Method for improving recovery rate of refractory gold ore through cooperation of multi-stage dynamic precise ore grinding classification and composite reagent

Abstract

The invention relates to a method for improving the recovery rate of refractory gold ore through cooperation of multi-stage dynamic precise ore grinding classification and a composite reagent, and belongs to the technical field of energy-saving production. According to the method, through a three-stage classification system of a cyclone, a high-frequency fine screen and a centrifugal classifier, the centrifugal classified coarse particles with the particle size of + 0.074 mm are subjected to flash-speed preferential flotation to obtain preferential flotation concentrate; fine particles with the particle size being-0.074 mm and fine particles with the particle size being-0.355 mm after centrifugal classification are combined and mixed, and conventional flotation concentrate is obtained through conventional flotation; the preferential flotation concentrate and the conventional flotation concentrate are combined into total flotation concentrate, the conventional flotation tailings are discharged, and the preferential flotation tailings are returned to the ore grinding process. The production cost can be remarkably reduced, the flotation recovery rate is increased, and economic benefits are created. The process has the characteristics of high efficiency, low consumption and environmental protection, and is suitable for large-scale industrial application.

Description

Technical Field

[0001] The present invention relates to a method for synergistically improving the recovery rate of refractory gold ores by multi-stage dynamic precise grinding classification and composite reagents, and belongs to the technical field of energy-saving production. Background Art

[0002] Among China's gold geological reserves, lode gold accounts for 42.23% of the total reserves, placer gold accounts for 11.51%, and associated gold accounts for 46.26%. With the large-scale development and utilization of lode gold ore resources, the number of easily selected and processed gold ores is decreasing, while the number of refractory gold ores with fine dissemination size and low grade is increasing.

[0003] The traditional grinding classification process has the following problems: low classification efficiency: single cyclone classification easily leads to the recycling of fine-grained minerals in the sand return, with low classification accuracy of the cyclone. The proportion of fine-grained minerals (-0.074mm) in the sand return exceeds 15%, causing over-grinding; low efficiency of the classification equipment (the classification efficiency of a conventional cyclone is only 35-45%), resulting in a high circulating load (300-400%), and repeated grinding of minerals causes interface passivation.

[0004] Over-grinding during the grinding process of gold ore brings a series of problems, mainly including the following aspects: (1) Change in the surface properties of minerals: Over-grinding will over-crush the gold particles in the gold ore, resulting in changes in their surface properties, which may lead to an increase in the intergrowth of gold and gangue minerals, a decrease in the monomer dissociation degree of gold, affecting the subsequent separation effect and reducing the recovery rate of gold. (2) Encapsulation of gold particles: Excessive grinding will cause some originally dissociated gold particles to be encapsulated by fine-grained gangue minerals or other impurities. During the separation process, these encapsulated gold particles are difficult to come into full contact with the separation reagents and thus cannot be effectively recovered. (3) Uneven particle size of the grinding product: Over-grinding will lead to an uneven particle size distribution of the grinding product, with too high a content of fine-grained fractions, while there may still be unground particles in the coarse-grained part, which is not conducive to subsequent separation operations. (4) Increase in reagent consumption: Over-grinding increases the surface activity of minerals, which will adsorb more separation reagents, resulting in an increase in reagent dosage and thus an increase in reagent costs.

[0005] The traditional flotation process has problems such as over-grinding leading to the slimeification of gold minerals, high reagent consumption (e.g., the dosage of isoamyl xanthate > 90 g / t), and low recovery rate (about 92%). According to the research in "Mineral Resources Protection and Utilization" (2020), the gold recovery rate of the traditional grinding-flotation process is generally lower than 92%. The main reasons are that coarse-grained gold is repeatedly circulated in the classification-grinding circuit, resulting in over-crushing, and fine-grained gold is difficult to collect due to surface oxidation. A single reagent system is difficult to adapt to the surface property differences between coarse / fine-grained minerals. Coarse-grained pyrite has a slow adsorption kinetics, resulting in a lag in recovery. In addition, in the flotation operation, the fine-grained materials generated by over-grinding will make the flotation foam sticky, increase the foam stability, and make it difficult to break, resulting in the thickening of the foam layer, affecting the scraping of concentrate and the separation of foam, and reducing the flotation index. Secondly, when the over-ground pulp is subjected to dehydration operations such as concentration and filtration, due to too many fine-grained materials, the sedimentation speed of the pulp will slow down, the filtration resistance will increase, resulting in a decrease in dehydration efficiency, an increase in the moisture content of the product, and affecting subsequent operations such as drying.

