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
188 F Móricz, F. Mádai & I. F. Wälder 5. Conclusions The three stages shown above are members of a natural progression for weathering of iron sulphide containing tailings and waste rocks. The fresh material starts oxidizing with increasing rate, then with time the reaction rate becomes stable, and finally decreases. The complete process looks like a bell shaped curve as it is shown on Fig. 9, where a theoretical pyrite oxidation curve is present. The graph is illustrating waste rocks were there is no or little neutralising / buffering reactions, such as massive sulphide deposits and polymetallic veins like the Itos deposit. Fig. 9. Pyrite oxidation changes in function of a long term process (after Ritchie, 1994). 9. ábra. A piritoxidüció mértékének hosszú távú időbeli változása (Ritchie, 1994 után). This three-year-long investigation indicated the maturity of the tailings and waste materials. Table II gives an overview of the different oxidation rate stages of the samples. The three stages define also the rates of the emitted pollution and heavy metal mobility. In the first - type “A” - stage the pollution and heavy metal content will increase with time. The material in this stage need correct waste management and appropriate handling. If the material is in the middle stage, the oxidation and the heavy metal mobility are at the maximum, as the pH is the lowest in this stage. In this stage at least controlling and monitoring is required. The third, the strongly oxidized stage means that the tailing or waste rocks are already after the peak pollution. The material in this stage is stable enough not to be able to cause any environmental problem. The slowing down reactions ensures that the heavy metal mobility decreases as the pH increases. The normalizing pH controls mineral alteration, as iron oxi-hydroxides and oxides are produced. Finally a gossan type mineralization could be formed as a cover on the waste.
