A Design Method for the Liner Structure to Prevent the Clamping of Steel Balls and Ore Particles in a Semi-Autogenous Mill

Abstract

The present invention provides a design method for the lining plate structure to prevent the clamping of steel balls and ore particles in a semi-autogenous mill. The design method refers to: by establishing a mechanical model of the clamping phenomenon, analyzing the change trend of the critical clamping force with the change of the lining plate structure parameters and the parameters of the semi-autogenous mill, obtaining a relationship curve graph of the critical clamping force changing with the angle of the lining plate lifting strip and the rotational speed, and thus determining the optimal structural characteristics of the lining plate. The present invention reduces the possibility of particle clamping by adjusting the angle of the lining plate lifting strip and the rotational speed of the semi-autogenous mill, prevents the steel balls and ore from falling directly onto the lining plate after jumping over the free-falling position, improves the service life of the lining plate, improves the grinding efficiency, and reduces the grinding energy consumption.

Description

Technical Field

[0001] The present invention relates to the technical field of semi-autogenous mills, and particularly relates to a design method for the lining plate structure of a semi-autogenous mill to prevent the clamping of steel balls and ore particles. Background Art

[0002] The lining plate of a semi-autogenous mill is used to protect the cylinder body, preventing it from being directly impacted and rubbed by the grinding media steel balls and ore particles. The lining plates are arranged along the circumferential direction of the cylinder body and there are multiple groups in the axial direction, as Figure 2 shown. Different structural forms of lining plates are used to adjust the movement states of the grinding media steel balls and materials in the grinding body, so as to enhance the grinding effect on the ore materials. In the figure: 1 - lifting surface, 2 - bolt boss, 3 - lifting lug rib, 4 - non-lifting surface, 5 - bottom plate.

[0003] Common lining plate structural shapes include trapezoidal lining plates (as Figure 3 shown), L-shaped lining plates (as Figure 4 , 5 shown), and the installation forms of the lining plates include high-low-high installation (as Figure 3 , 5 shown) and back-to-back (as Figure 4 shown) two installation methods. The lining plates of different structures and different installation forms inside the cylinder body form countless different forms of grooves, including local grooves formed by lifting bars, bosses, reinforcing ribs, and lifting lug rib plates. The steel balls and ore particles are distributed in the grooves. The lifting bars of the lining plates are used to lift the steel balls and ore particles to a certain height, generating a free fall of a parabolic motion, and the ore is broken by the impact work generated by the falling of the steel balls and ore.

[0004] During the operation of the semi-autogenous mill, the lining plate has a large loss, and there is a phenomenon of direct impact of steel balls and ore on the lining plate periodically or an empty impact sound. Due to the collision between particles, the steel balls and ore gathered in the grooves are clamped, resulting in the steel balls and ore being taken to a higher throwing angle before they can break away from the lifting bars, thus increasing the probability of the steel balls and ore hitting the lining plate, which will seriously affect the service life of the lining plate. If the clamping force is too large, the steel balls and ore are clamped between the lifting bars and no longer break away, which will affect the working efficiency of the semi-autogenous mill, form ineffective energy consumption, and reduce the energy efficiency of the semi-autogenous mill. Summary of the Invention

[0005] To solve the above problems, the present invention aims to propose a design method for the lining plate structure of a semi-autogenous mill to prevent the clamping of steel balls and ore particles. By establishing a mechanical model of the clamping phenomenon, analyzing the change trend of the critical clamping force with the change of the lining plate structure parameters and the parameters of the semi-autogenous mill, a relationship curve graph of the critical clamping force changing with the angle of the lining plate lifting bar and the rotation speed is obtained; by adjusting the angle of the lining plate lifting bar and the rotation speed of the semi-autogenous mill, the possibility of particle clamping is reduced.

[0006] To achieve the above object, the technical solution of the present invention is implemented as follows:

[0007] A design method for the liner structure of a semi-autogenous mill to prevent the clamping of steel balls and ore particles. The design method refers to: by establishing a mechanical model of the clamping phenomenon, analyzing the change trend of the critical clamping force with the change of the liner structure parameters and the parameters of the semi-autogenous mill, obtaining a relationship curve graph of the critical clamping force changing with the angle of the liner lifting strip and the rotation speed, and thus determining the optimal structural characteristics of the liner.

