Electronic Waste and Existing Processing Routes: A Canadian Perspective

Electrical and electronic products have become an integral part of the current economy and, with the development of newer technologies, the life span of these products are getting shorter. As a consequence, the volume of electronic waste is increasing drastically around the globe. With the implementation of new rules, regulations, and policies by the government, the landfilling of electronic waste has been reduced. The presence of valuable metals in the e-waste stream provides a major economic benefit for recycling industries but, due to the presence of hazardous materials, a proper recycling technique is required prior to the disposal of the e-waste. The total e-waste generated in Canada was 725 kt in 2014. There are several organizations currently working in various provinces to deal with the collection and recycling of e-waste. These organizations collected nearly 20% of the total e-waste generated in 2014. The collection rate for e-waste can be boosted by increasing awareness and by creating more centers to collect all kinds of e-waste. The collected e-waste is processed at local processing facilities mostly dealing with dismantling and hazardous material removal processes and then shipping the remaining material to a central location for subsequent processing.Applied Science, Faculty ofMining Engineering, Keevil Institute ofReviewedFacult

Assessment of Sortability Using a Dual-Energy X-ray Transmission System for Studied Sulphide Ore

In hard rock mining, sensor-based sorting can be applied as a pre-concentration method before the material enters the mill. X-ray transmission sensors have been explored in mining since 1972. Sorting ore of acceptable grade and waste material before processing at the mill can reduce the amount of tailings per unit of valuable metal in the mining operation and have many economic benefits. Ore samples used in this paper are from a polymetallic carbonate replacement deposit (gold-silver-lead-zinc sulphide) in Southeast Europe. This paper focuses on how the Dual-Energy X-ray Transmission (DE-XRT) data is generated and used for ore characterization and sortability for this sulphide ore. The method used in the DE-XRT analysis in this project is based on the dual-material decomposition method, which is used in the medical industry for radiology. This technique can distinguish sulphides from non-sulphides. However, the correlation developed between the DE-XRT response and the metal content is lacking. As a result, the DE-XRT response can only classify the material effectively but cannot reliably predict the metal content.Applied Science, Faculty ofMining Engineering, Keevil Institute ofReviewedFacult

Micro-FTIR analysis to study the change in surface chemistry after addition of collectors and their effect on coal hydrophobicity

In this study, the micro-FTIR analysis was used to investigate in-situ surface properties of coal, and was directly correlated to coal hydrophobicity, as measured by the contact angle before and after the addition of collectors, to understand their suitability for flotation. Three different collectors, diesel, pine needle oil and dodecyl trimethyl ammonium bromide (DTAB) were tested. The micro-FTIR technique provided a semi-quantitative analysis of functional groups present on the coal surface exactly where the contact angle was measured and provided a visualization of collector adsorption on specific areas of coal and associated changes in coal surface properties. This analysis could lead to a smarter way of using process design in terms of reagent selection for coal flotation to obtain a product of desired petrographic composition, which would especially be useful for coking coals. This study presents a work in progress for developing a procedure for a quick pre-selection of collectors for coal flotation based on coal surface properties

Selection of reagents based on surface chemistry as derived from micro-FTIR mapping of coal surface to facilitate selectivity in coal flotation

In this study, the micro-FTIR analysis was used to investigate in-situ surface properties of coal and its components (macerals) and these were directly correlated to the coal hydrophobicity as measured by the contact angle before and after reagent addition to understand the suitability of the reagent for flotation. The micro-FTIR technique can provide a semi-quantitative analysis of the chemical functional groups on coal surface, exactly where the contact angle is being measured. Selected functional groups and their ratios that provide information about aromaticity, the contribution of oxygenated groups, and aliphaticity are used to evaluate the reactivity between reagents and various coal components. The observations made in relation to the susceptibility of some reagents towards certain coal components should lead the way to a smarter way of using process design in terms of reagents selection for coal flotation.Applied Science, Faculty ofNon UBCMining Engineering, Keevil Institute ofUnreviewedFacultyResearche

