Investigation on cogasification and melting behavior of ash-rich biomass solid waste and Ca-rich petrochemical sludge pyrolysis residue in CO2 atmosphere

Abstract

The process of gasification coupled with melting is an effective technology that can realize the clean disposal of hazardous solid wastes. In this study, the gasification and melting characteristics of Chinese medicine residue (CMR) and pyrolysis residue of petrochemical sludge (PRPS) blends were investigated. The gasification residues obtained at different gasification temperatures and with variant blend ratios (mass ratio of CMR to PRPS) were evaluated. Results demonstrated that the melting degree of gasification residues was proportional to gasification temperature, presenting as four distinct morphologies: the CaO-rich powder-like (1100 °C), the gehlenite-rich black-gray hemispherical (1200 °C), virid amorphous crystal (1300 °C), and transparent vitrified SiO2 (1400 °C). Especially, as increasing the content of CMR, the gasification and melting characteristic was promoted, which were related to energy resource attributes of CMR and supply of low-melting eutectic constituent elements. In addition, when the gasification temperature was 1300 °C, the mineral composition of gasification residues gradually transformed from Ca–Si–Al compounds into amorphous matter as increasing CMR content. Moreover, while the blend ratio further attained to 3:1, gasification residues appeared as distributed globules and syngas productivity was enhanced to 0.99 L/g. The leachability of heavy metals inside the melting slags could meet the established criteria, indicating the harmless disposal of hazardous wastes.