A method for optimizing the axial spatial distribution of grinding media inside a drum mill based on liner modification design

Abstract

The present invention relates to a method for optimizing the axial spatial distribution of grinding media inside a drum mill based on a liner modification design, and belongs to the field of grinding optimization technology. A process survey is conducted on the grinding section of a concentrator to obtain the material particle size composition of each sampling point; the panel angle of the drum mill liner is modified and designed: the panel angle of the liner design is 45°-90°; the drum mill liner is divided into 2-4 sections for axial combination and installation to obtain drum mill liners with different section panel angle combinations, and then the drum mill liners with different section panel angle combinations are simulated based on the discrete element method, and the best combination of the axial spatial distribution of grinding media inside the drum mill is selected based on the characteristics of coarse particles at the feeding end and fine particles at the discharging end. The present invention optimizes the axial spatial distribution of steel balls by adjusting the axial distribution of different liner structures, thereby achieving the purpose of improving energy utilization efficiency and reducing over-crushing of minerals.

Description

Technical Field

[0001] The invention relates to a method for optimizing the axial spatial distribution of grinding media inside a drum mill based on a liner modification design, and belongs to the technical field of grinding optimization. Background Art

[0002] Grinding is the core element in achieving selective mineral separation. To fully separate useful minerals from gangue minerals, efficient selective grinding is essential. Grinding is a crucial pre-processing step before mineral processing. On the one hand, the mineral grinding process consumes enormous amounts of energy and steel. According to statistics, grinding energy consumption in my country accounts for approximately 1.15% of the nation's total energy consumption, and steel consumption accounts for over 50% of a beneficiation plant's total steel consumption. On the other hand, the characteristics of the ground product largely determine the performance of subsequent separation processes. Therefore, reducing energy and steel consumption during drum mill operation and optimizing the characteristics of the ground product are hot topics in current grinding research.

[0003] Grinding media is the energy transmitter in the grinding process and the agent for ore crushing. Grinding media is one of the most important factors affecting grinding energy consumption, steel consumption and the characteristics of grinding products. The grinding efficiency of the drum mill is affected by the shape, size, ratio, movement form and axial spatial distribution of the grinding media inside the drum mill, among which the influence of the axial spatial distribution of the media is the most significant. Engineering practice has shown that using large-sized media for impact crushing of coarse particles and small-sized media for grinding of fine particles can achieve selective grinding and thus avoid over-crushing of minerals. Wang Yubin's research found that the axial spatial distribution of minerals inside the drum mill is characterized by coarse particles at the feed end and fine particles at the discharge end, and proposed micro-stage grinding technology, which is of great significance for increasing the processing capacity of the drum mill and improving the characteristics of grinding products. Two technologies have been developed domestically and internationally to address the axial spatial distribution of minerals within a drum mill: one involves adding baffles to the mill, dividing it into several compartments with varying media sizes, allowing large balls to impact large ores while small balls grind smaller ones. The other involves the development of the Harding drum mill, which features a cylindrical feed end and a conical discharge end, optimizing the spatial distribution of steel balls. While both technologies have reduced over-crushing and increased mill throughput to a certain extent, they present numerous challenges in manufacturing, maintenance, and ball replenishment, hindering their widespread adoption in industrial production.

[0004] The liner of a drum mill not only protects the mill cylinder but also plays a role in ore grinding. On the one hand, it protects the mill cylinder from the intense impact, grinding, and chemical corrosion of the grinding media and ore. On the other hand, it transfers the energy of the mill cylinder to the grinding media and ore, enabling them to achieve the grinding effect through movement. The shape of the drum mill liner has a significant impact on the mill's throughput, operating rate, liner service life, and energy efficiency. Domestic and foreign scholars have achieved a lot of results in the study of liner shape: Cleary conducted numerical simulation analysis on ball mill through discrete element method, obtained the collision energy spectrum of the interaction between each part, and determined the energy distribution of the mill; Kmishra conducted simulation research on mill through discrete element method, analyzed the wear of liner and grinding behavior of ore; Zhao Yuan studied the effect of particle shape on grinding based on discrete element method, and quantitatively analyzed the influence of particle shape on load characteristics; Cai Gaipin used discrete element software to establish a semi-autogenous ball mill grinding simulation model, and studied the influence of liner height on the grinding efficiency of semi-autogenous mill, so as to improve the grinding capacity of mill.

[0005] In summary, most researchers have focused on optimizing liner shape or ball gradation alone. Few have combined liner modification with ball gradation design, and even fewer have delved into the influence of liner shape parameters on the axial spatial distribution of balls. This paper systematically investigates the effects of different liner structure combinations on the axial spatial distribution of balls using the discrete element method, which has important research value for improving the grinding efficiency of drum mills. Summary of the Invention

[0006] To address the aforementioned problems and shortcomings of the existing technology, the present invention provides a method for optimizing the axial spatial distribution of grinding media within a drum mill based on modified liner design. By adjusting the axial distribution of different liner structures, the present invention optimizes the axial spatial distribution of steel balls, thereby improving energy efficiency and reducing over-crushing of minerals. This method provides new insights and guidance for efficient and selective grinding, and is of great significance. The present invention is implemented through the following technical solutions.

