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Evalution of the Efficiency of Using an Oxidizer in the Leaching Process of Gold-Containing Concentrate

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28 March 2024

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29 March 2024

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Abstract
The article presents the results of cyanide leaching of gold-containing concentrate using the trichlorocyanuric acid (TCCA) oxidizer. Gold-containing concentrate obtained from a gold tailings sample from a gold recovery factory (GRF) in one of the deposits of Kazakhstan that was not previously studied for concentrability. According to X-ray phase analysis and energy dispersive spectrometry (DSM) data, the main compounds in the tailings sample under study are: pyrite FeS2, quartz SiO2, calcite CaCO3, albite NaAlSi3O8, muscovite KAl2Si3AlO10(OH)8, dolomite CaMg(CO3)2, and oxidized iron compounds. Microscopic studies have established the presence of gold grains in free form, ranging in size from 0.9-10.2 mkm Au-ultrafine and fine gold. Obtaining a gold-containg concentrate with a gold content of 15.95 g / t is possible according to the enrichment scheme, which includes centrifugal separation, classification according to the fineness class -0.05 mm, additional grinding of hydrocyclone sands to a fineness of 90.0-95.0% of the class finer than 0.050 mm, and control centrifugal separation. Since pyrite in technogenic raw materials is the main gold-containing mineral, this paper presents studies on the oxidizability of pyrite with the TCCA oxidizer. The results of studies on the oxidation of pyrite using the TCCA oxidizer show that the products of its hydrolysis oxidize pyrite with the formation of various iron compounds on its surface. Pretreatment of gold-containing concentrate with oxidizer TCCA for 3 hours before the cyanidation process (20 hours) allows to increase the recovery of gold in the solution by 5.8 %.
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Subject: Engineering  -   Mining and Mineral Processing

