Mechano-Noncatalytic Wet Treatment Method for Extracting Ash from Biomass at Room Temperature and Its Effect on Ash Behaviors

Replacing coal with a renewable energy source, such as herbaceous biomass in the fired power industry, can effectively reduce carbon dioxide emissions in the environment. However, herbaceous biomass contains higher levels of ashes (especially potassium and chlorine) than coal and woody biomass, which cause operational problems and release fine particulate matter during combustion in power plants. Existing methods use strong catalysts, toxic solvents, and heat for extracting ash from biomass. Here, we propose a simple mechano-noncatalytic wet treatment to remove ash from biomass using only water at room temperature. The potassium and chlorine contents in the ashless biomass were reduced by 96.90-98.82 and 73.92-98.56%, respectively. Although our method used only water and mechanical energy, it had an ash leaching ratio similar to that of previous treatment methods that use harsh conditions. The leaching of alkali metals inhibited the adhesion of ash particles and the formation of high-melting-temperature minerals. Furthermore, the treatment effectively mitigated the ash corrosion behaviors. Our study demonstrates that herbaceous biomass can successfully replace coal in power plants after it is pretreated with a sustainable ash extraction method.