Papers by Keyword: Direct Reduction

Abstract: This study uses direct microwave heating to investigate the direct reduction process in carbon-iron ore composite briquettes under varying pressing forces. The composite briquettes, made from magnetite iron ore concentrate, anthracite coal, and bentonite as binder, were pressed at 1-ton, 2-ton, and 3-ton loads and then subjected to microwave irradiation. X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy were employed to analyze the phase composition and structural changes. The results show that the 1-ton briquettes exhibited predominantly metallic Fe with minor fayalite and FeO phases, whereas the 2-ton and 3-ton samples displayed increased fayalite formation. Notably, re-oxidation occurred in the 2-ton and 3-ton samples, as indicated by the presence of Fe₃O₄. The higher pressing forces caused reduced air permeability and lower CO diffusion efficiency, hindering the reduction process. These findings highlight the influence of compaction pressure on the reduction process and the potential of microwave heating as an energy-efficient alternative in ironmaking.

Abstract: Direct reduction is one of the methods used in nickel extraction from limonitic nickel laterite. Briquettes become an essential part of the direct reduction. This research examines the appropriate com-paction pressure of briquettes to achieve the optimum concentration, recovery of Ni and Fe, and selectivity factors also analyze the com-pounds formed. The briquettes were made at a pressure of 20 Kgf/cm², 30 Kgf/cm², 40 Kgf/cm², and 50 Kgf/cm². This study was performed out by mixing the prepared materials and then compact-ing them to form briquettes. Then, it was put into a crucible, and the coal-limestone bed mixture is added and put into the muffle fur-nace. Then, the direct reduction was started by heating at 700°C for 2 hours and continued at 1400°C for 6 hours. Next, it was continued with magnetic separation and weighing of the reduction products. The products were tested with SEM-EDX to determine the content. The products were tested with XRD to determine the compounds formed. The optimal results were obtained at variations of 30 Kgf/cm² with a Ni content of 5.00% and Recovery of 86.76%.

Abstract: The increasing demand for stainless steel and the scarcity of sulfide nickel ore affect the increase of laterite nickel ore processing. One of the processes that has been proven can be applied to process laterite nickel ore is direct reduction. In the direct reduction, the reduction atmosphere was adjusted by controlling the volume of CO and CO₂ from carbon source materials, such as coal, charcoal, and green cokes. This research aims to analyze the effect of reducing agents type on nickel limonitic nickel briquettes on Ni and Fe content and recovery of Ni and Fe. The direct reduction process was conducted at 1400°C for six hours. The EDX test was conducted to analyze the elemental composition of the product, especially for Ni and Fe content. On the other hand, the XRD can be applied to analyze the compound formed in the product Greencoke will produce the highest Ni content (15.23%). The highest Ni recovery (96%) was obtained by the addition of green coke reducing agent. On the other hand, the highest Fe recovery (18.8%) was obtained by the addition of coal reducing agent.

Abstract: The present study deals with impact of gangue amount (Al₂O₃, SiO₂) in iron ores on reduction of its pellets for production of sponge iron. Iron ore pellets were reduced isothermally with noncoking coal fines in the range of 1123 - 1273 K with a time interval of 15, 30,45,60,90 and 120 min. As the temperature rose from 1123 to 1223 K, the reducibility index of iron ore pellets increased and then decreased at temperature 1273 K. All iron ore pellets shows complete reduction at temperatures of 1173 and 1223 K within 120 minutes. The reduction results clearly show that the reducibility of the pellets depends on the initial mineralogy of the ore. It was also observed that the reducibility decreased as gangue content (Al₂O₃ + SiO₂) increases. The activation energy of the pellets decreased from 46.54 and 49.13 kJ/mol when the gangue content increased. The pellets were metallographically characterized before and after reduction to identify phase transformations. Examination of the SEM microphotographs revealed that Whisker shape of iron grains were formed during the reduction process and clear porous structure was observed.

Abstract: Indonesia has abundant resources or raw materials, especially the iron sand raw materials. But, the iron sand processing in Indonesia is still low. Even though, the steel demand in Indonesia is still high. So, the iron sand processing product as raw materials in steelmaking is the solution of it. In this research, the study was conducted by using the variation of briquette dimension of mixture of iron sand and iron ore in Direct Reduction process. The aim of this research is to study the effect of briquette dimension on Fe content and degree of metallization of the Direct Reduced Iron (DRI). First, the iron sand and iron ore were crushed and shieved until pass the 50 mesh standar size. Then, iron sand and iron ore were mixed and briquetted based on the variation of dimension. There are three variations of briquette dimension. Then, the briquettes was reduced at 1250°C for 12 hours. The reduced briquettes then were analyzed using XRD, XRF and degree metallization calculation. The result showed that the dimension of briquette affect the Fe content and the degree metallization of DRI. The dimension of briquette will affect the reductor gas flow in the crucible, so the rate and direction of reduction process of iron oxide will be affected too. The best briquette is Briquette B (7.9 cm for inside diameter, 15.1 cm for outer diameter and 19.5 cm for the height), with 75.02% for Fe total content and 66.52% for degree of metallization. This was due to The briquette B has the most evenly diffused dimension either vertically and horizontally.

