Yavuz Topkaya

Sulfuric acid leaching of Turkish chromite concentrate

In this work a high grade chromite concentrate obtained from Pinarbasi–Kayseri district of Turkey was reacted with a solution of sulfuric acid and perchloric acid. The effect of sulfuric acid concentration, temperature, duration, and perchloric acid addition on leach recovery was studied. At the end of leach reaction chromium appeared in the solution as Cr3+ and it did not change to environmentally hazardous Cr6+. The final product in the solution was chromium(III) sulfate obtained with about 83% maximum recovery, under the optimum leaching conditions of 175 °C, 2 h, 70% H2SO4 and 1/2 perchloric acid/chromite ratio.

Dechlorination of a zinc dross

Abstract The possibility of decreasing chlorine content of a zinc dross containing 1.40% chlorine by washing with distilled water and sodium carbonate was investigated in this study. The dross sample was obtained from CINKUR which is the only primary zinc producer in Turkey. Temperature, time and solid–liquid ratio were the investigated variables in distilled water washing experiments. In addition to these variables, the effect of sodium carbonate amount was also studied in sodium carbonate washing experiments. The results showed that there was no advantage of using sodium carbonate in chlorine removal. Washing the zinc dross simply with distilled water at 95°C for a short period of time such as half an hour and at a suitable solid–liquid ratio between 1:2–1:10 removed about 80% chlorine found in the dross. Chlorine content decreased from 1.40% to about 0.20–0.30% in the dross.

Leaching by ferric sulphate of raw and concentrated copper-zinc complex sulphide ores

Abstract A composite mixture of three typical Cu/Zn complex ores, namely black-, yellow- and altered-ore, from Cayeli deposit in Turkey, was used for leaching experiments under atmospheric pressure in ferric sulphate solutions, in order to study the reaction kinetics of the copper and zinc dissolution in the temperature range from 50 to 80°C; also in the presence of a solvent for elemental sulphur, such as CCl 4 . Owing to the fact that quite low copper extraction yields were obtained and to the clearly evident necessity of using pressure leaching in autoclave at higher temperatures, a tentative process of the ore enrichment by selective or bulk-flotation was then examined. Leaching tests in an autoclave at temperatures ranging from 100 to 230°C were carried out on the bulk-concentrate produced. Good extraction yields for both metals were achieved at 140°C after a few hours leaching by ferric sulphate.

Investigation of effect of colemanite addition on copper losses in matte smelting slag

Abstract In this study, the aim was to reduce copper losses to slag in copper production by using a boron compound, called colemanite (2CaO.3B2O3.5H2O), as flux, besides silica. In order to achieve this purpose, two different matte–slag couples were used; the flash furnace matte-slag obtained from Eti Copper Inc. (EBİ) and a master matte–slag without copper produced synthetically under laboratory conditions. Chemical analyses of flash furnace slag and synthetic master slag were 0·88%Cu–36·1%SiO2–43·9%FeO–3·7%Fe2O3 and 37·6%SiO2–60·0%FeO–2·4%Fe2O3 respectively. In each experiment, the same amounts of slag and matte were mixed with the addition of predefined amounts of colemanite and melted together at 1250°C for different durations under nitrogen atmosphere in a silica crucible. Results showed that it was possible to decrease the copper losses to about 0·3–0·4% by accelerating the settling rate of matte particles by the addition of colemanite, which was attained by the expected increase in flash furnace slag fluidity and lowering of its liquidus temperature. Dans cette étude, le but était de réduire les pertes de cuivre dans la scorie lors de la production de cuivre en utilisant un composé de bore, appelé colémanite (2CaO.3B2O3.5H2O), comme flux, en plus de la silice. Afin d’atteindre cet objectif, on a utilisé deux couples différents de matte-scorie; la matte-scorie du four éclair obtenu de Eti Copper Inc. (EBİ) et une matte-scorie modèle sans cuivre, produite synthétiquement sous conditions de laboratoire. Les analyses chimiques de la scorie du four éclair et de la scorie synthétique modèle étaient de 0·88%Cu–36·1%SiO2–43·9%FeO–3·7%Fe2O3 et de 37·6%SiO2–60·0%FeO–2·4%Fe2O3, respectivement. Dans chaque expérience, on a mélangé la même quantité de scorie et de matte, avec addition de quantités prédéfinies de colémanite, et fondu ensemble à 1250°C à différentes durées sous atmosphère d’azote dans un creuset de silice. Les résultats ont montré qu’il était possible de diminuer les pertes de cuivre à environ 0·3–0·4% en accélérant la vitesse de sédimentation des particules de matte par l’addition de colémanite, ce qui était atteint par l’augmentation attendue de la fluidité de la scorie du four éclair et par l’abaissement de sa température de liquidus.

Desulphurization Characteristics of Ladle Furnace Slags of a Low Sulphur Steel

Abstract In steelmaking, one of the most important parameters for desulphurization is the oxygen potential of the system which can be expressed either by oxygen activity of the steel or by Fe t O activity of the slag. Removal of sulphur from the steel is enhanced when FetO activity of the slag and thus oxygen activity of the steel decreases. In this paper, ladle furnace slags of a low S steel quality currently produced in Eregli Iron and Steel Works Company (ERDEMIR), Turkey, were studied. Activity coefficients of Fe t O, γ Fe t O were calculated with the relation obtained from the literature. The relation between %Decrease α Fe t O and %DeS (measured) was studied. The percentage of sulphur removal was also investigated using the data of the oxygen activity of liquid steel.