Surface Chemical Heterogeneity of Low Rank Coal Characterized by Micro-FTIR and Its Correlation with Hydrophobicity

Micro-Fourier transform infrared (micro-FTIR) spectroscopy was used to correlate the surface chemistry of low rank coal with hydrophobicity. Six square areas without mineral impurities on low rank coal surfaces were selected as testing areas. A specially-designed methodology was applied to conduct micro-FTIR measurements and contact angle tests on the same testing area. A series of semi-quantitative functional group ratios derived from micro-FTIR spectra were correlated with contact angles, and the determination coefficients of linear regression were calculated and compared in order to identify the structure of the functional group ratios. Finally, two semi-quantitative ratios composed of aliphatic carbon hydrogen, aromatic carbon hydrogen and two different types of carbonyl groups were proposed as indicators of low rank coal hydrophobicity. This work provided a rapid way to predict low rank coal hydrophobicity through its functional group composition and helped us understand the hydrophobicity heterogeneity of low rank coal from the perspective of its surface chemistry.Applied Science, Faculty ofNon UBCMining Engineering, Keevil Institute ofReviewedFacult

A systematic experimental study on gold recovery from electronic waste using selective ammonium persulfate oxidation

This paper presents a systematic approach on gold recovery from electronic waste (e-waste) using ammonium persulfate. This process was developed as a response to the lack of hydrometallurgical systems capable of separating gold from its metallic substrate without material grinding, with minimum formation of pollutants, and achieving a lower reaction time. Computer memory boards, electronic processors and electronic pins and contacts were analyzed to determinate base metals (Ni, Fe, Cu) and gold (Au) using microwave plasma atomic emission spectroscopy (MP-AES). An aqueous commercial grade ammonium persulfate with oxygen and pressure was used to produce the persulfate anion (S₂O₈²-) and the oxidative sulfate ion (SO₄²-), which partially oxidized and leached the base metals breaking the Au-Ni-Fe-Cu bonds and allowing gold to be recovered in its original non-leaching state. The influence of the oxidative parameters was evaluated using full factorial (FF) and central composite designs (CCD) with response surface methodology (RSM) and first and second order models were developed. Using RSM allowed to obtain a faster recovery of gold, minimizing the agent consumption. The findings presented suggest that optimized quantities of ammonium persulfate, oxygen, pressure, temperature and liquid solid ratio could be used for selective oxidization of the base metals and to extract more than 96% of gold from e-waste.Applied Science, Faculty ofNon UBCMining Engineering, Keevil Institute ofUnreviewedFacultyResearche

Improving the Energy Concentration in Waste Printed Circuit Boards Using Gravity Separation

Electronic waste is one the fastest growing waste streams in the world, and printed circuit boards (PCBs) are the most valuable fraction of this stream due to the presence of gold, silver, copper, and palladium. Printed circuit boards consist of approximately 30% metals and 70% non-metals. The non-metal fraction (NMF) is composed of 60–65% fiberglass and 35–40% organics, in the form of surface-mount plastics and epoxy resins in the printed circuit board laminates. The organics in the NMF provide a potential alternative source of energy, but hazardous flame retardants contained in epoxy resins and the presence of residual metals create challenges for utilizing this material for energy recovery. This research provides an evaluation of the energy content of printed circuit boards. Density-based separation was used to separate various components of the NMF to increase the energy content in specific density fractions while reducing the metal content. The result showed that the energy content before and after the removal of the metallic fraction from PCBs was 9 and 15 GJ/t, respectively. After the density-based separation of the NMF, the energy content in the lightest fraction increased to 21 GJ/t, while reducing the concentration of the hazardous flame retardants. The contents of the hazardous flame retardants and residual metal were analyzed, to evaluate the harmful effect of emissions produced from utilizing the NMF as an alternative feedstock in waste-to-energy applications.Applied Science, Faculty ofNon UBCMining Engineering, Keevil Institute ofReviewedFacult