A method for determining a new type of highly efficient and energy-saving polyhedral grinding medium

Abstract

The present invention relates to a method for determining a new type of highly efficient and energy-saving polyhedral grinding medium, and belongs to the field of grinding in ore dressing. Firstly, the shape of the new type of polyhedral grinding medium is determined based on the Solidworks three-dimensional modeling software. The polyhedral grinding medium takes the four vertices of a regular tetrahedron as the sphere center, and the tetrahedron formed by the intersection of four spheres with the edge length of the regular tetrahedron as the radius and the spherical surface is composed of 4 spherical surfaces, 4 vertices and 6 edges, and the angle between each spherical surface is 120°; then the spherical radius of the polyhedral grinding medium is determined according to the modified Duan's semi-theoretical formula; finally, the particle size composition of the product entering the mill is screened to determine the polyhedral grinding medium ratio. The present invention can improve the processing capacity of the mill, reduce the grinding energy consumption and grinding medium consumption, and improve the quality of the grinding product; it overcomes the defects of low grinding efficiency and poor quality of grinding products in traditional spherical grinding media; the grinding medium is determined by this method, and it is universally applicable to mines of different types of ores and different sizes.

Description

Technical Field

[0001] The invention relates to a method for determining a novel high-efficiency and energy-saving polyhedral grinding medium, and in particular provides a novel grinding medium suitable for a grinding mill and determines its shape and size, and belongs to the field of grinding in ore dressing. Background Art

[0002] Ore is an important strategic resource. my country's demand for ore ranks among the highest in the world. The development of all industries in my country is inseparable from ore. Each ore has its own unique properties. If the ore is not fully dissociated in the grinding stage, it will be extremely unfavorable for the subsequent separation process of the ore. If the ore is not fully dissociated or it is over-crushed, it will cause a waste of ore resources.

[0003] Grinding is the process of reducing the particle size of ore to powder by means of the impact and grinding of grinding media (steel balls, steel rods, steel segments) and the ore itself in mechanical equipment. The purpose is to achieve the maximum separation of the useful minerals and gangue minerals that make up the ore, so as to provide materials with particle sizes that meet the requirements of the next ore dressing process.

[0004] Grinding is the core unit for achieving efficient and selective separation of minerals, and grinding media is the most important factor affecting mill energy consumption, steel consumption and particle size characteristics of grinding products. Current theoretical, experimental, numerical simulation research and industrial applications of mineral processing plants are mainly based on spheres, rods and short columns, and there is a lack of design and research on new polyhedral grinding media.

[0005] In the mineral processing industry, the shape, size, material and filling rate of the grinding media directly affect the grinding efficiency, metal recovery rate and metal material consumption. Therefore, the research on the shape, size and material of the grinding media has always been the focus of research in this field.

[0006] At present, the most common grinding media used in mills are steel balls, steel rods, etc. Steel balls are typical point-contact grinding media. The crushing force at the contact point is too large and the crushing force accuracy is poor, so the spherical grinding media has poor selective dissociation and serious over-crushing. As a grinding medium, steel rods have the functions of selectively crushing coarse particles and selectively protecting fine particles, so that the product particle size is uniform, but its disadvantages are also obvious. It cannot be added at any time during the production process. The medium must be added when the machine is shut down, which is labor-intensive. Moreover, due to its own wear, it is easy to have disordered rods and twisted rods, which affects normal production and causes great damage to production equipment.

[0007] For hard and brittle minerals, line contact always produces better selective grinding than point contact grinding media. It can be inferred that for hard and brittle minerals, the larger the contact area with the ore to be ground, the better the selective grinding effect should be.

[0008] At present, spherical media are the most widely used, but spherical media present point contact during crushing, and the force at the contact point is often too large, which easily causes penetrating crushing, so the selective dissociation is poor, and the grinding is not fine and over-crushing is serious. Compared with spherical media, rod-shaped and short columnar media present line contact during crushing. Although it can reduce over-crushing, the crushing force is not as strong as that of spheres, and the same particle size of feed is often not ground fine. Summary of the invention

[0009] The purpose of the present invention is to provide a method for determining a new type of polyhedral grinding medium with high efficiency and energy saving. The polyhedral grinding medium solves the problem of mismatch between crushing force and energy of grinding media at the current stage, and can greatly improve the grinding efficiency, thereby achieving the purpose of reducing costs and increasing efficiency.

