Phase and chemical composition of historical Zn-Pb slag from the dump in Ruda Sloka (Silesian Province, southern Poland)

The locations and structures testifying the historic Zn-Pb ore exploitation and processing are found in numerous southern Poland regions, especially Silesian Province. The Zn-Pb slag dump in Ruda Slaska, which is over one hundred years old, is an example of such a location. Chemical composition tests have exhibited that the slag is characterized by a relatively rich mineral composition with Si and Fe's dominant content. Impurities in the form of heavy metals, i.a. Zn, Pb, Cd, As, and rare earth metals: La, Dy, and Y, have also been identified. The components of which the slags are comprised include near-equal amounts of silica glass and crystalline phases represented by oxides (hematite, spinel, magnetite, and hercynite) and by silicates (fayalite, forsterite, augite, anorthite, mullite, and quartz). The crystalline phases rarely form euhedral shapes and are mostly found in fine glass-surrounded crystallites. Based on the conducted mineralogical and chemical analyses, it has been established that the tested slags are a waste material resulting from the processing of locally found oxidized Zn-Pb ores - so-called calamine - rich in iron impurities.