A grinding-flotation method for a refractory low-grade gold ore

Abstract

The present application relates to a kind of low-grade gold ore of refractory grinding-flotation method, to solve the problem of low-grade gold ore of refractory low efficiency, poor quality.In the method, the coarse grinding link of innovation is added to the mill with special grinding aid, gold ore activator and gangue mineral inhibitor, which lays a good foundation for subsequent flotation operation.In the stage of concentration, the tailings of concentration are handled separately, and the inhibitor is added to the regrinding, and the regrinding process is accurately controlled, and then the tailings of concentration are reselected, to further improve the Au grade and recovery rate of gold ore.The present application fully considers the complex characteristics of low-grade gold ore of refractory, and effectively improves the dissociation degree of gold ore by optimizing grinding medium and reagent, improves the flotation index of Au, and realizes the efficient recovery of low-grade gold ore of refractory Au.

Description

Technical Field

[0001] This invention belongs to the field of gold ore beneficiation technology, specifically relating to a grinding-flotation method for difficult-to-process low-grade gold ore. Background Technology

[0002] Gold, as an important precious metal resource, plays a crucial role in global economic and industrial development. However, with the continuous mining and utilization of gold resources, easily beneficiated gold ore resources are gradually decreasing. Statistics show that nearly one-third of my country's gold resources are refractory ores, rich in impurities such as arsenic and carbon, or where gold is present as fine-grained inclusions. Conventional beneficiation methods can only achieve low gold recovery rates, resulting in resource waste.

[0003] These gold deposits often exhibit diverse mineral compositions and complex symbiotic relationships between gold minerals and other minerals. Gold exists as fine-grained inclusions within sulfide minerals, quartz, and other minerals, making its liberation exceptionally difficult. For example, in a gold mine in Qinghai, gold minerals are tightly encased within the crystal lattice of pyrite or arsenopyrite, making it difficult to fully expose them using conventional grinding methods, thus affecting gold recovery. Due to the fine particle size of gold, the requirements for the grinding process are quite stringent. Over-grinding not only increases energy consumption and costs but may also lead to over-crushing of minerals, thereby affecting subsequent flotation results and resulting in unsatisfactory beneficiation indicators. Therefore, it is urgent to solve the problem of over-grinding and ensure sufficient liberation of gold-bearing minerals to achieve a fineness suitable for flotation separation.

[0004] Traditional grinding media have also shown certain limitations in processing difficult-to-process low-grade gold ores. Common steel ball milling media may result in insufficient selective liberation of minerals during the grinding process, failing to specifically liberate gold minerals from their carrier minerals.

[0005] Flotation, a common method for gold ore beneficiation, faces numerous challenges when processing refractory, low-grade gold ores. These ores possess complex surface properties, often requiring specific flotation reagent regimes and process conditions for effective flotation. However, current flotation reagents often suffer from poor selectivity, high dosage, and high cost. Furthermore, the competitive adsorption of flotation reagents by impurity minerals potentially present in refractory, low-grade gold ores hinders the improvement of gold mineral flotation recovery rates.

[0006] Furthermore, the beneficiation process for difficult-to-process low-grade gold ores must also consider requirements related to environmental protection and comprehensive resource utilization. Traditional beneficiation processes may generate large amounts of tailings and wastewater, causing serious environmental pollution. At the same time, if the valuable metals remaining in the tailings cannot be effectively recovered and utilized, it will also result in resource waste.

[0007] Against this backdrop, developing an efficient, environmentally friendly, and economical grinding-flotation process for refractory low-grade gold ores has become an urgent need in the mineral processing field. Researchers are constantly exploring new grinding media, optimizing grinding process parameters, and improving flotation reagent regimes and process flows to enhance the beneficiation performance of refractory low-grade gold ores, thereby maximizing resource utilization and minimizing environmental impact. Summary of the Invention

[0008] The purpose of this invention is to overcome the shortcomings of the prior art and provide a grinding-flotation method for difficult-to-process low-grade gold ores.

[0009] The objective of this invention is achieved through the following technical solution: a grinding method for difficult-to-process low-grade gold ore, comprising the following steps:

[0010] Grinding aid, gold ore activator and gangue mineral inhibitor are added to the gold ore and then ground; wherein the grinding aid consists of grinding aid 1 and grinding aid 2, grinding aid 1 is graphene oxide and grinding aid 2 is sodium polyacrylate or isopentenyl alcohol polyoxyethylene ether.

[0011] Furthermore, the difficult-to-process low-grade gold ore has an Au grade of 1.8 g / t-2.5 g / t, an Al2O3 content of 55%-65%, a SiO2 content of 10%-20%, and more than 80% of the gold grains / gold-bearing minerals have an intercalation particle size of less than 20 micrometers.

[0012] Furthermore, the grinding aid 1 is used at a dosage of 1-5 g / t of raw ore, and the grinding aid 2 is used at a dosage of 50-100 g / t of raw ore.

