When siderite ores calcining in shaft furnaces gas there is a significant non-uniformity of temperature and velocity fields in all horizons of the layer. Heat exchange in the preheating zone are of low intensity with the formation of exhaust gases at temperature of about 230°C and displacement of their main mass towards the place of suction. The maximum temperature of the heat carrier is observed at its output from the fire place of the furnace. In the cooling zones the best conditions for reducing the temperature of the materials are created in the peripheral region, the most remote from the heat carrier. In the preheating zone of the furnace, the degree of completion of the heat treatment of siderites is not more than 78%, and compaction processes are limited to the individual pieces to the oxidation of the decomposition products of carbonates with the transfer of these processes to the cooling stage.The development of the phenomena of solid-phase sintering and materials melting is limited within the cooling zones in the degree of development of no more than 1-3%. The output of annealed siderite does not exceed 47.67%. Тhe roasting process of siderite occurs with a slight evolution of heat by oxidation of iron and manganese oxides. The thermal efficiency of the cooling zone 1 does not exceed 35% and the cooling zone 2 - 84,42%.