Ore grinding classification system and method for reducing excessive grinding of ore grinding classification system

Abstract

The invention discloses a method and system for reducing excessive grinding of an ore grinding classification system. The method comprises the following steps: feeding an ore grinding and grading raw material into a high-frequency fine screen for screening treatment to obtain a high-frequency fine screen undersize product and a high-frequency fine screen oversize product; feeding oversize products of the high-frequency fine screen into a grading cyclone through a conveying pump for grading treatment to obtain primary grading cyclone settled sand and primary grading cyclone overflow; the primary classification hydrocyclone settled sand is fed into a ball mill for ore grinding treatment, ore pulp obtained after ore grinding is fed into a classification hydrocyclone through a conveying pump for classification treatment, and secondary classification hydrocyclone settled sand and secondary classification hydrocyclone overflow are obtained; and the overflow of the primary grading cyclone and / or the overflow of the secondary grading cyclone automatically flow back to the high-frequency fine screen and are mixed with the ore grinding grading raw materials fed in the next batch, and then screening treatment is conducted again. According to the method, mineral over-grinding can be reduced, the recovery rate is increased, the cost is reduced, and adaptability is high.

Description

Technical Field

[0001] This invention belongs to the field of mineral processing technology, specifically relating to a method for reducing over-grinding in a grinding and classification system and a grinding and classification system. Background Technology

[0002] Ilmenite in vanadium-titanium magnetite tailings has relatively large crystal size, with the -0.154mm particle size exhibiting a liberation degree as high as 95%. Theoretically, it can meet the requirements of subsequent beneficiation processes without excessive grinding, providing a basic foundation for efficient recovery. However, existing grinding and classification processes in the mineral processing field generally suffer from unreasonable design, resulting in low ilmenite resource recovery efficiency and significant waste.

[0003] On the one hand, the existing grinding and classification process has long adopted a "grind first, then screen" model. In this model, pre-classification is performed using a classifying hydrocyclone. However, the classification accuracy of the hydrocyclone is limited, and undissociated coarse particles are easily entrained in the overflow, while fine particles that have reached the qualified particle size are mixed in the underflow. The coarse particles need to be repeatedly ground in the ball mill to achieve the required dissociation, while the fine particles are over-ground during the circulating grinding process, forming a large amount of ineffective over-grinding products. At the same time, high-frequency fine screens are only used as end-of-line inspection and classification equipment and cannot separate qualified particle sizes before grinding. This results in a large amount of already dissociated ilmenite entering the ball mill along with the coarse particles, further exacerbating the over-grinding phenomenon.

[0004] On the other hand, over-grinding has triggered a series of chain reactions: over-grinded ilmenite particles are very likely to form slime (of which the content of -0.020mm particles often reaches 10%-15%). This slime is not only difficult to recover through existing beneficiation processes, but also pollutes the slurry system, damages the flotation environment, and leads to a significant increase in the consumption of flotation reagents. Ultimately, the actual recovery rate of ilmenite from the original ore is only 20%-36%, and titanium resources are not effectively utilized.

[0005] Therefore, existing technologies still need improvement. Summary of the Invention

[0006] Based on this, and addressing the shortcomings of the existing technology, a method and system for reducing over-grinding in a grinding and classification system are provided. Through a process of "priority screening, precise classification, and on-demand grinding," qualified particle sizes are pre-separated, preventing liberated minerals from entering the grinding cycle. This solves the technical problem of ilmenite becoming muddy during over-grinding in traditional processes, improves the recovery rate of the ilmenite system, and reduces operating costs.