[0010] The technical solution of the present invention is a method for determining a novel high-efficiency and energy-saving polyhedral grinding medium, and the specific steps are as follows:

[0011] (1) Determination of the shape of polyhedral grinding media

[0012] The polyhedral grinding medium has four vertices of a regular tetrahedron as the sphere center, and the tetrahedron formed by the intersection of four spheres with the edge length of the regular tetrahedron as the radius and the spherical surface consists of 4 spherical surfaces, 4 vertices and 6 edges, and the angle between each spherical surface is 120°.

[0013] (2) Determination of steel ball diameter

[0014] Take m tons of representative ore sample from the crossflow on the grinding belt, conduct subdivision and screening, obtain the information of particle size distribution in the ore sample, and determine the corresponding steel ball diameter D according to the segment ball diameter semi-theoretical formula for each particle size in the ore. 球 ;

[0015]

[0016] Where: D 球 The precise ball diameter required for the feed particle size d under specific grinding conditions;

[0017] K c is the comprehensive experience correction coefficient;

[0018] Ψ is the mill rotation speed;

[0019] σ 压 is the uniaxial compressive strength of rock and mineral;

[0020] ρ e is the effective density of the steel ball in the slurry;

[0021] D0 is the diameter of the middle condensation layer of the steel ball in the mill;

[0022] d is the particle size of 95% of the mill feed sieve;

[0023] (3) Determination of the radius of the spherical surface of the polyhedral grinding medium

[0024] Under the condition of the same mass, the spherical radius of the polyhedron grinding medium is:

[0025] D 新 =2.15D 球 ;

[0026] (4) Determination of polyhedral grinding media ratio

[0027] The proportion of the corresponding polyhedral grinding media is determined by the proportion of different particle sizes in the feed ore.

[0028] Furthermore, the specific implementation steps for determining the shape of the polyhedral grinding medium are: first, draw a regular tetrahedron in Solidworks; then make four spheres with the four vertices of the regular tetrahedron as the sphere center and the edge length of the regular tetrahedron as the radius; finally, obtain a tetrahedron formed by the intersection of the four spheres and the spherical surface through Boolean operation.

[0029] Furthermore, the weight m of the representative ore sample intercepted on the belt entering the mill is determined by the maximum particle size of the ore sample entering the mill, m = Kd 2 , K is a coefficient related to the properties of the ore, and its value ranges from 0.02 to 0.8.

[0030] Furthermore, the polyhedral grinding medium material is one of low / high chromium alloy, cast iron, and ceramic.

[0031] Furthermore, the manufacturing process of the polyhedron grinding medium is one of casting, forging and rolling.

[0032] The beneficial effects of the present invention are:

[0033] 1. The present invention is a new type of polyhedral grinding medium, the surface of which is a spherical surface with a large radius. On the basis of traditional grinding media (steel balls), the contact area with the ore to be ground is increased, which can effectively improve the crushing efficiency of the ore to be ground and reduce the over-crushing of the ore to be ground, which is more efficient and energy-saving.

[0034] 2. Under the same volume conditions, the arrangement of the novel polyhedral grinding media of the present invention is different from that of the spherical media, and its stacking density is improved. This more compact arrangement reduces the volume of the mill occupied by the grinding media and can greatly improve the processing capacity of the mill.

[0035] 3. The novel polyhedral grinding medium of the present invention has good rotation performance in the mill and can move smoothly, thereby enabling the grinding medium and the ore to be ground to maintain good fluidity during the operation of the mill.

