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Non-toxic, high selectivity process for the extraction of precious metals from waste printed circuit boards

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Frontiers of Environmental Science & Engineering 2023年第10期17卷 65-74页

作者： Giulia Merli Alessandro Becci Alessia Amato Francesca Beolchini Department of Life and Environmental Sciences Polytechnic University of MarcheAncona 60131Italy

The work presented here focused on the extraction of gold (Au), silver (Ag) and palladium (Pd) from electronic waste using a solution of ammonium thiosulfate. Thiosulfate was used as a valid alternative to cyanide for precious metal extractions, due to its non-toxicity and high selectivity. The interactions between sodium thiosulfate, total ammonia/ammonium, precious metal concentrations and the particle size of the waste printed circuit boards (WPCBs) were studied by the response surface methodology (RSM) and the principal component analysis (PCA) to maximize precious metal mobilization. Au extraction reached a high efficiency with a granulometry of less than 0.25 mm, but the consumption of reagents was high. On the other hand, Ag extraction depended neither on thiosulfate/ammonia concentration nor granulometry of WPCBs and it showed efficiency of 90% also with the biggest particle size (0.50 precious metal leaching is a complex process (mainly for Au, which requires more severe conditions in order to achieve high extraction efficiencies) correlated with reagent concentrations, precious metal concentrations and WPCB particle sizes. These results have great potentiality, suggesting the possibility of a more selective recovery of precious metals based on the different granulometry of the WPCBs. Furthermore, the high extraction efficiencies obtained for all the metals bode well in the perspective of large-scale applications.

关键词： Thiosulfate Printed circuit boards precious metals Leaching Hydrometallurgy

precious metals Identification in Computer Motherboards

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材料科学与工程（中英文A版） 2023年第2期13卷 43-47页

作者： Hebah Abdel-Wahab Tamara Gund Science Technology Engineering&Mathematics Devision Middlesex County CollegeEdison 08818New JerseyUnited States Department of Chemistry and Environmental Science New Jersey Institute of TechnologyNewark 07102New JerseyUnited States

Elements can be classified into metals,nonmetals,or metalloids based on their chemical and physical properties.precious metals are rare and expensive.There are ten known precious metals,three of which are of interest to investors,silver,gold,and platinum.The goal is to find physical methods to identify the presence of precious metals,silver,and gold in the metal components of the computer motherboard,and to confirm its presence by chemical methods for its use and its selling to the jewelry industry after it is physically separated from the computer motherboards.Physical and chemical tests were identified.Physical tests include inscription test,magnet test and specific gravity test for both silver and gold metal pieces and chemical tests include bleach test,nitric acid test,test karat solution kit,and jewelry test kits.

关键词： precious metals gold silver identification tests computer motherboards

Potential recovery of precious metals from waste laptops in Jordan

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Rare metals 2015年第7期34卷 517-521页

作者： Mohammad A.T.Alsheyab Program Manager of Civil and Environmental Engineering Qatar Foundation

To achieve a sustainable development in the electronic and electrical equipment(EEE) industry, it is necessary to protect the available natural resources.In addition, to satisfy the increasing demand on EEE, it is necessary to provide alternative sources of raw materials.In this paper, laptops were imported to Jordan in 2011 as an example to show the potential recovery of metals and precious metals from high grade waste electronic and electrical equipment by conducting a mass flow rate analysis using the STAN program.The results show that considerable amounts of gold, silver, cobalt, palladium,and copper could be recovered.This will reduce the amounts needed from primary natural resources and offset the CO2 emissions produced from mining the primary raw material resources.