[0006] According to the research in "Gold Ore Processing" (2022), the proportion of refractory gold ores globally has increased from 35% in 2015 to 45%. Among them, the recovery loss caused by over-grinding reaches 6-8%. The traditional process has three major technical bottlenecks: (1) The classification efficiency of the hydrocyclone is insufficient (<45%), resulting in a return sand rate of -0.074 mm fine particles > 15%; (2) A single reagent system is difficult to adapt to the surface property differences between coarse / fine-grained minerals; (3) There is a lack of means to prevent and control over-grinding, and the proportion of over-crushing of -0.01 mm reaches 12%.

[0007] Publication No. CN115007304A discloses a system and process for improving gold recovery rate by precisely controlling secondary classification of grinding and pre-recovery. The system includes a grinding system, a primary classification system, a secondary classification system, a conventional flotation operation system, and a preferential flotation operation system. The total gold concentrate operation is composed of the grinding primary classification operation, secondary classification, conventional flotation operation, preferential flotation operation, conventional flotation operation, and preferential flotation operation. It has the advantages of a simple system, less reagent consumption, high flotation efficiency, and high gold recovery rate. Although this application reduces the dosage of some reagents, there are still problems with insufficient classification accuracy and efficiency, and there is also the issue of how to further reduce the dosage of reagents and improve the recovery rate again.

[0008] Therefore, there is an urgent need for an innovative process that takes into account the grinding classification accuracy, reagent efficiency, and recovery rate. Summary of the Invention

[0009] In view of the problems and deficiencies of the above-mentioned existing technologies, the present invention provides a method for synergistically improving the recovery rate of refractory gold ores through multi-stage dynamic precision grinding classification and composite reagents. Through three core technologies, namely, a three-stage classification system of "hydrocyclone - high-frequency fine screen - centrifugal classifier", directional adsorption and synergistic effect of composite collectors, and intelligent prevention and control of over-grinding, the gold recovery rate of the present invention breaks through 96.18%, an increase of 4.18% compared with the traditional process. Moreover, the total amount of reagents is reduced, and the contradiction between the loss of coarse-grained gold due to over-grinding and the low collection efficiency of fine-grained gold is solved. The present invention is realized through the following technical solutions.

[0010] A method for synergistically improving the recovery rate of refractory gold ores through multi-stage dynamic precision grinding classification and composite reagents, which comprises the following steps:

[0011] (1) Primary classification by hydrocyclone: After ball-milling the gold ore, primary classification is carried out using a hydrocyclone equipped with intelligent prevention and control of over-grinding to obtain coarse particles of +0.355 mm and fine particles of primary classification.

[0012] (2) Secondary precision classification: The fine particles of primary classification are subjected to secondary classification through a high-frequency fine screen equipped with intelligent prevention and control of over-grinding to obtain fine-grained fractions of -0.355 mm under the screen and coarse-grained fractions of +0.355 mm on the screen.

[0013] (3) Tertiary centrifugal classification: The coarse particles of +0.355 mm from primary classification and the coarse-grained fractions of +0.355 mm after secondary precision classification are combined and mixed, and then centrifugal classification is carried out to obtain fine particles of -0.074 mm and coarse particles of +0.074 mm.

[0014] (4) Preferential flotation: The coarse particles of +0.074 mm after centrifugal classification are subjected to flash preferential flotation to obtain preferential flotation concentrate. The flotation reagents are 15 - 18 g / t of butyl xanthate, 10 - 20 g / t of sodium mercaptoacetate, and 15 g / t of pine oil.

[0015] (5) Conventional flotation: The fine particles of -0.074 mm and the fine-grained fractions of -0.355 mm after centrifugal classification are combined and mixed, and then conventional flotation is carried out to obtain conventional flotation concentrate. The flotation reagents are 180 g / t of nano-modified water glass, 28 - 30 g / t of Y98 high-efficiency collector, and 30 g / t of pine oil.

[0016] The preferential flotation concentrate and the conventional flotation concentrate are combined into the total flotation concentrate. The tailings of conventional flotation are discharged, and the tailings of preferential flotation are returned to the grinding process.

[0017] The gold ore is pyrite-type quartz vein gold ore with fine dissemination size and easy to be over-ground.

