Akira Otsuki

Akira Otsuki
Luleå University of Technology | LTU · Department of Civil, Environmental and Natural resources engineering

PhD
Non-destructive characterization and selective recovery of complex materials

About

126
Publications
30,011
Reads
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816
Citations
Additional affiliations
August 2019 - present
Luleå University of Technology
Position
  • Visiting Professor
Description
  • Non-destructive characterization and selective material recovery
June 2017 - August 2017
The University of Tokyo
Position
  • Visiting Professor

Publications

Publications (126)
Article
Full-text available
There has been much attention paid to the utilization of complex ores due to decreasing the accessibility of high grade and easily extractable ores. In order to maintain the sustainable use of mineral resources, the effective beneficiation of complex ores is urgently required with the strong assist from mineralogical characterisation. In this paper...
Article
Full-text available
Characterization of heterogeneous materials, such as particles from mechanically processed waste printed circuit boards, is a challenging task. The majority of characterization methods either give average information or information that is very limited and in a tiny area of specific interest. That said, capturing such heterogeneity is significantly...
Article
Full-text available
High energy consumption in size reduction operations is one of the most significant issues concerning the sustainability of raw material beneficiation. Thus, process optimization should be done to reduce energy consumption. This study aimed to investigate the applicability of artificial neural networks (ANNs) to predict the particle size distributi...
Article
Full-text available
Despite the importance of solid concentration in froth flotation, its effect on flotation kinetics and entrainment has rarely been studied. In this study, the flotation kinetics and entrainment in quartz and hematite single-mineral flotation systems as a function of the solid concentration and particle size were investigated using dodecylamine acet...
Article
The zeta potential of single and multi‐inorganic fine particle mixtures (hematite and gangues, i.e., SiO2+Al2O3) with Na‐bentonite was investigated to understand and properly control the mineral surface properties relevant to pelletization of low grade fine iron ores. The zeta potential of hematite‐bentonite mixture showed more negative charge up t...
Article
Full-text available
This study aimed to characterize interactions within colloidal silica particles in their concentrated suspensions, using rheo-confocal measurements and imaging , followed by image analysis. We studied the effect of shear rate (0-500 s-1) and solution pH (6, 10) on the dispersion degree of colloidal silica particles via the determination and compari...
Article
CaCO3 crystals ranging from 3 to 15 μm in size have sparked significant scientific attention in many areas, such as materials, chemicals, medicine, and the environment. This study proposed a novel method for synthesizing flower-like vaterite calcium carbonate using nanobubble-containing ethanol and water mixed solution as the solvent based on the d...
Conference Paper
Full-text available
Our series of works on non-destructive characterization of milled printed circuit board (PCB) particles were summarized. The works can be categorized into elemental/metal distribution analysis and liberation analysis based on the elemental assay and image analysis. The elemental assay was performed with X-ray fluorescence spectroscopy (XRF) and pr...
Book
Non-Destructive Material Characterization Methods provides readers with a trove of theoretical and practical insight into how to implement different non-destructive testing methods for effective material characterization. The book starts with an introduction to the field before moving right into a discussion of a wide range of techniques that can b...
Book
Full-text available
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”. Reports on the achievement of coupling the complexity of industrial materials/wastes/natural ores with non-destructive characterization m...
Article
Full-text available
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” [...]
Article
Full-text available
Nanobubbles have been applied in many fields, such as environmental cleaning, material production, agriculture, and medicine. However, the measured nanobubble sizes differed among the measurement methods, such as dynamic light scattering, particle trajectory, and resonance mass methods. Additionally, the measurement methods were limited with respec...
Article
Today, communication links and networks are essential in transmitting data and information. Moreover, information sharing in communication devices and networks has become necessary, routine, and unavoidable. Consequently, designing and manufacturing high-speed nano-scale devices with ultra-low power consumption is very important. Among the emerging...
Article
Full-text available
Rare earth oxides such as La2O3 and Gd2O3 are abundant in waste optical glass. The separation of rare earth oxides is beneficial to the recycling of rare earth resources. In this study, the rare earth oxide Gd2O3 particles were separated from La2O3 particles using high gradient magnetic separation , and the influence of different fluid media (i.e.,...
Article
Full-text available
Reversible logic enables ultra-low power circuit design and quantum computation. Quantum dot Cellular Automata (QCA) is the most promising technology considered to implement reversible circuits, mainly due to the correspondence between features of reversible and QCA circuits. This work aims to push forward the state-of-the-art of the QCA-based reve...
