Leaching and Adsorption of Gold from Waste Printed Circuit Boards Using Iodine-Iodide Solution and Activated Carbon
Iodine-iodide leaching and activated carbon adsorption processes for recovery of gold (Au) from waste printed circuit boards (WPCBs) were discussed in this paper. A pressure oxidative acid leaching (POAC) was carried out in an autoclave using diluted sulfuric acid (1M H 2 SO 4 ) solution in order to remove high concentrations of some base metals especially copper (Cu), aluminum (Al), iron (Fe) and zinc (Zn) due to their negative effect on gold dissolution from WPCBs. The factors affecting the performance and efficiency of the iodine-iodide leaching process; such as iodine/iodide concentration, pulp density, leaching time and leaching temperature were optimized in order to maximize the gold dissolution efficiency from the WPCBs in the iodine-iodide solution. Results indicated that the vast majority (> 99%) of gold was dissolved in the solution from the WPCBs under the optimized leaching conditions. Adsorption tests were conducted on leach liquor solutions resulting from the iodine-iodide leaching using activated carbon. Nearly 98% of gold was adsorbed from the liquor solution onto the carbon under the condition optimized in this study. The results obtained revealed that gold can be successfully recovered from this secondary resources, where the percent recovery amounts to nearly 97% for gold.
Hydrometallurgical recovery of metals from waste printed circuit boards (WPCBs): Current status and perspectives – A review
Abstract Printed circuit boards (PCBs) represent one of the most complicated and valuable components in electric and electronic equipment (EEE). Waste PCBs (WPCBs) contain more than 40 kinds of metals with a wide and variable range of concentrations, such as environmentally harmful metals (e.g. Pb, Cr, As, Cd and Hg) and others of economic value (e.g. Cu, Sn, Au, Ag and Pd). Recovery of metals from WPCBs is of great importance for both environmental protection and resource re-utilization. In contrast to metal recovery from natural resources, these secondary resources have to be essentially stripped completely of its harmful metallic content before the remaining plastic substrate can be disposed, charred or incinerated. Hydrometallurgy has been successfully used for metals recovery from primary and secondary resources around the world, owing to its easily controlled process and high recovery rates at relatively low costs, and a number of researches using various hydrometallurgical methods for metals recovery from WPCBs has been published each year since 2002. This study provides an up-to-date review of the hydrometallurgical recovery of metals from WPCBs and gives perspectives of this particular area, which is expected to provide an insight for the selection of suitable hydrometallurgical leaching and purification methods and to point out the novel and potential technologies that would be the future focuses of this area.
Fundamentals and applications of ion exchange
Ion Exchange Towards the Twenty First Century.- The Use of Some Coordinating Copolymers in Hydrometallurgy.- The CCS-Ion Exchange Contactor.- Outlook and Desires of Ion Exchange Resin Technology Development in the Nuclear Field.- Purification of Effluents of Acid Copper and Nickel Plating Galvanic Processes with Conventional Cation Exchange Resins. Copper and Nickel Recovery.- Anion Resin Kinetics at High Flow Rates.- Ion Exchange Desulphation of Feedwater to MSF Evaporator. Full Scale Experience.- Calculation of Economic Indexes for Desalination Plants with and Without Desulphation Pretreatment System.- Kinetic Studies on Gel and Macroporous Anion Exchangers Using the Uranyl Sulfate/Sulfate Exchange.- Salt Conservation, Selectivity Reversal and Breakthrough Detection in Ion Exchange for Nitrate Removal.- Equilibrium and Diffusion Rate Effects of Univalent and Divalent Ions in a Bifunctional Resin.- Analysis of Ion Exchange Phenomena Occurring in Silicate Glasses Immersed in a Molten Salt Bath.- The Rim-Nut Process for Recovery of N/P Fertilizer From Sewage. Start-Up of Bari's Plant.- Ion Exchange for the Recycling of Wastewater Constituents.- Cation Exchange Softening Coupled with Electrodialysis for High Recovery Desalination.- Methods of Reducing Consumption of Sulphuric Acid in Regeneration of Strong Cation Exchangers in Water Desalination.- Design Methods for Ion Exchange Equipment.- Future Criteria for the Design and Manufacturing of Water Treatment Plants.- Water Softening for Food Processing.- Ion Exchange in the Food Industry.- Ion Exchange for the Recovery of Concentrated Ammonium Sulphate from the Process Condensate of an Ammonia-Urea Factory.- The Mechanism of Ion Exchange on Microcrystals of Inorganic Oxide-Hydroxides.- A Useful Method to Summarize Data in Ion Exchange - Influence of Temperature and Ionic Size.- Reversibility and Performances in Productive Ion-Exchange Chromatography.- Mossbauer and Electron Microprobe Studies of Precipitation Phenomena in Nafion Ion Exchange Membranes.- Ion Exchange Kinetics in Zeolite A.- Kinetics of Bulk and Interfacial Ionic Motion: The Microscopic Basis and Limits for the Nernst-Planck-Poisson System.- Nernst-Planck or No?.- Application of the Stefan-Maxwell Equations to Multicomponent Ion Exchange.- Concentration Polarization and Membrane Resistance Evaluation by Current Transient and Nernst-Planck Equations.