Recycling the Gan Waste from LED Industry by Pressurized Leaching Method

In recent years, with the increasing research and development of the LED industry which contains GaN, it is expected that there will be a large amount of related wastes in the future. Especially the gallium has extremely high value of economic, therefore, it is necessary to establish the recycling system of the GaN waste. However, GaN is a direct-gap semiconductor and with high energy gap, high hardness, and high melting point make it difficult to recycle. Therefore, this study will analyze the physical characteristics of LED wastes containing GaN and carry out various leaching method to leach the valuable metals from the waste optimally. Different acids are used to find out the best reagent for leaching the gallium. Different experimental parameters are discussed such as the effect of the different acid agents , concentration, pressure, solid-liquid mass ratio, temperature, and time which influence the leaching efficiency of the gallium. In this study, various leaching methods which effect the leaching efficiency of the gallium are compared and the advantages and disadvantages are discussed. Finally, pressurized acid leaching method is preferred to leach the GaN waste, and hydrochloric acid is used as the leaching solution because of its better leaching efficiency of gallium. Eventually, the leaching efficiency of the gallium can reach to 98%.

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Recycling the GaN Waste from LED Industry by Pressurized Leaching Method

Metals ◽

10.3390/met8100861 ◽

2018 ◽

Vol 8 (10) ◽

pp. 861 ◽

Cited By ~ 6

Author(s):

Wei-Sheng Chen ◽

Li-Lin Hsu ◽

Li-Pang Wang

Keyword(s):

Energy Gap ◽

Light Emitting Diode ◽

Economic Value ◽

Acid Leaching ◽

High Hardness ◽

High Energy ◽

Light Emitting ◽

Valuable Metals ◽

Leaching Solution ◽

Leaching Efficiency

In recent years, with the increasing research and development of the light-emitting diode (LED) industry, which contains gallium nitride (GaN), it is expected that there will be a large amount of related wastes in the future. Gallium has an extremely high economic value, therefore, it is necessary to establish a recycling system for the GaN waste. However, GaN is a direct-gap semiconductor and with its high energy gap, high hardness, and high melting point, these make it difficult to recycle. Therefore, this study will analyze the physical characteristics of LED wastes containing GaN and carry out various leaching methods to leach the valuable metals from the waste optimally. Different acids are used to find out the best reagent for gallium leaching. Different experimental parameters are discussed, such as the effect of the different acid agents, concentration, pressure, liquid-solid mass ratio, temperature and time, which influence the leaching efficiency of gallium. Finally, acid leaching under high pressure is preferred to leach the GaN waste, and hydrochloric acid is used as the leaching solution because of its better leaching efficiency of gallium. Optimally, the leaching efficiency of gallium can reach 98%.

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Study on Recovering of Value Metals from Acid Leaching Solution of Roasted Electroplating Sludge

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.524-527.1951 ◽

2012 ◽

Vol 524-527 ◽

pp. 1951-1955 ◽

Cited By ~ 1

Author(s):

Xiao E Dang ◽

Xin Zhe Lan ◽

Yuan Dong

Keyword(s):

Recovery Rate ◽

Acid Leaching ◽

Recovery Process ◽

Zinc Powder ◽

Environmental Benefits ◽

Pollution Problem ◽

Valuable Metals ◽

Electroplating Sludge ◽

Environmental Pollution Problem ◽

Leaching Solution

Chelating electroplating sludge contains high grade of toxic metals or heavy metals, so this sludge should be treated and recovered of valuable metals from it. This paper mainly studied on the recovery process of Copper, Nickel and Zinc process from sulfuric acid leaching solution of roasted chelating electroplated sludge. It provided an effective technique for recovery of valuable metals from acid leaching solution. The efficiency of the process had been measured with the metal recovery rate. Experimental results showed that recovery rate of Copper and Nickel can respectively achieve at 99.30% and 97.00% from acid leaching solution after removal iron with zinc powder used reducing agent. The process has simple operation and high recovery rate. It can solve the environmental pollution problem of electroplating sludge and valuable metals can be recovered from which. It could bring better economic and environmental benefits to the enterprise.

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Recovery of Platinum from Spent Petroleum Catalysts: Optimization Using Response Surface Methodology

Metals ◽

10.3390/met9030354 ◽

2019 ◽

Vol 9 (3) ◽

pp. 354 ◽

Cited By ~ 4

Author(s):

Yunji Ding ◽

Huandong Zheng ◽

Jiayi Li ◽

Shengen Zhang ◽

Bo Liu ◽

...

