Effect of Acid Leaching Pre-Treatment on Gold Extraction from Printed Circuit Boards of Spent Mobile Phones.

The effect of a preliminary acid leaching for the recovery of gold by thiourea from printed circuit boards (PCBs) of spent mobile phones, was investigated. Preliminary leaching is aimed to recover copper in the leachate that would compete with gold in the successive leaching of the residue with thiourea, thus preventing the formation of the gold-thiourea complex. Two hydrometallurgical routes were tested for the recovery of copper first, and gold after.

Leaching test procedure for assessing the compliance of the chemical and environmental requirements of hardened woody biomass fly ash cement mixtures.

The compliance of the chemical and environmental requirements for using woody biomass fly ash (WBFA) as a mineral admixture in cement-based materials was studied in terms of the use of the cement-biomass fly ash concrete where the fluids surrounding and interacting with it renew themselves over time. The study was preceded by a preliminary characterization of WBFA whose results showed that the European chemical requirements (EN 450-1, 2012) established for the reuse of coal fly ash in cement-based materials (there is no normative for WBFA) were met except for the chloride content. A blend with a quite high content of WBFA (30%) and Portland cement (70%) was prepared to test the leaching behaviour of the cement-biomass fly ash concrete.

Evaluation of the leachability of heavy metals from cement-based materials.

A new leaching test on comminuted (0.125-2.0mm gradation) cementitious matrices, designated as Modified-Pore Water (M-PW) test, was developed to evaluate the effect of varying leachate pH (4-12.

Reuse of cement-solidified municipal incinerator fly ash in cement mortars: physico-mechanical and leaching characteristics.

The reuse of cement-solidified Municipal Solid Waste Incinerator (MSWI) fly ash (solidified/stabilised (S/S) product) as an artificial aggregate in Portland cement mortars was investigated. The S/S product consisted of a mixture of 48 wt.% washed MSWI fly ash, 20 wt.