American Journal of Applied Science and Technology
25
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VOLUME
Vol.05 Issue 03 2025
PAGE NO.
25-30
10.37547/ajast/Volume05Issue03-05
Study Of Gravity Separation Enrichment And Material
Composition Of Stockpiled Technogenic Waste From
The Marjanbulak Gold Extraction Plant
Sagdieva M.G.
SI “IMR”, senior research fellow, Uzbekistan
E.Yu. Jabborov
SI “IMR”, junior researcher, Uzbekistan
M.Z. Abdikarimov
SI “IMR”, junior researcher, Uzbekistan
A.A. Normurodov
SI “IMR”,(PhD) junior researcher, Uzbekistan
A.S. Usmonov
SI “IMR”, junior researcher, Uzbekistan
Received:
03 January 2025;
Accepted:
05 February 2025;
Published:
13 March 2025
Abstract:
Laboratory studies were conducted, the purpose of which was to study the material composition of the
lying tailings of the Marjanbulak Gold Extraction Workshop (MZITS). The material composition of the sample was
analyzed by spectral, chemical, atomic-absorption, test, mineralogical, rational, granulometric, and other analysis
methods. According to the results of chemical analyses, the average gold content in the sample was 0.61 U.U. and
silver 11.61 U.U. The technological sample of tailings belongs to the mixed (oxidized and sulfide-quartz) type.
Valuable components of tailings are gold and silver. Characteristic features of gold, influencing the technology of
enrichment: the form of gold occurrence is native and in the form of electrum in goethite (oxidized part). Perhaps
the isolated native gold is found in quartz, and in In sulfides, it is invisible; in terms of reflectivity, gold is medium
and low-grade. The main non-metallic minerals are quartz, feldspars, carbonates, sericite, and chlorites. Accessory
minerals include apatite, rutile+ilmenite, and epidite. A factor negatively impacting tail enrichment is the high
content of micas - sericite (37%) and clay substances (7%). In terms of characteristic properties, quality, as well as
the quantity of ore minerals and noble metals, the waste from processing is significantly inferior to the initial ore,
which complicates the waste enrichment process and predetermines low technological indicators. According to the
results of a rational analysis, the content of "non-extractable" gold in quartz, aluminosilicates, and other acid-
insoluble minerals in the initial tailings is 32.79% and bound by sulfides 26.23%.
Keywords:
Gold, silver, element, valuable component, technogenic waste, secondary waste, spectral, complete
chemical, optical emission spectral, mineral.
Introduction:
Entrance: and over the past decades,
there has been a steady increase in global gold prices.
Especially during periods of political and economic
uncertainty, gold is considered a reliable and attractive
investment. For this reason, involving refractory gold-
bearing ores, as well as technogenic deposits, in
processing is a promising direction for the development
of the gold mining industry. In this regard, the need for
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American Journal of Applied Science and Technology (ISSN: 2771-2745)
the development and industrial implementation of
technologies for this type of raw material will remain
high. The technology and equipment used must not
only ensure high process efficiency and maximum
possible extraction indicators of the valuable metal
from the raw material, but also exclude exceeding the
maximum permissible emissions of harmful substances
into the environment, i.e., comply with the
requirements and norms for environmental protection,
operating at the work site and outside it. [13].
The current interest in technogenic mineral formations
and, in particular, in technogenic gold formations as
secondary metal concentrators is obvious, but the
problems and difficulties of involving technogenic
resources in industrial development are also evident.
Technogenic gold-bearing objects among other types
of mineral extraction and processing waste are the
most valuable, in-demand, investment-attractive, and
most prepared for recycling.
As a result, the technological properties of technogenic
gold will have significant differences compared to the
properties of gold in primary ores and placer deposits.
