INCORPORATION OF INDUSTRIAL WASTES IN WOOD PELLETS M Ferreira (1) , M Vilarinho (2) , F Castro (3) , A Pinto (4) , P Ferreira (5) , J Teixeira (6) Department of Mechanical Engineering, University of Minho Campus de Azurém, 4800-058 Guimarães, Portugal (1) ef@dem.uminho.pt (2) candida@dem.uminho.pt (3) fapsc59@gmail.com (4) apinto@cvresiduos.pt (5) pedro@dem.uminho.pt (6) jt@dem.uminho.pt ABSTRACT: The present work evaluates the incorporation of industrial wastes (Refuse Derived Fuel-RDF) into biomass for pellet production. Its influence on parameters such as pellet production, combustion and gas emissions was studied for up to 10% of residues incorporation. This approach also deals with the diverting of industrial waste from landfills. The main objectives were: increasing the heat value of the final product, diverting industrial residues with energy potential from landfill and assess the quality of different types of pellets with incorporation of industrial residues. Its implementation was carried out in three phases: selection and characterization of the different industrial residues, production of pellets from different mixtures of wastes and combustion tests. For this purpose a comprehensive characterization of the pellets, the gaseous emissions during combustion and the chemical characterization of the resulting ashes was carried out. The study has shown that the application of industrial residues is a promising route for their incorporation in pellets which should be balanced by the reduction of wastes for landfill. However a few problems were identified: higher difficulty in pelletizing and likely excessive wear of the pellet mill for some of the residues; combustion equipment requiring air supply adjustment and higher ash contents. Keywords: Pellets, RDF, biomass 1 INTRODUCTION Pellets are a source of renewable energy. It constitutes a flexible way to use wood residues (mostly sawdust) and reduce the greenhouse emissions that other energy sources produce. The continuous rise of electricity and fossil fuel prices, and their depletion, is a strong incentive on the demand of pellets as a heating fuel for both domestic and, increasingly, industrial applications. The former requires very high standards regarding their quality with strong emphasis in the ash content (below 1%); the easy of use is paramount to the consumer. However, those for large scale industrial applications require not so stringent standards. In addition the increasing demand for such fuels (due to the cost effectiveness and policies promoting the use of renewable sources) has opened the interest in using other forms of raw materials for pellet production. One common route is the use of alternative sources as the sole raw material. That is the case of fast growing energy crops, like myschanthus or canary grass (Larsson et al, 2008); agriculture residues such as olive bagass or other food products (Gonzalez et al, 2004). Also, the use of municipal solid wastes in pellets has been a promising alternative for its energy valorization (Marsh et al, 2007). The other route includes some kind of blending in a wood based matrix of materials such as pruning ends bark and coal (Alzate et al, 2009), amongst others. In this approach, urban wastes and industrial residues may play an important role. Furthermore it may provide an alternative process for disposal of low toxicity wastes reducing the amount of landfill material and enhancing, in some cases, the heat value of the pellets produced. This contribution to the reduction of landfill material has been highlighted by Grammelis et al (2009). As far as the upstream industry is concerned, their wastes may