Sharif Digital Repository

In this work hydrometallurgical route for processing spent commercial catalysts (Co/Al2O3) are investigated for leaching the Cobalt component. The used catalysts were initially pre-oxidized at 500 °C and 5 h in order to eliminate coke and other volatile species present. Pre-oxidized catalysts were dissolved in solvents such as H2SO4, HNO3, HCl and H2O at 80-90 °C, and the remaining residues separated from the solution. These experiments were performed at different concentrations, presence and absence H2O2 solution. Also effect of reflux on leaching process investigated. The result show the yield of the pre-oxidized catalysts extracted with highly concentration of extractant is higher than... 

Platinum is one of the most used catalysts in refining and petrochemical industries. Also, Platinum uses in other industries like automobile catalytic convertor. As respect to importance of Platinum in these industries, growth of its consumption in recent decades and its very high price, recovery of Platinum is essential. Hence, many of various methods including hydro-metallurgy are applied. In despite of these wide spreading experimental investigations, due to low information about the reactions and the nature of reaction products, a few investigations were done on kinetics of Platinum recovery. A new method that used iodine solution to extract Platinum from spent reforming catalysts was... 

This research tries to simulate the conditions of nanosized TiO2 powder production from pure commercial precursors, to produce nanosized TiO2 powder by leaching kahnouj ilmenite concentrate. For this purpose, the ilmenite concentrate was first oxidized to study the kinetics and optimization of oxidation process before leaching. Then the effect of pre-oxidation on the iron and titanium leaching efficiency was studied. Then the reductive leaching of concentrate using zinc and iron powders as reducing agent for Fe (III) to Fe (II) reaction was studied. The effect of reducing agent as well as oxidation and reduction on the leaching efficiency was studied. At the next step the optimum conditions... 

Indium is one of the most important metals in electronics and nuclear industry with increasing demand. The most important application of Indium is in the preparation of thin films containing this metal in LCD manufacturing, television, laptops, monitors and CD players. Indium is a rare metal and it has not original mineral. The most important source of it is zinc minerals and regularly obtained from processing by-products of this minerals. The main problem of production of Indium is the simultaneous presence iron ions in the solution of dissolved minerals of zinc. In this project, extraction of Indium from acidic pregnant leaching solution of roasted zinc concentrate contained at less than... 

In this study, leaching of Sarcheshmeh Reverberatory Furnace Dust was investigated in the H2SO4-O3 media. Response surface methodology based on central composite face-centered design (RSM-CCF), was applied to optimize the operating parameters. The optimum conditions to obtain the main goal of maximum copper and minimum iron dissolution from dust were identified to be temperature of 30˚C, leaching time of 3hr, initial pH of 0.5, pulp density of 20% and ozone flow rate of 1g/h. The copper and iron concentrations of leaching solution were found to be 27.11 and 0.89983 g/L under the optimum conditions, respectively. The results showed that selective copper extraction from the dust could be... 

Uranium recovery from wastes produced in every stage of nuclear fuel cycle is very important from both the economic and environmental points of view. Zircon, zirconium-containing ore that is the input feed to Zirconium sponge production factories, contains considerable amounts of uranium compounds. The majority of this uranium will enter to the different waste streams of the plant. In this study, by analyzing the waste streams of the Zirconium Production Plant (ZPP) located at Isfahan, Iran, total mass balance of uranium in waste streams was identified. It was concluded that bottom residuals at furnaces of the chlorination unit is the primary uranium-containing waste stream. The preliminary... 

Waste of iron ore concentrate production plant of Chadormalu contains apatite mineral. The content of rare earths elements (REEs) in apatite concentrate of Chadormalu is about one percent. However, considering apatite deposite and production rate, extraction of REEs from apatite is one of valuable source for production of REEs. Lanthanum, cerium and neodymium which have most application amonge other REEs and have the highest frequency in the apatite. Due to their similar physical and chemical properties, it is difficult to separate individual rare earths from each other and the separation process are too complicated. In this study, in order to extract REEs from apatite, it was leached by... 

