Buletinul Ştiinţific al Universităţii “Politehnica” din Timisoara, ROMÂNIA
Seria CHIMIE ŞI INGINERIA MEDIULUI
Chem. Bull. "POLITEHNICA" Univ. (Timişoara)
Volume 51(65), 1-2, 2006
Zinc Recover from Zinc Ash by Extraction with Clorhidric Acid
Solutions
Lavinia Lupa, Petru Negrea, Aurel Iovi, Mihaela Ciopec, Giannin Mosoarca
Faculty of Industrial Chemistry and Environmental Engineering, University “Politehnica” of Timişoara, ,
P-ta Victoriei no.2, 300006-Timisoara, email: lavinia.lupa@chim.upt.ro
Abstract: Zinc is the 27th most common element in the earth’s crust. More importantly, zinc is fully recyclable. Zinc can
be recycled indefinitely, without loss of its physical or chemical properties. In this paper was made studies regarding the
recover of zinc from zinc ash resulted during thermal zinc coating by extraction with clorhidric acid solutions in the view
of the zinc chloride solution obtaining which can be used at the obtaining of the flux solutions.
Keywords: zinc, extraction, ash, clorhidric acid.
extraction concentration by the concentration of the used
clorhidric acid solution, ash fraction, ratio Zn2+ : HCl, and
time of contact between ash and acid solution. Was
worked at various concentration of the clorhidric acid ( 5,
7.5, 10, 12.5, 15 and 20%), at various ratio Zn2+ : HCl (
1:1, 1:1.05, 1:1.1, 1:1.15, 1:1.2) and at two times of contact
that of 15 and 30 minutes.
1. Introduction
Zinc is essential to modern society. It is used
everywhere: as anti-corrosion coating on steel, for the
manufacture of precision components, as a construction
material, for the production of brass and rubber, in
pharmaceutical and cosmetics products, in fertilizers and
food supplements [1]. Galvanizing – the production of steel
against corrosion by metallurgical bonding zinc to steel is
the most important application of zinc.
At present, approximately 70% of the zinc produced
worldwide originates from mined ores and 30% from
recycled or secondary zinc [2]. Zinc is recycled at all stages
of production and use - for example, from scrap that arises
during the production of galvanized steel sheet, from scrap
generated during manufacturing and installation process,
and from end-of – life products. [3, 4, 5].
In thermal zinc coating industry results zinc ash which
contains almost 80 % zinc. This can be recovered under
different
forms
by
pyrometallurgical
and
hydrometallurgical processes [6, 7].
In this paper was made studies regarding the recover of
zinc from zinc ash resulted during thermal zinc coating by
extraction with clorhidric acid solutions in the view of the
zinc chloride solution obtaining which can be used at the
obtaining of the flux solutions. Was followed the
establishment of the optimum conditions of metals ions
extraction to obtain a solution with a concentration of ≈
200 g/L Zn2+.
3. Results and discussion
3.1. The analyze of zinc ash
The zinc ash sorted in those 4 fractions was analyzed
in the view of their composition establishment and the
experimental data are presented in table 1.
TABLE 1. The composition of the zinc ash
Fraction
1
2
3
4
Zn
78
85.8
86.2
87.38
Metals ions concentration, %
Fe
Ca
0.51
0.07
0.51
0.08
0.52
0.1
0.53
0.13
Pb
1.25
2.38
2.27
2.04
From the experimental data we can observe that all for
fractions have almost the same composition, it can be
observed only a small increasing of the zinc concentration
with the increasing of the ash fraction.
2. Experimental
3.2. The metals ions extraction concentration at the time of
15 minutes
The zinc ash resulted from thermal zinc coating
industry, was sorted in 4 fractions (1<0.315 mm, 2= 0.3151.25, 3=1.25-2, 4=2-6.3), which were analyzed in the view
of their composition establish.
To establish the optimum condition of metals ions
extraction was followed the dependence of the metals ions
The experimental data regarding the dependence of the
metals ions extraction concentration by the used clorhidric
acid solution concentration and by ash fraction at the time
of contact between acid and ash of 15 minutes are
presented in figure 1- 4.
71
Chem. Bull. "POLITEHNICA" Univ. (Timişoara)
Volume 51(65), 1-2, 2006
lnz=a+blnx+cy
z=a+bx+cy
Zn extraction concentration, g/L
200
150
175
125
150
100
125
75
100
50
25
75
50
25
0
5
1.
2
2.5
10
7.5
3
Ash fr
ac tio n
3.5
5
15
12 .5
lc
HC
2
4 .5
0
17 .5
n
ce
on
t
tra
70
Pb extraction concentration, mg/L
175
Zn extraction concentration, g/L
200
,%
ion
60
70
50
60
40
50
30
40
20
30
10
20
10
0
5
1.
