Gradient separation-enhanced recovery method for micro-fine particle dip dyeing type gold ore

Abstract

The invention relates to a micro-fine particle dip dyeing type gold ore cascade separation-enhanced recovery method which comprises the following steps: first-stage grinding and grading of raw ore: carrying out two-stage grinding and grading on the raw ore to obtain graded overflow with 50-65% of-325 meshes; first-stage whole-size-fraction flotation is conducted, specifically, flotation is conducted on graded overflow, and gold concentrate 1 and first-stage flotation tailings are obtained; second-stage ore grinding and classified desliming are conducted, specifically, first-stage flotation tailings are subjected to ore grinding and classified into coarse-fraction slurry with the particle size being + 20 microns and fine-fraction slurry with the particle size being-20 microns; second-stage coarse-fraction flotation is conducted, specifically, flotation is conducted on coarse-fraction slurry with the particle size of + 20 microns, and gold concentrate 2, tailings 1 and middlings are obtained; third-stage middling regrinding: regrinding the middling until the middling with-400 meshes accounts for 80%-90%; and third-stage fine fraction enhanced flotation is conducted, specifically, flotation is conducted on the middling regrinding product and the-20-micrometer fine fraction slurry, and gold concentrate 3 and tailings 2 are obtained. The process of stage grinding, cascade separation and enhanced recovery is adopted, and differentiated equipment configuration, medicament systems and process parameters are adopted in stages and size fractions, so that the gold-loaded minerals of all the size fractions are efficiently recovered in the optimal separation environment.

Description

Technical Field

[0001] This invention belongs to the field of mineral processing technology, specifically relating to a cascade separation and enhanced recovery method for fine-grained disseminated gold ore, particularly for refractory gold ore resources with fine-grained and highly unevenly distributed gold-bearing minerals. Background Technology

[0002] Fine-grained disseminated gold deposits are an important type of gold resource in my country, with proven reserves of approximately 1,700 tons, accounting for more than 50% of the country's total proven gold resources. In this type of deposit, gold is typically dispersed in micron-sized (or even nanon-sized) disseminated forms within pyrite, arsenopyrite, and other metal sulfides and their aggregates, or encapsulated or partially encapsulated by gangue minerals such as quartz, silicates, and carbonates. Some gold also exists in a non-free colloidal adsorbed form. The gold-bearing minerals exhibit extremely uneven particle size distribution, with a large number of fine-grained particles smaller than 10 μm, making it a typical difficult-to-process and utilize gold resource.

[0003] Currently, the main technical problems in processing fine-grained disseminated gold deposits are as follows: 1. Conventional "fine grinding-full-size flotation" processes suffer from low recovery rates and high energy consumption: Such fine or ultrafine grinding often leads to over-grinding of minerals, generating a large amount of fine mud. This fine mud has characteristics such as small mass, low inertia, large specific surface area, high surface energy, and strong adsorption capacity. During the flotation process, the fine gold-loaded mineral particles are difficult to effectively detach from the hydrodynamic streamlines and collide with bubbles for mineralization. At the same time, it causes an increase in pulp viscosity, yield stress, and turbulence damping, severely deteriorating the flotation kinetic environment. In addition, the mutual covering and agglomeration of fine particles also reduce the differences in mineral surface properties and the selectivity of flotation reagents, seriously affecting the flotation effect.

[0004] 2. Conventional "pretreatment-carbon-in-pulp leaching" processes have significant limitations: While pretreatment methods such as oxidative roasting, hot-press oxidation, and chemical oxidation can improve gold leaching rates, they suffer from complex processes, high equipment requirements, high processing costs per ton of ore, and severe environmental pollution. Biological oxidation methods have drawbacks such as demanding microbial culture conditions, slow reaction rates, and poor adaptability, limiting their large-scale industrial application. In direct carbon-in-pulp leaching, even ultrafine grinding cannot fully expose the encapsulated gold, and the mudding of fine particles severely deteriorates the activated carbon adsorption-desorption process, resulting in generally low overall gold recovery rates.

[0005] 3. Lack of effective recovery technology for fine-grained gold-bearing minerals: Traditional flotation and carbon leaching processes cannot effectively recover fine-grained gold-bearing mineral particles in this type of ore, and are also subject to the adverse effects of fine-grained minerals, resulting in low recovery rates and high recovery costs.

[0006] Therefore, there is an urgent need to develop a high-efficiency, low-cost mineral processing technology that is tailored to the characteristics of fine-grained disseminated gold ores and can achieve differentiated sorting and recovery, in order to solve the common problems in the industry. Summary of the Invention

[0007] This invention provides a method for cascade separation and enhanced recovery of fine-grained disseminated gold ore. Based on the ore characteristics of fine and highly unevenly distributed gold-bearing minerals, this method employs a "stage grinding-cascade separation-enhanced recovery" technical approach. According to the different requirements of different particle sizes for the flotation kinetic environment, it recovers gold-bearing mineral particles of different sizes in stages. In particular, it utilizes micron-sized cavitation bubble technology for narrow-scale enhanced flotation of fine and micro-fine particles, reconstructing the differences in surface properties of fine particles, and achieving comprehensive and efficient enrichment of fine-grained disseminated gold ore.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A method for cascade separation and enhanced recovery of fine-grained disseminated gold ore includes the following steps: (1) One-stage grinding and classification of raw ore: The raw ore is subjected to two-stage grinding and classification. The overflow fineness of the first stage of grinding and classification is -200 mesh, accounting for 45%~55%, and the overflow fineness of the second stage of grinding and classification is -325 mesh, accounting for 50%~65%. Based on the uneven particle size distribution of gold-bearing minerals in the ore, this invention employs multi-stage grinding for selective dissociation, avoiding the over-grinding and high energy consumption caused by the traditional "overall fine grinding" process. This step first uses a single-stage grinding process to initially dissociate the coarser gold-bearing minerals, followed by a single-stage grinding process to expose the coarse aggregates, while the fine inclusions remain partially dissociated. This addresses the problem of deteriorating slurry rheological properties in subsequent separation processes from the outset, creating the preconditions for cascade separation.

