Treatment and recovery of contaminated railway ballast

Experimental tests of metal extraction from stones sampled from articially contaminated railway ballasts are presented and discussed. Metal extraction was performed by washing with aqueous solutions of disodium ethylenediaminetetraacetate (EDTA), at selected concentrations. The eectiveness of the remediation process was evaluated using leaching tests. The results indicate that the washing technology represents a successful and aordable solution for the implementation of an on-site treatment aimed at a reuse process. Adopting a 0.05 M EDTA solution, extraction yields in the range between 40% and 70% were achieved, depending on contact time and pH of the washing solution.