Experimental and modeling study on the volatilization of arsenic during co-combustion of high arsenic lignite blends

Abstract

The co-combustion experiments of a high arsenic lignite (GX coal from Guizhou) and three low arsenic bituminous coals were conducted on an isothermal system at 600–1100°C with different blending ratios. The mass loss and mass loss rate of arsenic were studied and compared with the weighted average values. Results show that the arsenic content in blended coal has additive property. The volatilization characteristics of arsenic in blended coals are between two single coals and decrease with increasing blending ratio of bituminous coal. While due to the larger volatile matter in lignite, the mass loss ratio and mass loss peak of arsenic in mixed coals are both higher than the weighted average values. Considering the effects of temperature, coal blending and coal type, the volatilization model of arsenic during co-combustion of one high-arsenic lignite(coal A, blending mass ratio x) and one bituminous coal(coal B) at 600–1100°C was established. The expression is VT=xVAT+(1-x)VBT+η×(11+e-0.015(T-900)+0.1)x(1-x). The larger difference between bituminous and lignite coal, the greater value of η. Model calculations fit the experimental results well, which provides a reference for the prediction of arsenic volatilization in blended coals.