Presentation on theme: "King River Tasmania Copper Tailings Remediation. Background Macquarie Harbour is Largest Estuarine System in Tasmania 1893 – 1994 100 million tonnes of."— Presentation transcript:
King River Tasmania Copper Tailings Remediation
Background Macquarie Harbour is Largest Estuarine System in Tasmania 1893 – million tonnes of Deposited Tailings from Copper Mines Copper Concentrations a high as 2000 ppb
Background cntd…….. Two major Harbour Inputs 1.Gordon River – Relatively Clean 2.King River 100 m tonnes Tailings 10 m tonnes Top Soil 1.4 m tonnes smelter slag Deposited Sediments and Tailings on River Banks and Delta Mouth
Effects Increase in Sedimentation Increase in Toxic Metals Concentration High Tailings Deposits Related to High Sedimentation Copper mineral replacement in bones
Action Taken Closure of ‘Mt Lyell Mining and Railway Company’ in 1995 Mt Lyell Remediation and Research and Demonstration Program Joint Program between – Supervising Scientist Australia – Department of Environment and Land Management
Tailing Dam Construction Tailings Dam on Queens River Catch 22 – Tailings Stopped – River Acidity Increases
Problems 100 million tonnes of Copper (Cu) tailings dumped in river over 100 years causes many problems: The impact on water quality in the lower King River. Reduced amenity for local residents and visitors due to Dust storms Poor navigation. Poor aesthetics resulting from dead rainforest vegetation next to the river.
Remediation Options Four Possible Strategies : Do Nothing Doesn’t address any of the environmental problems Removal/Relocation Of The Tailings Dredging Use Of Explosives On –Site Stabilization Surface Area Reduction Dynamic Compaction Combination of all 3
On-Site Stabilization Number Of On-Site Stabilization Options Volume and nature of the tailings make a number of these options unrealistic due to: Cost Technical details Vitrification Oxidation/Reduction Solidification Capping River Diversion
Vitrification Transformation of Copper tailings to three types of glass by intense heating. Large volume reductions. Solidification Conversion of liquid/semi solid waste to none toxic solid. Economically low cost
Capping Requires significant engineering works to ensure success. Covering tailings with imported material. Costs of hundreds of millions of dollars rule it out as a viable option. River Diversion Idea is to divert the river away from the contaminated delta area. Far too costly to be seriously considered.
Surface Area Reduction Dynamic Compaction Compaction of tailings reduces surface area Reduces area interface with river Therefore less chance of tailings entering river flow.