Ore grinding-flotation method for refractory low-grade gold ore

Abstract

The invention relates to an ore grinding-flotation method for refractory low-grade gold ore, and aims to solve the problems that the refractory low-grade gold ore is low in ore dressing efficiency and poor in quality. In the method, hexagonal prism steel forgings are innovatively adopted in the roughing and grinding link, a special grinding aid, a gold ore activating agent and a gangue mineral inhibitor are added into a grinding machine, and a good foundation is laid for subsequent flotation operation. And in the concentration stage, the concentration tailings are independently treated, regrinding is conducted by adding an inhibitor, the regrinding process is precisely controlled, then the concentration tailings are subjected to re-concentration operation, and the Au grade and the recovery rate of the gold ore are further improved. According to the method, the complex characteristics of the refractory low-grade gold ore are fully considered, the dissociation degree of the gold ore is effectively improved by optimizing the ore grinding medium and the reagent, the flotation index of Au is improved, and efficient recovery of Au in the refractory low-grade gold ore is achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of gold ore dressing, and in particular relates to a grinding-flotation method for difficult-to-select low-grade gold ore. Background Art

[0002] As an important precious metal resource, gold mines play a pivotal role in the global economic and industrial development. However, with the continuous mining and utilization of gold resources, the easily selectable gold resources are gradually decreasing. According to statistics, nearly 1 / 3 of my country's gold resources belong to the type of refractory ore, rich in impurities such as arsenic and carbon, or gold ores with fine inclusions. Conventional beneficiation methods can only obtain a low gold recovery rate, resulting in a waste of resources.

[0003] These gold mines often have diverse mineral compositions, and the symbiotic relationship between gold minerals and other minerals is complex. Gold exists in the form of fine-grained inclusions in sulfide ores, quartz and other minerals, making the dissociation of gold extremely difficult. For example, in a gold mine in Qinghai, gold minerals are tightly wrapped in the crystal lattice of pyrite or arsenopyrite, and conventional grinding methods are difficult to fully expose them, thus affecting the recovery of gold. Due to the fine particle size of gold embedding, the requirements for the grinding process are relatively harsh. Excessive grinding will not only increase energy consumption and costs, but may also lead to over-crushing of minerals, thereby affecting the subsequent flotation effect and resulting in unsatisfactory mineral processing indicators. Therefore, it is urgent to solve the problem of excessive grinding and ensure that the gold-containing minerals are fully dissociated to achieve a fineness suitable for flotation separation.

[0004] Traditional grinding media also show certain limitations when processing difficult-to-select low-grade gold ores. Common steel ball grinding media may cause insufficient selective dissociation of minerals during the grinding process, and cannot specifically dissociate gold minerals from their carrier minerals.

[0005] As a common method for gold ore beneficiation, flotation technology also faces many problems when dealing with difficult-to-select low-grade gold ores. The surface properties of difficult-to-select low-grade gold ores are complex, and often require specific flotation reagent systems and process conditions to achieve effective flotation. However, current flotation reagents often have problems such as poor selectivity, large dosage, and high cost. Moreover, due to the competitive adsorption of impurity minerals that may exist in difficult-to-select low-grade gold ores on flotation reagents, it is difficult to improve the flotation recovery rate of gold minerals.

[0006] In addition, the beneficiation process of difficult-to-benefit low-grade gold ores also needs to consider the requirements of environmental protection and comprehensive resource utilization. Traditional beneficiation processes may produce a large amount of tailings and wastewater, causing serious environmental pollution. At the same time, if the valuable metals remaining in the tailings cannot be effectively recycled, it will also cause a waste of resources.

[0007] In this context, the development of an efficient, environmentally friendly and economical grinding-flotation process for difficult-to-select low-grade gold ores has become an urgent need in the field of mineral processing. Researchers are constantly exploring new grinding media, optimizing grinding process parameters, and improving flotation reagent systems and process flows to improve the mineral processing indicators of difficult-to-select low-grade gold ores, maximize resource utilization and minimize environmental impact. Summary of the invention

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

[0009] The object of the present invention is achieved through the following technical scheme: A grinding method for difficult-to-select low-grade gold ore, comprising the following steps:

[0010] Grinding aids, gold ore activators and gangue mineral inhibitors are added to the gold ore and ground; wherein the grinding aids are composed of grinding aids 1 and 2, grinding aid 1 is graphene oxide, and grinding aid 2 is sodium polyacrylate or isopentanol polyoxyethylene ether.

