Electronic Waste Analysis and Characterization Study: Management input for Highly Urbanized Cities

Abstract Mineralogical and textural variability of ores from different sources commonly leads to processing inefficiencies, particularly when a processing plant is designed to treat ore from a single source (i.e. ore of a relatively uniform composition). The bulk of the Witwatersrand ore in the Klerksdorp goldfield, processed at the AngloGold Ashanti Great Noligwa treatment plant, is derived from the Vaal Reef (>90%), with a comparatively small contribution obtained from the Crystalkop Reef (or C-Reef). Despite the uneven contribution, it is of critical importance to ensure that the processing parameters are optimized for the treatment of both the Vaal and C-Reefs. This paper serves to document the results of a geometallurgical study of the C-Reef at the Great Noligwa gold mine in the Klerksdorp goldfield of South Africa, with the primary aim of assessing the suitability of the processing parameters that are in use at the Great Noligwa plant. The paper also draws comparisons between the C-Reef and the Vaal Reef A-facies (Vaal Reef) and attempts to explain minor differences in the recovery of gold and uranium from these two sources. Three samples of the C-Reef were collected in-situ from the underground operations at Great Noligwa mine for mineralogical analyses and metallurgical tests. Laboratory-scale leach tests for gold (cyanide) and uranium (sulphuric acid) were carried out using dissolution conditions similar to that in use at the Great Noligwa plant, followed by further diagnostic leaching in the case of gold. The gold in the ore was found to be readily leachable with recoveries ranging from 95% to 97% (as opposed to 89% to 93% for the Vaal Reef). Additional recoveries were achieved in the presence of excess cyanide (96% to 98%). The recovery of uranium varied between 72% and 76% (as opposed to 30% to 64% for the Vaal Reef), which is substantially higher than predicted, given the amount of brannerite in the ore, which is generally regarded as refractory. Thus, the higher uranium recoveries from the C-Reef imply that a proportion of the uranium was recovered by the partial dissolution of brannerite. As the Vaal Reef contain high amounts of chlorite (3% to 8%), which is an important acid consumer, it is considered likely that this could have reduced the effectiveness of the H2SO4 leach in the case of the ore of the Vaal Reef. Since the gold and uranium recoveries from the C-Reef were higher than the recoveries from the Vaal Reef, the results demonstrate that the processing parameters used for treatment of the Vaal Reef are equally suited to the treatment of the C-Reef. Moreover, small processing modifications, such as increased milling and leach retention times, may well increase the recovery of gold (particularly when e.g. coarse gold, or unexposed gold, is present).

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Modeling Complex Systems for Organizational Analysis: Towards Understanding the Object of Study/Management Intervention

SSRN Electronic Journal ◽

10.2139/ssrn.1263448 ◽

2006 ◽

Author(s):

Andres Guillermo Hernandez

Keyword(s):

Complex Systems ◽

Organizational Analysis ◽

Management Intervention ◽

Study Management ◽

Object Of Study

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Sustainable roll-to-roll manufactured multi-layer smart label

The International Journal of Advanced Manufacturing Technology ◽

10.1007/s00170-021-07640-z ◽

2021 ◽

Author(s):

Liisa Hakola ◽

Elina Jansson ◽

Romain Futsch ◽

Tuomas Happonen ◽

Victor Thenot ◽

...

Keyword(s):

Electronic Waste ◽

Near Field ◽

Colour Change ◽

Pilot Scale ◽

Printed Antennas ◽

Free Paper ◽

Roll To Roll ◽

Final Yield ◽

Smart Label ◽

Dark Blue

AbstractSustainability in electronics has a growing importance due to, e.g. increasing electronic waste, and global and European sustainability goals. Printing technologies and use of paper as a substrate enable manufacturing of sustainable electronic devices for emerging applications, such as the multi-layer anti-counterfeit label presented in this paper. This device consisted of electrochromic display (ECD) element, NFC (near field communication) tag and circuitry, all fully roll-to-roll (R2R) printed and assembled on plastic-free paper substrate, thus leading to a sustainable and recyclable device. Our setup uses harvested energy from HF field of a smartphone or reader, to switch an electrochromic display after rectification to prove authenticity of a product. Our novelty is in upscaling the manufacturing process to be fully printable and R2R processable in high-throughput conditions simulating industrial environment, i.e. in pilot scale. The printing workflow consisted of 11 R2R printed layers, all done in sufficient quality and registration. The printed antennas showed sheet resistance values of 32.9±1.9 mΩ/sq. The final yield was almost 1500 fully printed devices, and in R2R assembly over 1400 labels were integrated with 96.5% yield. All the assembled tags were readable with mobile phone NFC reader. The optical contrast (ΔE*) measured for the ECDs was over 15 for all the printed displays, a progressive switching time with a colour change visible in less than 5 s. The smart tag is ITO-free, plastic-free, fully printed in R2R and has a good stability over 50 cycles and reversible colour change from light to dark blue.

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Studies on the Content of Selected Technology Critical Elements (Germanium, Tellurium and Thallium) in Electronic Waste

Materials ◽

10.3390/ma14133722 ◽

2021 ◽

Vol 14 (13) ◽

pp. 3722

Author(s):

Joanna Willner ◽

Agnieszka Fornalczyk ◽

Magdalena Jablonska-Czapla ◽

Katarzyna Grygoyc ◽

Marzena Rachwal

Keyword(s):

Solar Cell ◽

New Technologies ◽

Electronic Waste ◽

Quantitative Composition ◽

Icp Oes ◽

Electronic Components ◽

Critical Elements ◽

Weee Recycling ◽

Icp Ms ◽

And Migration

The article draws attention to the problem of the presence of metals: germanium (Ge), tellurium (Te), thallium (Tl), and others (Cd, Ba, Co, Mn, Cr, Cu, Ni, Pb, Sr, and Zn) in selected waste of electrical and electronic equipment (WEEE). As a result of the growing demand for new technologies, the global consumption of TECs has also been increasing. Thus, the amount of metals in circulation, of which the impacts on the environment have not yet been fully understood, is constantly increasing. Due to the low content of these metals in WEEE, they are usually ignored during e-waste analyses. The main aim of this study was to determine the distribution of Ge, Te, and Tl (and other elements) in ground sieve fractions (1.0, 0.5, 0.2, and 0.1 mm) of selected electronic components (solar lamps, solar cell, LED TV screens, LCD screens, photoresistors, photodiodes, phototransistors) and to determine the possible tendency of the concentrations of these metals in fractions. This problem is particularly important because WEEE recycling processes (crushing, grinding, and even collection and transport operations) can lead to dispersion and migration of TCE pollutants into the environment. The quantitative composition of e-waste was identified and confirmed by ICP-MS, ICP-OES and SEM-EDS, and XRD analyses. It was found that Ge, Te, and Tl are concentrated in the finest fractions of ground e-waste, together with Cd and Cr, which may favor the migration of these pollutants in the form of dust during storage and processing of e-waste.

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Brominated flame retardants (BFRs) in PM2.5 associated with various source sectors in southern China

Environmental Science Processes & Impacts ◽

10.1039/d0em00443j ◽

2021 ◽

Author(s):

qiqi li ◽

Tao Wang ◽

yuan zeng ◽

yun fan ◽

Shejun Chen ◽

...

Keyword(s):

Flame Retardants ◽

Southern China ◽

Electronic Waste ◽

Brominated Flame Retardants ◽

Waste Recycling ◽

Recycling Facilities

The present study investigated legacy and novel brominated flame retardants (BFRs) in atmospheric PM2.5 associated with various urban source sectors in a city and electronic waste (e-waste) recycling facilities in...

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