Tsybulya E. Improvement of technology of thermoantracite in rotating kilns and electrocalcinators for electrodes and lining of ferroalloy furnaces

The thesis focuses on improvement of the technology of thermoantracite production in rotary kiln furnaces (RKF) and electrocalcinators (EC) for the purpose of increasing of self-baked electrodes and carbon lining quality and its stability for ferroalloys furnaces. The peculiarities of thermoantracite processing in RKF and EC are analyzed. Temperature distribution irregularities on working surface of periklas-chromite lining have been mathematically modeled and experimentally validated in the RKF No. 4 of JSC "Ukrgrafit". The lining wear in RKF have been studied and electron microscopy analysis of the microstructure constituents of the refractory have been carried out. New lining type with higher wear resistance for RKF hot zones are developed and justified: periklas-chromite with 5% Cr2O3 at the ratio Cr/Fe > 3.4 and periklas-spinel with 17% Al2O3. The construction of the electrocalcinator (EC) IET-10-UHL4 with single-phase AC nominal power 1600 kW is analyzed. The lining made of mullite-corundum MKS-72 was studied and its local destruction mechanism was investigated. New lining material MKS-85 was suggested that allowed increasing refractory stability by 7.1% and productivity by 5.3%. The power distribution by EC height was determined and the express method of thermoantracite quality control was suggested using the value of electrical resistance of unloaded thermoantracite. A single-stage calcination technology was developed with inter-electrode distance 1500 mm, current 100 A and feed-through 840 kg/h, obtaining specific electric resistance less than 950 µOhm·m and less power consumption by 3.6% vs. conventional technology.