Comprehensive Benefit Evaluation of Utilisation and Disposal Technologies of Coal Chemical Waste Salts Based on the DANP-Cloud Model Framework

Coal chemical waste salt is a by-product of zero-liquid-discharge wastewater treatment in the coal chemical industry. Owing to its high salinity, complex impurity profile, and substantial compositional variability, its disposal and resource recovery remain highly challenging. This study investigated representative coal chemical waste salt samples from the Ningdong Energy and Chemical Industry Base and characterized their physicochemical properties and pollution profiles through compositional tracing, characteristic pollutant analysis, and laboratory testing. To identify suitable treatment pathways, a multidimensional integrated benefit evaluation system combining the DEMATEL (Decision-Making Trial and Evaluation Laboratory) -based ANP (Analytic Network Process) and a cloud model was developed to assess six waste-salt utilization and disposal technologies. The comprehensive benefit ranking was as follows: pyrolysis plus impurity removal and salt separation > ion-exchange membrane caustic soda production > impurity removal and salt separation > short-path sodium sulfate-to-ammonium production > MVR (Mechanical Vapor Recompression) plus rigid landfill > evaporation ponds plus flexible landfill. The results indicate that salt-separation technologies show superior overall applicability, whereas ion-exchange membrane caustic soda production provides the greatest environmental benefits. However, most resource recovery technologies remain constrained by limited product profitability and marketability. The proposed methodology provides decision support for high-value utilization of coal chemical waste salt in the Ningdong Industrial Base and may also serve as a reference for benefit evaluation in other engineering projects.