Glycine and sodium thiosulfate based gold leaching reagent systems and heap leaching of gold bearing mineral materials

Abstract

This application provides a gold leaching reagent system based on glycine and sodium thiosulfate, and a heap leaching process for gold-bearing minerals, belonging to the field of hydrometallurgical technology. The gold leaching reagent system includes: a mixed ligand gold leaching agent, a synergistic catalyst, and a sodium thiosulfate stabilizer; wherein the mixed ligand gold leaching agent includes glycine and sodium thiosulfate, the synergistic catalyst includes glutamic acid and molybdenum disulfide, and the sodium thiosulfate stabilizer is polyvinyl ammonium phosphate; the mass concentration of glycine is 10-50 g / L, the mass concentration of sodium thiosulfate is 10-15 g / L, the mass concentration of glutamic acid is 1-4 g / L, the mass concentration of molybdenum disulfide is 0.2-0.3 g / L, and the mass concentration of polyvinyl ammonium phosphate is 0.1-0.5 g / L. This application achieves efficient extraction of encapsulated gold under mild alkaline conditions, with low sodium thiosulfate consumption, high gold leaching rate, and is environmentally friendly and economical, suitable for heap leaching of low-grade gold-bearing sulfide ores.

Description

Technical Field

[0001] This application relates to the field of hydrometallurgical technology, specifically to a gold leaching reagent system based on glycine and sodium thiosulfate and a heap leaching process for gold-bearing mineral materials. Background Technology

[0002] Thiosulfate leaching is considered one of the most promising gold leaching technologies to replace cyanidation due to its advantages such as non-toxicity, rapid leaching rate, and good adaptability to refractory gold ores. However, traditional thiosulfate leaching systems face two major bottlenecks in practical applications: First, sodium thiosulfate is easily oxidized and decomposed into ineffective products such as sulfates and polythionates by dissolved oxygen during leaching, resulting in high reagent consumption and unstable leaching rates. Second, for low-grade gold ores encapsulated by sulfide minerals such as pyrite and pyrrhotite, thiosulfate solutions are unable to effectively disrupt the dense structure of sulfide minerals, leaving gold particles firmly encapsulated in the mineral matrix and unable to contact the leaching agent, leading to low gold leaching rates. Existing improvement schemes mostly focus on adding a copper-ammonia catalytic system to accelerate gold oxidation, or using pretreatment methods such as mechanical grinding and oxidative roasting to open the encapsulation. However, these methods either introduce toxic substances or are energy-intensive, making it difficult to meet the requirements of green, economical, and low-grade heap leaching treatment.

[0003] Although there are existing technologies for amino acid-assisted thiosulfate leaching of gold, they are mostly limited to the coordination effect of glycine alone, and there is no multi-level synergistic system that simultaneously takes into account thiosulfate stabilization, catalytic pre-oxidation of sulfide ores and iron ion chelation pore formation.

[0004] Therefore, designing a reagent system that can simultaneously inhibit the degradation of sodium thiosulfate and selectively etch sulfide minerals, thereby exposing and dissolving encapsulated gold in situ, has become a pressing technical challenge in this field. Summary of the Invention

[0005] In view of the technical problems existing in the background art, this application provides a gold leaching agent system based on glycine and sodium thiosulfate and a heap leaching process for gold-bearing minerals. This gold leaching agent system based on glycine and sodium thiosulfate is a multi-stage synergistic agent system that stabilizes sodium thiosulfate with polyvinyl alcohol ammonium phosphate, pre-oxidizes sulfide minerals with molybdenum disulfide, chemically creates pores by chelating iron ions with glutamic acid, and synergistically leaches gold with glycine and sodium thiosulfate. It achieves efficient heap leaching treatment of low-grade gold ores encapsulated in pyrite and pyrrhotite under mild alkaline conditions, and solves the two core technical problems of easy degradation of thiosulfate and difficulty in contacting the leaching agent with encapsulated gold in traditional processes.

[0006] To achieve the above objectives, in a first aspect, embodiments of this application provide a gold leaching agent system based on glycine and sodium thiosulfate, comprising: a mixed ligand gold leaching agent, a synergistic catalyst, and a sodium thiosulfate stabilizer; wherein, The mixed ligand immersion gold agent includes glycine and sodium thiosulfate, the co-catalyst includes glutamic acid and molybdenum disulfide, and the sodium thiosulfate stabilizer is polyvinyl ammonium phosphate. The mass concentrations of glycine, sodium thiosulfate, glutamic acid, molybdenum disulfide, and polyvinyl ammonium phosphate are 10-50 g / L, 10-15 g / L, 1-4 g / L, 0.2-0.3 g / L, and 0.1-0.5 g / L, respectively.

[0007] Furthermore, the mass ratio of glycine to sodium thiosulfate is (1-5):1.

[0008] Furthermore, the mass ratio of glutamic acid to molybdenum disulfide is (5-20):1.

[0009] Furthermore, the pH range for the use of the gold immersion reagent system is 8.0-10.0.