[0018] The intelligent prevention and control of over-grinding on the hydrocyclone in step (1) includes an XRF on-line analyzer and an intelligent prevention and control prediction model for over-grinding. The intelligent prevention and control prediction model is:

[0019] Y = α * P^β + γ, where Y is the cumulative percentage of a certain particle size, P is the cyclone pressure, and α, β, and γ are model parameters.

[0020] The cyclone pressure range for real-time adjustment of overgrinding intelligent prevention and control in step (1) is 0.15 - 0.2 MPa, and D50 = 0.2 mm.

[0021] The overgrinding intelligent prevention and control in step (2) includes an XRF on-line analyzer and an overgrinding intelligent prevention and control prediction model. The overgrinding intelligent prevention and control prediction model is:

[0022] η = δ * (A * f)^ε / sinθ, where η is the screening efficiency, A is the amplitude, f is the frequency, θ is the inclination angle, and δ and ε are parameters.

[0023] The amplitude range for real-time adjustment of the high-frequency fine screen in the overgrinding intelligent prevention and control in step (2) is 45 - 55 Hz, the amplitude range of the high-frequency fine screen is 0.3 - 0.7 mm, and the screen surface inclination angle range is 25 - 30°; the screen hole of the high-frequency fine screen is 0.355 mm.

[0024] In the process of rough particle flash flotation in step (4), the pulp concentration is 45% - 50%, and the flotation time ≤ 2 min.

[0025] In the process of conventional flotation in step (5), the pulp concentration is 30% - 35%, and the flotation time ≥ 12 min.

[0026] In the process of preferential flotation of the present invention, sodium thioglycolate and butyl xanthate are used in combination to simultaneously collect gold. Utilizing the high selectivity of sodium thioglycolate for gold minerals, it overcomes the single function of sodium thioglycolate only being used as an inhibitor in the flotation process in the prior art.

[0027] In the process of conventional flotation of the present invention, the modification of nano-modified sodium silicate is specifically as follows: 100 g of sodium silicate is placed in 200 mL of 0.5 mol / L HCl and treated for 2 h to obtain nano-modified sodium silicate.

[0028] The beneficial effects of the present invention are:

[0029] (1) The present invention uses a three-stage classification system of "cyclone - high-frequency fine screen - centrifugal classifier" to further improve the classification accuracy. The centrifugal classifier can separate finer particles, reduce the risk of overgrinding, and significantly reduce the total dosage of reagents after three-stage classification.

[0030] (2) In the process of "hydrocyclone - high - frequency fine screen", the present invention adds intelligent prevention and control of over - grinding. The XRF on - line analyzer in the intelligent prevention and control of over - grinding monitors the particle size distribution on the hydrocyclone or high - frequency fine screen in real time. According to the prediction model of intelligent prevention and control of over - grinding, it automatically adjusts the parameters of the classification equipment (such as hydrocyclone pressure, amplitude and frequency of high - frequency fine screen) to maximize the classification efficiency. The classification efficiency of the hydrocyclone is 45%, the classification efficiency of the high - frequency fine screen is 82%, the classification efficiency of the centrifugal classifier is 90%, and the total classification efficiency is ≥95%.

[0031] (3) In the stage of flash flotation, the present invention adopts the combination of butyl xanthate (20 - 30 g / t) and collector sodium mercaptoacetate. Utilizing the high selectivity of sodium mercaptoacetate for gold minerals, it further improves the recovery rate of coarse - grained gold.

[0032] (4) In the stage of conventional flotation, 200 g / t of nano - modified sodium silicate, 30 - 40 g / t of Y98 high - efficiency collector and 30 g / t of pine oil are added to enhance the collection effect of fine - grained gold. Aiming at the flotation property differences between coarse - grained gold (+0.355 mm) and fine - grained gold (-0.074 mm), sodium silicate modified by nano - silica is developed, with a particle size of 50 nm and a specific surface area of 380 m 2 / g. This modified sodium silicate can form a more stable selective hydration film on the mineral surface, effectively inhibiting the floating of gangue minerals, and the inhibition efficiency is increased by 40%.

[0033] (5) Through three core technologies of the "hydrocyclone - high - frequency fine screen - centrifugal classifier" three - stage classification system, directional adsorption and synergistic effect of composite collectors, and intelligent prevention and control of over - grinding, the present invention realizes that the gold recovery rate breaks through 96.18%, an increase of 4.18% compared with the traditional process. And the total amount of reagents is reduced, solving the contradiction between the loss of over - ground coarse - grained gold and the low collection efficiency of fine - grained gold.

