1792 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
gold, a higher extraction is required to make it more eco-
nomically viable. Therefore, it is often necessary to inten-
sify the leaching process. Mechanical activation is currently
the most widely used and the simplest and most efficient
enhancement method (Baláž, P., Dutková, E., 2009). It is
known through the study that higher gold extraction can
be obtained with the help of mechanical activation. For
the recovery of gold in the leach solution, activated car-
bon adsorption and replacement precipitation are the
most important methods in the gold production indus-
try. In comparison, replacement precipitation is the most
economical and suitable method in the cyanide-free gold
extraction system due to its simple operation, high recovery
rate and reusable leach solution (Azizitorghabeh, A., 2021
Li, J., et al., 2012).
The focus of this paper is on the efficient leaching of
gold from hard-to-leach gold ores after roasting treatment
using cyanide-free gold extraction, and at the same time
using mechanical activation to further improve the extrac-
tion of gold, and recovering the silver therein under the
premise of meeting the requirements of the gold extraction,
and then recovering the gold and silver from the leach solu-
tion using the replacement precipitation method.
MATERIALS AND METHOD
Materials
The test material in this study is a gold-rich roasting slag
that has been roasted and treated with a high content of
silver. Before cyanide-free leaching, the raw material was
treated by acid leaching to recover the base metals and
remove impurities as much as possible. The chemical com-
position of the raw material was analyzed, and the results
showed that the gold content of the raw material was 54.03
g/t, the silver content was 96.50 g/t, and the rest of the
main constituent elements were Fe, Si and Al, as shown in
Table 1. As shown in Figure 1, the physical composition of
the raw material is mainly iron trioxide, silica, calcium sul-
fate and sodium feldspar. Overall, the physical composition
of the raw material is not complex.
Gold Deportment Study
After roasting and acid leaching treatment of the test mate-
rial, gold mainly exists in the form of primary gold, with a
content as high as 50.80 g/t, accounting for about 93.42%
of the total gold content. After pre-enrichment by re-elec-
tion and other methods, microscopy and backscattering
test results show that the gold in the raw material is mainly
in iron oxide minerals, wrapped by iron oxide or hyphen-
ated with iron oxide, and the gold is mainly in granular or
irregular shape, as shown in Figure 2.
Experimental Procedure
Gold and Silver Leaching Test
The main target element recovered in this study is gold, so
the leaching of gold is mainly studied systematically in this
test, and the recovery of silver is only analyzed under the
premise of meeting the optimal extraction of gold. The gold
and silver leaching test are divided into two parts: conven-
tional stirring leaching and mechanical activation enhanced
leaching. The conventional stirred leaching test was carried
out in a 1.0 L beaker and stirred with a rotor stirrer, and
the raw material used in each test was 80 g. During the
test, the pH of the slurry was adjusted using dilute sulfuric
acid solution, and the corresponding leaching reagents were
added sequentially, such as sodium thiocyanate, manganese
dioxide, etc. Unlike the agitation leaching test, the mechan-
ically activated leaching test was carried out in a QM-3SP2
planetary ball mill, in which all the reagents including water
were placed in the ball mill’s ball mill jar, and the method
of “leaching while milling” was adopted, and in the process
of leaching, the ball mill jar rotated and autorotated at the
same time under a certain rate. At the end of the leaching
test, solid-liquid separation was carried out, and the leach-
ing residue was washed three times and then dried for gold
content analysis, and the gold in the leaching solution was
determined by atomic absorption spectrometry (AAS). All
leachate was collected and stored for subsequent gold and
Table 1. Chemical analysis of the raw sample, %
Au, g/t Ag, g/t Fe Si Al S K
54.03 96.50 31.90 14.88 4.34 1.71 1.63
Ca Mg Cu Zn As Pb Mn
1.35 0.38 0.49 0.21 0.17 0.65 0.01
Figure 1. Raw material XRD test results
gold, a higher extraction is required to make it more eco-
nomically viable. Therefore, it is often necessary to inten-
sify the leaching process. Mechanical activation is currently
the most widely used and the simplest and most efficient
enhancement method (Baláž, P., Dutková, E., 2009). It is
known through the study that higher gold extraction can
be obtained with the help of mechanical activation. For
the recovery of gold in the leach solution, activated car-
bon adsorption and replacement precipitation are the
most important methods in the gold production indus-
try. In comparison, replacement precipitation is the most
economical and suitable method in the cyanide-free gold
extraction system due to its simple operation, high recovery
rate and reusable leach solution (Azizitorghabeh, A., 2021
Li, J., et al., 2012).