[0013] Furthermore, the gold ore activator is sodium sulfide or copper sulfate, with a dosage of 180-400 g / t of raw ore; the gangue mineral inhibitor is xanthan gum, sodium phytate, or locust bean gum, with a dosage of 200-500 g / t of raw ore.

[0014] Furthermore, the grinding media used in the grinding process is hexagonal prism steel forging.

[0015] Furthermore, the diameter of the outer circle of the hexagonal prism steel forging end face × column height includes specifications of φ30×35mm, φ35×40mm and φ40×50mm, the mill is a conical mill, the filling rate is 30%-35%, the grinding concentration is 50-70%, and the grinding fineness is 65%-73%.

[0016] Preferably, the particle size of the ore after grinding should be within the range suitable for flotation.

[0017] The present invention also provides a flotation method for difficult-to-process low-grade gold ore, comprising the above-mentioned grinding method for difficult-to-process low-grade gold ore, and further comprising the following steps:

[0018] 1) Roughing: pH adjuster, collector and frother are added to the slurry obtained from grinding in sequence. After stirring and adjusting the slurry, roughing operation is carried out to obtain rough concentrate and rough tailings.

[0019] 2) Fine treatment: After adding inhibitors to the rough concentrate, fine treatment is carried out to obtain concentrate one and fine middlings;

[0020] 3) Scavenging: Add collector and frother to the roughing tailings for scavenging to obtain tailings 1;

[0021] 4) Regrinding and re-selection: The selected middlings are regrinded with the gangue mineral inhibitor, and then a collector and a frother are added for re-selection to obtain concentrate II and tailings II.

[0022] Furthermore, the pH adjuster is sodium carbonate or sodium hydroxide; the collector is composed of collector 1 and collector 2, collector 1 is ethyl xanthate, butyl xanthate or pentyl xanthate, and collector 2 is butylammonium black or ethyl thiocyanate; the foaming agent is pine oil or methyl isobutyl methanol.

[0023] Furthermore, in step 1), the amount of pH adjuster used in the roughing process is 1600-3000 g / t of raw ore, the amount of collector 1 and collector 2 is 80-150 g / t of raw ore and 40-80 g / t of raw ore, respectively, and the amount of frother is 20-30 g / t of raw ore.

[0024] In step 2), the selection is a blank selection;

[0025] In step 3), the dosage of collector 1 and collector 2 during scavenging is 60-120g / t of raw ore and 30-60g / t of raw ore, respectively, and the dosage of frother is 18-27g / t of raw ore.

[0026] In step 4), the amount of gangue mineral inhibitor used in the regrinding process is 10-20 g / t of raw ore; the amounts of collector 1 and collector 2 are 20-40 g / t of raw ore and 10-20 g / t of raw ore, respectively, and the amount of frother is 0-5 g / t of raw ore.

[0027] During roughing, a pH adjuster is used to regulate the pulp potential, and then ethyl xanthate (or butyl xanthate, pentyl xanthate) and butylammonium black (or ethyl thiocyanate) are added. Ethyl xanthate or butyl xanthate has good general collecting ability for sulfide minerals, while butylammonium black (or ethyl thiocyanate) has good selective collecting ability for gold-bearing minerals. The combination of the two can enhance the selective collecting ability for gold-bearing minerals through synergistic effect, and better achieve efficient recovery of gold-bearing minerals. During scavenging, the content of target minerals in the pulp is low, and they are mostly fine-grained gold-bearing minerals. Adding collectors in the scavenging stage is beneficial to the recovery of fine-grained gold-bearing minerals.

[0028] Furthermore, in step 2), the selection process is performed 3 times, namely selection 1, selection 2 and selection 3. The medium ore from selection 2 and selection 3 is returned to the previous operation in sequence, and the medium ore from selection 1 is selected medium ore.

[0029] In step 3), the scavenging is performed twice. The scavenged ore is returned to the previous operation in sequence, and the scavenged tailings are tailings 1'.

[0030] Preferably, the dosage of collector 1 and collector 2 in scavenging is 40-80g / t of raw ore and 20-40g / t of raw ore, respectively, and the dosage of frother is 10-15g / t of raw ore; the dosage of collector 1 and collector 2 in scavenging is 20-40g / t of raw ore and 10-20g / t of raw ore, respectively, and the dosage of frother is 8-12g / t of raw ore.

[0031] In step 4), the re-selection process is: one roughing, one cleaning, one scavenging, then the middlings of the cleaning, then the middlings of the scavenging returned to the roughing, then the cleaning concentrate is concentrate two, and then the tailings are scavenged and become tailings two.

[0032] Furthermore, in step 4), the gangue mineral inhibitor, collector, and frother are added during the roughing process.

[0033] Furthermore, in step 4), the grinding media used in the regrinding process are ceramic balls; the ceramic balls used include those with diameters of φ5mm, φ4mm, φ3mm, and φ2mm, the mill is an abrasive mill, the filling rate is 30%-35%, the grinding concentration is 50%-70%, and the grinding fineness is -0.074mm, accounting for 80%-85%.

