Author: Thomas A. SullivanPublisher:
ISBN:
Category : Aluminum
Languages : en
Pages : 24
Book Description
Recovery of Aluminum, Base, and Precious Metals from Electronic Scrap
Author: Thomas A. SullivanPublisher:
ISBN:
Category : Aluminum
Languages : en
Pages : 24
Book Description
Recovery of Precious Metals from Electronic Scrap
Author: Raymond O. DannenbergPublisher:
ISBN:
Category : Copper
Languages : en
Pages : 28
Book Description
Recovery of Aluminum, Base, and Precious Metals from Electronic Scrap
Author: Thomas A. SullivanRecovery of Copper and Associated Precious Metals from Electronic Scrap
Author: H. B. SalisburyPublisher:
ISBN:
Category : Copper
Languages : en
Pages : 628
Book Description
Hydrometallurgical Treatment of Electronic Scrap to Recover Gold and Silver
Author: Recovery of Copper and Associated Precious Metals from Electronic Scrap
Author: H. B. SalisburyPublisher:
ISBN:
Category : Copper
Languages : en
Pages : 16
Book Description
Recovery of Base and Precious Metals from Waste Printed Circuit Boards
Author: Joelson AlvesPublisher:
ISBN:
Category :
Languages : en
Pages : 0
Book Description
Waste printed circuit boards (WPCBs) encompass about 3% of nearly 50 Mt of electronic waste (e-waste) annual generation representing one of the fastest-growing categories of global waste. WPCBs consists of glass-reinforced epoxy resins and a number of metallic components, including base and precious metals (PM) with a concentration higher than those of primary resources, making them economically attractive for recycling. The most significant and critical issue for the processing of e-wastes and WPCBs is to deal successfully with the halogenated flame retardants (HFR) content and heavy metals (such as Pb, Hg, and Cd), which make e-waste a hazardous waste with significant environmental concerns. The main objective of this study was to develop, design, and demonstrate a mechanical/physical separation flowsheet for efficient, low-cost, and environmentally sustainable recovery of base and precious metals from WPCBS. WPCBs, which were dismantled, shredded to 6 cm top size, and processed using a thermolyzer process by CHZ Technology Inc. were used in this study. The thermolyzer process produced clean syngas and plastic-free solid char, while producing no environmental hazards. The solid char mainly contained metals, carbon, and fiber glass. The solid char was first fully characterized for the liberation and potential recovery of base and precious metals. The elemental content of the char-metal mixture results showed that the base metals in the sample were mainly Cu (19.5%) and Al (4.3%). Regarding the precious metals, the sample contained approximately 32 ppm of Au, 10 ppm of Ag, and 3 ppm of Pd. The analysis of size and density fractions showed that most (i.e., 60-80%) of the base metals, reported to the coarse fractions (+1.19mm). The concentration of Cu in the coarse fractions varied from approximately 20-30% and was found to be less than 20% in the finer fractions. Aluminum had higher concentrations, ranging from 4 to 6% in the fractions coarser than 0.149 mm, and its concentration decreased to less than 1% in the fraction finer than -0.149 mm. The majority (i.e., 69%) of the Au was present in the fine fractions (-1.19 mm), out of which approximately 34% by weight with Au concentration of about 50 ppm was reported in the finest size fraction (i.e., -0.149 mm). Ag and Pd were relatively equally distributed in all other fractions ranging from 5-12 ppm and 1-4 ppm, respectively. The sized density fractionation showed that the metals in the fraction coarser than 0.5 mm were interlocked, while the size fractions of 0.5 mm x 0.149 mm, and finer than 0.149 mm were relatively and well liberated. Therefore, only the former fraction was required to be comminuted to increase liberation, and the latter fractions were screened and directly subjected to appropriate physical separation. As a result, the feed to the comminution circuitry was reduced by 12%. Integrated with the removal of plastic components by the thermolyzer process, the reduction of the feed load to the comminution circuitry was 52%. The content of non-metals., base metals, and precious metals in their corresponding sized density fractionations revealed that base and precious metals can be potentially concentrated by gravity separation. Upon characterization, the differences in the malleability of metals present in WPCBs was utilized for the selective liberation of metals in PCBs in various size fractions. The WPCBs were mechanically processed through comminution by rod mill followed by screening to liberate metals in various size fractions. The milling retention time was optimized to maximize the degree of liberation and minimize overgrinding, reducing energy consumption and preventing excessive generation of fine particles. The optimum milling time was found to be 15 min, equivalent to 2 kg/h feed rate in the laboratory rod mill, for metal liberation, at which more than 80% degree of liberation of metal was obtained without overgrinding the materials. Upon optimization, materials coarser than 0.5 mm were comminuted using rod mills for metal liberation, followed by screening into coarse, medium, and fine (+0.5 mm, 0.5 mm x 0.149 mm, and -0.149 mm, correspondingly) fractions for downstream physical separation. To investigate the potential of physical separation techniques to concentrate Cu, Al, Au, Ag, and Pd, gravity and magnetic separations were studied. A wet jigging, shaking table, and multi-gravity separator (MGS) were utilized for the coarse, medium, and fine size fractions. The Cu and Al recovery using the jig was found to be 92% and 80% with a grade of 72% and 14%, respectively. The shaking table concentrated Cu with 69% and 87% grade and 60% and 87% recovery, Au with 416 ppm and 36 ppm grade and 86% and 91% recovery, Ag with 272 ppm and 107 ppm grade and 38% and 90% recovery, Pd with 6.8 ppm and 7 ppm grade and 19% and 82% recovery for both non-ground and ground samples, respectively. Al with grade more than 11% and recovery more than 70% was obtained in the shaking table middling and tailing. MGS recovered 98% and 99% of Cu with 9.6% and 16% grade, 99% and 97% of Al with 8% and 8% grade, 68% and 67% of Au with 143 ppm and 87 ppm grade, 90% of Ag with 26 ppm grade, and 94% and 89% of Pd with 7 ppm and 6 ppm grade for both non-ground and ground samples, respectively. Based on obtained results, a process flowsheet was proposed. The flowsheet can produce a concentrate of significantly high grade and recovery of target elements using the combination of low-cost and environmentally friendly physical separation processes. The results showed that Cu, Al, Au, Ag, and Pd with 45%, 10%, 134 ppm, 89 ppm, and 6 ppm grade and 93%, 61%, 70%, 72%, and 80% recovery, respectively, were successfully produced. The recovery and grade values can be further improved through the addition of cleaner and scavenger units as well as recirculating loads. The flowsheet provides a successful pathway for recycling WPCBs.
Recycled Metals in the United States
Author: Hydrometallurgical Treatment of Electronic Scrap Concentrates Containing Precious Metals
Author: Henry E. HilliardPublisher:
ISBN:
Category : Electronic materials
Languages : en
Pages : 24
Book Description
Metal Recovery from Electronic Waste: Biological Versus Chemical Leaching for Recovery of Copper and Gold
Author: Arda IşildarPublisher:
ISBN: 9780367087050
Category : Copper
Languages : en
Pages : 0
Book Description
Waste electrical and electronic equipment (WEEE) generation is a global problem. This PhD research investigates novel metal recovery technologies from WEEE.