Search

The current study presents a novel approach for the utilization of ultra-fines iron ore (−0.2 mm) in sintering process through its conversion into mini-pellets (4–9 mm). The mini-pellets were composed of ultra-fine iron ore and calcium hydrate while coke fines were used as a coating layer. One part of mini-pellets was cured with CO2 to improve the strength of green pellets while another part was kept uncured. The trails were carried out in sinter pot after adjusting the operating parameters. The utilization of 30% cured mini-pellets was accompanied by the constant highest temperature (≈1400 °C) in combustion zone. On the contrary, the sinter prepared using 30% uncured mini-pellets showed the highest temperature (≈1471 °C) at the beginning of sintering process followed by a gradual decreasing in the temperature. The permeability of sinter bed was improved by using cured mini-pellets in the sinter mixture. The sinter indices including the product yield, tumbler index and fuel consumption are measured. Reflected light microscopy, scanning electron microscopy, and X-ray diffraction analysis were used to characterize the microstructure and the developed phases.

One way to decrease the reducing agent rate in a blast furnace (BF) is the lowering of thermal reserve zone (TRZ) temperature by using self-reducing pellets (SRP). The lower strength requirement of raw materials for small BFs allows the charging of SRP. In the scope of the current study, the behavior of SRP under the TRZ simulated conditions has been investigated. Coal, charcoal, and coke breeze were used as embedded reducing agents. The reduction experiments have been performed under different iso- and non-isothermal scenarios. A Tammann furnace laboratory rig and a simultaneous Thermogravimetric/Differential Thermal Analysis (TG/DTA) experimental set were used for investigations. Mass loss, reduction degree, metallization degree, volume change, and reaction heat flow were examined. The results from experiments with TRZ condition show that embedded reducing agents, especially charcoal, promote iron oxide reduction in pellets. The crushing strengths of SRPs after both methods of hardening, fire-hardening and cement-bonded curing, and the reduction of cement-bonded SRP after curing have been investigated as well.

Recently a special attention is being paid on the combination of different ironmaking technologies in the integrated steel plant to maximize the efficiency of the overall process. The utilization of coke oven gas for production of direct reduced iron (DRI) in the integrated steelmaking route is still under evaluation and discussion. In this study, iron ore pellets were isothermally reduced with simulated original and reformed coke oven gas (RCOG) at 700–980°C. The results were compared with those obtained by the reduction of pellets with the original and reformed natural gas (RNG). The highest reduction degree was obtained for the pellets reduced with RCOG while the lowest reduction degree was exhibited by original natural gas. On the other hand the rate of reduction with original coke oven gas was sharply increased at temperature of about 900°C to become higher than that of RNG. A slow down phenomenon appeared at the later stage of reduction due to the intensive carbon deposition. The soot formation increased as CH4 content and/or the temperature of reducing gas increased. Reflected light microscope, scanning electron microscope with EDX, and high performance X-ray diffraction analysis were used to estimate the reduction kinetics and mechanism.

In recent years an intensive work has been carried out to decrease the coke losses of the blast furnace through mixing small-sized coke called ‘‘nut coke’’ in the iron ore burden layers. In order to clarify the influence of nut coke on the pellets reducibility, industrial iron ore pellets were reduced with and without nut coke participation under different temperatures and atmospheres. Isothermal and non-isothermal reduction tests under simulating blast furnace conditions were performed using an experimental laboratory rig. Furthermore, reflected light microscopy, scanning electron microscopy and X-ray technique were applied to characterize the microstructure and different phases developed in the origin and reduced pellets. Pellets reduced isothermally without nut coke participation exhibited reduction retardation (RR) at elevated temperature (� 1373 K) whereas the presence of nut coke had a positive effect of preventing such phenomena. The non-isothermal reduction of pellets showed that, as the amount of nut coke in pellets bed increased, the reducibility of pellets increased, too. The rate controlling mechanism of pellets and pellets-nut coke mixtures was predicted from the correlation between apparent activation energy calculations and microstructure examination.

For about 10 years the steel industry in Brazil has been using pulverized coal injection (PCI) technology in blast furnaces based on imported coals. In order to decrease the dependence on imported coals, Brazilian coal which has limited use due to high ash content is suggested to be mixed with imported coal and charcoal. The aim of this study is to examine the reactivity and combustion behaviour of the mentioned materials. The use of charcoal in the Brazilian steel industry reduces the CO2 emissions, since it represents a renewable source of carbon. The reactivity of the coal, charcoal and mixtures is evaluated through TGA. To provide a useful insight into the practice of PCI in blast furnaces, experiments are carried out with a laboratory rig at RWTH Aachen University that simulates the behaviour of fines injected into the raceway. The results of this study are presented and discussed.

This contribution deals with advanced educational technologies needed to equip customers from higher education institutions, research and industry with efficient tools supporting their work and operating new skills-training methods. The challenges are reducing the training costs, improving quality and increasing the number of graduates in engineering departments. The concept of a Virtual Lab based on the combination of various teaching methods and tools is presented. Principles of mathematisation in metallurgical education and training are discussed. An example of online course designed in the form of Virtual Lab is demonstrated.