【Paper】

Recovery of Abrasive Grains by Combustion/Thermal Degradation of Waste Grinding Wheels in O2/N2 and Steam/N2 Atmospheres
Kensaku Sasaki*, Yoshihiro Kojima*, Hitoki Matsuda*, Yoshiharu Terada** and Katsuhiro Kano**
* Research Center for Advanced Waste and Emission Management, Nagoya University
** Noritake Co, Limited
† Correspondence should be addressed to Hitoki Matsuda:
Research Center for Advanced Waste and Emission Management, Nagoya University
（Furo-cho, Chikusa-ku, Nagoya, Aichi, 464-8603 Japan）


Abstract
In order to recover abrasive grains from waste grinding wheels（phenolic resin and abrasive grains）, combustion/thermal degradation of waste grinding wheels was carried out in both an O2/Ns2（20/80％）atmosphere and a steam/N2 atmosphere at 800℃ in a batch reactor. In the present study, two kinds of grinding wheels were used: sample A consisted of Al2O3/SiC/Phenolic resin（70/20/10 wt％）, and sample B consisted of Al2O3/Phenolic resin/FeS2/K2SO4/KCl/CaO/Glass fiber（53/7/25/7/2/2wt％）.
Through combustion at oxygen ratios of 1.1-2.6, carbons of the phenolic resin in both samples A and B were converted almost completely to CO2 in 5-20 minutes. It was confirmed that the main abrasive grain component, Al2O3, could be recovered from the solid residues. In addition to CO2 generation, gases such as CO, lower-hydrocarbons, and NOx were detected during the thermal degradation of sample A in an O2/N2 atmosphere. In the thermal degradation of sample B, SO2 and HCl were detected among gases such as CO2 and CO. Behaviors of CO2 and CO formation were observed in the thermal degradation of sample B in the stream/N2 atmosphere similar to those in the thermal degradation in the O2/N2 atmosphere. In this case, lower-hydrocarbons, CS2 and H2S were detected along with CO2 and CO. However, the main abrasive grain, Al2O3, was found to be recoverable through thermal treatment in the steam/N2 atmosphere.


Key words: waste grinding wheel, phenolic resin, abrasive grain, combustion, steam heating