Such differences as an increase in the proportion of
free gold, an increase in the proportion of gold in
isometric-plate, rolled, and semi-rolled forms, the
concentration of metal as a result of its deposition from
solutions on geochemical barriers, as well as an
increase in gold content in the local volumetric areas of
the tailings pond, will be favorable factors for the
extraction of gold from the lying tailings. However, the
combined technological properties of technogenic gold
predetermine the low processing rates of waste using
traditional gravitational processes, flotation, and
cyanidation. [14].
In recent decades, there has been a reduction in
geological exploration of deposits in the gold mining
industry, a shortage of high-quality raw materials due
to a sharp decrease in readily available gold reserves in
primary ores and placer deposits, and the depletion of
reserve reserves of the ore base as a whole, which
negatively affects the volume of gold and silver
production. Currently, there is a large amount of
technogenic and secondary waste containing gold and
silver. Each type of such raw material requires a specific
approach to extracting precious metals due to the
peculiarities of the material composition and the form
in which gold is present.
Интенсивное
развитие
золотодобывающей
промышленности в предыдущие десятилетия
привело
к
накоплению
больших
объемов
техногенных отвалов, в которых содержится 0,5
-2,3
у/е золота. Недоизвлечение ценных компонентов
объясняется
несовершенством
технологий
извлечения золота из рудного сырья, таких как
гравитация, амальгамация, перколяция. Некоторые
хвостохранилища в настоящее время можно
рассматривать как отдельные месторождения [1].
Several types of technogenic and secondary raw
materials have been identified, which are produced by
four main complexes: mining and processing,
metallurgical, household, and energy. They are
conventionally divided into three large groups:
enrichment, hydrometallurgical (chemical action), and
pyrometallurgical (thermal action). Hydrometallurgical
methods (particularly cyanidation) are most actively
used, as they yield high gold recovery rates of 80-99%.
In turn, such methods often have a negative impact on
the environment, they are quite costly, time-
consuming, and have low extraction rates of micro- and
ultradisperse gold, the share of which is significant,
especially in the waste of mining and metallurgical
complexes. Enrichment methods, in turn, show the
effectiveness of extracting fine gold from mining and
processing complex waste [2].
The development of mining led to the formation of
large volumes of extraction and processing, followed by
the accumulation of waste: waste rock, poor ores,
tailings, etc. The storage of production waste in mining
enterprises, the volume of which is increasing every
year, occupies vast territories. This leads not only to the
disappearance of landscapes, but also to the pollution
of the environment. The basis of modern gold
hydrometallurgy is the cyanide process, which is
extremely widespread in domestic and foreign
industry. In practice, there is not a single enterprise in
the world that operates on the production of
commercial metal and does not undergo the stage of
cyanidation of ore or its processed products [3]. Due to
the depletion of placer gold and silver deposits,
modern and highly efficient extraction technologies are
necessary for processing raw materials with low
content of valuable components and complex
composition [10].
Developing and mastering the technology for
extracting gold from accumulated technogenic mineral
objects, primarily from tailings, waste, and water of
gold extraction plants and production facilities, is
becoming increasingly relevant for many gold mining
enterprises where the raw material reserves of
conditioned ores are close to depletion. [15].
Currently, the reserves of gold-bearing ores in the
Marjanbulak ore field are practically depleted, with the
volume of lying tailings in the No. 1 MGEP tailings
storage facility, accumulated between 1980 and 2017,
amounting to about 20 million tons. These technogenic
wastes can be considered as a raw material resource
for the Marjanbulak gold extraction plant in the near
future. To involve MSIC waste in processing, it is
necessary to develop a rational and comprehensive
technology for extracting gold for its processing under
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American Journal of Applied Science and Technology (ISSN: 2771-2745)
MGEP conditions.
Ore preparation is the initial and important stage in the
technology of processing gold-bearing raw materials
and gold-bearing technogenic waste. Ore preparation
includes sieving, crushing, grinding, and classification
operations. In laboratory studies, the mixing operation,
necessary for obtaining a representative sample of the
studied material, is added to the above-mentioned
operations, which is not insignificant, since gold is
unevenly distributed in the ore raw material.
