The Study of Carbon Materials in the Pyrometallurgy Method to Recovery of Silver Metal from Computer Circuit Board Scraps

Document Type : Research Article


1 Department of Chemistry, Amirkabir University of Technology, Tehran, I.R. IRAN

2 Department of Chemistry, Semnan University, Semnan, I.R. IRAN


In this paper, the recycling of silver metal from computer circuit board scraps was investigated by the pyrometallurgy method. In this method, firstly, the computer circuit board scraps were mechanically crushed by a jaw crusher and then were pulverized according to the vibratory of the disc mill machineIn the next step, the sample was melted by charging material. The choice of charging materials for the production of low slag and the formation of the lead-gold-silver alloy was very important, and among the charge materials, carbon materials due to ash and the effect of various oxides of its elements on the efficiency of extraction and production of slag were investigated. In this study, various carbon materials such as gas coke, iron melting metallurgy coke, semi-coke, coal, and charcoal were studied.
As a result, the semi-coke was selected for higher fixed carbon (84.87%) and ash (8.97%) and also less aluminum oxide (11.87 %) in the ash, then the amount of its optimum value was 6 g. Also in this study, charcoal because of high ash (14.20 %) and tin oxide in its ash (3.54 %) has the lowest extraction efficiency (65%) and the highest amount of slag (45%). In the next stage, the lead-gold-silver alloy was separated from the slag phase on the basis of a large difference in the mass volume of the slag phase. Then the silver metal was separated from the gold by the parting process. Finally, the silver was extracted by the process of cementation. In this method, extraction efficiency was reported to be 94%.


Main Subjects

[1] Herat S., International Regulations and Treaties on Electronic Waste (e-waste), J. Environ. Eng., 4: 335-351 (2009).
[2] Yoshida A., Terazono A., Ballesterros F.C., Nguyen D.Q., E-Waste Recycling Processes in Indonesia, the Philippines, and Vietnam: A Case Study of Cathode Ray Tube Tvs and Monitors, Resour. Conserv. Recy., 106: 48-58 (2016).
[3] Chen M.J., Ogunseitan O.A. J.B., Wang J., Chen H., Evolution of Electronic Waste Toxicity: Trends in Innovation and Regulation, J. Environ. Eng., 47: 12409-12416 (2013).
[4] Egyn E.V., Meester S.D., Tran H.P., Dewulf, Resource Savings Urban Mining: The Case of Desktop and Laptop Computers in Belgium, J. Resour. Conserv. Recy., 107: 53-64 (2016).
[5] Yan Lu, Zhenming Xu., Precious Metals Recovery from Waste Printed Circuit Boards: A Review for Current Status and Perspective, Resour. Conserv. Recy., 113: 28-39 (2016).
[6] Nilanjana Das., Recovery of Precious Metals Through Bio-Sorption: A Review, Hydrometallurgy, 103: 180-189 (2010).
[7] Gurungt M., Adhikarit B.B., Kawakitat H., Ohtot K., Selective Recovery of Precious Metals From Acidic Leach Liquor of Circuit Boards of Spent Mobile Phones Using Chemistry Modified Persimmon, Ind. Eng. Chem. Res., 51:11901-11913 (2012).
[8] Birloaga I., Vegilo F., Overview on Hydrometallurgical Procedures for Silver Recovery from Various Wastes, J. Environ. Eng., 18: 275-310 (2018).
[9] Isildar A., Vossenberg J.V., Rene E.R., Hullebusch E.D., Two-Step Bioleaching of Copper and Gold From Discarded Printed Circuit Boards (PCB), Waste Manage., 57:149-157 (2015).
[10] Tunsu G.; Retegan T., Chapter6-Hyrometallurgical Processes for the Recovery of Metals from WEEE, WEEE Recy., 139-175 (2016).
[11] Tuncuk A., Stazi V., Akcil A., Yazici E.Y., Deveci H., Aqueous Metal Recovery Techniques From E-Scrap: Hydrometallurgy in Recycling, Miner. Eng., 25: 28-37 (2012).
[12] Akcil A., Erust C., Gahan C.S., Ozgun M.,  Precious Metal Recovery from Waste Printed Circuit Boards Using Cyanide and Non-Cyanide Lixiviants-A Review, Waste Manage., 45: 258-271 (2015).
[13] Reith F., Zammit C.M., Rogers S.L., Potential Utilization of Microorganism in Gold Processing, Miner. Process. Extr. Metall. Rev., 121: 251-260 (2012).
[14] Cui j., Zhang L., Metallurgical Recovery of Metals from Electronic Waste: A Review, J. Hazard. Mater., 158: 228-256 (2008).
[15] Flandinet L., Tedjar F., Ghetta V., Fouletier J., Metals recovering from Waste Printed Circuit Boards (WPCBs) Using Molten Salts, J. Hazard. Mater., 213: 485-490 (2012).
[16] Bidini G., Fantozzi F., Bartocci P., Recovery of Precious Metals from Scrap Printed Circuit Boards Through Pyrolysis, J. Anal. Appl. Pyrolysis., 84: 175-183 (2014).
[17] Wills B.A., Napier – Munn T., "An Introduction to the Practical Aspects of Ore Treatment and Mineral Recovery ", Miner. Process. Technol. Seventh Edition Elsevier, (2007).