Annual Report 2007 - Antofagasta plc

Corporate Social Responsibility continuedCase Study – In the desert: a sustainable responseThe Esperanza project will use sea water for its needsCSR REPORTChallengeThe availability of water in the driest desert of the world is a formidable engineering challenge. At present,water from the high Andean plateau of the Antofagasta region is used mainly in agriculture, with little beingrecycled. There has been a rapid increase in demand for water for industrial and household use and it isessential that new projects develop alternative sources of water supply as well as optimise the efficientuse of water as has been done by most of the large mines.DescriptionSea water will be transported 145 kms by pipeline from the coast to Esperanza which is 2,300 metres abovesea level. The pipeline will run parallel to the one carrying copper concentrate to the coast. Esperanza will alsodevelop a system of thickened tailings which compared to conventional tailings, allows a considerable amountof water to be saved.SupplyAll equipment will be adapted to use untreated sea water in both the mine and plant installations. There willbe a need for fresh water – for example, for human consumption or for washing the concentrate – but thiswill not exceed 10% and will be obtained using two reverse osmosis plants: one on the coast and the otherat the mine. The water contained in the concentrate will also be recovered and re-used, to avoid dischargeinto the ocean.SavingsEsperanza is considering a second innovation related to reducing water consumption in its operationsby introducing the Thickened Tailings System, which is recommended for desert areas with insufficientwater basins.The Esperanza tailings will consist of 67% solid material in a thick pulp made by increasing the consistency ofthe tailings and recovering the water in the thickeners, so that the material is no longer separable. The pulp willthen be dried through evaporation, resulting in a dense, seismically stable deposit that cannot be liquefied.ContextThe Esperanza project, 30 kms from Sierra Gorda and 180 kms from Antofagasta, is located in a desert areacharacterised by low or zero precipitation.Facts and figures• The Esperanza project will transport sea water 145 kms to supply the mine site.• The pumping system must be capable of delivering water from the coast to the project at an altitude of2,300 metres.• Approximately 10% of the transported water will be desalinated for human and industrial use.• Antofagasta’s copper production will increase by 40% from current levels after production at Esperanzabegins at the end of 2010.54Antofagasta plc Annual Report and Financial Statements 2007