2
5
2.
Ash fr
ac tio
n
880
660
660
440
440
220
220
2
5
2.
Ash fr
ac tio
n
3
5
3.
15
12 .5
5
4
l
HC
2.5
0
17 .5
Fe extraction concentration, mg/L
880
4
l
HC
2.5
nc
co
3.3. The metals ions extraction concentration at the time of
30 minutes
The experimental data regarding the dependence of the
metals ions extraction concentration by the used clorhidric
acid solution concentration and by ash fraction at the time
of contact between acid and ash of 30 minutes are
presented in figure 5-8.
%
n,
t io
a
tr
en
nc
co
Fig 2. The Fe extraction concentration
z=a+bx+cy
r 2=0.99798958 a=-6.2641667 b=-1.3523333 c=9.8453571
lnz=a+bx2 +cy0.5
60
70
50
60
40
50
30
40
20
30
10
20
10
0
5
1.
2
Ash
5
2.
frac ti
on
10
7.5
3
5
3.
5
4
2.5
15
12 .5
l
HC
0
17 .5
nc
co
Ca extraction concentration, mg/L
70
Zn extraction concentration, g/L
200
%
n,
t io
ra
t
en
175
200
150
175
125
150
100
125
75
100
50
75
50
25
5
1.
2
Ash
Fig.3. The Ca extraction concentration
frac ti
5
2.
on
3
5
5
3.
4
10
7.5
2.5
Fig.5. The Zn extraction concentration
72
15
12 .5
l
HC
25
17 .5
nc
co
Zn extraction concentration, g/L
r2=0.98110734 a=1.345541 b=-0.035370869 c=0.65767838
Ca extraction concentration, mg/L
Fe extraction concentration, mg/L
1100
1100
10
7.5
5
5
3.
%
n,
t io
ra
t
en
From the experimental data can be observed that the
metal ions extraction concentration degrees with the
increasing of the fraction and increase with the increasing
of the clorhidric acid concentration. Can be observed that at
the first ash fraction and at the concentration of 20% of the
clorhidric acid is obtained a solution which contain
180
g/L Zn2+.
z=a+bx+cy
r2=0.98104168 a=46.562 b=-73.139 c=50.693471
5
1.
3
15
12 .5
Fig. 4. The Pb extraction concentration
Fig.1. The Zn extraction concentration
0
10
7.5
0
17 .5
Pb extraction concentration, mg/L
r2=0.97316901 a=3.255119 b=-0.61104863 c=0.051094364
r2=0.9930688 a=-0.859 b=-6.9635 c=9.3017714
%
n,
tio
ra
t
en
Chem. Bull. "POLITEHNICA" Univ. (Timişoara)
Volume 51(65), 1-2, 2006
From the experimental data can be observed that in the
case of the contact time between ash and acid solution of
30 minutes the metal ions extraction concentration degrees
also with the increasing of fraction and increase with the
increasing of the acid concentration, but is obtained
extractions concentrations higher than in the case of the
contact time of 15 minutes.
So it is considered that the work conditions to obtain a
solution with a concentration of ≈ 200 g/L Zn is that of
using for extraction a solution of clorhidric acid with a
concentration of 20% at a contact time of 30 minutes.
z=a+bx+cy
980
980
760
760
540
540
320
320
100
17 .5
100
5
1.
2
10
7.5
5
2.
3
5
5
3.
Ash fr
ac tio
n
4
15
12 .5
l
HC
2.5
co
nc
3.4. The variation of the metals ions extraction
concentration versus the ratio Zn2+: HCl
%
n,
t io
ra
t
en
The experimental data regarding the dependence of the
metal ions extraction concentration by the fraction and by
the ratio Zn2+:HCl in the case of use for extraction a 20%
clorhidric acid solution at a contact time of 30 minutes are
presented in figures 9-12.
Fig 6. The Fe extraction concentration
lnz=a+bx+clny
r 2=0.99596553 a=1.0150395 b=-0.19346937 c=1.1932304
z=a+bx+cy
5
4
l
HC
2.5
c
Zn extraction concentration, g/L
180
150
170
140
160
%
n,
t io
a
r
nt
ce
on
2
150
3
140
4
Ratio HCl : Zn2+
Fig.7. The Ca extraction concentration
Fig.9. The Zn extraction concentration
z=a+b/x0.5 +cy
z=a+bx+cy
r2=0.96996547 a=-33.230019 b=66.703875 c=1.8280571
60
70
50
60
40
50
30
40
20
30
20
10
5
2
2.
Ash fr
ac tio
n
5
10
7.5
3
5
3.
