Metallurgical Waste Landfills as Potential Anthropogenic Deposits

Metallurgical slags produced in the zinc–lead, copper, iron and steel metallurgical industries are characterized by a variety of technical parameters and varying chemical and mineral compositions, which depend on the type of raw material and the technological process selected and its workflow. These slags are characterized by a high content of valuable elements, including Cu, Pb, Zn, and Fe, which form complex multiphase conglomerates. In the chemical composition of Zn-Pb smelting slags, the contents of the dominant elements, i.e., Fe, Zn, and Pb, range from a few to several dozen %. These elements occur mainly in the form of polyphase oxides and silicates. The chemical composition of Cu smelting slag contains up to a few % Cu and up to several dozen % Fe, with these elements mainly forming silicates and sulphides. Iron and steel metallurgy slag contains up to several dozen % Fe, which occurs mainly in the form of silicates, oxides, and spinels. Due to their phase composition, metallurgical slags stored in landfills can have a negative impact on the environment. The phase composition of slags is one of the main factors determining their behavior in a weathering environment, i.e., their ability to release metals when exposed to atmospheric factors such as precipitation or temperature. On the other hand, such high concentrations of elements in metallurgical slags mean that they become anthropogenic deposits, and the phase composition of the slags determines how the deposited slags are processed. The aim of this article is to present the mineralogical and chemical characteristics of Zn, Pb, Cu and steel metallurgical slags deposited in landfills, along with an assessment of these materials as a source of secondary raw materials.