[0009] (2) First stage full-size flotation: Add combined activator AR, copper sulfate, combined collector CR and frother 2# oil to the two-stage grinding and classification overflow slurry obtained in step (1) to perform first stage roughing 1; add copper sulfate and combined collector CR to the tailings of first stage roughing 1 to perform first stage roughing 2; after merging the foam from the two roughing stages, add dispersant water glass to perform three stages of cleaning, and return the middlings in order. The foam from first stage cleaning 3 is gold concentrate 1, and the tailings from roughing 2 are the tailings from first stage flotation. This step utilizes differentiated adaptation of flotation reagents and flotation machine operating parameters to perform low-turbulence separation of fully liberated coarse-grained gold-bearing minerals. On one hand, a composite activator, AR and copper sulfate, is used. Through the synergistic effects of sodium carbonate adjusting the pulp pH, sodium sulfide oxidizing the surface, and copper ion enhancing adsorption, multi-level activation of the gold-bearing mineral surface is achieved. Furthermore, differentiated bubble sizes are employed to balance the inertial collision efficiency of coarse particles on the bubble surface with the fluid shear force, reducing the desorption probability and enabling stable mineralization and flotation of the bubbles in low-turbulence conditions.

[0010] (3) Two-stage grinding and classification: The first-stage flotation tailings obtained in step (2) are subjected to two-stage grinding and classification, with a grinding fineness of -325 mesh accounting for 75%~90%; the overflow is classified and deslimed to separate +20μm coarse slurry and -20μm fine slurry. This step involves a second-stage grinding process to remove unliberated fine-grained gold-bearing minerals from the tailings of the first-stage flotation, enabling them to be liberated individually. The grinding products are then classified and deslimed according to a 20μm particle size, transforming "wide-size flotation" into "narrow-size separation." This creates conditions for subsequent differentiated separation and solves the problem of reduced reagent selectivity caused by "fine mud covering" and "agglomeration" in traditional fine grinding-full-size flotation.

[0011] (4) Two-stage coarse flotation: Add copper sulfate, combined collector CR and frother 2# oil to the +20μm coarse slurry obtained in step (3) for two-stage roughing 1. Add copper sulfate and combined collector CR to the tailings of two-stage roughing 1 for two-stage roughing 2. After merging the foam from the two roughing stages, perform two cleaning stages. The middlings from the cleaning stages are returned sequentially. The concentrate from the second cleaning stage is gold concentrate 2. Add combined activator AR and combined collector CR to the tailings of the second roughing stage for two-stage scavenging 1. Add combined activator AR and combined collector CR to the tailings of two-stage scavenging 1 for two-stage scavenging 2. The tailings from two-stage scavenging 2 are tailings 1. The middlings from the two scavenging foam cleaning stages 1 are merged into regrinding middlings. This step mainly focuses on the targeted recovery of the separated +20μm coarse-grained gold-loaded mineral particles. Its flotation mechanism is similar to that of step (2), but two additional scavenging processes are added to deeply recover the gold-loaded mineral particles. During the scavenging process, a combined activator AR is used to enhance the activation of medium and fine-grained gold-loaded minerals with surface oxidation or contamination by utilizing its synergistic effect with copper sulfate.

[0012] (5) Three-stage middlings regrinding: The middlings obtained in step (4) are regrinded and classified, and the overflow fineness of the classification is -400 mesh, accounting for 80%~90%; This step avoids the repeated recycling of wide-sized materials through the design of middlings regrinding. Regrinding can further liberate and expose fine intergrowths and inclusions (especially gold-bearing iron ore particles wrapped in gangue), forming narrow-sized, highly liberated material to be processed, thus providing ideal feed with a liberation degree of >85% for the three-stage fine-grained enhanced flotation.

[0013] (6) Three-stage fine-grained enhanced flotation: The graded overflow slurry obtained in step (5) and the -20μm micro-fine particle slurry obtained in step (3) are combined to form the fine-grained material to be processed; copper sulfate and combined collector CR are added to the fine-grained material to carry out three-stage roughing, and the foam of the three-stage roughing is directly used for one cleaning, and the cleaned foam is gold concentrate 3. Copper sulfate and combined collector CR are added to the roughing tailings to carry out one scavenging, and the scavenged tailings are tailings 2; the cleaned tailings and scavenged concentrate are returned to the roughing stage; wherein, both roughing and cleaning adopt micron bubble flotation technology.

[0014] This step employs micron-sized cavitation bubble technology for fine-grained gold-bearing mineral particles. Leveraging the small volume, large specific surface area, and slow rising velocity of micron-sized bubbles, the collision probability between fine particles and bubbles is significantly increased, enabling efficient mineralization and flotation of the micron-sized bubbles. Simultaneously, the high-energy, small-scale eddies generated by the eddy generator and circulating pressure create a more suitable hydrodynamic environment for fine-particle separation. High-selectivity separation can be achieved with the addition of a small amount of slurry dispersant, resulting in the efficient enrichment of fine-grained gold minerals.