[0007] A method for optimizing the axial spatial distribution of grinding media inside a drum mill based on liner modification design, the steps comprising:

[0008] (1) Conduct a process inspection of the grinding section of the concentrator: take samples at the feed belt, cyclone sand settling nozzle, and the feed and discharge ends of the drum mill to obtain the material particle size composition at each sampling point, and analyze the characteristics of coarse particles at the feed end and fine particles at the discharge end;

[0009] (2) Redesign the panel angle of the drum mill liner: the panel angle of the liner design is 45°-90°;

[0010] (3) The drum mill liner is divided into 2-4 sections for axial combination installation. The drum mill liners of different sections are axially combined through the panel angle of step (2) to obtain drum mill liners with different section panel angle combinations. Then, the drum mill liners with different section panel angle combinations are simulated based on the discrete element method. Based on the characteristics of coarse particles at the feeding end and fine particles at the discharging end in step (1), the best combination for optimizing the axial spatial distribution of the grinding media inside the drum mill is selected.

[0011] In step (3), the length of the drum mill liner is 4.8-12m.

[0012] In step (3), the drum mill liner with different panel angle combinations is simulated based on the discrete element method to obtain the axial spatial distribution diagram of steel balls of different sizes. The steel ball size that is consistent with the characteristic of coarse particles at the feeding end and fine particles at the discharging end in step (1) is the optimal combination of the axial spatial distribution of the grinding media inside the drum mill.

[0013] The beneficial effects of the present invention are:

[0014] (1) The present invention optimizes the axial spatial distribution of the grinding media inside the mill, thereby achieving the purpose of increasing the mill processing capacity and improving the characteristics of the grinding product;

[0015] (2) The present invention studies the influence of different liner combinations on the axial spatial distribution characteristics of steel balls by means of numerical simulation, and quantitatively analyzes the mass distribution law of steel balls of various sizes in each section of the mill. By combining different liner structures, the present invention achieves the same effect as foreign special technologies (dividing the mill into several compartments and Harding mill) while reducing the application cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a process flow chart of the present invention;

[0017] Figure 2 It is a schematic diagram of the lining plate structure of the present invention at different panel angles;

[0018] Figure 3 Schematic diagrams of axial combinations of liner plates with different panel angles according to the present invention, wherein (a) is a 75°-75°-75°-75° combination, (b) is a 75°-75°-45°-45° combination, (c) is a 90°-75°-45°-45° combination, and (d) is a 90°-75°-75°-45° combination;

[0019] Figure 4It is a schematic diagram of the axial spatial distribution of steel balls of different sizes in the axial combinations of liners with different panel angles of the present invention, where (a) is a 75°-75°-75°-75° combination, (b) is a 90°-75°-45°-45° combination, (c) is a 90°-75°-75°-45° combination, and (d) is a 75°-75°-45°-45° combination. DETAILED DESCRIPTION

[0020] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. Example

[0021] like Figure 1 As shown, the method for optimizing the axial spatial distribution of grinding media inside a drum mill based on liner modification design comprises the following steps:

[0022] (1) The grinding process of the concentrator was investigated: samples were taken and screened at the feed belt, cyclone sand settling nozzle, and the feed and discharge ends of the drum mill to obtain the material particle size composition at each sampling point. The material particle size composition is shown in Table 1.

[0023]

[0024] As shown in Table 1, the axial spatial distribution of minerals inside the drum mill shows that the particles are coarse at the feed end and fine at the discharge end. Therefore, more large balls are needed at the feed end and more small balls are needed at the discharge end.

[0025] (2) The panel angle of the drum mill liner was modified and designed: the panel angles of the liner were designed to be 45°, 75°, and 90°; the supplementary ratio used by the concentrator was m (Φ40): m (Φ30): m (Φ20) = 1:1:1, the speed of the tube mill is 75%, the length of the tube mill is 8m; the tube mill liner is a T-shaped liner with a height of 15mm, and the panel angles are 45°, 75°, and 90°. The tube mill liner model is as follows Figure 2 As shown;

[0026] (3) The drum mill liner is divided into four sections for axial assembly and installation. The drum mill liners of different sections are axially assembled according to the panel angles of step (2) to obtain drum mill liners with different section panel angle combinations. The test scheme for different section panel angle combinations is shown in Table 2.

[0027]

[0028] Schematic diagram of axial combination of liner plates with different panel angles Figure 3 As shown, from Figure 3It can be seen that Option 1: 75°-75°-75°-75° combination, means that the first section of the drum mill liner (length is 2m) has a panel angle of 75°, the second section of the drum mill liner (length is 2m) has a panel angle of 75°, the third section of the drum mill liner (length is 2m) has a panel angle of 75° and the third section of the drum mill liner (length is 2m) has a panel angle of 75°, which are axially combined and installed together.

