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Chalcopyrite is the main copper-bearing ore and is refractory to oxidative leaching. There are many investigations about optimization of copper extraction from this mineral but most of them are energy intensive and environmental threatening. Alternatively, ozone at low concentration is an efficient reagent for high recovery of copper from chalcopyrite, which is also ecofriendly. This paper presents a comprehensive investigation on process optimization for both copper and iron extraction from chalcopyrite using ozone. The following variables were tested during 48-h leaching periods: temperature, ferric sulfate, ozone, and sulfuric acid concentrations, solid/liquid ratio, and leaching time. Ozone leaching recovered 100% of the copper from chalcopyrite at 25 °C without addition of ferric. The overall reaction kinetics followed the shrinking core model by mixed control of diffusion through the product layer and chemical reactions. The proposed leaching mechanism was verified via various characterization techniques. Green chemistry metrics were evaluated, and the optimized process was demonstrated to be environmentally attractive. Ozone leaching appears to have strong potential as a “green” and technically feasible method to leach copper from chalcopyrite.
Jingxiu Wang; Fariborz Faraji; Ahmad Ghahreman. Evaluation of ozone as an efficient and sustainable reagent for chalcopyrite leaching: Process optimization and oxidative mechanism. Journal of Industrial and Engineering Chemistry 2021, 1 .
AMA StyleJingxiu Wang, Fariborz Faraji, Ahmad Ghahreman. Evaluation of ozone as an efficient and sustainable reagent for chalcopyrite leaching: Process optimization and oxidative mechanism. Journal of Industrial and Engineering Chemistry. 2021; ():1.
Chicago/Turabian StyleJingxiu Wang; Fariborz Faraji; Ahmad Ghahreman. 2021. "Evaluation of ozone as an efficient and sustainable reagent for chalcopyrite leaching: Process optimization and oxidative mechanism." Journal of Industrial and Engineering Chemistry , no. : 1.
A novel and sustainable technology to recover gold from thiosulfate medium using ionic liquids, i.e., Cyphos IL 101 (Cy IL 101) and Cyphos IL 102 (Cy IL 102) diluted in toluene, has been developed. Gold was extracted into the ionic liquid phase as [{P66614+}3{Au(S2O3)23–}] and stripped using NaCl solution. The recyclability of ionic liquids has shown promising recirculation of the solvents for the extraction of gold from thiosulfate medium. Gold was quantitatively extracted from 0.2 mol/L sodium thiosulfate initially containing 10 mg/L gold at pH = 9.0 with 1.25 mmol/L ionic liquid (Cy IL 101 or Cy IL 102) in one stage at A/O = 2, whereas total gold stripping with 1.5 mol/L NaCl also needed one stage at A/O = 1. Using a high A/O ratio in the extraction stage (A/O = 10) and low (A/O = 1/10) in the stripping stage confirmed the economic and environmental viability of the process. The results revealed that Cy IL 101 presents slightly better behavior toward gold recovery than Cy IL 102 and is a viable and promising alternative to recover gold from the thiosulfate medium on a pilot scale. The overall study confirmed the suitability of the developed scheme for industrial application to provide economic and environmental benefits.
Harshit Mahandra; Fariborz Faraji; Ahmad Ghahreman. Novel Extraction Process for Gold Recovery from Thiosulfate Solution Using Phosphonium Ionic Liquids. ACS Sustainable Chemistry & Engineering 2021, 9, 8179 -8185.
AMA StyleHarshit Mahandra, Fariborz Faraji, Ahmad Ghahreman. Novel Extraction Process for Gold Recovery from Thiosulfate Solution Using Phosphonium Ionic Liquids. ACS Sustainable Chemistry & Engineering. 2021; 9 (24):8179-8185.
Chicago/Turabian StyleHarshit Mahandra; Fariborz Faraji; Ahmad Ghahreman. 2021. "Novel Extraction Process for Gold Recovery from Thiosulfate Solution Using Phosphonium Ionic Liquids." ACS Sustainable Chemistry & Engineering 9, no. 24: 8179-8185.
Gold recovery from limited global resources has gained increasing attention due to a growing demand for gold and heightened social awareness of the high toxicity and the environmental threat of traditional cyanidation. This has led to the development of biomining methods to extract gold from low-grade ores and a variety of wastes using microbes to generate the required reagents. One such method, biocyanidation, has the potential to be an environmentally friendly technique for gold recovery from ore and secondary resources. This review quantifies the limited global gold resources, presents the gold leaching technologies, and describes the biocyanidation process, including the properties of commonly used cyanogenic bacteria and the influencing factors. Methods to measure free biogenic cyanide are summarized, with a focus on the silver nitrate method with potentiometric end-point titration. Finally, biocyanidation is systematically and comprehensively analyzed in the context of commercial and technical limitations imposed by low-grade gold reserves that are infeasible for commercialization, and recommendations for improvements to the process are suggested. This review provides insights on the necessity and urgency of recycling gold from both primary and secondary resources, the crucial role of biocyanidation, the present challenges and future directions toward commercial application of the process.
