Scrap computer keyboards a sustainable resource for silver (Ag) and low density oil (L D Oil)

Abstract

Most neglected part of the scrap computers are the keyboards, which are generally incinerated by the informal recycling sectors creating environmental pollution and leads to the wastage of precious metallic contents present in it. Present paper is focused on a novel chemical processing technique developed to recover silver (Ag) as value added product and low density oil (L D Oil) from the computer keyboards. Initially, scrap keyboards were manually dismantled to separate Mylar sheets and the same were pyrolysed at 300 °C for 2 h to recover L D Oil. The obtained pyrolysed Mylar sheets was further crushed, milled and homogenized to reduce particle size (−100 mesh). The crushed sample was leached using 2 M HNO3 at 60 °C in mixing time of 20 min and pulp density of 100 g/L to achieve maximum dissolution of Ag. The leaching kinetics for Ag dissolution well fitted with chemical reaction control dense constant size cylindrical particles, 1-(1-X)1/2 = kct. The obtained leach liquor was put to cementation process using metallic copper (Cu). Almost 99% of Ag gets cemented as Ag powder in 15 min at a constant solution temperature of 60 °C and pH 1.1. The developed bench scale process has application orientation to the industry after piloting the process.