Recovery of Sulfuric Acid from Liquid Effluents by … of Sulfuric Acid from Liquid Effluents by...
Transcript of Recovery of Sulfuric Acid from Liquid Effluents by … of Sulfuric Acid from Liquid Effluents by...
Recovery of Sulfuric Acid from Liquid
Effluents by Electrodialysis
Juan Patricio Ibáñez & Ana Karina VásquezDepartamento de Ingeniería Metalúrgica y de Materiales
Universidad Técnica Federico Santa María
Introduction (i)
H2SO4 important and costly reagent used during copper production, it
is present in almost all the liquid effluents of the extractive processes.
Effluents high acidity, high level of sulphate/bisulphate. Treatment of
these effluents solid wastes, which needs to be manage according to
the DS 148.
Bleeds for controlling impurities in EW and/or ER H2SO4 liqueurs,
which are not always treated but are diluted and returned to previous
processes or transformed in “disposable” effluents.
Lix-SX-EW requirement of H2SO4 ≈3.2 ton/ton of Cu
Cost of H2SO4 ≈120 US$/ton
Introduction (ii)
Deficit of ≈2 Mton of acid per year is projected until 2013 in Chile
Recocery of acid
Solvent Extraction (Cyanex 923, TEHA, etc.)
Ion Exchange (Anion resine, etc.)
Dialysis (anion membrane)
Alternative electro dialysis
Introduction (iii)
ED membrane separation technology in which ionized species are
transported through ion-exchange membranes by an external electric field.
Cation
Memb.
Anion
Memb.
M+
M+
MXM+MX
X-
X-
X-
X-X
-
M+
M+
Electrical Field
Working
Solution(X-, M+, MX)
Anion rich
SolutionCation rich
Solution
Cathode(SS 316-L)
Anode(Pb)
CM(Neosepta)
AM(Neosepta)
Chambers(Acrylic)
Cation Flux
Anion Flux
C
C
A
CA C
Experimental (i)
W
S
Experimental (ii)
WS1. H2SO4 180 g/L + Cu 40 g/L
2. H2SO4 90 g/L + Cu 20 g/L
3. H2SO4 50 g/L + Cu 10 g/L
4. H2SO4 180 g/L + Co 0.2 g/LAnalysismetals by AAS
acid by titration
A , AC, CC & C H2SO4 20 g/L < WS
Experimental conditions Time = 180 mim
i = 100, 300 & 700 A/m2
Results & Discussion (i)
CM CMAM AM
(A) (AC) (WS) (CC) (C)
+ -SO42-
HSO4-
H+
HSO4-
SO42-H+
H+ + HSO4- H2SO4 H+ + HSO4
- H2SO4
2H+ + SO42- H2SO4 2H+ + SO4
2- H2SO4
T ime, m in
0 50 100 150 200
H2S
O4,
mm
ol
0
10
20
30
40
50
60
70
80
100 A/m2
300 A/m2
700 A/m2
Results & Discussion (ii)
Effect of current density
Lineal behaviour…
↑i ↑H2SO4
i, A /m2
0 200 400 600 800
Re
co
ve
ry
H2S
O4,
mo
l/h
/m2
0
2
4
6
8
10
12
14
16
18
20
W S-3
W S-2
W S-1
Results & Discussion (iii)
Effect of electrolyte´s concentration
Lineal behaviour…
↑[H2SO4]
↓Recovery
?
V iscosity, cP
1.0 1.2 1.4 1.6 1.8
Re
co
ve
ry
H2S
O4,
mo
l/h
/m2
0
4
8
12
16
20
100 A/m2
300 A/m2
700 A/m2
Results & Discussion (iv)
Electrolyte´s viscosity
Results & Discussion (v)
Purity of H2SO4 recovered
i, A/m2
RecoveryWS-1Purity TCu Recovery
WS-4Purity TCox102
100 1.66 99.1 0.30 0.95 99.9 0.09
300 2.92 97.6 0.65 2.15 99.9 0.15
700 7.82 94.9 1.34 5.97 99.9 0.24
Recovery rate (mol/h/m2), putity (%) & Cu-Co Transport (mol/h/m2)
i, A /m2
0 200 400 600 800
SE
C,
kW
h/k
g
0
1
2
3
4
5
Results & Discussion (v)
SEC for H2SO4 recovery