Abstract: Solid wastes generated during industrialization often contain high concentrations of heavy metal ions, and the potential release of these heavy metals requires urgent attention. Conventional heavy metal ion suppression techniques are difficult to balance both cost and efficiency issues, whereas the CO₂ mineralized lightweight aggregate used in this study to adsorb and solidify heavy metal ions (small particle size of the lightweight aggregate, homogeneity throughout the reaction process, and comparative sampling) is an effective and economical way of treating heavy metal-containing wastes. The results showed that, after the light aggregate experienced CO₂ mineralization, the precipitation of copper element decreased from 0.1518 mg/L in the natural condition to 0.0023 mg/L in the 120 min mineralization condition, which was about 1.43% of the original; the precipitation of lead element decreased from 0.382 mg/L in the natural condition to 0.0159 mg/L in the 60-min mineralization condition, which was about 4% of the natural condition. Chromium increased from 0.1079 mg/L without mineralization to 0.4278 mg/L after 120 min of mineralization, and the increase of physical adsorption and chemical precipitation by mineralization improved the overall fixation efficiency of Cu and Pb, but the fixation of Cr was adversely affected by the effect of Ca²⁺. Overall, this study is of great significance for reducing environmental pollution and improving the environmental friendliness of the materials, which provides a new technical path for the application of coal-fired solid waste-based materials in the field of environmental remediation.