[0034] The principle of this invention is as follows: During the grinding process of the raw ore, special grinding aids, gold ore activators, and gangue mineral inhibitors are added to increase the duration of action of the reagents and minerals; specific grinding media and equipment are used for grinding, with a conical mill paired with hexagonal steel forgings to improve over-grinding, increase grinding efficiency and uniformity, and enable the ore to quickly reach the required fineness; pH adjusters and collectors are added during roughing to achieve efficient recovery of gold-bearing minerals, and reagents are adjusted according to the characteristics of minerals at different stages during cleaning and scavenging to improve concentrate quality and recovery rate; middlings from the first cleaning stage are regrinded using an abrasive mill paired with ceramic ball media and inhibitors to improve mineral liberation; the middlings regrinding and re-selection process is adopted to adapt to situations with large middlings quantities and complex mineral compositions, optimize ore particle size distribution, and improve flotation efficiency and concentrate quality.

[0035] The beneficial effects of this invention are:

[0036] 1. This invention provides a grinding method for difficult-to-process low-grade gold ore. By simultaneously adding grinding aids, gold ore activators, and gangue mineral inhibitors during the grinding process of the raw ore, grinding efficiency can be improved, ensuring sufficient action time for the activators and inhibitors, thereby significantly improving mineral separation efficiency. Graphene oxide can penetrate into the cracks of ore particles. Utilizing its high specific surface area and excellent mechanical properties, it generates stress concentration within the ore particles, promoting crack propagation and extension, accelerating the crushing process of ore particles, and reducing grinding time and energy consumption. Isopentenyl alcohol polyoxyethylene ether and sodium polyacrylate, as grinding aids, can uniformly disperse cement particles and improve grinding efficiency. Gold ore activators can specifically activate target minerals, altering their surface properties and enhancing their affinity for specific collectors, thereby improving the floatability of target minerals in subsequent beneficiation processes. Inhibitors can selectively inhibit the activity of non-target minerals, reducing their floatability. In this way, target and non-target minerals can be separated more accurately, improving the efficiency and precision of mineral separation.

[0037] 2. The grinding method provided by this invention effectively improves the situation of over-grinding by using a conical mill with hexagonal prism steel forged media. Hexagonal prism steel forging has unique shape and physical properties, which can effectively improve grinding efficiency and uniformity during the grinding process. Compared with traditional steel balls, hexagonal prism steel forging has a larger contact area with the ore, resulting in stronger collision and friction, thus enabling the ore to reach the required fineness more quickly. This reduces wear and lowers production energy consumption.

[0038] 3. This invention provides a flotation method for difficult-to-select low-grade gold ore. Through precise reagent formulation and combination, it plays an optimal role in each stage of roughing, cleaning and scavenging, greatly improving the grade and recovery rate of gold concentrate. The middlings in the cleaning stage are regrinded and re-selected to fully recover the gold minerals in the middlings and improve the comprehensive utilization rate of gold ore resources.

[0039] 4. In the flotation method provided by this invention, middlings regrinding and re-concentration has good adaptability to difficult-to-process low-grade gold ores with large middlings and complex mineral composition, improving the versatility and stability of the process. Re-grinding is performed using an abrasive mill-ceramic ball media, with inhibitors added during the grinding process. Ceramic balls have advantages such as high hardness and good wear resistance, effectively improving the regrinding effect. Using an abrasive mill and adding inhibitors increases the contact opportunities between the inhibitors and minerals, making non-target minerals hydrophilic. This reduces wear and lowers production energy consumption. Attached Figure Description

[0040] Figure 1 This is a flowchart illustrating the principles of the present invention;

[0041] Figure 2 This is a schematic diagram of the hexagonal prism steel forging of the present invention;

[0042] Figure 3 A flowchart illustrating the Comparative Example 3 principle;

[0043] Figure 4 The flowchart for the Comparative Example 4 principle. Detailed Implementation

[0044] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings, but the scope of protection of the present invention is not limited to the following description.

[0045] Example 1

[0046] 1. Ore characteristics:

[0047] A certain arsenopyrite-type gold deposit in the Qaidam Basin of my country is characterized by complex mineral composition, fine-grained gold / gold-bearing minerals (over 80% of the gold / gold-bearing minerals have a grain size of less than 20 micrometers), and high clay mineral content. The raw ore has a gold grade of 2.15 g / t, which, although not high, meets the requirements for lode gold mining under current economic and technological conditions. The ore contains 59.70% SiO2 and 15.75% Al2O3, indicating a high content of quartz, silicates, and aluminosilicates. The ore also contains 0.32% As and 1.15% C, classifying it as a difficult-to-process, low-grade gold ore. Therefore, Au is the most important recoverable element from the raw ore. Currently, the grinding and classification processes and reagent systems in the beneficiation plant are inadequate, resulting in low gold concentrate grades and recovery rates.

