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Öğe Examination of leaching of malachite ore in acetic acid/ammonium acetate solutions(Chamber of Mining Engineers of Turkey, 2013) Demirkiran N.; Asin C.; Ekmekyapar A.; Bayrakçi N.; Tanaydin M.K.Organic acids have been used as leach reagent in hydrometallurgical processing of some ores in recent years. In this study, the usability of the solutions containing acetic acid and ammonium acetate for the leaching of malachite ore was investigated. The effects of acetic acid/ammonium acetate ratio, temperature, solid to liquid ratio, and particle size on the leaching rate of malachite ore were examined. It was determined that the leaching efficiency was higher in case of high acid and low salt concentrations. It was determined that almost all copper in malachite ore was passed into solution medium. The kinetic analysis of the leaching process was done, and it was found that it followed the diffusion model through the product layer.Öğe Examination of leaching of malachite ore in ammonia/ammonium chloride solutions(Chamber of Mining Engineers of Turkey, 2013) Tanaydin M.K.; Demirkiran N.; Ekmekyapar A.In this work, the leaching of malachite, an oxidized copper ore, in ammonia/ammonium chloride solution was studied. The effects of the reaction temperature, ammonia and ammonium chloride concentration, and stirring speed on the leaching of malachite were examined. According to findings obtained, it was determined that ammonia/ammonium chloride ratio has a considerable effect on the dissolution of ore. It was observed that the dissolution rate increased with increasing temperature, and the stirring speed has not a considerable effect. The kinetic analysis of the leaching process was performed by applying the heterogeneous reaction models, and it was found that the leaching reaction followed the mixed kinetic controlled model. It was determined that the leaching reaction was controlled by diffusion at low temperatures, while it was controlled by chemical reaction at high temperatures. The activation energies for two consecutive mechanisms were calculated to be 19.5 and 50.8 kJ/mol, respectively.Öğe Immobilization of glucose oxidase in GLYMO/MTEO sol-gel film for glucose biosensor application(2012) Demirkiran N.; Ekinci E.An electrochemical biosensor was developed by using the sol-gel coating solution. The modified platinum electrode used in the study was constructed by immobilization of glucose oxidase under a layer of sol-gel film. The coating solution was prepared by using GLYMO, and MTEOS. Electrochemical measurements were carried out amperometrically by determining hydrogen peroxide produced by the enzymatic reaction between glucose and glucose oxidase. It was observed that the amperometric response of the enzyme electrode was linear for glucose concentrations in the range from 2 to 10 mM. The response time of the biosensor to reach a steady-state current value was approximately 80 s. The glucose selectivity of the biosensor was determined in the presence of some interfering substances, such as lactose, sucrose, urea, uric acid, oxalic acid, and ascorbic acid. It was observed that the interfering molecules did not cause any observable signal. The stability of the sensor was investigated, and it was found hat the initial sensor response decreased approximately 44% over a period of 30 days of storage in dry state at 4 °C.Öğe Immobilization of glucose oxidase in silica sol-gel film for application to biosensor and amperometric determination of glucose(2012) Demirkiran N.; Ekinci E.; Asiltürk M.In this study, an electrochemical biosensor was developed by using a sol-gel coating solution. The modified platinum electrode used in the study was constructed by immobilization of glucose oxidase under a layer of sol-gel film. The sol-gel coating solution was prepared by using GLYMO, TEOS, and MTEOS. Electrochemical measurements were carried out amperometrically by determining hydrogen peroxide produced by the enzymatic reaction between glucose and glucose oxidase. The amperometric responses of the resulting enzymatic electrode to glucose were rapid. It was observed that the amperometric response of the enzymatic electrode was linear for glucose concentrations in the range from 2 to 18 mM with 50 s response time. LOD and LOQ for the enzymatic electrode were calculated to be 0.055 mM and 0.184 mM, respectively. It was determined that the developed biosensor had an acceptable reproducibility. The selectivity of the biosensor was determined in the presence of some interfering substances, such as lactose, sucrose, urea, uric acid, oxalic acid, and ascorbic acid. The stability of the biosensor was investigated, and it was found that the sensor response decreased by 59% of its initial response over a period of 30 days of storage in dry conditions at 4 °C.Öğe Investigation of the usability of oleic acid as extractant in copper extraction from aqueous solutions(Chamber of Mining Engineers of Turkey, 2013) Tanaydin M.K.; Demirkiran N.; Ekmekyapar A.Solvent extraction is applied to gain the metal from the leach solution or refine the solution. In this work, the usability of oleic acid as extractant for the gain of copper by solvent extraction method from aqueous solutions was examined. The effects of the solvent type, temperature, organic phase/aqueous phase ratio, stirring speed, and initial pH value on the extraction efficiency were studied. It was determined that the recovery efficiency of copper is low in case of using a solvent, while it is higher in case of using only oleic acid. It was observed that the amount of copper removed aqueous phase increased with increasing the stirring speed and initial pH value.Öğe Preparation of calcined ulexite for use in the leaching process(2011) Demirkiran N.; Künkül A.Most of boron minerals, such as colemanite, tincal and ulexite, include water of crystallization. Applying the calcination process, they lose some of their water of hydration at various calcination temperatures. Dehydration process can be applied due to technological and economical reasons. A porous solid may obtain by calcination process, and the rate of boric acid extraction from mineral can be increased. The effects of some parameters to prepare calcined ulexite for purpose of use in the leaching process were investigated in this study. The dehydration of ulexite was performed by using isothermal and nonisothermal methods. The effects of temperature, heating time, particle size and sample weight on the weight loss of ulexite were investigated. It was determined that an increase in dehydration temperature and heating time, and decrease in sample weight caused a significant increase in the weight loss of ulexite. The change in particle size does not have any significant effect on the dehydration rate.Öğe RECOVERY OF ZINC AND MANGANESE FROM WASTE ALKALINE BATTERY POWDER BY TWO-STAGE LEACHING PROCESS(Chamber of Mining Engineers of Turkey, 2019) Özdemir G.D.T.; Demirkiran N.In this work, the selective dissolution of zinc and manganese in the waste alkaline battery powders was investigated by applying two-stage leaching method. In the first-stage of leaching, zinc in the battery powder was dissolved using NaOH solutions. The solid residue containing manganese was separated from the solution by filtration and used in the second leaching step. Sulfuric acid solutions containing molasses was used as leaching agent in the second-stage leaching treatment. In each leaching step, the effects of solution concentration, temperature, stirring speed and solid to liquid ratio on the dissolution of zinc and manganese were examined. The findings obtained showed that the experimental parameters had a significant effect on the dissolution of zinc and manganese. It was observed that the dissolution efficiency for both metal increased with an increase in the solution concentration, temperature and stirring speed, and with a decrease in the solid to liquid ratio. At the experimental conditions of a sodium hydroxide concentration of 1.5 mol/L, a reaction temperature of 40°C, a solid to liquid ratio of 2/500 g/mL, a stirring speed of 500 rpm, and a reaction time of 120 min., it was determined that 77% of zinc in waste battery powder was dissolved. While concentration of sulfuric acid, temperature, solid to liquid ratio, stirring speed, and reaction time were 1.5 mol/L, 50°C, 2/500 g/mL, 500 rpm, and 120 min. respectively, it was found that 85% of manganese in the leach residue was dissolved. © 2019 Union of Chambers of Engineers and Architects of Turkey. All rights reserved.
