Milling of the siliceous underground ores was initially based on gravity concentration by jigs and shaking tables, but Mount Lyell was among the earliest of the Australian mines to investigate and adopt the flotation process developed in Broken Hill, in the first instance as a supplement to gravity methods and later as a complete substitution, with greatly improved grades and recoveries of copper and gold and with subsequent benefits in smelting. The innovative approach in metallurgy continued, for example, in the practice of feeding wet flotation concentrates directly into the blast furnace and providing for a circulating load of flue dust up to 25 percent.

On present indications mining activities at Mount Lyell will be phased out in 1994, ending over 100 years of mining and metallurgical operations, during which the field was technically in the very front rank of the world's copper producers and at one stage, in 1899, it was the largest copper mine in the British Empire, with an output of 9500 tonnes of the metal. Later in its history Mount Lyell was to attain an annual production of 24 000 tonnes. It is a sad fact of history that the great technical success of pyritic smelting was achieved at horrendous cost to the environment in the destruction of a vast area of rainforest and in pollution of rivers; this would not be permissable in contemporary operations.

Mount Isa technology

Similar histories to that of Mount Lyell can be developed for other Australian copper producers, and a number have been recorded in the very extensive technical and secular literature. If one instance had to be selected from the many sources it would surely be Mount Isa, which has dominated the copper scene since the 1930 discovery, in a drill hole adjacent to the outcropping lead-silver-zinc lodes, of the first of several copper ore bodies, and the development of that first ore body during the second World War. Mount Isa is now recognised as one of the greatest mineralized areas in the world, and the operating company has developed major mining, metallurgical and exploration practices and extensive research facilities to service its activities in lead, silver, zinc, copper, gold, coal and other commodities which now extend beyond Australia to Europe, the Americas and the Asian Pacific countries.

Innovations flowing constantly from the research and development facilities at Mount Isa and at the Townsville copper refinery and manufacturing plant include impressive advances over the widest possible range, from aerial and terrestrial exploration and ore reserve estimations, through rock stress analysis and ground support systems including cemented filling, to drilling and firing techniques and haulage systems, to computer simulation and control of grinding and flotation circuits and on-stream chemical and mineral sampling and analysis of concentrator and smelter and refinery products. In addition to advances in these areas the company has pioneered, in some instances with collaborating research bodies such as AMIRA, AMDEL, CSIRO, JKMRC, AAEC and ACIRL* major production techniques such as submerged combustion processes, continuous copper casting, stainless steel cathodes and automatic stripping, new rolling methods, and application of oxygen-free high conductivity copper to electronic components, and optical fibre cable protection.

* AMIRA: Australian Mineral Industries Research Association
AMDEL: Australian Mineral Development Laboratories
CSIRO: Commonwealth Scientific and Industrial Research Organisation
JKMRC: Julius Kruttschnitt Mineral Research Centre
AAEC: Australian Atomic Energy Commission
ACIRL: Australian Coal Industry Research Laboratories

Australian Academy of Technological Sciences and Engineering