scholarly journals Hydrometallurgical process for extraction of metals from electronic waste-part I: material characterization and process option selection

10.30544/382 ◽  
2009 ◽  
Vol 15 (4) ◽  
pp. 231-243 ◽  
Author(s):  
Željko Kamberović ◽  
Marija Korać ◽  
Dragana Ivšić ◽  
Vesna Nikolić ◽  
Milisav Ranitović
Keyword(s):  
Particle Size ◽  
Printed Circuit Boards ◽  
Precious Metals ◽  
Reduction Process ◽  
Absorption Spectrometry ◽  
Magnetic Fraction ◽  
Hydrometallurgical Process ◽  
Potassium Persulphate ◽  
Research Activities ◽  
Waste Pcbs

Used electronic equipment became one of the fastest growing waste streams in the world. In the past two decades recycling of printed circuit boards (PCBs) has been based on pyrometallurgy, highly polluting recycling technology which causes a variety of environmental problems. The most of the contemporary research activities on recovery of base and precious metals from waste PCBs are focused on hydrometallurgical techniques as more exact, predictable and easily controlled. In this paper mechanically pretrated PCBs are leached with nitric acid. Pouring density, percentage of magnetic fraction, particle size distribution, metal content and leachability are determined using optical microscopy, atomic absorption spectrometry (AAS), X-ray fluorescent spectrometry (XRF) and volumetric analysis. Three hydrometallurgical process options for recycling of copper and precious metals from waste PCBs are proposed and optimized: the use of selective leachants for recovery of high purity metals (fluoroboric acid, ammonia-ammonium salt solution), conventional leachants (sulphuric acid, chloride, cyanide) and eco-friendly leachants (formic acid, potassium persulphate). Results presented in this paper showed that size reduction process should include cutting instead of hammer shredding for obtaining suitable shape and granulation and that for further testing usage of particle size -3 +0.1mm is recommended. Also, Fe magnetic phase content could be reduced before hydro treatment.

A Novel Flowsheet for the Recycling of Valuable Constituents from Waste Printed Circuit Boards

2011 ◽  
pp. 296-306
Author(s):  
Jingfeng He ◽  
Yaqun He ◽  
Nianxin Zhou ◽  
Chenlong Duan ◽  
Shuai Wang ◽  
...  
Keyword(s):  
Printed Circuit Boards ◽  
Separation Efficiency ◽  
Precious Metals ◽  
Metal Recovery ◽  
Recovery Ratio ◽  
Circuit Boards ◽  
Printed Circuit ◽  
Waste Printed Circuit Boards ◽  
Waste Pcbs ◽  
Impact Crushing

Waste printed circuit boards (PCBs) contain a number of valuable constituents. It is of great significance to separate precious metals and non-metallic constituents from waste PCBs with appropriate methods for resource recycling and environment protection. A novel flowsheet for the recycling of waste PCBs using physical beneficiation methods was constructed. Waste PCBs were disassembled into substrates and slots firstly. The substrates were crushed to the size below 1mm through wet impact crushing and separated with a tapered column separation bed. The results indicated that products with integrated separation efficiency of 93.9% and metal recovery ratio of 93.7% were obtained by the primary separation with the water discharge of 5.5 m3/h, feed-rate of 250g/min and inclination angle of 35°. Waste PCBs slots components were crushed to the size of 0.5-5mm through impact crushing and separated with an active pulsing air classifier. The separation results showed that products with integration separation efficiency of 92.4% and metal recovery ratio of 96.2% were obtained with the airflow velocity of 2.90m/s and pulsing frequency of 2.33Hz. Precious metals could be obtained by further separation and purification of the metal components and the non-metal components could be used as refuse derived fuel. The flowsheet has great potential to be applied in the field of waste PCBs treatment and recycling.

Physical and Chemical Properties of the Waste Electronic Circuit Board

2013 ◽  
Vol 699 ◽  
pp. 900-903 ◽  
Author(s):  
Hong Fen Wang
Keyword(s):  
Printed Circuit Boards ◽  
Electronic Circuit ◽  
Chemical Properties ◽  
Precious Metals ◽  
Circuit Board ◽  
Physical And Chemical Properties ◽  
Gold Silver ◽  
Waste Pcbs ◽  
Physical And Chemical ◽  
And Chemical Properties

Printed circuit boards (PCBs) and copper-clad laminate (CCLs) are the foundation of the electronic industry, and the core components of all kinds of electronic products. With the accelerated pace of information equipment replacement, waste PCBs and CCLs increase every year, and generated a lot of e-waste. Sweden Ronnskar smelter made an analysis on elements of the PCBs used in the personal computer, the results showed that the PCBs generally contain precious metals gold, silver and non-ferrous metals such as copper, wherein the mass fraction of copper is up to 26.8%, the mass concentration of gold and silver respectively reached 80 g/t and 3300 g/t, which much higher than the average gold grade and having high recycling value. Waste PCBs also contain heavy metals such as lead, cadmium, chromium, which have a great deal of harm to the environment and human body. This paper focuses on the physical and chemical properties of the electronic circuit board such as calorific value and moisture, on the content measurement and analysis of gold, copper and other precious metals so that the physical and chemical properties of the ingredients in waste PCBs and CCLs are determined from a qualitative and quantitative point of view, which is very important for looking for recyclable value of the waste PCBs and CCLs and for determining the best method of recycling them. The test results showed that the waste PCBs and CCLs had very high recycling value.

scholarly journals Reduction Mechanism of Fine Hematite Ore Particles in Suspension