[0010] Secondly, embodiments of this application provide a heap leaching process for gold-bearing minerals, employing the aforementioned gold leaching agent system based on glycine and sodium thiosulfate, comprising the following steps: After crushing the gold-bearing mineral material, it was added to the heap leaching column; A gold leaching agent system based on glycine and sodium thiosulfate was added to the upper part of the heap leaching column. The column was circulated and leached under a pH of 8.0-10.0 environment. The leachate flowing out from the lower part was collected to obtain a gold-containing solution and mineral tailings. The gold leaching rate was calculated by fire assay on the tailings of the leached minerals, as shown in equation (I): Formula (I): where η1 represents the gold leaching rate by slag, in %; m1 represents the mass of the original leached sample, in g; β1 represents the grade of the original leached sample, in g / t; m2 represents the mass of the residue after leaching, in g; β2 represents the grade of the residue after leaching, in g / t. The concentration of gold in the gold-containing precious liquid was determined by inductively coupled plasma atomic emission spectrometry (ICP-AES), and the liquid-phase leaching rate of gold was calculated as shown in equation (II). ; Formula (II): where η2 represents the liquid phase leaching rate of gold, in %; m1 represents the mass of the original leaching sample, in g; β1 represents the grade of the original leaching sample, in g / t; C represents the concentration of gold in the gold-containing precious solution, in mg / L; and V represents the volume of the gold-containing precious solution, in L.

[0011] Furthermore, the crushing of gold-bearing mineral materials includes crushing the gold-bearing mineral materials to a particle size of ≤5cm, where the mineral particles account for 75%-85% of the total mass of the gold-bearing mineral materials.

[0012] Furthermore, the rinsing injection flow rate is 12-14 L / (m²). 2 ·h); and / or, The cyclic rinsing is carried out at normal temperature and pressure.

[0013] Furthermore, the rinsing cycle is 40-45 days.

[0014] Furthermore, data is considered valid if the deviation between the gold slag leaching rate and the gold liquid phase leaching rate is ≤1%.

[0015] Furthermore, the gold-bearing mineral materials include one or more of the following: oxidized heap leaching residue, gold-bearing roasted sand with a gold content of 1-10 g / t, and gold ore with a gold grade of 0.5-1.5 g / t.

[0016] The beneficial technical effects of this application are as follows: The multi-stage synergistic reagent system constructed in this application—polyvinyl alcohol ammonium phosphate stabilizing sodium thiosulfate—molybdenum disulfide catalyzing pre-oxidation of sulfide ores—glutamic acid chelating iron ions for chemical pore formation—glycine and sodium thiosulfate synergistic gold leaching—exhibits significant technical advantages in heap leaching of low-grade gold-bearing sulfide ores containing pyrite and pyrrhotite. The introduction of polyvinyl alcohol ammonium phosphate significantly reduces the decomposition rate of sodium thiosulfate during the leaching cycle, resulting in a significant reduction in reagent consumption. The combined action of molybdenum disulfide nanocatalyst and glutamic acid can etch dense nanoscale chemical channels on the surface of pyrite and pyrrhotite in a short time, fully exposing the gold particles that were originally densely encapsulated by sulfide minerals. Based on this, the mixed ligand gold leaching system of glycine and sodium thiosulfate achieves simultaneous dissolution of the exposed gold, significantly increasing the total gold leaching rate compared to the single sodium thiosulfate process, while completely avoiding the use of cyanide, thus significantly improving environmental safety.

[0017] The technical solution of this application achieves efficient extraction of gold encapsulated in low-grade sulfide ores under mild alkaline conditions, eliminating the need for energy-intensive pretreatment processes such as high-pressure oxidation and high-temperature roasting, thus significantly reducing equipment investment and operating energy consumption. Due to the synergistic effect of glutamic acid's strong chelating effect on iron ions and polyvinyl alcohol ammonium phosphate's inhibitory effect on the passivation layer on the gold surface, the amount of secondary precipitation of iron ions on the mineral surface during leaching is significantly reduced, effectively avoiding re-passivation of the gold surface. This results in a significantly shortened heap leaching cycle, stable gold complex concentration in the leachate, and extremely low gold residue in the tailings. This achieves efficient and economical development and utilization of low-grade gold-bearing sulfide ore resources, providing an easily industrialized technical solution for the green heap leaching of low-grade, difficult-to-process gold ores.

[0018] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of this application, the accompanying drawings used in this application will be briefly described below. Obviously, the drawings described below are merely some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without any creative effort.

[0020] Figure 1 The injection flow rate is 13 L / (m³). 2 ·h) The overall concentration evolution process of the 10m thick heap leaching model over time.

[0021] Figure 2 This is a scanning electron microscope image of gold encapsulated in pyrite in the raw ore.

[0022] Figure 3 This is a scanning electron microscope image of the gold-bearing mineral material in Example 1 three days after dissolution. Detailed Implementation

[0023] The embodiments of the technical solution of this application will now be described in detail with reference to the accompanying drawings. These embodiments are only used to more clearly illustrate the technical solution of this application and are therefore merely examples, and should not be used to limit the scope of protection of this application.

[0024] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0025] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0026] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is expected that ranges of 60-110 and 80-120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this article; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0027] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0028] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0029] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0030] Unless otherwise specified, the terms "comprising" and "including" as used in this application are open-ended. For example, "comprising" and "including" may mean that other components not listed may also be included or contained.

[0031] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0032] The embodiments of this application will be described in further detail below with reference to the accompanying drawings and examples. The detailed description of the following embodiments and the accompanying drawings are used to illustrate the principles of this application by way of example, but should not be used to limit the scope of this application, that is, this application is not limited to the described embodiments.