[0008] Furthermore, the design method includes the following steps:

[0009] S1: Represent the "groove" formed by the wedging of two kinds of particles, namely steel balls and ore, in the liner structure as a "clamping" model, and thus establish a mechanical model of the clamping phenomenon of steel balls and ore particles.

[0010] S2: According to the mechanical model of the clamping phenomenon of steel balls and ore particles, derive a mathematical model of the critical clamping force, and import it into the MATLAB simulation software to establish a simulation model for calculating the critical clamping force.

[0011] S3: According to the simulation model for calculating the critical clamping force, conduct a simulation calculation of the influence of the change of the liner structure parameters and the operating parameters of the semi-autogenous mill on the critical clamping force, obtain the critical clamping force when the throwing angle is 90 degrees at a certain rotation speed, and determine the surface angle structure parameters of the liner lifting surface and the non-lifting surface.

[0012] Furthermore, the groove includes the "groove" formed by the corresponding surfaces of the lifting strip, the reinforcing rib strip, the convex platform and the lifting lug rib plate.

[0013] Furthermore, the optimal structural characteristics of the liner are correspondingly related to the rotation speed of the semi-autogenous mill.

[0014] Furthermore, the design method is specifically: establish a mechanical model of the clamping pairing of steel balls and ore particles. The possible clamping pairing particle sizes of steel balls and ore particles are d 1i and d 2i respectively. Among them, the ore particle model is a spherical aggregate, and d 2i is the equivalent diameter. There are several pairings of steel balls and ore particles, and the relative positions of the steel balls and ore particles are considered to be interchanged, that is: the steel ball is on top and the ore is at the bottom; the steel ball is at the bottom and the ore is on top.

[0015] Conduct a mechanical analysis of the clamping phenomenon of steel balls and ore particles. Let the clamping force be N, the static friction coefficients between the steel balls and ore and the lifting strip be μ1 and μ2 respectively, the radius of the distribution circle of the possible clamping positions of the steel balls and ore particles be R, the angle of the lifting surface of the groove be β1, the angle of the non-lifting surface be β2, and the rotational speed of the cylinder be ω. Then:

[0016] The angles θ1 and θ2 are respectively:

[0017] θ1 = 90° - β1 - α; θ2 = 90° - α;

[0018] The interaction force between the ore and the steel balls and the supporting force of the lifting bars on the steel balls are:

[0019] N = G2·sinθ2 + N2·cosβ2 + f2·sinβ2

[0020] N1 = N cosβ1 + G1·sinθ1 + F1·sinβ1;

[0021] Centrifugal force of the steel balls:

[0022] F1 = G1·cosθ1 + N1·sinβ1 - f1·cosβ1 = m1·ω 2 ·R;

[0023] Centrifugal force of the ore:

[0024] F2 = G2·cosθ2 + N2·sinβ2 - f2·cosβ2 = m2·ω 2 ·R

[0025] Maximum static friction force between the steel balls, ore and the lifting bars:

[0026] f 1max = N1·μ1; f 2max = N2·μ2;

[0027] By integrating the above equations, the expressions of f1 and f2 can be obtained:

[0028]

[0029]

[0030] The obtained f1 and f2 are respectively compared with f1max and f2max. When f1 > f1max or f2 > f2max, that is, f 1max - f1 < 0, then:

[0031]

[0032] Or f 2max - f2 < 0, we get:

[0033]

[0034] In the above expression, the throwing angle α represents the angle at which the medium is thrown out from the lining plate. N is the interaction force between the steel balls and the ore. The minimum clamping force N at which it does not slip at any α angle is the critical clamping force. The maximum critical clamping force refers to the clamping force at which the particles do not slip when the throwing angle is 90 degrees. When the critical clamping force does not reach a certain value, the steel balls and the ore will not be clamped and will be thrown out.

