Post-harvest processing methods for reduction of silica and alkali metals in wheat straw

Silica and alkali metals in wheat straw limit its use for bioenergy and gasification. Slag deposits occur via the eutectic melting of SiO₂ with K₂O, trapping chlorides at surfaces and causing corrosion. A minimum melting point of 950°C is desirable, corresponding to an SiO₂:K₂O weight ratio of about 3:1. Mild chemical treatments were used to reduce Si, K, and Cl, while varying temperature, concentration, % solids, and time. Dilute acid was more effective at removing K and Cl, while dilute alkali was more effective for Si. Reduction of minerals in this manner may prove economical for increasing utilization of the straw for combustion or gasification.