The primary purpose of the study is to obtain physical insight into the stability of an oxy-coal flame as a function of changing primary gas composition (CO2 and O-2). Flame stability was measured by Zhang et al. using optical measurements of the flame stand-off distance in a 40 kW pilot facility. Large Eddy Simulations (LESs) of the facility were performed using a multi-scale simulation tool and provide additional insight into the experimentally observed data. The importance of factors such as heterogeneous reactions, radiation or wall temperature can be better understood thanks to simulations. The effects of three parameters on the flame stand-off distance were studied. Simulation predictions were compared to experimental data using the data collaboration method. Overall, this study shows that high-fidelity LES simulations combined with experimental data can yield a deeper understanding of very complex coal flames, indicate where experimental uncertainties lie and be a valuable tool for design, retrofit and scale-up of oxy-coal burners. (C) 2013 The Combustion Institute. Published by Elsevier Inc. All rights reserved.