New Process To Get The Lead Out of Soil

Cognis, a California-based subsidiary of Henkel Corporation (Germany) has developed a process to remove lead from soil, in such a way that the lead can be re-used, and the soil returned to the site. Contaminated soil is separated into its basic physical components of gravel, sand, silt and clay. The gravel is rinsed, tested for metal, then returned to the site if the metal level is low enough. The sand is pumped into a water-filled jig and shaken. The denser particles (lead) settle and are removed. A leachant (the secret bit of the process, patent pending) is added to the sand, to dissolve the remaining metal. This metal can be removed, and the leachant re-used. The sand is returned to the site. The silt and clay go through the same process.

Rewritten from "Chemecology", March/April 1994§