Lurgi gasification wastewater is a complex industrial effluent, and its direct discharge may cause water pollution and ecological damage. Conventional treatment methods are often technically challenging and costly, highlighting the need for simple and cost-effective approaches to wastewater resource utilization. Coal–water slurry (CWS), an alternative fuel characterized by high combustion efficiency and relatively low pollutant emissions, exhibits good adaptability to different slurry preparation waters. In this study, simulated Lurgi gasification wastewater was used as the slurry preparation water, and low-rank coal was employed to prepare CWS. The effects of the major wastewater constituents on coal surface properties and slurry preparation performance were investigated. Contact angle measurements showed that phenol improved the wetting characteristics of coal particles and increased the slurry concentration achievable at a specified viscosity. Phenol also reduced slurry viscosity without changing the slurry type, thereby favoring CWS preparation. Zeta potential measurements indicated that both aqueous ammonia and aniline increased the measured Zeta potential, suggesting an improvement in slurry dispersion stability. However, rheological measurements revealed that both constituents increased slurry viscosity, exerting an adverse effect on slurry preparation performance. Finally, the slurry properties obtained using deionized water, simulated Lurgi gasification wastewater, and simulated wastewater containing a combination of the three major constituents were compared to evaluate the individual and combined effects of these constituents on CWS preparation. The results provide a basis for the resource utilization of Lurgi gasification wastewater and the preparation of CWS from low-rank coal.

Lurgi gasification wastewater; coal–water slurry; low-rank coal; wettability; Zeta potential; rheological properties; wastewater resource utilization