EXPERIMENTS
ON
COMBINED
ELECTRO
AND
BACTERIAL
LEACHING
(Sho
Communica ion)
K.P.
Teppe
and
R.
Na eke
Leh s uhl
ii
Mik obiologie,
Technische
Uni e si a
B aunschweig
B aunschweig,
FRG
Abs ac :
The
in luence
o
di ec
cu en
and
o
cu en
wi h
changing
he
poles
wo
imes
pe
sec
a
in ensi ies
o
0,2...15
mA
and
a
ensions
o
12...170
Von
leaching
o
py i e
dispe sed
in
qua zi e
in
pe cola-
o s
wi h
Thiobacillus
e ooxidans
was
s udied.
The
solu ion
o
i on
was
accele a ed
by
bac e ia
wi hou
cu en
and
by
cu en
wi hou
bac-
e ia,
bu
in
combina ion
he
accele a ion
did
no
exceed
he
sum
o
bo h
single
e ec s.
The
esul s
sugges
ha
he e
is
no
di ec
elec-
ophysiological
in luence
o
cu en
on
bac e ia
unde
condi ions
o
ou
expe imen s.
A
p esen
we
y
o
u ilize
indi ec
elec ochemical
e ec s
o
cu en
on
bac e ial
leaching
o
chalcopy i e.
In oduc ion
We
epo
abou
ou
i s
expe imen s
which
we e
s a ed
o
ge
answe s
on
some
ques ions
ela ed
o
a
combina ion
o
elec oleaching
wi h
bac e ial
leaching
o
o es.
Do
hese
p ocesses
in luence
each
o he
o
one
ano he
so
ha
he
e ec
is
g ea e
o
smalle
han
he
sum
o
he
e ec s
o
he
single
p ocesses?
Is
he e
any
di ec
elec ophysio-
logical
in luence
o
elec ic
ield
o
cu en
on
he
bac e ia,
o
is
he e
me ely
an
indi ec
e ec ,
e.g.
by
elec ochemical
p ocesses
in
he
medium
s imula ing
o
inhibi ing
he
g ow h?
May
bac e ial
me abo-
lism
accele a e
(o
inhibi
)
he
elec oleaching?
To
look
o
mo e
di ec
elec ophysiological
in luences
in
he
i s
se
o
expe imen s
we
ha e
chosen
py i e
as
he
mine al
o
be
leached
o
i
is‘known
ha
wi h
low
cu en
in ensi ies
he e
is
no
o ma ion
o
elemen al
sul u
om
py i e
which
would
se e
as
ene gy
sou ce
o
Th obaeilli.
[ne
o
ma ion
o
S°
would
ep esen
an
indi ec
elec ochemical
e ec .
212
K.
P.
Teppe
and
R.
N&é eke
Me hods
We
used
pe cola o s
as
shown
in
ig.
1.
The
medium,
230
ml
9
K
medium
o
Sil e man
and
Lundg en
/1/
wi hou
e ous
sul a e,
was
mo ed
h ough
he
pe cola o
by
ai
li .
The
calumn
was
illed
wi h
a
mix u e
o
acid
washed
qua zi e
(diame e
o
he
pieces
5...10
mm)
and 200
g
py i e
(diame e
0,5...2,0
mm).
A
1
cm?
pla inum
shee
was
inse ed
as
elec ode
in
he
uppe
laye
o
he
subs a e.
The
o he
elec ode
-
o
he
same
shape
-
was
inse ed
in
he
bo om
pa
benea h
a
pe o a ed
e lon
shee .
This pa
was
illed
wi h
medium
up
o
he
qua zi e.
Vol age
and
cu en
we e
deli e ed
by
an
equipmen
by
which
a
cons an
cu en
in ensi y
o
3, 8, 9,
12
o
15
mA
(p o ided
ha
he
aol ace
o
Up.
o
230.)
was.
su i-
cien )
o
a
cons an
ol age
up
o
230
V
(p o ided
ha
he
cu en
in-
ensi y
did
no
exceed
15
mA)
was
kep
cons an .
I on
concen a ion
was
de e mined
by
AAS,
bac e ia
concen a ion
by
di ec
mic oscopic
coun ing.
UPPER
ELECTRODE
<
QUARTZITE
a
+
PYRITE
}
oe
AIR
LIFT
PERFORATED
TEFLON
SHEET
9K
MEDIUM
w R
LOWER
ELECTRODE
H
SCREW
TUBE
CLAMP
Fig.