Article
Full-text available
SRAM or Static Random-Access Memory is the most vital memory technology. SRAM is fast and robust but faces design challenges in nanoscale CMOS such as high leakage, power consumption, and reliability. Quantum-dot Cellular Automata (QCA) is the alternative technology that can be used to address the challenges of conventional SRAM. In this paper, a c...
Article
Full-text available
A nano-scale quantum-dot cellular automaton (QCA) is one of the most promising replacements for CMOS technology. Despite the potential advantages of this technology, QCA circuits are frequently plagued by numerous forms of manufacturing faults (such as a missing cell, extra cell, displacement cell, and rotated cell), making them prone to failure. A...
Article
Full-text available
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,...
Article
Full-text available
With the growing use of quantum-dot cellular automata (QCA) nanotechnology, digital circuits designed at the Nanoscale have a number of advantages over CMOS devices, including the lower utilization of power, increased processing speed of the circuit, and higher density. There are several flip flop designs proposed in the literature with their reali...
Article
Full-text available
In very large-scale integration (VLSI) circuits, a partial of energy lost leads to information loss in irreversible computing because, in conventional combinatorial circuits, each bit of information generates heat and power consumption, thus resulting in energy dissipation. When information is lost in conventional circuits, it will not be recoverab...
Article
Full-text available
Due to the development of integrated circuits and the lack of responsiveness to existing technology, researchers are looking for an alternative technology. Quantum-dot cellular automata (QCA) technology is one of the promising alternatives due to its higher switch speed, lower power dissipation, and higher device density. One of the most important...
Article
Full-text available
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 applic...
Conference Paper
The importance and need for rare metals are increasing rapidly nowadays for the economic development of countries as more & more green technologies are coming on stream and being used. Rare earths are considered a strategical critical raw material (critical metals), thus identification and documentation of the key characteristics/parameters of thei...
Article
This study found that with the help of O 2 nanobubble pre-oxidation treatment, effective arsenic removal was successfully achieved and is expected to be applicable on an industrial scale. The main research findings to remove arsenic are as follows. The oxidation of As(III) by blowing out O 2 nanobubbles, O 2 millimeter-sized bubbles, and air nanobu...
Conference Paper
Full-text available
The Alces Lake REE-Th-U mineralization area is located approximately 28 km north of the Athabasca basin margin and is ranked as the highest-grade REE occurrence in Canada. The mineralized pegmatites are emplaced within/near the Archean/Paleoproterozoic transition zone under middle crustal P-T conditions and form polyphase anatectic pods/boudins/zon...
Article
Full-text available
In a flotation process, the particle–bubble and particle–particle interactions are key factors influencing collection efficiencies. In this work, the generalized Sutherland equation collision model and the modified Dobby–Finch attachment model for potential flow conditions were used to calculate the efficiencies of particle–bubble collision and att...
Article
Full-text available
This paper summarizes and discusses previous investigations into the correlation between the rheology and flotation process of fine particle suspensions. This summary provides a better understanding of the challenges and current status of this subject and useful feedback based on the revision of relevant theories and practical implications for fine...
Article
Full-text available
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...
Article
Full-text available
In this study, 8% hydrogen (H2) in argon (Ar) and carbon dioxide (CO2) gas nanobubbles was produced at 10, 30, and 50 vol.% of ethanol aqueous solution by the high-speed agitation method with gas. They became stable for a long period (for instance, 20 days), having a high negative zeta potential (−40 to −50 mV) at alkaline near pH 9, especially for...
Article
Nowadays, rare earth elements (REEs), which belong to the group of rare metals, are considered worldwide to be strategic critical raw materials and are extremely important for the economic development of any country. Various methods and approaches are used for prospecting and exploration of deposits of these critical metals; among which the methods...
Conference Paper
Представлено основні підходи та типи даних, що використовують при побудові 2Д/3Д/4Д моделей з ціллю пошуків та розвідки та подальшого дослідження родовищ рідкоземельних елементів. Для дослідження було обрано родовища Альсез Лейк (в межах Канадськаого щита) та Дібровське (Український щит). Here we present the main approaches and types of data used...
Article
Full-text available
Quantum-dot Cellular Automata (QCA) is an innovative paradigm bringing hopeful applications in the perceptually novel computing layout in quantum electronics. The circuits manufactured by QCA technology can provide a notable decrease in size, rapid-switching velocity, and ultra-low power utilization. The demultiplexer is a beneficial component to o...
Article
Since the 1950s all through the 1670s there has been a considerable economic growth of the least developed and devolving countries nowadays. The world will certainly demand more raw materials to sustain this growth, and therefore their supply will need proper adjustments to keep the material market stable. The possibility of supply shortage has bee...