1. Introduction

Over the past decades, there has been a significant depletion of rich ore reserves. As a result, it became necessary to search for and introduce new methods of producing metals from non-traditional sources of raw materials. Stale tailings of processing plants, dumps of off-balance sheet and substandard ores are a source of expansion of the mineral resource base. In the industrially developed countries of the world, the level of use of industrial waste reaches 70-80 %. For Kazakhstan, which produces a significant share of mineral products and has a strong mining potential, the problem of industrial waste disposal is of paramount importance. The low level of use of man-made raw materials in the republic is explained by the lack of technology and equipment for processing many types of waste. An important circumstance is that the cost of commercial products from industrial waste is usually lower than from ores of mineral deposits extracted by traditional methods. The advantage of man-made dumps is the readiness of the product directly for processing (ores have already been lifted from the subsurface, washed and disintegrated). Another equally important aspect of the “thin gold” problem is that a huge number of man-made dumps accumulated over many decades are becoming profitable due to new technological opportunities and rising gold prices. Therefore, the development of technologies for processing gold-containing technogenic raw materials is an urgent task for the gold mining industry. The progress in improving methods for extracting the useful component allows us to consider man-made dumps as a very attractive source of raw materials [1,2,3]. Man-made dumps can often compete in terms of content and reserves with newly discovered deposits today. Involvement in the processing of these wastes will not only allow obtaining additional products, but also reduce environmental damage to the environment.
In [4], the possibility of obtaining gold and iron concentrate from gold-containing tailings by peforming successive operations: reduction roasting, mechanical activation, leaching, and magnetic separation is shown.
The effect of short-term mechanical activation of gold extraction mill tailings the sulfide flotoability was studied [5,31]. Flotation of finely ground tailings under the optimal reagent regime allowed to increase the recovery of gold in concentrate from 29.0 to 45.4 % with the residual metal content in the waste at the level of 0.2–0.3 g/t.
The article [6] presents the results of tests on the concentrability of gold-containing tailings of the Mazove mine (Zimbabwe) with a gold content of 1.1 g/t. The processing technology includes the processes of flotation, grinding of flotation concentrate to a fineness of less than 25 microns, which ensures the opening of gold and subsequent sorption cyanidation.
Gravity enrichment has become widespread due to its advantages over other methods of processing mineral raw materials, which include its cheapness, environmental safety, separation of minerals without changing their properties, and a wide range of fineness of separated mineral particles. In the practice of processing gold-containing ores, centrifugal separators are widely used, in which the separation of minerals occurs under the action of centrifugal accelerations that are tens and hundreds of times greater than the acceleration of gravity. The use of centrifugal separators made it possible to significantly reduce the size limit of the separated minerals.
Positive results of using centrifugal separators have been obtained in the processing of gold-containing ores from placer and indigenous deposits, current and stale tailings from processing plants, tantalum-niobium, hematite, chromium ores, ilmenite-zircon sands, and coal slurries [7,8,9,10,11,32].
A significant part of the gold in the concentrate is finely interspersed and associated with pyrite and arsenopyrite, which makes it difficult to directly cyanide the enrichment products. Processing of persistent gold-containing raw materials is carried out according to technologies based on the use of pre-oxidative roasting, autoclave and bacterial oxidation, ultrafine grinding with subsequent cyanidation [12,13,14,15,16]. The most common method of opening fine gold associated with pyrite and arsenopyrite and implemented in the practice of processing resistant gold-containing raw materials is oxidative roasting [17,18]. In the pre-oxidation process, a porous structure of mineral complexes is formed, which promotes the penetration of cyanide solutions. Technologies for processing resistant gold-containing ores under the “roasting-cyanidation” scheme are implemented at enterprises in Canada, South Africa, the USA, Australia and other countries [12,31]. The method of oxidative roasting is most widely used in the processing of refractory ores, but it has the main disadvantages: high production costs and serious environmental pollution with a large amount of sulfur and arsenic oxides.
The process of bacterial leaching in relation to gold-containing raw materials is widely used in the world practice and is the most environmentally friendly method of processing compared to other methods.
Biotechnologies can be applied to high arsenic gold-containing concentrates. Bacterial oxidative leaching is an inexpensive and environmentally friendly process for releasing gold from the sulfide matrix. Gold recovery during cyanidation of concentrate ground to a fineness of -30 microns was 55.3% after 48 hours of cyanidation.
The use of pre-biooxidation of gold-containing concentrate for 2 days allowed to dissolve 90% of gold [19]. The disadvantage of the process is the long oxidation cycle, high requirements for the technological equipment used in the leaching process.
The autoclave method of oxidative decomposition of sulfide minerals is known and implemented in the practice of processing persistent gold-containing ores. Water pulp containing sulfides is heated in an autoclave toa temperature of 180-280 °Cat an oxygen pressure exceeding the vapor elasticity of the solution. Gold and silver remain in an insoluble residue from which they can be extracted by cyanidation or other hydrometallurgical methods. The technology of autoclave oxidation -cyanidation makes it possible to extract up to 97% of gold from concentrates [19].
Processing of polymetallic gold-containing concentrates by autoclave oxidation makes it possible to simultaneously extract non-ferrous metals into marketable products. [20,21,22].
The use of oxidative leaching at atmospheric pressure can significantly reduce capital costs in contrast to technologies such as oxidative roasting, autoclave or bacterial leaching. The oxidizer of sulfide minerals is oxygen. Oxygen is supplied using supersonic ejector devices that provide a high rate of mass transfer of oxygen in the reactor. When sulfides are oxidized, a large amount of heat is released, so the operating temperature is close to the boiling point of the pulp (90 - 95 °C). At such operating temperatures, according to theoretical data, leaching occurs in two stages. In the first step, the sulfide mineral (SM) is oxidized to soluble sulfate and elemental sulfur.
There are many studies on the chemical oxidation of gold-containing pyrite and arsenopyrite sulfides using oxidizing agents [2,3].
There is little information in the literature about the use of organic chlorides for opening gold from iron sulfides. Trichlorocyanuric acid (TCCA) is an organic molecule of chlorinated isocyanate with the chemical formula: C3N3O3Cl3
Based on extensive research, trichlorocyanuric acid (TCCA), a cyclic organic chloride containing three chlorines [24-25-25], can make up for the lack of inorganic chlorides. TCCA is hydrolyzed to form HClO, HClO dissociates to form ClO−, Cl2 and O2 are also formed as a result of subsequent reactions, as shown in the equations (2)–(5) [26,27,28,29]. All four types are oxidizing agents, among which HClO is the most active.
C3N3O3CI3 + 3H2O = C3N3O3H3 + 3HCIO
3CIO = 2CI− + CIO3−
2HCIO = 2HCI + O2
5CI−+ CIO3−+ 6H+ = 3CI2 + 3H2O
7CI− +3CIO3− +10H+ = 4CI2 + 2CIO2 + 5H2O
HCIO ↔ H+ + CIO− Kp = 7‧10-9
CI2 + H2O ↔ HCIO + H+ + CI− Kp = 3,94‧10-4
In accordance with equations 6, 7 [2,3], the distribution of the main hydrolysis products from TCCA in an aqueous solution at various pH values was revealed. As can be seen from Figure 1, when the pH value is greater than 7.5, the predominant hydrolysis products are CIO−; when the pH value is from 3.5 to 7.5, the main type is HCIO; and the pH value is less than 3.5,2 Cl2 acts as the main oxidizing agent. Among them, HCIO has the highest redox potential and the strongest oxidizing capacity.
The aim of this work is to develop an effective method for pre-opening gold by oxidizing the sulfide part of the concentrate with trichlorocyanuric acid, followed by cyanidation. Since pyrite in a gold-containing concentrate is the main gold-containing mineral, this paper presents studies on the oxidation of pyrite with trichlorocyanuric acid.