[0029] Option 2: 75°-75°-45°-45° combination, which means that the first section of the drum mill liner (length is 2m) has a panel angle of 75°, the second section of the drum mill liner (length is 2m) has a panel angle of 75°, the third section of the drum mill liner (length is 2m) has a panel angle of 45°, and the third section of the drum mill liner (length is 2m) has a panel angle of 45°, which are axially combined and installed together.

[0030] Option 3: 90°-75°-45°-45° combination, which means that the first section of the drum mill liner (length is 2m) has a panel angle of 90°, the second section of the drum mill liner (length is 2m) has a panel angle of 75°, the third section of the drum mill liner (length is 2m) has a panel angle of 45°, and the third section of the drum mill liner (length is 2m) has a panel angle of 45°, which are axially combined and installed together.

[0031] Option 4: 90°-75°-75°-45° combination, which means that the first section of the drum mill liner (length is 2m) has a panel angle of 90°, the second section of the drum mill liner (length is 2m) has a panel angle of 75°, the third section of the drum mill liner (length is 2m) has a panel angle of 75° and the third section of the drum mill liner (length is 2m) has a panel angle of 45°, which are axially combined and installed together.

[0032] Then, based on the discrete element method, the drum mill liner with different segment panel angle combinations is simulated. The simulation parameters are shown in Table 3.

[0033]

[0034] Based on the discrete element method, the liner of the drum mill with different panel angle combinations is simulated to obtain the axial spatial distribution diagram of steel balls of different sizes. The axial spatial distribution diagram of steel balls of different sizes is shown in the figure. Figure 4 As shown,

[0035] Figure 4 Small and medium balls are 40 mm steel balls, medium balls are 60 mm steel balls, and large balls are 80 mm steel balls. Figure 4 (a) It can be seen that the 75°-75°-75°-75° liner combination causes the large and medium balls to converge toward the center, while the small balls disperse toward the two ends. Figure 4(b) shows the spatial distribution of steel balls under the 90°-75°-45°-45° liner combination. It can be clearly seen that the large and medium balls are concentrated at the 90° face angle, with a mass fraction of 78.50%, while the small balls are concentrated at the 45° face angle, with a mass fraction of 47.95%. Figure 4 (c) shows the distribution of steel balls under the 90°-75°-75°-45° liner combination. It can be seen that the steel balls are distributed more evenly in the first three sections, while the proportion of small balls in the fourth section is higher, accounting for 53.49%. Figure 4 (d) shows the effect of the 75°-75°-45°-45° liner combination on the ball size distribution. As can be seen from the figure, large and medium balls are mainly concentrated in the second section, accounting for 81.53%.

[0036] From the above analysis, we can see that different combinations of liners in the drum mill will significantly affect the spatial distribution of steel ball sizes. Different liner combinations correspond to specific steel ball spatial distribution states. Therefore, the spatial distribution of steel balls can be controlled by optimizing the liner combination. Production practice shows that the size of the ore at the feed end of the drum mill is larger, and the size of the ore at the discharge end is smaller. In order to achieve the selective grinding effect of large balls impacting large ores and small balls grinding small ores, it is necessary to arrange the liners scientifically and reasonably. Figure 4 It can be seen that compared with the 75°-75°-75°-75° liner combination, the 90°-75°-45°-45° liner combination can better realize the large balls concentrated at the feeding end and the small balls distributed at the discharging end, thereby achieving efficient selective grinding.

[0037] The above describes the specific embodiments of the present invention in detail with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Various changes can be made within the knowledge of ordinary technicians in this field without departing from the scope of the present invention.

Claims

1. A method for optimizing the axial spatial distribution of grinding media inside a drum mill based on liner modification design, characterized by the following steps: include: (1) Conduct a process inspection of the grinding section of the concentrator: take samples at the feed belt, cyclone sand settling nozzle, and the feed and discharge ends of the drum mill to obtain the material particle size composition at each sampling point, and analyze the characteristics of coarse particles at the feed end and fine particles at the discharge end; (2) Redesign the panel angle of the drum mill liner: the panel angle of the liner design is 45°-90°; (3) The drum mill liner is divided into 2-4 sections for axial combination installation. The drum mill liners of different sections are axially combined through the panel angle of step (2) to obtain drum mill liners with different section panel angle combinations. Then, the drum mill liners with different section panel angle combinations are simulated based on the discrete element method. According to the characteristics of coarse particles at the feeding end and fine particles at the discharging end in step (1), more large balls are required at the feeding end and more small balls are required at the discharging end. The best combination for optimizing the axial spatial distribution of the grinding media inside the drum mill is selected. The length of the liner of the middle drum mill in step (3) is 4.8-12m; In step (3), the drum mill liner with different panel angle combinations is simulated based on the discrete element method to obtain the axial spatial distribution diagram of steel balls of different sizes. The steel ball size that is consistent with the characteristic of coarse particles at the feeding end and fine particles at the discharging end in step (1) is the optimal combination of the axial spatial distribution of the grinding media inside the drum mill.

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