[0035] Beneficial effects: By establishing a mechanical model of the clamping phenomenon, this invention analyzes the change trend of the critical clamping force with the change of the lining plate structure parameters and the semi-autogenous mill parameters, and obtains a relationship curve graph of the critical clamping force changing with the angle of the lining plate lifting strip and the rotation speed; by adjusting the angle of the lining plate lifting strip and the rotation speed of the semi-autogenous mill, the possibility of particle clamping is reduced, preventing the steel balls and the ore from directly hitting the lining plate after jumping over the free-falling position and falling, improving the service life of the lining plate, improving the grinding efficiency, and reducing the grinding energy consumption. Brief Description of the Drawings

[0036] The accompanying drawings forming a part of this invention are used to provide a further understanding of this invention. The schematic embodiments of this invention and their descriptions are used to explain this invention and do not constitute an improper limitation of this invention. In the drawings:

[0037] Figure 1 is a flowchart of the lining plate structure design method for preventing the clamping of steel balls and ore particles in the semi-autogenous mill described in the embodiment of this invention;

[0038] Figure 2 is a schematic diagram of the lining plate installation structure in the background technology of this invention;

[0039] Figure 3 is the T-shaped lining plate in the background technology of this invention;

[0040] Figure 4 is the L-shaped lining plate in the background technology of this invention;

[0041] Figure 5 is the high-low-high installation lining plate in the background technology of this invention;

[0042] Figure 6 is the mechanical model of the clamping of steel balls and ore particles described in the embodiment of this invention;

[0043] Figure 7 is the curve graph of the change of the critical clamping force with the angle of the lining plate lifting strip (steel balls on top) described in the embodiment of this invention;

[0044] Figure 8 is the curve graph of the change of the critical clamping force with the angle of the lining plate lifting strip (steel balls at the bottom) described in the embodiment of this invention;

[0045] Figure 9 is the curve graph of the relationship between the critical clamping force and the rotation speed described in the embodiment of this invention. Detailed implementation manners

[0046] It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments may be combined with each other.

[0047] The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with the embodiments.

[0048] Embodiment 1

[0049] See Figures 1-9 : A design method for the lining plate structure to prevent the clamping of steel balls and ore particles in a semi-autogenous mill. The design method refers to: by establishing a mechanical model of the clamping phenomenon, analyzing the change trend of the critical clamping force with the change of the lining plate structure parameters and the parameters of the semi-autogenous mill, obtaining a relationship curve graph of the critical clamping force changing with the angle of the lining plate lifting strip and the rotation speed, and thereby determining the optimal structural characteristics of the lining plate.

[0050] In this embodiment, based on the relationship curve graph of the critical clamping force changing with the angle of the lining plate lifting strip and the rotation speed, the angle of the lining plate lifting strip and the rotation speed of the semi-autogenous mill are adjusted to reduce the possibility of particle clamping, prevent the steel balls and ore from falling directly onto the lining plate after jumping over the free-falling position, improve the service life of the lining plate, improve the grinding efficiency, and reduce the grinding energy consumption.

[0051] In a specific example, the design method includes the following steps:

[0052] S1: Using the "groove" formed by the wedging of two kinds of particles, namely steel balls and ore, in the lining plate structure to represent the "clamping" model, and thus establishing a mechanical model of the steel ball and ore particle clamping phenomenon;

[0053] S2: According to the mechanical model of the steel ball and ore particle clamping phenomenon, deriving a mathematical model of the critical clamping force and importing it into the MATLAB simulation software to establish a simulation model for calculating the critical clamping force;

[0054] S3: According to the simulation model for calculating the critical clamping force, performing a simulation calculation on the influence of the change of the lining plate structure parameters and the operating parameters of the semi-autogenous mill on the critical clamping force, obtaining the critical clamping force when the throwing angle is 90 degrees at a certain rotation speed, and determining the surface angle structure parameters of the lining plate lifting surface and the non-lifting surface.

[0055] In a specific example, the groove includes the "groove" formed by the corresponding surfaces of the lifting strip, the reinforcing rib strip, the boss and the lifting lug rib plate.

[0056] It should be noted that for the "groove" formed by the corresponding surfaces of the lifting strip, the reinforcing rib strip, the boss and the lifting lug rib plate in this embodiment, the angles of the surfaces of each groove are designed by the above step method.

[0057] In a specific example, the optimal structural characteristics of the lining plate are correspondingly related to the rotational speed of the semi-autogenous mill.

