2346 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
mineralogy techniques, along with consistent laboratory
testing procedures, for different ore types across different
deposits and locations, could also potentially be exploited
to improve understanding of the impact of different carbon
“types” from a physical (flotation) separation perspective.
DEVELOPMENT OF A FLOTATION
CHEMISTRY SOLUTION
The initial investigation into improving the flotation sepa-
ration of both lead and zinc for organic carbon contain-
ing ores, considered a number of different approaches to
remove the organic carbon, and limit its impact on the sub-
sequent flotation separations. The three main approaches
evaluated considered included:
• Size separation (cyclones, centrifuges)
• Density/Size separation (elutriation)
• Carbon pre-flotation optimization
• Carbon depression
A number of different plant samples obtained during a lim-
ited high organic carbon ore run were used in the initial
investigation. A systematic testing program was undertaken
alongside a trusted flotation chemistry vendor to leverage
industry available knowledge alongside the now improved
understanding of the likely impact of mineralogy. Note that
a range of chemistries (conventional and new) were explored
and were not limited to specific vendor chemistries.
The size and gravity separation studies were not suc-
cessful and subsequent test work focused mainly on either
carbon pre-flotation or depression as the best next opportu-
nities for improvement.
Results from the systematic flotation test work study,
confirmed the results from the mineralogy study, that it is
unlikely that a carbon pre-flotation separation would be
sufficiently successful. The gold losses into the carbon con-
centrate would be substantial and very little opportunity
existed to improve the carbon separation, likely due to the
fine size of the organic carbon and the characteristics of
the froth (even varying chemistry to consider carbon spe-
cific collectors and custom frother formulations), excessive
entrainment would overshadow any progress made in the
separation. However, it was clear that removal of even only
30% of the organic carbon in carbon pre-flotation, did
result in more stable lead and subsequent zinc flotation.
From the test work program, it was evident that a
different flotation approach, namely carbon depression
could be successful (Figures 5 and 6). While several differ-
ent types of flotation depressants were tested (from a few
different vendor sources), one of the depressants, Syensqo
AERO ® 641, that has found some application in industry
already, was ultimately selected as the most likely reagent to
pursue further in a plant trial. This depressant was paired
with an appropriate frother in order to limit competitive
adsorption. While the test work showed a quantitative ben-
efit from applying a carbon depression scheme, the visual
observation of the improved froth quality in lead flotation
(without carbon pre-flotation) was also a key result. Due
to the substantial differences in laboratory froth versus
plant froth properties, it was noted at the conclusion of
Figure 5. Organic carbon distribution—with and without carbon-pre-float and with corg depressant
mineralogy techniques, along with consistent laboratory
testing procedures, for different ore types across different
deposits and locations, could also potentially be exploited
to improve understanding of the impact of different carbon
“types” from a physical (flotation) separation perspective.
DEVELOPMENT OF A FLOTATION
CHEMISTRY SOLUTION
The initial investigation into improving the flotation sepa-
ration of both lead and zinc for organic carbon contain-
ing ores, considered a number of different approaches to
remove the organic carbon, and limit its impact on the sub-
sequent flotation separations. The three main approaches
evaluated considered included:
• Size separation (cyclones, centrifuges)
• Density/Size separation (elutriation)
• Carbon pre-flotation optimization
• Carbon depression
A number of different plant samples obtained during a lim-
ited high organic carbon ore run were used in the initial
investigation. A systematic testing program was undertaken
alongside a trusted flotation chemistry vendor to leverage
industry available knowledge alongside the now improved
understanding of the likely impact of mineralogy. Note that
a range of chemistries (conventional and new) were explored
and were not limited to specific vendor chemistries.
The size and gravity separation studies were not suc-
cessful and subsequent test work focused mainly on either
carbon pre-flotation or depression as the best next opportu-
nities for improvement.
Results from the systematic flotation test work study,
confirmed the results from the mineralogy study, that it is
unlikely that a carbon pre-flotation separation would be
sufficiently successful. The gold losses into the carbon con-
centrate would be substantial and very little opportunity
existed to improve the carbon separation, likely due to the
fine size of the organic carbon and the characteristics of
the froth (even varying chemistry to consider carbon spe-
cific collectors and custom frother formulations), excessive
entrainment would overshadow any progress made in the
separation. However, it was clear that removal of even only
30% of the organic carbon in carbon pre-flotation, did
result in more stable lead and subsequent zinc flotation.
From the test work program, it was evident that a
different flotation approach, namely carbon depression
could be successful (Figures 5 and 6). While several differ-
ent types of flotation depressants were tested (from a few
different vendor sources), one of the depressants, Syensqo
AERO ® 641, that has found some application in industry
already, was ultimately selected as the most likely reagent to
pursue further in a plant trial. This depressant was paired
with an appropriate frother in order to limit competitive
adsorption. While the test work showed a quantitative ben-
efit from applying a carbon depression scheme, the visual
observation of the improved froth quality in lead flotation
(without carbon pre-flotation) was also a key result. Due
to the substantial differences in laboratory froth versus
plant froth properties, it was noted at the conclusion of
Figure 5. Organic carbon distribution—with and without carbon-pre-float and with corg depressant