Keyword(s):

Response Surface Methodology ◽

Response Surface ◽

Avrami Equation ◽

Operating Variables ◽

Reduction Of Iron ◽

Leaching Solution ◽

Spent Catalysts ◽

Hcl Concentration ◽

Solid Liquid ◽

Leaching Efficiency

The global yield of platinum (Pt) recovery from spent catalysts is about 30%. Pt recovery from spent catalysts is one of the most significant methods to reduce its supply risk and meet future demand. The current hydro-leaching processes always involve extremely high acidity (c(H+) > 6.0 mol/L), causing serious environmental issues and consuming large amounts of reagents. This paper studied the recovery of Pt from spent petroleum catalysts in a mild leaching solution (c(H+) = 1.0−2.0 mol/L). The HCl and NaCl were used as leaching agents, while H2O2 was used for oxidation of Pt. The leaching factors, including solid/liquid ratio (S/L), acidity, leaching temperature, and H2O2 usage, were studied. The leaching efficiency of Pt was 95.7% under the conditions of S/L of 1:5 g/mL, HCl of 1.0 mol/L, NaCl of 5.0 mol/L, 10% H2O2/spent catalysts of 0.6 mL/g, and temperature of 90 °C for 2 h. The leaching kinetic of platinum fits best to the Avrami equation. The apparent activation energy for leaching platinum was 114.9 kJ/mol. Furthermore, the effects of the operating variables were assessed and optimized by employing a response surface methodology based on Box-Behnken Design. The result shows that HCl concentration had the greatest impact on the leaching efficiency as compared to the H2O2 concentration and S/L ratio. Pt leaching efficiency was increased to 98.1% at the optimized conditions of HCl of 1.45 mol/L, NaCl of 4.55 mol/L, 10% H2O2/spent catalysts of 0.66 mL/g, and S/L of 1:4.85. The purity of Pt is over 90% by the reduction of iron powder.

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An efficient and environmentally friendly route for PbS crystal recovery from lead ash generated in tin removal section (LATR) via high-speed leaching and recrystallization method

Journal of Mining and Metallurgy Section B Metallurgy ◽

10.2298/jmmb200308035f ◽

2021 ◽

pp. 35-35

Author(s):

Y. Feng ◽

X.-Q. Peng ◽

H.-H. Shi ◽

W. Zhang ◽

Q.-T. Zuo

Keyword(s):

High Speed ◽

Nitrate Solution ◽

Lead Nitrate ◽

Acid Leaching ◽

Molar Ratio ◽

Nitric Acid Leaching ◽

Leaching Solution ◽

The Common ◽

Tin Removal ◽

Leaching Efficiency

This paper mainly investigated on synthesis of a high purity PbS crystal directly from lead ash which was collected from Tin ash removal process (LATR). The LATR was firstly disposed by nitric acid leaching system to generate the lead nitrate solution. The PbS crystal would be prepared by mixing the lead nitrate solution with the sodium sulfide at the room temperature (25 ?C). The effects of molar ratio of HNO3 to Pb in the LATR on Pb leaching efficiency was investigated, demonstrating that the Pb leaching efficiency could attain to 82.9 % at molar ratio of 3. The leaching ratio of As, Cu, Fe, and Al generally increased with increasing molar ratio of HNO3 to Pb in the LATR, while 99.99 wt% of Sn was still left in the residue. In the process of generating PbS crystal from the leaching solution, the yield of PbS crystal was increased with increasing molar ratio of Na2S to Pb in the filtrate. The yield of PbS crystal could up to 93.1% at a molar ratio of 1.5. Overall, this method proved to be an efficient and environmental friendly route for synthesis of high quality PbS crystal directly from the common lead containing waste from the lead ore or secondary smelting factory.

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A p–n fusion strategy to design bipolar organic materials for high-energy-density symmetric batteries

Journal of Materials Chemistry A ◽

10.1039/d1ta02059e ◽

2021 ◽

Author(s):

Jihyeon Kim ◽

Heechan Kim ◽

Sechan Lee ◽

Giyun Kwon ◽

Taewon Kang ◽

...

Keyword(s):

Energy Density ◽

Organic Material ◽

Energy Gap ◽

High Energy ◽

High Energy Density ◽

Lumo Energy ◽

Fusion Strategy ◽

Redox Active ◽

Bipolar Type ◽

Homo Lumo

A new bipolar-type redox-active organic material with a wide HOMO–LUMO energy gap is designed though the ‘p–n fusion’ strategy.

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Mathematical modeling and experimental study on solid–liquid suspension separation in ultrasonic standing wave field

Journal of Low Frequency Noise Vibration and Active Control ◽

10.1177/14613484211022984 ◽

2021 ◽

pp. 146134842110229

Author(s):

Yajing Wang ◽

Liqun Wu ◽

Yaxing Wang ◽

Yafei Fan

Keyword(s):

Standing Wave ◽

Sound Pressure ◽

Acoustic Radiation ◽

Sound Field ◽

Radiation Force ◽

High Energy ◽

Factors Affecting ◽

Liquid Suspension ◽

Ultrasonic Standing Wave ◽

Solid Liquid

A new method of removing waste chips is proposed by focusing on the key factors affecting the processing quality and efficiency of high energy beams. Firstly, a mathematical model has been established to provide the theoretical basis for the separation of solid–liquid suspension under ultrasonic standing wave. Secondly, the distribution of sound field with and without droplet has been simulated. Thirdly, the deformation and movement of droplets are simulated and tested. It is found that the sound pressure around the droplet is greater than the sound pressure in the droplet, which can promote the separation of droplets and provide theoretical support for the ultrasonic suspension separation of droplet; under the interaction of acoustic radiation force, surface tension, adhesion, and static pressure, the droplet is deformed so that the gas fluid around the droplet is concentrated in the center to achieve droplet separation, and the droplet just as a flat ball with a central sag is stably suspended in the acoustic wave node.

