At the onset it became evident to the pioneer companies that the ores of the Sudbury district should not be direct smelted. The grade of mate produced was usually quite low resulting in too heavy a strain on the converters. Also with the sulphur content so high, it was imperative that it be driven off. Hence recast yards were required.
The summer of 1888 saw the Canadian Copper Company firing its first roast heap. This was but five years since the ores had first been exposed near what became known as Murray Mine. Then mechanization was not the norm with the ore brought to the Copper Cliff beds by wheelbarrows.
By 1912, there were three roast yards within a mile of Copper Cliff. With as many so close to the town, it was virtually impossible for the vegetation and the inhabitants to escape the sulphur atmosphere. However, 1915 saw plans under way for the establishment of beds in an area distant from the community.
For a roast bed, a fairly level area of ground with suitable drainage is required. Also, the bed should not be near a heavily populated area nor should it be located in an area of agricultural importance. In February 1916 the O’Donnell yard, meeting the requirements, was opened by the Canadian Copper Company.
In Graham Township
The O’Donnell yard, named for employee John E. O’Donnell, was established in Graham township on the Algoma Eastern Railway about four miles West of Creighton mine. Soon a village would be established.
With the new yard, the era of the wheelbarrows at the roast bed was over. The new yard had a bridge crane with a span of 170 feet. From a receiving hopper, the ore was taken by conveyer to the highest point of the bridge. From there it was discharged on a 30-inch shuttle conveyer belt. With mechanization, the beds were built uniformly.
In building a roast pile, the first operation consisted of laying a foundation of wood, usually dead pine to a depth of 12 to 18 inches. These were usually built at intervals of about 10 feet. Then the coarse ore, about two-thirds of the whole, was piled on the wood followed by a layer of medium sized ore. The heaps were capped with finer ore that served to regulate the speed of combustion.
At O’Donnell, about 250,000 tons of ore would burn in 100 heaps. After the lighting, the wood burned out about 60 hours. The pile would continue to burn for approximately three to four months.
During the roasting, the outer shell of the piles became reddish in color as a result of the oxidation of iron. On the surface, sulphur frequently sublimed during the initial stages. Later, the sulphur would be driven off.
When the roasting was complete, the ore was dug out by steam shovels and loaded into 50-ton cars. The ore, reduced from about 23 per cent sulphur to about 10 per cent, then was transported in the cars to the bins behind the blast furnaces.
Most in Roast Beds
At the time the O’Donnell yard was established, it appears the Canadian Copper Company roasted approximately 60 per cent of its ore at roast beds. Then, the Mond Nickel Company had a roast yard three quarters of a mile south east of the Coniston smelter. The yard had a capacity of 40 heaps with the yard at one time containing between 60,000 to 100,000 tons of ore. For the Mond Nickel Company approximately 30 per cent of its ore was roasted on the beds.
Roast beds, though an established practice identified with the early mining scene, had its share of critics. Since there is no protection from the weather during roasting, a portion of the valuable metals was leached out by the rain and snow water. The loss generally was a 1 ¼ to 2 per cent. Also, the interior of the heaps often were unchanged as a result of the roasting. Critics would argue that the roast beds were inefficient when compared with a god shell furnace.
Of course, there was the ever present sulphur smoke. The damage caused by the smoke helped prompt Norway to abandon the roast heap practice while it still was a fact of life in Sudbury. Mond experimented with alternatives, likely borrowing from the Norwegian experience. Mechanical roasters were used and at one time they used the roast bed only during the winter months.
For the residents of Copper Cliff, the establishment of O’Donnell significantly improved living conditions. By 1929, with construction of the new smelter, complete with Nichols – Herreschoff mechanical roasters, the days of the open heaps were drawing to a close. Henceforth sulphur fumes would pass up the big stacks.
Gary Peck is a retired Sudbury high-school teacher with a passion for history.