2. ENVIRONMENTAL ChEMISTRy & TEChNOLOGy 2.1. Lectures

Chem. Listy, 102, s265–s1311 (2008) Environmental Chemistry & Technology
the mineral and the cultural medium and after 14 days by
direct and indirect influence of bacteria At. ferrooxidans. This
fact demonstrates the comparison of the Fe dissolution curve
shape of At. ferrooxidans and abiotic control. It confirms the
bioleaching of pyrite (FeS 2 ).
Fig. 2. Dissolution of the Sb by bacteria Acidithiobacillus ferrooxidans
from the sample of gold-bearing antimony sulfide
minerals. . c – concentration of Sb, t – time of bioleaching,
– Acidithiobacillus ferrooxidans, – abiotic control
Fig. 3. Influence of bacteria Desulfovibrio desulfuricans for the
Fe dissolution under the alkaline leaching of gold-bearing antimony
sulfide minerals. c – concentration of Fe, t – time of bioleaching,
– Desulfovibrio desulfuricans, – abiotic control
Fig. 2. shows the trend of the Sb dissolving. Initially,
during 7 days the concentration of Sb increases in the At. ferrooxidans
presence and abiotic control, probably due to
interaction between the mineral and the cultural medium. After
7 days the abiotic control allocated the circa constant Sb
concentration in liquid phase until the end. After 35 days was
recorded the depression as follows was observed the decreasing
of the Sb concentration until the end of experiments in
the At. ferrooxidans presence. This fact can be interpreted on
the bases the creation of the insoluble antimony oxosulphates
– (SbO) 2 SO 4 according the reaction (1) 11 :
s410
Sb 2 S 3 + 6O 2 + 2H 2 O → (SbO) 2 SO 4 + 2H 2 SO 4
Figure 3 presents the Fe concentration in liquid phase at
the using bacteria Dsv. desulfuricans that was from beginning
until the end almost zero. Although the little increase was
observed after 19 days. This situation can be resolve by the
Fe precipitation with bacterially produced hydrogen sulphide
under the influence of bacteria Dsv. desulfuricans After 40
days it’s the intense increase was recorded in the experiments
without bacteria. Just now concerning this fact we have not
the adequate understanding. At the end of the experiments the
Fe concentration at presence SRB and abiotic control were
again almost zero.
Figure 4 shows the Sb concentration in the liquid phase
at the using bacteria Dsv. desulfuricans From the confrontation
of the Sb concentration curve shape in the abiotic control
and in the presence bacteria you can see that the influence of
bacteria Dsv. desulfuricans was not significant. The contamination
of the abiotic control by bacteria Dsv. desulfuricans
was not evidence. After 20 days was observed the formation
of the shined cover on the reactor wall in the presence bacteria.
Its can be explain to the Sb concentration decreasing.
Fig. 4. Influence of bacteria Desulfovibrio desulfuricans for the
Sb dissolution under the alkaline leaching of gold-bearing antimony
sulfide minerals. c – concentration of Sb, t – time of bioleaching,
– Desulfovibrio desulfuricans, – abiotic control
After ending the solid phases were recovered by filtration
from solution. The solid phases were saved for the
consequently test of cyanidation and liquid phases for the
electrowinning.
Conclusions
Experimental studies confirmed:
• the bacteria At. ferrooxidans have the positive influence
on the dissolving of pyrite (FeS2 ) and stibnite (Sb2S3 )
to occur in the used sample of gold-bearing antimony
sulphide minerals,
• the increase, subsequent the depression and the decreasing
of the Sb concentration during the bioleaching
(1)