[0007] To achieve the above objectives, the following technical solution is adopted: This invention provides a method for reducing over-grinding in a grinding and classification system, comprising the following steps: S101. The grinding and classifying raw materials are fed into a high-frequency fine screen for screening to obtain high-frequency fine screen undersize and high-frequency fine screen oversize; wherein, the high-frequency fine screen undersize is qualified particle size mineral and directly enters the next beneficiation process; S102. The material over the high-frequency fine screen is sent into a classifying hydrocyclone by a conveying pump for classification treatment, resulting in primary classifying hydrocyclone underflow and primary classifying hydrocyclone overflow. S103. The primary classifier underflow is fed into a ball mill for grinding. The slurry after grinding is then fed into a classifier hydrocyclone for classification, resulting in secondary classifier underflow and secondary classifier overflow. S104. The overflow from the primary classifier hydrocyclone and / or the overflow from the secondary classifier hydrocyclone is returned to the high-frequency fine screen by gravity, mixed with the next batch of grinding and classifying raw materials, and then screened again. Repeat steps S101-S103. The underflow from the secondary classifier hydrocyclone is sent to the ball mill for grinding. Repeat steps S103-S104.

[0008] In some embodiments, in step S102, the material over the high-frequency fine screen flows by gravity to the pump pool and is then sent to the classifying hydrocyclone by a transfer pump. In step S102, the pump pool is selected from either the ball mill discharge pump pool or an independent pump pool used in step S103. When the pump pool is the ball mill discharge pump pool, in step S103, the slurry after grinding flows by gravity to the ball mill discharge pump pool and is combined with the oversize material of the next batch of high-frequency fine screen before entering the classifying hydrocyclone for classification. When the pump pool is an independent pump pool, in step S103, the slurry after grinding flows by gravity to the ball mill discharge pump pool and is then sent to the classifying hydrocyclone by a conveying pump.

[0009] In some embodiments, the grinding and classification raw material is ilmenite from vanadium-titanium magnetite tailings, wherein the content of -0.80mm particle size is ≥90%, the content of -0.074mm particle size is 20%-80%, and the TiO2 grade is 3.5%-15%.

[0010] In some embodiments, the high-frequency fine screen has a screen aperture size of 0.074-0.21 mm, an opening rate of 25%-35%, a screen surface inclination angle of 15°-20°, a feed concentration of 20%-40%, and a screening efficiency of 75%-90%.

[0011] In some embodiments, the classifying hydrocyclone in step S102 and the classifying hydrocyclone in step S103 are the same classifying hydrocyclone or two independent classifying hydrocyclones; the classifying hydrocyclone is a flat-bottomed hydrocyclone with a sediment concentration of 60%-80%, an overflow concentration of 15%-40%, and a classification efficiency of 75%-88%.

[0012] In some embodiments, the grinding media of the ball mill are steel balls with a diameter of φ10-60mm, the grinding concentration of the ball mill is 60%-80%, and the content of -0.020mm over-grinding particles is ≤5%.

[0013] The present invention also provides a grinding and classification system that uses the method described above to reduce over-grinding for grinding. The grinding and classification system includes a high-frequency fine screen, a conveying pump, a classifying hydrocyclone, and a ball mill. The high-frequency fine screen includes a feed end for receiving grinding and classification raw materials, an undersize discharge end, and an oversize discharge end; the undersize discharge end is connected to the next separation process, and the oversize discharge end is connected to the classifying hydrocyclone. The sand outlet of the classifying hydrocyclone is connected to the feed inlet of the ball mill, and the overflow outlet of the classifying hydrocyclone is connected to the feed end of the high-frequency fine screen. The discharge port of the ball mill is connected to the classifying hydrocyclone or another classifying hydrocyclone; The connection between the high-frequency fine screen, the classifying hydrocyclone, and the ball mill forms a closed loop.

[0014] In some embodiments, the oversize discharge end is connected to the classifying hydrocyclone via a pump pool, and the discharge port of the ball mill is connected to the classifying hydrocyclone via a ball mill discharge pump pool; wherein, the pump pool is the ball mill discharge pump pool or an independent pump pool.

[0015] In some embodiments, when the discharge port of the ball mill is connected to the other classifying hydrocyclone, the overflow outlet of the other classifying hydrocyclone is connected to the feed end of the high-frequency fine screen.

[0016] In some embodiments, the ilmenite recovery rate of the grinding and classification system is ≥42%, and the amount of over-grinded minerals in the grinding and classification process is reduced by 30%-50%; the cyclic load of the closed loop is 150%-250%.