[0015] Furthermore, the combined activator AR is a mixture of Na2CO3 and Na2S in a ratio of 30:1; the combined collector CR is a mixture of MA (a xanthate collector) and BK721 (a sulfur-nitrogen collector) in a ratio of 10:1.

[0016] Furthermore, the reagent regimes for each stage of flotation are as follows: In step (2), the first roughing stage 1 adds 300-600 g / t of combined activator AR, 50-150 g / t of copper sulfate, 120-300 g / t of combined collector CR, and 6 g / t of No. 2 oil; the second roughing stage adds 20-50 g / t of copper sulfate and 60-150 g / t of combined collector CR; and the first cleaning stage 1 adds 100-300 g / t of water glass. In step (4), copper sulfate 25~75 g / t, combined collector CR 30~75 g / t, and No. 2 oil 2~6 g / t are added to the second-stage roughing 1; copper sulfate 10~20 g / t and combined collector CR 15~50 g / t are added to the second-stage roughing 2; combined activator AR 5~15 g / t and combined collector CR 15~30 g / t are added to both the second-stage scavenging 1 and the second-stage scavenging 2; and water glass 0-200 g / t is added to the second-stage roughing 1. In step (6), copper sulfate 10~20 g / t and combined collector CR 15~30 g / t are added for roughing; copper sulfate 20~50 g / t and combined collector CR 10~20 g / t are added for scavenging.

[0017] Furthermore, in step (1), the grinding concentration of both stages is 60%~75%, and the grading concentration of both stages is 40%~60%; in step (3), the grinding concentration of the two stages is 60%~75%, and the grading concentration is 40%~50%; in step (5), the grinding concentration is 60%~75%, and the grading concentration is 35%~50%.

[0018] Furthermore, the pulp concentration for roughing in steps (2) and (4) is 25% to 35%.

[0019] Furthermore, in steps (2) and (4), all flotation processes are carried out using a conventional aerated mechanical stirring flotation machine for low-turbulence separation. The impeller speed is controlled at 1000~1400 r / min (the impeller speed is controlled to regulate the intensity of slurry turbulence). The aeration rate is 0.8~1.4 m³ / (m²·min), the inlet air pressure is >15 kPa, the average diameter of the generated bubbles is 1~5 mm, and the foam layer thickness is <10 cm.

[0020] Furthermore, the roughing and fine selection in step (6) adopts a microbubble flotation device, which generates micron-sized bubbles with a diameter ≤0.5mm by adjusting the inlet and outlet pressure and air volume parameters, wherein the proportion of -0.5mm bubbles is ≥95%.

[0021] Furthermore, the microbubble flotation equipment is selected from one of the following: micro-packed medium flotation column, cyclone static flotation column, or combined column-machine flotation machine.

[0022] Furthermore, the parameters for roughing operations are: suction pump speed of 350~600 r / min, aeration rate of 0.45~0.85 m³ / (m²·h), circulation pressure of 0.15~0.35 MPa, and slurry concentration of 25%~35%; the parameters for cleaning operations are: suction pump speed of 450~700 r / min, aeration rate of 0.15~0.30 m³ / (m²·h), circulation pressure of 0.12~0.25 MPa, and slurry concentration of 20%~25%.

[0023] Furthermore, the sweeping process in step (6) can be performed using conventional flotation equipment or microbubble flotation equipment.

[0024] The beneficial effects of this invention are as follows: This invention targets the ore characteristics of fine-grained disseminated gold deposits with uneven particle size distribution. It adopts a differentiated separation process of "stage grinding - step-by-step separation - enhanced recovery" to separate the beneficiation target into full-grain size and coarse-grained (+20μm) and fine-grained (-20μm) gold-bearing mineral particles. Different equipment configurations, reagent regimes and process control parameters are used for each size to ensure that each size can be recovered in the optimal separation environment. As a result, the total gold recovery rate is significantly increased from 50%~70% in the traditional process to 83%~85%, and the concentrate grade is stabilized at over 30g / t.

[0025] (1) Stage grinding and cascade separation technology transforms “wide particle size material mixing” into “narrow particle size cascade separation” through selective dissociation and 20μm particle size classification, reducing the yield of fine mud from the source, reducing grinding energy consumption, and avoiding the extensive and fuzzy control of separation conditions by traditional coarse and fine particle full-size flotation, thus creating a premise for differentiated separation.

[0026] (2) For coarse and fine gold-bearing minerals, the present invention adopts a step-by-step matching technology of bubble size and flow field environment (instead of the traditional average bubble diameter of 10~20mm), which effectively increases the collision probability between gold-bearing minerals and bubbles and reduces the desorption probability, thereby achieving stable mineralization and flotation of the corresponding material bubbles.

