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hydrometallurgy
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Oxidation pretreatment for enhancing desulfurization of coal with sodium butoxide
, Article Minerals Engineering ; Volume 17, Issue 4 , 2004 , Pages 545-552 ; 08926875 (ISSN) ; Rezai, B ; Vossoughi, M ; Osanloo, M ; Abdollahi, M ; Sharif University of Technology
2004
Abstract
A sample of Tabas coal from Iran was oxidized using air, peroxyacetic acid (PAA), and PAA+air as a pretreatment for desulfurization with sodium butoxide in a batch reactor. The effects of air oxidation temperature, PAA oxidation time, sodium butoxide reaction time and temperature, solvent concentration and particle size on the reduction of sulfur were investigated. The PAA+air oxidation pretreatment was the most effective method for enhancing sulfur removal. This procedure increased pyritic sulfur removal by approximately 15% and organic sulfur removal by 20% in leaching with sodium butoxide. Increasing the temperature from 25 (unoxidized) to 100 °C on air oxidized samples, increased sulfur...
Synergistic effect of MEHPA on co-extraction of zinc and cadmium with DEHPA
, Article Minerals Engineering ; Volume 17, Issue 1 , 2004 , Pages 89-92 ; 08926875 (ISSN) ; Moradkhani, D ; Darvishi, D ; Askari, M ; Behnian, D ; Sharif University of Technology
2004
Abstract
Simultaneous extraction of zinc and cadmium by a mixture of di-2-ethyl hexyl phosphoric acid (DEHPA) and mono-2-ethyl hexyl phosphoric acid (MEHPA), and the synergistic effect of MEHPA on co-extraction of zinc and cadmium with DEHPA have been investigated. It was shown that the extraction of zinc and cadmium by DEHPA and/or MEHPA can be increased by an increase of pH. The results also illustrate that the pH0.5 of zinc, by increase in MEHPA from 0.1 to 8 vol%, did not vary significantly while that of cadmium varies from 0.63 to 2.4. In other words MEHPA prevents selective extraction of zinc from aqueous media containing both zinc and cadmium. Studies on the selective separation parameter...
Nickel Recovery from Spent Catalyst of Reformers
, M.Sc. Thesis Sharif University of Technology ; Halali, Mohammad (Supervisor)
Abstract
In this research, Nickel recovery has been investigated from spent catalyst (NiO/Al2O3) in reformers of direct reduction iron plant (Midrex). Genetic Algorithm method was applied for screening and optimization of the parameters affecting on the Ni dissolution in sulphuric acid by means of Design Expert Software. In accordance with the results, temperature, time, acid concentration and particle size were introduced as the effective parameters on the catalyst leaching. In the next step, the optimization experiments, the optimal parameters were achieved as following: Temperature = 95 C, Acid concentration = 5 Molar, Time = 255 minute, Stirring speed = 600 rpm, Particle size = 50-60 micron and...
Antimony Extraction from Stibnite Ore Using Alkaline Hydrometallurgical Method
, M.Sc. Thesis Sharif University of Technology ; Yoozbashizadeh, Hossein (Supervisor)
Abstract
In this research, antimony extraction by hydrometallurgical method has been investigated using an alkaline medium. Stibnite ore, as a source of antimony was leached in alkali potassium hydroxide solution. Furthermore, related kinetic equations and process factors were also studied. It was determined that optimum conditions occure when the concentration of KOH is 0.5 mol /L, the solid to liquid ratio is 100 g/L, the reaction temperature is 25 °C, and the process is performed in 115 minutes. It was found that diffusion through the ash layer controls the reaction kinetics during the first 60 minutes. Finally, for the first time, the effect of different parameters on antimony electrowinning was...
Effect of Cu2+ on Leaching of Chalcopyrite in Chloride Media and Investigation of Thermodynamic and Kinetics of Process and Comparison with Sulfate Media
, M.Sc. Thesis Sharif University of Technology ; Yoozbashi Zadeh, Hossein (Supervisor)
Abstract
High advantages of hydrometallurgy have led to its recent development in metal extraction. Many investigations have been carried out on applying hydrometallurgy processes on copper extraction. In this study, Chalcopyrite concentrate produced in Sarcheshmeh copper plant was subjected to oxidative leaching investigation by cupric ion to determine the effect of several parameters on the copper and iron dissolution, included temperature of leaching, time of holding and cupric concentration as oxidant agent in a range of 38-97°C, 1.5-8.5 hours and 0.2-0.8 M respectively. The leaching media was chloride providing with 3M HCl 37% and CuCl2. The experiments were designed by central composite...
Hydrometallurgical treatment of tailings with high zinc content
, Article Hydrometallurgy ; Volume 82, Issue 1-2 , 2006 , Pages 54-62 ; 0304386X (ISSN) ; Rashchi, F ; Sadrnezhaad, S. K ; Sharif University of Technology
2006
Abstract
Zinc exists as smithsonite and hemimorphite in the lead flotation tailings from the Dandi mineral processing plant in north western Iran. In this research, zinc-rich tailings produced in the Dandi plant were characterized mineralogically and a leaching study was carried out to assess the effect of several parameters on the kinetics of zinc dissolution. Parameters studied included: sulfuric acid concentration, reaction time, temperature and slurry density. It was found that leaching is controlled by a single rate-controlling step with an activation energy of 23.5 kJ/mol. To overcome some of the filtration problems associated with polymerization of silicic acid, lime was added as a coagulant....
