scholarly journals Surface Mechanism of Fe3+ Ions on the Improvement of Fine Monazite Flotation With Octyl Hydroxamate as the Collector

2021 ◽  
Vol 9 ◽  
Author(s):  
Qingzhu Zheng ◽  
Yunlou Qian ◽  
Dan Zou ◽  
Zhen Wang ◽  
Yang Bai ◽  
...  
Keyword(s):  
Zeta Potential ◽  
Fluorescence Spectrum ◽  
Photoelectron Spectroscopy ◽  
Froth Flotation ◽  
Research Direction ◽  
Surface Hydrophobicity ◽  
Coarse Fraction ◽  
Theory And Practice ◽  
Schematic Model ◽  
Hydrophobic Adsorption

Froth flotation of fine minerals has always been an important research direction in terms of theory and practice. In this paper, the effect and mechanism of Fe3+ on improving surface hydrophobicity and flotation of fine monazite using sodium octyl hydroxamate (SOH) as a collector were investigated through a series of laboratory tests and detection measurements including microflotation, fluorescence spectrum, zeta potential, and X-ray photoelectron spectroscopy (XPS). Flotation tests have shown that fine monazite particles (−26 + 15 μm) cannot be floated well with the SOH collector compared to the coarse fraction (−74 + 38 μm). However, adding a small amount of Fe3+ to the pulp before SOH can significantly improve the flotation of fine monazite. This is because the addition of Fe3+ promotes the adsorption of SOH and greatly improves the hydrophobicity of the monazite surface. This can result in the formation of a more uniform and dense hydrophobic adsorption layer, as shown by the fluorescence spectrum and zeta potential results. From the XPS results, Fe3+ reacts with surface O atoms on the surface of monazite to form a monazite–Osurf–Fe group that acts as a new additional active site for SOH adsorption. A schematic model was also proposed to explain the mechanism of Fe3+ for improving surface hydrophobicity and flotation of fine monazite using octyl hydroxamate as a collector. The innovative point of this study is using a simple reagent scheme to float fine mineral particles rather than traditional complex processes.

scholarly journals A Comparative Study on the Wettability of Two Coal Samples during Deep Burial Metamorphism

2020 ◽  
Vol 2020 ◽  
pp. 1-7 ◽  
Author(s):  
Guochao Yan ◽  
Longjian Bai ◽  
Jianping Feng ◽  
Zhiqiang Zhang
Keyword(s):  
Contact Angle ◽  
Zeta Potential ◽  
Photoelectron Spectroscopy ◽  
Coal Sample ◽  
Surface Hydrophobicity ◽  
Dlvo Theory ◽  
Particle Collision ◽  
Deep Burial ◽  
Coal Particles ◽  
Wetting Process

In order to investigate the effect of deep burial metamorphism on the wettability of coal during deep burial metamorphism, a superficial coal sample (∼90 m) and a deep coal sample (∼490 m) collected from two main mining seams were selected to simulate the deep burial metamorphism process. The wettability of two coal samples during deep burial metamorphism was investigated by X-ray photoelectron spectroscopy (XPS), FTIR, zeta potential, and contact angle measurements. Besides, comprehensive DLVO interaction analyses between two coal samples from different mining depths were carried out through the zeta potentials measurements under different pH values. The XPS results demonstrate that the content of surface oxygen atom and oxygen-containing functional group for superficial coal tends to be higher than that of deep coal. The FTIR results indicate that the peak intensity of oxygen-containing functional groups for the superficial is higher than that of deep coal, implying the stronger surface hydrophobicity of deep coal compared to superficial coal. The contact angle of superficial coal is lower than that of deep coal. The zeta potential and DLVO theory analyses of superficial particles and deep coal particles indicate that deep burial metamorphism process might be favorable for bubble-particle collision and attachment, while might be unfavorable for the wetting process oppositely. Based on the surface chemistry characterization and theory analyses, this study is expected to give a theoretical insight into the efficient processing or dedusting process of coals experiencing different deep burial metamorphism processes in the future.

