Cascade rotational flow classification beneficiation process for improving ore grinding grade and recovery rate and special system of cascade rotational flow classification beneficiation process

Abstract

The invention discloses a cascade rotational flow classification beneficiation process for improving the ore grinding grade and the recovery rate and a special system of the cascade rotational flow classification beneficiation process, and belongs to the technical field of mineral processing engineering. According to the invention, step-by-step extraction, on-demand return, accurate distribution and thickness division of materials with different particle fractions in ore pulp are realized, so that the particle size distribution of flotation feeding is effectively narrowed, over-grinding and under-grinding are avoided, the middle optimal flotation particle fraction is increased from the source, over-coarse and over-fine particle fractions are reduced, the particle size composition with a large middle part and two small ends is realized, and the flotation efficiency is improved. Therefore, flotation coarse and fine fraction tailings are greatly reduced, and finally the concentrate grade, the metal recovery rate and other production indexes are greatly improved.

Description

Technical Field

[0001] This invention belongs to the technical field of mineral processing engineering, specifically relating to a stepped cyclone classification and beneficiation process and its dedicated system for improving grinding grade and recovery rate. Background Technology

[0002] In mineral processing technologies such as metallurgy and mining, grinding and classification are crucial links connecting crushing and separation. Their purpose is to grind the ore to a suitable particle size (referred to as "qualified particle size") that allows for sufficient liberation of valuable minerals and gangue minerals, providing optimal feeding conditions for flotation and other refining operations. Currently, the grinding and classification process commonly used in mineral processing plants both domestically and internationally is a simple closed-loop model: one-stage coarse grinding – one-stage classification – two-stage fine grinding – two-stage classification. This means that after the raw ore is coarsely ground in the first stage ball mill, it is separated by classification equipment (such as spiral classifiers or hydrocyclones). The underflow (coarse particles) returns to the first stage ball mill, while the overflow (fine particles) enters the second stage fine grinding and classification. The overflow is the qualified product, and the underflow enters the second stage ball mill for regrinding.

[0003] However, this traditional model suffers from several long-standing technical bottlenecks, such as limited classification efficiency and a wide particle size distribution: a single classification device (such as a hydrocyclone) is limited by its separation principle and cannot achieve ideal precise classification. Its overflow product inevitably contains some incompletely dissociated "coarse" particles, while its underflow contains a large amount of already qualified "over-ground" fine mud. This uneven feed into flotation causes coarse particles to be lost due to their large mass and small surface area, while fine mud particles, due to their large specific surface area and tendency to become muddy, worsen the flotation environment, non-selectively adsorb large amounts of reagents, and overflow with the water flow, resulting in "tailing out." Furthermore, unreasonable circulating loads lead to high energy consumption: unqualified intermediate particle size materials are repeatedly circulated in the grinding and classification system, not only causing significant ineffective energy consumption in the ball mill and pumping equipment but also exacerbating the over-grinding phenomenon and generating more harmful fine mud. Product quality and recovery rate are difficult to achieve simultaneously: A major reason why it is difficult to improve the production recovery rate of ore dressing plants is that the tailings are characterized by "small in the middle and large at both ends." That is, the better flotation-grade metals in the middle of the tailings can be well floated into the concentrate product, while the tailings mainly consist of coarser and finer particles. Ultimately, the flotation tailings contain both coarse particles lost due to incomplete liberation and fine mud particles lost due to over-grinding, making it difficult to improve the recovery rate of valuable metals. Even if improvements are made by increasing the number of regrinding stages or optimizing operating parameters, the effect is often minimal, and this problem cannot be fundamentally solved at the system process level.

[0004] To address these issues, existing industries have implemented some improvements, such as optimizing hydrocyclone parameters and improving mill liners. However, these improvements primarily focus on individual equipment and fail to fundamentally resolve the problems of wide particle size distribution and high tailings rate at the system process level. Therefore, developing a novel grinding and classification process control method to achieve precise diversion and quality-differentiated processing of materials of different particle sizes has become an urgent problem to be solved. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a stepped cyclone classification and beneficiation process and its dedicated system for improving grinding grade and recovery rate, so as to solve the problems mentioned in the background art or achieve better technical effects.

