The effect of the addition of chemical materials on the sintering of biomass ash

Abstract In this work the use of chemical materials (additives) in order to reduce the biomass ash sintering tendency is investigated. A total of seven additives (kaolin, limestone, lime, dolomite, calcined dolomite, ophite and alumina) and silica utilised as reference material were mixed in different proportions with the ash of five different biomasses, and then a laboratory sintering test was performed on the mixtures to determine the effect of the additives on the sintering. The biomasses studied in this work were: thistle biomass, brassica carinata biomass, barley straw, almond shell and orujillo (olive oil extraction residue). The sintering decrease among the additives was studied using X-ray diffraction. Kaolin, lime, calcined dolomite and ophite are proved to be suitable to reduce the biomass sintering in all the considered cases. Dolomite, limestone and, particularly, the tabular alumina, offer poorer results. The dilution of the biomass ash is considered the main process involved in the decrease of the sintering for most of the additives, with the exception of kaolin whose chemical reactions could be more important than the dilution effect.