1:
Pe cola o
o
combina ion
o
bac e ial
and
elec o
leaching
o
py i e
wi h
Thiobacillus
e ooxidans
Combined
Elec o
and
Bac e ial
Leaching
Expe imen s
wi h
9
mA
213
In
mos
expe imen s
we
wo ked
wi h
di ec
cu en
o an
in ensi y
o
9
mA,
he
uppe
elec ode
as
anode,
s a ing
a
he
beginning
o
a
he
second
day
o
he
expe imen .
In
some
expe imen s
we
in e up ed
he
cu en
e e y
5
sec
o
5
sec,
and
in
some
o he
expe imen s
we
he
poles
wo
imes
pe
sec.
A
he
beginning
he
concen a ion
e ia
was
2.<.14,5
x
107
ma
and he
pH
was
3,0...3,2.
Con ols
up
wi hou
elec ic
cu en ,
wi hou
bac e ia
and
wi hou
bo h.
7?
days
un
a
26°C
in.
he
da k
we
ion
in
he
medium.
was
measu ed
and
added
o
ha
o
sul s
o
some
expe imen s
o
his
a e
shown
in
able
1.
:
o
The
amoun
o
Fe
changed
o
bac-
we e
se
A e
measu ed
pH
and
o al
i on
concen a-
p ecipi a ed
on
he
elec odes
he
o al
i on
in
he
medium.
The
en
g oup
wi h
cu en
in ensi y
o
9
mA
0 6
o al
i on
leached
om
py i e
and
pH
3
mA
e
e
a e
7
days
a
28°C
in
he
da k
cu en
Be
ne
ao
=
0
|
bac-
Fe|
pH
Fe|
pH
Fe|
pH
Fe|
pH
days
|
low
Ge
os
e ial)
mg,
mg
|
mg, mg,
o 0
0
112,78
112,60
1|2,90
112,778
113,15
oO
o
+
193
11,80
214
1,90
S50
(75
|
31911575
47614,821
212
11,90)
345
11,71
|
299)1,80
4.77
+|
CONLIN
«|
o
=
o
(112525
30
12,25
PANN20
7
2.-7.{con in.|
+
-
a
24
2,20|
5012.20
412,21
1.-7.{in e .|
+ -
0
38
|2,20
13512;29
4.7-7.
con in.
+
= +
235
1,60)
(00
11,95
9511,94]
269
11,80
45
12,00
63
;2,00
972,01
2.57.
COn in«l
+
=
+
4621165
|
160
11,90
35631,70
156
/1,90
344-14
5.75
Ao
7
an ennal
=
j
3241
11,75
7]
31214,80
|
354
11,721
169
11,96
|
1.-7.|
con in.|changing
+
i
S541,
70
4
{ i
Table
1:
Resul s
o
ou
se ies
o
expe imen s
on
py i e
leaching
wi h
Thiobacillus
e ooxidans
in
combina ion
wi h
elec ic
cu en
o
9
mA
in ensi y.
in
pe cola o s
214
K.
P.
Teppe
and
R.
Naé eke
The
esul s
show
clea ly
ha
wi hou
bac e ia
and
wi hou
cu en
he e
is
p ac ically
no
solu ion
o
i on,
wi h
cu en
alone
wi hou
bac e ia
he
leaching
is
only
slowly.
In
expe imen s
wi h
bac e ia
one
can
no
see
an
accele a ion
o
bac e ial
leaching
by
cu en .
I
mus
be
concluded
om
he
g ea
di e ences
be ween
he
alues
o
pa allel
esp.
simila
expe imen s,
ha
he e
mus
be
some
unknown
ac o s
which
in luence
he
bac e ial
leaching
p ocess.
Bu
looking
a
all
da a
i
can
be
concluded,
ha
i
is
unlikely
ha
he e
a e
di ec
posi i e
physio-
logical
e ec s
o
he
cu en
on
he
bac e ia,
a
leas
unde
he
con-
di ions
o
ou
expe imen s.
Expe imen s
wi h
0,2
and
1,0
mA
We
had
o
ake
in o
accoun
he
possibili y
ha
a
posi i e
in luence
o
he
cu en
on
he
bac e ia
was
abolished
by
nega i e
in luences
o
elec ochemical
e ec s.
So
we
s a ed
ano he
se ies
o
expe imen s
o
simila
ype
as
desc ibed
abo e
bu
wi h
cu en
in ensi ies
o
only
1,0
and
0,2
mA
and
o e
a
pe iod
o 30
days.
