XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 605
Ag/AgCl scale. To prevent diffusion of metal cations to the
counter-electrode compartment, the compartments were
separated by an anion-exchange membrane Sustainion ®
X37-50 grade 60 Membrane. More details are provided
elsewhere [25].
The tests were conducted on regenerated RVC elec-
trodes. The regeneration was acheived by the polarization
at +0.80 V in 0.1 M NaCl, pH 2.5, for 10 min [25, 27].
Elemental concentrations were measured using induc-
tively coupled plasma mass spectrometry (ICP-MS) using a
Perkin Elmer ELAN DRC IIa instrument after diluting the
samples 1:1 with 2% v/v HNO3.
The uptake (recovery) of each metal j is calculated as
Uptakej (%)=(1 – Ctj/C0j )× 100 (5)
where Ctj and C0j is the time-dependent and initial con-
centration (mg/L) of the metal in the solution, respectively.
The selectivity of the uptake reaction to a metal cation
j is characterized by the relative content (concentration) of
this cation in the deposit
Contentj (%)=Mj × 100/Mtotal,
where Mj and Mtotal is the weight of the metal cation j and
the weight of all metals in the deposit, respectively. It is
calculated as
Contentj (%)=Cj × 100/Ctotal, (6)
where Cj =C0j – Ctj is the decrease in the concentration
(mg/L) of the metal j in the solution during the uptake
reaction and Ctotal =Sj(C0j – Ctj) for all metals measured.
The specific recovery (uptake) rate SRR for a metal j is
calculated as
SRRj =mj/(WRVC × tlinear), (7)
where mj (mg) is the weight of the metal j deposited on the
electrode during the linear segment of the uptake kinetic
curve tlinear (min) and WRVC (g) is the weight of the RVC
electrode.
The water treatment rate WTR is calculated as
WTR =Vcell/(WRVC × ttotal), (8)
where Vcell (L) is the volume of the working compartment
of the cell, WRVC (kg) is the weight of the RVC electrode,
and ttotal (min) is the time when the uptake kinetic curve
approaches the plateau.
RESULTS AND DISCUSSION
The composition of the three AMD samples used in this
study is shown in Table 1. These samples were collected
from three different water streams within Boliden’s mine
areas. Each mining water was collected without headspace
in a 1-L polyethylene bottle, stored in darkness at room
temperature, and tested within 2–6 weeks after collection.
All three samples were selected due to their relatively low
content of Fe, while one sample, in addition, has no Al.
It was expected that precipitation of Fe and Al impedes
the recovery of ultradilute REE, Co, and Ni due to their
adsorption on the precipitated colloids.
The first sample (called AMD1 hereafter) is mildly
acidic (pH 4.7). Its main economically attractive compo-
nents include 32.2 mg/L Cu, 7.1 mg/L Zn, 2.0 mg/L Co,
0.5 mg/L Ni, and 3.3 mg/L of total REE (TREE) (Ce,
La, Nd, and Y). This water is very hard due to the high
concentrations of Ca (350 mg/L), Mg (150 mg/L), and
SO42– (480 mg/L). In addition, it contains 30 mg/L Mn,
c a b
Figure 2. The experimental setup: (a) a two-compartment 40-mL electrolytic cell with a RVC working electrode, a Pt counter
electrode, Ag/AgCl reference, and a glass pH electrode, (b) the bench-top setup, and (c) SEM image of a 100-ppi RVC.
Copyright © 2023 Chernyshova, Suup, Kihlblom, Kota, Ponnurangam
Ag/AgCl scale. To prevent diffusion of metal cations to the
counter-electrode compartment, the compartments were
separated by an anion-exchange membrane Sustainion ®
X37-50 grade 60 Membrane. More details are provided
elsewhere [25].
The tests were conducted on regenerated RVC elec-
trodes. The regeneration was acheived by the polarization
at +0.80 V in 0.1 M NaCl, pH 2.5, for 10 min [25, 27].
Elemental concentrations were measured using induc-
tively coupled plasma mass spectrometry (ICP-MS) using a
Perkin Elmer ELAN DRC IIa instrument after diluting the
samples 1:1 with 2% v/v HNO3.
The uptake (recovery) of each metal j is calculated as
Uptakej (%)=(1 – Ctj/C0j )× 100 (5)
where Ctj and C0j is the time-dependent and initial con-
centration (mg/L) of the metal in the solution, respectively.
The selectivity of the uptake reaction to a metal cation
j is characterized by the relative content (concentration) of
this cation in the deposit
Contentj (%)=Mj × 100/Mtotal,
where Mj and Mtotal is the weight of the metal cation j and
the weight of all metals in the deposit, respectively. It is
calculated as
Contentj (%)=Cj × 100/Ctotal, (6)
where Cj =C0j – Ctj is the decrease in the concentration
(mg/L) of the metal j in the solution during the uptake
reaction and Ctotal =Sj(C0j – Ctj) for all metals measured.
The specific recovery (uptake) rate SRR for a metal j is
calculated as
SRRj =mj/(WRVC × tlinear), (7)
where mj (mg) is the weight of the metal j deposited on the
electrode during the linear segment of the uptake kinetic
curve tlinear (min) and WRVC (g) is the weight of the RVC
electrode.
The water treatment rate WTR is calculated as
WTR =Vcell/(WRVC × ttotal), (8)
where Vcell (L) is the volume of the working compartment
of the cell, WRVC (kg) is the weight of the RVC electrode,
and ttotal (min) is the time when the uptake kinetic curve
approaches the plateau.
RESULTS AND DISCUSSION
The composition of the three AMD samples used in this
study is shown in Table 1. These samples were collected
from three different water streams within Boliden’s mine
areas. Each mining water was collected without headspace
in a 1-L polyethylene bottle, stored in darkness at room
temperature, and tested within 2–6 weeks after collection.
All three samples were selected due to their relatively low
content of Fe, while one sample, in addition, has no Al.
It was expected that precipitation of Fe and Al impedes
the recovery of ultradilute REE, Co, and Ni due to their
adsorption on the precipitated colloids.
The first sample (called AMD1 hereafter) is mildly
acidic (pH 4.7). Its main economically attractive compo-
nents include 32.2 mg/L Cu, 7.1 mg/L Zn, 2.0 mg/L Co,
0.5 mg/L Ni, and 3.3 mg/L of total REE (TREE) (Ce,
La, Nd, and Y). This water is very hard due to the high
concentrations of Ca (350 mg/L), Mg (150 mg/L), and
SO42– (480 mg/L). In addition, it contains 30 mg/L Mn,
c a b
Figure 2. The experimental setup: (a) a two-compartment 40-mL electrolytic cell with a RVC working electrode, a Pt counter
electrode, Ag/AgCl reference, and a glass pH electrode, (b) the bench-top setup, and (c) SEM image of a 100-ppi RVC.
Copyright © 2023 Chernyshova, Suup, Kihlblom, Kota, Ponnurangam