2. Materials and Methods

Our studies were performed to develop technological solutions for the recovery of gold from mature tailings at one of the gold recovery factories (GRF) in Kazakhstan. Mature flotation tailings are a product with a gold content of up to 1.23 g/t. Studies on the oxidation of pyrite using trichloroisocyanuric acid were carried out. Research has been carried out on the oxidation of pyrite using trichloroisocyanuric acid. The following methods were used during our studies:
-
X-ray fluorescent elemental analysis (wave-dispersive combined spectrometer Axios “PANalyical” (Holland);
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X-ray phase analysis (diffractometer “D8-ADVANCE” Bruker Elemental GmbH (Germany);
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Electron microscopic analysis (microprobe analyzer JEOL “JEOLJXA-8230” (Japan);
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Fire assay with AAS finish (NSAM 497-XC method).
-
The spectra of solutions were obtained on an “Avatar IR-Fourier spectrometer 370” in the spectral range 4000-500 cm -1 from capillary layers in KRS-5 windows.
For research, an average sample for studying physical and chemical properties and samples for technological research were selected from the sample of the initial dump tailings. To conduct research, a medium sample was selected from a sample of the original dump tailings to study the physicochemical properties and a sample for technological re-search.
Experiments on gravity enrichment were performed on Knelson KS-MD3 laboratory centrifugal separator (Canada). Technological parameters of raw material enrichment on a centrifugal separator: weight of the suspension – 500 g; size of the initial material - 90-95% of the class -0.05+0 mm, flow rate of diluent water - 4.0 l/min; acceleration of the centrifugal field - 90 m/s2.
Oxidation of pyrite monomineral with a solution of trichloroisocyanuric acid depending on the mixing time and TCCA concentration was carried out according to the functional scheme shown in Figure 2.
The zeta potentials of a pyrite monomineral with a size of -0.050+0 mm before and after interaction with TCCA were determined using Photocor Compact zeta potential and particle size – PhotocorAnalyzer. 1 g of pyrite was added to 50 ml of an aqueous solution with concentrations of 4.3; 8.6; 12.9 and 17.2 mmol / l TCCA. Samples of a 50 ml mineral pulp solution were filtered through a filter paper: yellow tape. To control the pH, a solution with a concentration of 0.05 M NaOH or 0.05 M H2SO4 was used. With constant mixing of the samples for 180 min, the kinetics of the zeta potential change was measured as a function of the TCCA concentration at 20°C.
The ζ-potential of the system was measured at 20°C using Photocor Compact analyzer. The device was equipped with a laser with a wavelength of 657 nm/36 MW, and the measurements were carried out in round vials with an internal diameter of 14.8 mm. The correlation function for each sample was obtained by averaging 10 curves, each of which was obtained over 30 seconds.
The redox potential (ROP) of a -0.050+0 mm pyrite system with different TCCA concentrations was controlled using a combined Pt/Ag-AgCl ROP electrode in an ETHANE pH/ionomer. The ROP kinetics of the samples was measured every 10 minutes for 3 hours at 20°C.
And it is known that due to the formation of different chlorine compounds during the hydrolysis of trichlorocyanuric acids, the oxidation of the process at different pH differs. So, at a pH closer to 1, atomic chlorine is released, which is a strong oxidizer, and at a pH of 5-7, the release of free chlorine is insignificant and requires a long oxidation time. Oxidation was carried out for five hours, until the complete consumption of chlorine a compound (with sampling to determine the potential, sampling time 3; 5 hours), since the remaining chlorine in the pulp will interfere with the process of further cyanide leaching.

