Fehér Béla (szerk.): Az ásványok vonzásában, Tanulmányok a 60 éves Szakáll Sándor tiszteletére (Miskolc, 2014)
Móricz Ferenc - Mádai Ferenc - Walder Ingar F.: Szulfidos bányászati meddőkben lezajló piritoxidáció időbeni változása
Temporal changes of pyrite oxidation in sulphidic mine wastes 185 samples have already been strongly corroded. In addition to the primary minerals - such as quartz, pyrite, galena and cassiterite -, secondary sulphates (various types from the jarosite subgroup and gypsum), different iron oxi-hydroxides and oxides were found. Intensive pyrite corrosion was detected both in tailings (Itos jig 1 and 2) and waste rock samples (Itos Granza 1 and 2) where the pyrite oxidation was usually complemented by formation of secondary iron sulphates. In Fig. 5, a corroded pyrite (Py) crystal with cassiterite grains is shown from the sample Itos Granza 2. Strongly corroded pyrite (Py) particles with secondary iron sulphates are in Fig. 6 from sample Itos Granza 1. The image of Fig. 7 shows secondary gypsum formation on galena and pyrite crystals in samples Itos jig 1 (Móricz et al., 2009). 4. Discussion Comparing the stabilized pFl values, thus the pyrite oxidation rates for the consecutive test periods, the maturity of the samples could be assessed. The samples can be split into three different stages: fresh / weakly oxidized, premature / partly oxidized and mature / strongly oxidized. Other important indicators are the corrosion textures of pyrite and the appearing different secondary mineral groups. The following stages are determined: In the weakly oxidized stage (marked type “A”) the pyrite oxidation rate is increasing in the consecutive years. Samples Bol 2 (Fig. 2) and Itos jig 2 (Fig. 4) are good representations of this type of behaviour. In the beginning oxi-hydroxide minerals appear as alteration products after the sulphides. Then the pFI goes below 2-2.5, so the oxi-hydroxide Fig. 5. Corroded pyrite (Py) with cassiterite (Cst) in Itos Granza 2. Width of the picture: 0.3 mm. 5. ábra. Oxidálódott piritszemcse (Py) kasz- sziterittel (Cst) az Itos Granza 2 mintában. Képszélesség: 0,3 mm.
