Double-ellipsoid ore grinding medium and manufacturing method thereof

Abstract

The invention belongs to the technical field of ore grinding media, and particularly relates to a double-ellipsoid ore grinding medium and a manufacturing method thereof.The double-ellipsoid ore grinding medium comprises a first semi-ellipsoid and a second semi-ellipsoid, the plane of the first semi-ellipsoid is fixedly connected with the plane of the second semi-ellipsoid, and the long axis of the first semi-ellipsoid and the long axis of the second semi-ellipsoid are located on the same straight line; the length of the short axis of the first semi-ellipsoid is c, the length of the semi-major axis of the first semi-ellipsoid is a, the length of the short axis of the second semi-ellipsoid is c, the length of the semi-major axis of the second semi-ellipsoid is b, and blt; a. In the ore grinding process, along with rotation of the ball mill, the double-ellipsoid ore grinding medium is thrown off and impacts ore particles, the gravity center of the double-ellipsoid ore grinding medium deviates to the second semi-ellipsoid, the second semi-ellipsoid faces downwards during falling, the curvature of the second semi-ellipsoid is small, impact energy can be distributed more evenly in a particle bed, the smashing uniformity is improved, the over-smashing phenomenon can be effectively improved, and the service life of the double-ellipsoid ore grinding medium is prolonged. And meanwhile, the crystal penetration fracture degree caused by energy concentration is reduced, and selective dissociation of minerals is facilitated.

Description

Technical Field

[0001] The invention belongs to the technical field of grinding media, and in particular relates to a double ellipsoidal grinding medium and a manufacturing method thereof. Background Art

[0002] Ball milling is a key process that reduces particle size and dissociates minerals through the impact and grinding action of grinding media. The mechanical properties of the grinding media have a decisive influence on the grinding effect, with the contact pattern between the media and the particles directly determining the distribution of impact energy.

[0003] Research has shown that the curvature of the medium (specifically, its radius of curvature) is a key parameter influencing energy distribution: the smaller the curvature of the medium (i.e., the larger the radius of curvature), the more uniform the energy transfer to the particle bed. This characteristic offers two significant advantages: first, it produces a more uniform grinding effect, effectively suppressing over-grinding and reducing the excessive production of fine particles; second, it reduces the degree of transgranular fracture caused by energy concentration, thereby promoting the dissociation of mineral particles along grain boundaries and improving mineral dissociation efficiency. This mechanism provides an important theoretical basis for optimizing the design of grinding media parameters.

[0004] However, in practical applications, when ball milling mineral particles with a particle size of less than 6 mm, the existing steel segment or steel ball grinding media has a poor grinding effect. Therefore, a double ellipsoidal grinding medium and a manufacturing method thereof are proposed. Summary of the Invention

[0005] The object of the present invention is to provide a double ellipsoidal grinding medium and a method for manufacturing the same to solve the above problems.

[0006] To achieve the above object, the present invention provides the following solutions:

[0007] A double ellipsoidal grinding medium, comprising: a first semi-ellipsoid and a second semi-ellipsoid, wherein the plane of the first semi-ellipsoid is fixedly connected to the plane of the second semi-ellipsoid, and the major axis of the first semi-ellipsoid and the major axis of the second semi-ellipsoid fall on the same straight line;

[0008] The length of the minor axis of the first semi-ellipsoid is c, the length of the semi-major axis is a, the length of the minor axis of the second semi-ellipsoid is c, the length of the semi-major axis is b, and b <a。

[0009] The method for making a double ellipsoidal grinding medium is used to make the double ellipsoidal grinding medium, and the steps are as follows:

[0010] S1. Preparation: prepare the mold and blank, and pre-treat the blank;

[0011] S2, forming: placing the blank in a mold and punching it to obtain a rough blank;

[0012] S3, post-processing: post-processing the rough blank to obtain double ellipsoidal grinding media;

[0013] In S1, the mold includes an upper mold and a lower mold. The bottom surface of the upper mold is provided with a first semi-ellipsoidal groove with a short axis length of c and a semi-major axis length of b. The top surface of the lower mold is provided with a second semi-ellipsoidal groove with a short axis length of c and a semi-major axis length of a. The first semi-ellipsoidal groove and the second semi-ellipsoidal groove are arranged correspondingly up and down.