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

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

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

[0014] Furthermore, the grinding medium used in the grinding is hexagonal steel forging.

[0015] Furthermore, the diameter of the circumscribed circle of the hexagonal steel forging end face × the column height include 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 treatment is within a range suitable for flotation.

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

[0018] 1) Roughing: pH adjuster, collector and frother are added to the flotation slurry obtained by grinding in sequence, and the slurry is stirred and adjusted before roughing to obtain roughing concentrate and roughing tailings;

[0019] 2) Concentration: adding an inhibitor to the rougher concentrate and then concentrating it to obtain concentrate 1 and concentrating middlings;

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

[0021] 4) Regrinding and reselection: adding the gangue mineral inhibitor to the selected middling ore for regrinding treatment, and then adding a collector and a frother for reselection to obtain a second concentrate and a second tailing.

[0022] Furthermore, it is 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 amyl xanthate, and collector 2 is butyl ammonium black medicine or ethylthiocarbamate; the foaming agent is pine oil or methyl isobutyl carbinol.

[0023] Further, in step 1), the amount of pH adjuster used in the roughing is 1600-3000 g / t of raw ore, the amounts of collector 1 and collector 2 are 80-150 g / t of raw ore and 40-80 g / t of raw ore respectively, and the amount of foaming agent is 20-30 g / t of raw ore;

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

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

[0026] In step 4), the amount of gangue mineral inhibitor used in the regrinding treatment 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 adjust the pulp potential, and then ethyl xanthate (or butyl xanthate, amyl xanthate) and butyl ammonium black medicine (or ethylthiocarbamate) are added. Ethyl xanthate or butyl xanthate has a good universal capture ability for sulfide minerals, while butyl ammonium black medicine (or ethylthiocarbamate) has a good selective capture ability for gold-bearing minerals. The combination of the two can enhance the selective capture ability for gold-bearing minerals through synergistic effect, and better realize the efficient recovery of gold-bearing minerals; during scavenging, the content of target minerals in the pulp is low, and most of them are relatively 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 number of times of the selection is 3, namely selection 1, selection 2 and selection 3, the intermediate ore of selection 2 and selection 3 is returned to the previous level of operation in sequence, and the intermediate ore of selection 1 is the selected intermediate ore;

[0029] In step 3), the number of sweeping is 2 times, and the sweeping tailings are returned to the previous level of operation in sequence, and the sweeping tailings are tailings one.

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

[0031] In step 4), the reselection process is one roughing selection, one concentrating selection, and one scavenging selection. The concentrating middlings are reselected, the scavenging middlings are reselected and returned to the roughing selection. The concentrating concentrate is the second concentrate, and the scavenging tailings are the second tailings.

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

[0033] Furthermore, in step 4), the grinding medium during the regrinding process is ceramic balls; the ceramic balls used include diameters of φ5mm, φ4mm, φ3mm, and φ2mm, the mill is an argon sand 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 the present invention is as follows: in the process of grinding the raw ore, special grinding aids, gold ore activators and gangue mineral inhibitors are added to increase the action time of the agents and minerals; specific grinding media and equipment are used for grinding, and a conical mill is matched with a hexagonal steel forging to improve over-crushing of the grinding, improve 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 during fine selection and scavenging, the agents are adjusted according to the characteristics of the minerals at different stages to improve the quality and recovery rate of the concentrate; the selected 1 intermediate ore is re-grinded using an argon sand mill with a ceramic ball medium and inhibitors are added to improve the mineral dissociation degree; a medium ore re-grinding and re-selection process is adopted to adapt to the situation of large amount of intermediate ore and complex mineral composition, optimize the ore particle size distribution, and improve the flotation efficiency and concentrate quality.