[0048] 2. Mineral processing technology:

[0049] (1) The gold ore is ground. Grinding aid 1: 2 g / t graphene oxide, grinding aid 2: 80 g / t isopentenyl alcohol polyoxyethylene ether, activator: 200 g / t copper sulfate, inhibitor: 320 g / t sodium phytate. The grinding medium is hexagonal prism steel forging (see attached schematic diagram of hexagonal prism steel forging). Figure 2 The steel forgings used have outer diameter of circumscribed circle × column height of φ30×35mm, φ35×40mm, φ40×50mm, etc., in a ratio of 3:4:3. The mill is a conical mill with a filling rate of 30%, a grinding concentration of 67%, a grinding time of 11 minutes, and a grinding fineness of -0.074mm accounting for 70% (of which -0.026mm particle size accounts for 30% of the -0.074mm particle size, and +0.026-0.074mm accounts for 70% of the -0.074mm particle size).

[0050] (2) Add 2000g / t sodium carbonate as modifier, 100g / t butyl xanthate as collector 1, 50g / t butylammonium black powder as collector 2, and 24g / t methyl isobutyl methanol as frother. After adjusting the slurry, carry out flotation roughing to obtain roughing concentrate and roughing tailings.

[0051] (3) The rough concentrate is subjected to three fine-tuning processes to obtain concentrate one. All three fine-tuning processes are blank fine-tuning processes. The middlings of fine-tuning 1 are processed separately, while the middlings of fine-tuning 2 and fine-tuning 3 are returned to the previous level operation in sequence.

[0052] (4) Add collector 1 butyl xanthate 50g / t raw ore, collector 2 butylammonium black powder 30g / t raw ore, and frother methyl isobutyl methanol 12g / t raw ore to the roughing tailings for the first scavenging. Add collector 1 butyl xanthate 30g / t raw ore, collector 2 butylammonium xanthate 15g / t raw ore, and frother methyl isobutyl methanol 10g / t raw ore to the tailings for the second scavenging. Return the ore to the scavenging order. The scavenged tailings are tailings one.

[0053] (5) The selected intermediate ore is regrinded and re-selected. The dosage of sodium phytate inhibitor in the regrinding process is 10 g / t of raw ore; the grinding media is ceramic balls with diameters of φ5 mm, φ4 mm, φ3 mm, and φ2 mm in a ratio of 2:3:2:2; the mill is an alumina mill with a filling rate of 35%, a grinding concentration of 50%, a grinding time of 3 min, and a grinding fineness of -0.074 mm accounting for 82% (of which -0.026 mm particles account for 36% of the -0.074 mm particles, and +0.026-0.074 mm particles account for 64% of the -0.074 mm particles); after regrinding The middlings of the selected ore are then subjected to re-selection. The re-selection process consists of one roughing, one cleaning, and one scavenging. Reagents are added only during the roughing process of the re-selection. The collectors for the roughing process are butyl xanthate 1 and butylammonium black powder, respectively, at 20 g / t of raw ore and 10 g / t of raw ore. The frother methyl isobutyl methanol is used at 5 g / t of raw ore. No reagents are added during the cleaning and scavenging processes of the re-selection. The middlings from the cleaning process and the middlings from the re-selection and scavenging process are returned to the roughing process of the re-selection to obtain concentrate 2 and tailings 2. Concentrate 1 and concentrate 2 obtained in S4 are combined into the final concentrate. Tailings 1 and tailings 2 obtained in S5 are combined into the final tailings.

[0054] 3. Mineral processing test indicators:

[0055] Based on detailed condition tests, the grinding method of the raw ore was a conical mill-steel forging mill. Grinding aids, activators, and inhibitors were added during grinding. Based on the flotation process of "one roughing, two scavenging, and three cleaning", the middlings of the first cleaning were further processed by an abrasive mill-ceramic ball mill. The middlings of the first cleaning underwent "one roughing, one cleaning, and one scavenging". Finally, the flotation closed-circuit test obtained good technical indicators, and the results are shown in Table 1.

[0056] Table 1

[0057] Product Name Yield (%) Au grade (g / t) Au recovery rate (%) Concentrate 6.13 31.01 88.24 Tailings 93.87 0.27 11.76 raw ore 100.00 2.15 100.00

[0058] As shown in Table 1, the Au grade of the concentrate is 31.01 g / t, which is 14.39 times higher than that of the raw ore, and the recovery rate is as high as 88.24%.

[0059] Example 2

[0060] 1. The ore characteristics are the same as in Example 1, and the beneficiation process is as follows:

[0061] (1) The gold ore is ground. Grinding aid 1 graphene oxide 1.5g / t, grinding aid 2 sodium polyacrylate 90g / t, activator sodium sulfide 400g / t raw ore, and inhibitor locust bean gum 200g / t raw ore are added. The grinding media is hexagonal prism steel forging. The diameter of the outer circle of the end face of the steel forging × the column height is φ30×35mm, φ35×40mm, φ40×50mm, etc., with a ratio of 1:1:1. The mill is a conical mill with a filling rate of 33%, a grinding concentration of 60%, a grinding time of 10min, and a grinding fineness of -0.074mm accounting for 68% (of which -0.026mm particle size accounts for 28% of the -0.074mm particle size, and +0.026-0.074mm accounts for 72% of the -0.074mm particle size).