[0027] (3) For fine-grained gold-bearing minerals, this invention uses micron-sized cavitation bubble enhancement technology to generate micron-sized bubbles with a diameter ≤0.5mm (accounting for ≥95%) through microbubble flotation equipment, which greatly increases the probability of bubble-particle collision. At the same time, combined with the high-energy flow state small-scale eddy current constructed by the eddy current generator, it completely solves the industry bottleneck of fine particles being difficult to get rid of streamline mineralization, which increases the recovery rate of this particle size by 15%~20%, promotes the improvement of the total gold recovery rate, and optimizes and reduces the amount of reagents used. This has significant industrial application value for the efficient development of more than 1,700 tons of difficult-to-process fine-grained disseminated gold resources in my country. Attached Figure Description

[0028] Figure 1 This is a flowchart illustrating the principle of a cascaded sorting and enhanced recovery method for fine-particle disseminated gold ore according to the present invention. Figure 2 This is a detailed flowchart of a cascaded sorting and enhanced recovery method for fine-particle disseminated gold ore according to the present invention. Detailed Implementation

[0029] To make the technical problems and solutions solved by the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely for explaining the present invention and are not intended to limit the present invention. Example 1

[0030] Raw Ore #1: A fine-grained disseminated gold ore, with main valuable elements and grades of Au 2.15 g / t and S 1.0%, respectively. Gold mainly exists as gold encapsulated in sulfides, with extremely fine grain sizes, down to 0.27 μm. The main metallic mineral in the ore is pyrite, while the gangue minerals are mainly quartz, dolomite, and muscovite, with minor amounts of potassium feldspar, chlorite, biotite, and calcite. The grain size distribution of the gold-bearing pyrite in the ore is extremely uneven, with most exhibiting a fine-grained disseminated distribution, some particles encapsulated in gangue minerals, and a portion of pyrite occurring as medium- or coarse-grained particles and locally enriched aggregates. The overall pyrite grain size is fine, with approximately 18.50% of the pyrite grains smaller than 0.01 mm. The ore structure is mainly disseminated, followed by speckled and vein-like structures. When the grinding fineness is -200 mesh (90%), the liberation degree of pyrite is only 68%, indicating poor liberation. The ore contains a large amount of muscovite, which has good flotation properties and is prone to mud formation during grinding, thus affecting flotation indicators.

[0031] When using the traditional full-size fine grinding mixed flotation process for recovery, the raw ore is finely ground to -325 mesh in one go, accounting for about 85%. After two roughing, three cleaning and two scavenging processes, a gold concentrate with a yield of 5.24%, a gold grade of 32.37 g / t and a gold recovery rate of 69.25% can be obtained.

[0032] The "cascaded sorting and enhanced recovery" method described in this invention is used to recover raw material #1. The specific steps are as follows: (1) One-stage grinding and classification of raw ore: The raw ore is subjected to two-stage grinding and classification. The overflow fineness of the first-stage grinding and classification is -200 mesh, accounting for 45%~55%, and the overflow fineness of the second-stage grinding and classification is -325 mesh, accounting for about 52%. The grinding concentration of both stages is controlled at 60%~75%, and the classification concentration of both stages is controlled at 40%~60%. (2) Primary full-size flotation: Add 300 g / t of combined activator AR, 50 g / t of copper sulfate, 120 g / t of combined collector CR, and 6 g / t of frother 2# oil to the overflow slurry obtained in step (1) to make the slurry concentration 25%~35% for primary roughing 1; add 50 g / t of copper sulfate and 150 g / t of combined collector CR to the tailings of primary roughing 1 for secondary roughing 2; after merging the froth from the two roughing stages, add 200 g / t of dispersant water glass. The process involves three stages of fine selection, with the middlings returned sequentially. The froth from stage 3 of fine selection is gold concentrate 1, and the tailings from stage 2 of roughing are primary flotation tailings. Both the roughing and fine flotation machines employ conventional aerated mechanical stirring flotation machines for low-turbulence separation. The impeller speed is controlled at 1000~1400 r / min, the aeration rate is 0.8~1.4 m³ / (m²·min), the inlet air pressure is >15 kPa, and the average diameter of the generated bubbles is 1~5 mm with a froth layer thickness <10 cm.

[0033] (3) Secondary grinding and classification: The primary flotation tailings obtained in step (2) are subjected to secondary grinding and classification, with a grinding fineness of approximately 78% -325 mesh; the classification overflow is then classified and deslimed to separate +20μm coarse slurry and -20μm fine slurry; the grinding concentration is 60%~75%, and the classification concentration is 40%~50%; (4) Secondary fine-particle flotation: Add 50 g / t of copper sulfate, 55 g / t of combined collector CR, and 2 g / t of frother 2# oil to the +20μm fine-particle slurry obtained in step (3), with a slurry concentration of 25%~35%, and perform secondary roughing 1. Add 10 g / t of copper sulfate and 35 g / t of combined collector CR to the tailings of secondary roughing 1 for secondary roughing 2. After merging the froth from the two roughing stages, perform two cleaning stages (without adding dispersant water glass). Return the middlings from the cleaning stages sequentially. The concentrate from secondary cleaning 2 is gold concentrate 2. Add 15 g / t of combined activator AR and 28 g / t of combined collector CR to the tailings of secondary roughing 2 for secondary scavenging 1. Add 5 g / t of combined activator AR and 15 g / t of combined collector CR to the tailings of secondary scavenging 1. The process involves two stages of scavenging (2), with the tailings from stage 2 being tailings (1). The middlings from both scavenging stages and the middlings from stage 1 are combined into middlings. The roughing, cleaning, and scavenging stages all employ conventional aerated mechanical stirring flotation machines for low-turbulence separation. The impeller speed is controlled at 1000~1400 r / min, the aeration rate is 0.8~1.4 m³ / (m²·min), the inlet air pressure is >15 kPa, and the average diameter of the generated bubbles is 1~5 mm with a foam layer thickness <10 cm.

