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Characterization and Processing of Complex Materials

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A special issue of Materials (ISSN 1996-1944). This special issue belongs to the section "Advanced Materials Characterization".

Deadline for manuscript submissions: closed (31 December 2021) | Viewed by 28625

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Dr. Akira Otsuki

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Facultad de Ingeniería y Ciencias, Universidad Adolfo Ibáñez, Diagonal Las Torres 2640, Peñalolén 7941169, Santiago, Chile
Interests: mineral processing; recycling; colloid and interface science
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Special Issue Information

Dear Colleagues,

This Special Issue aims to provide forum for scientists and engineers to share and discuss their pioneering/original findings or insightful reviews on the Characterization and Processing of Complex Materials. Reports on achievement of coupling the complexity of industrial materials/wastes/natural ores with non-destructive characterization method(s) and the unique advancement of their processing are particularly encouraged. On the other hand, any kind of contribution under the broad framework of the understanding and production of complex materials is also highly welcome.

Some potential contributions are listed below under “keywords”. One of them is the waste management and recycling of complex materials (e.g. foods, electronic wastes) via the development of a new characterization method and/or process intensification. For example, a proper characterization of complex/heterogeneous materials is still an extremely challenging task, since the majority of characterization methods analyze either the average characteristics of the whole material or a narrow area of specific interest [1,2]. On the other hand, the efficient processing/recycling of complex materials/wastes should be strongly supported by their characterization from the viewpoint of economic and environmental concerns [1].

[1] Otsuki, A.; Chen, Y.; Zhao, Y. Characterisation and beneficiation of complex ores for sustainable use of mineral resources: Refractory gold ore beneficiation as an example. Int. J. Soc. Mat. Eng. Res. 2014, 20, 126–135.

[2] Otsuki, A.; Bryant, G. Characterization of the interactions within fine particle mixtures in highly concentrated suspensions for advanced particle processing. Adv. Colloid Interface Sci. 2015, 226, 37–43.

Dr. Akira Otsuki
Guest Editor

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Keywords

Non-destructive characterization
Analytical chemistry and instrumentation
Waste management and recycling
Selective material recovery/processing
Sustainability and circular economy

Published Papers (11 papers)

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Editorial

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3 pages, 188 KiB

Open AccessEditorial

Editorial for the Special Issue: “Characterization and Processing of Complex Materials”

by Akira Otsuki

Materials 2023, 16(10), 3830; https://doi.org/10.3390/ma16103830 - 19 May 2023

Viewed by 870

Abstract

The Special Issue aimed to provide a forum for scientists and engineers to share and discuss their pioneering/original findings or insightful reviews on the “Characterization and Processing of Complex Materials” [...] Full article

(This article belongs to the Special Issue Characterization and Processing of Complex Materials)

Research

Jump to: Editorial

19 pages, 4011 KiB

Open AccessEditor’s ChoiceArticle

The Influence of Air Nanobubbles on Controlling the Synthesis of Calcium Carbonate Crystals

by Yongxiang Wu, Minyi Huang, Chunlin He, Kaituo Wang, Nguyen Thi Hong Nhung, Siming Lu, Gjergj Dodbiba, Akira Otsuki and Toyohisa Fujita

Materials 2022, 15(21), 7437; https://doi.org/10.3390/ma15217437 - 23 Oct 2022

Cited by 4 | Viewed by 1728

Abstract

Numerous approaches have been developed to control the crystalline and morphology of calcium carbonate. In this paper, nanobubbles were studied as a novel aid for the structure transition from vaterite to calcite. The vaterite particles turned into calcite (100%) in deionized water containing nanobubbles generated by high-speed shearing after 4 h, in comparison to a mixture of vaterite (33.6%) and calcite (66.3%) by the reaction in the deionized water in the absence of nanobubbles. The nanobubbles can coagulate with calcite based on the potential energy calculated and confirmed by the extended DLVO (Derjaguin–Landau–Verwey–Overbeek) theory. According to the nanobubble bridging capillary force, nanobubbles were identified as the binder in strengthening the coagulation between calcite and vaterite and accelerated the transformation from vaterite to calcite. Full article

