Letters (November 02, 1990)

Duport

Your article “The Refractory Riddle” was excellent, but contained some omissions:

You did not mention that the Duport autoclave and cyanide leach plant would be located on the mainland, outside the watershed of Shoal Lake.

I also thought you could have mentioned the Salsigne Mine in France, which produces 10% of the western world’s arsenic requirement, from a refractory gold ore. I assume that space limitations always cut out some of the interesting information.

G.R. Cunningham-Dunlop

Consolidated Professor Mines

Toronto, Ont.

Units Not Clear

Shouldn’t someone clean up the units quoted in the article “The Refractory Riddle”? A cubic metre is 1,000 litres; therefore, one milligram per litre equals one gram per cubic metre. Or should the milligrams and micrograms have been the other way around?

In any case, one part per million is a simple ratio of either mass or volume, and it cannnot equal a mass-to-volume ratio except for substances of equal density. If the litre is liquid and the cubic metre is gas, this should have been stated.

Potentially serious errors like this have long been recognized as an inherent danger in decimalization and may also be side-effects of the impractical SI version of the metric system, itself otherwise excelent. SI also extends the regrettable but apparently established habit of expressing quantities in astronomical numbers of impracticably small units. On the latter theme, the article showed a “425,000-lb. autoclave.” If it had said “210 tons,” we could have known how big it was without having to do a calculation first.

Hugh K. Taylor, P.Eng

Vancouver, B.C.

Erratum

On page 21 of your August issue, in the story entitled “The Refractory Riddle,” Isabella Wai states that the autoclave circuit at American Barrick’s Mercur mine was designed and managed by Kilborn. This is in total error as it was Wright Engineers who completed the studies, process and detailed design and the construction management for the project.

J.W. Gulyas, P.Eng.

Vice-president, Engineering

Fluor Daniel Wright

(Wright Engineers)

Vancouver, B.C.

Editor’s Note: The error in decimalization was the editor’s and not the writer’s. Please address all letters to: The Editor, The Northern Miner Magazine, 7 Labatt Ave., M5A 3P2.