The Brazilian steel sector currently faces a severe depression, with an installed capacity of 48.9 million tons of crude steel (which will reach 51.9 million in the first quarter of 2016) and there was a decrease in production of 1.9 per cent in relation to production in 2014 (33.2 million tons in 2015). In 2015, it was registered a level of use of 67.89 per cent from industries compared to 85 per cent considered as an indicator of good performance by the National Bank of Economic and Social Development (BNDES), percentage which decreased as consequence of the fall in internal consumption equivalent to 21 per cent (24 million). The brazilian steel industry uses blast furnace as a technology for obtaining pig iron. Currently, the blast furnace continues being the reactor which is considered the best option among the several technologies for obtaining pig iron due to the high production rate, high thermal performance, stability and operational safety as well as longevity of equipments. However, various improvements are being researched, being one of them the operational control of the reactor which aims to maintain its stability in order to prevent possible failures and reduce the energy consumptions to keep them competitive productivity on the international market. This work presents a model is unwrapped with the objective to generate the surface of minimum consumption of reductant (carbon) for the blast furnace ironmaking process. In developing the model the equilibrium conditions of the reduction, the mass and energy balances and the equations of major operational parameters, were considered. Its application to the blast furnaces is exemplified for real operational conditions, which were databases duly extracted from an integrated steelworks. It was also possible, from cutting plans on these surfaces, to obtain binary diagrams of RC-DR type (Reductant Consumption-Direct Reduction), able to be generated on-line with the process. Among the results, one could identify, confirm and predict through analysis of those real case studies, important thermodynamic unfeasibility of the furnace, which allowed to provide greater operational safety to the process. The excellent results obtained applying this model to regular and abnormal blast furnace operational conditions, led to conclude that their objectives were fully succeeded.