Elsevier

Journal of Cleaner Production

Volume 387, 10 February 2023, 135873
Journal of Cleaner Production

Hazardous industrial filter sludge immobilization with mayenite and gypsum

https://doi.org/10.1016/j.jclepro.2023.135873Get rights and content
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Highlights

  • Immobilization of a material rich with multiple heavy metals and sulphate.

  • Successful stabilization of most heavy metals with a mayenite based binder.

  • Ettringite as the main phase of the binder material.

  • Improved Se and SO4 immobilization via reducing gypsum.

Abstract

Heavy metals escaping from industrial processes and industrial waste are a significant environmental hazard all around the globe. Since they cannot be destroyed, the only way to manage the pollution is to capture and contain the hazardous components. This study focuses on stabilization-solidification of a highly toxic industrial filter slag that contains a range of different heavy metals in extremely high quantities. The stabilization-solidification treatment was executed with a mayenite and gypsum based solid cementitious binder. The major components that were monitored during the study were selenium, lead and sulphate. Different ratios of gypsum addition were tested in order to observe the effect of total sulphate content in the system to the immobilization efficiency of anionic selenium and sulphate. During the experiments, all cationic heavy metals were immobilized efficiently, most of them achieving the immobilization efficiencies of more than 99.9%. By adjusting the sulphate content of the system, the immobilization efficiency of selenium was improved from 95.669% to 99.925% and the immobilization efficiency of sulphate raised from 96.069% to above 99.964%. Controversially, the immobilization of lead was at its highest (99.999%) with high sulphate content and dropped to 98.162% as the sulphate rate decreased. The results show clearly that mayenite has good potential for stabilization-solidification applications.

Keywords

Heavy metals
Hazardous waste
Stabilization/solidification
Ettringite
Waste management
Leaching

Data availability

Data will be made available on request.

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