Sharif Digital Repository

Density currents are occurred as a result of the intrusion of a dense fluid into a fluid with a different density. Density difference is the main agent of current’s movement. These currents are observed in nature numerously and they are one of the main reasons of the erosion and transportation of deposition in oceans, seas and rivers. Investigation of these currents is of great importance especially in dams’ reservoir as major cause of deposition and reduction of reservoir’s efficency. Density differences are typically caused by the difference in temperature, existence of solution or insoluble material and suspended solids. In this work, density current is studied experimentally. Density... 

MP210 alloy is a member of multiphase family alloys, a class of wrought nickel-cobalt base alloys extensively used in high-quality applications including aerospace fasteners, gas turbine engines and petrochemical industry. Very limited information can be found in the literature about the microstructure and phase transformations of this alloy. The aim of this work is characterizing the aging response of the material and identifying the major strengthening phases precipitated in different range of temperatures and also studying the static recrystallization behavior of this alloy. The effect of age-hardening heat-treatment on the microstructure of MP210 superalloy was investigated using... 

In this study, the effect of submerged vanes on the bed scouring and deposition pattern at a 90̊ open-channel junction was investigated. First, the bed formation without submerged vanes were studied under the effect of hydraulic variables like the discharge ratio of tributary to main channel and the ratio of mean approach velocity to the threshold velocity. The results show that scour holes enlarge with time while they move towards the downstream and the outer wall in the main channel. Also, by increasing the ratio of mean approach velocity to the threshold velocity about 0.5, the maximum scour depth occurred at the downstream junction corner with time. In the second stage, the proper vane... 

Density currents, caused by the intrusion of dense fluids under lighter ambient fluids, frequently occur in both natural and industrial situations. As a result of the density differences, the driving force can arise from soluble substances, temperature differences, etc. If the driving force comes from suspended particles including silt and mud, the currents are called turbidity currents. Due to the variation in concentration and the consequent driving force along the flow path, turbidity currents are significantly more complicated than saline currents. These currents play the most important role in sedimentation in lakes, seas and oceans. In addition, turbidity currents are the main factor... 

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... 

Management and reservation of mine tailings are among the most important problems in today’s engineering. Among the different kinds of mine tailings, wet tailings are of the most critical ones due to their slurry shape. In addition to their different form of settlement than normal kinds of soil, they can easily transfer the pollutants through their base to the adjacent areas. Therefore, investigation of their sedimentation and consolidation processes is necessary. In this thesis, it has been tried to program a code according to the literature, in order to simulate the sedimentation and consolidation process of wet tailings. The mathematical method that has been used in the thesis for solving... 

In this research, uranium is leached from pHospHate ore of Sheikh Habil region by leaching operation using leaching agent (sulfuric acid) along with production of pHospHoric acid. In the following, the production of yellow cake from the produced liqueur solution (pHospHoric acid) by solvent extraction process is also mentioned. PHospHate ore contains a large amount of calcite and dolomite, which removal of these annoying elements by wet, dry and acid washing methods is the key to success in the production of pHospHoric acid. For this purpose, in the wet method of a flotation system, the dry method of heat furnace and in the acid washing method, various organic and inorganic acids were used... 

The reduction of the effective permeability of the reservoir rock in the production area due to various factors is called formation damage. Formation damage is always one of the topics discussed in petroleum engineering. Among the primary and important cases that lead to damage to the formation are the filtration of drilling mud into the production area and the deposition of colloidal particles inside the porous rock during the drilling operation. The length of the productive zone in contact with the drilling fluid usually reaches several hundred feet in Iranian formations. In this study, the aim is to more accurately estimate the amount of permeability reduction caused by the penetration of... 

The dewatering processes within Tailings Storage Facilities (TSFs) involve a complex interplay of sedimentation, self-weight consolidation, and desiccation driven by surface evaporation of tailings slurry. Effective management of TSFs presents significant challenges in the field of mining engineering, such as implementing sustainable disposal practices to mitigate environmental pollution, preventing soil contamination from leakage, and ensuring the structural stability of TSFs under static and seismic conditions. Therefore, accurate modeling of dewatering behavior in wet tailings within TSFs is crucial for assessing TSF volume, estimating the lifespan of existing TSFs, determining optimal...