Pirólise de resíduos de borrachas do setor de mineração para a produção de combustíveis: estudos em escala piloto

Abstract

In this work, the pyrolysis of three different rubber wastes from the mining sector was studied on a pilot scale, i.e. mill parts of nominal composition of styrene and butadiene rubber (SBR), screens and conveyor belts with nominal composition based on natural rubber and butadiene (NR/BR) and offroad tires with a complex composition (mixture of natural rubber, nitrile, butadiene and styrene-butadiene) at temperatures of 450, 600 and 800°C. The reactions carried out at 450°C showed incomplete pyrolysis, and at 600 and 800°C the rubber waste converted entirely in three products: 15-25% gas, 42-44% solid and 34-45% liquid. Gas chromatography analyzes (CG) of gaseous products showed mostly the presence of C1 hydrocarbons -C4 with power values lower calorific value (PCI) equal to 8,496 and 7,325 kcal kg-1, similar to liquefied petroleum gas (LPG). Analysis of solids obtained by elemental analysis of carbon, hydrogen and nitrogen (CHN), atomic emission spectrometry with induced plasma (ICP-AES) Spectro Ciros CCD for sulfur determination, gravimetric thermal analysis and differential (TG/DTA), fixed carbon, ash, volatiles showed the presence of 72-89% carbon with 2% sulfur. Analysis of the liquid products by gas chromatography coupled to mass spectrometry (GC-MS) indicated the presence of complex mixtures of hydrocarbons mainly up to C20. The NR/BR and tire samples produce liquids with a concentration of aromatic compounds close to 50%, while the SBR sample results in the formation of a liquid with a concentration close to 87%. The mixture of this liquid fraction obtained by pyrolysis (without any purification) with a commercial diesel in proportions of 0.5, 1 and 3 vol% showed that no fuel quality parameter defined by the ANP (National Agency for Petroleum, Natural Gas and Biofuels) was significantly changed.