[0033] Thiosulfate leaching is considered one of the most promising gold leaching technologies to replace cyanidation due to its advantages such as non-toxicity, rapid leaching rate, and good adaptability to refractory gold ores. However, traditional thiosulfate leaching systems face two major bottlenecks in practical applications: First, sodium thiosulfate is easily oxidized and decomposed into ineffective products such as sulfates and polythionates by dissolved oxygen during leaching, resulting in high reagent consumption and unstable leaching rates. Second, for low-grade gold ores encapsulated by sulfide minerals such as pyrite and pyrrhotite, thiosulfate solutions are unable to effectively disrupt the dense structure of sulfide minerals, leaving gold particles firmly encapsulated in the mineral matrix and unable to contact the leaching agent, leading to low gold leaching rates. Existing improvement schemes mostly focus on adding a copper-ammonia catalytic system to accelerate gold oxidation, or using pretreatment methods such as mechanical grinding and oxidative roasting to open the encapsulation. However, these methods either introduce toxic substances or are energy-intensive, making it difficult to meet the requirements of green, economical, and low-grade heap leaching treatment.

[0034] Although there are existing technologies for amino acid-assisted thiosulfate leaching of gold, they are mostly limited to the coordination effect of glycine alone, and there is no multi-level synergistic system that simultaneously takes into account thiosulfate stabilization, catalytic pre-oxidation of sulfide ores and iron ion chelation pore formation.

[0035] Therefore, designing a reagent system that can simultaneously inhibit the degradation of sodium thiosulfate and selectively etch sulfide minerals, thereby exposing and dissolving encapsulated gold in situ, has become a pressing technical challenge in this field.

[0036] To address the aforementioned technical problems, in a first aspect, embodiments of this application provide a gold leaching agent system based on glycine and sodium thiosulfate, comprising: a mixed ligand gold leaching agent, a synergistic catalyst, and a sodium thiosulfate stabilizer; wherein, The mixed ligand immersion gold agent includes glycine and sodium thiosulfate, the co-catalyst includes glutamic acid and molybdenum disulfide, and the sodium thiosulfate stabilizer is polyvinyl ammonium phosphate. The mass concentrations of glycine, sodium thiosulfate, glutamic acid, molybdenum disulfide, and polyvinyl ammonium phosphate are 10-50 g / L, 10-15 g / L, 1-4 g / L, 0.2-0.3 g / L, and 0.1-0.5 g / L, respectively.

[0037] It can be explained that this application introduces polyvinyl ammonium phosphate as a stability regulator for sodium thiosulfate. The organic ammonium salt cation in its molecular structure works synergistically with the phosphate group to form a dynamic weak interaction shielding layer around the thiosulfate ion, effectively blocking the direct oxidative attack of dissolved oxygen on thiosulfate and inhibiting its decomposition pathway to ineffective products such as sulfate and tetrathiosulfate. This maintains the sodium thiosulfate in the system at a stable supply kinetic platform, overcoming the problems of leaching rate fluctuations and excessive reagent consumption caused by the rapid degradation of sodium thiosulfate in traditional processes.

[0038] It can be explained that by introducing molybdenum disulfide solid nanocatalyst as a pre-oxidation promoter for sulfide minerals, the molybdenum active sites in its layered structure catalyze the breaking of Fe-S bonds in pyrite / pyrrhotite through interfacial electron transfer, inducing lattice instability and gradual disintegration of sulfide minerals.

[0039] It can be explained that, through the synergistic effect of glutamic acid and molybdenum disulfide, glutamic acid, through its dicarboxyl structure, strongly chelates and attacks the dissolved iron ions, continuously extracting iron from the mineral framework. This etches nano- to micron-scale chemical channels into the sulfide mineral, completely exposing the gold particles originally encapsulated by the sulfide mineral. Glycine and sodium thiosulfate are the core components of the mixed ligand leaching agent. Under stabilization conditions, sodium thiosulfate catalyzes the oxidation of elemental gold to generate monovalent gold ions (Au). + This ion reacts simultaneously with thiosulfate (S2O3). 2- The gold and glycine anions compete for coordination, forming a more thermodynamically stable gold-amino acid complex, driving a continuous rightward shift in the gold dissolution equilibrium. During this process, polyvinyl phosphate (PVP) effectively prevents gold surface passivation, further improving the leaching rate.

[0040] In some embodiments, the mass ratio of glycine to sodium thiosulfate is (1-5):1.

[0041] In this embodiment, the mass ratio of glycine to sodium thiosulfate is controlled at (1-5):1. Glycine, as the primary ligand for gold, reduces the amount of sodium thiosulfate required. After pre-oxidation of molybdenum disulfide sulfide ore and chemical pore-forming by glutamic acid chelation of iron ions, gold is fully exposed and exists in an oxidized state. Due to its small molecular size and rapid diffusion, glycine can quickly form a stable chelate with gold ions, increasing the gold leaching rate. Upon addition of thiosulfate ions, ligand exchange occurs with the glycine-gold chelate, forming a mixed ligand complex. Because thiosulfate has higher thermodynamic stability, it can further fix the gold chelated by glycine into a stable complex, reducing gold reduction or re-adsorption.

[0042] In some embodiments, the mass ratio of glutamic acid to molybdenum disulfide is (5-20):1.

[0043] In this embodiment, the mass ratio of glutamic acid to molybdenum disulfide is controlled at (5-20):1. Glutamic acid dissolves iron minerals in ore fissures through chelation, thereby etching out channels and exposing the gold encapsulated by sulfides. Additionally, it can form a coating on the surface of molybdenum disulfide, regulating its catalytic activity. At this ratio, sufficient glutamic acid molecules densely attack ore defects and grain boundaries, forming a widely interconnected microfissure network, increasing the exposure of the encapsulated gold and facilitating subsequent gold leaching efficiency.

[0044] In some embodiments, the pH of the environment in which the gold immersion agent system is used is 8.0-10.0.

