Pellets are one of the main types of iron-ore raw materials used in ferrous metallurgy. In Russia, the overall production of this iron-ore raw material is continuously growing. The analysis of pelletizing technologies over the last years has shown changes in requirements for product quality, process performance, heat and power parameters, environmental performance and production conditions of both fired and pre-reduced pellets. The article provides the analysis of technological and structural defects of conveyor-type induration machines. In order to remove these defects, we have developed an integrated technology for the production of fired pellets of various purposes. This technology made it possible to create an energy-efficient thermal system of the induration machine that has no counterparts in the world. This thermal system takes into account characteristics of the initial raw material. Its implementation at Mikhailovsky GOK in Russia provided a specific natural gas consumption within 8–9 nm3 /t of pellets and specific energy consumption less than 36 kW·h/t of pellets. These parameters were received by mathematical modelling and introduction of two-layer drying in the pellet induration process. The new induration technology has been implemented in Brazil and is now spreading at other plants in Russia.
Keywords: pellets, iron-ore concentrates, induration machines, thermal systems, two-layer charging, pellet drying