(This article belongs to the Special Issue Characterization and Processing of Complex Materials)

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16 pages, 3557 KiB

Open AccessArticle

Equivalent Circuit Models: An Effective Tool to Simulate Electric/Dielectric Properties of Ores—An Example Using Granite

by Kyosuke Fukushima, Mahmudul Kabir, Kensuke Kanda, Naoko Obara, Mayuko Fukuyama and Akira Otsuki

Materials 2022, 15(13), 4549; https://doi.org/10.3390/ma15134549 - 28 Jun 2022

Cited by 2 | Viewed by 1733

Abstract

The equivalent circuit model is widely used in high-voltage (HV) engineering to simulate the behavior of HV applications for insulation/dielectric materials. In this study, equivalent circuit models were prepared in order to represent the electric and dielectric properties of minerals and voids in a granite rock sample. The HV electric-pulse application shows a good possibility of achieving a high energy efficiency with the size reduction and selective liberation of minerals from rocks. The electric and dielectric properties were first measured, and the mineral compositions were also determined by using a micro-X-ray fluorescence spectrometer. Ten patterns of equivalent circuit models were then prepared after considering the mineral distribution in granite. Hard rocks, as well as minerals, are dielectric materials that can be represented as resistors and capacitors in parallel connections. The values of the electric circuit parameters were determined from the known electric and dielectric parameters of the minerals in granite. The average calculated data of the electric properties of granite agreed with the measured data. The conductivity values were 53.5 pS/m (measurement) and 36.2 pS/m (simulation) in this work. Although there were some differences between the measured and calculated data of dielectric loss (tanδ), their trend as a function of frequency agreed. Even though our study specifically dealt with granite, the developed equivalent circuit model can be applied to any other rock. Full article

(This article belongs to the Special Issue Characterization and Processing of Complex Materials)

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14 pages, 2632 KiB

Open AccessArticle

Simulation of Electrical and Thermal Properties of Granite under the Application of Electrical Pulses Using Equivalent Circuit Models

by Kyosuke Fukushima, Mahmudul Kabir, Kensuke Kanda, Naoko Obara, Mayuko Fukuyama and Akira Otsuki

Materials 2022, 15(3), 1039; https://doi.org/10.3390/ma15031039 - 28 Jan 2022

Cited by 5 | Viewed by 2622

Abstract

Since energy efficiency in comminution of ores is as small as 1% using a mechanical crushing process, it is highly demanded to improve its efficiency. Using electrical impulses to selectively liberate valuable minerals from ores can be a solution of this problem. In this work, we developed a simulation method using equivalent circuits of granite to better understand the crushing process with high-voltage (HV) electrical pulses. From our simulation works, we calculated the electric field distributions in granite when an electrical pulse was applied. We also calculated other associated electrical phenomena such as produced heat and temperature changes from the simulation results. A decrease in the electric field was observed in the plagioclase with high electrical conductivity and void space. This suggests that the void volume in each mineral is important in calculating the electrical properties. Our equivalent circuit models considering both the electrical conductivity and dielectric constant of a granite can more accurately represent the electrical properties of granite under HV electric pulse application. These results will help us better understand the liberation of minerals from granite by electric pulse application. Full article

(This article belongs to the Special Issue Characterization and Processing of Complex Materials)

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20 pages, 6822 KiB

Open AccessArticle

Long-Term Stability of Different Kinds of Gas Nanobubbles in Deionized and Salt Water

by Yali Zhou, Zhenyao Han, Chunlin He, Qin Feng, Kaituo Wang, Youbin Wang, Nengneng Luo, Gjergj Dodbiba, Yuezhou Wei, Akira Otsuki and Toyohisa Fujita

