Technical innovation spurred the development of Sudbury, Ont., as the world’s premier mining and metallurgical centre. Louis Secondo Renzoni, as a chemical scientist working on the nickel refining operation of Inco Ltd. for more than three decades, did much to further the company’s fortunes and those of the entire industry. Particularly noteworthy was his work to reduce sulphurous emissions which, at the same time, improved the recovery of economic minerals.

Renzoni was born in 1913 in Copper Cliff, Ont., but when he was just seven months old travelled with his mother to Italy where the outbreak of the First World War in 1914 delayed their return for six years. Back in Canada, Renzoni eventually enrolled at Queen’s University to study chemical engineering. He earned a B.Sc. in 1935 and an M.Sc. in 1936, then worked briefly in a Brantford consulting firm’s laborator before by joining Inco’s principal electrolytic nickel refinery at Port Colborne, Ont., in 1937.

He soon became the leader of a small group of professional researchers whose main task was to develop a substitute for the conventional electrolyte used in the process of electro-refining nickel. By 1941 the process was in the pilot state, but the Second World War created a demand for cobalt and the researchers were asked to develop a cobalt recovery system. Within a year, a new cobalt recovery process was in full-scale operation. The Port Colborne refinery was able to recover more nickel without increasing plant size or power requirements, while at the same time capturing the elusive cobalt.

In 1948, Renzoni returned to Copper Cliff as assistant superintendent of research and development. Of the many projects undertaken, one innovation involved the casting of nickel matte into sulphide anodes for direct electrolysis, thereby avoiding the need to grind, roast and smelt ore to produce nickel metal anodes. The project was developed in time for installation in Inco’s newly built, fully integrated nickel mining and processing operation at Thompson, Man., in the early 1960s.

Also in the 1960s, Renzoni led a drive to reduce sulphur dioxide emissions at the company’s Sudbury operations – the first major effort to manage the problem of high sulphur content in the rich Sudbury ore. This involved separating out a high-sulphurbearing mineral called pyrrhotite. It allowed the company to recover more elements and produce more useful commerical products from its ores while at the same time reducing its sulphur dioxide emissions.

In 1972, Inco’s Super Stack was built to disperse sulphur emissions beyond Sudbury. It was the single most important factor in improving Sudbury’s air quality, but there were several other components of the project incorporated under Renzoni’s direction which, in total, improved the capture of sulphur in the ore and reduced sulphur dioxide emissions by at least 35%.

Renzoni is recognized around the world as the most knowledgeable scientist in the nickel refining business and Inco, years after his retirement in 1976, is still benefiting from research done under his direction.


Robert C. Stanley was the driving force that built Inco into the largest nickel company in the world and one of the world’s most successful mining and metallurgical enterprises. Sudbury, Ontario, with a complex developed around eight mines, and Thompson, Manitoba, with it’s large mining and processing complex, are two of a number of communities whose fortunes have gone hand in hand with those of Inco.

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