The material composition of the MGEP waste sample
was studied using spectral, chemical, test, rational,
opto-emission spectral, mineralogical, and other types
of analyses. When conducting research, the processes
of selection, sampling, processing, and preparation of
samples, as well as the setting and interpretation of the
conducted experiments, are among the important
moments from which further research results depend.
The preparation of a representative sample of
technogenic gold-containing tailings from MGEP s was
carried out using the manual sampling method, which
consists of the following stages: sampling, averaging it
using the "ring and cone" method, and quartization [4].
Despite significant research on increasing the efficiency
of gold extraction, the flotation extraction of finely
dispersed gold associated with sulfides and quartz does
not exceed 60-80%, and in some cases 30-40%. Thus,
research on increasing the extraction of noble metals
from mineral raw materials is a pressing task.
Spectral analysis
The semi-quantitative spectral analysis was performed
in the laboratory of the Ministry of Health ofthe
Republic of Uzbekistan, the results of which are
presented in Table. 1.
Table 1
Results of spectral analysis of the average tail sample
Name
of elements
Quantity,
10
-3
%
Name
of
elements
Quantity,
10
-3
%
Name
of
elements
Quantity,
10
-3
%
Ba
30
Ni
2
Mn
100
Be
0,7
Sn
0,7
Cu
20
V
100
Pb
100
Mo
5
Bi
<0,2
Ag
10
As
<1,1
W
7
Sb
30
Nb
5
Ga
3
Ti
700
Ta
10
Ge
1
Cr
100
Li
<3
Cd
<0,1
Zn
100
Au
0,07
Co
5
Complete chemical analysis
Complete chemical analysis was performed in the laboratory of the Ministry of Higher and Secondary Specialized
Education of the Republic of Uzbekistan. The results of which are presented in the State Unitary Enterprise "IMR"
Table. 2.
Table 2
Chemical analysis results of the average waste sample
Name
of elements
Quantity, %
Name
of elements
Quantity, %
Name
of elements
Quantity, %
SiО
2
65,7
Na
2
O
0,46
Al
2
О
3
14,2
Fe
2
О
3
9
K
2
O
2,96
CaO
1,95
FeО
2,27
S
COM.
2,04
MgO
1,60
TiO
2
0,59
SО
3
2,32
Н
2
О
0,16
MnO
0,09
S
1,11
M.L.P.
4,58
СО
2
3,74
Optical emission spectral analysis
Table 3
Results of optical emission spectral analysis of the initial tailings
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American Journal of Applied Science and Technology (ISSN: 2771-2745)
№ Elements
Quantity,
u/c
№ Elements
Quantity,
u/c
№
Elements
Quantity,
u/c
1
Ag
3,42
21
Na
8290
31
Fe
48300
2
Al
65600 22
Nb
14,1
32
Gd
19,9
3
As
546
23
Nd
26,4
33
Gа
19,9
4
Au
0,663 24
Ni
51,2
34
Hf
1,85
5
Ba
914
25
P
503
35
Ho
0,527
6
Be
2,39
26
Pb
13,3
36
In
0,221
7
Bi
1,64
27
Pr
6,15
37
K
28700
8
Ca
5090
28
Rb
63,5
38
La
28,8
9
Cd
0,1
29
S
19900
39
Li
15,5
10
Ce
62,5
30
Sb
0,674
40
Lu
0,323
11
Co
17,2
21
Sc
12,5
41
Mg
6550
12
Cr
178
22
Se
12,5
42
Mn
743
13
Cs
7,95
23
Sm
4,19
43
Mo
22,9
14
Cu
24,3
24
Sn
4,96
44
Te
0,129
15
Dy
3,44
25
Sr
152
45
Th
9,2
16
Er
2,61
26
Ta
0,375
46
Ti
3220
17
Eu
1,04
27
Tb
0,1
47
Tl
0,469
18
Tm
0,292
28
W
3,1
48
Zn
265
19
U
3,68
29
Y
18,4
49
Zr
86,2
20
V
148
30
Yb
2,1
50
∑REE
169,2
According to the results of the optical emission spectral
analysis of the initial tailings, the content of rare earth
elements (RZE) was 169.2 units/ha, the main part of
which belongs to the light RZE group. Industry
requirements for rare earth raw materials have
fundamentally changed over the past 10 years. If until
the beginning of the 90s, more than 90% of CMRs were
used as mixed compounds, then in the last decade, the
demand for individual CMRs and their oxides grew
most intensively. Currently, the share of individual RZ
products is about 30% in volume and more than 70% in
value. At the same time, global demand for SMEs
increased 1.7 times in the 1990s, reaching 79 thousand
tons of SMEs in 2000, while demand for individual rare
earth elements increased from 5 to 9 times during the
same period [9].
