The interactions between quartz sand and wood, which was doped with either K or Na salts, were investigated in a lab-scale, fixed-bed reactor under either a steam gasification or a combustion atmosphere at 900 degrees C. For the cases of the potassium/sodium phosphate salts, the interaction was found to be melting induced, while for the cases of the other salts, it was found to be coating induced. Large agglomerates were found to have already been formed during the early stages of steam gasification for the wood samples doped with potassium/sodium carbonate and acetate. However, the agglomerates obtained under the combustion atmosphere were found to be insignificant for the wood samples doped with potassium/sodium chloride. Both the reaction atmosphere and the types of salts were found to affect the formation of potassium/sodium silicates in the agglomerates and the interactions between the quartz sand with gaseous K or Na significantly.