scholarly journals Characterizing the Urban Mine–Challenges of Simplified Chemical Analysis of Anthropogenic Mineral Residues

Resources ◽  
2019 ◽  
Vol 8 (3) ◽  
pp. 132 ◽  
Author(s):  
Mählitz ◽  
Løvik ◽  
Figi ◽  
Schreiner ◽  
Kuntz ◽  
...  
Keyword(s):  
Quality Assurance ◽  
Chemical Analysis ◽  
Lithium Ion ◽  
Reference Value ◽  
Spectral Lines ◽  
Internal Quality ◽  
Xrf Analysis ◽  
Analysis Methods ◽  
Mass Fractions ◽  
Wet Chemical

Anthropogenic mineral residues are characterized by their material complexity and heterogeneity, which pose challenges to the chemical analysis of multiple elements. However, creating an urban mine knowledge database requires data using affordable and simple chemical analysis methods, providing accurate and valid results. In this study, we assess the applicability of simplified multi-element chemical analysis methods for two anthropogenic mineral waste matrices: (1) lithium-ion battery ash that was obtained from thermal pre-treatment and (2) rare earth elements (REE)-bearing iron-apatite ore from a Swedish tailing dam. For both samples, simplified methods comprising ‘inhouse’ wet-chemical analysis and energy-dispersive Xray fluorescence (ED-XRF) spectrometry were compared to the results of the developed matrix-specific validated methods. Simplified wet-chemical analyses showed significant differences when compared to the validated method, despite proven internal quality assurance, such as verification of sample homogeneity, precision, and accuracy. Matrix-specific problems, such as incomplete digestion and overlapping spectra due to similar spectral lines (ICP-OES) or element masses (ICP-MS), can result in quadruple overestimations or underestimation by half when compared to the reference value. ED-XRF analysis proved to be applicable as semi-quantitative analysis for elements with mass fractions higher than 1000 ppm and an atomic number between Z 12 and Z 50. For elements with low mass fractions, ED-XRF analysis performed poorly and showed deviations of up to 90 times the validated value. Concerning all the results, we conclude that the characterization of anthropogenic mineral residues is prone to matrix-specific interferences, which have to be addressed with additional quality assurance measures.

scholarly journals Variability and Bias in Measurements of Metals Mass Fractions in Automobile Shredder Residue

Recycling ◽  
2019 ◽  
Vol 4 (3) ◽  
pp. 34 ◽  
Author(s):  
Løvik ◽  
Figi ◽  
Schreiner ◽  
Rösslein ◽  
Widmer ◽  
...  
Keyword(s):  
Trace Metals ◽  
Chemical Analysis ◽  
Sample Preparation ◽  
Resource Potential ◽  
Shredder Residue ◽  
Automobile Shredder Residue ◽  
Mass Fractions ◽  
Systematic Effects ◽  
Wet Chemical ◽  
Good Agreement

The treatment of end-of-life vehicles generates large amounts of automobile shredder residue (ASR), a potential source of recycled metals. Reliable measurement methods are required to determine the composition of ASR and evaluate the resource potential. We reported on research undertaken to investigate bias and variability in the process of measuring trace metals in ASR. Two primary samples of shredder light fraction (SLF) underwent extensive physical sample preparation and chemical analysis. The samples were spiked to control random variations and systematic effects during physical sample preparation. Chemical analysis was conducted using wavelength-dispersive X-ray fluorescence spectrometry (WD-XRF), a fully validated wet-chemical analysis, and a wet-chemical analysis representing an “in-house” lab procedure. Physical sample preparation introduced deviations up to a factor of 2, likely due to preferential losses and heterogeneity. Deviations for WD-XRF measurements of elements were in the range +100%/−50%. In-house chemical analysis produced results that were in good agreement with validated results for Al, Fe and Sn, but led to biased results or high variability for Cd, Dy, La, Nd, Pb, Pd, Pt and Sb. To improve the chemical analysis of trace metals in SLF, we recommended reducing particle size to less than 0.1 mm before chemical analysis and using a larger number of repeated digestions.

