USE OF BIOMASS ASHES AS AN ADDITION TO RED CERAMICS

摘要

The open-air burning of biomass wastes is one of the most serious environmental problems in continents such as Africa and South America. Brazil, in particular, has a tradition of burning leftovers from deforestation and agricultural crops, which generate huge amounts of ashes. In Campos dos Goytacazes, north of the State of Rio de Janeiro, sugar cane plantations are normally burnt to make it easy for the collections of the stalks. The resulting ashes usually fall down as a "black snow" in urban areas. The sugar cane bagasse is also burnt in boilers to generate power. This work has for objective to recycle biomass ashes by incorporation into red ceramic body. Characterization of the ashes was done by X-ray diffraction and chemical composition. After that, clay mixtures with 0, 5, 10, 15 e 20% of ashes were prepared. Specimens were fabricated by extrusion and then fired in an industrial furnace at 970°C. Solubilization and leaching tests were also performed. The results showed that the ashes are predominantly composed by quartz. The degree of immobilization of potentially toxic metals was considered satisfactory according to Brazilian norms. However, the ash incorporation caused a detrimental effect on the mechanical strength, which was attributed to the large particle size of the quartz.