Controls on Metal Leaching from Secondary Pb Smelter Air-Pollution-Control Residues

Abstract

Air-pollution-control (APC) residues are among the most toxic waste materials from secondary Pb metallurgy. Two distinct APC residues collected from bag-type filters of one Czech secondary Pb smelter were subjected to leaching experiments to determine the mineralogical and geochemical controls on leaching of metallic contaminants (Cd, Cu, Pb, Zn). A kinetic 720-h leaching test in deionized water at a liquid-to-solid (L/S) ratio of 10 L kg(-1) and a 48-h leaching test at various L/S ratios (0.5, 1, 5, 10, 50, 100, 500, and 1000 L kg(-1)) were performed and coupled with the mineralogical investigation of solid residues (TEM/EDS, XRD) and PHREEQC-2 speciation-solubility modeling. The rapid release of contaminants into the solution at all the L/S ratios showed the rapid dissolution of primary phases. The leaching at high L/S ratios, representing long-term predictions of leaching behavior, showed that primary alkaline sulfates and chlorides (Na3Pb2(S04)3Cl and KCl.2PbCl2) were dissolved and anglesite (PbSO4) was formed as their final and stable alteration product. Primary amorphous PbSO3 partly crystallized during leaching and oxidized to anglesite. These results are consistent with the mineralogical investigation of soils exposed for decades to Pb smelter emissions, where only anglesite was detected. The leaching experiments showed thatwashing residues at L/S >50 accompanied by spontaneous anglesite precipitation can be an alternative for improved technological treatment of these residues. Although this process would require further treatment of contaminated effluent, the newly precipitated anglesite is more favorable than the primary APC residue phases for an efficient metallurgical recovery of Pb.

Lead, Zn, and Cd in slags, stream sediments, and soils in an abandoned Zn smelting region, southwest of China, and Pb and S isotopes as source tracers

“…This could be attributed to the more mobile property of Cd and Pb than Zn in the environment (Podlesakova et al 2001), especially those affected by Zn smelting. Leaching experiments of air-pollution-control residues from smelting also indicated a more mobile feature of Cd than Pb and Zn (Ettler et al 2008). Even though enrichment factors of Pb and Zn varied, a very close correlation between Pb and Zn in samples can be computed (R 2 =0.805, p<0.01).…”

Differences in the bioaccessibility of metals/metalloids in soils from mining and smelting areas (Copperbelt, Zambia)

“…The dispersal of contaminants in the vicinity of mines and smelters is highly dependent on the local meteorological conditions, mainly on the prevailing wind direction (Ettler et al, 2005aKříbek et al, 2010). In addition, dust emitted by the smelters generally consists of fine-grained materials with extremely high specific surface area and high solubility, whereas particles generated by ore crushers in mining areas are generally larger in size (Ettler et al, 2005b(Ettler et al, , 2008Kříbek et al, 2010). Thus, the areas affected by smelterderived particles are generally larger than areas polluted by mining activities (Figs.…”

“…In contrast, the smelter dusts are generally composed of more soluble metal-bearing compounds (Ettler et al, 2005b(Ettler et al, , 2008. Recent investigations of the pH-dependent leaching behaviour of the copper smelter flue dust from one smelter in the Zambian Copperbelt indicated that primary chalcanthite (CuSO 4 ·5H 2 O) was readily dissolved, especially under acidic conditions and large amounts of Cu were released (Vítková et al, 2011).…”

The pH-dependent leaching of inorganic contaminants from secondary lead smelter fly ash

“…Qualitative analysis was performed with the X'Pert HighScore software 1.0 equipped with the ICDD PDF-2 database [14]. The results exclude the possible presence of amorphous admixtures, which were suggested by Ettler et al [15]. Quantitative determination of the phases (%) was performed by means of the Rietveld procedure using the Topas 3 software supplemented with the ICSD database [16].…”