Cüneyt Arslan | Istanbul Technical University (original) (raw)
Papers by Cüneyt Arslan
Journal of Electronic Materials, 2005
In this study, the effects of current density and bath temperature on the hardness, thickness, an... more In this study, the effects of current density and bath temperature on the hardness, thickness, and morphology of boride layer are systematically investigated. The electrochemical boride coating on steel substrates is carried out at various current densities (50-700 mA/cm 2) and bath temperatures (800-1000°C) at constant electrolyte composition and electrolysis time. The FeB, Fe 2 B, and Fe 3 B phases are detected by the x-ray diffraction method. The hardness of the boride layer reaches approximately 1800 HV on the surface and gradually decreases toward the matrix. The optimum current density and electrolyte temperature for the boriding of low-alloy steel are determined as 200 mA/cm 2 and 900°C, respectively.
Hydrometallurgy, 1999
The aim of this study is to investigate the utility of adding chelating agent during hydrochloric... more The aim of this study is to investigate the utility of adding chelating agent during hydrochloric acid leaching of low-grade scheelite concentrates, obtained from Uluda , Bursa (Türkiye). Examined parameters were as follows; leaching conditions, selective precipitation of tungsten salt ...
Scandinavian Journal of Metallurgy, 2002
Scheelite concentrates, obtained from Uludag, Bursa (Türkiye), containing roughly 50% W, are trea... more Scheelite concentrates, obtained from Uludag, Bursa (Türkiye), containing roughly 50% W, are treated by the chelate-added acidic leaching route. Dissolved tungsten ions are then selectively precipitated by the addition of "ammonia ion containing" reagents-either organic or inorganic, and thus are purified from other ions present in the solution. The optimum precipitation conditions are investigated with the aim of producing pure tungsten oxide via thermal breakdown process. Weight loss ratios of the samples vary between 8.7 and 9.6% at the end of two-hour thermal breakdown process. This amount validates the formula suggested for the complex salt; (NH 4) 3 PW 12 O 40 •9H 2 O. Tungsten trioxide obtained, on the other hand, can be suitably employed in tungsten-related powder metallurgy applications with its extremely low impurity content of 0.04% Mo, 0.15% SiO 2 , 0.06% Fe and 0.03% Al.
Developments in Mineral Processing, 2000
Slags formed during brass smelting contain a significant amount of metallic value. The glassy and... more Slags formed during brass smelting contain a significant amount of metallic value. The glassy and oxidized portion of the ground slag, usually referred to as "brass ash", consists of compounds such as ZnO, ZnO-SiO2, Cu-Zn, CuO, Cu and Zn/Cu/B oxide, and its colored-metal content may vary between 28-52% Zn and 8-16% Cu. These ashes are classified as harmful wastes, due to their high Zn content, and are considered to be secondary raw materials that should be treated accordingly, from an economical viewpoint. The aim of this experimental study is to investigate the possibilities of beneficiating brass ashes by treating it with H2SO4 or (NH4)2CO3+ NH4OH mixtures. Effects of temperature, air sparging and addition of oxidizing agents, such as MnO2 and Fe2(SO4)3, are investigated on copper and zinc leaching recovery. As a result of both acidic and alkaline leaching experiments, it is observed that more than 90% of Zn and more than 65% of Cu was leached out. Two separate process flow sheets are proposed for the possible treatment of brass ashes.
In this study, the possibility of utilizing high current densities in copper rening electrolysis ... more In this study, the possibility of utilizing high current densities in copper rening electrolysis was investigated in relation to the cell design along with the surface characteristics of cathode material, and the changes observed in cell potential depending on the working conditions. Two groups of experiments were conducted. The rst series of copper rening electrolyses were carried out without any additives to the bath whereas in the second series, the eect of glue, thiourea, and chloride additions to the bath on cathodic copper was examined. Electrolysis conditions, in accordance with industrial practice, kept constant in both sets of experiments and were as follows: 45 g Cu 2+/L, 150 g H2SO4/L, 55C, electrolyte circulation of 15-20 L/min, anode dimensions of 78 74 4.5 mm, copper cathode of 47 85x0.1 mm, current density of 700 A/m2, and the aforesaid additives. Lab-scale high current density copper rening electrolysis was carried out in a specially designed cell with a unique elect...
