A Comparison of Methods for the Characterisation of Waste-Printed Circuit Boards

Electronic waste is a growing waste stream globally. With 54.6 million tons generated in 2019 worldwide and with an estimated value of USD 57 billion, it is often referred to as an urban mine. Printed circuit boards (PCBs) are a major component of electronic waste and are increasingly considered as a secondary resource for value recovery due to their high precious and base metals content. PCBs are highly heterogeneous and can vary significantly in composition depending on the original function. Currently, there are no standard methods for the characterisation of PCBs that could provide information relevant to value recovery operations. In this study, two pre-treatments, smelting and ashing of PCB samples, were investigated to determine the effect on PCB characterisation. In addition, to determine the effect of particle size and element-specific effects on the characterisation of PCBs, samples were processed using four different analytical methods. These included multi-acid digestion followed by inductively coupled plasma optical emission spectrometry (ICP-OES) analysis, nitric acid digestion followed by X-ray fluorescence (XRF) analysis, multi-acid digestion followed by fusion digestion and analysis using ICP-OES, and microwave-assisted multi-acid digestion followed by ICP-OES analysis. In addition, a mixed-metal standard was created to serve as a reference material to determine the accuracy of the various analytical methods. Smelting and ashing were examined as potential pre-treatments before analytical characterisation. Smelting was found to reduce the accuracy of further analysis due to the volatilisation of some metal species at high temperatures. Ashing was found to be a viable pre-treatment. Of the four analytical methods, microwave-assisted multi-acid digestion offered the most precision and accuracy. It was found that the selection of analytical methods can significantly affect the accuracy of the observed metal content of PCBs, highlighting the need for a standardised method and the use of certified reference material.

Qualitative dynamics of waxy maize (Jikenuo 19) in different harvest times

Jikenuo 19 was used as experimental material, and six harvest times were set to study the effects of different harvest times on grain quality and gelatinization characteristics, so as to provide reference for the harvest time and quality improvement of waxy maize varieties. The results showed that when the harvest time was 27 days after pollination, the sensory and cooking quality score of Jikenuo 19 was the highest. Starch content increased with the delay of harvest time, while protein and soluble sugar content decreased. With the delay of harvest time, the peak viscosity, valley viscosity, final viscosity, disintegration value, recovery value and peak time all showed a trend of first increasing and then decreasing. Compared with starch and soluble sugar, the effect of protein in grain on gelatinization characteristics was higher. The present findings reveal that the best harvest time was 27 days after pollination, which will provide reference for determining the best harvest time and improving grain quality. Bangladesh J. Bot. 50(3): 987-992, 2021 (September) Special

Identifying and Evaluating Recirculation Strategies for Industry in the Nordic Countries

The manufacturing industry in the Nordic countries aims to include closing product and material loops to recover values in their circular economy strategies. Recirculating strategies for products and materials are required for existing products that are part of the stock and are also anticipated to be aligned with products designed for circularity and circular business models in the future. Options to capture value of discarded products are diverse and include reuse, remanufacturing and material recycling. The Circular Economy Integration in the Nordic Industry for enhanced sustainability and competitiveness (CIRCit) project developed a framework to guide decision makers in the industry on how to identify suitable treatments and subsequent use at the end of use or end of life of a product and how to select among different options. Factors considered in the assessment include technical feasibility, necessary efforts, networks of business partners, legal implications and overall sustainability aspects. Our empirical studies show great support for decision-makers in the value recovery of different products with different complexity levels. It is also concluded that the properties of products at their end of use are the main drivers behind selecting a proper recirculation strategy. This study contributes with an empirical evaluation and a consistent terminology framework for recirculation options. The general setup is relevant for the Nordic countries.