5
4
2.5
15
12 .5
l
HC
10
17 .5
t
en
nc
co
t
ra
Fe extraction concentration, mg/L
Pb extraction concentration, mg/L
70
80
Pb extraction concentration, mg/L
r 2=0.98788043 a=1911.803 b=-109.2544 c=-722.64
80
1.
1.1
5
3.
190
160
5
1.0
3
200
170
1
5
2.
Ash fr
ac tio
n
180
Zn extraction concentration, g/L
2
15
12 .5
190
5
1.1
10
7.5
200
,%
i on
1200
1100
1200
1000
1100
900
1000
800
900
700
800
600
As
h
700
2
fra
cti
600
on
3
4 1
1.
05
1.
1
1.
15
Ratio HCl : Zn2+
Fig 10. The Fe extraction concentration
Fig. 8. The Pb extraction concentration
73
Fe extraction concentration, mg/L
5
1.
90
80
70
60
50
40
30
20
10
0
17 .5
n
tio
rac
hf
As
90
80
70
60
50
40
30
20
10
0
Ca extraction concentration, mg/L
r 2=0.98356821 a=352.4945 b=-3.1494 c=-158.515
Ca extraction concentration, mg/L
Fe extraction concentration, mg/L
1200
1200
Fe extraction concentration, mg/L
r2=0.98143096 a=77.733833 b=-71.081833 c=51.078029
Chem. Bull. "POLITEHNICA" Univ. (Timişoara)
Volume 51(65), 1-2, 2006
concentration of Zn is not necessary to use the clorhidric
acid in excess. It is considered the optimum work
conditions the ratio Zn2+ : HCl = 1:1.
z=a+blnx+cy
4. Conclusions
85
76
85
67
76
58
67
49
58
40
49
As
h
2
fra
cti
on
40
3
4 1
1.
05
1.
1
1.
15
Ca extraction concentration, mg/L
Ca extraction concentration, mg/L
r 2=0.98749839 a=120.84831 b=-21.734449 c=-41.77
In this paper was followed the establishment of the
optimum work condition of metals ions extraction from
zinc ash resulted from thermal zinc coating industry to
obtain a solution with a concentration of 200 g/L Zn2+.
From the experimental data can be observed that the
metals ions extraction concentration is influenced by the
studied parameters, these decrease with the increasing of
ash fraction, and of the ratio Zn2+:HCl, and increase with
the increasing of the clorhidric acid concentration and with
the increasing of contact time. The optimum work
conditions are considered to be:
- the ash fraction that is < 0.315 mm;
- the clorhidric acid solution concentration = 20%,
- time of contact 30 min;
- the ratio Zn2+: HCl = 1:1.
In this way is reduce the quantity of wastes resulted
from thermal zinc coating industry and the zinc ions are
recovered and put in good use by obtaining of zinc chloride
solution which can be use to the obtaining of the flux
solution and so the zinc ions which were a wastes are
reintroduce in the technological flux.
Ratio HCl : Zn2+
Fig.11. The Ca extraction concentration
lnz=a+bx1.5 +c(lnx)2
80
80
70
70
60
60
50
50
40
40
30
30
20
20
2
Ash
frac
tio n
1. 1
3
1.1
5
1.0
5
Pb extraction concentration, mg/L
Pb extraction concentration, mg/L
r 2=0.96081297 a=5.0815574 b=-0.86803117 c=2.7160882
References
1. F. Porter, Zinc Handbook, 1991.
2. M. Martin, R. Wildt, An Introduction to Recycling Zinc Coated Steel,
IZA, 2001.
3. K. Mager et al., Recovery of Zinc Oxide from Secondary Rpw
Materials, Fourth International Symposium on Recycling of Metals and
Engineered Materials, 2000, p. 329-344.
4. M. A. Rabah, A.S. El-Sayed, Recovery of zinc and some of its valuable
salts from secondary resources and wastes, Hydrometallurgy 37, 1995, p.
23-32.
5. European Zinc Institute, Zinc Recycling , EZI Publ. Brussels, 1990.
6. Gustavo Rossini, Andreea MOura Bernades, Galvanic sludge metals
recovery by pyrometallurgical and hydrometallurgical treatment, Journal
of Hazardous Materials, 131(1-3), 2006, pag. 210-216.
7. P. Dvorak, J. Jandova, Hydrometallurgical recover of zinc from hot dib
galvanizing ash, Hidrometallurgy, 77(1-2), 2005, pag. 29-33.
Ratio HCl : Zn2+
4 1
Fig. 12. The Pb extraction concentration
From the experimental data can be observed that the
metals ions extraction concentration degrees with the ash
fraction increasing and with the increasing of the ratio
Zn2+ : HCl. So to obtain a solution with a higher
74