3. Results

The material composition of the ore was studied. Studies on the concentrability of gold-containing tailings using a centrifugal separator Knelson were carried out. To determine the phase composition of the flotation tailings sample, X-ray phase analysis (XRP) was performed. According to X-ray phase analysis, the following minerals were determined in the sample: quartz, sericite, chlorite, feldspar, muscovite, and sulfides (Table 1).
The results of X-ray fluorescence analysis of stale GRF tails, shown in Table 2, were obtained using an Axios X-ray fluorescence wave dispersion spectrometer Axios manufactured by Panalytical (Holland). The spectrograms were processed using the Super Q software (Omnian 37).
Analysis of the distribution of gold by size class indicates that the main gold is distributed by size class+0,2; -0,2+0,1; - 0,1+0,07; -0,07+0,05 mm. For example, in the +0.2 mm fineness class, the gold content was 4.0 g / t, with a yield of 9.4 %, up to 30.57% of gold is concentrated in it. In size classes -0,2+0,1; 0,1+0,07; -0,07+0,05 mm gold content is 1.3 g / t, 1.25 g / t and 1.32 g / t, respectively. In the class of -0.05+0 mm, 21.27% of gold is concentrated, while the output is 44.36 % with a content of 0.59 g/t.
The products of sieve analysis of the stale tailings sample were studied on a JEOL electron probe microanalyzer JXA-8230JEOL. Samples of the samples were placed on a double-sided adhesive electrically conductive carbon tape from NISSHIN EM Co. LTD. The results of energy dispersive spectrometry (DPS analysis) “from an area” of the fineness class -0.071+0.05 mm (with an increase of x100) are shown in Figure 3, which allow us to estimate the concentration of elements on the surface. Most of the SEM images were taken in the backscattered electron mode (COMRO), which minimizes resolution degradation and provides better images of such powders compared to the secondary image observation mode (SEI). During the DSP analysis, a beam current of about 10 nA was selected, which corresponds to a sufficient data accumulation rate.
Microscopic studies on the surface (m = 8-10 g, d=25 mm) revealed the presence of free-form gold grains, ranging in size from Au 0.9 –10.2 mkm Au-ultrafine and fine gold (Figure 4). The shape of gold particles is diverse: elongated, isometric, ellipsoid, spongy, spherical, scaly with a developed surface, lamellar with uneven contours. The surface of the particles is both clean, smooth and rough, bumpy.
The presence of oxidized iron compounds in the studied sample of mature tailings of a gold extraction plant indicates that the sulfide minerals (pyrite and chalcopyrite) present in the tailings were oxidized to form iron oxides, hydroxides, sulfates, and carbonates as a result of prolonged exposure to climatic conditions.
Oxidation of pyrite. To find out the possibility of gold-containing pyrite disclosure using an organic chlorine-containing reagent TCCA, depending on the time of the process and on its concentration, we conducted preliminary studies of its interaction with monomineral pyrite. The zeta potential in the shear plane provides important information necessary for analyzing electrostatic interactions between particles, suspension stability, and particle adsorption on mineral surfaces.
To assess the state of the surface of sulfide minerals and the electrostatic component of the interaction forces between particles, the electrokinetic potential was measured. Figure 5 shows the zeta potential of pyrite as a function of pH.
With increasing pH in neutral and alkaline media, pyrite has a negative electrokinetic potential, varying from zero to -25 mV (Figure5). Pyrite has a high negative charge under alkaline conditions and becomes positively charged at pH < 6. With increasing pH values, the absolute value of the zeta potential gradually increased. This is consistent with experimental data in the literature [33].
The histogram (Figure 6) shows the effect of TCCA concentration on the pyrite zeta potential. The concentration of TCCA has a significant effect on the zeta potential. As the concentration of trichloroisocyanuric acid increases in the solution, a large number of iron compound ions are formed and, accordingly, the zeta potential value becomes positive. This means that the reaction of pyrite and trichloroisocyanuric acid produces Fe2+, FeO+, and [Fe(H2O)6]3+ which are adsorbed on the surface of the mineral pyrite. On the other hand, as mentioned above, films consisting of goethite and hematite can form on the surface of pyrite, which also charge the surface of pyrite in a positive charge. However, these films can be dissolved in a solution of one of the products of TCCA hydrolysis, namely in HCI solution by the following reaction (8) and (9):
FeOOH + 3HCI = FeCI3 + 2H2O
Fe2O3 + 6HCI = 2FeCI3 + 3H2O
Figure 7 shows changes in the electrokinetic potential depending on the concentration of the TCCA solution, where it is shown that with an increase in the concentration of TCCA, the value ξ- potential increases in the positive direction. This is due to the oxidation reaction of pyrite with the products of hydrolysis of TCCA, namely hypochlorous acid (HCIO), which is more formed when TCCA is decomposed by water (see reactions 1-5). Consequently, as mentioned above, a large amount of iron (II, III) ions is formed.
Thermodynamic analysis. It is known that when a dry TCCA powder is added to an aqueous solution, the hydrolysis reaction proceeds according to equation (1). Then various chlorine compounds are formed as a result of redox disproportionation reactions (see equations 2-5). As is known 5-7, hypochlorous acid (HClO) is mainly formed at a pH of 5-7 of the medium. Therefore, under the action of TCCA solution with a concentration of 2-2.5 g/l at pH 6 for 3-5 hours, the following reactions can occur without air purging:
FeS2 + 4HCIО = FeSO4 + S + 4HCI        ΔG= −1024.0 kJ
FeS2 +2HCIО = FeCI2 + 2S + H2O + 0.5О2       ΔG = − 371.4 kJ
