Rheological Properties and Stability Characteristics of Biochar-Algae-Water Slurry Fuels Prepared by Wet Milling

Abstract

This study was aimed to understand the rheological properties and stability characteristics of biochar-algae-water (BAW) slurry fuels prepared by wet milling. A pine sawdust biochar and a chlorella vulgaris algae were used in preparing the slurry fuels. The BAW slurries were formulated by mixing the biochar, algae, de-ionized water, lignosulfonic acid sodium salt, and then the mixture was ball-milled for various times. The BAW slurries with a constant solid loading of 45 wt % were prepared with varied algae proportion in algae/biochar mixture. The apparent viscosity and stability of BAW slurries were measured. It was found that D50 of the particles of the solid in the slurries decreased with increasing milling time. The viscosity of the slurries decreased first and then increased as milling time increased, reaching a minimal value when D50 of the solid was between 3 and 7 μm. The lowest viscosity of BAW slurries achieved at a given solid loading increased with increasing the algae proportion in the solid. The BAW slurries showed better stability at higher algae proportions due to enhanced flocculation.