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acidic-leaching
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Leaching of an oxide gold ore with chloride/hypochlorite solutions
, Article International Journal of Mineral Processing ; Volume 82, Issue 4 , 2007 , Pages 178-186 ; 03017516 (ISSN) ; Sharif University of Technology
2007
Abstract
An oxide gold ore was subjected to chloride/hypochlorite leaching at room temperature. The effects of three factors, including Ca(OCl)2 vs. NaOCl, OCl- concentration, and HCl concentration on gold leaching performance were investigated. Due to formation of CaOCl+ complex in solution and hence less reactivity, calcium hypochlorite produces a sluggish gold leaching kinetics, taking twice the time (46 h) to achieve maximum gold recovery of 58% compared to sodium hypochlorite. 10 g/L of total initial hypochlorite species in solution produces reasonable gold recoveries. The amount of added HCl and hence the initial pH was found to have a major effect on gold leaching kinetics and maximum gold...
The effects of a hydrochloric acid pre-treatment on the physicochemical properties and pozzolanic performance of rice husk ash
, Article Cement and Concrete Composites ; Volume 39 , 2013 , Pages 131-140 ; 09589465 (ISSN) ; Khaloo, A. R ; Rajabipour, F ; Sharif University of Technology
2013
Abstract
This paper investigates the effects of acid normality (0.01-6 N HCl) and combustion retention time (0.25- 16 hours) on the pozzolanic properties of pre-combustion acid-treated rice husk ash. The pozzolanic reactivity was quantified by adding ground ash to saturated Ca(OH)2 solutions and monitoring the time-dependent electrical conductivity and pH of the solutions. Also, the strength activity of ashes from different processes was measured by testing the compressive strength of mortars. It was observed that acid treatment results in ashes with higher SiO2 content, lower alkali and unburned carbon content, better grindability, and smaller particle size, in comparison with ash from non-acid...
Optimization and Kinetics of the Leaching of Titanium from Ilmenite and its Slag
, M.Sc. Thesis Sharif University of Technology ; Halali, Mohammad (Supervisor)
Abstract
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...
Roduction of Solar Grade Silicon by Thermal Refining of Industrial Grade Silicon
, M.Sc. Thesis Sharif University of Technology ; Yoozbashizadeh, Hossein (Supervisor)
Abstract
The photovoltaic (PV) industry is in rapid growth and a large supply of PV feedstock materials must be provided to maintain this growth. Since silicon is still the dominant material for the fabrication of solar cells, low-cost solar-grade silicon (SoG-Si) feedstock is demanded. The most cost-effective and direct approach for producing SoG-Si is to purify and upgrade metallurgical-grade silicon. The major impurities in silicon are Al, Fe and Ca. other impurities present are Cu, Ti , Zn, Ni, Cr, Mn, Cd, B and P. In this study The effects of the acid leaching process parameters, including the particle size of silicon, the acid type (HCl, HNO3, H2SO4, and their combination), tmepreture and the...
Leaching of Titanium-bearing Concentrate of Solid-state Reduction of Titanomagnetite Ores
, M.Sc. Thesis Sharif University of Technology ; Askari, Masoud (Supervisor)
Abstract
Some of the low-grade titanium resources which are located in the country are titanomagnetite placer deposits. In current study, beneficiation of titanium-bearing concentrate of a placer deposit containing 6.13wt.% TiO2 was investigated by acidic leaching in order to remove impurities. To beneficiate the concentrate, based on the optimum conditions obtained in previous studies, solid-state reduction, magnetic separation, and calcination of non-magnetic product were performed. Afterwards, by studying temperature, time, acid concentration and L:S ratio, the final product was leached under optimal conditions were as follows: H2SO4 concentration of 15wt.%, L:S ratio of 20:1 (mL:g), reaction...
, M.Sc. Thesis Sharif University of Technology ; Yoozbashizadeh, Hossein (Supervisor) ; Moradkhani, Davoud (Supervisor)
Abstract
The environmental pollutions besides wasting the valuable materials as two main challenges in pyrometallurgical processes have brought up the tendency towards the hydrometallurgical processes. In the present study, the recovery of germanium from leaching residues of zinc plant has been investigated. Firstly, the required tests for concentrating the residues through washing of the zinc were designed by taguchi method, and optimum condition for maximum leaching of zinc accompanied by minimum desolution of germanium were obtained. The sulfuric acid concentration, time, termperature of reaction, solid to liquid ratio and rate of stirring are the parameters studied in this research. The obtained...