1 Investigation of the Possibilities for Reduction of Ash Melting Problems in Biomass Combustion Petar Gvero 1* 1 Faculty of Mechanical Engineering University of Banja Luka, Banja Luka, Bosnia and Hercegovina email: petar.gvero@mf.unibl.org Tatjana Botic 2 , Dijana Drljaca 2 , Alaksandra Sinik 2 , Dajana Dragic 2 , Slobodan Rakulj 1 2 Faculty of Technology University of Banja Luka, Banja Luka, Bosnia and Hercegovina email: tatjana.botic@tf.unibl.org ABSTRACT Biomass use for energy purposes is an actual issue from different aspects, as economy, technologies used, combustion specifics, environmental issues, etc. Different biomass types are available on the market today, and due to their physical and chemical specifics, their behaviour in the furnaces is very diverse, from type to type. One of the problems related to biomass combustion is ash behaviour in the furnaces, and it is one of the key limitations for its use. This paper presents some of the experimental results related to combustion of pellets produced from wood, straw, and wastes from medical herbs production as well as some laboratory experiments related to use of solvents with the aim to eliminate some alkali elements from biomass before combustion process. In the pellet combustion experiments emissions of combustion products were measured, and after that analysis of the ash samples was performed. Measurements were performed on pure pellet samples and then on the samples to which some percentage additives were added (1 and 3% comparing to dry mass). Additives as kaolin, bentonite and clay, were used to improve ash melting characteristics. The results achieved from the analysis, shown different behaviour of different type of pellets during combustion process, and their reaction on additives use. It is also shown, that of diluted solutions (as hydrochloric acid) has an influence on porosity of lignocellulose materials and thus on heat transfer characteristics inside of fuel particle and combustion efficiency. It was concluded that some of the applied additives can be recommended because they had positive influence on the ash behaviour as well as some partial influence on the emissions of combustion products. KEYWORDS Biomass, pellet, ash melting, alkali, leaching, additives * Corresponding author