According to the Gibbs energy value calculated using a computer program, it can be judged that the reaction (10, 11) is mainly taking place. At the same time, hydrochloric acid reacting with iron oxides (hematite,goethite) can form iron (II, III) cations, increasing the ξ - potential in the positive direction, as indicated above.
Measurements were carried out using IR spectroscopy to determine the potential mechanism by which TCCA is adsorbed on mineral surfaces (Figure 8). To investigate the mechanism of TCCA with pyrite, the IR spectra of a pure pyrite sample and a pyrite–TCCA sample were determined to understand the nature of the interaction.
In the TCCA IR spectrum, the absorption peak at 3346 cm−1 was attributed to -OH. The absorption peaks at 1641 and 1323 cm−1 were assigned to the carboxylic carbonyl group, respectively. The absorption peaks at 1623 and 1440 cm−1 were attributed to the aromatic ring with a double bond. Absorption peaks between 1100 and 1000 cm−1 were attributed to C-O deformation. The results of IR spectroscopy are consistent with previous results of TCCA characterization. The spectrum shows automatic correction of the baseline and automatic smoothing in the range of 1000-950 cm-1. The information obtained indicates that TCCA molecules contain a large number of -OH, −CO, which can bind to mineral surfaces and enhance the hydrophilicity of mineral particles. The presence of a band in the spectrum corresponding to the oscillation of the sulfate ion at a wavenumber of 916 cm-1 indicates the coordination of the metal sulfate ion. In the IR spectrum of pyrite, the band at 1085 cm−1 was attributed to the vibration of stretching of single bonds.
To determine which of the above reactions are more likely to occur, we performed thermodynamic calculations using a well-known computer program, which showed the following results: пwhen pyrite is oxidized using HCIO and air oxygen, reactions occur very easily (12,13 and 17,18). These calculated reactions are confirmed by IR spectroscopic data.
2FeS2 + HCIO + 6.5O2 = Fe2O3 + 4SO2 + HCIO3       ΔG = −1560.2 kJ
2FeS2 + HCIO + 6O2 =Fe2O3 + 4SO2+HCIO2        ΔG = −1546.4 kJ
FeS2 + HCIO + 4.5O2 = FeSO4 + SO2 + HCIO4       ΔG = −896.5 kJ
FeS2 + 2HCIO + 5O2 = FeSO4 + S + 2HCIO4       ΔG = −525.1 kJ
FeS2 + 2HCIO + 1.5O2 = FeCI2 + 2SO2 + H2O        ΔG = −829.4 kJ
FeS2 + 4HCIO + 5.5O2 + H2O = FeCI2 + 2H2SO4 + 2HCIO4        ΔG = − 1104.3 kJ
FeS2 + 2HCIO + 6.5O2 + H2O = FeSO4 + H2SO4 + 2HCIO4        ΔG = − 1032.5 kJ
Pyrite oxidation is known as an electrochemical process. The redox potential (ROP) of the solution correlates with the rate of pyrite dissolution (Figure 9). However, pyrite is inert, and an aqueous solution of pyrite has a low ROP of about 100-130 mV. In the oxidation process, it can be detected only at ROP above 200 mV [4]. The redox potential mainly depends on the activity of iron ions, which means that pyrite will oxidize faster if there is a higher percentage of iron ions in the solution.
The redox potential also changes in the same way as the electrokinetic potential changes, which are shown in Figure 10.
With an increase in the concentration of the TCCA solution, the ROP of the system increases accordingly, leading to greater oxidation of pyrite. The optimal oxidation time of pyrite is 60 minutes.
Thus, the results of studies on the oxidation of pyrite using the TCCA oxidizer show that the products of its hydrolysis oxidize pyrite to produce various iron compounds.
Large-scale laboratory tests on the enrichment of initial gold-containing tailings in a centrifugal separator were carried out according to the scheme shown in Figure 11. The first stage of centrifugal separation was carried out at the initial fineness, then the tailings of the 1st centrifugal separation were further ground to a fineness of 90-95 % less than -0.05+0 mm. Centrifugal separation was carried out at a cone rotation speed of 750 min-1 and a turbulizing water flow rate of 6.0 l/min, acceleration of the gravitational fall of 90 °C.
The results of stage enrichment of stale tailings on a centrifugal separator Knelson are presented in Table 3
The results of the experiments show that the enrichment of stale tailings of GRE in a centrifugal separator makes it possible to obtain a combined gold-containing concentrate with a gold content of 15.95 g/t, with a yield of 6.39 %. Gold losses with flotation tailings are 19.28 %.
Obtaining dump tailings with a gold content of 0.264 g/t is possible according to the enrichment scheme, which includes centrifugal separation, classification according to the fineness class -0.05 mm, additional grinding of hydrocyclone sands to a fineness of 90.0-95.0 % of the class finer than -0.05 mm, and control centrifugal separation. The resulting gold-containing concentrate with a gold content of 15.95 g/t is suitable for further processing by hydrometallurgical method.
Cyanidation of the obtained gold-containing concentrate was preceded by pre-oxidation of sulfides using TCCA for 3 hours, at a concentration of 2 g/l. The results of leaching the gold-containing concentrate are shown in Figure 12 as a function of the cyanidation time.
From the results obtained, it follows that pretreatment of gold-containing concentrate with an oxidizer TCCA for 3 hours before the cyanidation process (20 hours). allows to increase the recovery of gold in the solution by 5.8 %.
In this paper, the oxidation of pyrite in TCCA solution is studied by the redox potential and zeta potential and thermodynamic analysis of the reactions. The results of studies on the oxidation of pyrite using the TCCA oxidizer show that the products of its hydrolysis oxidize pyrite toproduce various iron compounds and thereby contribute to the intensification of the cyanidation process of gold-containing concentrate.
Sulfate ions in solution were analyzed by complex titration. 1 gram of monomineral was mixed with TCCA (17.2 mmol/l), and then aliquot was taken and titrated with EDTA. The amount of sulfate ion was 3.22 mmol/l at the initial TCCA. After interaction with monomineral, its amount increased by 16.12 mmol/l. That is, the presence of 12.90 mmol/l sulfate ions in the total solution is explained by the oxidation of the monomineral surface.