Hydrometallurgy, 1999
The aim of this study is to investigate the utility of adding chelating agent during hydrochloric... more The aim of this study is to investigate the utility of adding chelating agent during hydrochloric acid leaching of low-grade scheelite concentrates, obtained from Uluda , Bursa (Türkiye). Examined parameters were as follows; leaching conditions, selective precipitation of tungsten salt ...
International Journal of Mineral Processing and Extractive Metallurgy
The consumption of mobile phones is increasing day by day and the replacement speed is also accel... more The consumption of mobile phones is increasing day by day and the replacement speed is also accelerating. Thus, a lot of old mobile phones and their parts need to be processed. Mobile phones contain more than 40 elements and/or materials. This experimental study aims to establish the possibilities of recovering valuable metals from waste mobile phones by using acidic leaching. The process steps include dismantling of waste mobile phones, pre-processing to liberate the materials, and directing them to final treatment processes. Prior to leaching tests, the PCBs of waste mobile phone sample are chemically analyzed and its metal contents are found as 33.22% Cu, 9.42% Fe, 1.86% Zn, 2.77% Ni, 1.63% Al, 0.4% Pb, 0.02% Co, 0.14% Ag, and 251.2 ppm Au. In the leaching experiments, sulfuric, nitric, and hydrochloric acids are used. In the sulfuric acid leaching experiments, effects of acid concentration, temperature, hydrogen peroxide addition, and leaching periods on metal dissolution efficiencies are investigated. Results are compared and discussed in relation to the types of acids. XRD analyses of feed material and leach residues are also carried out. As a result of this experimental study, 97.9% Fe leaching in 8 M H 2 SO 4 solutions, 89% Pb, 100% Ni, 90.4% Co, and 4.1% Cu leaching in 1M HNO 3 solutions, 100% Pb, and 100% Al leaching in 4 M HCl solutions in one hour are found. In conclusion, sequential leaching with different acids is recommended for the effective leaching of all metals.
Journal of Mining and Metallurgy A: Mining, 2020
The hydrometallurgical route of zinc hydroxide and synthesis of nanocrystalline ZnO is a particul... more The hydrometallurgical route of zinc hydroxide and synthesis of nanocrystalline ZnO is a particularly attractive method to recover oxidized lead and zinc from lead-zinc flotation tailings. In Turkey, lead-zinc complex/mixed ores along with high iron content are not suitable for conventional mineral processing methods and need hydrometallurgical treatments. Therefore, the control of iron during zinc processes is really important. In this study, hydrometallurgical process route for zinc recovery from Pb-Zn flotation tailings was investigated by considering the effects of H2SO4 concentration, leaching and roasting temperatures on the zinc dissolution considering the Eh-pH variations. The iron and zinc products were also individually examined by X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM) images in order to compare before and after leaching, precipitation and roasting steps. 83.1% Zn and 91.6% Cd leaching efficiencies were obtained from ...
Journal of Nanoelectronics and Optoelectronics, 2020
ZnO nanowire arrays were fabricated by hydrothermal growth on Al-doped ZnO (ZnO:Al) seed layers c... more ZnO nanowire arrays were fabricated by hydrothermal growth on Al-doped ZnO (ZnO:Al) seed layers coated on soda-lime silicate glass by sol–gel coating. The properties of the ZnO:Al seed layer were evaluated to obtain ZnO nanowires with the optimal size and length and to realize suitable adhesion of the ZnO:Al grains to the substrate. The optimal mechanical performance (adhesion and abrasion resistance) of the ZnO:Al seed layer was obtained at Al 1 at.%. The seed layers annealed between 400 and 500 C exhibited enhanced ZnO nanowire growth. Increasing the annealing temperature within this range improved the electrical and optical properties of the nanowires. Additionally, two chemical compounds, zinc acetate (ZA) and zinc nitrate (ZN), were used to compare the effects of the solution type on the hydrothermal growth. The nanowires grown in the ZA solution were thicker and had higher electrical conductivity compared to the ZN solution. The gamma transmission technique was used to determi...
Dissertation Abstracts International(USA), 1992
Two electrochemical reactions proceed simultaneously at the anode: the evolution of oxygen and th... more Two electrochemical reactions proceed simultaneously at the anode: the evolution of oxygen and the oxidation of Cr(III) to Cr(VI). The Cr(VI) diffuses from the anode compartment through the diaphragm, and it reacts with Cr(II) in the catholyte. Since the current efficiency for ...
