Adaptation of Acidithiobacillus ferrooxidans, Acidithiobacillus thiooxidans and Leptospirillum ferrooxidans strains on sphalerite concentrate from mining waste

Abstract

One of the main characteristics of the microorganisms used in the leaching process is their capacity to adapt to aggressive environments, characterized by a notable presence of heavy metals. In this study the adaptation of the strains Acidithiobacillus ferrooxidans, Acidithiobacillus thiooxidans and Leptospirillum ferrooxidans was evaluated on a sphalerite concentrate from mining waste. In the adaptation tests, the energy source (ferrous sulphate) was gradually replaced by percentages of mineral pulp, ending with subcultures without the addition of an external energy source. The results show that the strains A. ferrooxidans and A. thiooxidans are more resistant to high concentrations of sphalerite, compared to the strain of L. ferrooxidans, since, in the case of this strain, it was necessary to repeat some tests (8% of pulp), since a deficient development was evident. This was associated with factors such as the decrease of the Fe+2 energy source, the increase of the pulp density, the accumulation of toxic metals and secondary products of the dissolution of minerals and the increase of the pH.

Bioleaching of Zinc from Blast Furnace Cast House Dust

“…The goals of this experiments were: (I) the determination of the ideal sulfur concentration to cover the microorganisms' necessities and, therefore, produce the highest amount of sulfuric acid, and (II) the leaching of the highest achievable zinc share while obtaining the lowest possible remaining sulfur in the already treated solid residue. Since the exposure of the microorganisms to a residue could possibly affect the microorganisms [22], batch experiments were conducted with (10, 30, 40 and 50 g/L) in 250 mL shaker flasks prior to the CSTR tests. The results of these experiments showed that no inhibition occurred.…”