Modelamento estatístico do consumo de carvão vegetal dos altos-fornos da Vallourec Tubos do Brasil em função da produção de ferro-gusa e das cargas ferrosas

Abstract

Hot metal manufacturing process in charcoal blast furnaces, besides complex, represents the largest cost of an integrated plant due to the high prices of the raw materials. A great problem of this operation type is the low stability, which is due mainly to variations in the raw materials quality parameters, charcoal especially, being important to know well theirs characteristics and consequences for the operation. Vallourec Tubos do Brasil developed Six Sigma projects based in DMAIC methodology to reduce the variability of raw materials sampling process. In addition, it has been carrying out studies to reduce hot metal production cost, using historical data on raw materials consumption and hot metal production in the blast furnaces. Afterwards, these data are turned into information that can be used to evaluate production cost and achieve better planning and results for the company. These studies allowed the development of a statistical approach to predict charcoal consumption in blast furnaces based on Response Surface Models (RSM) and Linear Regression Models (LRM). The developed models in this work provide a high level of confidence and allow the company to act preemptively fostering innovative business and in the action plan to reduce hot metal production cost, to improve raw materials processing and other actions in order to provide the blast furnaces with raw materials at minimal cost. It is special particularity and represents a great step in Vallourec Tubos do Brasil blast furnaces operation which no longer uses standard ferrous load and started to operate with greater flexibility and variability concerning the types of ferrous load applied to achieve better economic results.