Probing microscale crystallization phenomena: Transforming waste slags into riches

Area of Science:

• Materials Science
• Geochemistry
• Environmental Science

Background:

• Waste slags from metal smelting and fuel combustion cause land occupation and pollution.
• Current methods focus on macroscopic crystallization, limiting precise microscale control for applications like carbon capture or glass ceramics.

Purpose of the Study:

• To investigate the microscale crystallization behaviors of blast furnace slag under varying isothermal temperatures.
• To establish correlations between microscale crystallization and temperature for optimized slag utilization.

Main Methods:

• Utilized the single hot thermocouple technique for visual analysis of crystal growth.
• Examined crystal growth modes, shapes, sizes, numbers, and translational rates at the crystal growth front.

Main Results:

• Identified five distinct crystal growth modes (equiaxed, equiaxed & columnar, columnar, columnar & planar, planar) with increasing isothermal temperature.
• Observed a significant increase in crystal growth front translational rate (0.011 to 43.7 μm·s⁻¹) with rising temperature.
• Documented a decrease in crystal number density (10⁴ to 10⁰ μm⁻²) as temperature increased.

Conclusions:

• Established clear correlations between microscale crystallization behaviors and isothermal temperature.
• Provided critical data for precise control of slag microstructures during thermal treatment.
• Advanced the potential for transforming waste slags into functional materials for carbon capture and glass ceramics.