[0035] The beneficial effects of the present invention are:

[0036] 1. The present invention provides a grinding method for a difficult-to-select low-grade gold ore. By simultaneously adding a grinding aid, a gold ore activator and a gangue mineral inhibitor during the grinding process of the raw ore, the grinding efficiency can be improved, and the activator and the inhibitor can be guaranteed to have sufficient action time, thereby significantly improving the efficiency of mineral sorting. Graphene oxide can penetrate into the cracks of ore particles, and by utilizing its high specific surface area and excellent mechanical properties, stress concentration is generated inside the ore particles, promoting the expansion and extension of cracks, accelerating the crushing process of ore particles, and reducing grinding time and energy consumption; isopentanol polyoxyethylene ether and sodium polyacrylate as grinding aids can make cement particles evenly dispersed and improve grinding efficiency. The gold ore activator can activate the target mineral in a targeted manner, change its surface properties, enhance its affinity with a specific collector, and thus improve the floatability of the target mineral in the subsequent sorting process. The inhibitor can selectively inhibit the activity of non-target minerals and reduce their floatability. In this way, the target mineral and non-target mineral can be separated more accurately, and the efficiency and accuracy of mineral sorting can be improved.

[0037] 2. In the grinding method provided by the present invention, the over-crushing of the grinding is effectively improved by using a conical mill-hexagonal steel forging medium for grinding. The hexagonal steel forging has a unique shape and physical properties, which can effectively improve the grinding efficiency and uniformity during the grinding process. Compared with traditional steel balls, the hexagonal steel forging has a larger contact area with the ore, and the collision and friction are stronger, so that the ore can reach the required fineness more quickly. Reduce wear and reduce production energy consumption.

[0038] 3. The present invention provides a flotation method for difficult-to-select low-grade gold ores. Through precise reagent system and combination, it plays the best role in each stage of roughing, concentrating and scavenging, greatly improving the grade and recovery rate of gold concentrate; concentrating the middling ore, re-grinding and re-selecting it, fully recovering the gold minerals in the middling ore, and improving the comprehensive utilization rate of gold mine resources.

[0039] 4. In the flotation method provided by the present invention, the re-grinding and re-selection of middlings has good adaptability to low-grade gold ores with large amounts of middlings and complex mineral compositions, which are difficult to select, and improves the versatility and stability of the process. The regrinding is performed using the medium of the sand mill-ceramic ball, and inhibitors are added during the grinding process. Ceramic balls have the advantages of high hardness and good wear resistance, and can effectively improve the effect of regrinding. Using the sand mill-ceramic grinding and adding inhibitors is conducive to increasing the contact opportunity between the inhibitor and the mineral, making the non-target mineral hydrophilic. Reduce wear and reduce production energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 It is a flow chart of the principle of the present invention;

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

[0042] Figure 3 This is the principle flow chart of comparative example 3;

[0043] Figure 4 This is a principle flow chart of Comparative Example 4. DETAILED DESCRIPTION

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

[0045] Example 1

[0046] 1. Ore characteristics:

[0047] A certain arsenopyrite-type gold mine in the Qaidam Basin of my country has unfavorable characteristics such as complex mineral composition, fine distribution of gold particles / gold-bearing minerals (more than 80% of the gold particles / gold-bearing minerals have a distribution size of less than 20 microns), and high clay mineral content. The grade of the original ore gold is 2.15g / t. Although the grade is not high, it meets the requirements for the mining of rock gold under the current economic and technical conditions; the SiO2 content in the ore is 59.70%, and the Al2O3 content is 15.75%, indicating that the ore contains high content of quartz, silicate, and aluminosilicate minerals. The As content in the ore is 0.32%, and the C content is 1.15%, which is a difficult-to-select low-grade gold ore. Therefore, the Au element is the most important recovery element in the original ore. At present, the grinding and grading process and reagent system of the ore dressing plant are not suitable, and the grade and recovery rate of the gold concentrate are low.

[0048] 2. Ore dressing process:

[0049] (1) The gold ore was ground, and grinding aid 1 graphene oxide 2g / t ore, grinding aid 2 isopentanol polyoxyethylene ether 80g / t ore, activator copper sulfate 200g / t ore, inhibitor sodium phytate 320g / t ore were added to the grinding medium. The grinding medium was hexagonal steel forging (the schematic diagram of the hexagonal steel forging is shown in the attached figure). Figure 2 ), the specifications of the steel forging end face circumscribed circle diameter × column height are φ30×35mm, φ35×40mm, φ40×50mm, etc., with a ratio of 3:4:3, the mill is a conical mill, the filling rate is 30%, the grinding concentration is 67%, the grinding time is 11min, and the grinding fineness is -0.074mm, accounting for 70% (among which, -0.026mm particle size accounts for 30% of -0.074mm particle size, and +0.026-0.074mm accounts for 70% of -0.074mm particle size).

