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Technical Papers
Figure 2. Mammoth Water Condenser, Coolgardie 1896. In 1967, West Australia’s Mammoth Iron Ore project installed two 900m3/ day Weir-Westgarth multiple effect flash (MSF) units (Figure 3) at the heart of its operations at Dampier in the north-west of Western Australia (WDR, 1967). Hamersley Iron (now Rio Tinto), the company formed to develop the Mt. Tom Price hematite ore resource, built the desalting plant at the port of Dampier. The desalted water was used for domestic, dust suppression and shipping requirements, in addition to ore processing. The plant was decommissioned in the 1980s.
The number of desalting plants in Australia grew rapidly in the 1990s, with numerous small desalination plants commissioned for both mining and oil and gas-related projects. There are now more than 300 small reverse osmosis plants servicing remote mining, oil and gas, and power station sites in Australia. It is in the new millennium, however, that the planning and installation of medium to large desalination plants for industrial and mining purposes, along with municipal purposes, has been more widely adopted. Some of these installations and planned plants include: • Burrup Fertiliser GTL (Burrup Peninsula, Western Australia) mechanical vapour compression (MVC) plant, 3 x 1.5 ML/d MVC units, commissioned in 2004; • BHP Billiton (now Queensland Nickel) Yabulu Nickel Refinery BWRO plant (Townsville, Queensland), 10 ML/d, commissioned in 2005; • BHP Billiton (now First Quantum Minerals) Ravensthorpe Nickel Project multiple effect distillation (MED) plant (Ravensthorpe, Western Australia), 7.2 ML/d, commissioned in 2006; • Citic Pacific Mining Sino Iron project, Cape Preston SWRO Plant (Cape Preston – Western Australia), 140 ML/d, commissioned in 2013; • MCC Mining, Cape Lambert Desalination Plant. SWRO Plant up to 120 ML/d, definition stage, on hold;
Figure 3. Hamersley Iron MSF Desalination Plant (Courtesy Weir Westgarth).
• Grange Resources Southdown Magnetite Project, Cape Riche Desalination Plant (Cape Riche,
APRIL 2015 WATER
DESALINATION
The most famous of all the woodfired stills, and the largest desalination plant in the world at the time, was the Mammoth Water Condenser (Figure 2), which produced 455m3/d from 546m3/d of feed water, using about 100 tonnes of firewood. The calculated specific energy consumption (SEC) of this plant is 989kWh/m3, assuming wood-burning delivers 4.5kWh of energy per kilogram of wood. The still converted brackish water to freshwater at a recovery of 83%. In contrast, a modern brackish water reverse osmosis (BWRO) plant would produce water at a SEC of around 1kWh/m3, a thousand-fold improvement.