Microwave assisted leaching investigation for the extraction of copper(II) and chromium(III) from spent catalyst (original) (raw)
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Microwave applications in mining and process metallurgy have been the subject of many research studies over the past two decades. This paper reviews microwave-assisted leaching of copper, gold, nickel, cobalt, and manganese, lead and zinc and also coal desulphurisation. It has been recognised that microwave technology has great potential to improve the extraction efficiency of metals in terms of both reduction in required leaching time and increased recovery of valuable metal. Despite a significant number of research studies in this area and potential for achieving highly attractive benefits, there is no agreement to the mechanism of interaction of microwaves with hydrometallurgical systems. D
Microwave-Leaching of Copper Smelting Dust for Cu and Zn Extraction
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Industrial wastes may contain high concentrations of valuable metals. Extraction and recovery of these metals have several economic and environmental advantages. Various studies showed positive effects of microwaves as a pretreatment method before the leaching of minerals. However, there are empty rooms for exploring simultaneous microwave and leaching (microwave-leaching) of industrial waste material for the production of valuable metals. This investigation examined the microwave-leaching method to extract copper and zinc from a copper-smelter dust (CSD). The results of microwave-leaching mechanism were compared with conventional heating leaching based on kinetics modelling. The final Cu recovery in the conventional heating and microwave irradiation was 80.88% and 69.83%, respectively. Kinetic studies indicated that the leaching reactions follow diffusion across the product layer. Based on X-ray powder diffraction (XRD) analyses, during conventional experiments sulfate; components ...
Oxygenated leaching of copper sulfide mineral under microwave-hydrothermal conditions
Journal of Minerals & Materials …, 2002
A study on microwave assisted chalcocite leaching was carried out with a microwave hydrothermal reactor. The leaching was conducted with thick mineral slurries (50-100g/l). The leaching media is a mixed solution of CuCl 2 and NaCl. The investigation included the effect of leaching temperature, quantities of the minerals per unit slurry volume as well as the initial concentration of cupric ions. The results were discussed and compared with using conventional leaching method.
Current Science
The main aim of the present study is to develop a new method to recover gold and other precious metals such as copper, silver, etc. with the judicious combination of microwave heating and acid leaching of e-waste samples like printed circuit board of computers, mobiles, electronic devices, etc. In the present study, microwave heating is much required for segregation of melted plastics and metals from e-waste and it also generates high temperature in much lesser time. The investigation basically consists of seven stages, i.e. heating the e-waste using microwave energy, grinding, physical separation of molten plastics and metal slag followed by leaching in nitric acid, leaching in aqua regia for unreacted materials, removing with concentrated nitric acid and washing and purifying the metal deposits. The results obtained from XRD, FESEM-EDAX and TEM studies confirm that precious metals like gold and silver can be obtained with the new method, which is also an environmental friendly approach.
World Academy of Science, Engineering and Technology, International Journal of Chemical, Molecular, Nuclear, Materials and Metallurgical Engineering, 2015
Microwave-assisted hydrodistillation (MAHD) is an advanced hydrodistillation (HD) technique, in which a microwave oven is used in the extraction process. MAHD and HD methods have been compared and evaluated for their effectiveness in the isolation of essential oils from fresh mango (Mangifera indica L.) flowers. MAHD offers important advantages over HD in terms of energy savings and extraction time (75 min against 4 h). The composition of the extracted essential oils was investigated by GC-FID and GC-MS. Results indicate that the use of microwave irradiation did not adversely influence the composition of the essential oils. MAHD was also found to be a green technology.
The influence of microwaves on the leaching kinetics of chalcopyrite
Minerals Engineering, 2005
The influence of microwave heating on the leaching kinetics of chalcopyrite has been investigated. Microwave-assisted leaching has been investigated in an attempt to improve the yields of extracted metal and reduce processing time. This is especially pertinent in view of the increased demand for more environmentally friendly processes.
The reality of non-thermal effects in microwave assisted leaching systems?