[0034] (5) Regrinding of middlings in step (4): The middlings obtained in step (4) are regrinded and classified. The overflow fineness of the classification is about 85% -400 mesh. The grinding concentration is 60%~75% and the classification concentration is 35%~50%.

[0035] (6) Three-stage fine particle enhanced flotation: The graded overflow slurry obtained in step (5) and the -20μm fine particle slurry obtained in step (3) are combined to form the fine particle material to be processed; copper sulfate 15 g / t and combined collector CR 20 g / t are added to the fine particle material for three-stage roughing; the concentrate from the three-stage roughing is directly subjected to three-stage cleaning; the foam from the cleaning is gold concentrate 3; copper sulfate 20 g / t and combined collector CR 15 g / t are added to the tailings from the three-stage roughing. The process involves three stages of scavenging, with the scavenged tailings designated as Tailings 2. Both the three-stage cleaning tailings and the scavenged concentrate are returned to the roughing stage. Both the three-stage roughing and cleaning stages utilize microbubble flotation equipment, generating micron-sized bubbles with a diameter ≤0.5mm by adjusting the inlet and outlet pressures and air flow parameters, with -0.5mm bubbles accounting for ≥95%. The roughing operation parameters are: suction pump speed 500 r / min, aeration rate 0.75 m³ / (m²·h), circulation pressure 0.27 MPa, and pulp concentration 25%~35%. The cleaning operation parameters are: suction pump speed 450 r / min, aeration rate 0.17 m³ / (m²·h), circulation pressure 0.15 MPa, and pulp concentration 20%~25%. Scavenging employs conventional flotation equipment.

[0036] The results obtained were as follows: a gold concentrate (gold concentrate 1 + gold concentrate 2 + gold concentrate 3) with a yield of 5.99%, a gold grade of 30.46 g / t, and a gold recovery rate of 85.25% was obtained. These indicators are superior to those of the whole-size fine grinding mixed flotation process. The specific process indicators are compared in Table 1. Table 1: Comparison of Process Indicators Example 2

[0037] Raw Ore #2: A fine-grained disseminated gold ore, with main valuable elements and grades of Au 2.08 g / t, S 1.24%, As 0.226%, and C 1.83%. The ore oxidation rate is less than 5%, and the processing type is a low-sulfide fine-grained disseminated primary gold ore. Metallic sulfides account for 2.56% of the ore, mainly pyrite and a small amount of arsenopyrite, while metallic oxides account for 2.21%, mainly hematite. Gangue minerals account for 95.23%, mainly quartz and albite, followed by dolomite and sericite. The gold minerals in the ore are mainly microparticles of gold, closely related to sulfides. The gold disseminated grain size is very fine, with microparticles smaller than 10 μm accounting for >78.0%, of which microparticles smaller than 5 μm account for as much as 25%.

[0038] When using the traditional carbon-in-pulp leaching process for recovery, the grinding fineness is -200 mesh with a content of 95%, the pulp concentration is 33%, the pulp pH is 11.5, the alkali treatment time is 2 hours, the green gold reagent is added at 5.0 kg / t, the activated carbon is added at 18 g / L pulp, the leaching time is 40 hours, and the gold leaching rate is less than 60%.

[0039] The "cascaded sorting and enhanced recovery" method described in this invention is used to recover raw material #2. The specific steps are as follows: (1) One-stage grinding and classification of raw ore: The raw ore is subjected to two-stage grinding and classification. The overflow fineness of the first-stage grinding and classification is -200 mesh, accounting for 45%~55%, and the overflow fineness of the second-stage grinding and classification is -325 mesh, accounting for about 63%. The grinding concentration of both stages is controlled at 60%~75%, and the classification concentration of both stages is controlled at 40%~60%. (2) First-stage full-size flotation: Add combined activator AR 400 g / t, copper sulfate 100 g / t, combined collector CR 210 g / t and frother 2# oil 6 g / t to the two-stage grinding and classification overflow slurry obtained in step (1), and the slurry concentration is 25%~35% for first-stage roughing 1; add copper sulfate 35 g / t and combined collector CR 80 g / t to the tailings of first-stage roughing 1 for second-stage roughing 2; after merging the froth from the two roughing stages, add dispersant water glass 300 g / t. The process involves three stages of fine selection, with the middlings returned sequentially. The froth from stage 3 of fine selection is gold concentrate 1, and the tailings from stage 2 of roughing are primary flotation tailings. Both the roughing and fine flotation machines employ conventional aerated mechanical stirring flotation machines for low-turbulence separation. The impeller speed is controlled at 1000~1400 r / min, the aeration rate is 0.8~1.4 m³ / (m²·min), the inlet air pressure is >15 kPa, and the average diameter of the generated bubbles is 1~5 mm with a froth layer thickness <10 cm.