Turk. J. Eng. Environ. Sci, 2003
The hydrometallurgical treatment of zinc sulfide concentrates involves the separation of zinc fro... more The hydrometallurgical treatment of zinc sulfide concentrates involves the separation of zinc from iron, since most zinc concentrates contain 5-12% iron. Several processes, such as hematite, magnetite, goethite and jarosite, have been developed for the removal of iron ...
Material Science & Engineering International Journal
In this study, solvent extraction is applied for extracting nickel from sulfate solutions contain... more In this study, solvent extraction is applied for extracting nickel from sulfate solutions containing iron and cobalt ions. This process can also be applied for the cleaning of waste solutions and for increasing solution concentrations after the leaching of low-grade nickel ores. Di-2-Ethylhexyl phosphoric acid (D2EHPA) was used as an extractant for this purpose. Effects of pH, aqueous/organic (A/O) phase ratio, iron, and cobalt ion contents of the solution on nickel extraction efficiency were investigated. The McCabe-Thiele diagrams for extraction and stripping steps were developed to determine the number of stages required. A total of two stages were required for 96.3% of Ni extraction and a total of two stages to strip nickel with 98% efficiency.
SCIREA Journal of Metallurgical Engineering
Turkey has a 6% share in the world of chromite mining and ferrochromium is the most important pro... more Turkey has a 6% share in the world of chromite mining and ferrochromium is the most important product in exports. The electrowinning of chromium metal follows the dissolution of chromium from chromite or high-carbon ferrochrome after its separation from gangue and metallic impurities. Although ferrochrome was found to be the most expensive starting material, the use of chromite ore is not practical because of the number of processing steps involved. Production of electrolytic chromium for Turkey becomes important because of having large reserves of chromite ores and producing an important amount of ferrochromium in the world. It is also one of the most important strategic and critical materials for nations. In the frame of electrolytic chromium production from domestic resources, laboratory-scale chromium electrolysis was conducted using a diaphragm-type cell. A synthetically prepared
Journal of Optics, 2021
ZnO nanowires were grown on a ZnO:Al polycrystalline surface by using a hydrothermal growth techn... more ZnO nanowires were grown on a ZnO:Al polycrystalline surface by using a hydrothermal growth technique. Details about the effects of the hydrothermal solution parameters (such as the curing time, curing temperature and solution molarity) and the physical properties of the solution (such as the structural characterization, surface morphology and optical and electrical properties) were determined for the ZnO nanowires. The diameter of the nanowires was increased with the curing time. The maximum transmittance was detected when the ZnO nanowires cured for 3 h. With the increasing hydrothermal growth time, the transmittance value of nanowires was decreased based upon a disorganized structure on the surface with the time due to the incline of the longer nanowires. Hence, the thicker nanowire formation affected the electrical resistivity and transmittance of the nanowires. The flower-like ZnO nanostructures were observed at the some parts of the film for the nanowires grown in 35 and 45 mM solutions. The flower-like structures had a length of * 4 lm, a root size of * 1000 nm and a tip size of * 900 nm.
The possibility of producing metallic chromium from Cr2O3 via the aluminothermic route, with no e... more The possibility of producing metallic chromium from Cr2O3 via the aluminothermic route, with no external energy supply, was the subject of this laboratory-scale research. The experimental study focused on investigating the individual effects and quantitative optimization of the charge contents, i.e., the additions of CrO3, Al powder and CaO (or BaO). The highest chromium recovery of 98% was attained with the additions of 12% CrO3 and 1.2 times the stoichiometric ally required amount of Al powder. The optimum CaO addition giving the highest chromium recovery was found when the CaO/Al weight ratio in the charge was equal to 0.3. When BaO was used, however, 95% Cr extraction efficiency was obtained at a BaO/Al weight ratio ofO. 15.
General Paper Selections, 2011
For the worldwide steel production of 725 Mt in 1993, 503 Mt of hot metal, 24 Mt of sponge iron, ... more For the worldwide steel production of 725 Mt in 1993, 503 Mt of hot metal, 24 Mt of sponge iron, and about 400 Mt of scrap were used. Today, the share of electric arc furnaces in this steel production is about 30%, meaning that every third ton of the steel produced worldwide is made by recycled scrap. This percentage is even higher in Turkey where two-thirds of the steel produced is manufactured from scrap. Although no major increase in steel production is anticipated in the near future, any that does occur will be via electric arc furnaces, which will increase the demand for scrap. In the future, a decrease in the amount of circulating scrap and a slight increase in process scrap are expected ; thus, the increased demand for scrap will be balanced mostly by the capital scrap. These developments might cause a drop in the quality of scrap. Many problems have to be solved in the future with scrap processing and recycling. This must be achieved by cooperation between the steel producin...