[0034] (6) The present invention can significantly reduce production costs, improve the flotation recovery rate, and create economic benefits. This process has the characteristics of high efficiency, low consumption and environmental protection, and is suitable for large - scale industrial applications. Brief Description of the Drawings

[0035] Figure 1 It is the process flow chart of the present invention. Detailed Embodiments

[0036] The present invention will be further described below in conjunction with the drawings and specific embodiments.

[0037] Example 1

[0038] The method for synergistically improving the recovery rate of refractory gold ore by multi - stage dynamic precision grinding and classification and composite reagents includes the following steps:

[0039] (1) Primary classification of hydrocyclone: After ball-milling the gold ore (the gold ore is pyrite-type quartz vein gold ore with fine disseminated particle size and easy to over-grind), primary classification of the hydrocyclone with intelligent prevention and control of over-grinding is adopted to obtain coarse particles of +0.355 mm and fine particles of primary classification; the intelligent prevention and control of over-grinding on the hydrocyclone includes XRF on-line analyzer and over-grinding intelligent prevention and control prediction model. The over-grinding intelligent prevention and control prediction model is:

[0040] Y = α * P^β + γ, where Y is the cumulative percentage of a certain particle size, P is the hydrocyclone pressure, and α, β, γ are model parameters; the intelligent prevention and control of over-grinding adjusts the hydrocyclone pressure range in real time to 0.15 - 0.2 MPa, and D50 = 0.2 mm;

[0041] (2) Secondary precise classification: The fine particles of primary classification are subjected to secondary classification through a high-frequency fine screen with intelligent prevention and control of over-grinding to obtain fine particle size of -0.355 mm under the screen and coarse particle size of +0.355 mm on the screen; the intelligent prevention and control of over-grinding includes XRF on-line analyzer and over-grinding intelligent prevention and control prediction model. The over-grinding intelligent prevention and control prediction model is: η = δ * (A * f)^ε / sinθ, where η is the screening efficiency, A is the amplitude, f is the frequency, θ is the inclination angle, and δ, ε are parameters; the intelligent prevention and control of over-grinding adjusts the amplitude range of the high-frequency fine screen in real time to 45 - 55 Hz, the amplitude range of the high-frequency fine screen is 0.3 - 0.7 mm, and the screen surface inclination angle range is 25 - 30°; the screen hole of the high-frequency fine screen is 0.355 mm;

[0042] (3) Tertiary centrifugal classification: The coarse particles of +0.355 mm from primary classification and the coarse particles of +0.355 mm after secondary precise classification are combined and mixed for centrifugal classification to obtain fine particles of -0.074 mm and coarse particles of +0.074 mm;

[0043] (4) Preferential flotation: The coarse particles of +0.074 mm after centrifugal classification are subjected to flash preferential flotation to obtain preferential flotation concentrate. The flotation reagents are butyl xanthate 15 g / t, sodium mercaptoacetate 10 g / t, and pine oil 15 g / t; during the flash preferential flotation of coarse particles, the pulp concentration is 45%, and the flotation time is 2 min;

[0044] (5) Conventional flotation: The fine particles of -0.074 mm and the fine particle size of -0.355 mm after centrifugal classification are combined and mixed, and conventional flotation is adopted to obtain conventional flotation concentrate. The flotation reagents are nano-modified water glass 180 g / t, Y98 high-efficiency collector 28 g / t, and pine oil 30 g / t; during the conventional flotation process, the pulp concentration is 30%, and the flotation time is 12 min;

[0045] The preferential flotation concentrate and the conventional flotation concentrate are combined into the total flotation concentrate. The conventional flotation tailings are discharged, and the preferential flotation tailings are returned to the grinding process.

[0046] In this embodiment, the classification efficiency of the hydrocyclone is 45%, the classification efficiency of the high-frequency fine screen is 82%, the classification efficiency of the centrifugal classifier is 90%, and the total classification efficiency is ≥95%. The content of -0.355mm in the coarse particle size on the screen of the high-frequency fine screen under intelligent prevention and control of over-grinding is ≤5%. In this embodiment, the circulating load of the mill is reduced to 220%, and the overall energy consumption is reduced by 18%.

[0047] The specific flotation results are shown in Table 1.

