Comparison of the oxidation kinetics of different pyrites in the presence of Thiobacillus ferrooxidans or Leptospirillum ferrooxidans

Bioleaching studies were carried out to determine the effect of both the chemical reactivity of the pyrite as well as the affinity of a bacterial strain to the ferrous to ferrite iron ratio, on the overall bacterial oxidation rate of a pyrite. Pure culture of Thiobacillus ferrooxidants and an enrichment culture of Leptospirillum bacteria on a framboidal pyrite from Germany and a euhedral pyrite from Prieska, South Africa were used. The results are discussed in terms of the relative affinities of T. ferrooxidants and the Leptospirillum bacteria for the ferrous/ferric-ion ratio, and susceptibility of the two types of pyrite to ferric leaching.