Material Science & Engineering International Journal, 2019
Cables, that are the indispensable parts of electrical and electronic industry, consist of plasti... more Cables, that are the indispensable parts of electrical and electronic industry, consist of plastics, aluminum, and copper. Cables are usually recycled once the electronic apparatus complete their useful lives. The old fashioned way of recovery process is to burn the plastic that covers the wire, and then recover the copper and aluminum. But this technique is extremely harmful to the environment since it releases toxic gases. Waste cables are very important source of raw material in terms of their non-ferrous metal content and it is an obligatory measure to recover these metallic contents both for economical and ecological reasons. The recovery of these metals decreases the danger of global warming. Metals can be infinitely recycled without compensating form their initial quality. Moreover, the recycling procedures generally consume much less energy than primary production methods and its CO 2 emissions are decreased. The aim of this research is to recover copper from waste electrical cables by the application of physical and chemical separation techniques. Waste cables are shredded first to decrease their size and the metallic parts are separated from plastics physically by using gravity and electrostatic separation techniques. Then copper was recovered from metallic part by smelting and refining. As a result of this experimental study, 97.2% of copper in waste cables is recovered and refined copper with 99.6 %Cu content is produced.
Materials Chemistry and Physics, 2019
Poly(methyl methacrylate) (PMMA) was reinforced by using colemanite Ca 2 B 6 O 11 •5H 2 O (CMT) t... more Poly(methyl methacrylate) (PMMA) was reinforced by using colemanite Ca 2 B 6 O 11 •5H 2 O (CMT) to increase the radiation shielding capacity of the polymer composite. CMT reinforcement effect was examined at four different CMT concentration levels (such as 5, 15, 30 and 40 wt. %) to investigate radiation protective shielding properties of PMMA / CMT composite. The effect of the CMT reinforcement on the radiation shielding capacity was determined to use the composite at the mixed fields of neutrons and gamma rays. For this purpose, the polymer composite samples were prepared by using in-situ polymerization with atom transfer radical polymerization (ATRP) technique. Radiation shielding capacity was experimentally assessed by using gamma and neutron attenuation tests. The gamma-ray shielding capacity of the composite was examined by using Cs-137 radioisotope and the experimental results of gamma transmittance were compared with theoretical calculations by using WinXCOM. Neutron transmission tests were performed by using a neutron howitzer (239 Pu-Be neutron source). Radiation shielding performance of PMMA/CMT composite was examined by the determination of the attenuation coefficient (µ) and the half-value layer (HVL). CMT reinforcement of PMMA supported to increase the radiation shielding capacity by 11.1 % for gamma photons of Cs-137 radioisotope and 38.56 % for neutrons emitted from Pu-Be neutron source.
Journal of Physics: Conference Series, 2018
Poly(methyl methacrylate) PMMA was prepared by using Atom Transfer Radical Polymerization techniq... more Poly(methyl methacrylate) PMMA was prepared by using Atom Transfer Radical Polymerization technique. The production of PMMA as thermoplastic polymer was executed as an effective way by using the living polymerization technique. The changes in magnetisation properties of PMMA were determined with the rise of the polymerisation temperature from 45 °C in argon to the room temperature in air. Hence the excess oxygen effect on the magnetic properties was investigated to examine the changes of the magnetic properties depending on the air-sensitivity of the PMMA with the decrease of the temperature. The hysteresis loops indicated that the production ambient conditions of the PMMA has affected the magnetic properties and the magnetic properties variated from diamagnetic to paramagnetic ordering with the decrease of the polymerization temperature in the excess oxygen.
Journal of Electronic Materials, 2005
In this study, the effects of current density and bath temperature on the hardness, thickness, an... more In this study, the effects of current density and bath temperature on the hardness, thickness, and morphology of boride layer are systematically investigated. The electrochemical boride coating on steel substrates is carried out at various current densities (50-700 mA/cm 2) and bath temperatures (800-1000°C) at constant electrolyte composition and electrolysis time. The FeB, Fe 2 B, and Fe 3 B phases are detected by the x-ray diffraction method. The hardness of the boride layer reaches approximately 1800 HV on the surface and gradually decreases toward the matrix. The optimum current density and electrolyte temperature for the boriding of low-alloy steel are determined as 200 mA/cm 2 and 900°C, respectively.
