| Abstract |
In Poland, the mineral sector generates 110-130 million tons of wastes annually (in the last 20 years), and metal ore mining alone was responsible for 31.2 million tons of wastes in 2017. The slags deposited at the Polkowice were investigated. This waste may be a potential source of many valuable metals (Zn, Pb, Cu, Sb, Sn, Se). The tailings dump in Polkowice contains approximately 80,000 tons of slag. The material contains primary phases formed by pyrometallurgical processes and secondary phases, which are the result of transformation of primary components. The primary phases are represented by sulfides: sphalerite [ZnS], wurtzite [(Zn,Fe)S]; pyrite [FeS2]; sulfates: beaverite-(Zn) [Pb(Fe23+Zn)(SO4)(2)(OH)(6)]; palmierite [(K,Na)(2)Pb(SO4)(2)]; oxides and hydroxides: goethite [Fe3+O(OH)]; wuestite [FeO]; hematite [Fe2O3]; magnetite [Fe2+Fe23+O4]; chromian spinet [Fe2+Cr23+O4]; silicates: petedunnite [Ca(Zn,Mn2+,Mg,Fe2+)Si2O6]; quartz [SiO2]; and microchne [KAlSi3O8]. Additionally, SEM-BSE observations revealed that oxidized native metals (Cu, Pb, As) and metal alloys and semi-metals appear. The slag consists mainly of SiO2 (13.70-20.60 wt%), Fe2O3 (24.90-39.62 wt%) and subordinately of CaO (2.71-6.94 wt%) and MgO (1.34-4.68 wt%). High contents are formed by Zn (9.42-17.38 wt%), Pb (5.13-13.74 wt%) and Cu (1.29-2.88 wt%). The slag contains trace elements Mo (487.4-980.1 ppm), Ni (245.3-530.7 ppm), Sn (2380.0-4441.5 ppm), Sb (2462.8-4446.0 ppm), Se (168.0-293.0 ppm). High concentrations are formed by toxic elements, such as e.g. As (13 100-22 600 ppm) and Cd (190.5-893.1 ppm). It is estimated that the tailings dump has accumulated about 80,000 t of slag, which may contain about 10,000 t of Zn, about 6,700 t of Pb, and 1,500 t of Cu. |