Carbon sequestration behavior of magnesium oxychloride cement based on salt lakes magnesium residue and industrial solid waste

• The magnesium residue and phosphogypsum are utilized in carbon capture and storage technologies. • Phosphogypsum enhances the compressive strength and CO 2 sequestration capability of MOC. • Explained the impact of carbonation on the performance of MOC from a microscopic perspective. • The HMC phases precipitation process during the carbonation of MOC is elucidated. With the extensive utilization of lithium-ion battery in the electric vehicle and energy storage field, the consumption of lithium has been sharply increasing. Lithium resource occurrence area were facing increasing environmental pressure, particularly the magnesium residue (MR) produced in the lithium extraction process, and a sustainable exploitation pathway have not been established. In the framework of "net-zero", MRs were onverted to Salt lake magnesium oxide (SL-MgO) which was characterized by various elemental and surface analysis methods. Magnesium oxychloride cement (MOC) was prepared form SL-MgO and two industrial solid wastes [fly ash (FA) and phosphogypsum (PG)], and its carbon sequestration capacity was analyzed and evaluated. If all the MRs produced from the lithium extraction process were used to manufacture MOC materials for CO 2 sequestration. When the PG content was 20 %, the CO 2 sequestration capacity of the MOC was 0.29 kg/m 2 , the compressive strength was 85.30 MPa, and the MOC neutralized 220.10 % of the CO 2 emissions from the lithium extraction process. In this procedure, evidence was found of the typical metastable carbonate products identifiable. Overall, utilizing MRs and industrial solid waste to manufacture new low-carbon MOCs may become the most direct and effective countermeasures to alleviate environmental pressure in these regions.