[0040] (3) Two-stage grinding and classification: The primary flotation tailings obtained in step (2) are subjected to two-stage grinding and classification, with a grinding fineness of approximately -325 mesh accounting for about 88%; the classification overflow is classified and deslimed to separate +20μm coarse slurry and -20μm fine slurry; wherein, the grinding concentration is 60%~75% and the classification concentration is 40%~50%; (4) Two-stage coarse flotation: Add 25 g / t of copper sulfate, 30 g / t of combined collector CR, and 6 g / t of frother 2# oil to the +20 μm fine particle slurry obtained in step (3), with a slurry concentration of 25%~35%, and perform two-stage roughing 1. Add 20 g / t of copper sulfate and 15 g / t of combined collector CR to the tailings of two-stage roughing 1 for two-stage roughing 2. After merging the froth from the two roughing stages, perform two cleaning stages (without adding dispersant water glass). Return the middlings from the cleaning stages sequentially. The concentrate from two-stage cleaning stages is gold concentrate 2. Add 15 g / t of combined activator AR and 15 g / t of combined collector CR to the tailings of two-stage roughing 2 for two-stage scavenging 1. Add 15 g / t of combined activator AR and 25 g / t of combined collector CR to the tailings of two-stage scavenging 1. The process involves two stages of scavenging (2), with the tailings from stage 2 being tailings (1). The middlings from both scavenging stages and the middlings from stage 1 are combined into middlings. The roughing, cleaning, and scavenging stages all employ conventional aerated mechanical stirring flotation machines for low-turbulence separation. The impeller speed is controlled at 1000~1400 r / min, the aeration rate is 0.8~1.4 m³ / (m²·min), the inlet air pressure is >15 kPa, and the average diameter of the generated bubbles is 1~5 mm with a foam layer thickness <10 cm.

[0041] (5) Three-stage middlings regrinding: The middlings obtained in step (4) are regrinded and classified, and the overflow fineness of the classification is about 78% -400 mesh; the grinding concentration is 60%~75% and the classification concentration is 35%~50%.

[0042] (6) Three-stage fine-grained enhanced flotation: The graded overflow slurry obtained in step (5) and the -20μm fine-grained slurry obtained in step (3) are combined to form the fine-grained material to be processed; copper sulfate 10 g / t and combined collector CR 30 g / t are added to the fine-grained material for three-stage roughing; the concentrate from the three-stage roughing is directly subjected to three-stage cleaning; the foam from the cleaning is gold concentrate 3; copper sulfate 30 g / t and combined collector CR 10 g / t are added to the tailings from the three-stage roughing. The process involves three stages of scavenging, with the scavenged tailings designated as Tailings 2. Both the three-stage cleaning tailings and the scavenged concentrate are returned to the roughing stage. Both the three-stage roughing and cleaning stages utilize microbubble flotation equipment, generating micron-sized bubbles with a diameter ≤0.5mm by adjusting the inlet and outlet pressures and air flow parameters, with -0.5mm bubbles accounting for ≥95%. The roughing operation parameters are: suction pump speed 350 r / min, aeration rate 0.45 m³ / (m²·h), circulation pressure 0.15 MPa, and pulp concentration 25%~35%. The cleaning operation parameters are: suction pump speed 550 r / min, aeration rate 0.24 m³ / (m²·h), circulation pressure 0.20 MPa, and pulp concentration 20%~25%. Scavenging employs conventional flotation equipment.

[0043] The results obtained were as follows: a gold concentrate (gold concentrate 1 + gold concentrate 2 + gold concentrate 3) with a yield of 5.78%, a gold grade of 30.02 g / t, and a gold recovery rate of 83.43% was obtained. These indicators are superior to those of the carbon-in-pulp leaching process. The specific process indicators are compared in Table 2. Table 2: Comparison of Process Indicators Example 3

[0044] Raw Ore #3: A fine-grained disseminated gold ore, with main valuable elements and grades of Au 1.94 g / t and S 1.39%, respectively. Gold exists primarily as microparticles, mainly distributed within pyrite. Minor amounts of gold are also found in native gold, silver-gold deposits, and other gold minerals. The main metallic mineral in the ore is pyrite, with trace amounts of arsenopyrite, rutile, sphalerite, galena, chalcopyrite, pyrrhotite, and limonite. Gangue minerals are mainly quartz, dolomite, potassium feldspar, diopside, amphibole, and chlorite. The pyrite distribution is uneven, with a high proportion of fine-grained particles. In the -10 μm size range, pyrite accounts for over 10%, appearing as fine particles encased within gangue minerals. Occasionally, pyrite is found intercalated with sulfides such as sphalerite, arsenopyrite, galena, and chalcopyrite within the gangue minerals.

[0045] The "cascaded sorting and enhanced recovery" method described in this invention is used to recover raw material #3. The specific steps are as follows: (1) One-stage grinding and classification of raw ore: The raw ore is subjected to two-stage grinding and classification. The overflow fineness of the first-stage grinding and classification is -200 mesh, accounting for 45%~55%, and the overflow fineness of the second-stage grinding and classification is -325 mesh, accounting for about 57%. The grinding concentration of both stages is controlled at 60%~75%, and the classification concentration of both stages is controlled at 40%~60%. (2) First-stage full-size flotation: Add combined activator AR 600 g / t, copper sulfate 150 g / t, combined collector CR 300 g / t and frother 2# oil 6 g / t to the two-stage grinding and classification overflow slurry obtained in step (1), and the slurry concentration is 25%~35% for first-stage roughing 1; add copper sulfate 20 g / t and combined collector CR 60 g / t to the tailings of first-stage roughing 1 for second-stage roughing 2; after merging the froth from the two roughing stages, add dispersant water glass 150 g / t. The process involves three stages of fine selection, with the middlings returned sequentially. The froth from stage 3 of fine selection is gold concentrate 1, and the tailings from stage 2 of roughing are primary flotation tailings. Both the roughing and fine flotation machines employ conventional aerated mechanical stirring flotation machines for low-turbulence separation. The impeller speed is controlled at 1000~1400 r / min, the aeration rate is 0.8~1.4 m³ / (m²·min), the inlet air pressure is >15 kPa, and the average diameter of the generated bubbles is 1~5 mm with a froth layer thickness <10 cm.