Jingxiu Wang; Fariborz Faraji; Juliana Ramsay; Ahmad Ghahreman. A review of biocyanidation as a sustainable route for gold recovery from primary and secondary low-grade resources. Journal of Cleaner Production 2021, 296, 126457 .
AMA StyleJingxiu Wang, Fariborz Faraji, Juliana Ramsay, Ahmad Ghahreman. A review of biocyanidation as a sustainable route for gold recovery from primary and secondary low-grade resources. Journal of Cleaner Production. 2021; 296 ():126457.
Chicago/Turabian StyleJingxiu Wang; Fariborz Faraji; Juliana Ramsay; Ahmad Ghahreman. 2021. "A review of biocyanidation as a sustainable route for gold recovery from primary and secondary low-grade resources." Journal of Cleaner Production 296, no. : 126457.
Low-grade metal resources generated during different mineral processing activities are increasing while there are not many economic and environmentally friendly techniques to manage them. There is no viable technique for the manganese extraction from low-grade ores as the conventional procedures are costly and environmentally unfriendly. In this research, the D-optimal response surface methodology has been used to optimize the bioleaching parameters. Varied contact methods (one-step, two-step, and spent medium), nutrition sources (sucrose and glucose), and pulp densities (1 g.L−1 to 10 g.L−1) were used in different experiments having been done in 30 days using Aspergillus niger. A maximum recovery of over 80% of Mn was achieved based on the acidolysis, complexolysis, and redoxolysis leaching of the organic acids produced by the fungi under the optimum condition; a two-step approach, in a glucose medium, and with a pulp density of 1 g.L−1. A kinetic study was also performed and revealed that the leaching mechanism was a mixed one which consisted of two stages (diffusion through the liquid film and a chemical reaction) for the first 12 day period, and a mechanism of diffusion through the product layer for the rest of the experiment.
Sahar Keshavarz; Fariborz Faraji; Fereshteh Rashchi; Mohammad Mokmeli. Bioleaching of manganese from a low-grade pyrolusite ore using Aspergillus niger: Process optimization and kinetic studies. Journal of Environmental Management 2021, 285, 112153 .
AMA StyleSahar Keshavarz, Fariborz Faraji, Fereshteh Rashchi, Mohammad Mokmeli. Bioleaching of manganese from a low-grade pyrolusite ore using Aspergillus niger: Process optimization and kinetic studies. Journal of Environmental Management. 2021; 285 ():112153.
Chicago/Turabian StyleSahar Keshavarz; Fariborz Faraji; Fereshteh Rashchi; Mohammad Mokmeli. 2021. "Bioleaching of manganese from a low-grade pyrolusite ore using Aspergillus niger: Process optimization and kinetic studies." Journal of Environmental Management 285, no. : 112153.
The decreasing grade of gold deposits and environmental regulations concerning the use of cyanide, a conventional extraction agent used in gold recovery, has highlighted the challenge in the field of gold extraction. The bioleaching of gold using microorganisms for in situ cyanide production to recover gold is a promising new approach for prohibiting the use of conventional chemical cyanide. For the first time, this study reports a comprehensive investigation on the role of pH on individual steps of Bacillus megaterium bacterial growth, cyanide production, and gold recovery. This novel way of maximizing biogenic cyanide is highly efficient and demonstrates biocyanidation as a potentially viable technique for direct treatment of sulfidic gold ores, i.e., eliminating the step of biooxidation for the first time. The low-grade sources were treated with both chemical cyanide and biogenic cyanide generated by B. megaterium. Results indicate that the bacteria generated a maximum of 61.89 ppm cyanide, which correspondingly recovered over 87% and 43% gold from O1 and O2 sources, respectively, comparable to gold recoveries by chemical leaching. The pure gold powder leaching was also performed to evaluate the loss in gold recovery due to the biosorption of gold to bacterial cells. The feasibility of the work is also supported by green chemistry metrics, and a comparison has been made between conventional and biocyanide leaching. The results revealed the potential of biocyanidation for industrial applications.
