During 1924-25 the Mount Elliott Company and Hampden Cloncurry negotiated a scheme of amalgamation but this fell through when Mount Elliott acquired the Mount Cuthbert properties. In 1926 Hampden Cloncurry conceded defeat and offered its assets for sale by tender, most being acquired by Mount Elliott, who finally gained control of virtually the entire Cloncurry copper field and belatedly fulfilled William Henry Corbould's vision of 1909 for amalgamation. But it was too late: funds were exhausted and prices were low. The company decided to use the Henry Squarebrigs Mackay's new process to utilise the low-grade ores of the district. This was a new form of electrolytic smelting. In 1926 the company started building the first per year unit of a large electro-chemical copper treatment plant at Cloncurry on the outskirts of the town adjacent to the Great Northern railway line. This comprised crushing, roasting furnace, leaching vats and a cell house section and was completed in April 1927. It was the first plant of its kind ever built and Mackay supervised its construction at Cloncurry. The convert|18|by|18|mconvert|1.5|mconvert|30,000|impgalA£|128,000
Description
The place contains the remains of an electrolytic reduction plant comprising five groups of structures. The primary crusher and ore dump group situated to the south comprise an ore dump site, earth loading ramp, concrete surfaces, tanks and building foundations. An iron flotation unit is located on the site. To the north are the concrete mounts and foundations of a wedge roasting furnace. These structures include a flue and iron chimney base and a vertical boiler alongside a concrete tank. Adjacent to the west is a large concrete leaching vat square and in height, which was originally equipped with a gantry crane. The walls of the vat are supported by heavy concrete buttresses. To the north are four circular leaching vats of concrete construction each in width and in height. The northern group of structures is located alongside to south of the Cloncurry - Mount Isa railway. This group comprises concrete surfaces and foundations of the electrolytic works, a rendered brick flue and base of an iron chimney and three concrete tanks each approximately by in depth. The fifth component of the site is the foundations of a former laboratory building, constructed with mud brick walls with cement render on exterior and interior surfaces. Plant equipment at the site includes a vertical boiler and flotation unit .
Heritage listing
Mount Elliott Company Metallurgical Plant and Mill was listed on the QueenslandHeritage Register on 17 June 2003 having satisfied the following criteria. The place is important in demonstrating the evolution or pattern of Queensland's history. Its construction testifies to the optimism held by the company for a centralised modern plant to service all their scattered ore reserves across the region. The place demonstrates rare, uncommon or endangered aspects of Queensland's cultural heritage. The Mount Elliott Company Metallurgical Plant is significant in Queensland's history as the only recorded surviving evidence of an early electrolytic plant. The laboratory remnants associated with the plant are architecturally uncommon, being made of ant bedadobe bricks. The place is important in demonstrating a high degree of creative or technical achievement at a particular period. The process was Henry Squarebrigs Mackay's own invention and the plant was designed in London. It was the first plant of its kind ever built and Mackay supervised its construction at Cloncurry.