Central government patronage, donor aid, and budget performance in local government: testing a mediation effect

2016 ◽  
Vol 28 (2) ◽  
pp. 139-170 ◽  
Author(s):  
Paul Onyango-Delewa
Keyword(s):  
Local Government ◽  
Fiscal Federalism ◽  
Central Government ◽  
Research Direction ◽  
Theory And Practice ◽  
Mediation Effect ◽  
Future Research ◽  
Future Research Direction ◽  
Mixed Methods Design ◽  
Donor Agencies

Drawing on network and fiscal federalism theories, we investigated central government patronage and donor aid as antecedents of budget performance in local government (LG). A mixed methods design with data collected from 18 LGs, two ministries, and four donor agencies in Uganda was employed. Results revealed that both central government patronage and donor aid predict budget performance. Moreover, autonomy does not mediate the interactions as initially hypothesized. Implications for theory and practice are discussed and future research direction is provided.

scholarly journals Review of the Main Factors Affecting the Flotation of Phosphate Ores

Minerals ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1109
Author(s):  
Manar Derhy ◽  
Yassine Taha ◽  
Rachid Hakkou ◽  
Mostafa Benzaazoua
Keyword(s):  
Zeta Potential ◽  
Aqueous Solutions ◽  
Treatment Process ◽  
Froth Flotation ◽  
Main Constituent ◽  
Full Understanding ◽  
Factors Affecting ◽  
Froth Stability ◽  
Main Factors ◽  
Phosphate Ores

The way to successfully upgrade a phosphate ore is based on the full understanding of its mineralogy, minerals surface properties, minerals distribution and liberation. The conception of a treatment process consists of choosing the proper operations with an adequate succession depending on the ore properties. Usually, froth flotation takes place in phosphate enrichment processes, since it is cheap, convenient, and well developed. Nevertheless, it is a complex technique as it depends on the mineral’s superficial properties in aqueous solutions. Aspects such as wettability, surface charge, zeta potential, and the solubility of minerals play a basic role in defining the flotation conditions. These aspects range from the reagents type and dosage to the pH of the pulp. Other variables namely particles size, froth stability, and bubbles size play critical roles during the treatment, as well. The overall aim is to control the selectivity and recovery of the process. The following review is an attempt to add to previous works gathering phosphate froth flotation data. In that sense, the relevant parameters of phosphate ores flotation are discussed while focusing on apatite, calcite, dolomite, and quartz as main constituent minerals.

Adsorption and zeta potential studies relevant to hematite ore reverse froth flotation

2012 ◽  
Vol 29 (3) ◽  
pp. 148-155
Author(s):  
Wentian Jiang ◽  
Chenglin Sun ◽  
Xu Yang
Keyword(s):  
Zeta Potential ◽  
Froth Flotation ◽  
Hematite Ore

scholarly journals Activation Mechanism of Lead Ions in Perovskite Flotation with Octyl Hydroxamic Acid Collector

Minerals ◽  
2018 ◽  
Vol 8 (8) ◽  
pp. 341 ◽  
Author(s):  
Yu Zheng ◽  
Yating Cui ◽  
Weiqing Wang
Keyword(s):  
Zeta Potential ◽  
Photoelectron Spectroscopy ◽  
Hydroxamic Acid ◽  
Relative Content ◽  
Lead Ions ◽  
Activation Mechanism ◽  
X Ray ◽  
Ft Ir ◽  
Acidic Conditions ◽  
Ir Analysis

The activation mechanism of lead ions (Pb2+) in perovskite flotation with an octyl hydroxamic acid collector was systematically investigated using microflotation experiments, zeta-potential measurements, adsorption tests, Fourier transform infrared (FT-IR) analysis, and X-ray photoelectron spectroscopy (XPS) analysis. The results of microflotation experiments and adsorption tests indicate that the presence of Pb2+ can promote the adsorption of octyl hydroxamic acid (OHA) on the perovskite surface and enhance the flotability of perovskite under weakly acidic conditions. The maximum recovery of 79.62% was obtained at pH 6.5 in the presence of Pb2+, and the maximum recovery of 57.93% was obtained at pH 5.7 without Pb2+. At pHs below 7, lead species are mainly present as Pb2+ and PbOH+ in the solution; besides this, the relative content of titanium increases on the perovskite surface. The adsorption of Pb2+ and PbOH+ on the perovskite surface makes the zeta-potential of perovskite shift positively, and increases the number of activated sites on the perovskite surface. FT-IR and XPS analyses confirm that OHA chemisorbs on the surface of Pb2+-activated perovskite and forms hydrophobic Pb-OHA complexes, which improve the flotability of perovskite.