Fariborz Faraji; Jingxiu Wang; Harshit Mahandra; Ahmad Ghahreman. A Green and Sustainable Process for the Recovery of Gold from Low-Grade Sources Using Biogenic Cyanide Generated by Bacillus megaterium: A Comprehensive Study. ACS Sustainable Chemistry & Engineering 2020, 9, 236 -245.
AMA StyleFariborz Faraji, Jingxiu Wang, Harshit Mahandra, Ahmad Ghahreman. A Green and Sustainable Process for the Recovery of Gold from Low-Grade Sources Using Biogenic Cyanide Generated by Bacillus megaterium: A Comprehensive Study. ACS Sustainable Chemistry & Engineering. 2020; 9 (1):236-245.
Chicago/Turabian StyleFariborz Faraji; Jingxiu Wang; Harshit Mahandra; Ahmad Ghahreman. 2020. "A Green and Sustainable Process for the Recovery of Gold from Low-Grade Sources Using Biogenic Cyanide Generated by Bacillus megaterium: A Comprehensive Study." ACS Sustainable Chemistry & Engineering 9, no. 1: 236-245.
The objective of this study is to compare the reaction kinetics of copper leaching from chalcopyrite in acidic ferric sulfate media with (UAL) and without (non-UAL) ultrasound assistance. Four leaching parameters were evaluated and optimized. The parameter with the strongest effect was temperature, followed by ultrasonic power, the solid-to-liquid ratio (S/L), and acid concentration. Copper recovery showed an increase with rising temperatures in both systems. Ultrasonic power had a positive effect on copper leaching, but no significant difference was found among various power amplitudes. Copper extraction increased with decreasing S/L. At 0.1% S/L, the UAL leaching rate was double the non-UAL leaching rate. In both systems, acid concentration had little effect on copper extraction. Under optimized conditions, 20% amplitude power, 1% S/L, 0.5 M acid, and 80 °C leaching temperature, copper extraction was 50.4% and 57.5% in the non-UAL and UAL treatments, respectively. Ultrasonic waves enhanced the leaching rate, shortened the reaction time, and reduced acid consumption. Analysis of the rate-controlling step using a shrinking core model showed that leaching occurs after diffusion through the product layer but also chemical controlled in both non-UAL and UAL systems. The leaching mechanism was confirmed by characterizing the chalcopyrite and leached residue with X-ray diffraction and scanning electron microscopy/energy dispersive X-ray spectroscopy.
Jingxiu Wang; Fariborz Faraji; Ahmad Ghahreman. Effect of Ultrasound on the Oxidative Copper Leaching from Chalcopyrite in Acidic Ferric Sulfate Media. Minerals 2020, 10, 633 .
AMA StyleJingxiu Wang, Fariborz Faraji, Ahmad Ghahreman. Effect of Ultrasound on the Oxidative Copper Leaching from Chalcopyrite in Acidic Ferric Sulfate Media. Minerals. 2020; 10 (7):633.
Chicago/Turabian StyleJingxiu Wang; Fariborz Faraji; Ahmad Ghahreman. 2020. "Effect of Ultrasound on the Oxidative Copper Leaching from Chalcopyrite in Acidic Ferric Sulfate Media." Minerals 10, no. 7: 633.
Kinetics, as a fundamental requirement of nearly all industrial activities and engineering researches, plays a great role in leaching processes. Although there are many pieces of research on its application, there is not a clear pathway for investigating the kinetics of leaching and researchers usually follow different strategies in their studies. The conventional investigation techniques, which usually do not consider the mixed mechanisms and possibility of any change in the mechanism, normally include many calculations, plots, and inadequate capabilities to detect changes in the controlling mechanism of leaching. In this review, the main mathematical models of leaching and all possible scenarios are presented and discussed. The effect of various leaching parameters (including leaching agent, temperature, particle size, agitation, and solid to liquid ratio) on the rate of dissolution is summarized. Besides, two main approaches of rate determination step (single controlling mechanism and combined resistances method) are described and compared by reporting related equations and suitable examples. A technique to detect any changes in the leaching controlling mechanism is introduced and the alternatives to confirm the results are described. Additional models and equations were suggested for the cases that there is no agreement between data and the conventional models. Also, situations which are ignored in simple models (e.g., reversibility of the leaching reactions, adsorption and desorption of leached species, influence of charge and surface potential, existence of multiple reactants in the solid, galvanic effect, wide particle size distribution, etc.) to develop more legalistic models are discussed. Considering various possible mechanisms in the kinetics of leaching, equations are derived for industrial leaching reactors.
Fariborz Faraji; Amirhossein Alizadeh; Fereshteh Rashchi; Navid Mostoufi. Kinetics of leaching: a review. Reviews in Chemical Engineering 2019, -1, 1 .