Rational analysis of gold and silver
The forms of precious metals in the ore sample were
studied using a rational analysis, which was carried out
according to the standard methodology based on the
sequential leaching of the ground sample (size 85% cl. -
0.074 mm) with a cyanide solution after preliminary
freeing of gold and silver from association with other
ore and rock-forming components. The analysis
scheme included the following operations: sample
cyanidation, alkaline treatment of the I cyanidation
tailings followed by another cyanidation, hydrochloric
acid treatment of the II cyanidation tailings followed by
III cyanidation, nitric acid treatment of the III
cyanidation tailings followed by cyanidation of the
insoluble residue. As can be seen from the data in the
rational analysis, the content of cyanidated free gold in
the tailings sample is 27.87% and silver 32.64%; with
minerals and chemical compounds of antimony and
arsenic, 0.17% of silver is associated; with carbonates,
hydroxides.
iron and manganese are associated with 13.11% gold,
15.16% silver; sulfides (pyrite, arsenopyrite) are
associated with 26.23% gold and 26.54% silver; 32.79%
of gold and 30.49% of silver are found in quartz,
aluminosilicates, and other acid-insoluble minerals.
Currently, cyanide leaching is used to extract gold and
silver from mineral raw materials after beneficiation.
The intensive cyanidation process is based on the use
of high concentrations of cyanide, oxidizer (oxygen),
and alkali [7].
Mineralogical studies of the lying tailings of the MISC
Mineralogical analysis of the initial waste and
processed products was carried out using chemical
atomic absorption, spectral, rational, and test analyses,
based on which a list of minerals from the above-
mentioned samples was compiled.
To determine the material composition of the initial
tailings and processing products, the behavior of gold
and gold-containing sulfides, as well as the main
negative factors affecting tailings enrichment, in
addition to microscopic observation, the following
auxiliary types of research were requiredа. Изучение
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American Journal of Applied Science and Technology (ISSN: 2771-2745)
минерального состава (рудных и нерудных
минералов) продуктов переработки, в том числе:
-
изучение
продуктов
переработки
под
бинокулярным микроскопом (увеличение 16
-56
раз);
- production of polished briquettes;
- study of ore minerals under the "ORTOLUX" ore
microscope at a magnification of 100-1250 times.
Finding gold nuggets using immersion fluids.
b) Conversion of the silicate chemical analysis of waste
processing products into mineral composition, taking
into account all the study materials.
c) Photographing polished briquettes of processed
products with a digital camera (morphology of minerals
and their associations) and obtaining color images.
The content of valuable components and harmful
impurities in the initial sample of MSIM waste is
presented in Table. 7).
Table 4
Content of valuable components in the initial tailings
Sampling Name
Quantity
u.c.
%
Au
Ag
As
Sb
S
com.
Initial tails
0,61
11,61
0,16
0,002
2,04
Mineralogical analysis of initial tailings
Based on the results of mineralogical analysis, ore and
non-ore minerals were identified in the initial sample.
Ore minerals consist mainly of sulfides, which are
replaced by secondary minerals of the oxidation zone,
from partial to complete pseudomorphism. It is also the
most common mineral containing gold. Gold is often
closely related to pyrite as a persistent gold ore, which
cannot be extracted by traditional cyanidation.
