Optimization of Microwave Reductive Roasting Process of Bauxite Residue

In this study, microwave-assisted heating is presented as a suitable method to transform the hematite and goethite contained in bauxite residue into magnetite, wüstite, and metallic iron, with a short processing time. The final target was the production of a sinter with strong magnetic properties, allowing the magnetic separation of Fe from the residue. The influence of microwave energy on the sample, the effect of irradiation time, and the carbon/bauxite residue mass ratio (C/BR) were the parameters that have been analyzed to optimize the process. Their optimized combination allowed transforming 79% of the iron present in the sinter into metallic iron. However, hercynite was also formed, and the presence of this mineralogical phase could be considered a possible drawback for its magnetic properties.

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A Combined Soda Sintering and Microwave Reductive Roasting Process of Bauxite Residue for Iron Recovery

Minerals ◽

10.3390/min11020222 ◽

2021 ◽

Vol 11 (2) ◽

pp. 222

Author(s):

Chiara Cardenia ◽

Efthymios Balomenos ◽

Pritii Wai Yin Tam ◽

Dimitrios Panias

Keyword(s):

Metallic Iron ◽

Bauxite Residue ◽

Separation Process ◽

Iron Recovery ◽

Optimum Conditions ◽

Microwave Furnace ◽

Roasting Process ◽

Alkali Leaching ◽

Leaching Residue ◽

Reductive Roasting

In this study an integrated process is presented as a suitable method to transform Fe3+ oxides present in bauxite residue into magnetic oxides and metallic iron through a microwave roasting reduction, avoiding the formation of hercynite (FeAl2O4). In the first step, all the alumina phases were transformed into sodium aluminates by adding sodium carbonate as a flux to BR and then leached out through alkali-leaching to recover alumina. Subsequently, the leaching residue was mixed with carbon and roasted by using a microwave furnace at the optimum conditions. The iron oxide present in the sinter was converted into metallic iron (98%). In addition, hercynite was not detected. The produced cinder was subjected to a wet high intensity magnetic separation process to separate iron from the other elements.

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Influence of Hydrofluoric Acid Leaching and Roasting on Mineralogical Phase Transformation of Pyrite in Sulfidic Mine Tailings

Minerals ◽

10.3390/min10060513 ◽

2020 ◽

Vol 10 (6) ◽

pp. 513 ◽

Cited By ~ 5

Author(s):

Babak Koohestani ◽

Ahmad Khodadadi Darban ◽

Pozhhan Mokhtari ◽

Esmaeel Darezereshki ◽

Erol Yilmaz ◽

...

Keyword(s):

Magnetic Properties ◽

Phase Transformation ◽

Iron Oxides ◽

Mine Tailings ◽

Hydrofluoric Acid ◽

Surface Characterization ◽

Acid Leaching ◽

Roasting Process ◽

Pyrite Content ◽

Mineralogical Phase

Under the oxidative roasting process, pyrite, as a major mineral in sulfidic mine tailings, can transform to iron oxides. Generated iron oxides, if exhibiting enough magnetic properties, can be recovered via magnetic separation resulting in partial mine tailings valorization. However, due to the presence of various minerals and sintering possibility, it is advantageous to remove impurities and increase the pyrite content of mine tailings prior to the roasting procedure. In this case, hydrofluoric acid that has no influence on pyrite can be used to leach most inorganic minerals, including aluminosilicates. Therefore, this study investigated and compared the influence of the roasting process with and without hydrofluoric acid leaching pretreatment on mineralogical phase transformation of pyrite and magnetic properties of thermally generated minerals. Several tests and analyses were performed to study mineralogical phase transformation, morphology, elemental composition, surface characterization, and magnetic properties. Results of this study indicated that without acid leaching pretreatment, pyrite was mainly transformed to hematite. However, via acid leaching, fluorine, as a more electronegative element over oxygen, entered the compound and neglected the role of oxygen in thermal oxidation, instead reducing sulfur content of pyrite to only form pyrrhotite.

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Photodegradation of p-Nitrophenol Catalyzed by ZnO/MWCNTs Composite Catalyst in Water

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.455-456.1339 ◽

2012 ◽

Vol 455-456 ◽

pp. 1339-1344 ◽

Cited By ~ 2

Author(s):

Zhe Qi Li ◽

Jing Yu Liu

Keyword(s):

Irradiation Time ◽

Solar Irradiation ◽

Composite Catalyst ◽

Catalyst Loading ◽

Optimal Conditions ◽

Mass Ratio ◽

Initial Substrate ◽

Effects Of Ph ◽

Potential Use ◽

Initial Substrate Concentration

Photodegradation ofp-nitrophenol catalyzed by ZnO/MWCNTs composite in water was investigated. The effects of pH, irradiation time, catalyst loading, initial substrate concentration and MWCNTs content on the degradation were investigated. Experiment results revealed that the optimal conditions were ap-nitrophenol concentration of 60.0 mg/L at pH 5.0 with catalyst loading of 10.0 g/L under solar irradiation for the illumination of 180 min. The highest efficiency on photodegradation ofp-nitrophenol can be achieved with an optimal MWCNTs/ZnO mass ratio of 0.16%. Possible decomposing mechanisms were also discussed. The repeatability of photocatalytic activity was tested. The photocatalyst was used ten cycles with degradation efficiency still higher than 95%. The results of the study showed the feasible and potential use of ZnO/MWCNTs composite in degradation of toxic organic pollutants.