[0014] In the method for manufacturing a double ellipsoidal grinding medium of the present invention, in S1, the pretreatment process of the blank includes:

[0015] S11. Material selection: Select raw materials that meet the design parameters;

[0016] S12. Processing: heating the raw materials, and then dividing the raw materials into raw material segments that meet the design parameters to obtain blanks.

[0017] In the method for producing a double ellipsoidal grinding medium of the present invention, in S3, the post-processing process of the rough blank includes:

[0018] S31, milling flash: after opening the mold, use a milling cutter to mill off the flash of the rough blank without cooling;

[0019] S32, quenching: taking the rough blank out of the mold and heating it to a set temperature, and then placing the rough blank into quenching oil for oil quenching;

[0020] S33, tempering: heating the quenched rough blank to a set temperature and maintaining it for a set time to obtain a bi-ellipsoidal grinding medium.

[0021] In the method for manufacturing a double ellipsoidal grinding medium of the present invention, in S11, the material of the raw material is steel, and the shape of the raw material is cylindrical.

[0022] In the method for producing a double ellipsoidal grinding medium of the present invention, in S12, the processing includes:

[0023] The raw material is heated, clamped by a robot and subjected to axial tension, and the raw material breaks at the stress concentration point to obtain a blank. The difference between the actual length of the blank and the designed length of the blank is -5mm to 5mm.

[0024] In the method for producing a bi-ellipsoidal grinding medium of the present invention, in S12, the temperature of the raw materials after heating is 950°C to 1200°C.

[0025] In the method for manufacturing a bi-ellipsoidal grinding medium of the present invention, in S32, the quenching process is:

[0026] The rough blank is heated to 820°C to 880°C, and is placed in quenching oil. The cooling rate of the rough blank is 80°C to 100°C / s.

[0027] In the method for producing a bi-ellipsoidal grinding medium of the present invention, in S33, the quenched rough blank is heated to 150°C to 250°C and maintained at this temperature for 1.5h to 2.5h.

[0028] In the method for producing the bi-ellipsoidal grinding media of the present invention, in S2, during the forming process, the stroke speed of the press is 20 mm to 30 mm / s, and the unit pressure applied by the press is 600 MPa to 800 MPa.

[0029] Compared with the prior art, the present invention has the following advantages and technical effects:

[0030] The bi-ellipsoidal grinding medium used in the present invention is made of a first hemi-ellipsoidal body and a second hemi-ellipsoidal body with the same minor axis length and unequal semi-major axes, and its center of gravity is close to the second hemi-ellipsoidal body with the shorter semi-major axis. During the grinding process, as the ball mill rotates, the bi-ellipsoidal grinding medium is thrown down and impacts the ore particles. Because the center of gravity is biased towards the second hemi-ellipsoidal body, the hemi-ellipsoidal body faces downward when falling, and its curvature is small, which can make the impact energy more evenly distributed in the particle bed, thereby improving the uniformity of the crushing, and is more suitable for ball milling of mineral particles with a particle size of less than 6 mm. The present invention can effectively improve the over-crushing phenomenon, reduce the excessive production of fine particles, and at the same time reduce the degree of transgranular fracture caused by energy concentration, which is beneficial to the selective dissociation of minerals. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. Those skilled in the art can also derive other drawings based on these drawings without inventive work.