[0050] (2) adding 2000 g / t of sodium carbonate as an adjusting agent, 100 g / t of ore as a collector 1-butyl xanthate, 50 g / t of ore as a collector 2-butyl ammonium black powder, and 24 g / t of frother methyl isobutyl carbinol as an ore, and performing flotation roughing after slurry adjustment to obtain roughing concentrate and roughing tailings.

[0051] (3) The rough concentrate is subjected to three rounds of concentration to obtain concentrate 1. All three rounds of concentration are blank concentrations. The middlings from concentration 1 are processed separately, and the middlings from concentrations 2 and 3 are returned to the previous level of operation in sequence.

[0052] (4) Collector 1 butyl xanthate 50 g / t original ore, collector 2 butyl ammonium xanthate 30 g / t original ore, and foaming agent methyl isobutyl carbinol 12 g / t original ore are added to the roughing tailings for the first scavenging. Collector 1 butyl xanthate 30 g / t original ore, collector 2 butyl ammonium xanthate 15 g / t original ore, and foaming agent methyl isobutyl carbinol 10 g / t original ore are added to the tailings for the first scavenging, and the second scavenging is carried out. The scavenged tailings are returned in order, and the scavenged tailings are tailings one.

[0053] (5) The selected first-stage ore is re-grinded and re-selected. The amount of sodium phytate, an inhibitor in the re-grinding process, is 10g / t of the original ore; the grinding medium is ceramic balls, and the diameters of the ceramic balls used are φ5mm, φ4mm, φ3mm, and φ2mm, with a ratio of 2:3:2:2; the mill is an Aisha mill, with a filling rate of 35%, a grinding concentration of 50%, a grinding time of 3min, and a grinding fineness of -0.074mm accounting for 82% (of which -0.026mm particle size accounts for 36% of -0.074mm particle size, and +0.026-0.074mm accounts for 64% of -0.074mm particle size); after re-grinding The selected 1 middling ore is reselected, and the reselection process is one roughing selection, one selecting and one scavenging selection, wherein only the roughing selection process of the reselection is added with chemicals, and the reselection roughing collector 1 butyl xanthate and collector 2 butyl ammonium black medicine are 20g / t of original ore and 10g / t of original ore respectively, and the dosage of the foaming agent methyl isobutyl carbinol is 5g / t of original ore. No chemicals are added in the selecting and scavenging processes of the reselection, and the middling ore from the selected middling ore and the reselection scavenging middling ore are returned to the reselection roughing selection to obtain concentrate 2 and tailings 2. The concentrate 1 and concentrate 2 obtained in S4 are combined into the final concentrate, and the tailings 1 and tailings 2 obtained in S5 are combined into the final tailings.

[0054] 3. Ore dressing test indicators:

[0055] On the basis of detailed conditional tests, the grinding method of the original ore is cone mill-steel forging grinding, and grinding aids, activators and inhibitors are added during grinding. Based on the flotation process of "one roughing, two scavenging and three concentrating", the selected medium ore is re-selected by Ai sand mill-ceramic ball mill. The selected medium ore is subjected to "one roughing, one concentrating and one scavenging". Finally, the flotation closed-circuit test obtains good technical indicators. 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 Ore 100.00 2.15 100.00

[0058] From the results in Table 1, it can be seen that the Au grade of the concentrate is 31.01 g / t, which is 14.39 times richer than that of the original ore, and the recovery rate is as high as 88.24%.

[0059] Example 2

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

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

[0062] (2) adding 2200 g / t of sodium carbonate as an adjusting agent, 120 g / t of ore as a collector 1-amyl xanthate, 50 g / t of ore as a collector 2-butyl ammonium black powder, and 24 g / t of pine oil as an ore, and mixing the slurry, and then performing flotation roughing to obtain a roughing concentrate and a roughing tailing.

[0063] (3) The rough concentrate is subjected to three rounds of cleaning to obtain concentrate 1. The three rounds of cleaning are blank cleaning, in which the middlings from cleaning 1 are processed separately, and the middlings from cleaning 2 and cleaning 3 are returned to the previous level of operation in sequence.