Therefore, to extract gold from pyrite, effective
oxidation is necessary. Before leaching, the oxidation of
sulfides can expose the packaged gold, increasing the
contact area of gold with the gold leaching agent and
thus increasing the efficiency of gold leaching [11].
Research on the technological sample for separating
particles from the tailings of the Marjanbulak gold
extraction plant was conducted on the Knelson MD3
concentrator with different rotor rotations, creating
centrifugal force: 50%, 60% and at 60 G (maximum
rotor rotation 2340 rpm). The remaining gravity
regimes (weight of the sample 10 kg, fluidization water
flow rate 2.8-3.0 l/min.) did not change. Three enlarged
laboratory experiments with the above parameters
were set up.
From the research results, it can be seen that with an
increase in rotor speed from 50% to 60G of the
maximum rotor speed, gold extraction in a straight-line
state increases from 35.3% to 50.1%, and silver
extraction decreases from 14.9% to 12.8%. The optimal
rotor rotation, at a grinding rate of 70% -0.074mm for
gold extraction, is 60G. At this rate, a concentrate with
a mass of 764 g (7.64%) was obtained, containing 4
units/l of gold at 50.1% extraction and 19.5 units/l of
silver at 12.8% extraction.
To study the form of gold and silver occurrence, the
concentrate obtained during enrichment in the
concentrator under optimal conditions was subjected
to a rational analysis.
Based on the results of a rational analysis of the
graviocentrate, the distribution of gold and silver by
and the nature of their relationship with ore
components were established:
- free cyanide: gold - 51.37%, silver - 58.48%;
- related to minerals and chemical compounds of
antimony and arsenic: gold - not found, silver - 8.76%;
- associated with carbonates, iron and manganese
hydroxides: gold - 8.23%, silver - 20.62%;
- associated with sulfides (pyrite, arsenopyrite): gold -
35.69%, silver - 9.93%;
- found in quartz, aluminosilicates, and other acid-
insoluble minerals (not extracted): gold - 4.71%, silver -
2.21%.
The technological sample of MSIC tailings belongs to
the mixed (oxidized and sulfide-quartz) type. Valuable
components of tailings are gold and silver.
Characteristic features of gold influencing the
beneficiation technology:
gold's occurrence form is native and in the form of
electrum in goethite (oxidized part). Perhaps isolated
native gold is found in quartz, and in sulfides it is
invisible;
- excretory form - isometric, rounded, oval, elongated,
lens-shaped, etc.;
- by size, gold belongs mainly to finely dispersed and
dust-like classes with a particle size of 0.001-0.05 mm;
- in terms of reflectivity, gold is medium and low-grade.
- no visible gold was found in the initial tail sample.
The main non-metallic minerals are quartz, feldspars,
carbonates, sericites, and chlorites. Accessory minerals
include apatite, rutile+ilmenite, and epidite.
A factor negatively affecting the enrichment of tailings
is the high content of micas - sericite (37%) and clay
substances (7%).
In terms of characteristic properties, quality, as well as
the amount of ore minerals and noble metals in the
waste, processing is significantly inferior to the initial
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American Journal of Applied Science and Technology (ISSN: 2771-2745)
ore, which complicates the waste enrichment process
and predetermines low technological indicators.
According to the results of a rational analysis, the
content of "non-extractable" gold in quartz,
aluminosilicates, and other acid-insoluble minerals in
the initial tailings is 32.79% and bound by sulfides
26.23%.
According to the results of mineralogical analysis, the
frequency of occurrence of native gold in tailings is
significantly higher than in other processed products.
Released gold particles from sulfides, as well as gold
particles bound by non-metallic minerals, undergo a
cupulation process at high temperatures. In this regard,
secondary gold becomes visible and high-quality.
Based on the results of mineralogical studies of MGEP
waste processing products, it is recommended to
conduct oxidative roasting with air supply to detect
"closed" gold in sulfides.
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