An all solid waste CO2 sequestration material consist of multiple calcium silicate clinkers by carbide slag, copper tailing and red mud: Clinker crystal transformation and carbonation hardening properties

Abstract

In this study, a CO₂ sequestration material was obtained by all components solid wastes, i.e., carbide slag and copper tailing based on red mud (RM) as crystal regulator after a sintering and carbonation process. With the increasing dosage of RM, the mineral compositions of generated RM-modified clinkers were mainly γ-C₂S (i.e., around 80 %) at low dosage RM (i.e., 3.0 %), and was gradually increased content of β-C₂S (β-dicalcium silicate), C₃S (tricalcium silicate) and C₂AS (gehlenite) at high dosage RM (i.e., from 3.0 % to 10.0 %). Moreover, the compressive strength of various carbonated compacts made by RM-modified clinkers after CO₂ curing were shows firstly increased and then decreased with a RM dosage inflection of 5.0 %. This compressive strength results should be attributed to their carbonation activity, i.e., higher carbonation activity, higher compressive strength. The obvious carbonation activity difference of various RM-modified clinkers were not simply depends on their only γ-C₂S content, only β-C₂S content, only C₃S content or the sum of calcium silicate minerals, but more closely relate to their combined effect. This work provides a new utilization strategy of RM as crystal regulator according to its high alkaline and high Fe content composition characteristic for obtaining a CO₂ sequestration materials. And also laid a new insight for a synergistic CO₂ sequestration by multiple calcium silicate clinkers in the future.