[0006] To solve the above-mentioned technical problems, the inventors, through practice and summarization, derived the technical solution of this invention. This invention discloses a stepped cyclone classification and beneficiation process for improving grinding grade and recovery rate, the steps of which are as follows:

[0007] S1: The raw ore is transported to ball mill #1 through the feed passage. After preliminary coarse grinding, slurry is obtained. The slurry is then transported to hydrocyclone #1 through the discharge pump pipeline for the first stage of hydraulic classification.

[0008] S2: The overflow product obtained from the first stage of hydraulic classification in hydrocyclone 1 is directly separated and transported to the flotation thickening tank through the overflow path of hydrocyclone 1, so that it is completely removed from the grinding circulation system.

[0009] S3: The coarse-grained product obtained from the first stage of hydraulic classification in hydrocyclone 1 is transported to sand pump 2 through the bottom flow path of hydrocyclone 1, and then pumped into hydrocyclone 2 by sand pump 2 for the second stage of hydraulic classification.

[0010] S4: Set the parameters of hydrocyclone #2 so that hydrocyclone #2 has a coarser separation point than hydrocyclone #1, accurately classify the coarse-grained product of the underflow of hydrocyclone #1, and further divide the coarse-grained product into medium-coarse-grained and extra-coarse-grained parts.

[0011] The medium and coarse particles are overflowed into ball mill #2 for fine grinding.

[0012] The extra coarse particles are returned to the No. 1 ball mill as underflow for regrinding; the substandard coarse particles are precisely allocated to different mills according to particle size for effective grinding, optimizing grinding efficiency and reducing over-grinding and energy consumption.

[0013] S5: The material after fine grinding in ball mill #2 is pumped to hydrocyclone #3 for third-stage hydrocyclone classification. The overflow is then fed into flotation thickening tank as a qualified product for subsequent flotation operations.

[0014] S6: The underflow sediment obtained from the third stage of cyclone classification is returned to the No. 2 ball mill through the underflow path of the No. 2 cyclone separator for further fine grinding, forming a closed-loop cycle. This ensures that all materials entering the fine grinding loop must be ground to the qualified particle size before overflowing into the flotation system, strictly guaranteeing the particle size qualification rate of the final product, while maximizing the processing capacity of the fine grinding mill.

[0015] Furthermore, in S1, the slurry concentration is 60-75%.

[0016] Furthermore, in S2, the qualified particle size of the overflow product obtained after hydraulic classification in the first stage of hydrocyclone #1 is -0.074mm.

[0017] Furthermore, in S3, the particle size of the coarse-grained product obtained by the first stage of hydraulic classification of the No. 1 hydrocyclone is 0.074~1.5mm.

[0018] Furthermore, in S4, the separation point of the #2 hydrocyclone is set to 0.3 mm; the medium-coarse particle size is 0.074~0.3 mm; and the extra-coarse particle size is 0.3~1.5 mm.

[0019] Furthermore, in S5, the overflow particle size obtained from the third stage of swirl classification is -0.074 mm.

[0020] Furthermore, in S6, the bottom sediment particle size obtained by the third stage of vortex classification is 0.074~0.3mm.

[0021] Furthermore, any of the above-mentioned dedicated systems for the graded cyclone classification and beneficiation process for improving grinding grade and recovery rate include a three-stage gradient cyclone module and a two-stage ball mill module, wherein the gradient cyclone modules are connected in sequence through pumping pipelines.

[0022] The first-stage cyclone module includes a #1 cyclone, the feed end of which is connected to a #1 ball mill via a pumping pipeline, the first output end of which is directly connected to the flotation system, and the second output end of which is connected to a #2 sand pump.

[0023] The second-stage cyclone module includes a #2 cyclone, a #2 sand pump connected between the #2 cyclone and the #1 cyclone, the first output end of the #2 cyclone connected to the #2 ball mill via a pipeline, and the second output end of the #2 cyclone connected to the #1 ball mill via a pipeline.

[0024] The third-stage cyclone module includes a #3 cyclone. The feed end of the #3 cyclone is connected to the feed end of the #2 ball mill via a pumping pipeline. The first output end of the #3 cyclone is connected to the direct flotation system via a pipeline. The second output end of the #3 cyclone is connected to the feed end of the #2 ball mill via a pipeline.