[0046] (3) Two-stage grinding and classification: The primary flotation tailings obtained in step (2) are subjected to two-stage grinding and classification, with a grinding fineness of -325 mesh accounting for about 79%; the classification overflow is classified and deslimed to separate +20μm coarse slurry and -20μm fine slurry; wherein, the grinding concentration is 60%~75% and the classification concentration is 40%~50%; (4) Two-stage coarse flotation: Add 75 g / t of copper sulfate, 65 g / t of combined collector CR, and 4 g / t of frother 2# oil to the +20μm fine particle slurry obtained in step (3), and the slurry concentration is 25%~35% for two-stage roughing 1. Add 15 g / t of copper sulfate and 18 g / t of combined collector CR to the tailings of two-stage roughing 1 for two-stage roughing 2. After merging the froth from the two roughing stages, add 180 g / t of water glass for two cleaning stages. Return the middlings from the cleaning stages in sequence. The concentrate from two-stage cleaning stages 2 is gold concentrate 2. Add 10 g / t of combined activator AR and 10 g / t of combined collector CR to the tailings of two-stage roughing 2 for two-stage scavenging 1. Add 8 g / t of combined activator AR and CR to the tailings of two-stage scavenging 1. Two-stage scavenging (2) is carried out at 30g / t. The tailings from the two-stage scavenging are called tailings (1). The middlings from the two scavenging processes and the middlings from the cleaning process (1) are combined into middlings. The roughing, cleaning, and scavenging processes all use conventional aerated mechanical stirring flotation machines for low-turbulence separation. The impeller speed is controlled at 1000~1400r / min, the aeration rate is 0.8~1.4m³ / (m²·min), the inlet air pressure is >15kPa, the average diameter of the generated bubbles is 1~5mm, and the foam layer thickness is <10cm.

[0047] (5) Three-stage middlings regrinding: The middlings obtained in step (4) are regrinded and classified, and the overflow fineness of the classification is about 87% -400 mesh; the grinding concentration is 60%~75% and the classification concentration is 35%~50%.

[0048] (6) Three-stage fine-grained enhanced flotation: The graded overflow slurry obtained in step (5) and the -20μm fine-grained slurry obtained in step (3) are combined to form the fine-grained material to be processed; copper sulfate 20 g / t and combined collector CR 15 g / t are added to the fine-grained material for three-stage roughing; the concentrate from the three-stage roughing is directly subjected to three-stage cleaning; the foam from the cleaning is gold concentrate 3; copper sulfate 50 g / t and combined collector CR 20 g / t are added to the tailings from the three-stage roughing. The process involves three stages of scavenging, with the tailings from the scavenging being designated as Tailings 2. Both the tailings from the three stages of cleaning and the scavenging concentrate are returned to the roughing stage. Both the three stages of roughing and cleaning utilize microbubble flotation equipment, generating micron-sized bubbles with a diameter ≤0.5mm by adjusting the inlet and outlet pressures and air flow parameters, with -0.5mm bubbles accounting for ≥95%. The roughing parameters are: suction pump speed 600 r / min, aeration rate 0.85 m³ / (m²·h), circulation pressure 0.35 MPa, and pulp concentration 25%~35%. The cleaning parameters are: suction pump speed 700 r / min, aeration rate 0.28 m³ / (m²·h), circulation pressure 0.25 MPa, and pulp concentration 20%~25%. Scavenging uses conventional flotation equipment.

[0049] The results obtained were as follows: a gold concentrate (gold concentrate 1 + gold concentrate 2 + gold concentrate 3) with a yield of 5.30%, a gold grade of 30.57 g / t, and a gold recovery rate of 83.51% was obtained. Specific process parameters are shown in Table 3. Table 3: Process Indicators

[0050] The present invention has been described in detail above through specific and preferred embodiments. However, those skilled in the art should understand that the present invention is not limited to the embodiments described above. Any modifications, equivalent substitutions, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for cascaded sorting and enhanced recovery of fine-grained disseminated gold ore, characterized in that, Includes the following steps: (1) One-stage grinding and classification of raw ore: The raw ore is subjected to two-stage grinding and classification. The overflow fineness of the first-stage grinding and classification is -200 mesh, accounting for 45%~55%, and the overflow fineness of the second-stage grinding and classification is -325 mesh, accounting for 50%~65%. (2) First stage full-size flotation: Add combined activator AR, copper sulfate, combined collector CR and frother 2# oil to the two-stage grinding and classification overflow slurry obtained in step (1) to perform first stage roughing 1; add copper sulfate and combined collector CR to the tailings of first stage roughing 1 to perform first stage roughing 2; after merging the foam from the two roughing stages, add dispersant water glass to perform three stages of cleaning, and return the middlings in order. The foam from first stage cleaning 3 is gold concentrate 1, and the tailings from roughing 2 are the tailings from first stage flotation. (3) Two-stage grinding and classification: The first-stage flotation tailings obtained in step (2) are subjected to two-stage grinding and classification, with a grinding fineness of -325 mesh accounting for 75%~90%; the classification overflow is classified and deslimed to separate +20μm coarse slurry and -20μm fine slurry. (4) Two-stage coarse-grained flotation: Add copper sulfate, combined collector CR, and frother 2# oil to the +20μm coarse-grained slurry obtained in step (3) for two-stage roughing 1. Add copper sulfate and combined collector CR to the tailings of two-stage roughing 1 for two-stage roughing 2. After merging the foam from the two roughing stages, add water glass dispersant for two-stage cleaning. Return the middlings from the cleaning to the original order. The concentrate from the two-stage cleaning 2 is gold concentrate 2. Add combined activator AR and combined collector CR to the tailings of two-stage roughing 2 for two-stage scavenging 1. Add combined activator AR and combined collector CR to the tailings of two-stage scavenging 1 for two-stage scavenging 2. The tailings from the two-stage scavenging 2 are tailings 1. The foam from the two scavenging stages and the middlings from the cleaning 1 stage are merged into middlings. (5) Three-stage middlings regrinding: The middlings obtained in step (4) are regrinded and classified, with the overflow fineness of the classification being -400 mesh accounting for 80%~90%; (6) Three-stage fine-grained enhanced flotation: The graded overflow slurry obtained in step (5) and the -20μm fine-grained slurry obtained in step (3) are combined to form the fine-grained material to be processed; copper sulfate and combined collector CR are added to the fine-grained material to carry out three-stage roughing; the three-stage roughing concentrate is directly subjected to one cleaning, and the cleaning foam is gold concentrate 3; copper sulfate and combined collector CR are added to the three-stage roughing tailings to carry out one scavenging, and the scavenging tailings are tailings 2; the three-stage cleaning tailings and scavenging concentrate are returned to the roughing stage; among them, both roughing and cleaning adopt micron bubble flotation technology.