[0045] In this embodiment, glycine is an amphoteric electrolyte, and its amino group's coordination ability with gold ions increases with increasing pH. Within the pH range of 8.0-10.0, glycine mainly exists as a glycinate anion, with its amino nitrogen atom's lone pair electrons fully exposed, enabling it to rapidly form a stable gold-glycine chelate with gold ions. A pH of 8.0-10.0 allows the thiosulfate ion to maintain an effective concentration over a long period, acting as a secondary ligand to stabilize the gold complex. This pH range ensures that both ligands are simultaneously active, synergistically enhancing the gold leaching efficiency. Within the pH range of 8.0-10.0, glutamic acid's carboxyl group fully dissociates, enhancing its ability to chelate iron ions. This allows it to continuously dissolve gangue minerals or oxidation products, expanding the gold leaching channels while reducing iron hydroxide precipitation to prevent pore blockage. Under weakly alkaline conditions, the efficiency of molybdenum disulfide catalyzing the generation of ·OH radicals remains stable, with mild and controllable oxidation intensity, stripping away the sulfides encapsulating the gold and maintaining an environment conducive to gold leaching after pore formation.

[0046] Secondly, embodiments of this application provide a heap leaching process for gold-bearing minerals, employing the aforementioned gold leaching agent system based on glycine and sodium thiosulfate, comprising the following steps: After crushing the gold-bearing mineral material, it was added to the heap leaching column; A gold leaching agent system based on glycine and sodium thiosulfate was added to the upper part of the heap leaching column. The column was circulated and leached under a pH of 8.0-10.0 environment. The leachate flowing out from the lower part was collected to obtain a gold-containing solution and mineral tailings. The gold leaching rate was calculated by fire assay on the tailings of the leached minerals, as shown in equation (I): Formula (I): where η1 represents the gold leaching rate by slag, in %; m1 represents the mass of the original leached sample, in g; β1 represents the grade of the original leached sample, in g / t; m2 represents the mass of the residue after leaching, in g; β2 represents the grade of the residue after leaching, in g / t. The concentration of gold in the gold-containing precious liquid was determined by inductively coupled plasma atomic emission spectrometry (ICP-AES), and the liquid-phase leaching rate of gold was calculated as shown in equation (II). ; Formula (II): where η2 represents the liquid phase leaching rate of gold, in %; m1 represents the mass of the original leaching sample, in g; β1 represents the grade of the original leaching sample, in g / t; C represents the concentration of gold in the gold-containing precious solution, in mg / L; and V represents the volume of the gold-containing precious solution, in L.

[0047] It can be noted that the leaching tailings were tested using the fire assay method, and the analytical method was performed according to the fire assay method specified in GB / T7739.1-2019 "Chemical Analysis Methods for Gold Concentrates Part 1: Determination of Gold and Silver Contents". The gold-bearing precious metal solution was tested using inductively coupled plasma atomic emission spectrometry (ICP-AES), and the analytical method was performed according to the procedure specified in GB / T 11067.7-2024 "Chemical Analysis Methods for Silver Part 7: Determination of Gold and Palladium Contents - Inductively Coupled Plasma AES". The gold leaching rate was determined for both the leaching tailings and the gold-bearing precious metal solution to cross-validate the accuracy and reliability of the data.

[0048] In some embodiments, crushing the gold-bearing mineral material includes crushing the gold-bearing mineral material to a particle size of ≤5cm, where the mineral particles account for 75%-85% of the total mass of the gold-bearing mineral material.

[0049] In this embodiment, 75%-85% of the gold-bearing mineral material has a particle size ≤5cm, with coarse particles predominating overall. This forms a highly porosity, well-connected but not overly dense ore layer, allowing the reagent solution to penetrate the entire ore pile uniformly and rapidly. This improves the contact efficiency between the mineral particles and the reagent, reducing leaching blind zones. The chemical pore-forming and catalytic oxidation processes dissolve minerals and release gases, which may cause ore particle expansion or the formation of secondary fine mud. Within this particle size range, the pore volume between mineral particles can accommodate these expansion volumes and fine particles, reducing the risk of pore blockage and maintaining stable permeability of the ore layer throughout the leaching cycle.

[0050] In some embodiments, the rinsing injection flow rate is 12-14 L / (m³). 2 ·h).

[0051] In this embodiment, 12-14 L / (m 2 A flow rate of 12-14 L / (m³) allows a continuous and stable thin liquid film to form on the surface of the mineral particles. This film serves as the core site for the surface coordination reaction between glycine and gold ions. The liquid film covers both the surface of the ore and the inner surface of internal fractures, increasing the effective reaction area and improving the leaching rate. 2 At a flow rate of h), the flow state is slow laminar flow, which is conducive to the smooth and continuous flow of the reagent system in the interparticle pores under gravity, thereby improving mass transfer efficiency.

[0052] In some embodiments, cyclic rinsing is performed at ambient temperature and pressure.

[0053] In this embodiment, thiosulfate decomposes rapidly under heating conditions, generating ineffective sulfate ions and passivation film elemental sulfur. Glycine may also undergo deamination under high temperature and strong alkaline conditions. This reagent system contains multiple temperature-sensitive organic and inorganic components, minimizing reagent decomposition losses under room temperature conditions and improving reagent stability and utilization. The chelation reaction of glutamic acid and iron can be completed rapidly at room temperature with good selectivity. Heating may cause other impurity metals to leach out simultaneously, increasing reagent loss and purification difficulty. Rinsing at room temperature can maintain the leaching efficiency of the reagent. During atmospheric pressure rinsing, the liquid spreads on the ore surface in the form of a thin film, and the pore space is still filled with air. By providing dissolved oxygen, the mass transfer efficiency of catalytic oxidation and leaching reactions can be improved. Through circulating rinsing, unreacted reagent is repeatedly sprayed back to the ore pile, continuously exerting leaching efficiency, improving reagent utilization, and reducing process costs. During the circulation process, the gold concentration in the solution gradually accumulates and increases, forming a concentration gradient, further promoting the continuous positive leaching reaction. Meanwhile, the low-flow circulation increases the gold concentration in the gold-containing precious solution, reducing the difficulty of subsequent adsorption and recovery.

