Quantitative X-ray Diffraction (QXRD) analysis for revealing thermal transformations of red mud

Area of Science:

• Materials Science
• Environmental Science
• Geochemistry

Background:

• Red mud, a byproduct of alumina refining, poses a significant global environmental challenge.
• Developing economically viable methods for red mud utilization is crucial for sustainable waste management.
• Ceramic production offers a promising avenue for transforming red mud into a valuable resource.

Purpose of the Study:

• To investigate the phase composition and transformation behavior of Pingguo red mud (PRM) under various thermal treatment conditions.
• To identify novel phases formed during the heat treatment of PRM.
• To explore the potential for resource recovery, specifically iron and titanium, from PRM.

Main Methods:

• Thermal treatment of Pingguo red mud (PRM) at different sintering temperatures.
• X-ray diffraction (XRD) analysis to determine phase compositions.
• Microstructural analysis to understand phase formation and transformation.

Main Results:

• Observed phases included hematite, perovskite, andradite, cancrinite, kaolinite, diaspore, gibbsite, and calcite.
• No TiO2 (rutile or anatase) or quartz phases were detected, distinguishing PRM from other red muds.
• A novel silico-ferrite of calcium and aluminum (SFCA) phase was identified in samples treated above 1100°C.
• Iron was primarily found in hematite and andradite, while titanium concentrated in perovskite and andradite.
• Titanium enrichment in perovskite after 1200°C treatment suggests a recovery strategy.

Conclusions:

• The thermal treatment of PRM leads to complex phase transformations, including the formation of a new SFCA phase.
• PRM can be considered a potential raw material for the iron-making industry due to the identified SFCA phase.
• The study provides a quantitative summary of PRM phase transformations, offering insights for waste-to-resource applications.
• Titanium recovery from PRM is feasible, particularly from the perovskite phase after high-temperature treatment.