4. Discussion

The conclusions of this study are as follows:
- chemical oxidation of pyrite occurs mainly in an acidic and slightly alkaline environment. Pyrite has a high negative charge under alkaline conditions and becomes positively charged at pH< 6. With an increase in pH in neutral and alkaline media, pyrite has a negative electrokinetic potential, varying from zero to -25 mV.
- the results of studies on the oxidation of pyrite using the TCCA oxidizer show that the products of its hydrolysis oxidize pyrite with the formation of various iron compounds on its surface.
- the results of the experiments show that the enrichment of stale tailings of GRF in a centrifugal separator allows you to get a combined gold-containing concentrate with a gold content of 15.95.g/t, with a yield of 6.39.%, which, not being conditioned, allows you to cyanide a relatively small mass of it, which as a result reduces the operating costs for processing gold-containing concentrate. Gold recovery in Knelson’s concentrate was 80.72 %.
- it was found that pretreatment of gold-containing concentrate with TCCA and subsequent leaching in cyanide solutions can increase the recovery of gold in solution by 5.8%

Author Contributions

Conceptualization, B.K., N.K. and G.Zh..; methodology, G.Zh. and N.O.; software, N.O.; validation, A.K., D.Ye., Zh.A.; formal analysis, N.K. and G.Zh.; investigation, D.Ye. and A.K.; resources, N.K.; data curation, N.O., Zh.A.; writing—original draft preparation, N.K. and G.Zh.; writing—review and editing, N.K. and N.O.; visualization, D.Ye., Zh.A.; supervision, B.K.; project administration, B.K.; funding acquisition, B.K. All authors have read and agreed to the published version of the manuscript.

Funding

This research has been funded by the Committee of Science of the Ministry of Science and Higher Education of the Republic of Kazakhstan (Grant No. BR21882140).

Data Availability Statement

Some or all of the data or code supporting the results of this study are available from the corresponding authors upon request.

Conflicts of Interest

The authors declare no conflicts of interest.