The focus of this paper is on the efficient leaching of
gold from hard-to-leach gold ores after roasting treatment
using cyanide-free gold extraction, and at the same time
using mechanical activation to further improve the extrac-
tion of gold, and recovering the silver therein under the
premise of meeting the requirements of the gold extraction,
and then recovering the gold and silver from the leach solu-
tion using the replacement precipitation method.
MATERIALS AND METHOD
Materials
The test material in this study is a gold-rich roasting slag
that has been roasted and treated with a high content of
silver. Before cyanide-free leaching, the raw material was
treated by acid leaching to recover the base metals and
remove impurities as much as possible. The chemical com-
position of the raw material was analyzed, and the results
showed that the gold content of the raw material was 54.03
g/t, the silver content was 96.50 g/t, and the rest of the
main constituent elements were Fe, Si and Al, as shown in
Table 1. As shown in Figure 1, the physical composition of
the raw material is mainly iron trioxide, silica, calcium sul-
fate and sodium feldspar. Overall, the physical composition
of the raw material is not complex.
Gold Deportment Study
After roasting and acid leaching treatment of the test mate-
rial, gold mainly exists in the form of primary gold, with a
content as high as 50.80 g/t, accounting for about 93.42%
of the total gold content. After pre-enrichment by re-elec-
tion and other methods, microscopy and backscattering
test results show that the gold in the raw material is mainly
in iron oxide minerals, wrapped by iron oxide or hyphen-
ated with iron oxide, and the gold is mainly in granular or
irregular shape, as shown in Figure 2.
Experimental Procedure
Gold and Silver Leaching Test
The main target element recovered in this study is gold, so
the leaching of gold is mainly studied systematically in this
test, and the recovery of silver is only analyzed under the
premise of meeting the optimal extraction of gold. The gold
and silver leaching test are divided into two parts: conven-
tional stirring leaching and mechanical activation enhanced
leaching. The conventional stirred leaching test was carried
out in a 1.0 L beaker and stirred with a rotor stirrer, and
the raw material used in each test was 80 g. During the
test, the pH of the slurry was adjusted using dilute sulfuric
acid solution, and the corresponding leaching reagents were
added sequentially, such as sodium thiocyanate, manganese
dioxide, etc. Unlike the agitation leaching test, the mechan-
ically activated leaching test was carried out in a QM-3SP2
planetary ball mill, in which all the reagents including water
were placed in the ball mill’s ball mill jar, and the method
of “leaching while milling” was adopted, and in the process
of leaching, the ball mill jar rotated and autorotated at the
same time under a certain rate. At the end of the leaching
test, solid-liquid separation was carried out, and the leach-
ing residue was washed three times and then dried for gold
content analysis, and the gold in the leaching solution was
determined by atomic absorption spectrometry (AAS). All
leachate was collected and stored for subsequent gold and
Table 1. Chemical analysis of the raw sample, %
Au, g/t Ag, g/t Fe Si Al S K
54.03 96.50 31.90 14.88 4.34 1.71 1.63
Ca Mg Cu Zn As Pb Mn
1.35 0.38 0.49 0.21 0.17 0.65 0.01
Figure 1. Raw material XRD test results