Heap leaching of Pb and Zn contaminated soil using ozone/UV treatment of EDTA extractants [An article from: Chemosphere]

This digital document is a journal article from Chemosphere, published by Elsevier in 2006. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.

Description:
The feasibility of a novel EDTA-based soil heap leaching method with treatment and reuse of extractants in a closed process loop was evaluated on a laboratory scale. Ozone and UV irradiation were used for oxidative decomposition of EDTA-metal complexes in extractants from Pb (1243mgkg^-^1) and Zn (1190mgkg^-^1) contaminated soil. Released metals were absorbed in a commercial metal absorbent Slovakite. Six-consecutive additions of 2.5mmolkg^-^1 EDTA (total 15mmolkg^-^1 EDTA) removed 49.6+/-0.6% and 19.7+/-1.7% of initial total Pb and Zn from soil (4.6kg) packed in 22cm high columns. The efficiency of extraction was similar to small-scale simulations of heap leaching (150g of soil), where EDTA used in the same manner removed 49.7+/-1.0% and 13.7+/-0.4% of Pb and Zn. The new heap leaching method produced discharge extractant with fairly low final concentrations of Pb, Zn and EDTA (1.98+/-2.17mgl^-^1, 4.55+/-2.36mgl^-^1, and 0.05+/-0.04mM, respectively), which could presumably be reduced even further with continuation of treatment. The results of our study indicate that for soils contaminated primarily with Pb, treating the EDTA extractants with ozone/UV and reuse of extractants enables efficient soil heap leaching with very little or no wastewater generation, easy control over emissions, and lowers the requirements for process water.