[0062] (2) Add 2200g / t sodium carbonate as modifier, 120g / t pentyl xanthate as collector 1, 50g / t butylammonium black powder as collector 2, and 24g / t pine oil as collector 2. After adjusting the slurry, carry out flotation roughing to obtain roughing concentrate and roughing tailings.

[0063] (3) The rough concentrate is subjected to three fine-tuning processes to obtain concentrate one. The three fine-tuning processes are blank fine-tuning processes. The middlings of fine-tuning 1 are processed separately, and the middlings of fine-tuning 2 and fine-tuning 3 are returned to the previous level operation in sequence.

[0064] (4) Collector 1 pentyl xanthate 60g / t raw ore, collector 2 butyl xanthate 30g / t raw ore, frother pine oil 10g / t raw ore are added to the roughing tailings for the first scavenging. Collector 1 pentyl xanthate 30g / t raw ore, collector 2 butyl xanthate 10g / t raw ore, frother pine oil 8g / t raw ore are added to the tailings of the first scavenging for the second scavenging. The ore sequence of the scavenged tailings is returned, and the scavenged tailings are tailings one.

[0065] (5) The selected medium ore is regrinded and re-selected. The dosage of locust bean gum inhibitor in the regrinding process is 10g / t of raw ore; the grinding media is ceramic balls with diameters of φ5mm, φ4mm, φ3mm, and φ2mm in a ratio of 1:1:1:1; the mill is an agar mill with a filling rate of 33%, a grinding concentration of 50%, a grinding time of 3min30s, and a grinding fineness of -0.074mm accounting for 85% (of which, -0.026mm particles account for 38% of the -0.074mm particles, and +0.026-0.074mm particles account for 62% of the -0.074mm particles). The middlings from the regrinding process are then subjected to further re-selection. The re-selection process consists of one roughing, one cleaning, and one scavenging process. Reagents are added only during the roughing process of the re-selection. The re-selection collectors are 24 g / t raw ore and 10 g / t raw ore, respectively, and the frother is 5 g / t raw ore. No reagents are added during the cleaning and scavenging processes of the re-selection. The middlings from the cleaning process and the middlings from the re-selection and scavenging process are returned to the roughing process of the re-selection process to obtain concentrate 2 and tailings 2. Concentrate 1 and concentrate 2 obtained in S4 are combined into the final concentrate, and tailings 1 and tailings 2 obtained in S5 are combined into the final tailings.

[0066] 3. Mineral processing test indicators:

[0067] Based on detailed condition tests, activators and inhibitors were added to the grinding process. The grinding method for the raw ore was a conical mill-steel forging mill. Based on the flotation process of "one roughing, two scavenging, and three cleaning", the middlings of the first cleaning were further processed by an abrasive mill-ceramic ball mill. The middlings of the first cleaning underwent "one roughing, one cleaning, and one scavenging". Finally, the flotation closed-circuit test obtained good technical indicators, and the results are shown in Table 2.

[0068] Table 2

[0069] Product Name Yield (%) Au grade (g / t) Au recovery rate (%) Concentrate 6.30 30.08 88.22 Tailings 93.70 0.27 11.78 raw ore 100.00 2.15 100.00

[0070] As shown in Table 2, the Au grade of the concentrate was 30.08 g / t, which was 14.00 times higher than that of the raw ore, with a recovery rate as high as 88.22%. By changing the grinding parameters and the type and amount of beneficiation reagents, this grinding-flotation process also recovered Au from the ore quite well.

[0071] Example 3

[0072] 1. The ore characteristics are the same as in Example 1, and the beneficiation process is as follows:

[0073] (1) The gold ore is ground. Grinding aid 1 graphene oxide 1g / t and grinding aid 2 isopentenyl alcohol polyoxyethylene ether 100g / t are added. The grinding media is hexagonal prism steel forging. The diameter of the outer circle of the end face of the steel forging × the column height is φ30×35mm, φ35×40mm, φ40×50mm, etc., with a ratio of 1:2:1. The mill is a conical mill with a filling rate of 35%, a grinding concentration of 50%, a grinding time of 10min30s, and a grinding fineness of -0.074mm accounting for 73% (of which, -0.026mm particle size accounts for 33% of the -0.074mm particle size, and +0.026-0.074mm accounts for 67% of the -0.074mm particle size).

[0074] (2) Add 2200g / t of sodium hydroxide as a modifier, 120g / t of ethyl xanthate as a collector, 60g / t of ethyl thiocyanate as a collector, and 20g / t of methyl isobutyl methanol as a collector. After adjusting the slurry, carry out flotation roughing to obtain roughing concentrate and roughing tailings.

