Fundamentals of processes for redn. of carbonates and silicates to CO, K, Na, Si, SiO2 and FeO in blast furnace were presented. In particular, the cycle of alkaline carbonates and silicates and their influence on the blast furnace atmosphere, construction materials and produced pig Fe were analyzed. The unpublished balance data on blast furnace charge compn. and quality taken form the Czech industrial metallurgical practice were also included and discussed.