Mechanochemical and combustion synthesis of CeB6

Abstract CeB6 powder was prepared via combustion synthesis (CS) and mechanochemical processing (MCP) methods starting from CeO2, B2O3 and Mg powder mixtures. In CS, reactant mixtures were ignited in a preheated pot furnace under argon atmosphere. Products contained CeB6, MgO and Mg3B2O6, as revealed by X-ray diffraction analysis. After leaching in 1 M HCl for 15 h, MgO was removed but Mg3B2O6 could not be removed from the products. Ball milling of products in ethanol prior to leaching made the removal of Mg3B2O6 possible by leaching. Yield of CeB6 was 68.6 % in CS. MCP was performed in a stainless steel vial with a planetary ball mill at 300 rpm for 30 h. MCP products contained CeB6, MgO and small amount of Fe. Leaching in 1 M HCl for 30 min was sufficient to remove MgO. Yield of CeB6 was 84.4 % in MCP. According to scanning electron microscopy examinations, particles of CeB6 prepared by CS and MCP had submicrometer size. Average particle sizes were determined as 290 nm and 240 nm, respectively.

Extraction of cobalt and copper from Küre pyrite concentrate

Abstract Three methods were investigated for the extraction of cobalt, copper and gold from Kure pyrite concentrate. These were chloridizing roasting, chloridizing volatilization and sulphating roasting processes. For chloridizing roasting, the pyrite concentrate was dead roasted first to adjust sulfur content to about 4%. Then, the pyrite cinder obtained was mixed with NaCl and pyrite concentrate, and roasted to produce soluble chlorides of copper and cobalt. For chloridizing volatilization, copper, cobalt and gold in the pyrite cinder, which contained 0.12% sulfur, were tried to be volatilized as chlorides with the addition of CaCl2. In sulfating roasting, cobalt and copper were tried to be extracted by converting them to their water soluble sulfates. Three different procedures were applied. In the first one, sulfating roasting was done in a closed vessel. In the others, a muffle furnace was used. In the closed vessel experiments and also in one set of experiments in the muffle furnace, the pyrite concentrate was sulfated directly by adjusting the roasting temperature and time. However, in the last set of experiments, Kure pyrite cinder was sulfated by pyrite concentrate addition and roasting in a muffle furnace. In the end, the maximum recoveries were obtained by chloridizing roasting. Although sulfating roasting gave lower recoveries, it was more economical.

Extraction of Scandium from Lateritic Nickel-Cobalt Ore Leach Solution by Ion Exchange: A Special Study and Literature Review on Previous Works

Scandium, as the lightest rare earth element in the periodic table, has critical utilization areas such as the aerospace industry, solid oxide fuel cells, electronics industry and is also used in metallurgical applications. Due to the scarcity of high grade scandium deposits and high processing costs, scandium production rate is limited. It is generally produced as a co-product of primary metal processes, wastes and reprocessed tailings. Processing operations for scandium containing ores include leaching, solution purification, ion exchange chromatography, solvent extraction, and precipitation. Although previous studies were more focused on solvent extraction, ion exchange applications have also emerged as an alternative pathway. At the present time, the extraction of scandium from titanium, tungsten, uranium residues, red mud and phosphogypsum by IX have been made. The objective of this study is determining the extraction possibility of scandium from the leach solution of lateritic nickel-cobalt ore by ion exchange chromatography using various resins.

Volume combustion and mechanochemical syntheses of LaB 6

LaB6 powder was produced by volume combustion synthesis (VCS) and mechanochemical synthesis (MCS) methods, through magnesiothermic reduction of La2O3 and B2O3 powders. VCS was achieved by rapid heating of the reactant mixture in argon, whereas MCS was performed via high energy ball milling. All the products were subjected to XRD, SEM, gravimetric and particle size distribution analyses. MCS resulted in the expected products LaB6 and MgO. In addition to these, VCS products contained LaBO3 and Mg3B2O6. In order to obtain pure LaB6, 30 min leach in 1 M HCl was found to be enough for MCS products, whereas Mg3B2O6 could not be removed from the VCS products even after 15 h leach. Wet milling of VCS products before leach facilitated obtaining of pure LaB6. Average particle sizes of the LaB6 powder produced by VCS and MCS were 290 and 180 nm, respectively.

A Study on the Characterization of Nickel Laterites of Central Anatolia

There are mainly three commercial nickel laterites in Turkey: Gordes, Caldag and Sivrihisar. The first two appear in Western Anatolia. The third one, Sivrihisar (Yunusemre) laterites have been found in the first decade of the millennium, in the Central Anatolia region of Turkey. Since then, mining facilities have been continued in Yunusemre. Calcination, prereduction and smelting of Sivrihisar laterites have been extensively studied and published. In the current work, some results of the studies related to characterization of Sivrihisar laterites will be presented.