[0075] (3) The rough concentrate is subjected to three fine-tuning processes to obtain concentrate one. All three fine-tuning processes are blank fine-tuning processes. The middlings of fine-tuning 1 are processed separately, while the middlings of fine-tuning 2 and fine-tuning 3 are returned to the previous level operation in sequence.

[0076] (4) Add 50g / t of collector 1 ethyl xanthate, 30g / t of collector 2 ethyl thiocyanate, and 12g / t of frother methyl isobutyl methanol to the roughing tailings for the first scavenging. Add 30g / t of collector 1 ethyl xanthate, 10g / t of collector 2 ethyl thiocyanate, and 10g / t of frother methyl isobutyl methanol to the tailings from the first scavenging for the second scavenging. Return the scavenged tailings in the correct order. The scavenged tailings are called tailings one.

[0077] (5) The selected medium ore is regrinded and re-selected. During regrinding, 20 g / t of xanthan gum inhibitor is added to the raw ore; the grinding media are ceramic balls with diameters of φ5 mm, φ4 mm, φ3 mm, and φ2 mm in a ratio of 1:2:2:1; the mill is an alumina mill with a filling rate of 35%, a grinding concentration of 60%, a grinding time of 2 min 30 s, and a grinding fineness of -0.074 mm accounting for 80% (of which -0.026 mm particles account for 34% of the -0.074 mm particles, and +0.026-0.074 mm particles account for 66% of the -0.074 mm particles); after regrinding... The middlings of the selected ore are then subjected to re-selection. The re-selection process consists of one roughing, one cleaning, and one scavenging. Reagents are added only during the roughing process of the re-selection. The collectors for the roughing process are ethyl xanthate 1 and ethyl thiocyanate 2 at 24 g / t of raw ore and 12 g / t of raw ore, respectively. The frother methyl isobutyl methanol is used at 5 g / t of raw ore. No reagents are added during the cleaning and scavenging processes of the re-selection. The middlings from the cleaning process and the middlings from the scavenging process are returned to the roughing process of the re-selection to obtain concentrate 2 and tailings 2. Concentrate 1 and concentrate 2 obtained in S4 are combined into the final concentrate. Tailings 1 and tailings 2 obtained in S5 are combined into the final tailings.

[0078] 3. Mineral processing test indicators:

[0079] Based on detailed condition tests, activators and inhibitors were added to the grinding process. The grinding method for the raw ore was a conical mill-steel forging mill. Based on the flotation process of "one roughing, two scavenging, and three cleaning", the middlings of the first cleaning were further processed by an abrasive mill-ceramic ball mill. The middlings of the first cleaning underwent "one roughing, one cleaning, and one scavenging". Finally, the flotation closed-circuit test obtained good technical indicators, and the results are shown in Table 3.

[0080] Table 3

[0081] Product Name Yield (%) Au grade (g / t) Au recovery rate (%) Concentrate 6.09 30.94 87.75 Tailings 93.91 0.28 12.25 raw ore 100.00 2.15 100.00

[0082] As shown in Table 3, the Au grade of the concentrate was 30.94 g / t, which was 14.41 times higher than that of the raw ore, with a recovery rate as high as 87.75%. By changing the grinding parameters and the type and amount of flotation reagents, this grinding-flotation process also recovered Au from the ore quite well.

[0083] Comparative Example 1

[0084] Comparative Example 1 used the same raw ore as Example 1, but changed the grinding method to a traditional conical mill-ball mill. The ratio of steel balls with diameters of φ30mm, φ35mm, and φ40mm was 3:4:3, the filling rate was 30%, the grinding concentration was 67%, the grinding time was 14 minutes, and the grinding fineness was -0.074mm, accounting for 70%. However, the -0.026mm particle size accounted for 40% of the -0.074mm particle size, indicating a serious over-grinding phenomenon. Grinding aids 1 (graphene oxide and isopentenyl alcohol polyoxyethylene ether), roughing activator (copper sulfate), and inhibitor (sodium phytate) were not added to the grinding process. The first two were added before the pH adjuster, and the latter two were added after the pH adjuster. The re-grinding and re-selection process of the middlings was the same as in Example 1. The types and dosages of various beneficiation reagents were the same as in Example 1.

[0085] Mineral processing test indicators:

[0086] Table 4

[0087] Product Name Yield (%) Au grade (g / t) Au recovery rate (%) Concentrate 7.55 23.35 81.95 Tailings 92.45 0.42 18.05 raw ore 100.00 2.15 100.00

[0088] Compared to Example 1, the grinding method in Comparative Example 1 significantly over-grinds the ore. The kinetic behavior of some gold-bearing sulfide ores during flotation differs from that of larger gold particles; their momentum is low, making it difficult to overcome the energy barrier between the ore particles and air bubbles, thus preventing them from adhering to the bubbles and hindering recovery. Comparing the results in Tables 1 and 4, it is clear that the Au grade and Au recovery rate in Comparative Example 1 are lower than those in Example 1, with the Au recovery rate being 6.26 percentage points lower. This clearly highlights the significant effect of adding grinding aids, activators, and inhibitors during the grinding process of the raw ore in Example 1, combined with hexagonal prism steel forging grinding.

