El medio ambiente en la minería

183 MATTI KOPONEN Besides the well-known flash smelting method, Outokumpu can offer many other efficient and environmentallysound technologies, for example in mining and oredressing, ferrochromium production, stainless steel production, power generation, treatment of hazardous wastes, and surface treatment. The effi– cient and in most cases energy saving processes can be answers to the more stringent environmentallegislation in the future. W. FLASH SMELTING - TECHNOLOGY FOR TOE FUTURE The flash smelting process was developed over 40 years ago by Outokumpu researchers to save electric energy in smelting of sulphidic copper con– centrates. Today this method has been applied in 35 smelters around theworld. Latent heat of the concentrates containing sulphur and iron generates the energy for the process. Gases from the smelting are rich enough in S02 to be technicalIy removed and converted to sulphuric acid with a very high recovery rate. Recent development such as oxygen enriched process air and the new flash converting process make it possible to get continuous smelter gas flow with a much higher sulphur concentration (up to 40% S02). This means that a high conversion rate, better than 99.8%, can be obtained in the acid production. In Outokumpu's Harjavalta smelter and acid plant in W. Finland, S02 emissions totalled 5,200 tonnes in 1991. That is 1.9% of sulphur in the process feed or 0.04 ton S02lton ofmetal. The next renovation step wiIl give 0.02 ton S02Iton ofmetal, which means that the oIdest flash smelter in the world wiil be one of the deanest. Today many non-flash smelters operate at the leve} of 2-3 ton S02lton of metal. In a new sme1ter atmospheric losses of sulphur can easily be reduced lo less than 1 % ir this technology is used. At the Harjavalta Plant, Outokumpu has an on-tine monitoring system for S02 emissions. Besides the plant's management and process operators, cityofficials in town can See the emission situation on their computer screens which are linked to the Outokumpu system. Flash smelting technology, once developed to sav~ energy, is today known as one of the most environmentalIy sound technologies in metallurgy. It can comply with the most striet controls on emissions of sulphur dioxide and provide good working conditions for smelter personnel. About one third of the world's copper is produced using Outokumpu's flash smelting technology.