XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 3065
leaching campaigns, positively contributing to subsequent
processing stages after flotation. These efforts were essen-
tial in optimizing the overall efficiency of the ore treatment
process.
MATERIALS AND METHODS
Each phase is described in detail in the sections that follow.
Process Laboratory
Flotation tests were conducted on samples collected from
the plant’s hydrocyclone overflow during periods spaced
between June and August 2022, featuring slightly higher
sulfur concentrations in the plant feed, designated as tests
1, 2, and 3. The tests were based on the configuration com-
monly employed by Boliden Mineral AB, representing
the observed residence time in the plant for the rougher-
scavenger circuit and cleaner circuit presented for Åkulla
Kankberg ore. Outotec GTK automatic lab cells, 8-L for
rougher, and 4-L using the rougher concentrate for sub-
sequent cleaning flotation stages were utilized for the flo-
tation tests. Xanthate (74% potassium isopentyl xanthate,
17% potassium methyl-butyl xanthate) and Hostaflot
7869 (30–50% dithiophosphate, 25–30% thiocarba-
mate) served as collectors, while Aerophine 3418 (sodium
diisobutyldithiophosphinate) was considered a potential
alternative. Sodium bisulfite was used as a pH modifier at
10, and sulphuric acid was employed to achieve a mini-
mal pH reduction to 7. Dowfroth 250 (glycol) was utilized
as the frother. Samples were analyzed via XRF for semi-
quantitative evaluation of the results.
Industrial Plant
Between May 16 and June 11, 2023, Boliden conducted a
plant trial for Åkulla Kankberg ore to assess the effective-
ness of AEROPHINE ® 3418A (sodium diisobutyldithio-
phosphinate) as a replacement for PAX (74% potassium
isopentyl xanthate, 17% potassium methyl-butyl xan-
thate). The trial followed a structured 3 days ON – 3 days
OFF plan. During ON periods, Aerophine 3418A and a
lower PAX dosage were used, while OFF periods used PAX
and Hostaflot 7869 (30–50% dithiophosphate, 25–30%
thiocarbamate). The evaluation included daily balances
and chemical composition analysis (Au/Ag by FAAS, Te
by ICP) by Boliden’s chemical lab. A similar campaign ran
from December 10 to December 29, 2023, with sampling
campaigns and analyses at ALS-Sweden’s lab. The figure
below presents a flotation plant diagram with the process
flows considered in this evaluation.
Figure 3. Gold Recovery as a Function of Gold Grade in Plant Feed and Sulfur Grade in Ore Feed (2012-2023)
leaching campaigns, positively contributing to subsequent
processing stages after flotation. These efforts were essen-
tial in optimizing the overall efficiency of the ore treatment
process.
MATERIALS AND METHODS
Each phase is described in detail in the sections that follow.
Process Laboratory
Flotation tests were conducted on samples collected from
the plant’s hydrocyclone overflow during periods spaced
between June and August 2022, featuring slightly higher
sulfur concentrations in the plant feed, designated as tests
1, 2, and 3. The tests were based on the configuration com-
monly employed by Boliden Mineral AB, representing
the observed residence time in the plant for the rougher-
scavenger circuit and cleaner circuit presented for Åkulla
Kankberg ore. Outotec GTK automatic lab cells, 8-L for
rougher, and 4-L using the rougher concentrate for sub-
sequent cleaning flotation stages were utilized for the flo-
tation tests. Xanthate (74% potassium isopentyl xanthate,
17% potassium methyl-butyl xanthate) and Hostaflot
7869 (30–50% dithiophosphate, 25–30% thiocarba-
mate) served as collectors, while Aerophine 3418 (sodium
diisobutyldithiophosphinate) was considered a potential
alternative. Sodium bisulfite was used as a pH modifier at
10, and sulphuric acid was employed to achieve a mini-
mal pH reduction to 7. Dowfroth 250 (glycol) was utilized
as the frother. Samples were analyzed via XRF for semi-
quantitative evaluation of the results.
Industrial Plant
Between May 16 and June 11, 2023, Boliden conducted a
plant trial for Åkulla Kankberg ore to assess the effective-
ness of AEROPHINE ® 3418A (sodium diisobutyldithio-
phosphinate) as a replacement for PAX (74% potassium
isopentyl xanthate, 17% potassium methyl-butyl xan-
thate). The trial followed a structured 3 days ON – 3 days
OFF plan. During ON periods, Aerophine 3418A and a
lower PAX dosage were used, while OFF periods used PAX
and Hostaflot 7869 (30–50% dithiophosphate, 25–30%
thiocarbamate). The evaluation included daily balances
and chemical composition analysis (Au/Ag by FAAS, Te
by ICP) by Boliden’s chemical lab. A similar campaign ran
from December 10 to December 29, 2023, with sampling
campaigns and analyses at ALS-Sweden’s lab. The figure
below presents a flotation plant diagram with the process
flows considered in this evaluation.
Figure 3. Gold Recovery as a Function of Gold Grade in Plant Feed and Sulfur Grade in Ore Feed (2012-2023)