[0032] Figure 1 Schematic diagram of the overall structure of the double ellipsoidal grinding medium in the present invention;

[0033] Figure 2 This is a front view of the double ellipsoidal grinding medium of the present invention;

[0034] Figure 3 Schematic diagram of the structure of the mold in the present invention;

[0035] Figure 4 This is a comparison chart of different grinding media adding -43μm mineral particles in the same time;

[0036] Figure 5A comparison chart of different grinding media with -43μm mineral particles at the same specific energy consumption;

[0037] Figure 6 This is a comparison chart showing the change of mineral edge dissociation degree with mineral particle fineness under different grinding media;

[0038] Figure 7 This is a comparison chart showing how the degree of over-grinding of mineral particles changes with the fineness of mineral particles under different grinding media;

[0039] Among them, 1. The first semi-ellipsoid; 2. The second semi-ellipsoid. DETAILED DESCRIPTION

[0040] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0041] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0042] Reference Figures 1 to 2 The present invention discloses a double ellipsoidal grinding medium, comprising: a first semi-ellipsoid 1 and a second semi-ellipsoid 2, wherein the plane of the first semi-ellipsoid 1 is fixedly connected to the plane of the second semi-ellipsoid 2, and the major axis of the first semi-ellipsoid 1 and the major axis of the second semi-ellipsoid 2 fall on the same straight line;

[0043] The length of the minor axis of the first semi-ellipsoid 1 is c, the length of the semi-major axis is a, the length of the minor axis of the second semi-ellipsoid 2 is c, the length of the semi-major axis is b, and b <a。

[0044] The method for making a double ellipsoidal grinding medium is used to make a double ellipsoidal grinding medium, and the steps are as follows:

[0045] S1. Preparation: prepare the mold and blank, and pre-treat the blank;

[0046] S2, forming: placing the blank in a mold and punching it to obtain a rough blank;

[0047] S3, post-processing: post-processing the rough blank to obtain double ellipsoidal grinding media;

[0048] In S1, the mold includes an upper mold and a lower mold. The bottom surface of the upper mold is provided with a first semi-ellipsoidal groove with a short axis length of c and a semi-major axis length of b. The top surface of the lower mold is provided with a second semi-ellipsoidal groove with a short axis length of c and a semi-major axis length of a. The first semi-ellipsoidal groove and the second semi-ellipsoidal groove are arranged correspondingly up and down.

[0049] In an optional solution, in S1, the pretreatment process of the blank includes:

[0050] S11. Material selection: Select raw materials that meet the design parameters;

[0051] S12. Processing: heating the raw materials, and then dividing the raw materials into raw material segments that meet the design parameters to obtain blanks.

[0052] In an optional solution, in S3, the post-processing process of the rough blank includes:

[0053] S31, milling flash: after opening the mold, use a milling cutter to mill off the flash of the rough blank without cooling;

[0054] S32, quenching: taking the rough blank out of the mold and heating it to a set temperature, and then placing the rough blank into quenching oil for oil quenching;

[0055] S33, tempering: heating the quenched rough blank to a set temperature and maintaining it for a set time to obtain a bi-ellipsoidal grinding medium.

[0056] In an optional solution, in S11 , the material of the raw material is steel, and the shape of the raw material is cylindrical.

[0057] In an optional solution, in S12, the processing includes:

[0058] The raw material is heated, clamped by a robot and subjected to axial tension, and the raw material breaks at the stress concentration point to obtain a blank. The difference between the actual length of the blank and the designed length of the blank is -5mm to 5mm.

[0059] In an optional solution, in S12, the temperature of the raw material after heating is 950°C to 1200°C.

[0060] In an optional solution, in S32, the quenching process is:

[0061] The rough blank is heated to 820°C to 880°C, and is placed in quenching oil. The cooling rate of the rough blank is 80°C to 100°C / s.

[0062] In an optional solution, in S33, the quenched rough blank is heated to 150°C to 250°C and maintained for 1.5h to 2.5h.

[0063] In an optional solution, in S2, during forming, the stroke speed of the press is 20 mm to 30 mm / s, and the unit pressure applied by the press is 600 MPa to 800 MPa.