[0064] (4) Collector 1 amyl xanthate 60 g / t of raw ore, collector 2 butyl ammonium xanthate 30 g / t of raw ore, and foaming agent pine oil 10 g / t of raw ore are added to the roughing tailings for the first scavenging. Collector 1 amyl xanthate 30 g / t of raw ore, collector 2 butyl ammonium xanthate 10 g / t of raw ore, and foaming agent pine oil 8 g / t of raw ore are added to the tailings for the first scavenging, and the second scavenging is carried out. The scavenged tailings are returned in order, and the scavenged tailings are tailings one.

[0065] (5) The selected first-stage ore is re-grinded and re-selected. The dosage of locust bean gum, an inhibitor in the re-grinding process, is 10g / t of the original ore; the grinding medium is ceramic balls, the diameters of the ceramic balls used are φ5mm, φ4mm, φ3mm, and φ2mm, and the ratio is 1:1:1:1; the mill is an argon sand mill, the filling rate is 33%, the grinding concentration is 50%, the grinding time is 3min30s, and the grinding fineness is -0.074mm, accounting for 85% (among which, -0.026mm particle size accounts for 38% of -0.074mm particle size, and +0.026-0.074mm accounts for 62% of -0.074mm particle size) The selected 1 middlings after regrinding are reselected, and the reselection process is one roughing selection, one selecting and one scavenging selection, wherein only the roughing selection process of the reselection is added with chemicals, and the reselection collector 1 amyl xanthate and collector 2 butyl ammonium black medicine are 24g / t of original ore and 10g / t of original ore respectively, and the dosage of the foaming agent pine alcohol is 5g / t of original ore. No chemicals are added in the selecting and scavenging processes of the reselection, and the selected middlings and the reselection scavenging middlings are returned to the reselection roughing selection to obtain concentrate 2 and tailings 2. The concentrate 1 and concentrate 2 obtained in S4 are combined into the final concentrate, and the tailings 1 and tailings 2 obtained in S5 are combined into the final tailings.

[0066] 3. Ore dressing test indicators:

[0067] On the basis of detailed conditional tests, activators and inhibitors were added into the grinding process. The grinding method of raw ore was cone mill-steel forging grinding. Based on the flotation process of “one roughing, two scavenging and three concentrating”, the selected medium ore was reselected by Ai sand mill-ceramic ball mill. The selected medium ore was subjected to “one roughing, one concentrating and one scavenging”. Finally, the flotation closed-circuit test obtained good technical indicators. 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 Ore 100.00 2.15 100.00

[0070] From the results in Table 2, we can see that the Au grade of the concentrate is 30.08 g / t, which is 14.00 times higher than that of the original ore, and the recovery rate is as high as 88.22%. By changing the grinding parameters and the type and dosage of the dressing agent, the grinding-flotation process can also recover Au in the ore well.

[0071] Example 3

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

[0073] (1) The gold ore was ground, and grinding aid 1: graphene oxide 1 g / t, grinding aid 2: isopentanol polyoxyethylene ether 100 g / t were added, the grinding medium was hexagonal steel forging, the diameter of the outer circle of the steel forging end face × the height of the column were φ30×35 mm, φ35×40 mm, φ40×50 mm, etc., the ratio was 1:2:1, the mill was a conical mill, the filling rate was 35%, the grinding concentration was 50%, the grinding time was 10 min 30 s, and the grinding fineness was -0.074 mm, accounting for 73% (among which, -0.026 mm particle size accounted for 33% of -0.074 mm particle size, +0.026-0.074 mm accounted for 67% of -0.074 mm particle size).

[0074] (2) adding 2200 g / t of sodium hydroxide as an adjusting agent, 120 g / t of ethyl xanthate as a collector 1, 60 g / t of ethylthiocarbamate as a collector 2, and 20 g / t of methyl isobutyl carbinol as a collector 2, and performing flotation roughing after slurry adjustment to obtain roughing concentrate and roughing tailings.

[0075] (3) The rough concentrate is subjected to three rounds of concentration to obtain concentrate 1. All three rounds of concentration are blank concentrations. The middlings from concentration 1 are processed separately, and the middlings from concentrations 2 and 3 are returned to the previous level of operation in sequence.

