Department of Mineral Processing (2014 - Present)
Chemistry
Mineral Processing, Melbourne, Melbourne, Australia
Mineral Processing
Mining, Tehran, Tehran, Iran
Mining
Mining, Amir Kabir, Tehran, Iran
Research field: Precious Metals Electrorefining
Expert: bahram Pashang
Phone: 00982182884962
Address:
Process Mineralogist and Hydro metallurgist with 15 years of academic and industrial experience in Iran, Australia and Turkey Education: PhD of Mineral Processing Engineering, 2014- University of Melbourne-Australia M.Sc of Mineral Processing- 2007- Tehran University -Iran B.Sc of Mining Engineering - 2003- Amir Kabir University-Iran
The abandoned lead mine of Shahroud Gholleh Kaftaran at 4km northeast of the Chah Mousa mine contains significant resource of processing tailings left in the area. These tailings could be exploited with significant resource of over 50,000 tons with a copper oxide content of 0.95%. In this study, copper recovery from Gholleh Kaftaran mine processing tailings has been studied by agitated leaching and iron cementation methods. In the leaching experiments, pH and particle size had the greatest effect on copper dissolution, respectively, while solid percent and time had lower effect. In the coarser particles, the pH of the solution is not as effective as finer particle sizes as liberation and exposure of the malachite play the key role, here. Th
The interaction of gold cyanide complex with elemental sulphur and all metastable sulphur species has been studied using Density Functional Theory (DFT). The elemental sulphur and sulphide species formed during pre-treatment of refractory gold ores or dissolution of sulphide minerals form a series of metastable species including hydrosulphide, polysulphide, thionates, sulphite and finally sulphates which are known to have a detrimental effect on gold cyanidation. Previous researchers have attributed this effect mainly to passivation of the gold surface. However, interaction of dissolved aurocyanide with sulphur species has received almost no attention. Here, DFT molecular modelling has been used for the first time to describe the interactio
Fine particles of pyrite are not recovered completely by magnetic separators in presence of iron ores such as magnetite and hematite. Reverse flotation is an effective method to reduce sulfur from magnetic separators concentrate. The aim of this study is to investigate the effect of operational variables on flotation column performance in desulphurization process from iron concentrate and to optimize operational conditions for the sake of achieving the maximum sulfur recovery with the minimum iron waste. To do so, by conducting 45 tests, based on a central composite design (CCD), the effect of important operational factors including gas flow rate, froth depth, slurry solids percent, frother/collector dosage and pH was considered. The iron o
Nugget effect is a common feature of many vein-style gold deposits. This style of mineralization results in complication in many exploitation stages including resource and average grade estimation, representative sample selection, ore characterization as well as processing. Accurate and reliable ore characterization is a vital stage in any mineral processing project. Ore characterization in high nugget effect gold ores is so complex due to uncertainties associated with representativity of the selected sample. The main challenge is to provide a representative sample for identification of each process mineralogy parameter such as average grade, liberation, grinding size, mineral association, floatability, etc. Here, different protocols are co
The role of sulfur species in the passivation of gold surface in cyanide and thiosulfate solutions was investigated using density functional theory (DFT). The interaction energy between various sulfur complexes as well as deposited sulfur allotropes with the gold surface were computed and the contribution of each specie to the formation of a passivated layer were compared. For this purpose, a new parameter was introduced to explain and understand the tendency of each sulfur complex to interact with the gold surface from a molecular point of view. It was observed that the ratio of the hydration to the binding energy (H/B) of each sulfur specie can be well correlated with the calculated interaction energy with the gold surface. This parameter
In this study, the desulphurization of iron ore concentrate using reverse flotation was investigated. In this paper first, behavior of the flotation of both pure – pyrite and iron oxides-pyrite with xanthate has been examined based on micro-flotation results and zeta-potential measurements. Then, an effort has been made to investigate the effect of pH, chemical reagent dosages, impeller speed, pulp density, flotation time and conditioning time parameters on desulphurization of actual iron ore concentrate using lab-scale mechanical flotation cell. Results of zeta-potential measurements displayed that iso-electric points (IEP) for pure and iron oxides-pyrite were around pH 7 and 8, respectively. Based on the micro-flotation results, the rec