Hydrometallurgy, 1999
The aim of this study is to investigate the utility of adding chelating agent during hydrochloric... more The aim of this study is to investigate the utility of adding chelating agent during hydrochloric acid leaching of low-grade scheelite concentrates, obtained from Uluda , Bursa (Türkiye). Examined parameters were as follows; leaching conditions, selective precipitation of tungsten salt ...
Scandinavian Journal of Metallurgy, 2002
Scheelite concentrates, obtained from Uludag, Bursa (Türkiye), containing roughly 50% W, are trea... more Scheelite concentrates, obtained from Uludag, Bursa (Türkiye), containing roughly 50% W, are treated by the chelate-added acidic leaching route. Dissolved tungsten ions are then selectively precipitated by the addition of "ammonia ion containing" reagents-either organic or inorganic, and thus are purified from other ions present in the solution. The optimum precipitation conditions are investigated with the aim of producing pure tungsten oxide via thermal breakdown process. Weight loss ratios of the samples vary between 8.7 and 9.6% at the end of two-hour thermal breakdown process. This amount validates the formula suggested for the complex salt; (NH 4) 3 PW 12 O 40 •9H 2 O. Tungsten trioxide obtained, on the other hand, can be suitably employed in tungsten-related powder metallurgy applications with its extremely low impurity content of 0.04% Mo, 0.15% SiO 2 , 0.06% Fe and 0.03% Al.
Developments in Mineral Processing, 2000
Slags formed during brass smelting contain a significant amount of metallic value. The glassy and... more Slags formed during brass smelting contain a significant amount of metallic value. The glassy and oxidized portion of the ground slag, usually referred to as "brass ash", consists of compounds such as ZnO, ZnO-SiO2, Cu-Zn, CuO, Cu and Zn/Cu/B oxide, and its colored-metal content may vary between 28-52% Zn and 8-16% Cu. These ashes are classified as harmful wastes, due to their high Zn content, and are considered to be secondary raw materials that should be treated accordingly, from an economical viewpoint. The aim of this experimental study is to investigate the possibilities of beneficiating brass ashes by treating it with H2SO4 or (NH4)2CO3+ NH4OH mixtures. Effects of temperature, air sparging and addition of oxidizing agents, such as MnO2 and Fe2(SO4)3, are investigated on copper and zinc leaching recovery. As a result of both acidic and alkaline leaching experiments, it is observed that more than 90% of Zn and more than 65% of Cu was leached out. Two separate process flow sheets are proposed for the possible treatment of brass ashes.
In this study, the possibility of utilizing high current densities in copper rening electrolysis ... more In this study, the possibility of utilizing high current densities in copper rening electrolysis was investigated in relation to the cell design along with the surface characteristics of cathode material, and the changes observed in cell potential depending on the working conditions. Two groups of experiments were conducted. The rst series of copper rening electrolyses were carried out without any additives to the bath whereas in the second series, the eect of glue, thiourea, and chloride additions to the bath on cathodic copper was examined. Electrolysis conditions, in accordance with industrial practice, kept constant in both sets of experiments and were as follows: 45 g Cu 2+/L, 150 g H2SO4/L, 55C, electrolyte circulation of 15-20 L/min, anode dimensions of 78 74 4.5 mm, copper cathode of 47 85x0.1 mm, current density of 700 A/m2, and the aforesaid additives. Lab-scale high current density copper rening electrolysis was carried out in a specially designed cell with a unique elect...
Hydrometallurgy, 1999
The aim of this study is to investigate the utility of adding chelating agent during hydrochloric... more The aim of this study is to investigate the utility of adding chelating agent during hydrochloric acid leaching of low-grade scheelite concentrates, obtained from Uluda , Bursa (Türkiye). Examined parameters were as follows; leaching conditions, selective precipitation of tungsten salt ...
