Cadmium mobility from slag phases to the environment: Cadmium concentrations and distribution in two types of slags from Pb-Zn smelting in Swiętochłowice (Upper Silesia, Poland)

Cadmium is a toxic element, generally highly mobile and easily transferred from Cd-bearing ore minerals to the environment as shown by numerous leaching experiments and studies of biota. However, the behaviour of Cd is less understood during smelting activities, when it is transferred from Cd-bearing ore to the metal as well as to the smelting by-product slag. Slag material, with Cd concentrations over 500 mg/kg, occurs at an abandoned slag pile after Pb-Zn metal smelting in Swiętochłowice (Upper Silesia). Such material, extremely enriched in Cd (15 mg/kg is a legislative guideline for industrial soils), offers a possibility to study the distribution of Cd within slag fragments composed of silicates and oxides, gaining insight into Cd mobility. Electron microprobe analyses of primary slag show that Cd partitioning between different phases is not controlled by site preference and Cd does not substitute for elements with similar radius, such as Zn in Zn-spinel or Ca in Pb-hardystonite. Cadmium is strongly incompatible and enriched in late melts that, in the case of the studied slag, crystallize PbACCEPTED MANUSCRIPT