Materials 2021, 14(7), 1808; https://doi.org/10.3390/ma14071808 - 06 Apr 2021

Cited by 35 | Viewed by 4211

Abstract

Nanobubbles have many potential applications depending on their types. The long-term stability of different gas nanobubbles is necessary to be studied considering their applications. In the present study, five kinds of nanobubbles (N₂, O₂, Ar + 8%H₂, air and CO₂) in deionized water and a salt aqueous solution were prepared by the hydrodynamic cavitation method. The mean size and zeta potential of the nanobubbles were measured by a light scattering system, while the pH and Eh of the nanobubble suspensions were measured as a function of time. The nanobubble stability was predicted and discussed by the total potential energies between two bubbles by the extended Derjaguin–Landau–Verwey–Overbeek (DLVO) theory. The nanobubbles, except CO₂, in deionized water showed a long-term stability for 60 days, while they were not stable in the 1 mM (milli mol/L) salt aqueous solution. During the 60 days, the bubble size gradually increased and decreased in deionized water. This size change was discussed by the Ostwald ripening effect coupled with the bubble interaction evaluated by the extended DLVO theory. On the other hand, CO₂ nanobubbles in deionized water were not stable and disappeared after 5 days, while the CO₂ nanobubbles in 1 mM of NaCl and CaCl₂ aqueous solution became stable for 2 weeks. The floating and disappearing phenomena of nanobubbles were estimated and discussed by calculating the relationship between the terminal velocity of the floating bubble and bubble size. Full article

(This article belongs to the Special Issue Characterization and Processing of Complex Materials)

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14 pages, 5296 KiB

Open AccessArticle

Non-Destructive Imaging on Synthesised Nanoparticles

by Kelvin Elphick, Akinobu Yamaguchi, Akira Otsuki, Neil Lonio Hayagan and Atsufumi Hirohata

Materials 2021, 14(3), 613; https://doi.org/10.3390/ma14030613 - 29 Jan 2021

Cited by 5 | Viewed by 2763

Abstract

Our recently developed non-destructive imaging technique was applied for the characterisation of nanoparticles synthesised by X-ray radiolysis and the sol-gel method. The interfacial conditions between the nanoparticles and the substrates were observed by subtracting images taken by scanning electron microscopy at controlled electron acceleration voltages to allow backscattered electrons to be generated predominantly below and above the interfaces. The interfacial adhesion was found to be dependent on the solution pH used for the particle synthesis or particle suspension preparation, proving the change in the particle formation/deposition processes with pH as anticipated and agreed with the prediction based on the Derjaguin–Landau–Verwey–Overbeek (DLVO) theory. We found that our imaging technique was useful for the characterisation of interfaces hidden by nanoparticles to reveal the formation/deposition mechanism and can be extended to the other types of interfaces. Full article

(This article belongs to the Special Issue Characterization and Processing of Complex Materials)

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11 pages, 6304 KiB

Open AccessArticle

High-Temperature Mechanical Behaviors of SiO₂-Based Ceramic Core for Directional Solidification of Turbine Blades

by Jiangwei Zhong and Qingyan Xu

Materials 2020, 13(20), 4579; https://doi.org/10.3390/ma13204579 - 14 Oct 2020

Cited by 17 | Viewed by 1985

Abstract

The high-temperature mechanical behaviors of SiO₂-based ceramic cores for the directional solidification of turbine hollow blades were investigated. Isothermal uniaxial compression tests of ceramic core samples were conducted on a Gleeble-1500D mechanical simulator with an innovative auxiliary thermal system. The stress–strain results and macro- and micro- structures of SiO₂-based ceramic cores were investigated experimentally. The microstructures were characterized by the scanning electron microscope (SEM). Based on the experimental data, a nonlinear constitutive model for high temperature compressive damage was established. The statistical results of Weibull moduli show that the stability of hot deformation increases with the increase of temperature. The fracture type of the SiO₂-based core samples is brittle fracture, but when the temperature exceeds 1400 °C, the mechanical behavior exhibits thermo-viscoelastic and viscoplastic property. Under high-temperature (>1400 °C) and stress conditions, the strength of the ceramic core is weakened owing to the viscous slip of SiO₂, which is initially melted at the temperature of 1400 °C. The comparison results between the predictions of nonlinear model and experimental values indicate that the model is applicable. Full article

