An evaluation of mercury emissions from the chlor-alkali industry in China

摘要

The present status and the history of chlor alkali industry using mercury as cathode in China has been studied. Quantitative mercury emission has been estimated. At present, 17.5%—20% of the consumed mercury is released into water, 49.1%—53.3% of the Hg is discharged to the brine system outside the plants. 10%—14% of the Hg is emitted directly to the atmosphere, 5 3%—6 7% enters waste materials. The chlor alkali industry in China discharged about 17 tons every year. The total amount of mercury released by the chlor alkali industry in China is estimated to be 1400—2700 tons since 50’s. With the result of improved technology and more strict environmental regulations started in late 1970’s, chlorine plants reduced their mercury loss factor from 0 5? ? 4 kg/t NaOH before 1977 to 0.16—0.18 kg/t NaOH in 1997. The number of mercury cells in alkali plants was also reduced. In 1998, China is planning to finish the history of producing chlorine and caustic soda using the mercury cell process in the near future. How to deal with the emitted mercury will remain a main problem.