International Journal of Mineral Processing and Extractive Metallurgy
The consumption of mobile phones is increasing day by day and the replacement speed is also accel... more The consumption of mobile phones is increasing day by day and the replacement speed is also accelerating. Thus, a lot of old mobile phones and their parts need to be processed. Mobile phones contain more than 40 elements and/or materials. This experimental study aims to establish the possibilities of recovering valuable metals from waste mobile phones by using acidic leaching. The process steps include dismantling of waste mobile phones, pre-processing to liberate the materials, and directing them to final treatment processes. Prior to leaching tests, the PCBs of waste mobile phone sample are chemically analyzed and its metal contents are found as 33.22% Cu, 9.42% Fe, 1.86% Zn, 2.77% Ni, 1.63% Al, 0.4% Pb, 0.02% Co, 0.14% Ag, and 251.2 ppm Au. In the leaching experiments, sulfuric, nitric, and hydrochloric acids are used. In the sulfuric acid leaching experiments, effects of acid concentration, temperature, hydrogen peroxide addition, and leaching periods on metal dissolution efficiencies are investigated. Results are compared and discussed in relation to the types of acids. XRD analyses of feed material and leach residues are also carried out. As a result of this experimental study, 97.9% Fe leaching in 8 M H 2 SO 4 solutions, 89% Pb, 100% Ni, 90.4% Co, and 4.1% Cu leaching in 1M HNO 3 solutions, 100% Pb, and 100% Al leaching in 4 M HCl solutions in one hour are found. In conclusion, sequential leaching with different acids is recommended for the effective leaching of all metals.
Journal of Mining and Metallurgy A: Mining, 2020
The hydrometallurgical route of zinc hydroxide and synthesis of nanocrystalline ZnO is a particul... more The hydrometallurgical route of zinc hydroxide and synthesis of nanocrystalline ZnO is a particularly attractive method to recover oxidized lead and zinc from lead-zinc flotation tailings. In Turkey, lead-zinc complex/mixed ores along with high iron content are not suitable for conventional mineral processing methods and need hydrometallurgical treatments. Therefore, the control of iron during zinc processes is really important. In this study, hydrometallurgical process route for zinc recovery from Pb-Zn flotation tailings was investigated by considering the effects of H2SO4 concentration, leaching and roasting temperatures on the zinc dissolution considering the Eh-pH variations. The iron and zinc products were also individually examined by X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM) images in order to compare before and after leaching, precipitation and roasting steps. 83.1% Zn and 91.6% Cd leaching efficiencies were obtained from ...
Journal of Nanoelectronics and Optoelectronics, 2020
ZnO nanowire arrays were fabricated by hydrothermal growth on Al-doped ZnO (ZnO:Al) seed layers c... more ZnO nanowire arrays were fabricated by hydrothermal growth on Al-doped ZnO (ZnO:Al) seed layers coated on soda-lime silicate glass by sol–gel coating. The properties of the ZnO:Al seed layer were evaluated to obtain ZnO nanowires with the optimal size and length and to realize suitable adhesion of the ZnO:Al grains to the substrate. The optimal mechanical performance (adhesion and abrasion resistance) of the ZnO:Al seed layer was obtained at Al 1 at.%. The seed layers annealed between 400 and 500 C exhibited enhanced ZnO nanowire growth. Increasing the annealing temperature within this range improved the electrical and optical properties of the nanowires. Additionally, two chemical compounds, zinc acetate (ZA) and zinc nitrate (ZN), were used to compare the effects of the solution type on the hydrothermal growth. The nanowires grown in the ZA solution were thicker and had higher electrical conductivity compared to the ZN solution. The gamma transmission technique was used to determi...
Dissertation Abstracts International(USA), 1992
Two electrochemical reactions proceed simultaneously at the anode: the evolution of oxygen and th... more Two electrochemical reactions proceed simultaneously at the anode: the evolution of oxygen and the oxidation of Cr(III) to Cr(VI). The Cr(VI) diffuses from the anode compartment through the diaphragm, and it reacts with Cr(II) in the catholyte. Since the current efficiency for ...
Turk. J. Eng. Environ. Sci, 2003
The hydrometallurgical treatment of zinc sulfide concentrates involves the separation of zinc fro... more The hydrometallurgical treatment of zinc sulfide concentrates involves the separation of zinc from iron, since most zinc concentrates contain 5-12% iron. Several processes, such as hematite, magnetite, goethite and jarosite, have been developed for the removal of iron ...