Assessment of Pre-Treatment Techniques for Coarse Printed Circuit Boards (PCBs) Recycling

Waste electrical and electronic equipment or e-waste generation has been skyrocketing over the last decades. This poses waste management and value recovery challenges, especially in developing countries. Printed circuit boards (PCBs) are mainly employed in value recovery operations. Despite the high energy costs of generating crushed and milled particles of the order of several microns, those are employed in conventional hydrometallurgical techniques. Coarse PCB pieces (of order a few centimetres) based value recovery operations are not reported at the industrial scale as the complexities of the internal structure of PCBs limit efficient metal and non-metal separation. Since coarse PCB particles’ pre-treatment is of paramount importance to enhance metal and non-metal separations, thermal, mechanical, chemical and electrical pre-treatment techniques were extensively studied. It is quite evident that a single pre-treatment technique does not result in complete metal liberation and therefore several pre-treatment flowsheets were formulated for coarse PCB particles. Thermal, mechanical and chemical pre-treatments integrated flowsheets were derived and such flowsheets are seldom reported in the e-waste literature. The potential flowsheets need to be assessed considering socio-techno-economic considerations to yield the best available technologies (BAT). In the wider context, the results of this work could be useful for achieving the United Nations sustainable development goals.

Pathway to Decarbonisation and Maximum Value Recovery for Remote Offshore Gas Fields

Gas developments are required to facilitate energy transition from carbon intensive energy to a sustainable balance of green and blue energy. The next decade will focus on exploiting gas fields globally to support this. A significant number of these fields are located in deepwater and /or are long distances from existing gas processing / LNG plants. Transporting large volumes of gas from remote gas fields over longer distances and in deeper waters remains technologically and economically challenging. Conventional and near-term development options include subsea compression, floating vessels with topside compression and pipeline tie-back to shore, or floating liquefied natural gas vessels. This paper and study are supported by The Oil & Gas Technology Centre (OGTC) and UK Oil and Gas Authority. It examines development options for a 200 km long 1700 m water depth tie back using integrated production modeling linked to power demands, along with installed steel tonnages. The Scope 1 and 2 emissions per unit of gas produced are analysed via a life cycle assessment using ISO 14044 as guidance for a long-distance gas tieback to the point of sale (inclusive of processing to sales specification). The major power intensive equipment used to develop these fields will be presented showing their proportion of the power consumption compared with the total; these include compression either onshore, offshore or subsea as well as the efficiency of the power generation devices in these environments. The paper will highlight the economics of each option and how varying the carbon price changes the commercial position of each option. The paper will show that by understanding what drives emissions, and how emissions relate to the amount of gas produced, that concept selection can drive upwards of 50% reduction in life cycle carbon emissions whilst improving project economic performance. This paper examines multiple innovative technologies, providing technology readiness of new concepts based on the benchmarked study focusing both economic and carbon emission aspects. Finally, the paper will show that better economic outcomes with the decarbonisation of gas gathering systems is technically possible and can be deployed subsea to help meet the energy transition and allow the development of remote and deeper gas fields.

Process development options for electronic waste fractionation to achieve maximum material value recovery

Revised legislation and bans on imports of waste electrical and electronic equipment (WEEE) into many Asian countries for treatment are driving the need for more efficient WEEE fractionation in Europe by expanding the capacity of treatment plants and improving the percentage recovery of materials of economic value. Data from a key stakeholder survey and consultation are combined with the results of a detailed literature survey to provide weighted matrix input into multi-criteria decision analysis calculations to carry out the following tasks: (a) assess the relative importance of 12 process options against the 6 industry-derived in-process economic potential criteria, that is, increase in product quality, increase in recycling rate, increase in process capacity, decrease in labour costs, decrease in energy costs and decrease in disposal costs; and (b) rank 25 key technologies that have been selected as being the most likely to benefit the efficient sorting of WEEE. The results indicate that the first stage in the development of any total system to achieve maximum economic recovery of materials from WEEE has to be the selection and application of appropriate fractionation process technologies to concentrate valuable components such as critical metals into the smallest possible fractions to achieve their recovery while minimising the disposal costs of low-value products. The stakeholder-based study has determined the priority for viable technical process developments for efficient WEEE fractionation and highlighted the economic and technical improvements that have to be made in the treatment of WEEE.

