Performance of water-based foams affected by chemical inhibitors to retard spontaneous combustion of coal

The micelle generating process of the sodium dodecyl sulfate (SDS) solution with the addition of chemical inhibitors was elucidated using phase separation model, and the descending order of the capacity for the selected chemical inhibitors to reduce the critical micelle concentrations of the solution are MgCl2, CaCl2, NH4HCO3 and NH4Cl. The data to quantitatively describe the foam decay process, including foaming ratio, foam life and decay behaviors, was obtained by pressure measuring system. The results indicate that chemical inhibitors can improve the solution foamability. The capacity of the inhibitors to enhance the solution foamability is sorted as NH4Cl, NH4HCO3, MgCl2 and CaCl2 which can distinctly improve the foam stability as well. The capacity of the inhibitors to enhance the SDS foam stability can be arranged as MgCl2, NH4Cl, NH4HCO3 and CaCl2. It is observed that the gravity drainage plays a leading role in the increase of proportion of diffusion drainage. The oxidation dynamic parameters of the coal samples treated by inhibition foams were investigated using thermal analysis technique, and their synergistic effects on inhibiting coal oxidation were explored.