[0089] Comparative Example 2

[0090] Comparative Example 2 used the same raw ore as Example 1, the only difference being that no grinding aid was added during the grinding process, the grinding time was 13 minutes, the grinding fineness was -0.074 mm with 70% of the particles being ground, and other conditions were the same as in Example 1.

[0091] Mineral processing test indicators:

[0092] Table 5

[0093] Product Name Yield (%) Au grade (g / t) Au recovery rate (%) Concentrate 5.85 30.00 81.61 Tailings 94.15 0.42 18.39 raw ore 100.00 2.15 100.00

[0094] Comparing Example 1 and Comparative Example 2, it can be seen that, at the same grinding fineness, the grinding time in Example 1 with the addition of grinding aid was 11 minutes, while the grinding time in Comparative Example 2 without the addition of grinding aid was 13 minutes. This indicates that the grinding aid has the effect of reducing grinding time and energy consumption. The Au grade and Au recovery rate of Comparative Example 2 were both lower than those of Example 1, with the Au recovery rate being 6.62 percentage points lower. This further demonstrates that the grinding aid in this invention plays a role in improving grinding efficiency, ensuring the effects of activator and inhibitor, thereby improving the Au grade and yield, while also reducing grinding time and energy consumption.

[0095] Comparative Example 3

[0096] Comparative Example 3 used the same raw ore as Example 1, with the same grinding method and flotation reagent system; however, the treatment of the middlings from the concentrate in Example 1 was changed, and the middlings from the concentrate were returned to the rougher, i.e., no regrinding-reflotation was performed. The flotation process is shown in the attached figure. Figure 3 The reagent dosing system for the remaining flotation operations is the same as in Example 1. The tailings from the second scavenging operation are the final tailings, and the final concentrate from the third cleaning operation are the final concentrate.

[0097] Mineral processing test indicators:

[0098] Table 6

[0099] Product Name Yield (%) Au grade (g / t) Au recovery rate (%) Concentrate 6.21 27.89 80.76 Tailings 93.79 0.44 19.24 raw ore 100.00 2.14 100.00

[0100] Comparing the results in Tables 1 and 6, it can be seen that the Au grade and Au recovery rate of Comparative Example 1 are not as good as those of Example 1, with the Au recovery rate being 7.48 percentage points lower. This fully highlights the significant effect of adding inhibitors to the selected middlings ore for regrinding and re-selection in Example 1.

[0101] Comparative Example 4

[0102] Comparative Example 4 used the same raw ore as Example 1, but changed the grinding method from Example 1 to a traditional conical mill-ball mill. The ratio of steel balls with diameters of φ30mm, φ35mm, and φ40mm was 3:4:3, the filling rate was 30%, the grinding concentration was 67%, the grinding time was 14 minutes, and the grinding fineness was -0.074mm, accounting for 70%. However, -0.026mm particles accounted for 40% of the -0.074mm particles, indicating severe over-grinding. Grinding aids 1 (graphene oxide and isopentenyl alcohol polyoxyethylene ether), roughing activator (copper sulfate), and inhibitor (sodium phytate) were not added to the grinding process. The first two were added before the pH adjuster, and the latter two were added after the pH adjuster. Furthermore, the treatment method of the middlings from the first stage of the concentrate was changed; the middlings were returned to the rougher stage, i.e., no regrinding-reflotation was performed. The flotation process is shown in the attached figure. Figure 4 The dosages of the remaining flotation reagents are the same as in Example 1. The tailings from the second scavenging operation are the final tailings, and the third cleaning operation is the final concentrate.

[0103] Mineral processing test indicators: Table 7

[0104] Product Name Yield (%) Au grade (g / t) Au recovery rate (%) Concentrate 5.68 29.88 78.94 Tailings 94.32 0.48 21.06 raw ore 100.00 2.15 100.00

[0105] Comparing the results in Tables 1 and 7, it can be seen that the Au recovery rate of Comparative Example 4 is far lower than that of Example 1, with a Au recovery rate 9.29 percentage points lower. This fully highlights the significant effect of adding grinding aids, activators, and inhibitors to the hexagonal prism steel forging mill in Example 1, and the use of a sand mill-ceramic balls with inhibitors for re-grinding and re-selection of the middlings ore.

[0106] The above description is merely a preferred embodiment of the present invention. It should be understood that the present invention is not limited to the forms disclosed herein and should not be construed as excluding other embodiments. It can be used in various other combinations, modifications, and environments, and can be altered within the scope of the concept described herein through the above teachings or related technologies or knowledge. Modifications and variations made by those skilled in the art that do not depart from the spirit and scope of the present invention should be within the protection scope of the appended claims.