[0036] 4. The method for determining the polyhedral grinding medium of the present invention is simple and practical, and does not require a large amount of tedious calculations, but can obtain better grinding efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a flow chart of the method for determining the novel high-efficiency and energy-saving polyhedral grinding medium of the present invention;

[0038] Figure 2 It is a schematic diagram of the three-dimensional structure of the polyhedral grinding medium of the present invention;

[0039] Figure 3 is a front view of the polyhedral grinding medium of the present invention;

[0040] Figure 4 is a left side view of the polyhedral grinding medium of the present invention;

[0041] Figure 5 is a top view of the polyhedral grinding medium of the present invention;

[0042] Figure 6 This is an analysis diagram of the particle size characteristics of the grinding product under the two grinding media conditions in Example 1;

[0043] Figure 7 This is an analysis diagram of the particle size characteristics of the grinding product under two grinding media conditions in Example 2;

[0044] Figure 8 This is an analysis diagram of the particle size characteristics of the grinding product under the two grinding media conditions in Example 3. DETAILED DESCRIPTION

[0045] A method for determining a novel polyhedral grinding medium with high efficiency and energy saving is described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0046] like Figure 1 As shown, a method for determining a new type of high-efficiency and energy-saving polyhedral grinding medium is provided, and the specific steps are as follows:

[0047] (1) Determination of the shape of polyhedral grinding media

[0048] The polyhedral grinding medium is a tetrahedron formed by the intersection of four spheres with the four vertices of the regular tetrahedron as the sphere center and the edge length of the regular tetrahedron as the radius and the spherical surface. Figure 2-5As shown, it consists of 4 spherical surfaces, 4 vertices and 6 edges, and the angle between each spherical surface is 120°. The shape of the polyhedral grinding medium is determined based on the Solidworks 3D modeling software. First, a regular tetrahedron is drawn in Solidworks; then four spheres are made with the four vertices of the regular tetrahedron as the sphere center and the edge length of the regular tetrahedron as the radius; finally, the tetrahedron formed by the intersection of the four spheres and the spherical surface is obtained through Boolean operation. The grinding area of ​​this polyhedral grinding medium is increased by about 10% compared with the steel ball, the contact radius is increased by 29%, and the bulk density is increased by 10%. Therefore, the mill processing capacity is increased, the degree of over-crushing is reduced, and high efficiency and energy saving are achieved.

[0049] (2) Determination of steel ball diameter

[0050] Take m tons of representative ore sample from the crossflow on the grinding belt, m is determined by the maximum particle size of the ore sample entering the grinding mill, and conduct reduction screening to obtain information on the particle size distribution in the ore sample. Then, determine the corresponding steel ball diameter D according to the segmental ball diameter semi-theoretical formula for each particle size in the ore. 球 ;

[0051]

[0052] Where: D 球 —The exact ball diameter required for the feed particle size d under specific grinding conditions, cm;

[0053] K c —Comprehensive experience correction coefficient;

[0054] Ψ—mill speed;

[0055] σ 压 —Uniaxial compressive strength of rock and mineral, kg / cm 2 ;

[0056] ρ e —Effective density of steel ball in slurry, g / cm 3 ;

[0057] D0—diameter of the middle condensation layer of the steel ball in the mill, cm;

[0058] d—95% sieve size of mill feed, cm;

[0059] (3) Determination of the radius of the spherical surface of the polyhedral grinding medium

[0060] Under the condition of the same mass, the spherical radius of the polyhedron grinding medium is:

[0061] D 新 =2.15D 球 ;

[0062] (4) Determination of polyhedral grinding media ratio

[0063] The proportion of the corresponding polyhedral grinding media is determined by the proportion of different particle sizes in the feed ore.

[0064] Specifically, the weight m of the representative ore sample intercepted on the belt entering the mill is determined by the maximum particle size of the ore sample entering the mill. Generally, in order to ensure the representativeness of the sample, the minimum mass m required is Kd 2 , K is a coefficient related to the properties of the ore, and its value ranges from 0.02 to 0.8.

[0065] Specifically, the polyhedral grinding medium material is one of low / high chromium alloy, cast iron, and ceramic.

[0066] Specifically, the manufacturing process of the polyhedron grinding medium is one of casting, forging and rolling.

