Sharif Digital Repository

In the present work, aluminothermic reduction of vanadium pentoxide have been used to produce aluminium vanadium alloys. The effect of addition of lime and excess aluminium on the produced alloy was studied. The experiments were carried out in air and in argon. The alloys microstructure were analyzed bu light and scanning electron microscopy. Other methods such as XRD, XRF, ICP, AAS and titration were employed to analyzed the alloy and the slag. It was found that the addition of lime and excess aluminium increase the yield of the alloy. Vanadium recovery was not affected by the atmosphere used.
 

Nd-Fe-B alloys as permanent magnets are used in the components of the computer, sensors, medical equipments and etc. Two main methods which used for making these alloys, are calciothermic reduction process and fused salt electrolysis technique. In this study, a new affordable process for producing Fe-Nd alloys have been suggested.In this research, aluminothermic reduction and co-reduction processes were used to make a Pb-Nd alloy from neodymium oxide (Nd2O3) and Lead Oxide (PbO). Then by using liquid-liquid extraction at high temperature, Fe-Nd alloy was produced. Experiments were performed at temperature of about 1600°C and in the air atmosphere. Different weight ratios were also tried. The... 

To obtain solutions containing Titanium, leaching of Ilmenite Concentrate of Kahnooj and its Slag by Sulfuric Acid 98% in various Conditions are Studied. Screening tests by Fractional Factorial method were designed, at this step effects of Temperature, Acid Concentration, Particle Size, Solid to liquid Ratio, Time and Stirring Speed were investigated and It was Concluded that Temperature, Time, Acid Concentration and Particle Size were the effective Parameters in both leaching process of Ilmenite and Slag. The Temperature, Time and Acid concentration had positive effect, whereas the Particle Size had negative effect. After screening step, effective parameters were optimized by Rotatable... 

Sponge Iron production is conducted in various methods that one of them is using coal as a reduction agent. Hoganas process is a different coal-based method that has not been investigated in details. Therefore, the heat transfer method in the system is one of the basic steps to a better recognition of this process (with special Hoganas charging). The present paper investigates the temperature distribution method in the Hoganas cylinder through a numerical model using finite elements. The effects of different parameters, namely preheating and porosity were studied on ceramic crucible made from silicon carbide and it was observed that the consumption energy decreases with the increase of... 

In This project high purity Zinc (Zn) Nanoparticles were synthesized using Electromagnetic Levitation Melting Gas Condensation method. In this method the designed coil plays an important role on melting and suspension of the material and our design was costumed specifically for zinc nanoparticles. For each batch of synthesized Zn nanoparticles, 1.5 gr zinc platelet was levitated in the costumed coil and the effect of different parameters on the size and distribution of nanoparticles, was investigated including in- different cooling gas (He, N2 and Argon), gas flow rate, and the pressure inside the chamber. Inert gas was used to cool supersaturated vapor above the molten droplet and eliminate... 

The purpose of this project is to survey the created kind of inclusion in super alloyed based nickel. primarily, for this matter for the preparing of super alloyed based nickel, the vacuum induction melting furnace has been designed and built , then for surveying the kind of inclusion the effective parameters such as temperature , timing and material of crucible has been considered accordingly , the material of crucibles was considered based on mud-clay- graphitic- pure graphitic- aluminum- zirconium. From the obtained analysis samples of SEM has been distinguished which, with increasing of the temperature and the time ,the percentage of impurity will go up in super- alloyed and the... 

Different methods can be used to produce reduction gas. One example is using coal. But today there’s a tendency to use natural gas. One way of transforming natural gas to reduction gas is to burn it with gases produced by combustion, such as or vapor; usually a catalyst is used in this method. Another method is burning natural gas directly with oxygen or air. The recent method is of benefit especially in Iran, because of available natural gas resources and avoiding catalyst problems. Designing a burner for this purpose is an important step in reaching this goal. In this project such a burner is designed and manufactured. The burner manufactured in this project burns natural gas with... 

Sialons are materials which crystallize in four elements system (Si-Al-O-N). These materials have been widely observed by researchers because of their suitable properties like: high toughness and strength in high temperatures, high resistance to corrosion and stability in thermal shock. Because of these properties,Sialons are anti erosion materials. In this research, by controling the situations, mullite has been synthesized by sol-gel procedure. Then the powder has been ground by ballmill for 12 hours and by spex for 30 minutes. Then the produced powder was mixed with distinct amount of graphite and nano silica and was nitrided in the furnace at 1500 ̊C and was heated for 5 hours. Also... 

Electromagnetic levitation gas condensation (ELGC) method was used to synthesize silver nanoparticles. Silver droplets were melted and levitated stably at about 1130 °C with appropriate flat coils in a 10 mm OD silica tube. High purity argon, nitrogen and helium were employed as carrier gases and cooling media. Morphology and particle size of the products were investigated by scanning and transmission electron microscopy (SEM and TEM), X-ray diffraction (XRD) energy dispersive X-ray analysis (EDAX) and dynamic light scattering (DLS). The DLS, SEM and TEM studies demonstrated narrow size distribution of spherical shape Ag nanoparticles with particle size of about 60, 45 and 35 nm synthesized... 

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... 