References

  1. Master plan for the development of the mining and metallurgical industry of the Republic of Kazakhstan until 2030. Available online: https://kapital.kz/economic/4765/v-rk-razrabotayut-master-plan-razvitiya-gorno-metallurgicheskogo-kompleksa.html. (accessed on 4 December 2023).
  2. Kenzhaliyev, B.; Surkova, T.; Yessimova, D.; Baltabekova, Zh.; Abikak, Y.; Abdikerim, B.; Dosymbayeva, Z. Extraction of noble metals from pyrite cinders. Chemengineering 2023, 7, 14. [Google Scholar] [CrossRef]
  3. Toktar, G.; Magomedov, D.R.; Кoizhanova, A.K.; Abdyldaev, N.N.; Bakraeva, A.N. Extraction of gold from low-sulfide gold-containing ores by beneficiating method using a pressure generator for pulp microaeration. Kompleksnoe Ispolʹzovanie Mineralʹnogo syrʹâ/Complex Use of Mineral Resources/Mineraldik Shikisattardy Keshendi Paidalanu, 2023; 325. [Google Scholar] [CrossRef]
  4. Lei Zhang; Tao Jiang; Xue-Yi Guo; Qing-Hua Tian; Shui-Ping Zhong; Li Dong; Hong Qin; Zuo-Wei Liu; Brian Makuza. Sustainable processing of gold cyanide tailings: Reduction roasting, mechanical activation, non-cyanide leaching, and magnetic separation. Hydrometallurgy 2023, 217. [Google Scholar] [CrossRef]
  5. Bragin, V.I.; Burdakova E.A.; Kondrateva, A.A.; Plotnikova, A.А.; Baksheeva. Dressability of old gold-containing tailings by flotation. Journal of mining science 2019, 54, 663-670. [CrossRef]
  6. Bantshi, A.M; Makuvise, P. Extraction of gold from sands and slimes tailings dump from Mazowe mine, Zimbabwe. Proceedings of the 3rd Pan American Materials Congress 2017, 507–517. [Google Scholar] [CrossRef]
  7. Guney, A.; Önal, G.; Atmaca, T. New aspect of chromite gravity tailings re-processing. Miner. Eng. 2001, 14, 1527–1530. [Google Scholar] [CrossRef]
  8. Sen, S. Gold recovery by KC from grinding circuit of Bergama CIP plant. Rem Rev. Esc. Minas 2010, 63, 539–545. [Google Scholar] [CrossRef]
  9. Uslu, T.; Sahinoglu, E.; Yavuz, M. Desulphurization and deashing of oxidized fine coal by Knelson concentrator. Fuel Process. Technol. 2012, 101, 94–100. [Google Scholar] [CrossRef]
  10. Kökkılıç, O.; Langlois, R.; Waters, K.E. A design of experiments investigation into dry separation using a Knelson concentrator. Miner. Eng. 2015, 72, 73–86. [Google Scholar] [CrossRef]
  11. Abbruzzese, S.; Ubaldini, F.; Veglio, L.; Toro. Preparatory bioleaching to the conventional cyanidation of arsenical gold ores. Miner. Eng. 1994, 7, 49-60.
  12. Lodeyshchikov, V.V. Technology for extracting gold and silver from refractory ores; Publisher: OJSC “Irgiredmet”, Irkutsk, 1999; pp. 452.
  13. Abdul Hapid; Siti Zullaikah; Mahfud; Adji Kawigraha; Yanto Sudiyanto; Ratika Benita Nareswari; Armando T. Quitain. Oxidation of sulfide mineral and metal extraction analysis in the microwave-assisted roasting pretreatment of refractory gold ore. Arabian Journal of Chemistry 2024, 17. [CrossRef]
  14. Watling, H. Microbiological Advances in Biohydrometallurgy. Minerals 2016, 6, 49. [Google Scholar] [CrossRef]
  15. Fomchenko, N.V.; Muravyov, M.I.; Kondrateva, T.F. Two-stage bacterial–chemical oxidation of refractory gold-containing sulfidic concentrates. Hydrometallurgy 2010, 101, 28–34. [Google Scholar] [CrossRef]
  16. Koizhanova, A.K.; Toktar, G.; Banks Craig, E.; Magomedov, D.R.; Kubaizhanov, A.A. Research of hydrometallurgical method of leaching gold from flotation tails with using bio-oxidation. Kompleksnoe Ispolʹzovanie Mineralʹnogo syrʹâ/Complex Use of Mineral Resources/Mineraldik Shikisattardy Keshendi Paidalanu 2020, 314, 28–39. [Google Scholar] [CrossRef]
  17. Amaya, D.; Bernal, S.; Garnica, M.; Reslen, R. Correa. Improved roasting of some colombian gold ores. Revista Dyna 2013, 80, 70–77. [Google Scholar]
  18. Karimova, L.M.; Oleinikova, T.O.; Mansurov, B.E.; Saganbek, S. Oxidizing roasting and cyanidation for the processing of refractory gold concentrates. Obogashchenie Rud 2023, 3, 10–15. [Google Scholar] [CrossRef]
  19. Abbruzzese, S.; Ubaldini, F.; Veglio, L.; Toro. Preparatory bioleaching to the conventional cyanidation of arsenical gold ores. Min. Eng. 1994, 7, 49-60. [CrossRef]
  20. María, M. Salazar-Campoy; Jesus Leobardo Valenzuela; Luis S. Quiróz-Castillo; Martín A. Encinas-Romero. Gold extraction from a refractory sulfide concentrate by simultaneous pressure leaching/oxidation. Minerals 2023, 13, 116. [Google Scholar] [CrossRef]
  21. Adewuyi, S.O.; Ahmed, H.A.M.; Ahmed, H.M.A. Methods of ore pretreatment for comminution energy reduction. Minerals 2020, 10. [Google Scholar] [CrossRef]
  22. Alejandro Valenzuela; Jesús L. Valenzuela; José R. Parga. Effect of pretreatment of sulfide refractory concentrate with sodium hypochlorite, followed by extraction of gold by pressure cyanidation, on gold removal. Advances in Chemical Engineering and Science 2013, 3, 7. [CrossRef]
  23. Feng, F.; Sun, Y.X.; Rui, J.Y.; Yu, L.; Liu, J.M.; Zhang, N.; Zhao, M.X.; Wei, L.W.; Lu, C.S.; Zhao, J.; Zhang, Q.F.; Li, X.N. Study of the “Oxidation-complexation” coordination composite ionic liquid system for dissolving precious metals. Appl. Sci. 2020, 10, 3625. [Google Scholar] [CrossRef]
  24. Puvvada, G.V.K.; Murthy, D.S.R. Selective precious metals leaching from a chalcopyrite concentrate using chloride/hypochlorite media. Hydrometallurgy 2000, 58, 185–191. [Google Scholar] [CrossRef]
  25. Basu, N.; Maity, S.K.; Chaudhury, A.; Ghosh, R. Trichloroisocyanuric acid (TCCA):an efficient green reagent for activation of thioglycosides toward hydrolysis. Carbohydr. Res. 2013, 369, 10–13. [Google Scholar] [CrossRef] [PubMed]
