Improving the early reactivity of activated coal gangue by vibratory ball mill- The influence of particle fineness and specific grinding energy toward geopolymerization

This study investigates the mechanical activation of coal gangue via vibratory ball milling for durations ranging from 1 to 120 minutes and its subsequent application as a geopolymer precursor. Coal gangue, a significant industrial byproduct, requires precise structural modification to overcome its inherent chemical inertness. The evolution of the mechanically activated coal gangue’s physical properties including particle size distribution (PSD), specific surface area (SSA), and surface morphology was systematically characterized using Laser Diffraction and Scanning Electron Microscopy (SEM).

The influence of specific grinding energy on chemical reactivity and the resulting geopolymerization process was further evaluated through Fourier-transform infrared spectroscopy (FT-IR) and uniaxial compressive strength. A quantitative correlation was established between the specific grinding energy and characteristics of the activated coal gangue, and the final mechanical performance of the resulting geopolymer binders.

The experimental results demonstrate that while initial grinding significantly enhances reactivity by increasing the specific surface area , prolonged grinding beyond an optimal kinetic limit induces undesirable particle agglomeration. This over-grinding phenomenon leads to a reduction in effective surface area, which negatively impacts the dissolution rate and subsequent geopolymer strength. These findings provide a critical quantitative basis for optimizing grinding conditions, balancing energy consumption against material performance. Ultimately, this research offers a pathway for the enhanced value-added utilization of coal gangue in the production of sustainable, low-carbon geopolymer materials