Arsenic release and transformation in co-combustion of biomass and coal: Effect of mineral elements and volatile matter in biomass

After the co-combustion of tobacco stem/black bean straw/wheat straw/millet straw/corn stalk/rice straw and coal, it was found that all tested biomass in this study could inhibit arsenic release, but only rice straw promoted arsenic release. When the acid washed biomass was mixed with coal during combustion, the release of arsenic increased. When mineral metals (Na, K, Mg, Ca, Al and Fe) and Si elements were added to the coal, the mineral metals inhibited arsenic release. However, the release of arsenic was increased when the silicon content in biomass was high. The volatiles in the biomass also promoted the release of arsenic during co-combustion. The arsenic in the ash generated from co-combustion was mainly in the sulphide-bound state. Co-combustion of biomass and coal reduced the occurrence of an exchangeable state in the ash, and also significantly reduce the possibility of leaching.