[0054] In some embodiments, the rinsing cycle is 40-45 days.

[0055] In this embodiment, due to the long heap leaching test cycle and numerous interfering factors, a numerical simulation study was first conducted on the heap leaching process of the glycine-sodium thiosulfate-organic ammonium salt synergistic leaching agent in a 10m thick homogeneous ore body based on a three-dimensional seepage-reactive solute transport model. The model generalizes the 10m thick heap leaching site model into a three-dimensional, homogeneous, isotropic reactive solute transport system, with a model size of 1.0m × 1.0m × 10.0m. Considering that the established model is generalized as a homogeneous and isotropic system, the actual dimensions of the site heap leaching model can be obtained by scaling the simulation results proportionally along the XY plane, such as a heap leaching column height of 1m, an inner diameter of 100cm, and a mineral accumulation height of 0.8m. The model uses a three-dimensional XYZ regular grid with a grid accuracy of 0.1m, resulting in 10,000 numerical grids after numerical discretization. Simulation results show that the injection flow rate per unit area has a decisive influence on the optimal cycle required to achieve complete leaching: for example... Figure 1 As shown, the peak gold leaching concentration in the heap leaching column can be reached within a 40-45 day cyclic leaching cycle. Considering both leaching efficiency and time cost, when the injection flow rate is 13 L / (m³), the optimal leaching concentration is achieved. 2 When h), the optimal leaching period is 41.5 days. If the leaching is carried out based on the above simulation results and an actual ore body test is conducted, the leaching period can be set to 42 days.

[0056] In some embodiments, the deviation between the gold slag leaching rate and the gold liquid phase leaching rate is ≤1% and is considered valid data.

[0057] In this embodiment, the gold leaching rate is calculated simultaneously for both the solid-phase leaching tailings and the liquid-phase gold-containing precious solution. The leaching rate is calculated based on the tailings, and the liquid-phase gold leaching rate is used as an auxiliary detection method to eliminate errors caused by measurement mistakes, equipment adsorption, and ore pile retention, ensuring the accuracy and reliability of the data and the reliability of the process.

[0058] In some embodiments, the gold-bearing mineral material includes one or more of the following: oxidized heap leaching residue, gold-bearing roasted sand with a gold content of 1-10 g / t, and gold ore with a gold grade of 0.5-1.5 g / t.

[0059] In this embodiment, the gold content in the oxidized heap leaching residue, the low-grade gold-bearing roasted sand with a gold content of 1-10 g / t, and the low-grade gold ore with a gold content of 0.5-1.5 g / t are low, the impurity content is high, and the gold is encapsulated by gangue, making it difficult to dissociate. The multi-stage synergistic reagent system of this application systematically and precisely overcomes the above difficulties through its inherent four mechanisms of chemical pore formation, catalytic oxidation, synergistic coordination, and automatic balancing, thereby achieving efficient gold leaching.

[0060] The following are some specific embodiments. It should be noted that the embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they shall be performed in accordance with the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be obtained commercially.

[0061] Example 1 The multi-element content of the gold-bearing minerals used in the experiment is shown in Table 1 below, and the relative content measurement results of the minerals are shown in Table 2 below. Scanning electron microscope images of gold encapsulated in pyrite in the raw ore are shown below. Figure 2 As shown: Table 1. Results of multi-element analysis of raw ore Table 2. Measurement results of relative mineral content in ores The gold-bearing mineral material is crushed to a particle size of 5cm, which accounts for more than 80% of the total mass of the material. Then it is added to a heap leaching column with a height of 1m and an inner diameter of 100cm, and the mineral accumulation height is 0.8m. A gold leaching agent system based on glycine and sodium thiosulfate was added from the top of the heap leaching column. The glycine concentration was 20 g / L, sodium thiosulfate concentration was 10 g / L, glutamic acid concentration was 2 g / L, nano-sized molybdenum disulfide concentration was 0.2 g / L, and polyvinyl ammonium phosphate concentration was 0.2 g / L. The leaching was carried out from top to bottom at room temperature and pressure under a pH of 9.0, with the injection flow rate of the gold leaching agent system controlled at 13 L / (m³). 2 •h), the lower part collects the outflowing leachate, which is then pumped to the upper part of the heap leaching column and leached for 42 days to obtain gold-bearing solution and mineral tailings. The gold content in the tailings of mineral leaching was determined by fire assay. The analytical method was performed according to the fire assay method specified in GB / T 7739.1-2019 "Chemical Analysis Methods for Gold Concentrates Part 1: Determination of Gold and Silver Contents". The gold leaching rate was calculated as shown in formula (I). In formula (I), η1 represents the gold leaching rate by slag, in %; m1 represents the mass of the original leached sample, in g; β1 represents the grade of the original leached sample, in g / t; m2 represents the mass of the residue after leaching, in g; and β2 represents the grade of the residue after leaching, in g / t.