The flotation froth surface appearance includes remarkable information, which can be employed as a helpful index for the qualitative evaluation of the process efficiency. Image analysis is a practical technology for the sake of achieving process related information that can be employed in expert controllers in order to amend flotation performance. In this paper, the intelligent modelling of relationship between froth characteristics and the metallurgical performance in a pilot column flotation of iron ore was established. Column flotation tests were carried out at a wide range of operating conditions and the froth features along with the metallurgical performances were specified for each run. The artificial intelligence models suggested for
In the last few decades, many studies have been performed with the main hope of utilizing imaging methods so as to detect static (bubble size and shape, color, texture) and dynamic (velocity and stability) features of froth that involve crucial information about the process state in order to assess and monitor the performance of flotation process. Although several types of flotation automated control system problems are being successfully solved using the various techniques of features extraction from froth images, there are still a number of unresolved subjects and obstacles. Hence, a suitable review of these methods is needed. After reviewing the technical aspects of froth images structural features in part 1 of this two-part review paper
The content of sulfur in iron ore concentrate is the major problem of steel making industries. In this regard, the reverse flotation operation is used to reduce the amount of sulfur of the final concentrate. Recently, the substitution of mechanical flotation cells with flotation columns for the sake of impurities removal has been highly taken into consideration. The purpose of this study is comparing the performance of mechanical and column cells in desulphurization of Gole Gohar iron ore complex magnetic separators concentrate. Using column flotation in an optimal condition led to the remarkable reduction of sulfur so that the final concentrate with the sulfur grade lower than 0. 1% and iron recovery over 98% was obtained. The results comp
The speciation of copper and gold cyanide complexes was investigated using Density Functional Theory (DFT) in order to understand the behaviour of these complexes in aqueous solutions. To represent the local environment, two methods of implicit (COSMO) and explicit water molecules were utilized and the results were compared to evaluate their capability. The hydration state of the species, stability constants, cluster formation, interaction of different species and finally the gold leaching character of copper cyanide complexes were investigated in details. The solvation energy of Au (CN) 2−, Cu (CN) 2−, Cu (CN) 3− 2 and Cu (CN) 4− 3 were calculated as− 41.1,− 42.5,− 98.1 and− 168.7 kcal? mol− 1 with 4, 4, 6 and 8 water mol
This experimental study investigates the influence of H+ and Cl− ions on the leaching procedure of the iron ore tailings (IOT) using different lixiviants including various ratios of H2SO4/NaCl, and HCl. By using HYDRA/Spana software, the formed species of iron were identified as FeCl3, Fe(SO4)2− when using 5 M H2SO4/2 M NaCl, and FeCl3, FeCl2+ when utilizing 5 M HCl as leaching lixiviant at 85 ?C with significant iron recovery (>85%) within 6 h. However, the combination of 5 M H2SO4/2 M NaCl was more advantageous for the leaching process due mainly to the increased activity of H+, as well as precipitated Ca+2 ions as gypsum. Eventually, for modelling purposes, the iron leaching process was found to fit well with the shrink
In this paper, beneficiation studies were carried out on a low-grade tungsten-bearing scheelite from Nezam Abad ore with total WO3 grade of 0.11%. Mineralogical studies showed that scheelite is mainly distributed in the ore and gangue minerals include Quartz and Tourmaline. Liberation degree (d80) of tungsten- bearing scheelite is achieved around particles size 150 μm. Gravity concentration, magnetic and flotation methods were conducted by using experimental designs including fractional factorial and response surface methodology. Gravity concentration results indicated that jig separator could not be able to improve tungsten grade in size fraction +600–1750 μm; however, shaking table increased feed grade up to 27.05% with
Flotation performance is expected to be affected by froth characteristics due to the changes in the operating conditions. However, very little study has been undertaken to investigate how froth behavior responds to the flotation variables. This study presents an experimental program performed to investigate the effects of flotation variables including gas flow rate, froth depth, slurry solids percent, frother/collector dosage, and pH on the froth features such as bubble size, froth velocity, froth color and froth stability during desulfurization of an iron ore. These parameters were varied using a central composite design (CCD). Image analysis methods have been developed and employed successfully to characterize the froth features. Results
