Research progress on carbon dioxide mineralization sequestration technology by tailings

Carbon dioxide capture,utilization,and storage(CCUS)has become a focal point of research for scientists worldwide to address the global warming issue.Among these studies,utilizing mine tailings as CO_(2)mineralization materials has emerged as a new research approach in recent years.This study reviews the research progress of using mine tailings for CO_(2)mineralization and sequestration.The reaction mechanisms of CO_(2)mineralization using tailings have been introduced first.Notably,ultramafic tailings containing divalent cations,such as Ca^(2+),Mg^(2+),and Fe^(2+),can react with CO_(2)to produce carbonate precipitates.Furthermore,factors including the size of mineral particles,reaction temperature,and pressure will influence the mineralization reaction rate.The activation methods of tailings to accelerate mineral carbonation have been summarized.The activation of tailings for mineralization generally includes acid leaching,ammonium salt pH swing,and physical grinding.Newly developed methods,such as a combination of acid digestion and electrolysis of olivine,have also been introduced.Thereafter,the processes and technologies for CO_(2)sequestration through tailings mineralization have been analyzed.The in-situ and ex-situ mineral carbonation processes have been introduced.The last part explores the technical approaches of synergistic mineralization and storage of CO_(2)by cemented tailings backfill in underground mined-out areas,which is considered to be one of the key technological pathways for CCUS in the future.However,critical technical challenges must still be addressed for this process,including lowcost multiphase CO_(2)storage in backfill plants,synergistic transportation of backfill slurries and CO_(2),and in-situ injection processes of CO_(2)in mined-out stopes to produce suitable carbon curing environments.The research content of this article can provide valuable insights for studies on the mineralization and storage of CO_(2)using tailings.

Rheology and microstructure effects of waste spent coffee grounds in modifying asphalt binder

Herein the biowaste by-product spent coffee grounds(SCGs)from coffee industry were incorporated into asphalt binders for performance enhancement.From the analysis of Fourier transform infrared spectroscopy(FTIR),differential scanning calorimetry(DSC),dynamic shear rheometer(DSR),and Brookfield viscosity rheometer,it is confirmed that SCGs have potential prospects as bio-waste modifiers in the application of sustainable pavements.Results demonstrated that the modification process was mainly based on physical reinforcement.Compared with that of the neat asphalt,the shearing stress-resistant ability and high-temperature performance of the SCGs modified binders with the appropriate addition presented a bit of improvement;whereas the binders with 1%and 3%SCGs exhibited remarkably enhanced low-temperature stability.However,notable weaknesses of practical performance were shown for the binder with excessive content of SCGs,indicating the necessity of proportion selecting before application.