[0048] Comparative Example 1

[0049] The same batch of gold ore was processed by the method of Publication No. CN115007304A, with the differences being that it did not go through three centrifugal classifications, there was no intelligent prevention and control of over-grinding, and the flotation reagents were different. Specifically:

[0050] (1) Primary classification by hydrocyclone: After ball-milling the gold ore (the gold ore is pyrite-type quartz vein gold ore with fine dissemination size and easy over-grinding), primary classification was carried out using a hydrocyclone to obtain coarse particles of +0.355mm and primary classification fine particles;

[0051] (2) Secondary precise classification: The primary classification fine particles were subjected to secondary classification through a high-frequency fine screen to obtain fine particle size of -0.355mm under the screen and coarse particle size of +0.355mm on the screen;

[0052] (4) Priority flotation: The coarse particles after primary classification and the coarse particle size of +0.355mm were combined, and flash priority flotation was used to obtain a priority flotation concentrate. The flotation reagents were butyl xanthate 25g / t and pine oil 15g / t; during the flash priority flotation of the coarse particles, the pulp concentration was 45% and the flotation time was 2min;

[0053] (5) Conventional flotation: The fine particle size of -0.355mm was subjected to conventional flotation to obtain a conventional flotation concentrate. The flotation reagents were water glass 200g / t, isopentyl xanthate high-efficiency collector 35g / t, and pine oil 30g / t; during the conventional flotation process, the pulp concentration was 30% and the flotation time was ≥12min;

[0054] The priority flotation concentrate and the conventional flotation concentrate were combined into the total flotation concentrate, the conventional flotation tailings were discharged, and the priority flotation tailings were returned to the grinding process.

[0055] In this comparative example, the hydrocyclone was not equipped with intelligent prevention and control of over-grinding, the classification efficiency of the hydrocyclone was only 35%, the classification efficiency of the high-frequency fine screen was 70%, and the total classification efficiency was 78%, resulting in a high circulating load (300 - 400%).

[0056] The specific flotation results are shown in Table 1.

[0057] Table 1

[0058]

[0059] As can be seen from Table 1, by adopting the present invention, the total gold grade of the gold concentrate obtained by the present invention is 51.02 g / t, and the gold recovery rate is 96.18%. Compared with the gold recovery rate obtained in Comparative Example 1, it is increased by 0.8 percentage points.

[0060] Example 2

[0061] The method for synergistically improving the recovery rate of refractory gold ore by multi-stage dynamic precision grinding classification and composite reagents comprises the following steps:

[0062] (1) Primary classification by hydrocyclone: After ball-milling the gold ore (the gold ore is pyrite-type quartz vein gold ore with fine dissemination size and easy to over-grind), primary classification by a hydrocyclone with intelligent prevention and control of over-grinding is carried out to obtain +0.355 mm coarse particles and primary classification fine particles; the intelligent prevention and control of over-grinding on the hydrocyclone includes an XRF on-line analyzer and an intelligent prevention and control prediction model of over-grinding. The intelligent prevention and control prediction model of over-grinding is:

[0063] Y = α * P^β + γ, where Y is the cumulative percentage of a certain particle size, P is the hydrocyclone pressure, and α, β, and γ are model parameters; the intelligent prevention and control of over-grinding adjusts the hydrocyclone pressure range in real time to 0.15 - 0.2 MPa, and D50 = 0.2 mm;

[0064] (3) Secondary precision classification: The primary classification fine particles are subjected to secondary classification by a high-frequency fine screen with intelligent prevention and control of over-grinding to obtain fine particles of -0.355 mm under the screen and coarse particles of +0.355 mm on the screen; the intelligent prevention and control of over-grinding includes an XRF on-line analyzer and an intelligent prevention and control prediction model of over-grinding. The intelligent prevention and control prediction model of over-grinding is: η = δ * (A * f)^ε / sinθ, where η is the screening efficiency, A is the amplitude, f is the frequency, θ is the inclination angle, and δ and ε are parameters; the intelligent prevention and control of over-grinding adjusts the amplitude range of the high-frequency fine screen in real time to 45 - 55 Hz, the amplitude range of the high-frequency fine screen is 0.3 - 0.7 mm, and the screen surface inclination angle range is 25 - 30°; the screen hole of the high-frequency fine screen is 0.355 mm;

[0065] (3) Tertiary centrifugal classification: The +0.355 mm coarse particles from the primary classification and the +0.355 mm coarse particles after the secondary precision classification are combined and mixed, and centrifugal classification is carried out to obtain fine particles of -0.074 mm and coarse particles of +0.074 mm;