2. The method for cascaded sorting and enhanced recovery of fine-grained disseminated gold ore according to claim 1, characterized in that, The combined activator AR is a mixture of Na2CO3 and Na2S in a ratio of 30:1; the combined collector CR is a mixture of MA and BK721 in a ratio of 10:

1.

3. The method for cascaded sorting and enhanced recovery of fine-grained disseminated gold ore according to claim 1, characterized in that, The reagent regimes for each stage of flotation are as follows: In step (2), the first roughing stage 1 adds 300-600 g / t of combined activator AR, 50-150 g / t of copper sulfate, 120-300 g / t of combined collector CR, and 6 g / t of No. 2 oil; the second roughing stage adds 20-50 g / t of copper sulfate and 60-150 g / t of combined collector CR; and the first cleaning stage 1 adds 100-300 g / t of water glass. In step (4), copper sulfate 25~75 g / t, combined collector CR 30~75 g / t, and No. 2 oil 2~6 g / t are added to the second stage roughing 1; copper sulfate 10~20 g / t and combined collector CR 15~50 g / t are added to the second stage roughing 2; combined activator AR 5~15 g / t and combined collector CR 15~30 g / t are added to both the second stage scavenging 1 and the second stage scavenging 2; and water glass 0-200 g / t is added to the second stage roughing 1. In step (6), copper sulfate 10~20 g / t and combined collector CR 15~30 g / t are added for roughing; copper sulfate 20~50 g / t and combined collector CR 10~20 g / t are added for scavenging.

4. The method for cascaded sorting and enhanced recovery of fine-grained disseminated gold ore according to claim 1, characterized in that, In step (1), the grinding concentration of the two stages in the first stage is 60%~75%, and the classification concentration of the two stages is 40%~60%; in step (3), the grinding concentration of the second stage is 60%~75%, and the classification concentration is 40%~50%; in step (5), the middlings regrinding concentration of the third stage is 60%~75%, and the classification concentration is 35%~50%.

5. The method for cascaded sorting and enhanced recovery of fine-particle disseminated gold ore according to claim 1, characterized in that, The pulp concentration for roughing in steps (2) and (4) is 25% to 35%.

6. The method for cascaded sorting and enhanced recovery of fine-grained disseminated gold ore according to claim 1, characterized in that, In steps (2) and (4), all flotation processes were carried out using a conventional aerated mechanical stirring flotation machine for low-turbulence separation. The impeller speed was controlled at 1000~1400 r / min, the aeration rate was 0.8~1.4 m³ / (m²·min), the inlet air pressure was >15 kPa, the average diameter of the generated bubbles was 1~5 mm, and the foam layer thickness was <10 cm.

7. The method for cascaded sorting and enhanced recovery of fine-grained disseminated gold ore according to claim 1, characterized in that, The roughing and fine selection in step (6) uses a microbubble flotation device to generate micron-sized bubbles with a diameter ≤0.5mm by adjusting the inlet and outlet pressure and air volume parameters, of which -0.5mm bubbles account for ≥95%.

8. The method for cascaded sorting and enhanced recovery of fine-grained disseminated gold ore according to claim 7, characterized in that, The microbubble flotation equipment is selected from one of the following: a packed medium flotation column, a cyclone static flotation column, or a combined column-machine flotation machine.

9. The method for cascaded sorting and enhanced recovery of fine-grained disseminated gold ore according to claim 7, characterized in that, The parameters for roughing are: suction pump speed of 350~600 r / min, aeration rate of 0.45~0.85 m³ / (m²·h), circulation pressure of 0.15~0.35 MPa, and slurry concentration of 25%~35%; the parameters for cleaning are: suction pump speed of 450~700 r / min, aeration rate of 0.15~0.30 m³ / (m²·h), circulation pressure of 0.12~0.25 MPa, and slurry concentration of 20%~25%.

10. The method for cascaded sorting and enhanced recovery of fine-grained disseminated gold ore according to claim 7, characterized in that, Step (6) can be performed using conventional flotation equipment or microbubble flotation equipment.

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