Behaviour of different industrial waste oils in a pyrolysis process: metals distribution and valuable products

In the present paper, the results obtained in the pyrolysis of four industr ial waste oils (automotive, hydraulic, machine and cutting oil) are shown. The pyrolysis has been carried out at atmospheric pressure and 600 degrees C. The continuous injection of the samples was into the bottom part of the reactor using a pump. Liquid and gases fractions have been analysed, organi c products by gas chromatography and metals concentration by Graphite Furna ce Atomic Absorption Spectrometry (GFAAS). The gases obtained are mainly fo rmed by methane and light olefins, C-2-C-4, and the liquids contain an arom atic fraction of high industrial value. The behaviour of metals was also ve ry different from one oil to another. Lead was the most affected metal in a ll of them, with a decrease ratio (concentration before and after the pyrol ysis) from 165 for machine oil to 32 for the hydraulic oil. Pb, Cr, Cu, Ni, Pb and V were identified and quantified in each fraction. The results show that the automotive and machine waste oils are the better ones concerning the liquid yields. However, the hydraulic and cutting oils show a high conv ersion to gas products. The relationship between the type of waste oil and the products obtained is discussed. (C) 2000 Elsevier Science B.V. All righ ts reserved.