Sharif Digital Repository

The sponge iron of the Hoganas process have a high metallization degree (93-96%) and its carbon content is about 0.1%. These characteristics are suitable for powder metallurgy but in order to use this DRI for steelmaking, it needs lower metallization degree and higher content of carbon. First, for using Hoganas sponge iron for steel production, 94% of metallization is adequate as some of iron is still in the form of FeO which its reduction in Electric Arc Furnace (EAF) cause better agitation in order to utilize heat transfer. Also, excess carbon content in the DRI can have many advantages other than preventing the sponge iron from re-oxidation. Some of the carbon can be in the form of Fe3C... 

In this study, the performance of Inconel 617 anode as an inert anode in aluminum electrolysis process was studied. To carry out the research, first, an electrolyte was produced using NaF, KF, AlF3 and Al2O3 with a molar ratio of sodium and potassium fluoride to aluminum fluoride of 1.33. Next, aluminum electrolysis cell was made using Inconel 617 anode and cathode and the aforementioned electrolyte. To evaluate the Inconel 617 anode, the performance of the electrolysis cell in different conditions of temperature, anode-cathode distance, and excess potential was investigated in a period of one hour. Using anode mass measurements, cell potential and current density and scanning electron... 

Much research has been done in the electromagnetic levitation process, but there is not any information about carrying out this process to refine steel continuously. In this study inclusion behavior of molten steel in contact with slag, in the presence of an electeomagnetic field, has been investigated. The steel sample, in an elliptical section, was levitated in an electromagnetic field, in a chamber containing slag consisting of CaF2-Al2O3-CaO, in order to achieve a continuous process, and changes in time, temperature and slag composition parameters in this process were studied. According to ASTM E45 standard, after performing metallographic process on melted samples, using light... 

In the present project, in order to be self-sufficient and optimal use of boron mines in Iran, a study entitled “The effect of process variables on the production of boric acid” has been conducted, This project has two main objectives: the first objective is the production of boric acid from boron sources and mines in Iran and the second objective is to analyze the effect of variables such as temperature, time, acid concentration, solid to liquid ratio and particle size on the purity of boric acid produced. And finally achieve the optimal conditions for the production of boric acid.In this study, boric acid was made from leaching hydrobracite (magnesium-calcium ore with boron) with sulfuric... 

Condensation from a gaseous phase is a common method for the fabrication of metallic nanoparticles. Electromagnetic induction furnaces are the most common equipment used for this method. Since the sample doesn’t touch any foreign object, this method is one of very few ways to synthesize ultrapure nanoparticles. However, a major setback of this method is its low production rate.One of the only workarounds to this issue is to increase the melt’s surface area so as to present a larger surface for evaporation. In the common setup for this furnace the molten sample takes on a spherical shape which unfortunately holds the lowest surface to volume ration of any shape. The endeavor in this study has... 

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, 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... 

In this study, silver nanoparticles (Ag NPs) with different morphologies were synthesize by physical and chemical methods. Spherical silver nanoparticles were synthesized by electro magnetic levitation melting approach, while silver nanoplates and nanorods were prepared by chemical reduction route. Ag NPs were then coated with thin porous silica shell. The dissolution behavior of synthesized Ag@SiO2 was investigated in PBS at 25, 37 and 55 °C. Spherical and triangular Ag@SiO2 were conjugated by Penicillin G molecules. The silver and penicillin contents of the synthesized nano-antibiotics were determined by ICP-OES and TGA analyses. The nanoparticles were characterized by X-ray diffraction... 

In this study, industrial steel (DIN 17135) underwent a new purification process with the aim of removing non-metallic inclusions and producing clean steel. Samples of steel were levitated in synthetic slag from the CaO-CaF2-Al2O3 system by an electromagnetic field. The effect of time, temperature and slag composition factors on the inclusions content of sample has been investigated. The images of the optical microscope were evaluated according to the ASTM E 45 standard, which according to the extracted results, the removal process was done to the desired extent. On the other hand, as the time and temperature of the process and the weight percentage of CaF2 increase, the number and size of... 

In this research the process of incomplete reduction of hematite low iron ore to magnetite in a fluidized bed reactor was investigated. Temperature, composition of reduction air, particle size, and stay time were investigated as effective parameters. In this way, temperatures of 560, 580, 600, 620 and 640 degrees of centigrade, input air with flows of 1.2, 1.3 and 1.4 l/s, particles size of 425-850 µm, 850 µm-1.4 mm, and 1.4-2 mm, stay times of 4, 8, 12, 16, and 20 min were used in this research. The reduced specimens were analyzed by XRD and chemical analysis. The results illustrated that increase of temperature, decrease of input air flow, decrease of particles size, and increase of stay... 

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... 

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... 

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,... 

In this report the important factors affecting the levitation melting of copper are discussed. Pure copper nanoparticles were synthesized by utilizing an Electromagnetic Levitation Melting Gas Condensation (ELM-GC) method. Pure bulk copper samples were melted and evaporated by electromagnetic levitation technique in an inert gas atmosphere in a silica tube. Copper nanoparticles were formed from ascending vapor by employing high purity argon and helium as carrier gases and cooling agents. The pressure of inert gas was changed in both helium and argon atmospheres to investigate on pressure’s effect. Particle size and morphology of the produced nanoparticles were studied by Field Emission... 

Electromagnetic levitation(EML) provides a process producing nanoparticles using gas condensation method. In gas condensation processes, vapor is produced by heating the sample then inert gas is applied to provide the inert atmosphere and also cool and condense the sample vapor into a nano powder to obtain a sample nanoparticle. In the EML method, rapidly alternating electromagnetic field induces eddy current in the conducting sample which will heat the sample. The current in the sample result in an induced magnetic field. Consequently, the sample droplet is heated and levitated simultaneously by an induction furnace as a generator. The sample temperature is dependent on parameters such as... 

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 study, four parameters were investigated including temperature, inlet flow rate, gas composition (oxygen) and particle size on the roasting of Bama company zinc sulfide concentrate in Fluidized bed reactor. Initially, primary sample was heated in electric furnace at 125℃ for 24 hours until the moisture content dried. Then roasting operation was done at 700 and 900℃. The operation was carried out on three range of particle size including 300-500, 500-700 and 700-1000 microns and flow rate was greater than the minimum flow rate of Fluencing. To investigate the effect of flow rate and gas composition input, 500-700 micron particle size range was selected. The effect of 155, 172 and 188... 

In this study effect of air flow rate, particle size and oxygen excess on roasting of copper concentrate in a fluidized bed reactor were investigated. Copper concentrate in this work was from sarcheshme copper mine. For determination of the weight percentage of remaining sulfur, calcins were analyzed by XRD. The effect of air flow rate was studied at 211,250 and 312 lit/min. The results indicate that an increase in air flow rate led to a decrease in amount of sulfur in the calcin. For study the effect of oxygen excess roasting were done with 20,21 and 23 volume percent of oxygen and the results were the same as the effect of air flow rate. For study the effect of particle size, roasting were... 

In this study, the effect of iron ore concentrate morphology on green pellet quality was studied. In order to produce concentrate with different morphology using ball mill, ball charge (20-40 %V), grinding time (30-50 min) and ball distribution (15 mm, 23 mm, 15+23 mm) was varied. It was deduced that increasing grinding time and ball charge would result in reduction of D80 but would increase Blaine number. The interaction parameters of ball distribution-grinding time and ball distribution-ball charge had significant effect on Blaine and D80. It was also observed that mixed level of ball distribution would lead to higher Blaine numbers. The equation obtained by CCD was verified by the... 

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...