Challenges and opportunities in the recovery of gold from electronic waste

Rapid global technological development has led to the rising production of electronic waste that presents both challenges and opportunities in its recycling. In this review, we highlight the value of metal resources in the printed circuit boards (PCBs) commonly found in end-of-life electronics, the differences between primary (ore) mining applications and secondary (‘urban’) mining, and the variety of metallurgical separations, in particular those that have the potential to selectively and sustainably recover gold from waste PCBs

Optimization of process parameters for the selective leaching of copper, nickel and isolation of gold from obsolete mobile phone PCBs

The sequential separation of base and precious metals from the end-of-life mobile phone printed circuit boards (PCBs) is a significant challenge for the development of recycling process that exhibit material circularity. In this contribution, a simple, eco-friendly, and efficient leaching process is developed for the dissolution of copper and nickel from obsolete mobile phone PCBs to facilitate the isolation of a gold-rich residue. Chemical pre-treatment of downsized PCBs produced a metallic portion for which the leaching parameters for copper and nickel were optimised, including the type of leaching reagent, temperature, time, pulp density and agitation speed. It was found that quantitative dissolution of base metals occurred using 3.0 M nitric acid at 30 °C with a 50 g/L pulp density, 2 h residence time, and 500 rpm stirring speed; under these conditions, no gold was dissolved. Design of Experiment analysis using Response Surface Methodology was also undertaken to validate the process. Finally, the kinetics of the leaching process were studied and shown to conform to the chemically controlled surface reaction model, with activation energies of 39.7 and 18.4 kJ/mol for copper and nickel. Importantly, the leaching process optimised in this work avoids the need for high temperatures and reduces energy consumption and effluent generation, leading to the cleaner processing of obsolete mobile phone PCBs for the separation of gold from the dominant base metals

EXPERIMENTAL WORK ON DIESEL ENGINE PERFORMANCE AND EMISSION CHARACTERISTICS USING NANO ADDITIVES IN DIESEL AND BIODIESEL

ABSTRACT Diesel engines are well adapted by mankind because of their low fuel consumption and better efficiency. In recent times researchers have focused more on alternate fuels, with the depleting trend of petro diesel. Biodiesel is the one of such alternate fuel whose calorific value nearer to diesel. Most of the researchers concluded that with the usage of biodiesels the emissions can be reduced maintaining the consistency in efficiency, compared to diesel. In the present era of Nano technology there is the scope to improve the efficiency of engines using Nano additives in blended fuels. In this work single cylinder 4 stroke DI diesel engine is selected. The performance of different blends of mahua oil methyl esters for which cerium oxide (CeO2) Nano additives of size 30-50 nm is added in different proportions in blended fuel. The experiment has been conducted with neat diesel fuel and diesel-biodiesel blends (addition of cerium oxide (CeO2) Nano additive) in a four stroke single cylinder direct injection (DI) diesel engine. Those results are compared with conventional diesel fuel, diesel-biodiesel blends showed good performance, lower carbon monoxide (CO), and hydro carbons(HC) but higher oxides of nitrogen (NOx) emission.

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Not AvailableThis study aims to document the long line resources and the variation in gear used for long line fishing off the Visakhapatnam coast. The study was conducted among a sample of 193 long line units and 19 commercial fishing voyages involved in long line fishing of Visakhapatnam and Kakinada fishing harbours. Field survey method was adopted for data collection. Based on species landed, the catch was grouped into five categories viz., yellow fin tuna (Thunnus albacares), skipjack tuna (Katsuwonus pelamis), sharks (Carcharhinus sp.), Marlin (Makaira indica) and sword fish (Xiphias gladius). Yellow fin tuna dominated the catch contributing to 46.5% of the total catch. Marlins dominated the catches among species other than tuna by sharing 43.7% of the total catch, followed by sharks (32.5 %). Skipjack tuna contributed about 14.3% and Sword fish about 9.52% of the total catch.The details about the species landed with their hooking rates and the gear used are described.Not Availabl

Design and Development of a Dual-Volume Ionization Chamber for an Accident Monitor to Detect Gamma Radiation During Emergency Conditions in a Nuclear Reactor

A Gamma Ionization Chamber was developed for the purpose of high gamma radiation detection during accident conditions in a Light Water reactor. The pre-eminence of the detector is that it was designed and developed to monitor gamma exposure rates in the wide range of 100 mR/hr to 107 R/hr. The detector has an overall diameter of 90 mm with a length of 400 mm. The response of the detector is accurate and the sensitivity is within ± 6% over gamma energies ranging from 660 KeV to 1.25 MeV. The detector operates with a DC voltage of 500V. The V0.9 voltage is about 250V for 107 R/hr. The estimated operation life of the detector is about 20 years.&nbsp

Deliberate Activities Of The board and its Significance

New departments have been added to our publications and conferences, and new approaches have been incorporated in our research since the inception of M&SOM. Will they benefit the field in any significant way? Some regard them as a hindrance, resulting in a disjointed society that is unable to communicate effectively because its members do not share a common language. Others rejoice in the increased diversity we've achieved and the new frontiers it has opened up for scientific study. We contend that neither side is completely incorrect, nor completely accurate. We, too, maintain that we must contribute to an ever-expanding range of areas by employing all available methods of investigation.. The challenge of fragmentation is one that we share with the people who raised it earlier. To break out of its rut  and  have  greater  influence,  the discipline has to raise meaningful questions and deliver fascinating answers. I avoid the trap of specificity (great solutions to narrowly defined topics), (ii) connect and actively interact with various audiences, and (iii) be brave to pioneer new fields of investigation. When it comes to many of today's most pressing problems, operations management is a critical component