Silver nanopowder is of great importance for various medical and industrial applications. Due to the significance of the solubility of silver nanoparticles in these applications as well as the high impact of the nanophysical morphology of the powder on their solubility, we prepared nanoparticles with plate morphology by the chemical reduction of silver nitrate in a soluble phase. Then we measure its solubility in a phosphate buffer salt, which greatly resembles the human blood chemically. The size and shape of the resulting nanosilver powder and also the use of non-toxic materials in their synthesis are important factors in the production of nanosilver powder.We confirmed the successful... 

Due to the expanding trend of using induction furnaces in Iran, the production of sponge iron at a smaller scale by Midrex method has become important. Since induction furnaces cannot benefit from the oxygen blower and foam slag like arc furnaces, the induction furnace charge should be of a higher quality. In addition, as the oxidation conditions in induction furnace are higher in comparison to arc furnaces, re-oxidation control of the induction furnace is essential. Making briquettes is one of the processes, which reduces re-oxidation during melting and since the briquette remains floated on the melt until complete melting, the lower level of briquette's contact with ambient atmosphere and... 

In this work feasibility of concentrating zinc carbonate ore from Anguran mine by froth flotation process has been studied. Potasium Amyl Xhantate and Oleic Acid have been studied as possible collectors. The initial tests indicate that oleic acid might be a better collector. Experimental were conducted to determined important factors and to optimize the process by careful control of the pulp chemical composition and flotation variables. A concentrate containing 24.9% zinc has been attained. The recovery of zinc in the concentrate is 76.1%.
 

Samples of INCONEL 718 were levitated and melted in a slag by the application of an electromagnetic field. The effects of temperature, time and slag composition on the inclusion content of the samples were studied thoroughly. Samples were compared with the original alloy to study the effect of the process on inclusions. Size, shape and chemical composition of remaining nonmetallic inclusions were investigated. The samples were prepared by Standard Guide for Preparing and Evaluating Specimens for Automatic Inclusion Assessment of Steel (ASTM E 768-99) method and the results were reported by means of the Standard Test Methods for Determining the Inclusion Content of Steel (ASTM E 45-97).... 

In this study, the recovery mechanism of nickel oxide by carbon dissolved in molten iron with the study of reaction kinetics were investigated. Nickel oxide pellets into molten iron containing graphite were added in the neutral atmosphere and the release of CO gas as a function of reaction time was measured until the end. The volume of gas produced at different times shows the number of moles of Ni metal was revived. Reaction by a) the following decomposition reaction under 1475 °C ; and b) carbon diffusion rate at temperatures over ° C1475 is controlled. The main reaction mechanism in order to a) decomposition of NiO; b) penetration of oxygen atoms in the melt, and c) reaction between... 

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... 

In this study, the effect of two main parameters, time and temperature, were investigated in the roasting process of zinc sulfide of Bafgh’s mine, and kinetics and the mechanism of the roasting reaction were examined, too. The oxidation process was performed in a muffle furnace in the presence of the oxygen of air atmosphere. The raw powder material (with the particle size of 74-250 micron) was poured in Alumina crucibles. The roasting process was run in eight temperatures of 650, 700, 750, 800, 850, 900, 950 and 1000 ◦C. Oxidation percent was calculated in six times of 5, 10, 15, 30, 45 and 60 minutes. The experiments were designed in a way that the effect of each parameter could be... 

This research has studied the kinetic and mechanism of partial reduction of hematite to magnetite via carbon monoxide gas. In addition, temperature and partial pressure of CO gas as two main parameters which influence the rate of the reduction process has been studied. In order to investigate the change in mass during the reaction, thermogravimetric analysis (TGA) has been applied and in order to evaluate the effect of the temperature and partial pressure of CO on the rate of the reduction, three different temperatures and two different ratios of CO/CO2 has been experimented. Three isothermal analysis in 390°C, 440°C, and 490°C in pure CO atmosphere and two isothermal analysis in 550°C with... 

Hoganas is a gas based process which is more than a hundred years old. In this research, studying parameters affecting the quality of sponge iron like temperature, time, particle size, type of reductant, type and dimension of crucible were discussed. Groups of particle size was 0-150,150-500,500-1000microns and temperature range was 900, 950, 1000, 1100, 1150°C. Time of tests was between 2 to 30 hours.at 1000 °C and 10 hours maximum metallization degree was 94.76.while at 1100 °C and 5hours better metallization degree was achieved. at 1000 °C and 5 h, particles with 500-1000micron size had better result than other groups.at higher temperature effect of particle size was gradually decreased... 

In this work, polyvinylidene difluoride (PVDF) as a ferroelectric polymer, polyaniline (PANI) and polypyrrole (PPy) as conductive polymer additives are used to fabricate high performance mesoporous CH3NH3PbI3-xClx mixed-halide perovskite solar cells in a sequential deposition method. Using polymer additives in perovskite precursor solution leads to modification of perovskite layer morphology by changing nucleation and growth of perovskite grains. Besides, conductive polymer additives in perovskite layer help to more charge carrier transfer. Power conversion efficiency has been enhanced from 10.40 % to 16.51% and to 13.21 % in ambient atmosphere in the presence of 1.0 wt. % of PVDF and PPy...