Optimization of Leaching of Platinum Group Metals from Spent Car Catalytic Converters
, M.Sc. Thesis Sharif University of Technology ; Halali, Mohammad (Supervisor)
Abstract
The catalytic converter converts 95 to 99 percent of the vehicle exhaust gases into environmentally friendly gases, which are installed between the engine and the vehicle's exhaust cistern. The catalyst contained in the converters includes a ceramic structure commonly used as an alumina, coated with metal catalyst of expensive metals of the platinum group (platinum, palladium and rhodium). The purpose of this project is to optimize the recovery of platinum group metals from automotive catalytic converters by hydrometallurgy by hydrochloric acid and oxygenated water as an additive using Design Expert software. In this project, using the factorial design, the effect of parameters of...
Recovery of Gold Electronic scraps(PCB) By Hydrometallurgical process
, M.Sc. Thesis Sharif University of Technology ; Yozbashizadeh, Hossain (Supervisor)
Abstract
Increasing demand for Gold in electronic devices and catalysts, and its high cost, makes it crucial to recover the Gold from waste electronic devices such as Printed Circuit Boards. In this research, recovery of Gold by hydrometallurgical process based on heating the scraps along with a strong oxidizing agent, Potassium Persulphate, which is “eco-friendly” or “green”process is concerned. Recovery of Gold achieved by simple filtration process following by washing with water and nitric acid in order to dissolve impurities such as Al and Sn. The systematical and analytical evaluation method of Taguchi quality engineering has been applied for the leaching to evaluate the optimal experimental...
The separation of cadmium from zinc with a synergistic mixture of nonylsalicylic acid and triisobutylphosphine sulphide
, Article Hydrometallurgy ; Volume 78, Issue 1-2 SPEC. ISS , 2005 , Pages 129-136 ; 0304386X (ISSN) ; Urbani, M ; Cheng, C. Y ; Askari, M ; Bastani, D ; Sharif University of Technology
2005
Abstract
Metal pH50 and ΔpH50 values were determined and compared for a number of organic systems to select a synergistic system for the separation of Cd from Zn. The largest ΔpH50(Zn-Cd) value was obtained with HRJ-4277 (nonylsalicylic acid)/Cyanex 471X (triisobutyl phosphine sulphide or TIBPS) system and reached 1.53 pH units, indicating excellent separation of Cd from Zn with this system. Shellsol 2046 was chosen as the diluent of the system due to its larger ΔpH50(Zn-Cd) and excellent phase separation compared with other diluents. Distribution isotherms and subsequent McCabe-Thiele diagrams indicate that 99% Cd could be extracted in two stages at pH 3.80 and A / O ratio of 1.5 : 1. The extraction...
Synergistic effect of Cyanex 272 and Cyanex 302 on separation of cobalt and nickel by D2EHPA
, Article Hydrometallurgy ; Volume 77, Issue 3-4 , 2005 , Pages 227-238 ; 0304386X (ISSN) ; Haghshenas, D. F ; Keshavarz Alamdari, E ; Sadrnezhaad, S. K ; Halali, M ; Sharif University of Technology
2005
Abstract
Synergistic effects of Cyanex 272 mixed with D2EHPA and Cyanex 302 mixed with D2EHPA were investigated for the separation of cobalt and nickel from a dilute sulfate media with the aim of reducing the reagent cost. Selective extraction of cobalt over nickel improved with respect to D2EHPA, but worsened with respect to Cyanex 272. By the application of the slope analysis method, the stoichiometric coefficient of the extractant was found to be four for cobalt and five for nickel, in a mixture of D2EHPA with Cyanex 302. However, it was four for both cobalt and nickel in a mixture of D2EHPA with Cyanex 272. Fourier Transform Infrared Spectroscopy (FT-IR) was utilized to examine the...
Leaching recovery of zinc, cobalt and manganese from zinc purification residue
, Article International Journal of Engineering, Transactions B: Applications ; Volume 20, Issue 2 , 2007 , Pages 133-140 ; 1728-144X (ISSN) ; Darvishi, D ; Mos'hefi Shabestari, Z ; Keshavarz Alamdari, E ; Sadrnezhaad, S. K ; Sharif University of Technology
Materials and Energy Research Center
2007
Abstract
This paper reports on the recovery of zinc, cobalt and manganese by two-step leaching of zinc-plants purification residue with sulfuric acid. The residue, hot filter press cake (HFC), contains 14 % ZnO, 4.8 % Co 3O4 and 22.9 % MnO. Effects of different parameters are determined and used to optimize the process. With acid to hot filter press cake (HFC) stoichiometry of 0.85, acid concentration of 30 g/L and temperature of 25°C, it took two minutes to separate zinc from zinc plant residue. Hydrogen peroxide (H2O2) was used as an oxidation agent. The most suitable acid concentration for leaching of both cobalt and manganese was 50 g/L. Recovery of cobalt and manganese increased with peroxide...