The article presents the experimental research results of the flame propagation processes in the small vicinity of Bio-WCF particles during their ignition. According to the experimental researches, there have been obtained characteristic ignition delay times (t ign ) and times of full engulfment of the fuel particle in fire (t sf ). We have analyzed the influence of metamorphism degree of fuel basic component (coal) and sort of biomass on characteristics of these processes. It has been shown that increase in concentration of biomass in fuel leads to decrease in ignition delay times and fire propagation in boundary layer of the Bio-WCF particle. We have recognized that the oxidizer temperature (T g ) strongly influences the fire propagation dynamic in small volume vicinity of fuel particles. Also, we have observed that the effect of influence of oxidizer temperature (T g ) on the time of full engulfment of the fuel particle in fire (t sf ) differs from the predicted once. Increase in T g in a certain period of changes in its values (T g  = 1073-1273 K) leads to increase in time of full engulfment of the Bio-WCF particle in fire. The hypothesis describes the influence of ambient temperature on t sf was formulated. We have substantiated the hypothesis using the results of mathematical modeling. This hypothesis describes the physical mechanism of the influence of water vapors, which are formed during intrapore moisture evaporation on characteristics and conditions of volatile combustion in the boundary layer of the fuel particle.