[0017] The present invention has the following beneficial technical effects: The present invention discloses a method for reducing over-grinding in a grinding and classification system, and a grinding and classification system thereof: Significantly reduces over-grinding: Through "high-frequency fine screening with priority screening", more than 85% of qualified particles are separated in advance to prevent them from entering the grinding cycle; the classifying hydrocyclone accurately classifies and reduces fine sand entrainment, and the ball mill only grinds coarse particles, so that the content of -0.020mm over-grinding particles is reduced from 10%-15% in the traditional process to ≤5%, and the loss of ilmenite mudification is reduced by more than 60%.

[0018] Improve ilmenite recovery rate: Avoid over-grinding which makes ilmenite difficult to recover, and increase the system recovery rate of raw ore from 20%-36% in the existing process to ≥42%, significantly improving resource utilization efficiency.

[0019] Cost reduction: Early separation of qualified particle size reduces the circulating load of the ball mill by 20%-30% and the grinding power consumption by 10%-20%; reduced over-grinding slime reduces flotation reagent consumption by 25%-35% and overall operating costs by 18%-28%.

[0020] High process adaptability: It can be directly applied to titanium beneficiation production lines of vanadium-titanium magnetite, and can also be adapted to grinding and classification of other easily over-grindable oxidized ores (such as tin ore and tungsten ore). The equipment is simple to modify and does not require a large amount of new investment, making it suitable for upgrading and transforming existing beneficiation plants. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 A schematic diagram of the process flow of an existing grinding and classification system; Figure 2 This is a schematic diagram of a grinding and classification system that can reduce over-grinding according to an embodiment of the present invention; Figure 3 A schematic diagram of a grinding and classification system capable of reducing over-grinding according to another embodiment of the present invention; Figure 4 This is a flowchart illustrating a method for reducing over-grinding in a grinding and classification system according to an embodiment of the present invention. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be further described in detail below with reference to specific examples and the accompanying drawings.

[0024] It should be understood that the embodiments of the invention shown in the exemplary embodiments are merely illustrative. Although only a few embodiments have been described in detail in this invention, those skilled in the art will readily recognize that various modifications are possible without substantially departing from the teachings of the invention. Accordingly, all such modifications should be included within the scope of the invention. Other substitutions, modifications, variations, and deletions can be made to the design, operating conditions, and parameters of the following exemplary embodiments without departing from the spirit of the invention.

[0025] Figure 1This is a schematic diagram of an existing grinding and classification process. The raw material first enters a classifying hydrocyclone for pre-classification. After separation by the hydrocyclone, an overflow containing fine particles and a settling sand containing coarse particles are obtained. The settling sand is then fed into a ball mill for grinding. The ground slurry, along with the overflow from the classifying hydrocyclone, flows into a high-frequency fine screen for final classification. The qualified particle size passing through the high-frequency fine screen enters the next beneficiation process, completing the entire grinding and classification process. Because this process uses a "classification before grinding, high-frequency fine screen after" design, it cannot separate qualified particle sizes in advance, easily leading to over-grinding of fine particles during circulation, resulting in over-grinding, mudding, and low recovery rates.

[0026] To address the aforementioned technical problems, a first aspect of the present invention provides a grinding and classification system capable of reducing over-grinding. A second aspect of the present invention provides a method for reducing over-grinding in a grinding and classification system.

[0027] Figure 2-4 The diagram shows a schematic flow chart of a grinding and classifying system according to an embodiment of the present invention, as well as a schematic flow chart of the method.

[0028] like Figure 4 As shown, the method for reducing over-grinding in this grinding and classification system may include the following steps: S101. The grinding and classifying raw materials are fed into a high-frequency fine screen for screening to obtain high-frequency fine screen undersize and high-frequency fine screen oversize; wherein, the high-frequency fine screen undersize is qualified particle size mineral and directly enters the next beneficiation process; S102. The material over the high-frequency fine screen is sent into a classifying hydrocyclone by a conveying pump for classification treatment, resulting in primary classifying hydrocyclone underflow and primary classifying hydrocyclone overflow. S103. The primary classifier underflow is fed into a ball mill for grinding. The slurry after grinding is then fed into a classifier hydrocyclone for classification, resulting in secondary classifier underflow and secondary classifier overflow. S104. The overflow from the primary classifier hydrocyclone and / or the overflow from the secondary classifier hydrocyclone is returned to the high-frequency fine screen by gravity, mixed with the next batch of grinding and classifying raw materials, and then screened again. Repeat steps S101-S103. The underflow from the secondary classifier hydrocyclone is sent to the ball mill for grinding. Repeat steps S103-S104.