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Growth of metallic iron particles during reductive roasting of boron-bearing magnetite concentrate

Journal of Central South University ◽

10.1007/s11771-020-4384-0 ◽

2020 ◽

Vol 27 (5) ◽

pp. 1484-1494

Author(s):

Xin Zhang ◽

Guang-hui Li ◽

Ming-jun Rao ◽

Huan-peng Mi ◽

Bin-jun Liang ◽

...

Keyword(s):

Metallic Iron ◽

Iron Particles ◽

Magnetite Concentrate ◽

Reductive Roasting

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Effects of Activated Carbon in Microwave Induction of Lateritic Ore

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.372.433 ◽

2013 ◽

Vol 372 ◽

pp. 433-436 ◽

Cited By ~ 2

Author(s):

He Chen ◽

Rui Guo ◽

Na Su ◽

Yue Hong Zhang ◽

Xuan Wen Liu

Keyword(s):

Activated Carbon ◽

Microwave Irradiation ◽

Stable Process ◽

Heating Time ◽

Heating Process ◽

Roasting Process ◽

Reductive Roasting ◽

Lateritic Ore ◽

Composition Of Products

Lateritic ore can be heated and deoxidized rapidly via microwave irradiation with activated carbon as deoxidizer. In this paper, we studied the reductive roasting behavior of carbon-containing lateritic ore in microwave field and the composition of products through different heating process with varying carbon content. The results show that the heating process of the lateritic ore is a thermally stable process. The reductive level of lateritic ore can be adjusted by changing the proportion of carbon powders and the heating time of microwave irradiation. During this reductive roasting process, the quality of the added carbon powders will make a great impact on the phase composition of the product and then affect the heating rate. The reductive calcite product mainly consists of magnetite and wastage. With the rising of the content of reducing agent, the reductive level of lateritic ore will increase, which cause Ni and a small quantity of Fe to be deoxidized and forms Ni-Fe alloy.

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Distribution Characteristics of Phosphorus in the Metallic Iron during Solid-State Reductive Roasting of Oolitic Hematite Ore

ISIJ International ◽

10.2355/isijinternational.isijint-2015-212 ◽

2015 ◽

Vol 55 (11) ◽

pp. 2304-2309 ◽

Cited By ~ 9

Author(s):

Guanghui Li ◽

Mingjun Rao ◽

Chongzhong Ouyang ◽

Shuhui Zhang ◽

Zhiwei Peng ◽

...

Keyword(s):

Solid State ◽

Metallic Iron ◽

Distribution Characteristics ◽

Hematite Ore ◽

Reductive Roasting ◽

Oolitic Hematite Ore

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Alumina Extraction from Red Mud by Magnetic Separation

Indonesian Journal of Chemistry ◽

10.22146/ijc.25102 ◽

2018 ◽

Vol 18 (2) ◽

pp. 331 ◽

Cited By ~ 2

Author(s):

Suprapto Suprapto ◽

Zahrotul Istiqomah ◽

Eko Santoso ◽

Ahmad Anwarud Dawam ◽

Didik Prasetyoko

Keyword(s):

Magnetic Separation ◽

Red Mud ◽

Inductively Coupled Plasma ◽

Aluminum Content ◽

Magnetic Phase ◽

Second Step ◽

Mass Ratio ◽

Carbon Reduction ◽

Inductively Coupled ◽

Roasting Process

Alumina extraction from red mud has been investigated by magnetic separation with three-step treatment. First, the addition of red mud with Na2CO3 (12 wt%) and heated at 110 °C for 4 h. The second step was carbon reduction using coal with mass ratio of (red mud+Na2CO3) : coal was 1:3 then roasted at temperature of 850, 950, and 1050 °C for 1, 2, and 3 h. The third step was magnetic separation. The magnetic separation was carried out in order to remove magnetite produced during roasting process. Magnetic and non-magnetic phases obtained were characterized by XRD and SEM-EDX techniques. The non-magnetic phase obtained was leached using HCl 6 M, and then aluminum content was determined by Inductively Coupled Plasma (ICP). The result revealed that the highest aluminum oxide extracted from the red mud was 20.66 wt% obtained by roasting at temperature of 1050 °C for 2 h.

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