Abstract:
Ternium, the largest steel maker in Latin America, in Brazil since 2017 working on the production of semifinished, serving various market segments, such as automotive, oil and gas, machinery, tin plate, naval and energy industries. The free opening rate has a great impact on the safety of operators, as it reduces the exposure to risk when using oxygen lance for opening, on the quality and cost of the steel produced as well. If there is non-free opening, an oxygen burning lance is required to open the ladle, causing the exposure of the stream to the atmosphere with consequent oxidation of the steel. Therefore, the proper choice of the filler sand material of the nozzle and well block, combined with good operational practices, such as monitoring the presence of skull at the bottom of the ladle, excess slag, dirt in the valve and misalignment of the addition tube, are factors that guarantee a high level of free opening. Aiming at a higher free opening rate, the sand filling system from quartz-chromite was changed to quartz-chromite-zirconite, developed by Carboox Resende Indústria e Comércio de Refratários Ltda. This work shows the results achieved with this new material and optimized operating practices that made it possible to increase the average free opening rate from 98.93% in 2018 to 99,69% in 2021, reaching the best free opening rate in 10 years of plant operation