Du ing
his
ime
we
measu -
ed
e e y
day
pH,
o al
i on
concen a ion
and
concen a ion
o
bac e ia
in
he
medium.
Wi hou
bac e ia
he e
was
almos
no
change
a
all
in
pH
and
no
i on
was
dissol ed.
Wi h
bac e ia
he e
was
a
dec ease
o
pH
and
a
change
in
i on
concen a ion
wi h
wo
maxima
as
i
is
seen
in
ig.
2.
This
shape
o
he
cu e
was
he
same
in
se e al
expe imen s,
each
wi h
se e al
pa s
allels.
The
concen a ion
o
bac e ia
dec eased
in
all
expe imen s
in
he
i s
3
days
by
abou
10°,
possibly
by
adhesion
on o
he
su aces
o
he
solid;
hen
i
inc eased
o
4
alue
sligh
abo e
ha
a
he
be-
ginning
and
hen
emained
cons an .
I
is
seen
in
ig.
2
ep esen ing
ypical
esul s
o
an
expe imen
wi h
1,0
mA
ha
he e
is
p ac ically
no
di e ence
be ween
pe cola o s
wi h
cu en
and
wi hou .
This
was
he
case
as
well
wi h
cu en
in ensi y
o
0,2
mA
as
wi h
1,0
mA.
Conclusion
I
can
be
concluded
om
ou
esul s
ha
-
a
leas
in
ou
expe i-
men s
-
he e
is
no
di ec
physiological
in luence
o
cu en
on
he
bac e ia.
An
enhancemen
o
bac e ial
leaching
by
low
cu en
in ensi y
epo ed
by
o he
au ho s,
e.g.
/2/,
mus
depend
on
indi ec
elec oche-
mical
e ec s.
Bu
ob iously
hese
e ec s
we e
absen
in
ou
expe imen s
wi h
py i e.
Combined
Elec o
and
Bac e ial
Leaching
215
10+
‘
8a
a m
on
[
6
Oo
=
SN—WITH
CURRENT
Oo
Se
M9
SWITHOUT
CURRENT
Pp”
oO
os
~~
2-
0-4
10°+
ou
_-WITHOUT
CURRENT
xb
“WITH
CURRENT
,
19/4
<<
ye,
'
io
10°4
/!
oo
we
©
{|
<
x
mM
10-4
3,07
T
20+
_MWITHOUT
CURRENT
10
:
,
—-WITH
CURRENT
6
10
20 30
TIME
[DAYS]
Fig.
2:
Leaching
o
py i e
wi h
Thiobacillus e ooxidans
in
pe cola-
o s
a
26°C,
da k
meme
Wi h
di ec
cu en
a
cons an
in ensi y
o
1,0
mA
meme
wi hou
cu en

216
K.
P.
Teppe
and
R.
Na eke
Ou look
F om
epo s
o
Ralph
/3/
and
o
1114
and
Be am
/4/
i
mus
be
con-
cluded
ha
a
leas
in
he
case
o
chalcopy i e
one can
expec
posi i-
e
in luences
o
cu en
on
bac e ial
leaching.
By
anodic
oxida ion
ele-
men al
sul u
is
o med
on
he
su ace
o
chalcopy i e
c ys als
so
ha
an
easily
u ilizable
ene gy sou ce
o
Thiobacilli,
especially
o
T.
hiooxidans,
is
deli e ed.
This
migh
be
seen
as an
enhancemen
o
elec-
o
leaching
by
bac e ia
a he
han
an
enhancemen
o
bac e ial
leaching
by
cu en :
The
o ma ion
o
elemen al
sul u
dec eases
he
cu en
in-
ensi y
by
insula ion
he
chalcopy i e
pieces
by
a
laye
o
sul u
on
he
su aces
and
he e o e
inhibi :
he
leaching
p ocess.
Thiobacilli
oxidize
his
sul u
and
hus
keep
he
su aces
clean
and
mo eo e
o m
sul u ic
acid,
which
i sel
accele a es
he
leaching.
We
will
ollow
his
line
o
esea ch.
Re e ences
/1/-
M.P.Sil e man
and
D.G.Lundg en,
J.
Bac e iol.
by
B42
(1
959))
/2/
§.8.Gajda zie
and
F.N.Gence ,
Chimija
i
Indus i a,
So ija,
44.
18
(1972)
cn
73/7
-B.9:Ralph,
his
monog aph
/4/
H.1I11i
and
R.Be am,
his
monog aph