Paulo Santos Assis

Optimisation of COREX process

Abstract Coal and energy consumption in the COREX process can be minimised from the balance between the required and generated reduction gas. Metallisation ratio is calculated at the balance, which corresponds to the effective calorific value of smelting coal. The proper metallisation ratio will be defined in this paper, after which it is demonstrated that an effective calorific value of smelting coal is needed to minimise the consumption of energy in the process. In addition, heat stability is also an important parameter when using coal instead of coke to insure a useful fixed bed in the melter gasifier. By considering the above points the energy consumption in the COREX process can be optimised.

Avaliação técnica de minérios de ferro para sinterização nas siderúrgicas e minerações brasileiras: uma análise crítica

This paper provides a critical analysis of the methodology used in Brazil for routine technical evaluation of iron ore fines used in the sintering process based uniquely on chemical and granulometric parameters. The mineralogical characterization of adherents, intermediates and nucleantes particles of sinter feed and the main attributes that should constitute its microstrutural identity have been highlighted. It should contribute a great deal to optimize the process parameters during the various stages of the sintering process as well as promote better intrinsic sinter quality. Based on these concepts, it is expected that in future years, significant criterias will be developed for technical analysis of iron ores fines used in agglomeration industry.

Modelos de previsão da qualidade metalúrgica do coque a partir da qualidade dos carvões individuais e do coque obtido no forno-piloto de coqueificação

Coke has a major significance in the final cost of products. Besides, its properties are closely connected with the performance of blast furnaces. Therefore, seeking a type of coke compatible with the needs of the high furnace and at the lowest price may become a very hard task if it does not have the necessary tools available to accomplish a correct selection of coals. The main goal of this dissertation is to develop models for the prediction for DI - Coke Mechanics Strength and CSR - Coke Strength after Reaction, through of statistics analyses of industrial data and coking in pilot scale. The model for the prediction for DI represent 75,8% of industrial data, amounting to a precision improvement of 8,07% in comparison with the present model. Therefore, the new model has proved adequate and may be used as a tool to help the purchase of coals.

Avanços na injeção de carvão pulverizado para a sua aplicação em altos-fornos

Some data about coal powder injection have been shown and one physical model, with high thermal gradient constructed at Escola de Minas-UFOP is described Using mixture of coal (3) and pre-heating of the coal some tests have been done, giving the conclusions below: pre heating of coal could be a good idea for improving the results obtained into the blast furnace, so mixture of more than two coals, not common practiced, could improve the combustion rate.

Characterization of Metallurgical Coke Produced with Coal Mixtures and Waste Tires

The use of scrap tires in the coal blends is an alternative to reduction of coke production costs as well as mitigates the impact caused by tire accumulation in the environment. Tests were carried out on a pilot scale, with coal blends and waste tire in 4 levels and 3 particle sizes, in order to assess the impact on the produced coke quality, especially on the Strength after Reaction with CO2 - CSR and Drum Index (DI150-15). In addition, it evaluated the mechanical resistance to compression, punctual chemical composition by Energy Dispersive Spectroscopy (EDS) analysis beyond the carbonaceous matrix-tire interface by SEM microscopy. The results from the coking tests showed that addition of up to 3% of the average ground tire (20-30mm) with steel mesh, raised either as CSR DI150-15, making feasible added also from a technical point of view.

A INFLUÊNCIA DA VIBRAÇÃO MECÂNICA DA CARGA DE CARVÃO NOS ÍNDICES CSR E CRI DO COQUE METALÚRGICO

Steelmaking companies must be always being looking for innovation and how to develop their production methods, because this is unquestionable very important to keep the company competitiveness on world’s market. This research is about an improvement of metallurgical coke production on coke ovens by coal charge mechanical vibration, on this way will be possible a bigger oven loading and an utilization of more poor coal blends, and, consequently, cheaper. The scientific research has happened on experimental scale on a 4,5 kg capacity coke oven, The mechanical vibration was produced by a mechanical immersion vibrator, the one commonly used for concrete compacting on civil construction. The coke produced increased by 21% of the CSR value and a 26% reduction of the CRI. The results obtained contradicts some results of the literature that report that the CSR and CRI are not influenced by loaded coal density, although these studies the densification technique used was stamp charging.

Pelletizing furnace refractory lining life cycle extension by applying thermography analysis and direct refractory injection

The induration furnace is one of the most important devices in the pellet production system. It is responsible for ensuring the quality of pellets produced, since a high level of thermal energy is necessary to reach the physical properties needed. Therefore, the refractory lining performance is important to guarantee the quality of pellets and to avoid thermal losses. Minor failures in the refractory lining may result in serious damage, if it not previously identified and repaired. This article was written to explain a preventive technique to identify and repair such minor issues with the refractory lining before escalation. The use of this technique in the proper frequency may result in furnace life cycle extension.

Study of the Abrasion Resistance of Fe-Cu-Nb and NEXT 100® Metallic Matrices for the Manufacture of Diamond Tools

The substitution of cobalt, present in the commercial binder metal matrix commonly used by the industry, was analyzed: 25,2%Fe-49,5%Cu-24,1%Co – NEXT 100® by the niobium element of the Fe-Cu-Co system, obtaining 4 metal matrices: 28,34%Fe–56,66%Cu–15%Nb; 25%Fe–50%Cu–25%Nb; 21,67%Fe–43,33%C–35%Nb; 18,34%Fe–36,66%Cu–45%Nb. This study aims to evaluate the behavior of metal matrices to better choose the type of matrix to be used in the manufacture of diamond tools. The metal powders were blended according to the compositions of each metal matrix and then hot pressed at 800o /35MPa / 3min, thus occurring the sintering. The sintered samples of each metal matrix were conducted to the Abrasion Resistance test in order to verify the wear, for the accumulated times of 2, 6, 12 and 20 minutes. In these metal matrices, density, porosity and Vickers hardness (HV5) tests were performed to better understand the wear suffered by the samples. Thus, the metal matrix 25% Fe-50%Cu-25%Nb presented, in the general context of the properties and from the abrasive point of view, satisfactory results capable of replacing the NEXT 100 matrix.

Energy consumption in smelting reduction (SR) processes

In contrast, conventional processes use coke and hematite/sinter in the blast furnace, in SR processes, other alternative fuels and iron ore sources, like charcoal and fine iron ores, can be used to produce sponge iron. The use of these alternative sources, by SR processes, can reduce environmental impacts and lower production costs. At first, the concepts of the theoretical gas utilization ratio, the smelting heat of the iron ore and the effective calorific value of coal were introduced. Then, the reason for gas utilization ratio and its performance in the shaft as a reducer in the smelting process are discussed and calculated. The relationship between coal consumption and iron ore reduction in the fluidized bed are also discussed. Finally, the influence of post-combustion on coal consumption in an iron bath furnace are calculated and discussed.

Efeito da temperatura na velocidade de redução do MnO pelo carbono dissolvido em ligas líqüidas Fe-C-Mn

The objective of this work was to investigate the effect of temperature on the velocity of MnO reduction by a carbon saturated liquid iron bath. The tests were performed in a laboratory apparatus specially designed to simulate smelting reduction reactions. The reactions were carried out respectively at 1500°C, 1550°C and 1600°C, and also the initial manganese concentration in the bath were 0%, 10% e 40%. The apparent activation energies were graphically determined for the overall reduction process through the initial velocity method. The overall reaction rate increases as the temperature increases, and the apparent activation energies were 64,8, 63,13 and 63,25 kcal/mol, respectively for 0%, 10% and 40% of initial manganese content in the carbon saturated iron bath.