Hydrometallurgy, 2006
This work reports a fundamental study into the influence of microwave energy on the dissolution of sulphide minerals. Chalcopyrite and sphalerite were chosen as model materials due to their economic importance and the diversity of their heating behaviour in a microwave field. Leaching of both chalcopyrite and sphalerite in ferric sulphate under microwave conditions has shown enhanced recoveries of metal values compared to that produced conventionally. The enhanced copper recovery from chalcopyrite during microwave treatment is believed to be as a result of the selective heating of the mineral particles over the solution and also due to the superheated layer of the leaching solution close to the periphery of the reaction vessel which creates higher temperatures compared to the bulk solution temperature. The enhanced recovery of zinc from sphalerite seems to occur as a result of only the presence of the superheated layer. If leaching takes place within this layer, an apparent rate increase will be noted with respect to the measured bulk temperature. Negligible differences between the activation energy values under microwave and conventional conditions for both chalcopyrite and sphalerite. Furthermore, measurements of the dielectric properties of the leaching solutions have shown that such solutions are highly lossy and characterised by a penetration depth of an order of about 3 mm suggesting that most microwave power dissipate within the thin outer layer of the reactor. Finally, numerical electromagnetic simulations showed that chalcopyrite particles could be heated selectively when microwaved within highly lossy leaching solutions due to their high conductivity.
Optimization of microwave-assisted manganese leaching from electrolyte manganese residue
Green Processing and Synthesis, 2019
The process optimization of microwave assisted leaching of manganese from electrolytic manganese residue (EMR) was conducted. The Box-Behnken design (BBD) was utilized to determine the number of experiments as well as to assess the effect of the main leaching parameters, including the reaction temperature, reaction time, concentration of sulfuric acid and dosage of citric acid. A quadratic model was found to best fit the experimental data and was utilized to optimize the process parameters to maximize the percentage manganese recovery. 3-D response surface plots and contour plots were generated utilizing mathematical models to understand the effect of variables as well as to identify the optimal conditions. The optimum conditions of microwave assisted leaching were: temperature of 76°C, time of 55 min, H2SO4 concentration of 0.76 mol·L-1, dosage of citric acid of 3.51 mg/g. Under these conditions, the percentage manganese recovery higher than 90% could be achieved.
Separation and Purification Technology, 2021
Waste printed circuit boards (WPCBs) contain high amounts and various types of precious metals; thus, it is necessary to efficiently and selectively recover these metals by eco-friendly and economic means. An in-situ microwave-assisted leaching and selective separation process employing biphasic aqua regia-ionic liquid systems was developed herein. It was hypothesized that the combined technique can pulverize the WPCB sample, while simultaneously leaching Au(III) and Cu(II) from the WPCBs and affording selective separation using the ionic liquid (IL), i.e. [C 8 mim][(CF 3 SO 2) 2 N]. The results show that the microwave treatment increased the Au(III) and Cu(II) leaching efficiency by 45.56% and 10.83%, respectively, compared to the control test without microwave treatment, and the leached Au(III) and Cu(II) ions present in the aqua regia phase were simultaneously transferred into the IL phase, leading to high selective separation efficiencies, i.e. extraction rates of 95.50% and 1.26% for Au(III) and Cu(II), respectively. In the final stage, the concentrated Au(III) was back-stripped using 0.01 M thiourea in 0.1 M HCl solution. The recovery of Au(III) ions from the IL phase was 96.74 ± 2.19%. Consequently, it was revealed that microwave treatment in the aqua regia-IL phases can efficiently lead to pulverization of WPCBs and leaching of Au(III) and Cu(II), followed by selective separation of Au(III) from the leachate by the IL.
Scale up possibilities for microwave leaching of chalcopyrite in ferric sulphate
International Journal of Mineral Processing, 2006
This paper presents a study on the effect of reactor size on the microwave leaching outcome of copper from chalcopyrite in Fe 2 (SO 4 ) 3 −H 2 SO 4 solution. Microwave leaching experiments were carried out in single mode cavity using reactors of two sizes (20 and 50 mm in diameter). The results of microwave experiments were compared with those obtained under conventional conditions. It was found that the copper recovery obtained under microwave conditions in the large reactor is comparable to those obtained conventionally. On the other hand, the copper recovery was higher when leaching was carried out in small reactor. It is suggested that the enhanced recovery in the small reactor is due to the selective heating of chalcopyrite coupled with the effect of microwave penetration depth. Computational results also suggest that the portion of reactor volume affected by the high power density is higher in the small reactor. Furthermore, microwave heating of ferric sulphate leaching solution in vessels of different sizes suggests the presence of a super heated layer close to the vessel walls caused by a small penetration depth. Based on experimental and modelling evidence the implications for the scale up for microwave leaching of chalcopyrite are discussed.