关键词： precious metals Laptops Waste of electronic and el

Progress in Microwave Technology Applied to the Recovery of precious metals from the Secondary Resources

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贵金属 2012年第A1期33卷 33-39页

作者： WANG Shixing PENG Jinhui CHEN Anran ZHANG Zebiao Faculty of Metallurgical and Energy Engineering Kunming University of Science and TechnologyKunming 650093China Ytmnan Institute of Supervision and Inspection for Product Quality Kunming 650000China

The recovery of precious metals from the secondary resources by microwave technology has emerged in recent years. Microwave technology as a new method for the recovery of precious metals has shown significant advantages against the conventional recovery procedures. This paper presents a review of the advances in microwave technology applied to the recovery of precious metals from the secondary resources. Many different applications are considered, including microwave-assisted leaching, microwave augmented ashing and microwave pyrolysis. In general, microwave enhanced recovery of precious metals from secondary resources.

关键词： microwave recovery precious metals secondary sources

New Technology for High Efficient Recovery of precious metals Six-component Alloy Wastes

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贵金属 2012年第A1期33卷 1-4页

作者： DONG Wei WU Xian ZHANG Ji CAI Xingshun Westrern Materails Co. Ltd. Northwest Institute for Non-ferrous Metal Research Xi'an 710016China

Aimed at high content of valuable metals, complicated composition, difficult to separation of precious metals six component alloy wastes, the present paper proposed a new technology of high efficient separation and purification. Using fragmentation technology realizes fast dissolution of palladium, silver, copper and zinc in the wastes, and high efficient and complete separation of them from gold and platinum; using evaporation thermal decomposition technology of mixed solution produced by nitric acid dissolving palladium, silver, copper and zinc, complete and high efficient separation of silver from palladium was realized; by control of solution acidity, using hydrazine reduction method, high efficient and complete separation of gold from platinum was realized. Using this new technology, the recovery rates of palladium and silver are above 99%, and gold and platinum above 98%, the grade of pure metals are above 99.95%.

关键词： precious metals six-component alloy wastes recovery

General approach for atomically dispersed precious metal catalysts toward hydrogen reaction

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Carbon Energy 2023年第7期5卷 100-111页

作者： Ruisong Li Daoxiong Wu Peng Rao Peilin Deng Jing Li Junming Luo Wei Huang Qi Chen Zhenye Kang Yijun Shen Xinlong Tian State Key Laboratory of Marine Resource Utilization in South China Sea Hainan Provincial Key Lab of Fine ChemistrySchool of Chemical Engineering and TechnologyHainan UniversityHaikouChina

As a carbon-free energy carrier,hydrogen has become the pivot for future clean energy,while efficient hydrogen production and combustion still require precious metal-based catalysts.Single-atom catalysts(SACs)with high atomic utilization open up a desirable perspective for the scale applications of precious metals,but the general and facile preparation of various precious metal-based SACs remains challenging.Herein,a general movable printing method has been developed to synthesize various precious metal-based SACs,such as Pd,Pt,Rh,Ir,and Ru,and the features of highly dispersed single atoms with nitrogen coordination have been identified by comprehensive characterizations.More importantly,the synthesized Pt-and Ru-based SACs exhibit much higher activities than their corresponding nanoparticle counterparts for hydrogen oxidation reaction and hydrogen evolution reaction(HER).In addition,the Pd-based SAC delivers an excellent activity for photocatalytic hydrogen evolution.Especially for the superior mass activity of Ru-based SACs toward HER,density functional theory calculations confirmed that the adsorption of the hydrogen atom has a significant effect on the spin state and electronic structure of the catalysts.

关键词： hydrogen evolution reaction hydrogen oxidation reaction photocatalytic hydrogen evolution reaction precious metals single-atom catalysts

Can news-based economic sentiment predict bubbles in precious metal markets?

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Financial Innovation 2022年第1期8卷 925-953页

作者： Aktham Maghyereh Hussein Abdoh Department of Accounting and Finance United Arab Emirates UniversityP.O.Box 15551Al AinUAE Department of Accounting and Finance The Citadel:The Military College of South CarolinaCharlestonSCUSA

This study examines the role of market sentiment in predicting the price bubbles of four strategic metal commodities(gold,silver,palladium,and platinum)from January 1985 to August 2020.It is the first to investigate this topic using sentiment indices,including news-based economic and consumer-based sentiments developed using different methods.We observed the role of sentiment as a reliable indicator of future bubbles for some metal commodities and found that bubbles were regularly concomi-tant with bearish sentiments for gold and platinum.Moreover,gold and palladium were the only commodities that experienced a bubble during the COVID-19 pandemic.Overall,our findings suggest inclusion of sentiment to the model that predicts the price bubbles of precious metals.