[0029] In a preferred embodiment of the present invention, the underflow from the secondary classifier hydrocyclone is fed into a ball mill for grinding to achieve the individual separation of mineral particles. The slurry after grinding flows by gravity to the ball mill discharge pump pool.

[0030] In a preferred embodiment of the present invention, in step S102, the material oversize from the high-frequency fine screen flows by gravity to the pump pool and is then sent to the classifying hydrocyclone by a conveying pump. In step S102, the pump pool is selected from either the ball mill discharge pump pool or an independent pump pool used in step S103. When the pump pool is the ball mill discharge pump pool, in step S103, the slurry after grinding flows by gravity to the ball mill discharge pump pool and is combined with the oversize material of the next batch of high-frequency fine screen before entering the classifying hydrocyclone for classification. When the pump pool is an independent pump pool, in step S103, the slurry after grinding flows by gravity to the ball mill discharge pump pool and is then sent to the classifying hydrocyclone by a conveying pump.

[0031] In a preferred embodiment of the present invention, the grinding and classification raw material is ilmenite from the iron tailings of vanadium-titanium magnetite beneficiation, wherein the content of -0.80mm particle size is ≥90%, the content of -0.074mm particle size is 20%-80%, and the TiO2 grade is 3.5%-15%.

[0032] In a preferred embodiment of the present invention, the high-frequency fine screen has a screen aperture size of 0.074-0.21 mm, an opening rate of 25%-35%, a screen surface inclination angle of 15°-20°, a feed concentration of 20%-40%, and a screening efficiency of 75%-90%.

[0033] Specifically, high-frequency fine screening prioritizes the following: The grinding and classifying raw material (vanadium-titanium magnetite tailings, -0.80mm particle size ≥ 90%) is fed into the high-frequency fine screen. The high-frequency fine screen uses a screen with an aperture size of 0.074-0.21mm and a screen inclination angle of 15°-20°. Qualified particles pass directly through the screen to form undersize material, which enters subsequent processes; coarse particles that do not meet the qualified particle size form oversize material, which flows by gravity into the pump tank.

[0034] In a preferred embodiment of the present invention, the classifying hydrocyclone in step S102 and the classifying hydrocyclone in step S103 are the same classifying hydrocyclone or two independent classifying hydrocyclones; the classifying hydrocyclone is a flat-bottomed hydrocyclone with a sediment concentration of 60%-80%, an overflow concentration of 15%-40%, and a classification efficiency of 75%-88%.

[0035] Specifically, the classifying hydrocyclone provides precise classification: High-frequency fine screen oversize material is fed separately or mixed with ball mill discharge via a transfer pump into the flat-bottomed hydrocyclone. The classifying hydrocyclone achieves a sediment concentration of 60%-80% and an overflow concentration of 12%-40%. This hydrocyclone uses a dynamic fluidized bed at the bottom to prevent fine particles from entering the sediment. It features a simple structure, large processing capacity, reduced turbulence within the cylinder, and reduced short-circuit flow, effectively preventing over-grinding caused by "fine particles trapped in sediment."

