Solidification/stabilization of chromite ore processing residue using alkali-activated composite cementitious...

Area of Science:

• Environmental Science and Engineering
• Materials Science
• Waste Management

Background:

• Chromite Ore Processing Residue (COPR) poses significant environmental and health risks due to Cr(VI) leaching.
• Current methods for COPR management require effective stabilization to mitigate these risks.

Purpose of the Study:

• To investigate the solidification/stabilization (S/S) of COPR using alkali-activated blast furnace slag (BFS) and fly ash (FA) based cementitious materials.
• To evaluate the immobilization efficiency of this novel binder compared to ordinary Portland cement (OPC).
• To assess the potential reuse of the treated COPR as a construction material.

Main Methods:

• Optimizing the BFS and FA proportions for alkali-activated binder preparation.
• Incorporating COPR into BFS-FA binder and OPC-based materials.
• Utilizing X-ray diffraction (XRD), FTIR, and SEM-EDS for material characterization and immobilization analysis.

Main Results:

• The alkali-activated BFS-FA binder demonstrated superior COPR immobilization compared to OPC-based materials.
• Characterization confirmed effective immobilization of COPR within the alkali-activated matrix.
• The solidification mechanism involves a combination of reduction, ion exchange, precipitation, adsorption, and physical fixation.

Conclusions:

• Alkali-activated BFS-FA binders are highly effective for the S/S of COPR, significantly reducing Cr(VI) leaching.
• The treated COPR shows potential for reuse as a construction material, offering a sustainable waste management pathway.
• The study elucidates the complex solidification mechanisms involved in this advanced stabilization process.