Study on Extraction Valuable Metal Elements by Co-Roasting Coal Gangue with Coal Gasification Coarse Slag

Area of Science:

• Materials Science
• Environmental Science
• Chemical Engineering

Background:

• Coal gangue (CG) and coal gasification coarse slag (CGCS) are industrial byproducts with both hazardous and resource potential.
• Effective methods are needed for the high-value utilization of these waste materials.

Purpose of the Study:

• To investigate the co-roasting and sulfuric acid leaching process for extracting aluminum (Al) and iron (Fe) from CG and CGCS.
• To understand the activation behavior and phase transformation mechanisms during co-roasting.

Main Methods:

• Co-roasting of CG and CGCS followed by H2SO4 leaching.
• Characterization using TG, XRD, FTIR, and XPS.
• Gibbs free energy calculations to analyze phase transformations.

Main Results:

• Optimized conditions (8:2 CG/CGCS ratio, 600°C, 1h co-roasting; 30% H2SO4, 90°C, 5h leaching) yielded 79.93% total iron (TFe) and 43.78% Al3+ leaching.
• Co-roasting converted kaolinite to metakaolinite, forming sillimanite and hercynite.
• Iron phases transformed sequentially through hematite, magnetite, wustite, ferrosilite, hercynite, and fayalite.

Conclusions:

• Co-roasting significantly activates Al and Fe in CG and CGCS for acid leaching.
• The study demonstrates a viable pathway for the high-value utilization of coal waste materials.
• Both the acid leachate and the residue hold potential for further applications.