The Use of X-Ray Photoelectron Spectroscopy for the Study of Oral Streptococcal Cell Surfaces

1997 ◽  
Vol 11 (4) ◽  
pp. 388-394 ◽  
Author(s):  
H.C. Van Der Mei ◽  
H.J. Busscher
Keyword(s):  
Cell Surface ◽  
Photoelectron Spectroscopy ◽  
Surface Composition ◽  
Cell Surface Hydrophobicity ◽  
Surface Hydrophobicity ◽  
Contact Angles ◽  
Microbial Cell ◽  
Cell Surfaces ◽  
Water Contact ◽  
X Ray

Physicochemical and structural properties of microbial cell surfaces play an important role in their adhesion to surfaces and are determined by the chemical composition of the outermost cell surface. Many traditional methods used to determine microbial cell wall composition require fractionation of the organisms and consequently do not yield information about the composition of the outermost cell surface. X-ray photoelectron spectroscopy (XPS) measures the elemental composition of the outermost cell surfaces of micro-organisms. The technique requires freeze-drying of the organisms, but, nevertheless, elemental surface concentration ratios of oral streptococcal cell surfaces with peritrichously arranged surface structures showed good relationships with physicochemical properties measured under physiological conditions, such as zeta potentials. Isoelectric points ap-peared to be governed by the relative abundance of oxygen- and nitrogen-containing groups on the cell surfaces. Also, the intrinsic microbial cell-surface hydrophobicity by water contact angles related to the cell-surface composition as by XPS and was highest for strains with an elevated isoelectric point. Inclusion of elemental surface compositions for tufted streptococcal strains caused deterioration of the relationships found. Interestingly, hierarchical cluster analysis on the basis of the elemental surface compositions revealed that, of 36 different streptococcal strains, only four S. rattus as well as nine S. mitis strains were located in distinct groups, well separated from the other streptococcal strains, which were all more or less mixed in one group.

scholarly journals The Auxiliary Effect of Copper Ions on the Depressant Effect of Sodium Thioglycolate in Chalcopyrite Flotation

Minerals ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 157
Author(s):  
Chonghui Zhang ◽  
Tingshu He ◽  
Wei Chen ◽  
Xianzhong Bu ◽  
Sen Wang ◽  
...  
Keyword(s):  
Zeta Potential ◽  
Photoelectron Spectroscopy ◽  
Active Sites ◽  
Copper Ions ◽  
Depressant Effect ◽  
X Ray ◽  
Adsorption Sites ◽  
Effect Of Copper ◽  
Adsorption Layers ◽  
Hydrophobic Substance

Sodium thioglycolate is a chalcopyrite depressant, but its depressant effect is weak. The paper investigated the effect of CuSO4 on the depressant performance of sodium thioglycolate towards chalcopyrite through flotation tests, Zeta potential measurements, X-ray photoelectron spectroscopy (XPS) analyses and Fourier-transform infrared (FTIR) spectra measurements. It was found that copper ions could improve the depressant effect of sodium thioglycolate on chalcopyrite. The results showed that copper ions could adsorb on the surface of chalcopyrite and form mixed copper sulfide and cupric oxides/hydroxides adsorption layers. As a result, the mineral composition on the chalcopyrite surface was changed. With sodium thioglycolate treatment, the Zeta potential and the adsorption sites of chalcopyrite surface were both increased, and the hydrophobic substance Sn2−/S0 concentration was decreased. The electrostatic repulsion of chalcopyrite surface with sodium thioglycolate was also decreased, which made the sodium thioglycolate interact with chalcopyrite more easily. The more active sites could adsorb more sodium thioglycolate, which improved the hydrophilia of chalcopyrite. At the same time, the decrease of Sn2−/S0 concentration could further improve the hydrophilia of chalcopyrite. The results show that the copper ions could exhibit auxiliary effect with sodium thioglycolate and could further enhance the depressant effect of sodium thioglycolate on the chalcopyrite flotation. This paper provides new insights into the depression of chalcopyrite flotation by sodium thioglycolate.