Abstract: The direct reduction of metals from a complex oxide with low iron content by solid carbon and indirect reduction by CO gas were studied in a vertical laboratory resistance furnace at 1300 °C for an hour reduction time. The experimental results were described from the point of view of the electrochemical nature of the metal reduction process, that involves the interaction of ions and electrons in the oxide lattice. The technique was developed by using the two different software programs for the quantitative estimation of the areas, average size and number of the metal forming in a complex oxide with extensive fields of vision. The obtained results of the quantitative characteristics of the metal forming during solid-phase carbo-thermal reduction were presented. The processes of reduction by solid carbon and CO gas based on the areas occupied by metal particles were quantitatively compared. The experimental results and the prospects for further experimental work were assessed and outlined.

Abstract: Ironmaking processes take three main forms namely; blast furnace, direct reduction and direct smelting processes. Ironmaking is energy intensive sector as it requires huge amount of natural resources. It is also very important for the worldwide economy where it provides the backbone for construction, transportation and manufacturing. Many factors are strongly affecting the developing of ironmaking processes such as energy consumption, materials costs, and environment problems. These factors should be considered when discussing any new trend for developing ironmaking processes. The present work handles the current status and future of ironmaking processes. The technical and economic environment that motivates the development of these processes will be also clarified. The manuscript is designated to investigate theoretically and practically the possibility of using nanomaterials in ironmaking processes. Nano-sized iron oxides can be considered a promising source for deceasing energy consumption in iron and steel industry. The reduction of iron oxide is the most important processes in ironmaking and usually operated at relatively high temperatures. The nanopowder of iron oxide could be charged to a blast furnace together with the blast, much like the current pulverized coal injection technology. In that case, the reducibility of blast furnace burdens will be improved and consequently the energy consumption for reduction will be declined. Accordingly, minimizing the energy consumption will greatly influence the gross energy consumption of iron and steel production.

Abstract: In this paper the process of direct reduction of vanadium slag was adopted. The main factor was determined by uniform experimental design and single factor analysis, and then the optimum process condition was drawn by the test. The test results showed that the regression equation curve fitting of the experiment data was very significant, the main factors affecting the vanadium slag reduction (according to the primary and secondary order) was the content of anhydrous sodium carbonate, roasting temperature, roasting time and reduction of carbon content. The factors for the reduction of the optimum process conditions are the carbon coefficient 1.04, roasting temperature 1100°C, roasting reduction time 4h, 4% mass percent of anhydrous sodium carbonate and slag. Under the optimum conditions, the actual rate of weight loss and theory rate of weight were close to 0, the results could be reproduced, and the vanadium slag metallization rate was 75%~83%.

Abstract: Rapid reduction roasting of low grade manganese carbonate ore by coal and biomass fuels from Hunan, China was investigated. Magnetic separation behaviors and magnetic properties of raw manganese ore and roasted manganese ores were analyzed. After reduction by coal and biomass fuels, the manganese ores demonstrate a new Mn-Fe oxide phase, showing obvious mixed magnetic behaviors of ferromagnet and paramagnet, and the magnetic susceptibilities of roasting ores rapidly increase to almost two orders of magnitude in comparison of the raw ores. The results show that magnetizing roasting technology could enhanced the magnetic properties of the manganese ores about two orders of magnitude higher than raw manganese ore at low roasting temperature. Thereby, we deduce that the weak magnetic separation combined with high magnetic separation could be adequate for roasted manganese ore to satisfy the requirement of electrolytic manganese industry. Application of biomass in manganese ore roasting process is promising to the effective use of biomass and for decreasing the consumption of fossil fuels in the manganese industry.

Abstract: Quality molten metal needed to produce thin wall ductile iron (TWDI). Pig iron, as the major base material to produce quality molten metal, due to its high price, has been change with scraps. The use of scrap as major base material associates with more cleaning and chemical composition adjustment. The ITmk3 technology in iron making has successfully produced iron nugget. Iron nugget can be use to substitute pig iron due to its quality that is comparable to pig iron but lower in price. This research conducted to see the effects of carbon content in producing iron nugget. Limonite iron ores used in this research are part of laterite rocks taken from Sebuku Island in South Kalimantan, Indonesia. Variation made to weight of carbon mixed with laterite. Heating temperatures of direct reduction process are 700°C, 900°C, and 1000°C. The process times are 10, 20, and 30 minutes. XRF used in analysing Fe content in laterite and XRD is used in analysing result of direct reduction process. The result shows that increasing carbon content to certain condition will increase the rate of gasification process during direct reduction. The increase of gasification rate will result to higher Fe formation.