Material Science & Engineering International Journal
In this study, solvent extraction is applied for extracting nickel from sulfate solutions contain... more In this study, solvent extraction is applied for extracting nickel from sulfate solutions containing iron and cobalt ions. This process can also be applied for the cleaning of waste solutions and for increasing solution concentrations after the leaching of low-grade nickel ores. Di-2-Ethylhexyl phosphoric acid (D2EHPA) was used as an extractant for this purpose. Effects of pH, aqueous/organic (A/O) phase ratio, iron, and cobalt ion contents of the solution on nickel extraction efficiency were investigated. The McCabe-Thiele diagrams for extraction and stripping steps were developed to determine the number of stages required. A total of two stages were required for 96.3% of Ni extraction and a total of two stages to strip nickel with 98% efficiency.
SCIREA Journal of Metallurgical Engineering
Turkey has a 6% share in the world of chromite mining and ferrochromium is the most important pro... more Turkey has a 6% share in the world of chromite mining and ferrochromium is the most important product in exports. The electrowinning of chromium metal follows the dissolution of chromium from chromite or high-carbon ferrochrome after its separation from gangue and metallic impurities. Although ferrochrome was found to be the most expensive starting material, the use of chromite ore is not practical because of the number of processing steps involved. Production of electrolytic chromium for Turkey becomes important because of having large reserves of chromite ores and producing an important amount of ferrochromium in the world. It is also one of the most important strategic and critical materials for nations. In the frame of electrolytic chromium production from domestic resources, laboratory-scale chromium electrolysis was conducted using a diaphragm-type cell. A synthetically prepared
Journal of Optics, 2021
ZnO nanowires were grown on a ZnO:Al polycrystalline surface by using a hydrothermal growth techn... more ZnO nanowires were grown on a ZnO:Al polycrystalline surface by using a hydrothermal growth technique. Details about the effects of the hydrothermal solution parameters (such as the curing time, curing temperature and solution molarity) and the physical properties of the solution (such as the structural characterization, surface morphology and optical and electrical properties) were determined for the ZnO nanowires. The diameter of the nanowires was increased with the curing time. The maximum transmittance was detected when the ZnO nanowires cured for 3 h. With the increasing hydrothermal growth time, the transmittance value of nanowires was decreased based upon a disorganized structure on the surface with the time due to the incline of the longer nanowires. Hence, the thicker nanowire formation affected the electrical resistivity and transmittance of the nanowires. The flower-like ZnO nanostructures were observed at the some parts of the film for the nanowires grown in 35 and 45 mM solutions. The flower-like structures had a length of * 4 lm, a root size of * 1000 nm and a tip size of * 900 nm.
The possibility of producing metallic chromium from Cr2O3 via the aluminothermic route, with no e... more The possibility of producing metallic chromium from Cr2O3 via the aluminothermic route, with no external energy supply, was the subject of this laboratory-scale research. The experimental study focused on investigating the individual effects and quantitative optimization of the charge contents, i.e., the additions of CrO3, Al powder and CaO (or BaO). The highest chromium recovery of 98% was attained with the additions of 12% CrO3 and 1.2 times the stoichiometric ally required amount of Al powder. The optimum CaO addition giving the highest chromium recovery was found when the CaO/Al weight ratio in the charge was equal to 0.3. When BaO was used, however, 95% Cr extraction efficiency was obtained at a BaO/Al weight ratio ofO. 15.
General Paper Selections, 2011
For the worldwide steel production of 725 Mt in 1993, 503 Mt of hot metal, 24 Mt of sponge iron, ... more For the worldwide steel production of 725 Mt in 1993, 503 Mt of hot metal, 24 Mt of sponge iron, and about 400 Mt of scrap were used. Today, the share of electric arc furnaces in this steel production is about 30%, meaning that every third ton of the steel produced worldwide is made by recycled scrap. This percentage is even higher in Turkey where two-thirds of the steel produced is manufactured from scrap. Although no major increase in steel production is anticipated in the near future, any that does occur will be via electric arc furnaces, which will increase the demand for scrap. In the future, a decrease in the amount of circulating scrap and a slight increase in process scrap are expected ; thus, the increased demand for scrap will be balanced mostly by the capital scrap. These developments might cause a drop in the quality of scrap. Many problems have to be solved in the future with scrap processing and recycling. This must be achieved by cooperation between the steel producin...