关键词： Asset price bubbles Market sentiment precious metals

Selective extraction and conversion of lignin in actual biomass to monophenols: A review

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Journal of Energy Chemistry 2016年第6期25卷 947-956页

作者： Zhicheng Jiang Changwei Hu Key Laboratory of Green Chemistry and Technology Ministry of Education College of Chemistry Sichuan University

Our over dependency on the fossil resource for industrial chemicals and fuels faces great challenges. Recently, the production of monophenols from lignin in lignocellulosic biomass is regarded as a promising process for sustainable biofuels. This article discusses the conversion of lignin in actual biomass directly to monophenols. The two step way including extraction of lignin from biomass and further degradation of the lignin oligomers to monophenols is especially discussed. The obtained monophenols can also be converted to chemicals with low-oxygen content via hydrodeoxygenation process. For extraction of lignin, co-solvent system is the most adopted for hydrolysis or solvolysis of lignin assisted by acid or alkaline catalysts. The structure of the obtained oligomers derived from lignin is discussed in detail. For lignin depolymerization, hydrogenolysis is an efficient method with the use of gaseous hydrogen or alcohols as hydrogen source. At the meantime, depolymerization mechanism and the route for repolymerization of the reaction intermediates are presented here. In hydrodeoxygenation process, metal catalysts, especially noble metal catalysts are required. The precise effects of the reaction solvents and catalysts on extraction and degradation of lignin need to be further investigated, and this will benefit to design more efficient strategies for lignin utilization. ? 2016 Science Press

关键词： Biomass Catalysts Extraction Hydrolysis Industrial chemicals Oligomers precious metals Reaction intermediates Reviews Solvents

Deselenization and detellurization of precious-metal ore concentrates by swelling oxidizing roasting and successive alkaline leaching

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International Journal of Minerals,Metallurgy and Materials 2017年第2期24卷 147-155页

作者： Fu-yuan Zhang Ya-jie Zheng Guo-min Peng School of Metallurgy and Environment Central South University Changsha 410083 China Henan Zhongyuan Gold Smelter Co. Ltd. Sanmenxia 472000 China Key Laboratory of Comprehensive Utilization of Gold Resource Sanmenxia 472000 China

A new technique of swelling oxidizing roasting and alkaline leaching was proposed for deselenization and detellurization of pre- cious-metal ore concentrates. Alkali-metal and alkaline-earth-metal chlorides and carbonates were preliminarily selected as swelling agents. The roasting removal rate and alkaline leaching rate of selenium and tellurium were investigated, and NaCl was selected as an appropriate swelling agent. Furthermore, the effects of various factors on the selenium gasification rate and leaching rate of selenium and tellurium were investigated. The results show that the selenium gasification rate reaches 88.41% after swelling oxidizing roasting for 2 h at 510~C using an NaC1 dosage coefficient of 100 and a sulfuric acid dosage coefficient of 1.3; the amorphous elemental tellurium is completely transformed into TeO2. The roasted product is subjected to alkaline leaching using a 100 g/L NaOH solution, which results in a selenium leaching rate of 10.51%, a total selenium removal rate of 98.92%, and a tellurium leaching rate of 97.64%. In the alkaline leaching residue, the contents of selenium, tellurium, gold, platinum, and palladium are 0.7825%, 5.492%, 8.333%, 0.2587%, and 1.113%, respectively; the precious metals are enriched approximately sixfold.

关键词： ore treatment precious metals roasting leaching selenium removal tellurium removal