Blast furnace air tuyeres are one of the most important elements of the blast furnace design, determining the efficiency of its operation. Formation of "dead man" on the hearth bottom, or in other words, ore-coke sinter is considered as an unfavorable factor affecting the safety of large-volume blast furnaces. The main factors influencing the formation of "dead man" are violation of normal gas distribution and "cooling" of the blast furnace. This work is devoted to determination of the effluence procedure of the gas-coal flow using the Glinkov criterion. It is shown that a bubble effluent flow prevails in large-volume blast furnaces, i.e. a stable gas zone does not form in front of the tuyere tip. The bubble effluence mode of the gas-coal flow contributes to the growth of "dead man", which, as a result, can lead to an emergence situation. Prerequisites for burnout of the walls of the tuyeres are created in these conditions, while frequent terminations of the blast furnace operation to replace the tuyeres disorganize the melting technology. The maximal temperature in the tuyere zone has been calculated in this work. It exceeds the theoretical combustion temperature in the blast furnace hearth, what can adversely affect its operation, because the likelihood of an explosion of the blown natural gas will increase. The resulting heat flow on the tuyere tip was calculated in the work, taking into account the "dead man" formation. This flow exceeds the allowable one, what provokes a massive burnout of the tuyeres and the tuyere cooler.