Melting solidification and leaching behaviors of V/As during co-combustion of the spent SCR catalyst with coal.

• The blending of spent SCR catalyst with coal was proposed. • Spent catalyst blended with coal could promote coal combustion. • The V and As could well solidify in the bottom ash. • The leaching of V and As in bottom ash was very low. The spent SCR catalyst as the hazardous waste would seriously affect the ecological environment and human life. In this study, a new method of spent SCR catalyst harmless treatment was proposed by blending the spent SCR catalyst with coal for combustion. The combustion characteristics of coal blending with spent SCR catalyst, melting solidification characteristics of V/As in spent catalyst, and leaching characteristics of V/As in bottom ash were explored by TG, ICP-MS, XRD, SEM analysis. The results show that the proper amount of spent catalyst blending with coal could promote coal combustion by reducing the ignition and burnout temperature of coal particles due to the catalytic effects of TiO 2. The co-combustion of spent SCR catalyst with coal could well solidify the V/As in the bottom ash. In this process, the solidification rate of V decreased but the solidification rate of As increased with the increasing of temperature. Both of V and As solidification rate decreased with the increasing of spent catalyst blending ratios. The leaching concentration and leaching rate of V and As in the bottom ash were lower than the emission standards. The leaching concentration of As and V of the bottom ash significantly decreased due to melting of bottom ash when the temperature reached to 1300 °C. When the blending ration of catalyst blending amount increased, the leaching concentration and leaching rate of V and As increased slightly due to the decreasing of the relative amount of CaO in bottom ash, which played an important roles in the solidification of V and As. [ABSTRACT FROM AUTHOR]