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

Abstract

The most neglected part of the scrap computers are the keyboards, which are generally incinerated by the informal recycling sectors creating environmental pollution and leading to the wastage of precious metallic contents present in it. The present paper is focused on a novel chemical processing technique developed to recover silver (Ag) as a value-added product and low-density oil (L D Oil) from computer keyboards. Initially, scrap keyboards were manually dismantled to separate Mylar sheets, and the same were pyrolyzed at 300 ◦C for 2 h to recover L D Oil. The obtained pyrolyzed Mylar sheets were further crushed, milled, and homogenized to reduce particle size (− 100 mesh). The crushed sample was leached using 2 M HNO3 at 60 ◦C in a mixing time of 20 min and the 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 into the 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 applications orientation to the industry after piloting the process.