Water Journal : Water Journal May 2012
water in mining refereed paper technical features 74 MAY 2012 water be somewhat controlled through membrane filtration, but in one instance at Dalby where turbidities reached 100 NTU an additional lamellae settler was necessary. The CSG water was drawn directly from the gathering system long before it reached the storage dams. There were a lot of innovative engineering features to get this system to work, by degasifying the water using a chimney stack just before the clarifier. The only challenge was that the gathering system could not supply enough water; • Adequate screening to protect the membrane fltration system; • A granular activated carbon pre-flter was provided at Moranbah to remove oil from the raw water supply; In some instances the client has provided the feed pumps, biocidal dosing and iron removal at the feed intake; • Either chlorination, chloramination and non-oxidising biocides to eliminate bacteria in the water; • A specifc antiscalant is necessary where levels of iron, fluoride and silica become an issue, particularly calcium fluoride, and barium sulphates at high recovery. Key Features of the Reverse Osmosis Plant The design of the reverse osmosis membrane plant includes: • The incorporation of seawater membranes and back pressure on permeate ports to ensure correct flux rates across stages and optimal recovery; • Cross-flow membrane filtration with conservative flux rates and automated cleaning system to handle organic/biological fouling. In most of the plants the micro-filter was provided by Pall Australia and at Moranbah the membrane modules were provided by DOW; • Energy recovery turbines and boost pressure on third-stage operation; • Variable speed control for the high-pressure feed pump to allow plant stabilisation; • Pressure transmitters to measure pressure across each stage and flow meters on all permeate connections for monitoring of flow production; • In some instances the use of duplex stainless steel where chloride concentrations were high and outside the range of normal stainless steel 316; • Given the high recoveries necessary antiscalant is tracked and measured. Aquatec-Maxcon provided a number of containerised Figure 5. Typical schematic for CSG scheme. Figure 6. Site photo of the containerised RO system. Plant layout at Dalby. Plant layout at Talinga. Plant layout at Moranbah.
Water Journal July 2012
Water Journal April 2012