Study on the environmental effects of heavy metals in coal gangue and coal combustion by ReCiPe2016 for life cycle impact assessment

During coal and coal gangue combustion, many heavy metal pollutants are emitted and cause serious environmental problems. In this paper, the environmental effect values of As and Pb emission during coal gangue and coal combustion in the 330 MW pulverized coal boiler, 50 kW circulated fluidized bed boiler and laboratory were calculated by ReCiPe2016. The results show that when coal combustion in 330 MW pulverized coal boiler, the environment effect values of As for bottom slag, fly ash and flue gas are 3.28×10^-6, 2.68×10^-5 and 3.89×10^-3 respectively; while the environment effect value of Pb for bottom slag, fly ash and flue gas are 8.57×10^-6, 6.00×10^-5 and 4.83×10^-2, respectively. The environmental effects of As and Pb in bottom slag are lower than those in the fly ash; and the environmental effects of As and Pb on air are higher than those on soil. Moreover, when coal combustion in the 50 kW circulated fluidized boiler, the effect values of As and Pb in fly ash on environment are 3.26×10^-5 and 1.28×10^-4; and the effect values of As and Pb in bottom slag are 1.16×10^-6 and 1.43×10^-5 respectively. The results also show that when coal gangue combustion in the laboratory, the effect values of As and Pb emission increase with increasing of the temperature; and the proportions of total environmental effects of As and Pb on air are higher than those on soil. Besides that, this study also indicates that the effect of Pb emitted into environment is higher than that of As at the same conditions during coal combustion both in circulated fluidized boiler and pulverized coal boiler. The results may provide basic data for predicting the environmental effects of As and Pb during coal gangue combustion in circulating fluidized bed for life cycle impact assessment.