Conference Paper
The Alces lake project is located within the Beaverlodge Domain (northern Saskatchewan), approximately 28 km north of the Athabasca Basin margin and is ranked as the highest-grade REE occurrence in Canada. The REE-Th-U mineralization at Alces Lake is hosted in monazite-rich granitic to residual melt/cumulate pegmatites, which are associated with bi...
Article
Full-text available
Quantum-dot cellular automata (QCA) nanotechnology is a practical suggestion for replacing present silicon-based technologies. It provides many benefits, such as low power usage, high velocity, and an extreme density of logic functions on a chip. In contrast, designing circuits with no waste of information (reversible circuits) may further reduce e...
Conference Paper
Full-text available
Structural mapping, including lineament analysis, is an important geological tool used to identify the prevailing tectonic trends within a study area. Lineaments are straight to curvilinear landforms that are widely distributed across the Earth’s surface and are closely related to underground concealed structures, such as faults, shear zones, and f...
Article
Full-text available
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 cavit...
Article
Full-text available
Our recently developed non-destructive imaging technique was applied for the characterisation of nano-particles synthesised by X-ray radiolysis and sol-gel method. The interfacial conditions between the nano-particles and the substrates were observed by subtracting images taken by scanning electron microscopy at controlled electron acceleration vol...
Article
Full-text available
This paper investigates the reactions involved when LiNi0.8Mn0.1Co0.1O2 (NMC 811), which is one of the most promising positive electrodes for the next generation of lithium-ion batteries, is leached by hydrochloric acid. This study shows that the leaching behaviour of lithiumis quite different than those observed for nickel, cobalt and manganese co...
Article
This work aimed to develop and propose methods for evaluating the metal degree of liberation to characterize the metal deportment/concentration and liberation/association of mechanically processed waste Printed Circuit Boards (PCBs) that hold the complex and heterogeneity structure and metal distribution/association. Waste PCBs passed through a ser...
Chapter
This article summarizes the series of different methodologies to evaluate rheology of colloidal particle suspensions and different approaches to correlate this macroscopic behavior with microscopic particle–particle interaction. This includes the coupling suspension yield stress and Derjaguin–Landau–Verwey–Overbeek forces, i.e., van der Waals and e...
Chapter
This chapter summarizes the series of different developments and investigations on in situ coupling of rheology with small-angle scattering (rheo-SAS) measurements of colloidal particle suspensions. This coupling allows us to directly correlate microscopic particle–particle interaction with macroscopic suspension behavior under different physical a...
Article
Full-text available
Selective/preferential milling of printed circuit board (PCB) particles followed by non-destructive characterization of the mill products was performed in order to understand the effects of different feed masses into a hammer mill and different milling time on the metal recovery and enrichment ratio. Those are important variables affecting and dete...
Conference Paper
Occupational health and safety standards are guidelines to keep workers and the environment safe. They are constantly improving and getting stricter on what hazardous materials are allowed to be stored and used in mine sites. As with most metallurgical processes, coal processing uses chemicals to improve its performance. One of the main chemicals u...
Conference Paper
The purpose of the present work was to perform the cost comparison between two different two-liquid flotation methods to selectively recover ultra-fine fluorescent powders for material recycling. Two-liquid flotation utilizes the interface of two-liquids with different polarities (i.e. polar and non-polar solvents) and surfactant to selectively hyd...
Conference Paper
This article reports the series of different investigations on in-situ coupling of rheology with small-angle scattering (rheo-SAS) measurements of colloidal particle suspensions. This coupling allows us to directly correlate microscopic particle-particle interactions with macroscopic suspension behavior under different physical and chemical environ...
Conference Paper
This research aimed to investigate the effect of different milling method applications, based on different principles and forces on the size reduction of particles generated from printed circuit boards (PCBs). First a shredder was used to prepare -10 mm PCB particles with 2 different exit sieve opening sizes. Using shredded particles, several diffe...
Article
Full-text available
This work aimed to characterize the deportment/concentration and liberation/association of the metals and light elements within mechanically processed waste printed circuit boards (PCBs) that hold the complex and heterogeneous structure and distribution of different material components. Waste PCBs passed through a series of mechanical processing (i...
Article
Full-text available
A safer frother option for coal flotation in comparison with the common frother methyl isobutyl carbinol (MIBC) was searched and compared through literature review. Results of literature review and comparison of different frothers in safety and environmental aspects show that pine oil and DowFroth have a strong potential to replace MIBC since it ha...
Article
Full-text available
This study investigates dilute aqueous suspensions of bentonite particles using magnetic resonance imaging (MRI) velocimetry. Four different chemical conditions are tested to investigate the influence of pH and type of monovalent electrolyte on the local rheological behavior of bentonite suspensions. The results indicate the shear banding in a dilu...