Claims

1. A grinding method for refractory low-grade gold ore, wherein the refractory low-grade gold ore has an Au grade of 1.8 g / t-2.5 g / t, an Al2O3 content of 55%-65%, a SiO2 content of 10%-20%, and more than 80% of the gold grains / gold-bearing minerals have an embedded particle size of less than 20 micrometers, characterized in that, Includes the following steps: Grinding aid, gold ore activator, and gangue mineral inhibitor are added to the raw gold ore and then ground. The grinding aid consists of grinding aid 1 and grinding aid 2, where grinding aid 1 is graphene oxide and grinding aid 2 is sodium polyacrylate or isopentenyl alcohol polyoxyethylene ether. The gold ore activator is sodium sulfide or copper sulfate, and the dosage is 180-400 g / t of raw ore. The gangue mineral inhibitor is xanthan gum, sodium phytate, or locust bean gum, and the dosage is 200-500 g / t of raw ore.

2. The grinding method for difficult-to-process low-grade gold ore according to claim 1, characterized in that, The grinding aid 1 is used at a dosage of 1-5 g / t of raw ore, and the grinding aid 2 is used at a dosage of 50-100 g / t of raw ore.

3. A grinding method for refractory low-grade gold ore according to any one of claims 1-2, characterized in that, The grinding media used in the grinding process are hexagonal prism steel forgings.

4. The grinding method for a difficult-to-process low-grade gold ore according to claim 3, characterized in that, The diameter of the outer circle of the hexagonal prism steel forging end face × column height includes specifications of φ30×35mm, φ35×40mm and φ40×50mm. The mill is a conical mill with a filling rate of 30%-35%, a grinding concentration of 50-70%, and a grinding fineness of -0.074mm accounting for 65%-73%.

5. A flotation method for difficult-to-process low-grade gold ore, characterized in that, The grinding method for a difficult-to-process low-grade gold ore as described in any one of claims 1-4 further includes the following steps: 1) Roughing: pH adjuster, collector and frother are added to the slurry obtained from grinding in sequence. After stirring and adjusting the slurry, roughing operation is carried out to obtain roughing concentrate and roughing tailings. 2) Fine treatment: After adding inhibitors to the rough concentrate, fine treatment is carried out to obtain concentrate one and fine middlings; 3) Scavenging: Add collector and frother to the roughing tailings for scavenging to obtain tailings 1; 4) Regrinding and re-selection: The selected middlings are regrinded with the gangue mineral inhibitor, and then a collector and a frother are added for re-selection to obtain concentrate II and tailings II.

6. The flotation method for difficult-to-process low-grade gold ore according to claim 5, characterized in that, The pH adjuster is sodium carbonate or sodium hydroxide; the collector is composed of collector 1 and collector 2, collector 1 is ethyl xanthate, butyl xanthate or pentyl xanthate, and collector 2 is butylammonium black or ethyl thiocyanate; the foaming agent is pine oil or methyl isobutyl methanol.

7. The flotation method for difficult-to-process low-grade gold ore according to claim 6, characterized in that, In step 1), the amount of pH adjuster used in roughing is 1600-3000 g / t of raw ore, the amount of collector 1 and collector 2 is 80-150 g / t of raw ore and 40-80 g / t of raw ore, respectively, and the amount of frother is 20-30 g / t of raw ore. In step 2), the selection is a blank selection; In step 3), the dosage of collector 1 and collector 2 during scavenging is 60-120g / t of raw ore and 30-60g / t of raw ore, respectively, and the dosage of frother is 18-27g / t of raw ore. In step 4), the amount of gangue mineral inhibitor used in the regrinding process is 10-20 g / t of raw ore; the amounts of collector 1 and collector 2 are 20-40 g / t of raw ore and 10-20 g / t of raw ore, respectively, and the amount of frother is 0-5 g / t of raw ore.

8. The flotation method for difficult-to-process low-grade gold ore according to claim 5, characterized in that, In step 2), the selection process is performed 3 times, namely selection 1, selection 2 and selection 3. The medium ore from selection 2 and selection 3 is returned to the previous operation in sequence, and the medium ore from selection 1 is selected medium ore. In step 3), the scavenging is performed twice, and the ore is returned to the previous operation in the scavenging sequence. The scavenged tailings are tailings one. In step 4), the re-selection process is as follows: one roughing, one cleaning, one scavenging, then the middlings of the cleaning, then the middlings of the scavenging returned to the roughing, then the cleaning concentrate is concentrate two, and then the tailings are scavenged to tailings two.

9. The flotation method for difficult-to-process low-grade gold ore according to claim 5, characterized in that, In step 4), the grinding media used in the regrinding process are ceramic balls; the ceramic balls used include diameters of φ5mm, φ4mm, φ3mm and φ2mm, the mill is an abrasive mill, the filling rate is 30%-35%, the grinding concentration is 50%-70%, and the grinding fineness is -0.074mm, accounting for 80%-85%.

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