

In the coming months, capital costs and schedules for the project will be developed.