Sharif Digital Repository

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... 

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... 

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... 

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... 

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...