[0064] One specific implementation method:

[0065] Mold opening: refer to Figure 3 The mold includes an upper mold and a lower mold. The bottom surface of the upper mold is provided with a first semi-ellipsoidal groove with a short axis length of c and a semi-major axis length of b. The top surface of the lower mold is provided with a second semi-ellipsoidal groove with a short axis length of c and a semi-major axis length of a. The first semi-ellipsoidal groove and the second semi-ellipsoidal groove are arranged correspondingly up and down.

[0066] A steel column with a diameter of 40 mm is selected as the raw material. The raw material is 38CrSi alloy steel. The chromium and silicon content can improve the hardenability and high-temperature strength, making it suitable for die forging and subsequent heat treatment.

[0067] The raw materials are heated to 950°C to 1200°C, achieving a highly plastic state. A robotic gripper then applies axial tension to the material, exceeding its yield strength (80MPa to 120MPa). This forces the material to fracture ductilely at the stress concentration point, resulting in a blank. The breaking speed must match the raw material's high-temperature elongation to avoid excessive necking or uneven fracture surfaces. The blank length error is controlled within ±5mm to ensure uniform filling in subsequent die forging.

[0068] The mold is mounted on a press, the blank is placed in the lower mold, and the press is punched. The stroke speed of the press is 20mm to 30mm / s. The unit pressure applied by the press is 600MPa to 800MPa to ensure that the metal fully fills the mold cavity to obtain a rough blank. The excess metal material is squeezed into the parting surface of the upper and lower molds to form a ring-shaped flash with a thickness of about 1 to 2mm.

[0069] After forming, the mold is opened and the upper mold is removed. A carbide ball annular milling cutter with an inner diameter approximately 0.1 mm larger than the short axis length c is installed on the press to punch and mill the flash. During this process, the rough blank does not cool down. High-temperature cutting can reduce tool wear, and there is no burr on the fracture surface after the flash is removed.

[0070] Heat the rough blank to 820℃~880℃, and use No. 20 machine oil to oil quench the rough blank to avoid cracking caused by water quenching. The cooling rate is about 80℃~100℃ / s to increase the hardness and strength of the rough blank.

[0071] The rough blank is heated to 150℃~250℃ and maintained for about 2 hours to eliminate quenching stress, improve toughness and adjust hardness. The surface hardness of the resulting double ellipsoidal grinding media is ≥HRC40.

[0072] In one embodiment, the double ellipsoidal grinding media has c of 80, b of 15, and a of 70;

[0073] In one embodiment, the double ellipsoidal grinding media has c of 70, b of 25, and a of 90;

[0074] In one embodiment, the double ellipsoidal grinding media has c of 70, b of 30, and a of 80;

[0075] The following simulation verifies the ball milling efficiency of the double ellipsoidal grinding medium:

[0076] Select double ellipsoidal grinding media with c=80, b=15, a=70;

[0077] Taking the regrinding of iron ore tailings from a certain iron ore processing plant as an example, we compared the grinding efficiency and effectiveness of bi-ellipsoidal grinding media, steel balls, and steel segments. The tailings have the following properties: the -74μm content of the original ore is 85.30%, the -43μm content is 73.3%, and the 80% sieve particle size (F80) is 62μm. The target mineral is a niobium-bearing mineral.

[0078] Table 1 Test conditions of double ellipsoid grinding media, steel balls and steel segments

[0079]

[0080] Grinding speed and energy efficiency

[0081] The newly added -45μm particle size content increases with grinding time. Figure 4-5 As shown in the figure, the slope represents the grinding rate. It can be seen that the grinding speed of the dual ellipsoidal grinding medium is the fastest, followed by the steel ball, and the steel segment is the slowest. When the specific energy consumption is the same, the dual ellipsoidal grinding medium has the highest additional fine particle content, followed by the steel ball, and the steel segment has the lowest.