[0036] like Figure 2In one embodiment shown, the classifying hydrocyclone in step S102 and the classifying hydrocyclone in step S103 are the same classifying hydrocyclone. For example, the first batch of oversize material from the high-frequency fine screen is pumped into the classifying hydrocyclone for classification, resulting in primary classifying hydrocyclone underflow and primary classifying hydrocyclone overflow. The primary classifying hydrocyclone underflow then enters a ball mill for grinding, while the primary classifying hydrocyclone overflow returns to the high-frequency fine screen for further screening and repeats the subsequent steps. The slurry obtained from the primary classifying hydrocyclone underflow grinding in the ball mill is returned to the same classifying hydrocyclone for classification, resulting in secondary classifying hydrocyclone underflow and secondary classifying hydrocyclone overflow. The secondary classifying hydrocyclone overflow returns to the high-frequency fine screen for further screening and repeats the subsequent steps. The secondary classifying hydrocyclone underflow then returns to the ball mill for further grinding and repeats the subsequent steps. When processing multiple batches, the primary classifying hydrocyclone overflow of the next batch and the secondary classifying hydrocyclone overflow of the previous batch can be mixed and returned to the high-frequency fine screen for further screening and repeats the subsequent steps.

[0037] like Figure 3 In another embodiment shown, the classifying hydrocyclones in step S102 and S103 are two independent classifying hydrocyclones. The classifying hydrocyclone in step S102 is called Classifying Hydrocyclone I, and the classifying hydrocyclone in step S103 is called Classifying Hydrocyclone II. For example, the first batch of oversize material from the high-frequency fine screen is pumped into Classifying Hydrocyclone I for classification to obtain primary classifying hydrocyclone underflow and primary classifying hydrocyclone overflow. The primary classifying hydrocyclone underflow enters the ball mill for grinding, and the primary classifying hydrocyclone overflow returns to the high-frequency fine screen for screening and repeats the subsequent steps. The slurry obtained from the primary classifying hydrocyclone underflow entering the ball mill for grinding enters Classifying Hydrocyclone II for classification to obtain secondary classifying hydrocyclone underflow and secondary classifying hydrocyclone overflow. The secondary classifying hydrocyclone overflow returns to the high-frequency fine screen for screening and repeats the subsequent steps. The secondary classifying hydrocyclone underflow returns to the ball mill again for grinding and repeats the subsequent steps.

[0038] In a preferred embodiment of the present invention, the grinding media of the ball mill is steel balls with a diameter of φ10-60mm, the grinding concentration of the ball mill is 60%-80%, and the content of -0.020mm over-grinding particles is ≤5%.

[0039] Specifically, the ball mill performs on-demand grinding: the underflow from the classifier hydrocyclone is fed into the ball mill, and φ10-60mm steel balls are used as the grinding media. Grinding is carried out under the condition of 60%-80% grinding concentration, and only coarse particles are ground in a targeted manner to achieve mineral individual liberation (-0.154mm particle size individual liberation degree ≥95%). The mill discharge enters the ball mill discharge pump pool to enter the next round of classification cycle, avoiding "blind fine grinding".

[0040] The grinding and classification system uses the method of reducing over-grinding as described above for grinding. The grinding and classification system includes a high-frequency fine screen, a conveying pump, a classifying hydrocyclone, and a ball mill. The high-frequency fine screen includes a feed end for receiving grinding and classification raw materials, an undersize discharge end, and an oversize discharge end; the undersize discharge end is connected to the next separation process, and the oversize discharge end is connected to the classifying hydrocyclone. The sand outlet of the classifying hydrocyclone is connected to the feed inlet of the ball mill, and the overflow outlet of the classifying hydrocyclone is connected to the feed end of the high-frequency fine screen. The discharge port of the ball mill is connected to a classifying hydrocyclone or another classifying hydrocyclone; The connection between the high-frequency fine screen, the classifying hydrocyclone, and the ball mill forms a closed loop.

[0041] like Figure 2 As shown, the grinding and classification raw materials first enter a high-frequency fine screen for priority screening. The qualified particle size minerals under the screen directly enter the next beneficiation process, while the coarse particles on the screen flow by gravity into the pump pool. The material in the pump pool is sent to the classifying hydrocyclone for precise classification by a conveying pump. The resulting sand is sent to a ball mill for targeted grinding. The slurry after grinding is returned to the ball mill discharge pump pool and, together with the coarse particles on the subsequent screens, either separately or in combination, re-enters the classifying hydrocyclone for classification. The overflow of the classifying hydrocyclone flows by gravity back to the high-frequency fine screen, mixes with the newly fed grinding and classification raw materials, and is then screened again, forming a closed loop.