Material Science & Engineering International Journal, 2019
Cables, that are the indispensable parts of electrical and electronic industry, consist of plasti... more Cables, that are the indispensable parts of electrical and electronic industry, consist of plastics, aluminum, and copper. Cables are usually recycled once the electronic apparatus complete their useful lives. The old fashioned way of recovery process is to burn the plastic that covers the wire, and then recover the copper and aluminum. But this technique is extremely harmful to the environment since it releases toxic gases. Waste cables are very important source of raw material in terms of their non-ferrous metal content and it is an obligatory measure to recover these metallic contents both for economical and ecological reasons. The recovery of these metals decreases the danger of global warming. Metals can be infinitely recycled without compensating form their initial quality. Moreover, the recycling procedures generally consume much less energy than primary production methods and its CO 2 emissions are decreased. The aim of this research is to recover copper from waste electrical cables by the application of physical and chemical separation techniques. Waste cables are shredded first to decrease their size and the metallic parts are separated from plastics physically by using gravity and electrostatic separation techniques. Then copper was recovered from metallic part by smelting and refining. As a result of this experimental study, 97.2% of copper in waste cables is recovered and refined copper with 99.6 %Cu content is produced.
Materials Chemistry and Physics, 2019
Poly(methyl methacrylate) (PMMA) was reinforced by using colemanite Ca 2 B 6 O 11 •5H 2 O (CMT) t... more Poly(methyl methacrylate) (PMMA) was reinforced by using colemanite Ca 2 B 6 O 11 •5H 2 O (CMT) to increase the radiation shielding capacity of the polymer composite. CMT reinforcement effect was examined at four different CMT concentration levels (such as 5, 15, 30 and 40 wt. %) to investigate radiation protective shielding properties of PMMA / CMT composite. The effect of the CMT reinforcement on the radiation shielding capacity was determined to use the composite at the mixed fields of neutrons and gamma rays. For this purpose, the polymer composite samples were prepared by using in-situ polymerization with atom transfer radical polymerization (ATRP) technique. Radiation shielding capacity was experimentally assessed by using gamma and neutron attenuation tests. The gamma-ray shielding capacity of the composite was examined by using Cs-137 radioisotope and the experimental results of gamma transmittance were compared with theoretical calculations by using WinXCOM. Neutron transmission tests were performed by using a neutron howitzer (239 Pu-Be neutron source). Radiation shielding performance of PMMA/CMT composite was examined by the determination of the attenuation coefficient (µ) and the half-value layer (HVL). CMT reinforcement of PMMA supported to increase the radiation shielding capacity by 11.1 % for gamma photons of Cs-137 radioisotope and 38.56 % for neutrons emitted from Pu-Be neutron source.
Journal of Physics: Conference Series, 2018
Poly(methyl methacrylate) PMMA was prepared by using Atom Transfer Radical Polymerization techniq... more Poly(methyl methacrylate) PMMA was prepared by using Atom Transfer Radical Polymerization technique. The production of PMMA as thermoplastic polymer was executed as an effective way by using the living polymerization technique. The changes in magnetisation properties of PMMA were determined with the rise of the polymerisation temperature from 45 °C in argon to the room temperature in air. Hence the excess oxygen effect on the magnetic properties was investigated to examine the changes of the magnetic properties depending on the air-sensitivity of the PMMA with the decrease of the temperature. The hysteresis loops indicated that the production ambient conditions of the PMMA has affected the magnetic properties and the magnetic properties variated from diamagnetic to paramagnetic ordering with the decrease of the polymerization temperature in the excess oxygen.
XVII Balkan Mineral Processing Congress
In this study, strontium carbonate precipitation from strontium sulphide solution was investigate... more In this study, strontium carbonate precipitation from strontium sulphide solution was investigated. Experimental study was carried out to determine the effects of precipitation period (5, 15, 30, 60 min), sodium carbonate concentration (1, 1.1, 1.25, 1.5, and 2M) and temperature (25, 55, 75°C). The SrS solution used in the experiments was obtained by dissolving the black ash produced by our previous work in pure water. The concentration of Sr was determined to be 22.23 g/L by AAS analysis. The XRD results showed that the solid was SrCO3. The intensity of XRD peaks increased with increasing temperature. The effect of precipitation period for efficiency is too low to be taken into account. As the sodium carbonate concentration increased, SrCO3 precipitation yield increased. Finally, AAS analysis showed that maximum recovery was obtained as 97.1% Sr under the conditions of 2 M Na2CO3, 75°C, 60 min.