Micro fly-ash particles stabilized Pickering foams and its combustion-retardant characteristics

We have developed a new class of aqueous Pickering foams, which were stabilized by sodium dodecyl sulfate (SDS)-modified micro fly ash (FA) particles and exhibited excellent stability and inhibition characteristics for coal spontaneous combustion. Specifically, this study aimed to characterize the microstructure, foaming behavior, evolution process and inhibition characteristic for coal spontaneous combustion of these Pickering foams. The evolution of these Pickering foams is quantified by measuring the rate of bubble growth as well as the kinetics of liquid drainage and the two processes are correlated. These data allow us to identify a transition time, separating two distinct stages of foam evolution. An increasing FA concentration in the Pickering foams lead to an increase in foam stability, which arises from the formation of a robust FA-armoured bubble structure. In addition, the coal acceleration oxidation experimental results show that these Pickering foams can improve the coal thermal stability and effectively inhibit the coal oxidation process by increasing crossing point temperature (CPT) and reducing CO emission. The results indicate that the prepared aqueous, low-cost and nontoxic FA-stabilized Pickering foams effectively slow the oxidation of coal, thereby demonstrating its application potentials in coal spontaneous combustion prevention and control.