scholarly journals Towards a sociomaterial approach to inter-organizational boundaries: How information systems elicit relevant knowledge in government outsourcing

2020 ◽  
pp. 026839622093449
Author(s):  
Annalisa Pelizza
Keyword(s):  
Information Systems ◽  
Research Direction ◽  
Theory And Practice ◽  
Database Integration ◽  
It Projects ◽  
Organizational Boundaries ◽  
The Public ◽  
First Case ◽  
Macro Scale ◽  
Analytical Tools

This article furthers a sociomaterial framework to examine inter-organizational boundaries in government IT projects. It engages in a dialogue with the practice theory-based approach to boundary spanning and utilizes analytical tools and epistemologies drawn from the social studies of technology. It aims to contribute to a situated, material understanding of inter-organizational boundaries. We argue that boundaries in outsourcing relationships can be de facto enacted through definitions of what counts as relevant knowledge. Information systems have a key role in eliciting such definitions, thus establishing knowledge asymmetries and regimes of inclusion and exclusion. The article responds to the call to value the role of artefacts in IT research. Furthermore, it eventually shows that understanding knowledge asymmetries triggered at the micro-level of information systems can help to examine macro-scale transformations between the public and the private sectors. To illustrate the framework, two ethnographic case studies of governmental IT projects are discussed. The first case concerns a permit and licence submission service in Italy. The second case analyses a 20-year-long database integration carried on at the Dutch land registry. In the first case, information systems made relevant a form of knowledge developed by contractors; in the second case, the integration process valued knowledge developed in-house. Three sets of implications are drawn for the theory and practice of inter-organizational IT projects. To conclude, the article focuses on inter-organizational boundaries involving the public and the private sectors and foresees a novel interdisciplinary research direction at the confluence of information systems and political studies.

scholarly journals A Review of Flotation Separation of Mg Carbonates (Dolomite and Magnesite)

Minerals ◽  
2018 ◽  
Vol 8 (8) ◽  
pp. 354 ◽  
Author(s):  
Darius Wonyen ◽  
Varney Kromah ◽  
Borbor Gibson ◽  
Solomon Nah ◽  
Saeed Chelgani
Keyword(s):  
Particle Size ◽  
Adverse Effects ◽  
Zeta Potential ◽  
Separation Efficiency ◽  
Froth Flotation ◽  
Surface Characteristics ◽  
Economic Viability ◽  
Ore Bodies

It is well documented that flotation has high economic viability for the beneficiation of valuable minerals when their main ore bodies contain magnesium (Mg) carbonates such as dolomite and magnesite. Flotation separation of Mg carbonates from their associated valuable minerals (AVMs) presents several challenges, and Mg carbonates have high levels of adverse effects on separation efficiency. These complexities can be attributed to various reasons: Mg carbonates are naturally hydrophilic, soluble, and exhibit similar surface characteristics as their AVMs. This study presents a compilation of various parameters, including zeta potential, pH, particle size, reagents (collectors, depressant, and modifiers), and bio-flotation, which were examined in several investigations into separating Mg carbonates from their AVMs by froth flotation.

scholarly journals Exploring the Impacts of Industry 4.0 from a Macroscopic Perspective

2019 ◽  
Vol 1 (1) ◽  
pp. 2111-2120
Author(s):  
Rongyan Zhou ◽  
Julie Le Cardinal
Keyword(s):  
Industry 4.0 ◽  
Research Direction ◽  
Status Quo ◽  
Theory And Practice ◽  
Practical Application ◽  
Great Opportunity ◽  
Leading Role ◽  
The Status ◽  
New Situation

AbstractIndustry 4.0 is a great opportunity and a great challenge for enterprises. Nowadays, how to adjust the strategy according to the new situation to deal with the opportunities and challenges brought by Industry 4.0 is a hot topic. The paper investigates what is Industry 4.0 and compares the different fourth industry revolution programs in various countries and takes advantage of bibliometric to investigate which technologies play an important role in Industry 4.0. What is more, the status quo, challenges and development directions faced in various fields in the industrial 4.0 era are elaborated. The paper not only combs the research direction for researchers, but also presents the status quo of practical application for enterprises. The paper contributes to showing a leading role for theory and practice of industry 4.0.

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