[0025] Furthermore, the No. 2 ball mill is equipped with steel balls or steel segments with a diameter of 20-40mm for fine grinding operations.

[0026] Furthermore, the feeding end of the No. 2 ball mill is connected to the No. 2 pump tank via a pipeline, the No. 2 pump tank is connected to the feeding end of the No. 3 sand pump via a pipeline, and the No. 3 sand pump is connected to the feeding end of the No. 3 hydrocyclone via a pipeline.

[0027] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0028] (1) By setting up multi-stage hydrocyclones and forming a specific closed loop with ball mills of different functions according to a specific pipeline design, this invention realizes the "gradual extraction, on-demand return, precise diversion, and coarse and fine classification" of different particle sizes in the slurry. This effectively narrows the particle size distribution of the flotation feed, eliminates over-grinding and under-grinding, increases the optimal floatable particle size in the middle from the source, reduces excessively coarse and excessively fine particle sizes, and achieves a particle size composition of "large in the middle and small at both ends". This greatly improves the particle size uniformity of the final flotation feed, thereby significantly reducing the tailing of coarse and fine particles in the flotation, and ultimately significantly improving the concentrate grade and metal recovery rate and other production indicators.

[0029] (2) The present invention separates the qualified ultrafine particles in advance after the first stage of classification and sends them directly to flotation so that they no longer participate in any subsequent grinding process. This is the most fundamental and effective measure to solve the problem of over-grinding, thereby completely eliminating the phenomenon of "over-grinding".

[0030] (3) The present invention separates the coarsest particle size (underflow of 2# hydrocyclone) in the system and returns it to the 1# ball mill with the strongest coarse grinding capacity, realizing "coarse grinding of coarse particles", ensuring that the coarse particles can be effectively crushed and dissociated, avoiding under-grinding loss due to insufficient circulation, and effectively solving the "under-grinding" problem.

[0031] (4) Because the flotation feed has a uniform particle size and sufficient dissociation, the coarse particles and fine mud particles are reduced significantly at the same time. This results in a particle size distribution with the optimal floatable particles in the middle being large and the excessively coarse and fine particles on both sides being small. The flotation operation is carried out under optimal particle size conditions, making it difficult for coarse particles to fall off and for fine mud to be lost. This significantly reduces the content of valuable metals in the tailings and improves the recovery rate.

[0032] (5) Each ball mill in the entire process system of the present invention can operate independently. Ball mill #1 mainly processes coarse particles, and ball mill #2 mainly processes intermediate particles. This reduces the wasted energy of the equipment, improves the grinding efficiency, reduces the energy consumption per ton of ore from the overall system, and may improve the system's processing capacity.

[0033] (6) In the flotation process, the concentrate grade of this invention is significantly improved, the metal recovery rate is greatly increased, and the overall technical and economic indicators are better than those of the traditional process. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the optimized process of the stepped cyclone classifying grinding system of the present invention;

[0035] Figure 2 This is a schematic diagram of the traditional mineral processing technology in Comparative Example 1;

[0036] The components are as follows: 1. Feed passage; 2. Ball mill #1; 3. Pump sump #1; 4. Sand pump #1; 5. Hydrocyclone #1; 6. Overflow path of hydrocyclone #1; 7. Bottom path of hydrocyclone #1; 8. Sand pump #2; 9. Hydrocyclone #2; 10. Bottom path of hydrocyclone #2; 11. Overflow path of hydrocyclone #2; 12. Ball mill #2; 13. Pump sump #2; 14. Sand pump #3; 15. Bottom path of hydrocyclone #2; 16. Hydrocyclone #3; 17. Overflow path of hydrocyclone #3. Detailed Implementation

[0037] To make the above-mentioned objectives, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to specific examples.

[0038] Unless otherwise specified, the equipment used in the following embodiments are all commercially available products.

[0039] Example 1

[0040] A stepped cyclone classification and beneficiation system for improving grinding grade and recovery rate includes a three-stage gradient cyclone module and two-stage ball mill module, wherein the three-stage gradient cyclone module is connected in sequence through pump pipelines.

