The leaching behaviour of lead metallurgical slag in high-molecular-weight (HMW) organic solutions
The leaching behaviour of lead metallurgical slag in high-molecular-weight (HMW) organic solutions (in Speciation and toxicity, K. Hudson-Edwards (prefacer) and M. E. Hodson (prefacer))
Mineralogical Magazine (October 2005) 69 (5): 737-747
The reactivity of primary Pb metallurgical slags in high-molecular-weight (HMW) organic solutions has been studied in order to determine the processes of release and attenuation of metal and metalloid contaminants (Pb, Zn, Cu, As) in "soil-like" environments. Slag was submitted to a 112-day batch leaching experiment in Suwannee River fulvic acid solution and peat water (approximately 50 mg DOC l (super -1) ). The leaching was coupled with investigation of the secondary phases (SEM/EDS, Raman microspectrometry) and thermodynamic speciation-solubility modelling using MINTEQA2. Metals and As are released in large amounts during the early stage of the experiment, followed by a decrease in the concentrations in the leachate as a result of adsorption on secondary (hydrous) ferric oxides (HFO/FO), predicted by MINTEQA2 calculations and confirmed on the leached slag surface by SEM and Raman spectrometry. Compared to other contaminants, Zn exhibits more pronounced mobility and is adsorbed on HFO/FO only at pH>7. Such a scavenging process may be predominant during the long-term interaction of slag with an HMW organic solution of real soil. As a result, the soil cover and subsequent re-vegetation of slag dumps may be considered as a possible scenario for slag management.