Elsayed Abdelhady Mousa

Influence of nut coke on iron ore sinter reducibility under simulated blast furnace conditions

Abstract One of the most important factors to increase the economic efficiency of the blast furnace process is to reduced coke losses (undersieve product known as nut coke). In recent years there has been increased interest in mixing nut coke in the sinter layers. In order to clarify the influence of nut coke on sinter reducibility, sinter and sinter–nut coke mixtures were isothermally reduced with 30%CO–70%N2 at 1173–1523 K using a muffle furnace supported by an on-line gas analyser. Reflected light microscopy, scanning electron microscopy and X-ray technique were used to characterise the microstructure and the different phases developed in the original and reduced sinter. Sinter reduced without nut coke participation exhibited reduction retardation at elevated temperatures (>1373 K) while the presence of nut coke prevented such phenomena. The rate controlling mechanism of sinter and sinter–nut coke mixture was predicted from the correlation between apparent activation energy calculations, mathematical modelling derived from gas–solid reaction model and microstructure examination.

Isothermal reduction behaviour of MnO2 doped Fe2O3 compacts with H2 at 1073–1373 K

Abstract Pure Fe2O3 and Fe2O3 doped with 2, 4, and 6 mass% of MnO2 (>99%) compacts annealed at 1473 K for 6 h were isothermally reduced with H2 at 1073–1373 K. The O2 weight loss resulted from the reduction of compacts was continuously recorded as a function of time using thermogravimetric analysis (TGA). High pressure mercury porosimeter, optical and scanning electron microscopes, X-ray phase analysis and vibrating sample magnetometer were used to characterise both the annealed and reduced samples. In MnO2 containing samples, manganese ferrite (MnFe2O4) was identified. The rate of reduction of pure and doped compacts increased with temperature and decreased with the increase in MnO2 content. Unlike in pure compacts, the reduction of MnO2 containing samples was not completed and stopped at different extents depending on MnO2 (mass%). At initial reduction stages, the decrease in the rate was due to the presence of poorly reducible manganese ferrite (MnFe2O4) phase which was partially reduced to iron manganese oxide (FeO0.899, MnO0.101) at the final stages. The reduction mechanism was predicted from the correlation between the reduction kinetics and the structure of partially reduced samples at different temperatures. The reduction of pure and doped samples was controlled by a combined effect of interfacial chemical reaction and gaseous diffusion mechanism at their initial stages. At final stages, the interfacial chemical reaction was the rate controlling mechanism.

Recent Trends in Ironmaking Blast Furnace Technology to Mitigate CO2 Emissions : Top Charging Materials

The iron- and steelmaking is the largest energy consuming in the industrial sectors. The high energy consumption is associated with emission of CO2 and other pollutants. The most common ironmaking process used in the world is the blast furnace which contributes around 70 % of the world’s steel production. Recently, blast furnace has undergone tremendous modifications and improvements to reduce the energy consumption and CO2 emissions. The modifications are being focused on two main approaches: (1) development of top charging materials and (2) injections of auxiliary fuels through blast furnace tuyeres. The present chapter will discuss the recent modifications and development in the top charging burden and how it could participate in minimizing the energy consumption and CO2 emissions for more efficient and sustainable iron and steel industry. The injection of auxiliary fuels will be discussed in details in another chapter. The enhancement of burden material quality and its charging mode into the blast furnace has resulted in a smooth and efficient operation. Recently, the usage of nut coke in the modern blast furnace is accompanied by higher production and lower reducing agent rates. An efficient recycling of in-plant fines by its conversion into briquettes with proper mechanical strength is applied in some blast furnaces to exploit the iron- and carbon-rich residues. Nowadays, novel composite agglomerates consist of iron ores and alternative carbonaceous materials represent a new trend for low-carbon blast furnace with lower dependence on the conventional burden materials. The recent investigations demonstrated that the novel composites are able to reduce the thermal reserve zone temperature in the blast furnace and consequently enhance the carbon utilization through its higher reactivity compared to fossil fuels. The top charging of bio-reducers and hydrogen-rich materials into the blast furnace is one of interesting innovations to mitigate the CO2 emissions. Although some of previous approaches are recently applied in the modern blast furnace, others are still under intensive discussions to enhance its implementations.

Recent Trends in Ironmaking Blast Furnace Technology to Mitigate CO2 Emissions: Tuyeres Injection

Minimizing the coke consumption in the blast furnace is the key to achieve both ecological and economic aspects by reducing the CO2 emissions and the overall hot metal production cost. Complementary injection of cheaper auxiliary fuels and waste materials into the blast furnace via tuyeres has been greatly modified in the recent years to reduce the expensive coke consumption. Nowadays, most of the blast furnaces all over the world use pulverized coal at different injection rates. The greatest influence of coal injection on lowering the production cost and enhancement of hot metal production rate has led to further investigations on the injection of various other auxiliary materials including coke oven gas, converter gas, blast furnace dust, waste plastics, charcoal and torrefied biomass. In addition, trials on the injection of iron ore fines, low reduced iron and BOF slag have been recently studied. The injection rate of auxiliary materials into the blast furnace should be optimized to attain the minimum coke consumption and stable operation. The present chapter will discuss the influence of various materials injection on the blast furnace operation. The injection limit and changing of the blast furnace operating conditions, hot metal quality and coke consumption will be explained based on the experimental trials and mathematical modelling.