[0067] Example 1

[0068] In this embodiment, K c =1.12; rotation rate 75%; by δ t =3.62 and grinding concentration R = 75%, considering the influence of extremely uneven mechanical properties, according to the average compressive strength and correction coefficient, the ball mill D can be obtained. 球 =97.1mm, and 100mm is taken as the final maximum spherical diameter. According to the principle of equal mass replacement, it can be determined that the maximum spherical diameter of the new polyhedral medium sphere is 215mm.

[0069] According to the maximum abrasive particle size of 50mm, corresponding to P 95 12mm, 2 tons of representative ore samples were scraped from the mill belt, and the whole mill feed was divided into the following six particle sizes: +8mm, -8+5mm, -5+2mm, -2+0.90mm, -0.90+0.45mm and -0.45mm. The grinding -0.074mm content is required to be 30%, which is equivalent to the grinding particle size of 0.45mm. -0.45mm is the grade that does not need to be ground. After deducting -0.45mm, the yield of the grade to be ground can be obtained, the required ball diameter of each group can be determined, and finally the initial ball ratio of the ball mill can be determined, as shown in Table 1.

[0070] Table 1 Ball mill initial loading medium ratio calculation table (Example 1)

[0071]

[0072] The test data analysis results are shown in Figure 6As can be seen from the figure, after using the new polyhedral medium, the yield of +0.45mm over-coarse particle size was reduced by 2.95%, the yield of -0.074+0.038mm intermediate easy-to-select grade was increased by 3.94%, the yield of -0.038mm over-crushed was reduced by 1.15%, and the yield of -0.074mm qualified particle size was increased by 5.79%, which greatly improved the quality of grinding products.

[0073] Example 2

[0074] In this embodiment, K c =1.12, rotation rate 75%; by δ t =3.25 and grinding concentration R = 75%, considering the extremely uneven mechanical properties and the influence of high toughness, according to the average compressive strength and correction coefficient, the ball mill D can be obtained. 球 =68.7mm, and 70mm is taken as the final maximum spherical diameter. According to the principle of equal mass replacement, it can be determined that the maximum spherical diameter of the new polyhedral medium sphere is 150.5mm.

[0075] According to the maximum abrasive particle size of 45mm, corresponding to P 95 12mm, 2 tons of representative ore samples were scraped from the mill belt, and the whole mill feed was divided into the following five particle sizes: +8mm, -8+2mm, -2+0.45mm, -0.45+0.20mm, -0.20mm. The yield of the -0.074mm grade is required to reach 60-65%, which is equivalent to the grinding particle size of 0.20mm. -0.20mm is the grade that does not need to be ground. After deducting -0.20mm, the yield of the grade to be ground can be obtained, and the required ball diameter of each group can be determined. Finally, the initial ball ratio of the ball mill is determined, as shown in Table 2.

[0076] Table 2 Ball mill initial loading medium ratio calculation table (Example 2)

[0077]

[0078] The test data analysis results are shown in Figure 7 As can be seen from the figure, after using the new polyhedral medium, the yield of +0.20mm over-coarse particle size was reduced by 0.65%, the yield of -0.074+0.018mm intermediate easy-to-select grade was increased by 4.25%, the yield of -0.010mm over-crushed was reduced by 8.5%, and the yield of -0.074mm qualified particle size was increased by 4.21%, improving the quality of grinding products.

[0079] Example 3

[0080] In this embodiment, K c =1.00; rotation rate 74%; by δ t=3.21 and grinding concentration R = 75%, considering the influence of extremely uneven mechanical properties, according to the average compressive strength and correction coefficient, the ball mill D can be obtained. k =79.7mm, and 80mm is taken as the final maximum spherical diameter. According to the principle of equal mass replacement, it can be determined that the maximum spherical diameter of the new polyhedral medium sphere is 172mm.

[0081] According to the maximum grinding particle size of 60mm, corresponding to P 95 15mm, 3 tons of representative ore samples were scraped from the mill belt, and the whole mill feed was divided into the following six particle sizes: +12mm, -12+8mm, -8+5mm, -5+2mm, -2+0.2mm and -0.2mm. The grinding -0.074mm content is required to reach 56% to 60%, which is equivalent to the grinding particle size of 0.20mm. -0.20mm is the grade that does not need to be ground. After deducting -0.20mm, the yield of the grade to be ground can be obtained, the required ball diameter of each group can be determined, and finally the initial ball ratio of the ball mill can be determined, as shown in Table 3.