It is now generally accepted that froth appearance is a good indicative of the flotation operation conditions. Image analysis technology now offers a viable means of monitoring and control of the flotation process. In this paper، the relationship between the operational variables (ie gas flow rate، froth depth، slurry solids%، frother/collector dosage and pH) and the froth features (ie bubble size، froth velocity، froth colour and froth stability) in the column flotation was discussed during desulfurization of an iron ore using response surface methodology. Image analysis techniques have been developed and used successfully to characterize froth. Results of the CCD experiments showed that the flotation variables have different effects
This study demonstrates the computation of the structures and properties of different gold complexes with significant relativistic effects including gold chloro–hydroxy species, gold thiosulphate and thiourea, using density functional theory (DFT). Simulations using the COSMO (COnductor-like Screening Model) description of solvation for systems with different complexants can effectively represent the surrounding media and produce results comparable with the limited available experimental data. In gold chloride systems, the stability constant for each gold (III) chloro–hydroxy species was calculated using the DFT methodology for the first time, showing excellent correlation with experimental results. The best results were obtained based
This study investigates the effect of different grinding processes on the preg-robbing behavior of quartz. The adsorption of gold onto the quartz surface in a chloride medium is determined after grinding in a ball mill with steel media, and in a ring mill. The mechanical activation of the ground quartz is significantly influenced by the type of mechanical action in the mill; the compression–shear action of the ring mill seems to be more effective than the impact–attrition action in a ball mill. As a result, the grinding limit is lower in the ball mill, and agglomeration is not significant after the grinding limit. Grinding yields significant propensity towards adsorption of gold chloride complexes from solution, firstly due to an increa
Silicates are not generally regarded as problematic in gold metallurgy, because gold encapsulated within silicate minerals is in most cases easily liberated and separated from silicates by common gravity concentration, flotation or leaching techniques. However, a series of counterintuitive observations in the extraction of gold from silicate containing ores has raised the need for investigation of the role of silicates in gold processing. This project addresses the problems associated with silicates during the hydrometallurgical processing of gold and aims to develop a fundamentally based understanding of the interaction between aqueous gold ligands and silicates. The occurrence of silicates in gold ores and their effect in different uni
Mechanical activation of the 2:1 layer lattice aluminosilicate pyrophyllite is investigated, with particular regard to the implications of this process for gold preg-robbing behaviour. Short-term grinding in a high energy laboratory ring mill increases the adsorption of gold by pyrophyllite in an acidic chloride medium, which would be problematic in the operation of a hydrometallurgical process. However, prolonged grinding (30?minutes or more) inhibits the sorption of gold anions onto the surface of pyrophyllite, reducing the extent of gold losses from solution. Analysis of surface chemistry and structure of ground pyrophyllite reveals significant distortion of the mineral by grinding. The dehydration and dehydroxylation of pyrophyllite dur
The effect of high-energy milling on the surface properties of quartz is examined with regard to its preg-robbing behavior towards gold. A standard ring mill is used to process dry quartz samples, and the changes in the morphology of the particles, structural deformations and surface chemistry are investigated to explain the increased preg-robbing ability of quartz in acidic chloride solutions. The transition from fine grinding to mechanochemical activation of quartz can be observed from changes in the morphology of the particles, as well as the types of structural deformations. The transition occurs between 1 and 5 min of grinding in the mill used, corresponding to particle sizes around 0.55 μm. Structural studies differentiate two stages
The mechanism of adsorption and reduction of the gold chloride complex on silicate minerals is investigated. Gold chloride, supplied as HAuCl 4 solution, is rapidly adsorbed on the silicate surfaces, the Au (III) is reduced to metallic gold, and gold particles grow on the surface. SEM images show agglomerates of gold unevenly distributed on the surface of the silicates, including in some areas forming agglomerates, especially on quartz and feldspar. Silica gel forms via dissolution of silicates in acidic conditions and also has strong adsorption/reduction potential for gold. A mechanism for the adsorption and reduction is proposed, involving ligand substitution between gold chloride and OH groups on defect sites in silicate surfaces. Conseq
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