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Recovery of Zinc and Silver from Zinc Acid-Leaching Residues with Reduction of Their Environmental Impact Using a Novel Water Leaching-Flotation Process

Minerals ◽

10.3390/min11060586 ◽

2021 ◽

Vol 11 (6) ◽

pp. 586

Author(s):

Yunpeng Du ◽

Xiong Tong ◽

Xian Xie ◽

Wenjie Zhang ◽

Hanxu Yang ◽

...

Keyword(s):

Hazardous Waste ◽

Acid Leaching ◽

Copper Recovery ◽

Water Leaching ◽

Flotation Process ◽

Metal Levels ◽

Valuable Metals ◽

Leaching Experiments ◽

Zinc Hydrometallurgy ◽

Poor Stability

Zinc-leaching residue (ZLR) is a strongly acidic hazardous waste; it has poor stability, high heavy metal levels, and releases toxic elements into the environment. ZLR has potential as a valuable resource, because it contains elevated levels of zinc and silver. In this paper, the recovery of zinc (Zn) and silver (Ag) from ZLR wastes from zinc hydrometallurgy workshops using water leaching followed by flotation was studied. During water leaching experiments, the zinc and copper recovery rates were 38% and 61%, respectively. Thereafter, various flotation testing parameters were optimized and included grinding time, reagent dosages, pulp density, flotation time, and type of adjuster. Experimental results demonstrated this flotation method successfully recycled Ag and Zn. A froth product containing more than 9256.41 g/t Ag and 12.26% Zn was produced from the ZLR with approximately 80.32% Ag and 42.88% Zn recoveries. The toxicity characteristic leaching procedure (TCLP) results indicated the water-leaching flotation process not only recycled valuable metals such as zinc and silver in zinc-containing hazardous wastes but lowered the hazardous waste levels to those of general wastes and recycled wastes in an efficient, economical, and environmentally friendly way.

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Prospects for fast reactors

Proceedings of the Royal Society of Edinburgh Section B Biological Sciences ◽

10.1017/s0269727000009532 ◽

1987 ◽

Vol 92 (1-2) ◽

pp. 57-71

Author(s):

C. W. Blumfield

Keyword(s):

Fast Reactor ◽

High Energy ◽

High Energy Density ◽

Fast Reactors ◽

Advantages And Disadvantages ◽

Reactor Technology ◽

European Collaboration ◽

Fast Reactor Fuel ◽

Fuel Reprocessing ◽

Planned Activities

SynopsisThe background to recent major advances in the construction and operation of fast reactors is outlined with particular reference to the Dounreay Prototype Fast Reactor. The advantages and disadvantages of sodium as a coolant of the high energy density assembly are discussed and an account given of the consequences of a leak and the precautions taken against this eventuality. Attention is drawn to the safety aspects of the system. The economics of the plans for fuel reprocessing are explained and an account given of the progress in the fabrication of fast reactor fuel pins. Finally the environmental impact of present and planned activities on the Dounreay site is presented in the context of participation in the European Collaboration on Fast Reactor Technology and attention drawn to the importance of the planning inquiry in progress at Dounreay.

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Leaching kinetics of copper and valuable metal extraction from copper-cadmium residues of zinc hydrometallurgy by oxidation acid leaching

International Journal of Chemical Reactor Engineering ◽

10.1515/ijcre-2021-0077 ◽

2021 ◽

Vol 0 (0) ◽

Author(s):

Jihao Guo ◽

Hongao Xu ◽

Bo Li ◽

Yonggang Wei ◽

Hua Wang

Keyword(s):

Hydrogen Peroxide ◽

Acid Concentration ◽

Acid Leaching ◽

Metal Extraction ◽

Agitation Rate ◽

Leaching Kinetics ◽

Solid Ratio ◽

Zinc Hydrometallurgy ◽

Kinetics Of ◽

Leaching Efficiency

Abstract Multiple purification of zinc sulfate solution is an important process for zinc hydrometallurgy, and large quantities of copper-cadmium residues are generated as byproducts in this process. Copper-cadmium residues contain a large number of valuable metals that must be recovered. A comprehensive extraction process has been proposed using sulfuric acid as the leaching reagent and hydrogen peroxide as the oxidizing reagent. The effects of acid concentration, leaching temperature, leaching time, liquid-to-solid ratio, hydrogen peroxide dosage and stirring speed on the leaching efficiency were investigated. The optimum conditions were determined as an acid concentration of 150 g/L, liquid-to-solid ratio of 4:1, hydrogen peroxide amount of 20 mL, time of 60 min, temperature of 30 °C, particle size of −d75 μm, and agitation rate of 300 r/min. It was concluded that the leaching efficiency of copper and cadmium reached 97%, but because of the existence of zinc sulfide in the residues, a lower leaching efficiency of zinc was obtained. Furthermore, the leaching kinetics of copper was also studied based on the shrinking core model. The activation energy for copper leaching was 5.06 kJ/mol, and the leaching process was controlled by the diffusion through the product layer.

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