[0058] It should be noted that the design of the lining plate structure parameters is carried out after the rotational speed is determined, that is, each rotational speed of the semi-autogenous mill in this embodiment corresponds to an optimal structural characteristic of the lining plate. When the rotational speed is too high, the free-falling positions of the steel balls and ore particles move upward, and the dropping points are too high, which may also cause the phenomenon of the steel balls hitting the lining plate empty.

[0059] In a specific example, the specific design method is as follows: Establish a mechanical model of the clamping and pairing of steel balls and ore particles as Figure 6 shown. The possible paired particle sizes of the steel balls and ore particles are d 1i and d 2i respectively. Among them, the ore particle model is a spherical aggregate, and d2i is the equivalent diameter; there are several pairs of steel balls and ore particles, and the relative positions of the steel balls and ore particles are considered to be interchanged, that is: the steel ball is on top and the ore is at the bottom; the steel ball is at the bottom and the ore is on top;

[0060] Perform a mechanical analysis of the clamping phenomenon of the steel balls and ore particles. Let the clamping force be N, the static friction coefficients between the steel balls and ore and the lifting bars be μ1 and μ2 respectively, the radius of the circular distribution of the possible clamping positions of the steel balls and ore particles be R, the angle of the lifting surface of the groove be β1, the angle of the non-lifting surface be β2, and the rotational speed of the cylinder be ω. Then:

[0061] The angles θ1 and θ2 are respectively:

[0062] θ1 = 90° - β1 - α; θ2 = 90° - α;

[0063] The interaction force between the ore and the steel ball and the supporting force of the lifting bar on the steel ball are:

[0064] N = G2·sinθ2 + N2·cosβ2 + f2·sinβ2:

[0065] N1 = N cosβ1 + G1·sinθ1 + F1·sinβ1;

[0066] The centrifugal force of the steel ball:

[0067] F1 = G1·cosθ1 + N1·sinβ1 - f1·cosβ1 = m1·ω 2 ·R;

[0068] The centrifugal force of the ore:

[0069] F2 = G2·cosθ2 + N2·sinβ2 - f2·cosβ2 = m2·ω 2 ·R

[0070] The maximum static friction force between the steel ball, ore and the lifting bar:

[0071] f 1max = N1·μ1; f 2max = N2·μ2;

[0072] Combining the above equations, the expressions of f1 and f2 can be obtained:

[0073]

[0074]

[0075] The obtained f1 and f2 are compared with f1max and f2max respectively. When f1 > f1max or f2 > f2max, that is, f 1max -f1 < 0, then:

[0076]

[0077] or f 2max -f2 < 0, we get:

[0078]

[0079] In the above expressions, the throwing angle α represents the angle at which the medium is thrown from the lining plate. N is the interaction force between the steel ball and the ore. The minimum clamping force N that does not slip at any α angle is the critical clamping force. The maximum critical clamping force refers to the clamping force when the throwing angle is 90 degrees and the particles do not slip. When the critical clamping force does not reach a certain value, the steel ball and the ore will not be clamped and will be thrown out.

[0080] See Figures 6-9 , in the specific verification, it is assumed that the clamping pairs of the steel ball and the ore are: steel ball d 11 and ore d 21 , steel ball d 12 and ore d 22 , steel ball d 13 and ore d 23 , steel ball d 14 and ore d 24 , steel ball d 15 and ore d 25 , steel ball d 16 and ore d 26 ; In addition, there are 6 pairing cases where the positions of the steel ball and the ore are interchanged.

[0081] Establish a mechanical model of the clamping phenomenon, analyze the change trend of the critical clamping force with the change of the lining plate structure parameters and the semi-autogenous mill parameters. Use MATLAB software to simulate and analyze the critical clamping force at a throwing angle of 90° for different lifting surface angles and non-lifting surface angles. Finally, obtain the relationship curve of the critical clamping force changing with the lining plate lifting bar angle at a certain rotational speed, asFigure 7 and 8 as shown

[0082] It can be seen from Figure 7 and Figure 8 that the critical clamping force increases with the increase of the lifting surface angle of the liner, indicating that the greater the lifting surface angle of the liner, the smaller the possibility of clamping. When the lifting surface angle of the lifting bar of the liner ≥ β 11 , the possibility of clamping hardly exists