[0082] Table 3 Ball mill initial loading medium ratio calculation table (Example 3)

[0083]

[0084] The test data analysis results are shown in Figure 8 As can be seen from the figure, after using the new polyhedral medium, the yield of +0.20mm over-coarse particle size was reduced by 7.04%, the yield of -0.074+0.032mm intermediate easy-to-select grade was increased by 4.79%, the yield of -0.032mm over-crushed was reduced by 3.19%, and the yield of -0.074mm qualified particle size was increased by 7.98%, improving the quality of grinding products.

[0085] The high-efficiency and energy-saving new type of polyhedral medium of the present invention has a grinding area increased by about 10% compared with steel balls, a contact radius increased by 29%, and a bulk density increased by 10%. Therefore, the mill processing capacity is increased and the degree of over-crushing is reduced.

[0086] The specific implementation modes of the present invention are described in detail above with reference to examples. However, the present invention is not limited to the above implementation modes. Various changes can be made within the knowledge scope of ordinary technicians in this field without departing from the purpose of the present invention.

Claims

1. A method for determining a novel high-efficiency and energy-saving polyhedral grinding medium, characterized in that: The specific steps of the method are as follows: (1) Determination of the shape of polyhedral grinding media The polyhedral grinding medium has four vertices of a regular tetrahedron as the sphere center, and the tetrahedron formed by the intersection of four spheres with the edge length of the regular tetrahedron as the radius and the spherical surface consists of 4 spherical surfaces, 4 vertices and 6 edges, and the angle between each spherical surface is 120°; (2) Determination of steel ball diameter Take m tons of representative ore sample from the crossflow on the grinding belt, conduct subdivision and screening, obtain the information of particle size distribution in the ore sample, and determine the corresponding steel ball diameter D according to the segment ball diameter semi-theoretical formula for each particle size in the ore. 球 ; Where: D 球 The precise ball diameter required for the feed particle size d under specific grinding conditions; K c is the comprehensive experience correction coefficient; Ψ is the mill rotation speed; σ 压 is the uniaxial compressive strength of rock and mineral; ρ e is the effective density of the steel ball in the slurry; D0 is the diameter of the middle condensation layer of the steel ball in the mill; d is the 95% sieve size of the mill feed; (3) Determination of the radius of the spherical surface of the polyhedral grinding medium Under the condition of the same mass, the spherical radius of the polyhedron grinding medium is: D 新 =2.15D 球 ; (4) Determination of polyhedral grinding media ratio The proportion of the corresponding polyhedral grinding media is determined by the proportion of different particle sizes in the feed ore.

2. A method for determining a novel high-efficiency and energy-saving polyhedral grinding medium according to claim 1, characterized in that: The specific implementation steps for determining the shape of the polyhedral grinding medium are: first, draw a regular tetrahedron in Solidworks; then make four spheres with the four vertices of the regular tetrahedron as the sphere center and the edge length of the regular tetrahedron as the radius; finally, obtain a tetrahedron formed by the intersection of the four spheres and the spherical surface through Boolean operation.

3. A method for determining a novel high-efficiency and energy-saving polyhedral grinding medium according to claim 1, characterized in that: The weight m of the representative ore sample intercepted from the crossflow on the grinding belt is determined by the maximum particle size d of the ore sample entering the grinding mill, m = Kd 2 , K is a coefficient related to the properties of the ore, and its value ranges from 0.02 to 0.

8.

4. A method for determining a novel high-efficiency and energy-saving polyhedral grinding medium according to claim 1, characterized in that: The polyhedral grinding medium material is one of low / high chromium alloy, cast iron and ceramic.

5. A method for determining a novel high-efficiency and energy-saving polyhedral grinding medium according to claim 1, characterized in that: The manufacturing process of the polyhedron grinding medium is one of casting, forging and rolling.

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