Carbonaceous aerosols emission reduction by using red mud additive in coal briquette

Residential coal combustion is a major source of carbonaceous aerosol globally. Clean coal briquettes can be used for pollution emission control. In this study, red mud (RM), a high alkalinity byproduct generated from the Bayer process, was employed as additive in coal briquettes. Combustion tests of briquettes and raw coal were conducted to evaluate the emission reduction effects on PM_2.5 and carbonaceous aerosols. The highest emission reduction rates of PM_2.5, organic carbon (OC), elemental carbon (EC) for bituminous were 37.5%, 13.2%, 82.6% and for anthracite were 31.2%, 11.1%, 30.0%. Total carbon (TC)/PM_2.5 remained stable between raw coal and briquettes while EC/OC was altered significantly (from 0.32 to 0.08 and 0.08 to 0.03 for bituminous and anthracite). Subfractions (in both OC, EC) showed a similar decreasing trend with the increase of RM content, while OC3 and OC4 reduction was not significantly compared to raw coal emission. Regression model showed that volatile matter and RM content are the two most significant (p < 0.01) fuel properties affecting the emission of PM_2.5 and OC. Moisture and RM content influenced EC emission most significantly (p < 0.01). This study demonstrated that RM-added coal briquettes can effectively improve regional air quality.