[0083] When the lifting surface angle of the lifting bar is β 11 , adjust the rotational speed of the semi-autogenous mill to obtain the relationship curve of the critical clamping force changing with the rotational speed, as shown in Figure 9 as shown. It can be seen that the critical clamping force decreases with the increase of the rotational speed. Therefore, by increasing the rotational speed, the critical clamping force can be reduced. However, if the rotational speed is too high, the free-falling positions of the steel balls and ore particles move up, and the dropping point is too high, which may also cause the phenomenon of the liner being hit in vain. Therefore, the design of the liner structure parameters is carried out after the rotational speed is determined

[0084] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention

Claims

1. A design method for the lining plate structure to prevent the clamping of steel balls and ore particles in a semi-autogenous mill, characterized in that, The described design method refers to: by establishing a mechanical model of the clamping phenomenon, analyzing the change trends of the critical clamping force with the changes in the structure parameters of the liner and the parameters of the semi-autogenous mill, obtaining a relationship curve graph of the critical clamping force varying with the angle of the liner lifting bars and the rotational speed, and thereby determining the optimal structural characteristics of the liner; The described design method includes the following steps: S1: Represent the "clamping" model with two types of particles, i.e., steel balls and ore, wedged in the "grooves" formed by the liner structure, and thus establish a mechanical model of the clamping phenomenon of steel balls and ore particles; S2: According to the mechanical model of the clamping phenomenon of steel balls and ore particles, derive the mathematical model of the critical clamping force, and import it into the MATLAB simulation software to establish a simulation model for calculating the critical clamping force; S3: According to the simulation model for calculating the critical clamping force, conduct a simulation calculation of the influence of the changes in the liner structure parameters and the operating parameters of the semi-autogenous mill on the critical clamping force, obtain the critical clamping force when the throw angle is 90 degrees at a certain rotational speed, and determine the surface angle structure parameters of the liner lifting surface and the non-lifting surface.

2. The design method of the liner structure for preventing clamping of steel balls and ore particles in a semi-autogenous mill according to claim 1, characterized in that The described groove includes the "groove" formed by the corresponding surfaces of the lifting bars, reinforcing rib bars, bosses, and lifting lug rib plates.

3. The design method of the liner structure for preventing clamping of steel balls and ore particles in a semi-autogenous mill according to claim 1, characterized in that The optimal structural characteristics of the liner are correspondingly related to the rotational speed of the semi-autogenous mill.

4. The design method of the liner structure for preventing steel balls and ore particles from being clamped in the semi-autogenous mill according to claim 1, characterized in that, The specific design method is as follows: establish a mechanical model for the clamping and pairing of steel balls and ore particles. The possible paired particle sizes for clamping by the steel balls and ore particles are d 1i and d 2i respectively. Among them, the ore particle model is a spherical aggregate, and d 2i is the equivalent diameter. There are several pairings of steel balls and ore particles, and the relative positions of the steel balls and ore particles are considered to be interchangeable, that is: the steel ball is on top and the ore is at the bottom; the steel ball is at the bottom and the ore is on top; Conduct a mechanical analysis of the clamping phenomenon of steel balls and ore particles. Let the clamping force be N, and the static friction coefficients between the steel balls and ore and the lifting bars be , the radius of the distribution circle of the possible clamping positions of the steel balls and ore particles be R, the lifting surface angle of the groove be , the non-lifting surface angle be , the rotational speed of the cylinder be , then: Angle and are respectively: ； ； The interaction force between the ore and the steel balls and the supporting force of the lifting bars on the steel balls are: ； ； Centrifugal force of the steel balls: ； Centrifugal force of the ore: Maximum static friction force between the steel balls, ore, and the lifting bars: ； ； By integrating the above equations, the expressions of f1 and f2 can be obtained: Compare the obtained f1 and f2 with f1max and f2max respectively. When f1 > f1max or f2 > f2max, i.e., , then: or , we get: ； In the above expression, the throwing angle represents the angle at which the medium is thrown from the liner. N is the interaction force between the steel ball and the ore. The minimum clamping force at which it does not slip at any angle N is the critical clamping force. The maximum critical clamping force refers to the clamping force at which the particles do not slip when the throwing angle is 90 degrees. When the critical clamping force does not reach a certain value, the steel ball and the ore will not be clamped and will be thrown out.

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