2021 ◽  
Author(s):  
Zhiyuan Chen ◽  
Christiaan Zeilstra ◽  
Jan van der Stel ◽  
Jilt Sietsma ◽  
Yongxiang Yang
Keyword(s):  
Particle Size ◽  
Temperature Drop ◽  
Reduction Rate ◽  
Reduction Process ◽  
Reciprocal Relationship ◽  
Drop Tube ◽  
Surface Nucleation ◽  
Order Of Magnitude ◽  
Relationship Of ◽  
Kinetics Of

AbstractIn order to understand the pre-reduction behaviour of fine hematite particles in the HIsarna process, change of morphology, phase and crystallography during the reduction were investigated in the high temperature drop tube furnace. Polycrystalline magnetite shell formed within 200 ms during the reduction. The grain size of the magnetite is in the order of magnitude of 10 µm. Lath magnetite was observed in the partly reduced samples. The grain boundary of magnetite was reduced to molten FeO firstly, and then the particle turned to be a droplet. The Johnson-Mehl-Avrami-Kolmogorov model is proposed to describe the kinetics of the reduction process. Both bulk and surface nucleation occurred during the reduction, which leads to the effect of size on the reduction rate in the nucleation and growth process. As a result, the reduction rate constant of hematite particles increases with the increasing particle size until 85 µm. It then decreases with a reciprocal relationship of the particle size above 85 µm.

scholarly journals Impact of Iron on the Fe–Co–Ni Ternary Nanocomposites Structural and Magnetic Features Obtained via Chemical Precipitation Followed by Reduction Process for Various Magnetically Coupled Devices Applications

Nanomaterials ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 341
Author(s):  
Tien Hiep Nguyen ◽  
Gopalu Karunakaran ◽  
Yu.V. Konyukhov ◽  
Nguyen Van Minh ◽  
D.Yu. Karpenkov ◽  
...  
Keyword(s):  
Particle Size ◽  
Magnetic Properties ◽  
Reduction Process ◽  
Chemical Precipitation ◽  
Precipitation Method ◽  
Magnetic Characteristics ◽  
Reduction Temperature ◽  
Fe Content ◽  
Magnetic Features ◽  
Co Precipitation

This paper presents the synthesis of Fe–Co–Ni nanocomposites by chemical precipitation, followed by a reduction process. It was found that the influence of the chemical composition and reduction temperature greatly alters the phase formation, its structures, particle size distribution, and magnetic properties of Fe–Co–Ni nanocomposites. The initial hydroxides of Fe–Co–Ni combinations were prepared by the co-precipitation method from nitrate precursors and precipitated using alkali. The reduction process was carried out by hydrogen in the temperature range of 300–500 °C under isothermal conditions. The nanocomposites had metallic and intermetallic phases with different lattice parameter values due to the increase in Fe content. In this paper, we showed that the values of the magnetic parameters of nanocomposites can be controlled in the ranges of MS = 7.6–192.5 Am2/kg, Mr = 0.4–39.7 Am2/kg, Mr/Ms = 0.02–0.32, and HcM = 4.72–60.68 kA/m by regulating the composition and reduction temperature of the Fe–Co–Ni composites. Due to the reduction process, drastic variations in the magnetic features result from the intermetallic and metallic face formation. The variation in magnetic characteristics is guided by the reduction degree, particle size growth, and crystallinity enhancement. Moreover, the reduction of the surface spins fraction of the nanocomposites under their growth induced an increase in the saturation magnetization. This is the first report where the influence of Fe content on the Fe–Co–Ni ternary system phase content and magnetic properties was evaluated. The Fe–Co–Ni ternary nanocomposites obtained by co-precipitation, followed by the hydrogen reduction led to the formation of better magnetic materials for various magnetically coupled device applications.

scholarly journals The Processing of Beach Sand from Sri Lanka for the Recovery of Titanium Using Magnetic Separation

2003 ◽  
Vol 12 (1) ◽  
pp. 13-22 ◽  
Author(s):  
W. A. P. J. Premaratne ◽  
N. A. Rowson
Keyword(s):  
Particle Size ◽  
Sri Lanka ◽  
Chemical Analysis ◽  
Titanium Content ◽  
Beach Sand ◽  
Magnetic Fraction ◽  
Chemical Characteristics ◽  
Magnetic Separator ◽  
Commercial Grade ◽  
Sand Deposit

An investigation has been carried out to study the mineralogical and chemical characteristics of beach sand deposits from Sri Lanka and application and optimisation of different magnetic separators (induced roll magnetic separator and disc magnetic separator) to improve the recovery of titanium from the deposit. Commercial grade titanium concentrates could be achieved employing both induced roll and disc magnetic separators. However, the titanium recovery increased greatly in the magnetic fraction with a titanium content of commercial grade (up to 63.9% TiO2) when paramagnetic titanium-bearing minerals were separated from beach sand using the disc magnetic separator. The results of the mineralogical and chemical analysis tests for the beach sand deposit indicated that 71% of beach sand was smaller than 355 μm in particle size and more than 99% of titanium content of the deposit was contained in this fraction.

Environmentally and Economically Sustainable Recovery of Precious Metals and Rare Earth Elements from Waste Printed Circuit Boards

2019 ◽  
pp. 299-312
Author(s):  
R. Khanna ◽  
M. Park ◽  
P.S. Mukherjee ◽  
S. K. Mishra ◽  
S. K. Biswal ◽  
...  
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Printed Circuit Boards ◽  
Precious Metals ◽  
Circuit Boards ◽  
Printed Circuit ◽  
Waste Printed Circuit Boards ◽  
Sustainable Recovery

Effect of Dispersant on the Particle Size Distribution of Cu Powders Prepared by Wet-Reduction Process

2007 ◽  
pp. 2118-2121
Author(s):  
Yong Yee Kim ◽  
Young Min Park ◽  
Hoy Yul Park ◽  
Hong Chae Park ◽  
Seog Young Yoon
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Reduction Process
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