[0041] The first-stage cyclone module includes a #1 hydrocyclone 5. The feed end of the #1 hydrocyclone 5 is connected to a #1 ball mill 2 via a pump pipeline. The first output end of the #1 hydrocyclone 5 is directly connected to the flotation system, and the second output end of the #1 hydrocyclone is connected to a #2 sand pump 8. The first stage of cyclone classification of materials is carried out in the #1 hydrocyclone 5, resulting in: materials with particle sizes <0.074mm as overflow directly entering the flotation process, completely removing them from the grinding circulation system, thus completely avoiding the "over-grinding" of qualified materials; and sand with particle sizes of 0.074~1.5mm as underflow (non-compliant coarse particles) entering the subsequent cyclone module for targeted regrinding.

[0042] The second-stage cyclone module includes a #2 cyclone 9, a #2 sand pump 8 connected between the #2 cyclone 9 and the #1 cyclone 5, the first output end of the #2 cyclone 9 is connected to the #2 ball mill 12 through a pipeline, and the second output end of the #2 cyclone 9 is connected to the #1 ball mill through a pipeline. Hydrocyclone 9 (No. 2) has a coarser separation point (0.3mm), enabling precise classification of the underflow (coarse sand) from hydrocyclone 5 (No. 1). After the second stage of hydrocyclone classification, the coarse sand is further divided into two parts: the medium-coarse particle size (0.074~0.3mm) flows as overflow into ball mill 12 (No. 2 ball mill 12 has the highest energy utilization rate when processing medium-sized materials); the extra-coarse particle size (0.3~1.5mm) returns as underflow to ball mill 1 (No. 1 ball mill) for regrinding (ensuring that the coarsest particles are always processed in the most suitable equipment (coarse mill), avoiding them from "hiding" in the fine mill and being over-ground or not ground finely enough). This process achieves "coarse-fine classification," accurately distributing substandard coarse particles to different mills for most efficient grinding, greatly optimizing grinding efficiency, and is a key step in reducing over-grinding and energy consumption.

[0043] As a preferred option, the No. 2 ball mill 12 is loaded with smaller steel balls or steel segments with a diameter of 20~40mm, specifically for fine grinding operations.

[0044] The third-stage cyclone module includes a #3 cyclone 16. The feed end of the #3 cyclone 16 is connected to the feed end of the #2 ball mill via a pumping pipeline. The first output end of the #3 cyclone is connected to the direct flotation system via a pipeline. The second output end of the #3 cyclone 16 is connected to the feed end of the #2 ball mill 12 via a pipeline.

[0045] Specifically, the feed end of the #1 hydrocyclone 5 is connected to the discharge end of the #1 sand pump 4 via a pipeline, the feed end of the #1 sand pump 4 is connected to the #1 pump tank 3 via a pipeline, and the #1 pump tank 3 is connected to the discharge end of the #1 ball mill 2 via a pipeline.

[0046] As a preferred option, the raw ore is transported to the feed end of ball mill 2 through feed passage 1, and the raw ore is fed into feed passage 1 from the raw ore bin by belt feeding.

[0047] The first ball mill module includes ball mill #1 2. The feed end of ball mill #1 2 receives raw ore through feed passage 1 for preliminary crushing of the raw ore. The feed end of ball mill #1 2 is connected to the second output end of hydrocyclone #2 9 through the bottom flow passage 10 of hydrocyclone #2. This allows the underflow obtained from the second stage hydrocyclone classification to be returned to ball mill #1 for "re-grinding". This ensures that the coarsest particles are always processed in the most suitable equipment (coarse mill) and avoids them from "hiding" in the fine mill and being over-ground or not ground finely. The substandard coarse particles are accurately distributed to different mills according to particle size for the most efficient grinding, which greatly optimizes grinding efficiency and is a key link in reducing over-grinding and energy consumption.

