March/April 2007

Rich heritage of copper production in Canada

By P. J. Mackey, Xstrata Process Support, Falconbridge, Ontario

Canada has a long and rich history in all aspects of copper production—exploration, mining, milling, smelting, and technology development.The first copper smelter in Canada was located at Bruce Mines, Ontario, where a reverberatory furnace based on the Welsh Process began in 1849 (Kossatz and Mackey, 1989). The plant had a capacity of about 50 to 100 tonnes of copper per year, and operated for about a year before it was destroyed by fire. A new plant, based on roasting and leaching, was then built on the same site and operated until 1875 when it finally closed. Across the country, many other mines were subsequently discovered and opened, and in many cases, generally due to the remoteness of the location as regards to ore or concentrate shipping, captive smelters were built to treat the ore. Usually these plants operated for a period, and most eventually closed. In fact, since 1849, over 50 copper and copper-nickel smelters have been built in Canada and all but the seven operating plants today have closed—generally for a combination of high operating cost, low copper prices, and/or exhaustion of copper ore. The seven plants are: Horne, Kidd, Falconbridge, Copper Cliff, Flin Flon, Thompson, and Trail.The latter began as a copper smelter, hence is included here; since the early 1900s, it has treated lead and zinc materials. The last smelter to shut down was the Gaspé smelter in Quebec, which closed in 2003 due to the above factors.

The average size or output of the copper smelters built in Canada has steadily increased over the more than 150-year period since that first plant at Bruce Mines (Figure 2).At first, the plants were naturally quite small; the average nominal smelter size was only about 1,300 tonnes per year of copper in 1900. By the early 1930s, the average size had increased to 62,000 tonnes per year of copper following the commissioning of the rich Horne mine and smelter in 1927, the Flin Flon facilities in 1930, as well as expansions at the Copper Cliff smelter in Sudbury.By the 1960s to 1970s, the average nominal size had plateaued at about 85,000 tonnes per year of copper. The average nominal size of the present smelters (including Ni-Cu smelters) is just 100,000 tonnes per year of copper. Excluding the Ni-Cu plants, the nominal average of the four copper (only) smelters in Canada is about 125,000 tonnes per year, considerably below the average output of 400,000 tonnes per year of copper for the ten largest (and generally the lowest cost smelters) in the world today. The smaller size of the Canadian plants, coupled with constantly rising costs for fuel, electricity, and labour, is a worrisome trend.

Canadian technology in copper smelting has few equals. Among the first experiments in the world in the flash smelting of sulphide material were tests carried out in the 1920s in Canada, at first on pyrite using a single vertical shaft (Freeman, 1930), a forerunner of the now well-established Outokumpu flash furnace later developed in Finland for copper concentrates involving a vertical reaction shaft and a separate gas uptake shaft (Sarkikoski, 1999). In Canada, flash smelting of copper concentrates was also perfected by Inco (Anon., 1953).The well-known Noranda Process was developed in Canada (Pannell and Mackey,1988), and this process is now used at several plants around the world. The Kidd technology for electrorefining copper was developed in Canada, and this is now widely used at many plants around the world (Laezza, Box, and Scott, 1990).

By keeping costs in check and with continued discovery of new ore bodies, along with technology development, the prospects for Canada’s copper industry would appear bright.

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