(This article belongs to the Special Issue Characterization and Processing of Complex Materials)

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18 pages, 12340 KiB

Open AccessArticle

Reactivity of Low-Grade Chromite Concentrates towards Chlorinating Atmospheres

by Ndue Kanari, Eric Allain, Lev Filippov, Seit Shallari, Frédéric Diot and Fabrice Patisson

Materials 2020, 13(20), 4470; https://doi.org/10.3390/ma13204470 - 09 Oct 2020

Cited by 3 | Viewed by 2028

Abstract

The most economically important iron-chromium bearing minerals is chromite. In natural deposits, iron(II) is frequently substituted by magnesium(II) while chromium(III) is replaced by aluminum(III) and/or iron(III) forming a complex chromium bearing material. The majority of mined chromite is intended for the production of ferrochrome which requires a chromite concentrate with high chromium-to-iron ratio. Found mostly in the spinel chromite structure, iron cannot be removed by physical mineral processing methods. In this frame, the present work deals with the reaction of chlorine and chlorine+oxygen with selected samples of chromite concentrates for assessing the reactivity of their components towards chlorinating atmosphere, allowing the preferential removal of iron, hence meeting the chromite metallurgical grade requirements. Isothermal thermogravimetric analysis was used as a reliable approach for the kinetic reactivity investigation. Results indicated a wide difference in the thermal behavior of chromite constituents in a chlorinating atmosphere when considering their respective values of apparent activation energy oscillating from about 60 to 300 kJ/mol as a function of the sample reacted fraction. During the chromite treatment by chlorine in presence of oxygen, chromium was recovered as liquid chromyl chloride by condensation of the reaction gas phase. Full article

(This article belongs to the Special Issue Characterization and Processing of Complex Materials)

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21 pages, 5979 KiB

Open AccessArticle

Thermochemical Route for Extraction and Recycling of Critical, Strategic and High-Value Elements from By-Products and End-of-Life Materials, Part II: Processing in Presence of Halogenated Atmosphere

by Ndue Kanari, Eric Allain, Seit Shallari, Frédéric Diot, Sébastien Diliberto, Fabrice Patisson and Jacques Yvon

Materials 2020, 13(18), 4203; https://doi.org/10.3390/ma13184203 - 21 Sep 2020

Cited by 6 | Viewed by 2246

Abstract

During the treatment of copper anode slime (CAS) under an air atmosphere, several aspects of the interactions of its main components (CuAgSe, Cu_2−xSe_yS_1−y, Ag₃AuSe₂) with oxygen were described in Part I. As a comparative and complementary study, this work deals with the thermal behavior of CAS under air in the presence of polyvinyl chloride (PVC) between 195 and 770 °C. The preliminary thermal treatment of an e-waste sample containing brominated substances was also performed. The reaction products were systematically analyzed by scanning electron microscopy through energy-dispersive spectroscopy (SEM-EDS) and X-ray diffraction (XRD) to investigate the thermal behaviors of the studied samples in a halogenated medium. At low temperatures, the copper, silver and selenium compounds of the CAS reacted with the HCl, issued from PVC degradation, leading to the formation of their respective chlorides. Bromides of valuable metals (Cu, Pb, Sn…) were synthesized during the e-waste treatment at 500 °C and they were distributed between the solid residue and gaseous phase. The data obtained give an insight into the reactivity of several metals towards halogenated substances, which may be valuable information for conducting the extraction and recycling of targeted elements from industrial by-products and end-of-life materials by a thermochemical route. Full article

