Simultaneous recovery of acid-soluble potassium and silicon components from biomass combustion bottom ash using pulverization methods

Abstract

The value of biomass combustion ash as a fertilizer can be improved when the potassium and silicon as major elements can be recovered simultaneously. To address this concern, the pulverization and classification is proposed in this study to improve the surface of ash particles to recover potassium and silicon elements simultaneously from woody biomass bottom ash. To this end, ash is ball milled using different ball sizes and pulverization times of 15–60 min, followed by sieving with 150 and 75 µm screen sizes. Pulverized ash obtained using smaller ball diameter produces finer ash particles with 14 % of higher yield in average, 18 % and 25 % higher levels of acid-soluble potassium and silicon, respectively at their maximum level, and 35 % higher of Newton’s efficiency in average compared to produced using a larger ball, indicating that the recovery of potassium and silicon simultaneously improved. A smaller ball separated finer particles containing potassium from the surface of larger particles containing silicon via surface grinding, as indicated by the higher difference in the median diameter of pulverized ash, resulting in ash particles that have a higher recovery of acid-soluble potassium and silicon components.