[0062] The gold-containing precious liquid was detected by inductively coupled plasma optical emission spectrometry (ICP-OES). The procedure was performed according to the method specified in GB / T11067.7-2024 "Chemical Analysis Methods for Silver - Part 7: Determination of Gold and Palladium Content - Inductively Coupled Plasma Optical Emission Spectrometry" to obtain the gold concentration in the precious liquid and calculate the gold leaching rate, as shown in formula (II). ; Formula (II): Where η2 represents the liquid phase leaching rate of gold, in %; m1 represents the mass of the original leaching sample, in g; β1 represents the grade of the original leaching sample, in g / t; C represents the concentration of gold in the gold-containing precious solution, in mg / L; and V represents the volume of the gold-containing precious solution, in L. The leaching rate is determined by slag, and the liquid phase leaching rate of gold is used as an auxiliary detection method. The error between the two methods is less than 1% as valid data, thus obtaining the gold leaching rate of Example 1.

[0063] Examples 2-5 and Comparative Examples 1-4 The difference between Example 1 and Example 2 is that the glycine mass concentration is different in the gold immersion agent system. The rest is roughly the same as in Example 1, and will not be repeated here.

[0064] Table 3. Gold leaching rates in Examples 1-5 and Comparative Examples 1-4 As shown in Table 3, as the glycine concentration increased from 0 g / L to 100 g / L, the gold leaching rate gradually increased from 6% to 80% when leached by sodium thiosulfate alone. However, the leaching rate remained stable when the glycine concentration exceeded 50 g / L, indicating that the synergistic effect of glycine and sodium thiosulfate can significantly improve the gold leaching efficiency, while sodium thiosulfate alone can leach some gold, but the effect is extremely limited.

[0065] Examples 6-8 and Comparative Examples 5-13 The difference between Example 1 and Example 2 is that the mass concentration of sodium thiosulfate in the gold immersion reagent system is different. The rest is roughly the same as in Example 1 and will not be repeated here.

[0066] Table 4. Leaching rates of gold in Examples 1, 3-4, 6-8 and Comparative Examples 5-13 Note: "—" indicates that the gold leaching rate is less than 1%, which is within the experimental error range and is considered as a failure to achieve effective gold leaching.

[0067] As shown in Table 4, when the mass concentration of sodium thiosulfate is zero (Comparative Examples 5-7), the leaching rate of gold cannot be detected regardless of the change in glycine concentration. This is because glycine alone lacks the necessary oxidizing power to oxidize elemental gold into monovalent gold ions. The dissolution of gold cannot be achieved solely through the coordination effect of glycine, indicating the necessity of sodium thiosulfate as an oxidizing agent.

[0068] When the sodium thiosulfate concentration was 5 g / L (Comparative Examples 8-10), the gold leaching rate was only 37%-51%, significantly lower than the 70%-78% leaching rate when sodium thiosulfate concentration was 10 g / L at the same glycine concentration. This is because the sodium thiosulfate concentration was too low to provide a sufficient concentration of thiosulfate ions to participate in the oxidation and coordination of gold, severely limiting the gold dissolution reaction. However, when the sodium thiosulfate concentration was increased to 10-15 g / L (Examples 1, 3, 4, 6, 7, 8), the leaching rate reached 70%-78%, and the leaching effect of 10 g / L and 15 g / L was basically the same. This indicates that within this concentration range, sodium thiosulfate is sufficient to meet the requirements for gold oxidation and coordination, and further increasing the concentration will not further improve the leaching rate. Based on economic efficiency, a sodium thiosulfate concentration of 10 g / L is preferred.

[0069] When the sodium thiosulfate concentration was further increased to 50 g / L (Comparative Examples 11-13), the gold leaching rate actually decreased to 62%-65%, which was lower than the leaching rate at the optimal concentration. This is because excessive sodium thiosulfate is more likely to undergo self-oxidative decomposition in the leaching system, generating byproducts such as polythionates. This not only consumes the effective components but may also produce a sulfide passivation film covering the gold surface, hindering further dissolution of gold and thus reducing the leaching efficiency.

[0070] Examples 9-11 and Comparative Examples 14-16 The difference between Example 1 and Example 2 is that the mass concentration of glutamic acid in the gold immersion agent system is different. The rest is roughly the same as in Example 1 and will not be repeated here.

[0071] Table 5. Leaching rates of gold in Examples 1, 9-11, and Comparative Examples 14-16 As shown in Table 5, when the glutamic acid concentration was 0 g / L (Comparative Example 14), the gold leaching rate was only 26%, significantly lower than the data of the example after adding glutamic acid. This is because without glutamic acid, the system's ability to chelate and attack iron ions in sulfide minerals is weak, and it cannot effectively destroy the dense structure of pyrite and pyrrhotite, making it difficult to expose the encapsulated gold. Only glycine and sodium thiosulfate can dissolve a small amount of surface gold, resulting in limited leaching effect. When the glutamic acid concentration was only 0.5 g / L (Comparative Example 15), the leaching rate increased to 48%, but it was still lower than the level of the example. This indicates that although extremely low concentrations of glutamic acid can exert a certain iron chelating effect, it is not enough to fully etch out sufficient chemical channels. When the glutamic acid concentration increased from 1 g / L (Example 9) to 2 g / L (Example 1), the gold leaching rate significantly increased from 63% to 70%. When the concentration was further increased to 3 g / L (Example 10), the leaching rate further increased to 74%, and reached 75% at 4 g / L (Example 11). This indicates that as the concentration of glutamic acid increases, its dicarboxyl structure continuously enhances its ability to chelate and extract iron ions from the surface of sulfide minerals, enabling it to etch more and deeper chemical channels in the mineral matrix, thereby continuously increasing the exposure rate of the encapsulated gold and promoting the synchronous dissolution of gold.