In this research copper oxide ores were dissolved under acidic condition. Chemical analysis (XRF) and X-Ray diffraction analysis (XRD) were used to identify the phases and determine the percentage and amount of the elements in the mineral. The results showed that the mineral contains 4.464% by weight of copper, which is malachite in mineral. The experimental design method (DOE) was used to dissolve concentrate by sulfurice acid. The parameters of temperature, time, acid concentration and solid to liquid ratio, as well as the interaction of these parameters on leaching and optimization of parameters were also done by response surface method (RSM). To determine the amount of copper dissolved,... 

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... 

The term “Rare Earth”, represents 17 metalic elements such as Sc, Y and Lanthanides wich have similar chemical properties. Lanthanides are a group of elements with atomic numbers of 57 to 71 that all of them exept Pm are present in nature. Rare earth elements are never concentrated in a special mine rock, but they could be found in various rocks and at very low concentrations. In the present study, apatite concentrate of Chadormalu was used for leaching and solvent extraction of Cerium, Lanthanum and Neodymium. After leaching step, its optimum conditions were found as follow: 30% nitric acid, 10 mins time and 10% for solid to liquid ratio. After finding optimum conditions, sufficient leach... 

In this research, Chadormalou apatite concentrate was dissolved by 40% nitric acid and a solid to liquid ratio of 0.4 at 70 ° C for 2 hours, and its rare earth elements were dissolved. Recovery percents for Cerum, Neodymium and Lanthanum were 62.4, 48.7 and 49.6, respectively. In the solvent extraction step, the effect of HQ concentration as extractant, pH, temperature and phase ratio on the concentration of the adsorbed elements in organic phase, extraction percentage, distribution ratio and separation factor of rare earths were investigated. Organic solutions containing HQ in the kerosene alone pricipitated after contacting with PLS solutions. In order to prevent HQ pricipitation in the... 

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... 

Considering the operation of the current nuclear reactors and the country's policy to achieve 10,000 megawatts of nuclear power in the horizon of 1420, in the coming years we will face a huge amount of radioactive waste, the majority of which is waste with low and intermediate levels of radioactivity (LILW). A large percentage of the radioactive waste production in Bushehr power plant is concentrated waste with a low and intermediate level of radioactivity (about 70% by volume). Due to the commisining of phase 2 and 3 of Bushehr power plant in the coming years and the increase in the radioactive waste production, proper planning should be done for waste management in order to reduce the... 

The foregoing note is a Ph.D. Thesis in Material Science and Engineering entitled "Leaching of hydrometallurgical treatment residue of zinc concentrate and Indium solvent extraction of solution". This research includes three stages of Roasting, Leaching, and solvent extraction. The scientific fundamentals and research background in all three domains have been studied. Investigations on the Roasting of zinc sulfide concentrate showed that in order to prevent the ingestion of indium into the zinc ferrit structure, the alkaline roasting process with 15% calcium oxide at 850 0C and 150 min prevented the ingression of 80% of the indium into the ferritic structure. The results of studies on the... 

In this study, the feasibility and optimization of recovering uranium from the tailings of the Meidok copper plant using heap leaching on a laboratory scale were investigated. The initial phase involved evaluating the agglomeration process and stabilizing particles. Parameters such as drum speed, acidity level, coarse-to-fine particle ratio, and residence time were examined and optimized. Following the optimization of the agglomeration process, column leaching tests (heap leaching method) with dimensions of 50 cm in height and 10 cm in diameter were performed. The selection of an appropriate and optimized heap leaching system considered parameters like solution injection rate, pH, and... 

In this research Feasibility of application of oxide compounds of bismuth, molybdenum and tin as biocide was studied. So some epoxy paints with different ratio of these compounds were formulated. Afterward some tests were performed to assessment paints properties such as leaching rate, antifouling activity, adhesion, corrosion resistance and impact resistance. Results of leaching rate test showed that increase in the ratio of bismuth oxide from 10% to 60%, led to increase leaching rate from 0.029mg.day-1.cm-2 to 0.126mg.day-1.cm-2. beside that Microscopic results showed proved that the ratio of bismuth oxide in the cured coating is 25% of the paint formulate. In similar ratio of biocides,...