Study on co-combustion characteristic of coal and industrial solid wastes and the migration behavior of heavy metals

Co-combustion with coal is a potential disposal option for industrial solid waste (ISW). This work investigated the combustion characteristics and heavy metals emission behaviors during coal and ISW co-combustion process. The moderate blending ratio (below 20%) of ISW improved the combustion characteristics of coal, while excessive blending increased the energy potential barrier. The emission of heavy metals was mainly affected by the fuel composition and combustion parameters. The emission of Cd, Pb and As was increased with the increase of combustion temperature. The highest volatilization rates of Cd, Pb and As were 71%, 56.9% and 39.7%, respectively. The blending of ISW inhibited the emission of Cd and As (minimum 61.6% and 23.2%), promoted Pb emissions (maximum 56%), and had insignificant effect on the emission of Hg and Cr. This was attributed to the interaction between some inorganic minerals in the blended fuel with heavy metals. Co-combustion of ISW weakened the environmental mobility of heavy metals and thus reduces the environmental risks. The blending ratio of ISW should be 20% considering the combustion behaviors and heavy metal transformation. These results provide guidance for the resource disposal with low heavy metal emissions of ISW through co-combustion in existing boilers.