[0066] (4) Preferential flotation: The +0.074 mm coarse particles after centrifugal classification are subjected to flash preferential flotation to obtain preferential flotation concentrate. The flotation reagents are butyl xanthate 18 g / t, sodium mercaptoacetate 20 g / t, and pine oil 15 g / t; the pulp concentration during the flash preferential flotation of the coarse particles is 50%, and the flotation time is 2 min;

[0067] (5)Conventional flotation: The fine particles of -0.074 mm and the fine fraction of -0.355 mm after centrifugal classification are combined and mixed, and conventional flotation is used to obtain conventional flotation concentrate. The flotation reagents are 180 g / t of nano-modified water glass, 30 g / t of Y98 high-efficiency collector, and 30 g / t of pine oil; during the conventional flotation process, the pulp concentration is 35%, and the flotation time is 12 min;

[0068] The preferential flotation concentrate and the conventional flotation concentrate are combined into the total flotation concentrate, the conventional flotation tailings are discharged, and the preferential flotation tailings are returned to the grinding process.

[0069] Example 3

[0070] The method for synergistically improving the recovery rate of refractory gold ore by multi-stage dynamic precision grinding classification and composite reagents includes the following steps:

[0071] (1) Primary classification by hydrocyclone: After ball milling the gold ore (the gold ore is pyrite-type quartz vein gold ore with fine disseminated particle size and easy to overgrind), primary classification is carried out using a hydrocyclone with intelligent prevention and control of overgrinding to obtain coarse particles of +0.355 mm and primary classification fine particles; among them, the intelligent prevention and control of overgrinding on the hydrocyclone includes an XRF on-line analyzer and an intelligent prevention and control prediction model of overgrinding. The intelligent prevention and control prediction model of overgrinding is:

[0072] Y = α * P^β + γ, where Y is the cumulative percentage of a certain particle size fraction, P is the hydrocyclone pressure, and α, β, γ are model parameters; the intelligent prevention and control of overgrinding adjusts the hydrocyclone pressure range in real time to 0.15 - 0.2 MPa, D50 = 0.2 mm;

[0073] (4) Secondary precision classification: The primary classification fine particles are subjected to secondary classification through a high-frequency fine screen with intelligent prevention and control of overgrinding to obtain a fine fraction of -0.355 mm under the screen and a coarse fraction of +0.355 mm on the screen; the intelligent prevention and control of overgrinding includes an XRF on-line analyzer and an intelligent prevention and control prediction model of overgrinding. The intelligent prevention and control prediction model of overgrinding is: η = δ * (A * f)^ε / sinθ, where η is the screening efficiency, A is the amplitude, f is the frequency, θ is the inclination angle, and δ, ε are parameters; the intelligent prevention and control of overgrinding adjusts the amplitude range of the high-frequency fine screen in real time to 45 - 55 Hz, the amplitude range of the high-frequency fine screen is 0.3 - 0.7 mm, and the screen surface inclination angle range is 25 - 30°; the screen hole of the high-frequency fine screen is 0.355 mm;

[0074] (3) Tertiary centrifugal classification: The primary classification +0.355 mm coarse particles and the +0.355 mm coarse particles after secondary precision classification are combined and mixed, and centrifugal classification is carried out to obtain fine particles of -0.074 mm and coarse particles of +0.074 mm;

[0075] (4) Preferential flotation: The +0.074 mm coarse particles after centrifugal classification are subjected to flash preferential flotation to obtain preferential flotation concentrate. The flotation reagents are butyl xanthate 16 g / t, sodium thioglycolate 18 g / t, and pine oil 15 g / t. During the flash preferential flotation of the coarse particles, the pulp concentration is 48% and the flotation time is 2 min;

[0076] (5) Conventional flotation: The -0.074 mm fine particles and the -0.355 mm fine fraction after centrifugal classification are combined and mixed, and conventional flotation is used to obtain conventional flotation concentrate. The flotation reagents are nano-modified water glass 180 g / t, Y98 high-efficiency collector 29 g / t, and pine oil 30 g / t. During the conventional flotation process, the pulp concentration is 32% and the flotation time is 12 min;

[0077] The preferential flotation concentrate and the conventional flotation concentrate are combined into the total flotation concentrate. The tailings of the conventional flotation are discharged, and the tailings of the preferential flotation are returned to the grinding process.