[0048] The second-stage ball mill module includes ball mill #2 12. The feed end of ball mill #2 12 is connected to the first output end of hydrocyclone #2 9 via overflow path 11, allowing the medium-coarse particles (0.074-0.3mm) obtained from the second-stage hydrocyclone classification to overflow into ball mill #2 for "fine grinding." This is the most efficient grinding method because ball mill #2 12 has the highest energy utilization rate when processing medium-sized materials. The feed end of ball mill #2 12 is connected to the second output end of hydrocyclone #3 16 via bottom flow path 15, forming a closed-loop fine grinding cycle between hydrocyclone #3 16 and ball mill #2 12. This ensures that all materials entering the fine grinding loop must be ground to a qualified particle size (-0.074mm) before overflowing into the flotation system, strictly guaranteeing the particle size qualification rate of the final product while maximizing the processing capacity of the fine grinding mill.

[0049] Preferably, the feeding end of ball mill 12 is connected to pump tank 13 via a pipeline, pump tank 13 is connected to the feed end of sand pump 14 via a pipeline, and sand pump 14 is connected to the feed end of hydrocyclone 3 via a pipeline.

[0050] Example 2

[0051] A stepped cyclone classification and beneficiation process to improve grinding grade and recovery rate, such as Figure 1 As shown, the steps are as follows:

[0052] S1: The raw ore is fed to ball mill #1 2 through feed passage 1. After preliminary coarse grinding, a slurry is obtained. The slurry concentration (solid mass percentage) is controlled at 60-75% to ensure suitable fluidity. The ground slurry enters pump pool #1 3 through pipeline (pump pool #1 3 mainly serves to buffer, stir, and stabilize the slurry level, ensuring a stable and continuous supply to the subsequent sand pump and hydrocyclone, without changing the basic chemical form of the slurry). Then, it enters sand pump #1 4 through pipeline (sand pump #1 4 provides the conveying power for the slurry, mainly changing the pressure and flow rate of the slurry to match the working requirements of the hydrocyclone, without changing its chemical composition). After being conveyed through the discharge pump pipeline, the slurry is transported to hydrocyclone #1 5 for the first stage of hydraulic classification.

[0053] S2: The overflow product obtained from the first stage of hydraulic classification in hydrocyclone 5 is set as the finest particle size that first meets the flotation requirements in the system. It is directly separated and transported to the flotation thickening tank through overflow path 6 of hydrocyclone 1, so that it is completely removed from the grinding circulation system, thereby completely avoiding the "over-grinding" of this qualified material in subsequent grinding. (Fineest particle size range: The first qualified particle size set by the system is -0.074mm (i.e. -200 mesh); this is the typical upper limit of particle size that is most effective for the recovery of most minerals (including tungsten ore) in flotation operations. The separation is automatically completed by the centrifugal classification principle of the hydrocyclone. The fine particles that meet the particle size requirements are discharged from the overflow pipe at the top of the hydrocyclone due to their small mass and weak centrifugal force, and are led out of the system through overflow path 6 of hydrocyclone 1). The material overflowing from hydrocyclone 5 is the first batch of qualified product, with a particle size of 0~0.074mm.

[0054] S3: The underflow (non-compliant coarse-grained particles, with a particle size of 0.074~1.5mm) obtained after the first stage hydraulic classification of hydrocyclone 5 is transported to sand pump 8 through the underflow path 7 of hydrocyclone 1, and then pumped into hydrocyclone 9 through sand pump 8.

[0055] S4: Set the parameters of hydrocyclone 9 (to achieve a coarser separation point). (The purpose of setting a coarser separation point: Hydrocyclone 9 is set to a coarser separation point (e.g., 0.3mm) than hydrocyclone 1. This is to accurately classify the underflow (coarse sand) from hydrocyclone 1, further dividing the coarse sand into two parts: medium-coarse particles (0.074~0.3mm): These are fed into ball mill 2 as overflow for "fine grinding," which is the most efficient grinding method because ball mills have the highest energy utilization rate when processing medium-sized materials; extra-coarse particles (0.3~1.5mm): These are returned to ball mill 1 as underflow for "regrinding." This ensures that the coarsest particles are always processed in the most suitable equipment (coarse mill), avoiding them from "hiding" in the fine mill.) "If the grinding is too fine or insufficient, the sediment obtained from the first stage of hydraulic classification undergoes a second stage of hydrocyclone classification. The resulting overflow (0.074~0.3mm particle size) enters the No. 2 ball mill 12 through the overflow path 11 of the No. 2 hydrocyclone (the No. 2 ball mill 12 is filled with 20~40mm steel balls or steel segments, which can perform fine grinding on the material); the resulting underflow sediment (0.3~1.5mm particle size) is returned to the No. 1 ball mill 2 through the underflow path 10 of the No. 2 hydrocyclone for regrinding, to ensure that the coarse particles are fully and effectively processed. This step achieves "coarse and fine classification", which accurately distributes the substandard coarse particles to different mills for the most efficient grinding, greatly optimizing grinding efficiency and is a key link in reducing over-grinding and energy consumption."

