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Article Citation - WoS: 4Citation - Scopus: 5Reduction Behavior of Iron in the Red Mud(Technical Faculty, Bor-serbia, 2021) Eray, S.; Keskinkilic, E.; Topkaya, Y. A.; Geveci, A.Red mud or bauxite residue contains significant quantities of industrial metals such as Fe, Al, and Ti, as well as rare earth elements such as Sc, Ce, and La. The authors performed a laboratory-scale project dealing with stepwise recovery of valuable elements from two bauxite residues, namely Iranian red mud (IRM) and Turkish red mud (TRM). The first stage involved the recovery of iron which was present in large quantities in red mud. Two different methods were investigated for this purpose: 1) solid state reduction followed by wet magnetic separation and 2) smelting. In the scope of this paper, some results of pyrometallurgical part of this project are presented. According to solid-state reduction experiments, it was found that more excess coal was needed for IRM (35%) than for TRM (15%) to maximize iron reduction. Temperature had significant effect on the reduction process and metallization increased from about 70% to about 95% when the temperature was raised from 1000 to 1200 degrees C. Metallization degree was reported to be slightly higher for IRM (96.2%) than for TRM (94.1%). The results demonstrated that a high degree of iron metallization can be achieved regardless of the chemical and mineralogical composition of the bauxite residue sample.Article Citation - WoS: 2Citation - Scopus: 2Use of Colemanite in Ferronickel Smelting(Technical Faculty, Bor-serbia, 2019) Keskinkilic, E.; Pournaderi, S.; Geveci, A.; Topkaya, Y. A.Use of colemanite in metal-slag systems aims primarily to decrease the viscosity of slag and, therefore, achieve better metal-slag separation. Enhanced metal-slag separation is helpful to decrease the number of suspended metal/alloy droplets in slag, i.e. the physical losses. In the literature, successful use of colemanite was reported both in steelmaking and copper matte smelting processes. Ferronickel smelting slags contain nickel in the range of 0.1-0.2% and correspondingly, metal-slag distribution ratio values of nickel are reported even above 200. On the contrary, nickel recoveries are hard to exceed 95%. This can be mostly attributed to the physical losses of nickel due to very high slag volume in ferronickel smelters; for 1 ton of ferronickel, 10-15 tonnes of slag are generated regardless of the type of the laterite, which contains significant quantity of ,gangue components. The authors thought that use of colemanite could be a solution to decrease physical losses. Therefore, the use of colemanite in ferronickel smelting was investigated in the present work. Laboratory-scale smelting experiments were conducted using calcined and prereduced laterites in a vertical tube furnace under different gas atmospheres. The amount of colemanite added was in the range of 0 - 2.5% of the total charge. The experiments were also performed using ferronickel and slag samples obtained from a ferronickel smelter.Article Citation - WoS: 4Citation - Scopus: 5NEW TRENDS IN BASIC OXYGEN FURNACE DEPHOSPHORIZATION(Technical Faculty, Bor-serbia, 2020) Keskinkilic, E.Except for special grades of steel where it is used as an alloying element, phosphorus is regarded as an impurity that must be removed. Considering the conventional integrated iron and steelmaking, there are primarily two processes for phosphorus removal. The first is a hot metal dephosphorization (DeP) process that is applied to a blast furnace for hot metal before the steelmaking process. The second is the basic oxygen furnace steelmaking (BOS), a unique method primarily used for steelmaking, with the exception of stainless steels. Hot metal phosphorus content has a direct impact on BOS. An increase of phosphorus in hot metal is mainly related to the use of high P2O5 containing iron ores. In the current literature review, new trends of phosphorus removal in converter steelmaking are outlined. The double-slag practice was reported to be successful when hot metal P content was larger than 0.100%. It was indicated that the tapping temperature was critical for the production of low-phosphorus grades for which maximum allowable P content was 0.007% and that high tapping temperatures should be avoided. The tap-to-tap time for the double-slag process was slightly longer than the conventional converter steelmaking. It was further reported that the double-slag practice would be more economical than an establishment of a separate hot metal dephosphorization unit, if low-phosphorus grades did not have a significant share in the product mix of a steelmaking company. Endpoint phosphorus prediction was one of the important recent trends of converter steelmaking. A mixed injection of CO2-O-2 to a basic oxygen furnace was applied to enhance dephosphorization, and promising results were reported. Unfortunately, a successful process for recycling of BOS dephosphorization slag has not been reported yet.Article Liquid Processing of Silicon Steels Using the Converter-Ladle Furnace-Circulation Degasser Route(Southern African inst Mining Metallurgy, 2019) Keskinkilic, E.Electrical steels are used in motors, power generators, and transformers for electrical applications owing to their superior magnetic properties. These properties are attributed to the presence of a significant amount of silicon in the steel composition. Silicon steels are mainly grouped into two categories: grain-oriented (GO) and non-grain-oriented (NGO). The Si content of silicon steels is generally between about 0.50% and 6.5%. Therefore, silicon steels are further classified as low-, medium-, and high-Si steels. In this paper, liquid steel processing practices for certain silicon steel grades are outlined by considering a steelmaking company that integrates a basic oxygen furnace (BOF), a ladle furnace (LF), and an RH-type degassing unit (RH). Possible problems are identified, suggestions are discussed, and conclusions are drawn on the basis of real plant data.Article Citation - WoS: 1Citation - Scopus: 2Laboratory-Scale Smelting of Limonitic Laterite Ore From Central Anatolia(Southern African inst Mining Metallurgy, 2017) Pournaderi, S.; Keskinkilic, E.; Geveci, A.; Topkaya, Y. A.The feasibility of ferronickel production from a low-grade limonitic laterite ore was investigated. The ore was first calcined and then prereduced in the solid state. The reduced ore was then smelted to produce ferronickel. The effects of coal addition, smelting temperature, and retention time on the process were investigated. Chemical and physical losses in the slag were separately quantified. Coal addition was the main parameter that controlled the ferronickel grade and losses in the slag. The melting point of the slag was well below that of the ferronickel, which enhanced metal-slag separation and minimized physical losses in the slag. A microstructural study of an industrial slag revealed that Cr-rich particulates, which were suspended in the slag, were mainly responsible for the physical losses in the slag.