Sector growth and symmetry of (F,OH) apatite from the Asio mine, Japan

1994 ◽  
Vol 58 (391) ◽  
pp. 307-314 ◽  
Author(s):  
Mizuhiko Akizuki ◽  
Hirotugu Nisidoh ◽  
Yasuhiro Kudoh ◽  
Tomohiro Watanabe ◽  
Kazuo Kurata
Keyword(s):  
Optical Properties ◽  
Crystal Growth ◽  
Electron Diffraction ◽  
Chemical Analysis ◽  
Growth Surface ◽  
Complete Disappearance ◽  
X Ray ◽  
Solid Crystal ◽  
Wet Chemical ◽  
Growth Features

AbstractA study of apatite crystals from the Asio mine, Japan, showed sectoral texture related to the growth of the crystal, and with optically biaxial properties within the sectors. Wet chemical analysis gave a composition Ca5(PO4)3(F0.64,OH0.38,Cl0.01)1.03 for the specimen.Additional diffraction spots were not observed in precession and oscillation X-ray photographs and electron diffraction photographs. Since the internal textures correlate with the surface growth features, it is suggested that the internal textures and the unusual optical properties were produced during nonequilibrium crystal growth. The fluorine/hydroxyl sites in hexagonal apatite are symmetrically equivalent in the solid crystal but, at a growth surface, this equivalence may be lost, resulting in a reduction of crystal symmetry. Heating of the apatite to about 850°C results in the almost complete disappearance of the optical anomalies due to disordering, which may be related to the loss of hydroxyl from the crystal.

scholarly journals Conceptualising External and Internal Quality Assurance in Higher Education: A Pragmatist Perspective

2016 ◽  
Vol 2 ◽  
Author(s):  
Francis Ansah
Keyword(s):  
Higher Education ◽  
Quality Assurance ◽  
Current Understanding ◽  
Education Quality ◽  
Internal Quality ◽  
Practical Relevance ◽  
Higher Education Quality ◽  
Internal Quality Assurance ◽  
The Relationship ◽  
Education Quality Assurance

The traditional tension between external and internal quality assurance implementation in higher education appears to be declining, based on a rethinking of the relationship between the two concepts. Although there are quality assurance agencies that still consider external and internal quality assurance as separate entities, most quality assurance agencies now regard the two concepts as complementary. In this paper, a case is put that the present rethinking of external and internal quality assurance in most higher education settings is guided by pragmatism, but not explicitly acknowledged in the literature. For a better appreciation of pragmatists’ influence on the current understanding of the relationship between external and internal quality assurance in higher education, this paper provides a further pragmatist conceptualisation of the two concepts to enhance stakeholders’ appreciation of employing a pragmatist approach to quality assurance practices in higher education. The conceptualisation is done through a pragmatist analysis of selected international accounts on higher education quality assurance. The paper concludes that pragmatism helps to understand external and internal quality assurance as nested concepts with reciprocities of accountability and improvement roles, and influences which call for alignment of perspectives through negotiations and settlements in order to focus on their practical relevance for implementation in higher education. La tension traditionnelle entre l’implémentation de systèmes d’assurance qualité interne et externe dans l’enseignement supérieur semble s’affaiblir grâce à la reconsidération de la relation entre ces deux concepts. Bien qu’il existe des agences d’assurance qualité qui continuent à considérer les assurances qualité interne et externe comme deux entités distinctes, la plupart des agences considèrent désormais qu’elles sont complémentaires. Cet article soutient que la nouvelle manière de penser les assurances qualité interne et externe dans l’enseignement supérieur est guidée par un souci de pragmatisme mais est encore peu reconnue dans la littérature. Pour mieux apprécier l’influence des pragmatistes sur la compréhension actuelle de la relation entre les assurances qualité interne et externe, cet article offre une conceptualisation pragmatique approfondie de ces deux concepts dans le but d’augmenter l’appréciation des parties prenantes pour l’utilisation d’une telle approche. La conceptualisation proposée provient d’une analyse pragmatique d’un choix d’expériences internationales en matière d’assurance qualité pour l’enseignement supérieur. En conclusion, cet article affirme que le pragmatisme aide à comprendre les assurances qualité interne et externe comme des concepts imbriqués qui ont des rôles réciproques en ce qui concerne la responsabilisation du système et son amélioration. Ces rôles ainsi que l’influence exercée par ces deux types d’assurance qualité requièrent des négociations et accords, pour s’accorder sur les perspectives et pouvoir ensuite se concentrer pleinement sur la pertinence pratique de leur implémentation dans les systèmes d’enseignement supérieur. 

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