[0056] S5: The material after fine grinding by ball mill 12 is transported to pump pool 13 through pipeline, then transported to sand pump 14 through pipeline, and then pumped into hydrocyclone 16 through pumping pipeline (hydrocyclone 16 is used as a check and classification device to control the particle size of the target material to be finer, with 0~0.074mm accounting for more than 85%), for the third stage of hydrocyclone classification. The overflow (0~0.074mm particle size) is collected into overflow path 6 of hydrocyclone 1 through pipeline, and finally transported to flotation thickening tank.

[0057] S6: The underflow sediment (0.074~0.3mm) obtained from the third stage cyclone classification is returned to the No. 2 ball mill 12 through the underflow path 15 of the No. 2 cyclone separator for further fine grinding, forming a closed-loop cycle. This ensures that all materials entering the fine grinding loop must be ground to the qualified particle size (-0.074mm) before overflowing into the flotation system, strictly guaranteeing the particle size qualification rate of the final product, while maximizing the processing capacity of the fine grinding mill.

[0058] Example 3

[0059] To ensure the stable and efficient operation of the system of this invention, an automated control system (DCS / PLC) is used to monitor and control key parameters in real time; specifically as follows:

[0060] Pump pool level control: Each pump pool is equipped with a level gauge, and the level is stabilized by adjusting the pump frequency to ensure stable ore feeding;

[0061] Feed concentration control: Online concentration meters are installed at key feed points, and the feed concentration is stabilized within the optimal range by automatically adjusting the water replenishment valve (e.g., feed concentration of 65% ± 2% for hydrocyclone #1).

[0062] Feed pressure control: The feed pressure of the hydrocyclone is stabilized by a variable frequency pump to ensure classification efficiency;

[0063] Particle size monitoring: Optional online particle size analyzer (such as PSD) is used to monitor the particle size of the final product (overflow of hydrocyclones #1 and #3) in real time, as a basis for feedback control.

[0064] Comparative Example 1

[0065] One mineral processing technology, following traditional methods, employs a single closed-circuit grinding step, such as... Figure 2 As shown, the process is as follows:

[0066] After being ground in a single ball mill, the raw ore is pumped to a single hydrocyclone group for classification. The overflow of the hydrocyclone (-0.074mm) all enters the flotation system, while the underflow of the hydrocyclone is all returned to the same ball mill to form a closed loop.

[0067] The drawback of this process is that a wide range of return sand (from particles just close to 0.074 mm to several millimeters) all enter the same mill, causing qualified fine particles to be repeatedly circulated and "over-ground," generating a large number of micro-particles that are difficult to recover; while the real coarse particles may not get enough grinding opportunities, resulting in "polarization" of particle size and deteriorating flotation conditions.

[0068] A tungsten ore beneficiation plant, while maintaining the same processing capacity, implemented the cascade cyclone classifying grinding system in Example 2 and the beneficiation process in Comparative Example 1. The comparison of various index data and changes in flotation feed particle size after implementation are shown in Table 1 below.