[0078] The specific embodiments of the present invention have been described in detail above in conjunction with the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those of ordinary skill in the art, various changes can be made without departing from the gist of the present invention.

Claims

1. A method for improving the recovery rate of refractory gold ores by combining multi-stage dynamic precision grinding and classification with composite reagents, characterized in that The following steps are involved: (1) Cyclone primary classification: After ball milling, the gold ore is subjected to primary classification using a cyclone equipped with an intelligent over-grinding prevention and control system to obtain coarse particles of +0.355 mm and primary classified fine particles; (2) Secondary precise classification: The fine particles of the primary classification are subjected to secondary classification through a high-frequency fine sieve with intelligent over-grinding prevention and control to obtain a fine particle size of -0.355 mm under the sieve and a coarse particle size of +0.355 mm on the sieve; (3) Three centrifugal classifications: The coarse particles of +0.355 mm obtained from the first classification and the coarse particles of +0.355 mm obtained from the second precision classification are combined and mixed, and then centrifuged to obtain fine particles of -0.074 mm and coarse particles of +0.074 mm; (4) Priority flotation: The coarse particles of +0.074 mm after centrifugal classification are subjected to flash priority flotation to obtain priority flotation concentrate. The flotation reagents are butyl xanthate 15-18 g / t, sodium thioglycolate 10-20 g / t, and pine oil 15 g / t; (5) Conventional flotation: The fine particles of -0.074 mm and the fine particles of -0.355 mm after centrifugal classification are combined and mixed, and conventional flotation is used to obtain conventional flotation concentrate. The flotation reagents are 180 g / t of nano-modified water glass, 28-30 g / t of Y98 high-efficiency collector, and 30 g / t of pine oil; The preferred flotation concentrate and the conventional flotation concentrate are combined into the total flotation concentrate, the conventional flotation tailings are discharged, and the preferred flotation tailings are returned to the grinding process.

2. The method of improving the recovery rate of refractory gold ore by combining multi-stage dynamic precision grinding and classification with composite reagents according to claim 1, characterized in that: The gold ore is a pyrite-type quartz vein gold ore with fine embedded grain size and easy to be over-grinded.

3. The method of improving the recovery rate of refractory gold ore by combining multi-stage dynamic precision grinding and classification with composite reagents according to claim 1, characterized in that: The intelligent prevention and control of over-grinding on the cyclone in step (1) includes an XRF online analyzer and an intelligent prevention and control prediction model for over-grinding. The intelligent prevention and control prediction model for over-grinding is: Y = α*P^β+γ, where Y is the cumulative percentage of a certain particle size, P is the cyclone pressure, and α, β, and γ are model parameters.

4. The method of improving the recovery rate of refractory gold ore by combining multi-stage dynamic precision grinding and classification with composite reagents according to claim 3 is characterized in that: The over-grinding intelligent prevention and control in step (1) adjusts the cyclone pressure range to 0.15-0.20 MPa in real time, and D50=0.2 mm.

5. The method of claim 1 for improving the recovery rate of refractory gold ores by combining multi-stage dynamic precision grinding and classification with composite reagents, characterized in that: In step (2), the over-grinding intelligent prevention and control includes an XRF online analyzer and an over-grinding intelligent prevention and control prediction model, and the over-grinding intelligent prevention and control prediction model is: η=δ*(A*)^ε / sinθ, where η is the screening efficiency, A is the amplitude, f is the frequency, θ is the inclination angle, and δ and ε are parameters.

6. The method of improving the recovery rate of refractory gold ore by combining multi-stage dynamic precision grinding and classification with composite reagents according to claim 5, characterized in that: In the step (2), the intelligent over-grinding prevention and control adjusts the high-frequency fine screen amplitude range to 45-55Hz, the high-frequency fine screen amplitude range to 0.3-0.7mm, the screen surface inclination range to 25-30°; the high-frequency fine screen mesh is 0.355mm.

7. The method of claim 1 for improving the recovery rate of refractory gold ores by combining multi-stage dynamic precision grinding and classification with composite reagents, characterized in that: In the step (4), during the flash preferential flotation of coarse particles, the pulp concentration is 45%-50%, and the flotation time is ≤2 min.

8. The method of claim 1 for improving the recovery rate of refractory gold ores by combining multi-stage dynamic precision grinding and classification with composite reagents, characterized in that: In the conventional flotation process of step (5), the ore pulp concentration is 30%-35%, and the flotation time is ≥12 minutes.

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