  26. Samusev, A.L.; Tomskaya, E.S. Modern methods for intensifying the process of leaching gold from refractory mineral raw materials. Mining Information and Analytical Bulletin 2015, 8, 100–105. [Google Scholar]
  27. Teut, A.O.; Kuimov, D.V.; Kosyanov, E.A. Extraction of gold from refractory sulfide ores using the electrochlorination method. New technologies for enrichment and complex processing of difficult-to-enrich natural and technogenic mineral raw materials, 2011; 513–516. [Google Scholar]
  28. Li, S.K.; Gu, G.H.; Qiu, G.Z.; Chen, Z.X. Flotation and electrochemical behaviors of chalcopyrite and pyrite in the presence of N-propyl-N0—Ethoxycarbonyl thiourea. Trans. Nonferrous Metals Soc. China. 2018, 28, 1241–1247, http://www.ysxbcn.com/down/2018/06_en/20-p1241.pdf. [Google Scholar] [CrossRef]
  29. Feng, B.; Feng, Q.; Lu, Y. The effect of lizardite surface characteristics on pyrite flotation. App. Surf. Sci. 2012, 259, 153–158. [Google Scholar] [CrossRef]
  30. Bicak, O.; Ekmekci, Z.; Bradshaw, D.J.; Harris, P.J. Adsorption of guar gum and CMC on pyrite. Miner. Eng. 2007, 20, 996–1002. [Google Scholar] [CrossRef]
  31. Chang, C.S.; Yusoff, A.H.; Mohamed, C.A.R.; Liu, S.F.; Shoparwe, N.F.; Husain, N.A.; Azlan, M.N. Geochemistry of Rare Earth Elements in Pahang River Sediment, Malaysia. Kompleksnoe Ispolʹzovanie Mineralʹnogo syrʹâ/Complex Use of Mineral Resources/Mineraldik Shikisattardy Keshendi Paidalanu 2024, 331, 42–50. [Google Scholar] [CrossRef]
  32. Kenzhaliyev, B.K. Innovative Technologies Providing Enhancement of Non-Ferrous, Precious, Rare and Rare Earth Metals Extraction. Kompleksnoe Ispolʹzovanie Mineralʹnogo syrʹâ/Complex Use of Mineral Resources/Mineraldik Shikisattardy Keshendi Paidalanu 2019, 310, 64–75. [Google Scholar] [CrossRef]
  33. Cheng, W.; Deng, Z.; Tong, X.; Lu, T. Hydrophobic Agglomeration of Fine Pyrite Particles Induced by Flotation Reagents. Minerals 2020, 10, 1–16. [Google Scholar] [CrossRef]
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Figure 1. Distribution of the main types of hydrolysis products from TCCA at different pH values.
Figure 1. Distribution of the main types of hydrolysis products from TCCA at different pH values.
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Figure 2. Measurement of the zeta potential and redox potential.
Figure 2. Measurement of the zeta potential and redox potential.
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Figure 3. Results of DSP-analysis of pyrite.
Figure 3. Results of DSP-analysis of pyrite.
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Figure 4. Free gold particles in polystyrene.
Figure 4. Free gold particles in polystyrene.
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Figure 5. ζ-potential of pyrite as a function of pH.
Figure 5. ζ-potential of pyrite as a function of pH.
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Figure 6. Influence of TCCA concentration on the zeta potential of pyrite.
Figure 6. Influence of TCCA concentration on the zeta potential of pyrite.
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Figure 7. Kinetics of zeta potential change as a function of TCCA concentration.
Figure 7. Kinetics of zeta potential change as a function of TCCA concentration.
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Figure 8. IR spectra of pyrite before and after TCCA treatment.
Figure 8. IR spectra of pyrite before and after TCCA treatment.
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Figure 9. Effect of TCCA concentration on the redox potential of pyrite.
Figure 9. Effect of TCCA concentration on the redox potential of pyrite.
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Figure 10. Kinetics of changes in ROP as a function of TCCA concentration.
Figure 10. Kinetics of changes in ROP as a function of TCCA concentration.
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Figure 11. Scheme of enrichment of stale mill tailings using a centrifugal separator.
Figure 11. Scheme of enrichment of stale mill tailings using a centrifugal separator.
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Figure 12. Dependence of gold extraction into solution on cyanidation time.
Figure 12. Dependence of gold extraction into solution on cyanidation time.
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Table 1. X-ray phase analysis of the initial ore.
Table 1. X-ray phase analysis of the initial ore.
Compound Name Formula S-Q
Quartz, syn SiO2 54.7
Calcite, magnesian (Mg0.064Ca0.936)(CO3) 12
Clinochlore 1MIa Mg2.5Fe1.65Al1.5Si2.2Al1.8O10(OH)8 11.2
Dolomite CaMg(CO3)2 6.3
Albite Na(AlSi3O8) 5
Riebeckite Na2Fe3Fe2Si8O22(OH)2 4.8
Pyrite FeS2 3.4
Muscovite 2M1, syn KAl2Si3AlO10(OH)2 2.7
Table 2. Results of the X-ray fluorescence analysis of gold recovery plant tailings.
Table 2. Results of the X-ray fluorescence analysis of gold recovery plant tailings.
Chemical Element Content, % Chemical Element Content, %
O 37.195 Cr 0.037
Na 0.976 Mn 0.091
Mg 2.131 Fe 5.293
Al 7.022 Co 0.013
Si 23.273 Ni 0.013
P 0.055 Cu 0.004
S 0.257 Zn 0.013
Cl 0.064 Sr 0.014
K 0.993 Zr 0.005
Ca 3.908 Pb 0.018
Ti 0.355
Table 3. Results of stage enrichment of stale tailings in a centrifugal separator.
Table 3. Results of stage enrichment of stale tailings in a centrifugal separator.
Products Yield, % Gold content, g/t Gold recovery, %
I centrifugal separator concentrates 3.22 17.1 43.33
II centrifugal separation concentrate 3.19 14.8 37.39
combined ash concentrate 6.41 15.95 80.72
Centrifugal separator tailings 93.61 0.26 19.28
Initial tailings 100.0 1.263 100.0
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