[0069] Table 1. Flotation feed particle size distribution (%) of products after applying the process in Example 2 and Comparative Example 1

[0070]

[0071] As shown in Table 1, the cumulative content of -0.074mm particles in the flotation feed of the present invention increased from 72.31% to 86.64%, an increase of 14.33%; the content of overly coarse particles (0.15-0.074mm) that are difficult to float decreased by 14.33%, the content of overly fine particles (-0.01mm particles) decreased from 22.17% to 9.45%, a decrease of 12.62%, and the content of intermediate easily floatable particles (-0.074-0.019mm) increased by 26.92%. This invention significantly optimizes the particle size distribution of flotation feed, increasing the proportion of qualified particle sizes (the yield of the -0.074mm qualified particle size increases from 72.31% to 86.64%), providing more effectively recoverable material for flotation, effectively suppressing "over-grinding," and drastically reducing the yield of harmful excessively fine particles (-0.01mm) from 22.17% to 9.45%, reducing metal loss and reagent consumption caused by mud formation, and reducing "under-grinding" particles: the yield of difficult-to-float excessively coarse particles (+0.074mm) is simultaneously reduced, improving the liberation degree of the target mineral. Enrichment of easily floatable particles: the yield of the intermediate particle size (-0.074~0.019mm), which has the highest flotation efficiency, is significantly increased, laying the foundation for high recovery rates.

[0072] The particle size distribution of tailings products after flotation in Example 2 and Comparative Example 1 is shown in Table 2 below.

[0073] Table 2. Particle size distribution of tailings products after flotation in Example 2 and Comparative Example 1.

[0074]

[0075] As shown in Tables 1 and 2, the new process of this invention produces a more uniform WO3 metal distribution in the flotation tailings. The metal distribution in the coarse-grained (0.075~0.15mm) and fine-grained (-0.01mm) tailings is reduced by 18.52% and 15.59% respectively, both showing a significant decrease. Ultimately, the tungsten recovery rate is increased by 10.2 percentage points, the tailings grade is significantly reduced, and the annual economic benefits are significantly increased.

[0076] In the flotation feed (Table 1), the distribution of WO3 metal under the new process is more concentrated in the easily floatable intermediate particle size (such as the higher distribution rate in the range of -0.045 to +0.019 mm).

[0077] In the tailings (Table 2), the overall grade of the tailings from the new process decreased from 0.09% to 0.05%, and the distribution of metal loss was fundamentally improved.

[0078] The tailings exhibit more uniform ore separation, reflected in the fact that the WO3 distribution of each particle size is no longer highly concentrated in the difficult-to-process coarse and fine particles. For example, in Comparative Example 1, the metal loss of the coarse particle size (+0.075mm) and the fine particle size (-0.01mm) accounted for approximately 45% of the total tailings loss, while in Example 2, this proportion decreased to approximately 25%. This indicates that the metal loss is due to the near-normal separation efficiency of each particle size, rather than because specific particle sizes were not effectively separated at all.

[0079] The loss of key particle size was sharply reduced: the metal distribution rate of coarse and fine particles in the tailings decreased significantly by 18.52 and 15.59 percentage points, respectively, proving that the process effectively solved the direct loss of metal caused by "under-grinding" and "over-grinding".

[0080] This invention achieves precise material separation and targeted grinding according to particle size through a "step-by-step cyclone classification" process, fundamentally solving the contradiction of "over-grinding" and "under-grinding" coexisting in traditional single-stage closed-circuit grinding. Its beneficial effects are ultimately reflected in: producing flotation feed with highly optimized particle size distribution, maximizing the enrichment of tungsten metal in easily floatable particles, and significantly reducing losses in coarse and fine particle sizes, thereby greatly improving metal recovery rate and economic benefits while maintaining the same throughput.

Claims

1. A stepped cyclone classification and beneficiation process for improving grinding grade and recovery rate, characterized in that, The steps are as follows: S1: The raw ore is transported to ball mill #1 (2) through the feed passage (1). After preliminary coarse grinding, slurry is obtained. The slurry is then transported to hydrocyclone #1 (5) through the discharge pump pipeline for the first stage of hydraulic classification. S2: The overflow product obtained from the first stage of hydraulic classification by hydrocyclone 1 (5) is directly separated and transported to the flotation thickening tank through the overflow path (6) of hydrocyclone 1, so that it is completely removed from the grinding circulation system. S3: The coarse-grained product obtained from the first stage of hydraulic classification by hydrocyclone 1 (5) is transported to sand pump 2 (8) through the bottom flow path (7) of hydrocyclone 1, and then pumped into hydrocyclone 2 (9) by sand pump 2 (8) for the second stage of hydraulic classification. S4: Set the parameters of hydrocyclone 2 (9) so that hydrocyclone 2 (9) has a coarser separation point than hydrocyclone 1, accurately classify the coarse-grained product of the underflow of hydrocyclone 1, and further divide the coarse-grained product into two parts: medium-coarse-grained and extra-coarse-grained. The medium and coarse particles are fed into ball mill #2 (12) as overflow for fine grinding; The extra coarse particles are returned to the No. 1 ball mill (2) as underflow for regrinding; the substandard coarse particles are accurately distributed to different mills according to particle size for effective grinding, optimizing grinding efficiency and reducing over-grinding and energy consumption; S5: The material after fine grinding by ball mill #2 (12) is transported to hydrocyclone #3 (16) through pump pipeline for third-stage hydrocyclone classification. The overflow obtained is collected into flotation concentration tank through pipeline and used as qualified product for subsequent flotation operation. S6: The underflow sediment obtained from the third stage of cyclone classification is returned to the ball mill (12) through the underflow path (15) of the No. 2 cyclone separator for further fine grinding, forming a closed-loop circulation.