[0042] In a preferred embodiment of the present invention, the discharge end of the screen material is connected to the classifying hydrocyclone via a pump pool, and the discharge port of the ball mill is connected to the classifying hydrocyclone via a ball mill discharge pump pool; wherein, the pump pool is a ball mill discharge pump pool or an independent pump pool.

[0043] In a preferred embodiment of the present invention, when the discharge port of the ball mill is connected to another classifying hydrocyclone, the overflow outlet of the other classifying hydrocyclone is connected to the feed end of the high-frequency fine screen.

[0044] In a preferred embodiment of the present invention, the ilmenite system recovery rate of the grinding and classification system is ≥42%, and the amount of over-grinded minerals in the grinding and classification process is reduced by 30%-50%.

[0045] In a preferred embodiment of the present invention, the cyclic load of the closed-loop circuit is 150%-250%.

[0046] Closed-loop circulation optimization: The overflow from the classifying hydrocyclone flows back to the high-frequency fine screen by gravity, mixes with the newly fed grinding and classification raw materials, and is then re-screened. This circulation can recover a small amount of qualified particles that have not been screened in the overflow, while avoiding over-grinding caused by the accumulation of fine particles in the overflow. The circulation load rate is controlled at 150%-250% to ensure stable process operation.

[0047] The present invention will be further illustrated by the following examples.

[0048] Example 1 The iron tailings from vanadium-titanium magnetite ore beneficiation at a beneficiation plant in the Panxi region, after being pre-enriched by strong magnetic field, are used as raw material for grinding and classification. The properties of the raw material are as follows: The content of -0.80mm particle size is 92%, the content of -0.074mm particle size is 44%, and the TiO2 grade is 9.5%. The grinding and classification are carried out using the process described in this invention. The specific steps and parameters are as follows: High-frequency fine screening is used for priority screening: a high-frequency fine screen with a screen aperture size of 0.18 mm, a vibration frequency of 2000 r / min, a screen surface inclination angle of 18°, and a feed concentration of 30% is selected. After screening, the undersize material (qualified particle size) and the oversize material (coarse particles) are obtained.

[0049] Precise classification using a classifying hydrocyclone: ​​A flat-bottomed classifying hydrocyclone (model FX350-GX-B) is selected, with a classification particle size boundary of 0.15mm and a feed pressure of 0.25MPa.

[0050] Ball mill for on-demand grinding: MQY3245 ball mill is selected, with steel ball diameter φ40mm, filling rate 40%, and grinding concentration 70.5%.

[0051] Closed-loop operation: overflow from the classifying hydrocyclone is returned to the high-frequency fine screen, with a circulation load rate of 200%.

[0052] Compared with the existing process, the advantages of Example 1 are as follows: the content of over-grinding particles (-0.020mm) is reduced from 12.5% ​​to 4.2%, a reduction of 66.4%; the recovery rate of ilmenite system is increased from 36.1% to 43.3%, an increase of 7.2 percentage points; and the cost of flotation reagents is reduced to 125 yuan / t, a decrease of 26.6%.

[0053] Example 2 The iron tailings from vanadium-titanium magnetite ore beneficiation at a beneficiation plant in the Panxi region, after being pre-enriched by strong magnetic field, are used as raw material for grinding and classification. The properties of the raw material are as follows: - 0.80mm particle size content 91%, -0.074mm particle size content 42%, TiO2 grade 9.2%. Grinding and classification are performed using the process described in this invention. The specific steps and parameters are as follows: High-frequency fine screening is used: a high-frequency fine screen with a screen aperture size of 0.074 mm, a vibration frequency of 2200 r / min, a screen surface inclination angle of 15°, and a feed concentration of 26% is selected. After screening, the undersize material (qualified particle size) and the oversize material (coarse particles) are obtained.

[0054] Precise classification using a classifying hydrocyclone: ​​A flat-bottomed classifying hydrocyclone (model FX350-GX-B) is selected, with a classification particle size boundary of 0.15mm and a feed pressure of 0.20MPa.