[0072] When the glutamic acid concentration was further increased to 5 g / L (Comparative Example 16), the gold leaching rate was still 75%, which was basically the same as that at 4 g / L. This indicates that when the glutamic acid concentration reaches about 4 g / L, it is sufficient to fully chelate the iron ions dissolved on the mineral surface and in the solution. Further increasing the concentration will not further improve the leaching effect. Considering the overall cost, the preferred mass concentration of glutamic acid is 1-4 g / L.

[0073] Examples 12-14 and Comparative Examples 17-28 The difference between Example 1 and Example 2 is that the mass concentrations of glutamic acid and nano-sized molybdenum disulfide are different in the gold immersion reagent system. The rest is roughly the same as in Example 1 and will not be repeated here.

[0074] Table 6. Leaching rates of gold in Examples 1, 9-15, and Comparative Examples 17-28 Table 6 shows that without the addition of nano-sized molybdenum disulfide (Comparative Examples 17-20), the gold leaching rate was only 47%-54%, and the increase in leaching rate was limited with increasing glutamic acid concentration. This indicates that the iron chelation effect of glutamic acid alone is insufficient to fully disrupt the dense structure of pyrite and pyrrhotite, resulting in insufficient gold exposure and limited leaching effect. When the molybdenum disulfide addition was 0.1 g / L (Comparative Examples 21-24), the leaching rate increased to 57%-62%, but it was still lower than the 63%-75% achieved with 0.2 g / L molybdenum disulfide at the same glutamic acid concentration. This indicates a significant positive synergistic effect between the catalytic effect of molybdenum disulfide and the chelation pore-forming effect of glutamic acid, but the catalytic ability was not fully utilized at lower concentrations. When the molybdenum disulfide (Mo) disulfide concentration increased to 0.2-0.3 g / L (Examples 1, 9-15), the leaching rate reached 63%-75%, and the leaching effect of 0.2 g / L and 0.3 g / L was basically the same, significantly better than the control group without Mo or with lower concentrations of Mo. This is because the layered molybdenum active sites of Mo, through interfacial electron transfer, catalyze the breakage of Fe-S bonds, forming a combined pore-forming mechanism of catalytic breakage and chemical extraction with the dicarboxyl chelate of iron ions by glutamic acid. This effectively etches out chemical channels, allowing the encapsulated gold to be fully exposed and dissolved simultaneously. Minerals collected after 3 days of dissolution in Example 1 were examined using a scanning electron microscope. Scanning electron microscopy revealed the corrosion-formed channels in the pyrite. Figure 3 As shown, this phenomenon ensures the subsequent leaching of gold. However, when the amount of molybdenum disulfide added is further increased to 0.5 g / L (comparative examples 25-28), the leaching rate decreases instead, indicating that excessive molybdenum disulfide solid particles may agglomerate and cover the exposed gold surface, hindering the contact between the leaching agent and the gold. Considering overall cost, the optimal addition amount of nano-sized molybdenum disulfide is around 0.2 g / L, and the synergistic effect is most significant when combined with 1-4 g / L of glutamic acid.

[0075] Examples 16-19 and Comparative Examples 29-31 The difference between Example 1 and Example 2 is that the mass concentration of polyvinyl alcohol ammonium phosphate is different in the gold immersion agent system. The rest is the same as in Example 1 and will not be repeated here.

[0076] Table 7. Leaching rates of gold in Examples 1, 16-19, and Comparative Examples 29-31 Note: The concentration change of sodium thiosulfate was determined using the iodometric method, as follows: 1. Method Principle: The elemental sulfur in the leachate was removed by filtration, and the solution was acidified with acetic acid to control the pH value to around 6. Formaldehyde was used to remove sulfite ions from the solution, and then sodium thiosulfate was determined by iodometric titration. The reaction equation is: 2Na2S2O3+I2=Na2S4O6+2NaI.

[0077] 2. Reagents: Standard iodine solution: 0.1 mol / L; Starch indicator: 0.5%; Acetic acid solution: 10%; Formaldehyde solution: 25%, neutralized to neutral with 0.5 mol / L NaOH solution.

[0078] 3. Measurement methods and calculations: Pipette 5 mL of the filtered leachate into a 250 mL Erlenmeyer flask, add 10 mL of 10% acetic acid solution to acidify, then add 5 mL of 25% neutral formaldehyde solution, shake well, let stand for 2 min, add starch indicator, and titrate with 0.1 mol / L standard sulfonate solution until the solution turns blue (no color change after 30 s), which is the endpoint. The calculation formula is: Na2S2O3 (g / L) = (158×C×V) / V0 Where: C—concentration of standard iodine solution, mol / L; V—Volume of standard iodine solution consumed, in mL; V0—Sampling volume, mL; 158—Molar mass of Na2S2O3.

[0079] Table 7 shows that as the concentration of polyvinyl ammonium phosphate increased from 0 g / L to 0.5 g / L, the consumption rate of sodium thiosulfate decreased significantly from 39% to 6%, while the gold leaching rate steadily increased from 61% to 72%. However, when the concentration further increased to 0.6 g / L and 1.0 g / L, the sodium thiosulfate consumption rate remained at 6%, but the gold leaching rate actually decreased to 65% and 63%, respectively. This indicates that an appropriate amount of polyvinyl ammonium phosphate can effectively inhibit the oxidative decomposition of sodium thiosulfate and improve the gold leaching efficiency, while excessive addition leads to a decrease in the leaching rate. Considering both the gold leaching rate and the sodium thiosulfate consumption rate, the optimal concentration of polyvinyl ammonium phosphate is 0.1-0.5 g / L.