[0076] (4) Collector 1 ethyl xanthate 50 g / t original ore, collector 2 ethylthiocarbamate 30 g / t original ore, and foaming agent methyl isobutyl carbinol 12 g / t original ore are added to the roughing tailings for the first scavenging. Collector 1 ethyl xanthate 30 g / t original ore, collector 2 ethylthiocarbamate 10 g / t original ore, and foaming agent methyl isobutyl carbinol 10 g / t original ore are added to the tailings for the first scavenging, and the second scavenging is carried out. The scavenged tailings are returned in order, and the scavenged tailings are tailings one.

[0077] (5) The selected first-stage ore is re-grinded and re-selected. During the re-grinding process, 20g / t of xanthan gum, an inhibitor, is added; the grinding medium is ceramic balls, the diameters of the ceramic balls used are φ5mm, φ4mm, φ3mm, and φ2mm, and the ratio is 1:2:2:1. The mill is an argon sand mill, the filling rate is 35%, the grinding concentration is 60%, the grinding time is 2min30s, and the grinding fineness is -0.074mm, accounting for 80% (among which, -0.026mm particle size accounts for 34% of -0.074mm particle size, and +0.026-0.074mm accounts for 66% of -0.074mm particle size); after re-grinding The selected 1 middling ore is reselected, and the reselection process is one roughing selection, one selecting and one scavenging selection, wherein only the roughing selection process of the reselection is added with chemicals, the reselection roughing collector 1 ethyl xanthate and collector 2 ethylthiocarbamate are 24g / t of original ore and 12g / t of original ore respectively, and the dosage of the foaming agent methyl isobutyl carbinol is 5g / t of original ore, and no chemicals are added in the selecting and scavenging processes of the reselection, the selected middling ore and the reselection scavenging middling ore are returned to the reselection roughing selection to obtain concentrate 2 and tailings 2, the concentrate 1 and concentrate 2 obtained in S4 are combined into the final concentrate, and the tailings 1 and tailings 2 obtained in S5 are combined into the final tailings.

[0078] 3. Ore dressing test indicators:

[0079] On the basis of detailed conditional tests, activators and inhibitors were added into the grinding process. The grinding method of raw ore was cone mill-steel forging grinding. Based on the flotation process of “one roughing, two scavenging and three concentrating”, the selected medium ore was reselected by Ai sand mill-ceramic ball mill. The selected medium ore was subjected to “one roughing, one concentrating and one scavenging”. Finally, the flotation closed-circuit test obtained good technical indicators. 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 Ore 100.00 2.15 100.00

[0082] From the results in Table 3, we can see that the Au grade of the concentrate is 30.94 g / t, which is 14.41 times higher than that of the original ore, and the recovery rate is as high as 87.75%. By changing the grinding parameters and the type and dosage of flotation reagents, the grinding-flotation process can also recover Au in the ore well.

[0083] Comparative Example 1

[0084] Comparative Example 1 uses the same raw ore as Example 1, and changes the grinding method of the raw ore in Example 1 to traditional conical mill-steel ball grinding, the ratio of steel balls with diameters of φ30mm, φ35mm, and φ40mm is 3:4:3, the filling rate is 30%, the grinding concentration is 67%, the grinding time is 14min, the grinding fineness is -0.074mm, accounting for 70%, but the -0.026mm particle size accounts for 40% of the -0.074mm particle size, and the over-grinding phenomenon is serious; the grinding aid 1 graphene oxide and isopentanol polyoxyethylene ether, the roughing activator copper sulfate, and the inhibitor sodium phytate are not added to the grinding process, the time nodes of the first two additions are before the pH adjuster, and the latter two are after the pH adjuster; the process of re-grinding and re-selection of the selected and intermediate ore is consistent with that of Example 1; the types and amounts of various mineral processing agents are consistent with those of Example 1.

[0085] Ore dressing 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 Ore 100.00 2.15 100.00

[0088] Compared with Example 1, the grinding method of Comparative Example 1 obviously causes the ore to be over-grinded. The dynamic behavior of some gold-containing sulfide ores in the flotation process after over-grinding is also different from that of larger gold ores. Their momentum is small, and it is difficult to overcome the energy barrier between the ore particles and the bubbles and cannot adhere to the bubbles, making it difficult to recover. Comparing the results of Table 1 and Table 4, 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, and the Au recovery rate is 6.26 percentage points lower, which fully highlights the significant effect of adding grinding aids, activators, and inhibitors in the grinding process of the original ore in Example 1 in combination with hexagonal steel forging grinding.