Article
Full-text available
This study investigated the use of solvent contrast (H2O/D2O ratio) as a means to optimize the ultra-small-angle neutron scattering (USANS) signal. By optimizing the signal, it was possible to reduce the undesirable effects of coherent multiple scattering while still maintaining a measurable scattered intensity. This result will further enable the...
Article
Full-text available
This work aimed to investigate a safer frother for coal flotation with achieving similar or better flotation performance, compared with the most common frother methyl isobutyl carbinol (MIBC) that caused some fire hazards in the past due to its low flash point (F.P. = 39 °C). Based on the higher flash points and low risk rating according to their s...
Article
Full-text available
This paper discusses the primary collector adsorption onto a sulphide mineral in mixed collector systems to further understand its adsorption mechanism. UV-Vis measurements were performed to identify the primary collector concentration adsorbed on pyrite, and the adsorption kinetics under different conditions were compared to distinguish their diff...
Article
Full-text available
This study aimed to investigate the sulphidization-flotation of nickel oxide. Sulphidization was conducted before froth flotation to convert the surface of nickel oxide to nickel sulphide. Key variables considered were type of sulphidization reagent, sulphidization Eh, time of sulphidization, and flotation Eh. Ammonium sulphide ((NH4)2S) was more e...
Article
Full-text available
This study aimed to investigate the sulphidization-flotation of nickel oxide. Sulphidization was conducted before froth flotation to convert the surface of nickel oxide to nickel sulphide. Key variables considered were type of sulphidization reagent, sulphidization Eh, time of sulphidization, and flotation Eh. Ammonium sulphide ((NH4)2S) was more e...
Article
Case studies of nickel mines in New Caledonia revealed significant differences among mining sites even though the mines host the same type of nickel laterite ore deposit and employ the same open-cut mining method. The intensity of land use change was evaluated as the area of land use change per unit of metal contained in extracted ores. Among the s...
Article
Full-text available
This paper reviews two separation methods applying two-step two-liquid flotation for recovering ultra-fine rare earth fluorescent powders (i.e., red, green, and blue). The paper aims to extract the science behind separation by two-liquid flotation, and to provide resulting engineering tips for material recycling. Two-liquid flotation, also called l...
Article
This paper aims to summarize the series of investigations on coupling suspension yield stress and DLVO (Derjaguin-Landau-Verwey-Overbeek) forces, i.e. van der Waals and electrical double layer forces. This summary provides a better understanding of the basic phenomena associated, historical development and current status of this useful coupling, an...
Article
Full-text available
Nano bubbles are prepared by using a pressurized pump or fine ceramics in water or oil. The prepared nano bubbles are stable for more than several days. Nano emulsion (w/o type) is prepared by mixing oil, water and surfactant with homogenizer and stable more than several months. The prepared bubble and emulsion size distribution in liquid is usuall...
Article
Full-text available
This study aimed to investigate the applicability of coal-oil gold agglomeration (CGA) assisted flotation to recover gold from a refractory ore. The ore with the grade of 2-5 g/t was tested with the CGA-flotation process in six different size fractions from 38 to 300 urn using different collector types and dosages. In addition, the flotation withou...
Chapter
There has been much attention focused on the utilization of complex ores due to decrease in the accessibility of high-grade and easily extractable ores. In order to maintain the sustainable use of mineral resources, the effective beneficiation of complex ores is urgently required. It can be achieved with a strong assist from mineralogical and parti...
Conference Paper
This paper discusses the primary collector adsorption onto a sulphide mineral in mixed collector systems to understand its adsorption mechanism. UV-vis measurements were performed to identify the primary collector concentration adsorbed on pyrite, and the adsorption kinetics under different conditions were compared to distinguish their difference b...
Conference Paper
The different types of nano to submicron particles, which are well-dispersed nano particles, coagulated nano particles or settled submicron particles, have been measured by the interactive force apparatus (IFA). The information is very useful for mineral processing treatment. The IFA can measure the particle size distribution in low to high concent...
Chapter
This chapter aims to summarize the investigation on the selective dispersion and characterization of particle mixture systems in concentrated suspensions to better understand their current status and to extract the useful information for advanced particle processing. Dispersion of fine particles is a challenging problem. The first difficulty is to...
Article
This paper aims to summarize recent investigations into the dispersion of fine particles, and the characterization of their interactions, in concentrated suspensions. This summary will provide a better understanding of the current status of this research, and will provide useful feedback for advanced particle processing. Such processes include the...