[0080] Conclusions: The multi-stage synergistic reagent system constructed in this invention—polyvinyl alcohol ammonium phosphate-stabilized sodium thiosulfate—molybdenum disulfide catalytic pre-oxidation of sulfide ores—glutamic acid chelation of iron ions for chemical pore formation—glycine and sodium thiosulfate synergistic gold leaching—exhibits significant advantages in heap leaching of low-grade gold-bearing sulfide ores. The introduction of polyvinyl alcohol ammonium phosphate significantly reduces the decomposition rate of sodium thiosulfate during the leaching cycle, resulting in a significant reduction in reagent consumption. The combined action of molybdenum disulfide nanocatalyst and glutamic acid can etch dense nano- to micron-sized chemical channels on the surface of pyrite and pyrrhotite in a short time, fully exposing the gold particles that were originally densely encapsulated by sulfide minerals. Furthermore, the mixed ligand gold leaching system of glycine and sodium thiosulfate achieves simultaneous dissolution of the exposed gold, significantly increasing the total gold leaching rate compared to the single sodium thiosulfate process, while completely avoiding the use of cyanide, thus significantly improving environmental safety.

[0081] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing embodiments by combining some of the constituent elements, are also included in the scope of this application without departing from the spirit of this application.

[0082] Furthermore, although this application has been described with reference to preferred embodiments, various modifications can be made thereto and components can be replaced with equivalents without departing from the scope of this application. In particular, the technical features mentioned in the various embodiments can be combined in any manner, provided there is no structural conflict. This application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A gold leaching agent system based on glycine and sodium thiosulfate, characterized in that, include: A mixture of ligand immersion gold agent, synergistic catalyst, and sodium thiosulfate stabilizer; among which, The mixed ligand immersion gold agent includes glycine and sodium thiosulfate, the co-catalyst includes glutamic acid and molybdenum disulfide, and the sodium thiosulfate stabilizer is polyvinyl ammonium phosphate. The glycine has a mass concentration of 10-50 g / L, the sodium thiosulfate has a mass concentration of 10-15 g / L, the glutamic acid has a mass concentration of 1-4 g / L, the molybdenum disulfide has a mass concentration of 0.2-0.3 g / L, and the polyvinyl alcohol ammonium phosphate has a mass concentration of 0.1-0.5 g / L.

2. The gold leaching agent system based on glycine and sodium thiosulfate according to claim 1, characterized in that, The mass ratio of the glycine to the sodium thiosulfate is (1-5):

1.

3. The gold leaching agent system based on glycine and sodium thiosulfate according to claim 1, characterized in that, The mass ratio of the glutamic acid to the molybdenum disulfide is (5-20):

1.

4. The gold leaching agent system based on glycine and sodium thiosulfate according to claim 1, characterized in that, The pH range for the use of the gold immersion reagent system is 8.0-10.

0.

5. A heap leaching process for gold-bearing minerals, characterized in that, The gold leaching process using the glycine and sodium thiosulfate-based leaching agent system as described in any one of claims 1-4 includes the following steps: After crushing the gold-bearing mineral material, it was added to the heap leaching column; The gold leaching agent system based on glycine and sodium thiosulfate is added to the upper part of the heap leaching column and circulated and leached under a pH of 8.0-10.0 environment. The leachate flowing out from the lower part is collected to obtain gold-containing precious solution and mineral leaching tailings. The gold leaching tailings were tested by fire assay, and the gold leaching rate was calculated as shown in formula (I): Formula (I): where η1 represents the gold leaching rate by slag, in %; m1 represents the mass of the original leached sample, in g; β1 represents the grade of the original leached sample, in g / t; m2 represents the mass of the residue after leaching, in g; β2 represents the grade of the residue after leaching, in g / t. The concentration of gold in the gold-containing precious liquid was determined by inductively coupled plasma atomic emission spectrometry (ICP-AES), and the liquid-phase leaching rate of gold was calculated as shown in equation (II): ； Formula (II): where η2 represents the liquid phase leaching rate of gold, in %; m1 represents the mass of the original leaching sample, in g; β1 represents the grade of the original leaching sample, in g / t; C represents the concentration of gold in the gold-containing precious solution, in mg / L; and V represents the volume of the gold-containing precious solution, in L.

6. The heap leaching process for gold-bearing minerals according to claim 5, characterized in that, The crushing of the gold-bearing mineral material includes crushing the gold-bearing mineral material until the mineral particles with a particle size of ≤5cm account for 75%-85% of the total mass of the gold-bearing mineral material.

7. The heap leaching process for gold-bearing minerals according to claim 5, characterized in that, The injection flow rate for the rinsing is 12-14 L / (m³). 2 ·h); and / or, The cyclic rinsing is carried out at normal temperature and pressure.

8. The heap leaching process for gold-bearing minerals according to claim 5, characterized in that, The cyclic rinsing process takes 40-45 days.

9. The heap leaching process for gold-bearing minerals according to claim 5, characterized in that, The data is considered valid if the deviation between the gold slag leaching rate and the gold liquid phase leaching rate is ≤1%.

10. The heap leaching process for gold-bearing minerals according to claim 5, characterized in that, The gold-bearing mineral materials include one or more of the following: oxidized heap leaching residue, gold-bearing roasted sand with a gold content of 1-10 g / t, and gold ore with a gold grade of 0.5-1.5 g / t.

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