XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 3021
cleaning using sulfuric acid washing, oxalic acid, Na2S and
use of DETA as an alternative depressant.
The cumulative mass pull, copper and zinc grade
and recoveries of the copper flotation section are given in
Figure 2. The copper and zinc grade and recoveries were
very low under the standard flotation conditions. The high
zinc and to some extent copper recoveries in the absence of
depressant were due to the very high mass pull to the con-
centrate. The use of 500 g/t oxalic acid improved the cop-
per and zinc recoveries but with no Cu/Zn selectivity. The
use of DETA provided better Cu/Zn selectivity compared
to the other test conditions, but it was still not satisfactory,
and the copper recovery was very low. The results of these
tests show clearly that the Cu/Zn selectivity could not be
improved by using different types of depressants in the flo-
tation stage. Therefore, an extreme surface cleaning stage
followed by selective flotation could be tested to solve the
selectivity problem.
Surface Cleaning by Cyanidation
The copper minerals, particularly the secondary copper
minerals, are soluble in cyanide solution to some extent.
Table 5 shows the percentage of CN soluble copper of the
copper minerals. The secondary copper minerals, particu-
larly chalcocite, are dissolved within minutes (Ferrer, et al.,
2021, Fisher et al, 1992 and 1994). The dissolution mecha-
nism of chalcocite in the presence of cyanide proceeds via
copper complexation under non-oxidative conditions, rep-
resented by the following equation:
Cu2S(s) +2nCN–(aq) =2[Cu(CN)(n)](n–1)– +S2– (1)
Zn Recovery (%)
Figure 1. Effects of the flotation reagent scheme on the copper-zinc selectivity of the sulfide ore and enriched ore
Table 4. The reagent schemes and flotation conditions tested
for the flotation of enriched ore
Test Code Test Conditions (Cu Rougher Flotation)
Std Cond D80=38 µm, 0.5 kg/t Na2S, 1 kg/t ZnSO
4 ,
3 kg/t MBS, 30 g/t D507E, 45 g/t MIBC,
pH 6.5, 9 min flotation
No Dep
(Nat pH)
Grinding at natural pH (pH 7), 120 g/t
Na-Aerofloat (dithiophosphate)
H2SO4
Washing
Grinding at natural pH, add 75 ml 10%
H2SO4 solution (pH 1.9), agitate for 30 min,
filter, repulping and addition of standard
flotation reagents.
Oxalic Acid
(500 g/t)
500 g/t Oxalic acid in the mill with standard
flotation reagents
Oxalic Acid
(200 g/t)
200 g/t Oxalic acid in the mill with standard
flotation reagents
Oxalic Acid
Wash-Deslime
500 g/t oxalic acid pre-treatment prior to
grinding, desliming, standard flotation
conditions
Desliming
(pre-grind)
Agitating –2 mm ore for 30 min, desliming,
standard flotation conditions
Na2S Cond
(pre-grind)
Agitating –2 mm ore with 1 kg/t Na2S for 30
min, desliming, standard flotation conditions
Na2S Cond
(post-grind)
Grinding at natural pH with 1 kg/t Na2S,
washing and filtration, standard flotation
conditions
DETA
Addition
Grinding under standard conditions,
conditioning with 100 g/t DETA, standard
flotation conditions
Cu
Recovery
(%)
cleaning using sulfuric acid washing, oxalic acid, Na2S and
use of DETA as an alternative depressant.
The cumulative mass pull, copper and zinc grade
and recoveries of the copper flotation section are given in
Figure 2. The copper and zinc grade and recoveries were
very low under the standard flotation conditions. The high
zinc and to some extent copper recoveries in the absence of
depressant were due to the very high mass pull to the con-
centrate. The use of 500 g/t oxalic acid improved the cop-
per and zinc recoveries but with no Cu/Zn selectivity. The
use of DETA provided better Cu/Zn selectivity compared
to the other test conditions, but it was still not satisfactory,
and the copper recovery was very low. The results of these
tests show clearly that the Cu/Zn selectivity could not be
improved by using different types of depressants in the flo-
tation stage. Therefore, an extreme surface cleaning stage
followed by selective flotation could be tested to solve the
selectivity problem.
Surface Cleaning by Cyanidation
The copper minerals, particularly the secondary copper
minerals, are soluble in cyanide solution to some extent.
Table 5 shows the percentage of CN soluble copper of the
copper minerals. The secondary copper minerals, particu-
larly chalcocite, are dissolved within minutes (Ferrer, et al.,
2021, Fisher et al, 1992 and 1994). The dissolution mecha-
nism of chalcocite in the presence of cyanide proceeds via
copper complexation under non-oxidative conditions, rep-
resented by the following equation:
Cu2S(s) +2nCN–(aq) =2[Cu(CN)(n)](n–1)– +S2– (1)
Zn Recovery (%)
Figure 1. Effects of the flotation reagent scheme on the copper-zinc selectivity of the sulfide ore and enriched ore
Table 4. The reagent schemes and flotation conditions tested
for the flotation of enriched ore
Test Code Test Conditions (Cu Rougher Flotation)
Std Cond D80=38 µm, 0.5 kg/t Na2S, 1 kg/t ZnSO
4 ,
3 kg/t MBS, 30 g/t D507E, 45 g/t MIBC,
pH 6.5, 9 min flotation
No Dep
(Nat pH)
Grinding at natural pH (pH 7), 120 g/t
Na-Aerofloat (dithiophosphate)
H2SO4
Washing
Grinding at natural pH, add 75 ml 10%
H2SO4 solution (pH 1.9), agitate for 30 min,
filter, repulping and addition of standard
flotation reagents.
Oxalic Acid
(500 g/t)
500 g/t Oxalic acid in the mill with standard
flotation reagents
Oxalic Acid
(200 g/t)
200 g/t Oxalic acid in the mill with standard
flotation reagents
Oxalic Acid
Wash-Deslime
500 g/t oxalic acid pre-treatment prior to
grinding, desliming, standard flotation
conditions
Desliming
(pre-grind)
Agitating –2 mm ore for 30 min, desliming,
standard flotation conditions
Na2S Cond
(pre-grind)
Agitating –2 mm ore with 1 kg/t Na2S for 30
min, desliming, standard flotation conditions
Na2S Cond
(post-grind)
Grinding at natural pH with 1 kg/t Na2S,
washing and filtration, standard flotation
conditions
DETA
Addition
Grinding under standard conditions,
conditioning with 100 g/t DETA, standard
flotation conditions
Cu
Recovery
(%)