[0055] Ball mill for on-demand grinding: MQY3245 ball mill is selected, with steel ball diameter φ10mm, filling rate 38%, and grinding concentration 68%.

[0056] Closed-loop operation: The overflow from the classifying hydrocyclone is returned to the high-frequency fine screen, with a circulation load rate of 180%.

[0057] Compared with the existing process, the advantages of this Example 2 are as follows: the content of over-grinding particles (-0.020mm) is reduced from 12.3% to 4.8%, a reduction of 61.0%; the recovery rate of ilmenite system is increased from 35.8% to 42.1%, an increase of 6.3 percentage points; and the cost of flotation reagents is reduced to 132 yuan / t, a decrease of 22.4%.

[0058] Example 3 The iron tailings from vanadium-titanium magnetite ore beneficiation at a beneficiation plant in the Panxi region, after being pre-enriched by strong magnetic field, are used as raw material for grinding and classification. The properties of the raw material are as follows: The content of -0.80mm particle size is 93%, the content of -0.074mm particle size is 46%, and the TiO2 grade is 9.8%. The grinding and classification are carried out using the process described in this invention. The specific steps and parameters are as follows: High-frequency fine screening is used: a high-frequency fine screen with a screen mesh size of 0.18+0.21mm is selected, the vibration frequency is 1800r / min, the screen surface inclination angle is 20°, and the feed concentration is 35%. After screening, the undersize material (qualified particle size) and the oversize material (coarse particles) are obtained.

[0059] Precise classification using a classifying hydrocyclone: ​​A flat-bottomed classifying hydrocyclone (model FX350-GX-B) is selected, with a classification particle size boundary of 0.18mm and a feed pressure of 0.30MPa.

[0060] Ball mill for on-demand grinding: MQY3245 ball mill is selected, with steel ball diameter φ60mm, filling rate 42%, and grinding concentration 78%.

[0061] Closed-loop operation: The overflow from the classifying hydrocyclone is returned to the high-frequency fine screen, with a circulation load rate of 250%.

[0062] Compared with the existing process, the advantages of this Example 3 are as follows: the content of over-grinding particles (-0.020mm) is reduced from 12.7% to 4.5%, a reduction of 64.6%; the recovery rate of ilmenite system is increased from 36.3% to 42.8%, an increase of 6.5 percentage points; and the cost of flotation reagents is reduced to 128 yuan / t, a decrease of 24.2%.

[0063] The above embodiments demonstrate that the method and system of the present invention can effectively reduce over-grinding of ilmenite, significantly improve the recovery rate, and reduce operating costs. They are applicable to the grinding and classification of vanadium-titanium magnetite and other easily over-grindable minerals, and have good prospects for industrial application.

[0064] The above are exemplary embodiments disclosed in this invention. However, it should be noted that various changes and modifications can be made without departing from the scope of the embodiments of this invention as defined by the claims. Although the elements disclosed in the embodiments of this invention may be described or claimed individually, they may be understood as multiple unless explicitly limited to a singular number.

[0065] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention (including the claims) is limited to these examples. Within the framework of the invention, technical features of the above embodiments or different embodiments can be combined, and many other variations of different aspects of the invention exist, which are not provided in the details for the sake of brevity. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the invention should be included within the protection scope of the invention.

Claims

1. A method for reducing over-grinding in a grinding and classification system, characterized in that, Includes the following steps: S101. The grinding and classifying raw materials are fed into a high-frequency fine screen for screening to obtain high-frequency fine screen undersize and high-frequency fine screen oversize; wherein, the high-frequency fine screen undersize is qualified particle size mineral and directly enters the next beneficiation process; S102. The material over the high-frequency fine screen is sent into a classifying hydrocyclone by a conveying pump for classification treatment, resulting in primary classifying hydrocyclone underflow and primary classifying hydrocyclone overflow. S103. The primary classifier underflow is fed into a ball mill for grinding. The slurry after grinding is then fed into a classifier hydrocyclone for classification, resulting in secondary classifier underflow and secondary classifier overflow. S104. The overflow from the primary classifier hydrocyclone and / or the overflow from the secondary classifier hydrocyclone is returned to the high-frequency fine screen by gravity, mixed with the next batch of grinding and classifying raw materials, and then screened again. Repeat steps S101-S103. The underflow from the secondary classifier hydrocyclone is sent to the ball mill for grinding. Repeat steps S103-S104.