(This article belongs to the Special Issue Characterization and Processing of Complex Materials)

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17 pages, 4009 KiB

Open AccessFeature PaperArticle

Green Process for Industrial Waste Transformation into Super-Oxidizing Materials Named Alkali Metal Ferrates (VI)

by Ndue Kanari, Etleva Ostrosi, Cécile Diliberto, Inna Filippova, Seit Shallari, Eric Allain, Frederic Diot, Fabrice Patisson and Jacques Yvon

Materials 2019, 12(12), 1977; https://doi.org/10.3390/ma12121977 - 19 Jun 2019

Cited by 6 | Viewed by 3199

Abstract

The investigation presented here features the design of a cleaner and greener chemical process for the conversion of industrial wastes into super-oxidizing materials. The waste of interest is the iron sulfate heptahydrate (FeSO₄·7H₂O) mainly generated through the sulfate route used for titanium dioxide industrial production. The products of this transformation process are alkali ferrates (A₂FeO₄, A = Na, K) containing iron in its hexavalent state and considered as powerful oxidants characterized by properties useful for cleaning waters, wastewaters, and industrial effluents. The proposed process includes two steps: (i) The first step consisting of the pre-mixing of two solids (AOH with FeSO₄·xH₂O) in a rotary reactor allowing the coating of iron sulfate in the alkali hydroxides through solid–solid reactions; and (ii) the second step involves the synthesis of alkali ferrates in a fluidized bed by oxidation of the single solid obtained in the first step in diluted chlorine. The chemical synthesis of alkali ferrates can be carried out within a timeframe of a few minutes. The usage of a fluidized bed enhanced the energy and mass transfer allowing a quasi-complete control of the ferrate synthesis process. The alkali ferrate synthesis process described here possesses many characteristics aligned with the principles of the “green chemistry”. Full article

(This article belongs to the Special Issue Characterization and Processing of Complex Materials)

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13 pages, 10428 KiB

Open AccessArticle

Thermochemical Route for Extraction and Recycling of Critical, Strategic and High Value Elements from By-Products and End-of-Life Materials, Part I: Treatment of a Copper By-Product in Air Atmosphere

by Ndue Kanari, Eric Allain, Seit Shallari, Frederic Diot, Sebastien Diliberto, Fabrice Patisson and Jacques Yvon

Materials 2019, 12(10), 1625; https://doi.org/10.3390/ma12101625 - 17 May 2019

Cited by 17 | Viewed by 3435

Abstract

Development of our modern society requests a number of critical and strategic elements (platinum group metals, In, Ga, Ge…) and high value added elements (Au, Ag, Se, Te, Ni…) which are often concentrated in by-products during the extraction of base metals (Cu, Pb, Zn…). Further, recycling of end-of-life materials employed in high technology, renewable energy and transport by conventional extractive processes also leads to the concentration of such chemical elements and their compounds in metallurgical by-products and/or co-products. One of these materials, copper anode slime (CAS), derived from a copper electrolytic refining factory, was used for this study. The sample was subjected to isothermal treatment from 225 to 770 °C under air atmosphere and the reaction products were systematically analyzed by scanning electron microscopy through energy dispersive spectroscopy (SEM-EDS) and X-ray diffraction (XRD) to investigate the thermal behavior of the treated sample. The main components of the anode slime (CuAgSe, Cu_2-xSe_yS_1-y, Ag₃AuSe₂) react with oxygen, producing mostly copper and selenium oxides as well as Ag-Au alloys as final products at temperatures higher than 500 °C. Selenium dioxide (SeO₂) is volatilized and recovered in pure state by cooling the gaseous phase, whilst copper(II) oxide, silver, gold and tellurium remain in the treatment residue. Full article

(This article belongs to the Special Issue Characterization and Processing of Complex Materials)

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