[0082] Product dissociation characteristics and fine particle output characteristics

[0083] The variation of target mineral edge dissociation degree with fineness is shown in Figure 6 The dissociation degree of the double ellipsoid grinding media grinding product increases most significantly with the increase of fineness. The output characteristics of the fine particle size are shown in Figure 7 It can be seen that the double ellipsoid grinding medium has the lightest degree of over-grinding.

[0084] In the description of the present invention, it should be understood that the terms "longitudinal", "transverse", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0085] The embodiments described above are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by persons skilled in the art should fall within the scope of protection defined by the claims of the present invention.

Claims

1. Double ellipsoidal grinding media, characterized in that: include: A first semi-ellipsoid (1) and a second semi-ellipsoid (2), wherein the plane of the first semi-ellipsoid (1) and the plane of the second semi-ellipsoid (2) are fixedly connected, and the major axis of the first semi-ellipsoid (1) and the major axis of the second semi-ellipsoid (2) fall on the same straight line; The length of the short axis of the first semi-ellipsoid (1) is c, and the length of the semi-major axis is a; the length of the short axis of the second semi-ellipsoid (2) is c, and the length of the semi-major axis is b, and b <a。 2. A method for producing a double ellipsoidal grinding medium, for producing the double ellipsoidal grinding medium according to claim 1, characterized in that: Here are the steps: S1. Preparation: prepare the mold and blank, and pre-treat the blank; S2, forming: placing the blank in a mold and punching it to obtain a rough blank; S3, post-processing: post-processing the rough blank to obtain double ellipsoidal grinding media; In S1, the mold includes an upper mold and a lower mold. The bottom surface of the upper mold is provided with a first semi-ellipsoidal groove with a short axis length of c and a semi-major axis length of b. The top surface of the lower mold is provided with a second semi-ellipsoidal groove with a short axis length of c and a semi-major axis length of a. The first semi-ellipsoidal groove and the second semi-ellipsoidal groove are arranged correspondingly up and down.

3. The method for producing a double ellipsoidal grinding medium according to claim 2, wherein: In S1, the pretreatment process of the blank includes: S11. Material selection: Select raw materials that meet the design parameters; S12. Processing: heating the raw materials, and then dividing the raw materials into raw material segments that meet the design parameters to obtain blanks.

4. The method for producing a double ellipsoidal grinding medium according to claim 2, wherein: In S3, the post-processing of the rough blank includes: S31, milling flash: after opening the mold, use a milling cutter to mill off the flash of the rough blank without cooling; S32, quenching: taking the rough blank out of the mold and heating it to a set temperature, and then placing the rough blank into quenching oil for oil quenching; S33, tempering: heating the quenched rough blank to a set temperature and maintaining it for a set time to obtain a bi-ellipsoidal grinding medium.

5. The method for producing a double ellipsoidal grinding medium according to claim 3, wherein: In S11, the material of the raw material is steel, and the shape of the raw material is a cylinder.

6. The method for producing a bi-ellipsoidal grinding medium according to claim 3, wherein: In S12, the processing includes: The raw material is heated, clamped by a robot and subjected to axial tension, and the raw material breaks at the stress concentration point to obtain a blank. The difference between the actual length of the blank and the designed length of the blank is -5mm to 5mm.

7. The method for producing a double ellipsoidal grinding medium according to claim 3, wherein: In S12, the temperature of the raw material after heating is 950°C to 1200°C.

8. The method for producing a double ellipsoidal grinding medium according to claim 4, wherein: In S32, the quenching process is: The rough blank is heated to 820°C to 880°C, and is placed in quenching oil. The cooling rate of the rough blank is 80°C to 100°C / s.

9. The method for producing a double ellipsoidal grinding medium according to claim 4, wherein: In S33, the quenched rough billet is heated to 150°C to 250°C and maintained for 1.5h to 2.5h.

10. The method for producing a double ellipsoidal grinding medium according to claim 2, wherein: In S2, during molding, the stroke speed of the press is 20 mm to 30 mm / s, and the unit pressure applied by the press is 600 MPa to 800 MPa.

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