Thermostrengthening modes in getting heat-strengthened pellets in weak oxidizing atmosphere with residual carbon for blast furnace melting

In the course of the laboratory tests, that are close to industrial modes of bowl pelletizers and roasting bowl operations, thermostrengthening modes of raw pellets have been worked out and selected, the main technological feature of the pellets being the presence of rolled up solid fuel. The results, obtained in the tests, showed that the selected modes make it possible to get heat-strengthened pellets with the maximum amount of residual carbon in the final product. The results, demonstrating the effect of the heating rate on the process parameters, in particular, on the content of residual carbon in the obtained heat-strengthened pellets are important. It has been shown that increasing the heating rate of raw pellets from 100 to 500°C/min, and cooling rate of the heat-strengthened pellets from 100 to 600°C/min with decreasing oxygen content in the heat-carrying agent for gas burning in the burners and cooling gas from 21% to 10,3-5,1% make it possible to increase the content of residual carbon in the heat-strengthened pellets from 0,8-1,9% to 3,5-3,7%. The obtained heat-strengthened pellets with the residual carbon not only satisfy all the requirements of the blast furnace melting, but also possess better metallurgical characteristics than oxidized heat-strengthened pellets