Value recovery from spent lithium-ion batteries: A review on technologies, environmental impacts, economics, and supply chain

<abstract> <p>The demand for lithium-ion batteries (LIBs) has surged in recent years, owing to their excellent electrochemical performance and increasing adoption in electric vehicles and renewable energy storage. As a result, the expectation is that the primary supply of LIB materials (e.g., lithium, cobalt, and nickel) will be insufficient to satisfy the demand in the next five years, creating a significant supply risk. Value recovery from spent LIBs could effectively increase the critical materials supply, which will become increasingly important as the number of spent LIBs grows. This paper reviews recent studies on developing novel technologies for value recovery from spent LIBs. The existing literature focused on hydrometallurgical-, pyrometallurgical-, and direct recycling, and their advantages and disadvantages are evaluated in this paper. Techno-economic analysis and life cycle assessment have quantified the economic and environmental benefits of LIB reuse over recycling, highlighting the research gap in LIB reuse technologies. The study also revealed challenges associated with changing battery chemistry toward less valuable metals in LIB manufacturing (e.g., replacing cobalt with nickel). More specifically, direct recycling may be impractical due to rapid technology change, and the economic and environmental incentives for recycling spent LIBs will decrease. As LIB collection constitutes a major cost, optimizing the reverse logistics supply chain is essential for maximizing the economic and environmental benefits of LIB recovery. Policies that promote LIB recovery are reviewed with a focus on Europe and the United States. Policy gaps are identified and a plan for sustainable LIB life cycle management is proposed.</p> </abstract>

Grouting Performance Evaluation of the Double Injection Method for Settlement Restoration of Concrete Rail Tracks

For the construction of concrete tracks, strict settling control standards are applied. However, settlement inevitably occurs owing to the construction conditions, climate, and geographical conditions. When settlement occurs beyond the limited value, recovery work is performed by using a restoration method. During restoration processes, the concrete track must maintain its support stiffness and not develop non-uniform stress to ensure proper functioning of interface systems between the track and roadbed and geometric settlement recovery. To satisfy these conditions, the track must be tightly filled to prevent voids from occurring at the bottom. This paper proposes a double-injection-type method for cement grouting to secure filling, considering the injection material, pressure, and interval. In this study, the filling performance was evaluated through field tests using visual inspection and the impact echo technique, which are non-destructive investigation methods.

Multi-tree cut-to-length harvesting of short-rotation poplar plantations

Small tree size represents the main challenge when designing a cost-effective harvesting system for European short-rotation plantations. This challenge is further complicated by the need to obtain 4-m logs for high-end products, which rules out the possibility of deploying whole-tree chipping. Both challenges can be met through mass or multi-tree handling (MTH), which must begin at the time of felling and continue uninterrupted along the whole supply chain. The objective was to: (1) gauge the productivity and the cost of CTL harvesting applied to these plantations; (2) assess log yield and capacity to match dimensional specifications; (3) determine if MTH applied to CTL technology offers a real benefit compared with conventional single-tree handling. The authors conducted a time study using a block design with a two-machine cut-to-length harvesting system (i.e. harvester and forwarder) in single- and multi-tree handling operations on the clear cutting of a hybrid poplar plantation in Poland, as well as we manually measured the produced volumes of the study. Higher productivity (+ 8%) was achieved under the multi-stem handling mode. The MTH system proved capable of containing harvesting costs below € 15 per green ton, while fulfilling set timber quality requirements in terms of value recovery and log quality specifications. A new, software-based, MTH system is recommended to be used in short-rotation poplar plantation for logs and biomass harvesting. When the coppicing season is over, the system can be deployed for the conventional thinning operations.