2. The stepped cyclone classification and beneficiation process for improving grinding grade and recovery rate according to claim 1, characterized in that, In S1, the slurry concentration is 60-75%.

3. The stepped cyclone classification and beneficiation process for improving grinding grade and recovery rate according to claim 1, characterized in that, In S2, the qualified particle size of the overflow product obtained by the first stage of hydraulic classification of the 1# hydrocyclone (5) is -0.074mm.

4. The stepped cyclone classification and beneficiation process for improving grinding grade and recovery rate according to claim 1, characterized in that, In S3, the particle size of the coarse-grained product obtained by the first stage of hydraulic classification of the 1# hydrocyclone (5) is 0.074~1.5mm.

5. The stepped cyclone classification and beneficiation process for improving grinding grade and recovery rate according to claim 1, characterized in that, In S4, the separation point of the 2# hydrocyclone (9) is set to 0.3 mm; the medium-coarse particle size is 0.074~0.3 mm; and the extra-coarse particle size is 0.3~1.5 mm.

6. The stepped cyclone classification and beneficiation process for improving grinding grade and recovery rate according to claim 1, characterized in that, In S5, the overflow particle size obtained from the third stage of swirl classification is -0.074 mm.

7. The stepped cyclone classification and beneficiation process for improving grinding grade and recovery rate according to claim 1, characterized in that, In S6, the bottom sediment particle size obtained by the third stage of vortex classification is 0.074~0.3mm.

8. A dedicated system for a stepped cyclone classification and beneficiation process as described in any one of claims 1 to 7, characterized in that, It includes a three-stage gradient cyclone module and two-stage ball mill modules, with the gradient cyclone modules connected sequentially via pumping pipelines; The first stage cyclone module includes a #1 cyclone (5), the feed end of the #1 cyclone (5) is connected to a #1 ball mill (2) through a pumping pipeline, the first output end of the #1 cyclone (5) is directly connected to the flotation operation system, and the second output end of the #1 cyclone (5) is connected to a #2 sand pump (8). The second-stage cyclone module includes a 2# cyclone (9), a 2# sand pump (8) is connected between the 2# cyclone (9) and the 1# cyclone (5), the first output end of the 2# cyclone (9) is connected to the 2# ball mill (12) through a pipeline, and the second output end of the 2# cyclone (9) is connected to the 1# ball mill (2) through a pipeline. The third-stage cyclone module includes a 3# cyclone (16). The feed end of the 3# cyclone (16) is connected to the feed end of the 2# ball mill (12) through a pumping pipeline. The first output end of the 3# cyclone (16) is connected to the direct flotation system through a pipeline. The second output end of the 3# cyclone (16) is connected to the feed end of the 2# ball mill (12) through a pipeline.

9. The system according to claim 8, characterized in that, The No. 2 ball mill (12) is filled with steel balls or steel segments with a diameter of 20~40mm for fine grinding operations.

10. The system according to claim 8, characterized in that, The feeding end of the ball mill (12) is connected to the pump pool (13) via a pipeline. The pump pool (13) is connected to the feed end of the sand pump (14) via a pipeline. The sand pump (14) is connected to the feed end of the hydrocyclone (16) via a pipeline.

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