[0089] Comparative Example 2

[0090] Comparative Example 2 uses the same raw ore as Example 1, the only difference is that no grinding aid is added during the grinding process, the grinding time is 13 minutes, the grinding fineness is -0.074 mm, accounting for 70%, and other conditions are consistent with Example 1.

[0091] Ore dressing 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 Ore 100.00 2.15 100.00

[0094] By comparing Example 1 and Comparative Example 2, it can be seen that, at the same grinding fineness, the grinding time of Example 1 with the addition of grinding aids is 11 minutes, and the grinding time of Comparative Example 2 without the addition of grinding aids is 13 minutes, indicating that the grinding aid has the effect of reducing the grinding time and energy consumption. The Au grade and Au recovery rate indicators of Comparative Example 2 are not as good as those of Example 1, and the Au recovery rate is 6.62 percentage points lower, which also shows that the grinding aid in the present invention plays the role of improving the grinding efficiency, ensuring the effects of the activator and the inhibitor, thereby improving the grade and yield of Au, and also plays the role of reducing the grinding time and energy consumption.

[0095] Comparative Example 3

[0096] Comparative Example 3 uses the same raw ore as Example 1, and the grinding method and flotation reagent system of the raw ore are consistent with those of Example 1; and the processing method of the first-stage ore in Example 1 is changed, and the first-stage ore is returned to the roughing, that is, no regrinding-refloating is performed. The flotation process is as shown in the attached figure. Figure 3 The dosing system of other flotation operations is consistent with that of Example 1. The second tailings of scavenging and selection are the final tailings, and the third operation of concentration is the final concentrate.

[0097] Ore dressing 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 Ore 100.00 2.14 100.00

[0100] By comparing the results in Table 1 and Table 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, and the Au recovery rate is 7.48 percentage points lower, which fully highlights the significant effect of adding inhibitors to the selected first ore and then grinding and selecting it in Example 1.

[0101] Comparative Example 4

[0102] Comparative Example 4 uses the same raw ore as Example 1, and the grinding method of the raw ore in Example 1 is changed to traditional conical mill-steel ball grinding, the ratio of steel balls with diameters of φ30mm, φ35mm, and φ40mm is 3:4:3, the filling rate is 30%, the grinding concentration is 67%, the grinding time is 14min, the grinding fineness is -0.074mm, accounting for 70%, but the -0.026mm particle size accounts for 40% of the -0.074mm particle size, and the over-grinding phenomenon is serious; the grinding aid 1 graphene oxide and isopentanol polyoxyethylene ether, the roughing activator copper sulfate, and the inhibitor sodium phytate are not added to the grinding process, the time nodes of the first two additions are before the pH adjuster, and the latter two are after the pH adjuster; and the treatment method of the selected first ore in Example 1 is changed, and the selected first ore is returned to the roughing, that is, no regrinding-refloatation is performed, and the flotation process is as shown in the attached Figure 4 The dosage of other flotation reagents is consistent with that in Example 1. The tailings from the scavenging operation II are the final tailings, and the tailings from the concentration operation III are the final concentrate.

[0103] Ore dressing 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 Ore 100.00 2.15 100.00

[0105] By comparing the results in Table 1 and Table 7, it can be seen that the Au recovery rate index of Comparative Example 4 is far inferior to that of Example 1, and the Au recovery rate is 9.29 percentage points lower, which fully highlights the remarkable effect of adding grinding aids, activators, inhibitors and hexagonal steel forging grinding ore in Example 1, and selecting the first ore by using wormwood mill-ceramic balls, adding inhibitors, regrinding and reselecting.

[0106] The above is only a preferred embodiment of the present invention. It should be understood that the present invention is not limited to the form disclosed herein, and should not be regarded as excluding other embodiments, but can be used in various other combinations, modifications and environments, and can be modified within the scope of the concept described herein through the above teachings or the technology or knowledge of the relevant field. The changes and modifications made by those skilled in the art shall not deviate from the spirit and scope of the present invention, and shall be within the scope of protection of the claims attached to the present invention.

