1477
Characterization of Carbonaceous Matter to Assess its Influence
on Metallurgical Responses in Polymetallic Complex Ores
Janet Baron, Catherine Dunn, Jennifer Thogerson, Juan Alcalde, Daniel Lopez
Newmont Corporation
ABSTRACT: The presence of carbonaceous material in ores presents a challenge to flotation and conventional
gold processing technologies. Historically, spectroscopy-based methods have been employed to characterize
carbon polymorphs by correlating carbon crystallinity to metallurgical response and gold robbing parameters.
This correlation is not well-defined for complex polymetallic ores with typically lower gold concentrations, and
the detrimental effects of the carbonaceous material are observed not only in the extraction processes but also on
mineral beneficiation. In this paper, advances in the methods for characterization of carbonaceous matter were
reviewed and applied to a polymetallic complex ore deposit.
INTRODUCTION
Carbonaceous matter (CM) is a term widely utilized to
refer to the different forms of carbon compounds, such as
graphite, organic acids, humic substances and kerogen, that
are present in many gold ore deposits around the world
(Miller, Wan and Diaz 2016). Some forms of CM have a
significant impact on the metallurgical performance of gold
ores due to its affinity for the gold-cyanide complex. This is
when the CM acts as activated carbon adsorbing the com-
plex and therefore reducing the ability to extract gold in a
typical cyanide-based process. Additional challenges with
gold extraction occur when the CM represents one of the
gold carriers, as seen in some Carlin-type deposits (Baron,
Choi and Jeffrey, 2016).
The characteristics of CM have been extensively studied
trying to find correlations between structure, or other car-
bon properties, and the extent of gold robbing. Gold rob-
bing is typically determined by testing synthetic solutions
containing a gold complex or by analysis of bench top leach
tests in the presence of ores with varying amounts of CM
(Stenebråten et al.1999, Helm et al. 2009). Many of these
studies have focused on gold extraction where components
in the ore can cause refractoriness towards cyanidation,
such as the presence of sulfides with gold as either micro
inclusions or in solid solution that are removed by pretreat-
ment via pressure oxidation or roasting. The impacts of CM
in the processing of complex polymetallic sulfide deposits
can be more difficult to characterize. Typical flowsheets for
these types of deposits include multiple steps of flotation
to concentrate the sulfide minerals of interest (for example:
lead and zinc) and a flotation tails leach step for gold extrac-
tion. In this case, the detrimental effects of the CM are
observed not only in the extraction processes but also on
the flotation steps, causing higher reagent consumption,
slower kinetics and diluted concentrate grades due to its
natural hydrophobic characteristics (Jankolovits, Reyes and
Santana, 2020. Lind, Tomlinson and Awmack, 2018).
In recent years, new methods and approaches have
been developed to improve the characterization of CM in
complex ores, taking into account not only the structural
properties but also the mineralogical, chemical, and tex-
tural aspects. The combination of these methods with the
Characterization of Carbonaceous Matter to Assess its Influence
on Metallurgical Responses in Polymetallic Complex Ores
Janet Baron, Catherine Dunn, Jennifer Thogerson, Juan Alcalde, Daniel Lopez
Newmont Corporation
ABSTRACT: The presence of carbonaceous material in ores presents a challenge to flotation and conventional
gold processing technologies. Historically, spectroscopy-based methods have been employed to characterize
carbon polymorphs by correlating carbon crystallinity to metallurgical response and gold robbing parameters.
This correlation is not well-defined for complex polymetallic ores with typically lower gold concentrations, and
the detrimental effects of the carbonaceous material are observed not only in the extraction processes but also on
mineral beneficiation. In this paper, advances in the methods for characterization of carbonaceous matter were
reviewed and applied to a polymetallic complex ore deposit.
INTRODUCTION
Carbonaceous matter (CM) is a term widely utilized to
refer to the different forms of carbon compounds, such as
graphite, organic acids, humic substances and kerogen, that
are present in many gold ore deposits around the world
(Miller, Wan and Diaz 2016). Some forms of CM have a
significant impact on the metallurgical performance of gold
ores due to its affinity for the gold-cyanide complex. This is
when the CM acts as activated carbon adsorbing the com-
plex and therefore reducing the ability to extract gold in a
typical cyanide-based process. Additional challenges with
gold extraction occur when the CM represents one of the
gold carriers, as seen in some Carlin-type deposits (Baron,
Choi and Jeffrey, 2016).
The characteristics of CM have been extensively studied
trying to find correlations between structure, or other car-
bon properties, and the extent of gold robbing. Gold rob-
bing is typically determined by testing synthetic solutions
containing a gold complex or by analysis of bench top leach
tests in the presence of ores with varying amounts of CM
(Stenebråten et al.1999, Helm et al. 2009). Many of these
studies have focused on gold extraction where components
in the ore can cause refractoriness towards cyanidation,
such as the presence of sulfides with gold as either micro
inclusions or in solid solution that are removed by pretreat-
ment via pressure oxidation or roasting. The impacts of CM
in the processing of complex polymetallic sulfide deposits
can be more difficult to characterize. Typical flowsheets for
these types of deposits include multiple steps of flotation
to concentrate the sulfide minerals of interest (for example:
lead and zinc) and a flotation tails leach step for gold extrac-
tion. In this case, the detrimental effects of the CM are
observed not only in the extraction processes but also on
the flotation steps, causing higher reagent consumption,
slower kinetics and diluted concentrate grades due to its
natural hydrophobic characteristics (Jankolovits, Reyes and
Santana, 2020. Lind, Tomlinson and Awmack, 2018).
In recent years, new methods and approaches have
been developed to improve the characterization of CM in
complex ores, taking into account not only the structural
properties but also the mineralogical, chemical, and tex-
tural aspects. The combination of these methods with the