AMA StyleFariborz Faraji, Amirhossein Alizadeh, Fereshteh Rashchi, Navid Mostoufi. Kinetics of leaching: a review. Reviews in Chemical Engineering. 2019; -1 (ahead-of-p):1.
Chicago/Turabian StyleFariborz Faraji; Amirhossein Alizadeh; Fereshteh Rashchi; Navid Mostoufi. 2019. "Kinetics of leaching: a review." Reviews in Chemical Engineering -1, no. ahead-of-p: 1.
Environmental restrictions and economic benefits have obliged countries to promote recycling processes from secondary resources like spent lithium ion batteries (LIBs) instead of using primary ones. In spite of the developments have been made on industrial scale for the technologies involved in recycling processes, most of these technologies suffer from lack of efficiency and echo-friendliness. To reduce the footprints of the recycling processes, several efforts are made. A major development area is the use of organic acids which are considered as promising agents for leaching of valuable metals from spent LIBs. In this review paper, we provided an overview of the recent status of the recycling technologies of spent LIBs using organic acids. For this purpose, necessity of green processes and advantage of organic acids in recycling of spent LIBs is discussed. To fully understand the effect of these agents, production, origin, application, and structure of organic acids that have been used in recovery of metals from spent LIBs are also addressed. Afterwards, recycling processes using organic acids, and benefits and drawbacks of using them are summarized and possible complexes formed by these agents are proposed. Eventually, development of different reducing agents, ultrasonic agitation, and evolution and future prospect of green processes in recycling of spent LIBs is reviewed.
Rabeeh Golmohammadzadeh; Fariborz Faraji; Fereshteh Rashchi. Recovery of lithium and cobalt from spent lithium ion batteries (LIBs) using organic acids as leaching reagents: A review. Resources, Conservation and Recycling 2018, 136, 418 -435.
AMA StyleRabeeh Golmohammadzadeh, Fariborz Faraji, Fereshteh Rashchi. Recovery of lithium and cobalt from spent lithium ion batteries (LIBs) using organic acids as leaching reagents: A review. Resources, Conservation and Recycling. 2018; 136 ():418-435.
Chicago/Turabian StyleRabeeh Golmohammadzadeh; Fariborz Faraji; Fereshteh Rashchi. 2018. "Recovery of lithium and cobalt from spent lithium ion batteries (LIBs) using organic acids as leaching reagents: A review." Resources, Conservation and Recycling 136, no. : 418-435.
In this study, Aspergillus niger (A. niger) as an environmentally friendly agent for fungal bioleaching of waste printed circuit boards (WPCBs) was employed. D-optimal response surface methodology (RSM) was utilized for optimization of the bioleaching parameters including bioleaching method (one step, two step and spent medium) and pulp densities (0.5 g L to 20 g L) to maximize the recovery of Zn, Ni and Cu from WPCBs. According to the high performance liquid chromatography analysis, citric, oxalic, malic and gluconic acids were the most abundant organic acids produced by A.niger in 21 days experiments. Maximum recoveries of 98.57% of Zn, 43.95% of Ni and 64.03% of Cu were achieved based on acidolysis and complexolysis dissolution mechanisms of organic acids. Based on the kinetic studies, the rate controlling mechanism for Zn dissolution at one step approach was found to be diffusion through liquid film, while it was found to be mixed control for both two step and spent medium. Furthermore, rate of Cu dissolution which is controlled by diffusion in one step and two step approaches, detected to be controlled by chemical reaction at spent medium. It was shown that for Ni, the rate is controlled by chemical reaction for all the methods studied. Eventually, it was understood that A. niger is capable of leaching 100% of Zn, 80.39% of Ni and 85.88% of Cu in 30 days.
Fariborz Faraji; Rabeeh Golmohammadzadeh; Fereshteh Rashchi; Navid Alimardani. Fungal bioleaching of WPCBs using Aspergillus niger: Observation, optimization and kinetics. Journal of Environmental Management 2018, 217, 775 -787.
AMA StyleFariborz Faraji, Rabeeh Golmohammadzadeh, Fereshteh Rashchi, Navid Alimardani. Fungal bioleaching of WPCBs using Aspergillus niger: Observation, optimization and kinetics. Journal of Environmental Management. 2018; 217 ():775-787.
Chicago/Turabian StyleFariborz Faraji; Rabeeh Golmohammadzadeh; Fereshteh Rashchi; Navid Alimardani. 2018. "Fungal bioleaching of WPCBs using Aspergillus niger: Observation, optimization and kinetics." Journal of Environmental Management 217, no. : 775-787.