Claims

1. A grinding method for a hard-to-select low-grade gold ore, wherein the hard-to-select low-grade gold ore has an Au grade of 1.8g / t-2.5g / t, an Al2O3 content of 55%-65%, a SiO2 content of 10%-20%, and more than 80% of the gold particles / gold-bearing minerals have a distribution particle size of less than 20 microns, characterized in that: The following steps are involved: Grinding aids, gold ore activators and gangue mineral inhibitors are added to the gold ore and ground; wherein the grinding aids are composed of grinding aids 1 and 2, grinding aid 1 is graphene oxide, and grinding aid 2 is sodium polyacrylate or isopentanol polyoxyethylene ether.

2. A grinding method for difficult-to-select low-grade gold ore according to claim 1, characterized in that: The amount of the grinding aid 1 is 1-5 g / t of the raw ore, and the amount of the grinding aid 2 is 50-100 g / t of the raw ore.

3. A grinding method for difficult-to-select low-grade gold ore according to claim 1, characterized in that: The gold ore activator is sodium sulfide or copper sulfate, and the dosage is 180-400g / t of the original ore; the gangue mineral inhibitor is xanthan gum, sodium phytate or locust bean gum, and the dosage is 200-500g / t of the original ore.

4. A grinding method for difficult-to-select low-grade gold ore according to any one of claims 1 to 3, characterized in that: The grinding medium used in the grinding is hexagonal steel forging.

5. A grinding method for difficult-to-select low-grade gold ore according to claim 4, characterized in that: The diameter of the circumscribed circle of the hexagonal steel forging end face × the column height include 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%.

6. A flotation method for difficult-to-select low-grade gold ore, characterized in that: A grinding method for a difficult-to-select low-grade gold ore as claimed in any one of claims 1 to 5, further comprising the following steps: 1) Roughing: pH adjuster, collector and frother are added to the flotation slurry obtained by grinding in sequence, and the slurry is stirred and adjusted before roughing to obtain roughing concentrate and roughing tailings; 2) Concentration: adding an inhibitor to the rougher concentrate and then concentrating it to obtain concentrate 1 and concentrating middlings; 3) Scavenging: adding a collector and a frother to the roughing tailings for scavenging to obtain tailings 1; 4) Regrinding and reselection: adding the gangue mineral inhibitor to the selected middling ore for regrinding treatment, and then adding a collector and a frother for reselection to obtain a second concentrate and a second tailing.

7. A flotation method for difficult-to-select low-grade gold ore according to claim 6, 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 amyl xanthate, and collector 2 is butyl ammonium black medicine or ethylthiocarbamate; the foaming agent is pine oil or methyl isobutyl carbinol.

8. A flotation method for difficult-to-select low-grade gold ore according to claim 7, characterized in that: In step 1), the dosage of pH adjuster during roughing is 1600-3000 g / t of raw ore, the dosage of collector 1 and collector 2 are 80-150 g / t of raw ore and 40-80 g / t of raw ore respectively, and the dosage of foaming agent is 20-30 g / t of raw ore; In step 2), the selection is blank selection; In step 3), during the scavenging, the dosage of collector 1 and collector 2 is 60-120 g / t of raw ore and 30-60 g / t of raw ore respectively, and the dosage of foaming agent is 18-27 g / t of raw ore; In step 4), the amount of gangue mineral inhibitor used in the regrinding treatment 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.

9. A flotation method for difficult-to-select low-grade gold ore according to claim 6, characterized in that: In step 2), the number of times of the selection is 3, namely selection 1, selection 2 and selection 3, the intermediate ore of selection 2 and selection 3 is returned to the previous level operation in sequence, and the intermediate ore of selection 1 is the selected intermediate ore; In step 3), the number of sweeping is 2 times, the sweeping tailings are returned to the previous level of operation, and the sweeping tailings are tailings 1; In step 4), the reselection process is one roughing selection, one concentrating selection, and one scavenging selection. The concentrating middlings are reselected, the scavenging middlings are reselected and returned to the roughing selection. The concentrating concentrate is the second concentrate, and the scavenging tailings are the second tailings.

10. A flotation method for difficult-to-select low-grade gold ore according to claim 6, characterized in that: In step 4), the grinding medium during the regrinding process is ceramic balls; the ceramic balls used include diameters of φ5mm, φ4mm, φ3mm, and φ2mm, the mill is an argon sand 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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