2. The method for reducing over-grinding in the grinding and classification system according to claim 1, characterized in that, In step S102, the material oversize from the high-frequency fine screen flows by gravity to the pump pool and is then sent to the classifying hydrocyclone by a transfer pump. In step S102, the pump pool is selected from either the ball mill discharge pump pool or an independent pump pool used in step S103. When the pump pool is the ball mill discharge pump pool, in step S103, the slurry after grinding flows by gravity to the ball mill discharge pump pool and is combined with the oversize material of the next batch of high-frequency fine screen before entering the classifying hydrocyclone for classification. When the pump pool is an independent pump pool, in step S103, the slurry after grinding flows by gravity to the ball mill discharge pump pool and is then sent to the classifying hydrocyclone by a conveying pump.

3. The method for reducing over-grinding in the grinding and classification system according to claim 1, characterized in that, The grinding and classification raw material is ilmenite from the iron tailings of vanadium-titanium magnetite beneficiation, wherein the content of -0.80mm particle size is ≥90%, the content of -0.074mm particle size is 20%-80%, and the TiO2 grade is 3.5%-15%.

4. The method for reducing over-grinding in the grinding and classification system according to claim 1, characterized in that, The high-frequency fine screen has a screen aperture size of 0.074-0.21 mm, an opening rate of 25%-35%, a screen surface inclination angle of 15°-20°, a feed concentration of 20%-40%, and a screening efficiency of 75%-90%.

5. The method for reducing over-grinding in the grinding and classification system according to claim 1, characterized in that, The classifying hydrocyclone in step S102 and the classifying hydrocyclone in step S103 are either the same classifying hydrocyclone or two independent classifying hydrocyclones; the classifying hydrocyclone is a flat-bottomed hydrocyclone with a sediment concentration of 60%-80%, an overflow concentration of 15%-40%, and a classification efficiency of 75%-88%.

6. The method for reducing over-grinding in the grinding and classification system according to claim 1, characterized in that, The grinding media of the ball mill are steel balls with a diameter of φ10-60mm. The grinding concentration of the ball mill is 60%-80%, and the content of over-grinding particles of -0.020mm is ≤5%.

7. A grinding and classification system, characterized in that, The grinding and classification system is performed using the method for reducing over-grinding as described in any one of claims 1-6, wherein the grinding and classification system includes a high-frequency fine screen, a conveying pump, a classifying hydrocyclone, and a ball mill. The high-frequency fine screen includes a feed end for receiving grinding and classification raw materials, an undersize discharge end, and an oversize discharge end; the undersize discharge end is connected to the next separation process, and the oversize discharge end is connected to the classifying hydrocyclone. The sand outlet of the classifying hydrocyclone is connected to the feed inlet of the ball mill, and the overflow outlet of the classifying hydrocyclone is connected to the feed end of the high-frequency fine screen. The discharge port of the ball mill is connected to the classifying hydrocyclone or another classifying hydrocyclone; The connection between the high-frequency fine screen, the classifying hydrocyclone, and the ball mill forms a closed loop.

8. The grinding and classification system according to claim 7, characterized in that, The discharge end of the screen material is connected to the classifying hydrocyclone through a pump pool, and the discharge port of the ball mill is connected to the classifying hydrocyclone through a ball mill discharge pump pool; wherein, the pump pool is the ball mill discharge pump pool or an independent pump pool.

9. The grinding and classification system according to claim 7, characterized in that, When the discharge port of the ball mill is connected to the other classifying hydrocyclone, the overflow outlet of the other classifying hydrocyclone is connected to the feed end of the high-frequency fine screen.

10. The grinding and classification system according to claim 7, characterized in that, The ilmenite recovery rate of the grinding and classification system is ≥42%, and the amount of over-grinded minerals in the grinding and classification process is reduced by 30%-50%; the cyclic load of the closed loop is 150%-250%.

Images