REUTILIZAÇÃO DE AREIA A VERDE DESCARTADA DE FUNDIÇÃO LIGADA COM Na2SiO3.XH2O/CO2 NA PREPARAÇÃO DE MOLDES NÃO PERMANENTES

Abstract

The manufacture of metal parts by molding and molded by the process in the green sand (sand base crowded with clay) is widespread in industries for its low cost and operational flexibility. A major advantage is that the materials can be reused in new molding cycles. However, when the liquid metal comes in contact with the mold, causes disabling clay locally, generating inert materials that focus on the sand and limit long cycles of reuse. Thus, there are surplus sands by adding new primary materials and the consequent need for disposal to maintain the constant flow of materials. This excess is a liability that is usually discarded in landfills. This study sought a solution to this environmental waste, by reuse in the actual molding process using the sodium silicate (Na2SiO3.XH2O)/CO2, as binder. The properties obtained from samples with waste foundry sands (WFS) and with the new green sands were compared to verify the real potential for reuse WFS and the effect of its inert components and additives. For this purpose it was evaluated the mechanisms involved in the interaction with the green sand silicate before and after reaction with CO2 in the range of 0 to 20% (by weight) mixed. Mechanical properties were evaluated before and after gassing with CO2, both with WFS and with its primary components. In this study, for microstructural characterization techniques were used for X-ray diffraction, optical microscopy and MEV/ EDS. The results showed mutually dependent mechanical properties, the morphology of the silica gel coating on the sand grains, and the composition of the mixture used.