title: Recycling WEEE: Extraction and concentration of silver from waste crystalline silicon photovoltaic modules.
abstract: Photovoltaic modules (or panels) are important power generators with limited lifespans. The modules contain known pollutants and valuable materials such as silicon, silver, copper, aluminum and glass. Thus, recycling such waste is of great importance. To date, there have been few published studies on recycling silver from silicon photovoltaic panels, even though silicon technology represents the majority of the photovoltaic market. In this study, the extraction of silver from waste modules is justified and evaluated. It is shown that the silver content in crystalline silicon photovoltaic modules reaches 600g/t. Moreover, two methods to concentrate silver from waste modules were studied, and the use of pyrolysis was evaluated. In the first method, the modules were milled, sieved and leached in 64% nitric acid solution with 99% sodium chloride; the silver concentration yield was 94%. In the second method, photovoltaic modules were milled, sieved, subjected to pyrolysis at 500°C and leached in 64% nitric acid solution with 99% sodium chloride; the silver concentration yield was 92%. The first method is preferred as it consumes less energy and presents a higher yield of silver. This study shows that the use of pyrolysis does not assist in the extraction of silver, as the yield was similar for both methods with and without pyrolysis.
authors.affiliation: Programa de Pós-Graduação em Engenharia de Minas, Metalúrgica e de Materiais (PPGE3M), Universidade Federal do Rio Grande do Sul (UFRGS), Av. Bento Gonçalves, 9500, 91509-900 Porto Alegre, RS, Brazil. Electronic address: pablo.dias@ufrgs.br.
authors.forename: Pablo
authors.initials: P
authors.lastname: Dias
authors.affiliation: Programa de Pós-Graduação em Engenharia de Minas, Metalúrgica e de Materiais (PPGE3M), Universidade Federal do Rio Grande do Sul (UFRGS), Av. Bento Gonçalves, 9500, 91509-900 Porto Alegre, RS, Brazil.
authors.forename: Selene
authors.initials: S
authors.lastname: Javimczik
authors.affiliation: Programa de Pós-Graduação em Engenharia de Minas, Metalúrgica e de Materiais (PPGE3M), Universidade Federal do Rio Grande do Sul (UFRGS), Av. Bento Gonçalves, 9500, 91509-900 Porto Alegre, RS, Brazil.
authors.forename: Mariana
authors.initials: M
authors.lastname: Benevit
authors.affiliation: Programa de Pós-Graduação em Engenharia de Minas, Metalúrgica e de Materiais (PPGE3M), Universidade Federal do Rio Grande do Sul (UFRGS), Av. Bento Gonçalves, 9500, 91509-900 Porto Alegre, RS, Brazil. Electronic address: hugo.veit@ufrgs.br.
authors.forename: Hugo
authors.initials: H
authors.lastname: Veit
authors.affiliation: Programa de Pós-Graduação em Engenharia de Minas, Metalúrgica e de Materiais (PPGE3M), Universidade Federal do Rio Grande do Sul (UFRGS), Av. Bento Gonçalves, 9500, 91509-900 Porto Alegre, RS, Brazil.
authors.forename: Andréa Moura
authors.initials: AM
authors.lastname: Bernardes
mesh_terms: D011211:Electric Power Supplies; D059029:Electronic Waste; D017942:Nitric Acid / Q000737:chemistry; D059027:Recycling / Q000379:methods*; D012825:Silicon; D012834:Silver / Q000302:isolation & purification*; D012965:Sodium Chloride / Q000737:chemistry
chemical_list: D012834:Silver; D017942:Nitric Acid; D012965:Sodium Chloride; D012825:Silicon
keywords: Crystalline silicon; E-waste; Recycling; Silver recovery; Solar panel