El medio ambiente en la minería

131 T. KIMURA& KUROKAWA Modification and Change olOperatwn Results Figure 2 shows the change in treated copper concentrate, matte grade, produc– !ion of refined anodes, 802 strength ofsmelter offgas, production ofsulphuric acid and number of employees al Toyo smelter and refinery. The introduction of three oxygen¡,lants with a capacity of 7800 Nm 3 IR at 90% 02 installed in 1982, 2000 Nm IR at 93% 02 in 1988 and 1989, respectively, and several modifications enable the smelter to treat two times tbe original capacity of concentrate witb the same number of furnaces and a significantly lower number of employees. Table 5 indicates several main modifications resulting in high productivity and less pollution carried out in these yeacs. TableS. Recent Main Modífications Sectlon Years Modlflcatlons Flash Furnace 1981 Fuel conversion to pulverlzed coa! 1982 Oxygen enrichment In the blast hot alr 1985 Hishikarl gold ore treatment as flux 1990 Replacementof the radiation saetíon of the flash fumace waste heat bailer Converter 1978 Anode scrap charge by the scrap conveyor durlng blowing 1981 Expansion of the shell (23QtJcycle from 18Qt/cycle) 1982 Oxygen enrichment in the blast air Anode Furnace ! 1986 Expansion of the shell (470 I/cycle from 370 t/cycle) 1989 Reductant conversion to propane gas Acid Plant 1977 Oesulfurlzation of the fugitiva gas 1978 Double contact system 1989 Change trom irrigation cooler lo &hell & tuba cooler Arsenic Plant 1981 Copper atsanate plant i 1983 Arsenlc trioxlde plant