Method for grinding ore in a horizontal ball mill with a mixture of steel segments and ceramic balls

Abstract

The application relates to a method for mixing and grinding of steel segments and ceramic balls in an easy-over-ground mineral horizontal ball mill, and belongs to the technical field of grinding in mineral processing. The steel segment gradation is determined as follows: first, the diameter of the steel ball is determined according to the mechanical properties of the ore through a formula, the diameter of the steel ball calculated is converted into the specification of the steel segment according to the same quality principle, and the gradation of the steel segment is obtained through the grade yield of the to-be-ground particles; the gradation of the steel segment is converted according to the equal size conversion principle, the adding proportion of each specification of ceramic ball is consistent with the adding proportion of the steel segment of the same size, and the proportion of the ceramic ball is obtained; and the mass ratio of the mixed medium is determined according to the mechanical properties and the particle size composition of the raw ore and the test. The steel segment and the ceramic ball are mixed as the grinding medium, the gradation of the steel segment and the gradation of the ceramic ball are obtained through calculation, and the feasibility and the accuracy of the gradation of the mixed medium are verified through the test, so that a feasible method for improving the particle size composition of the grinding product and reducing over-grinding is provided.

Description

Technical Field

[0001] This invention relates to a method for grinding steel sections and ceramic balls together in a horizontal ball mill for easily ground minerals, belonging to the field of grinding technology in mineral processing. Background Technology

[0002] Grinding is a crucial operation in mineral processing plants, responsible for providing qualified raw materials for subsequent processes. The quality of the grinding product directly impacts beneficiation indicators. As my country's mineral resources gradually deplete and become more complex and less refined, existing processes place higher demands on grinding, requiring both sufficient liberation of minerals and prevention of over-grinding, while simultaneously minimizing grinding costs.

[0003] Commonly used grinding media include steel balls, steel segments, and ceramic balls. Currently, ball mills primarily use steel balls as the grinding media, especially in the first stage of grinding. Steel balls have good rotational performance, point contact crushing, and high crushing force, making them effective for grinding difficult-to-grind ores. However, steel balls have poor selective cleavage, resulting in strong penetrating crushing when used for easily over-grindable minerals, leading to severe over-grinding. In industrial applications, when using steel balls to grind easily over-grindable minerals, the filling rate is often low, generally not exceeding 25%, which limits the efficiency of the ball mill; at the same time, the particle size distribution of the ground product is also not ideal.

[0004] Steel segments are mainly used in the second stage of grinding. Industrial trials have proven that in the fine grinding stage, steel segments are more effective than steel balls. At the same throughput, the amount of over-grinding and over-grinding particles in the grinding product is significantly reduced, the yield of qualified particles is significantly increased, and the product particle size is more uniform. Therefore, steel segments are more suitable for fine grinding. Ceramic balls are mainly used in vertical mills as ultrafine grinding media. Ultrafine grinding is primarily for grinding, and ceramic balls of the same mass have a larger surface area and volume than steel balls. A larger surface area is more conducive to grinding, while a larger volume results in a higher filling rate. Therefore, higher requirements are placed on the filling rate of the mill. Thus, ceramic balls are mainly used in vertical mills, where the filling rate can exceed 60%. Vertical mills are for compression crushing, and ceramic balls are wear-resistant, corrosion-resistant, and have high hardness. Therefore, using ceramic balls in vertical mills can reduce over-grinding and lower energy consumption.

[0005] The density of a steel ball is approximately 7800 kg / m³. 3 It is a ceramic ball with a capacity of 3800 kg / m³ 3The surface area of ​​ceramic balls is 1.8 times that of steel balls, while the surface area of ​​ceramic balls of the same mass is approximately 1.6 times that of steel balls. The filling rate of a conventional horizontal ball mill generally does not exceed 45%. Therefore, when using this method to replace steel balls in a conventional horizontal ball mill, the steel ball filling rate should not exceed 25%, which is exactly the same as the critical filling rate for grinding easily over-grindable minerals with steel balls. Currently, there are no domestic cases of using a mixture of steel segments and ceramic balls as grinding media in conventional horizontal ball mills. For fine grinding of easily over-grindable minerals, the grinding action should be enhanced to increase the surface area of ​​the grinding media, while a slight crushing force should be applied to prevent coarse particles from becoming unbreakable. Therefore, this method is applicable to grinding easily over-grindable minerals in conventional horizontal ball mills. Summary of the Invention

[0006] To address the problems and shortcomings of the existing technology, this invention provides a method for grinding easily over-grindable minerals using a horizontal ball mill by mixing steel segments and ceramic balls. This invention uses a mixture of steel segments and ceramic balls as the grinding media. The gradation of the steel segments and ceramic balls is calculated, and the feasibility and accuracy of the mixed media gradation are verified through experiments. This provides a feasible method for improving the particle size distribution of grinding products and reducing over-grinding.

[0007] A method for grinding easily ground minerals by mixing steel sections with ceramic balls in a horizontal ball mill, comprising the following steps: Step 1: Determine the gradation of steel segments (1) First, determine the diameter of the steel ball according to the mechanical properties of the ore using formula (1), and then measure the diameter of the steel ball. Value, the introduced function and Substitute into the formula for calculating the diameter of a steel ball:

[0008] in: —Ore extraction percentage at each mining site, % —Protodextrin hardness coefficient; —Secant modulus of elasticity; —Secant Poisson's ratio; —Break function; —Breakage function; —The arithmetic mean of the Protodyakonov hardness coefficients of all mining sites; —The arithmetic mean of the secant elastic modulus of all mining points; —The arithmetic mean of the secant Poisson's ratios for all mining sites; —Number of mining sites; (2) Based on the steel ball diameter calculated in step (1), the steel segment specifications are converted according to the principle of equal mass, and the steel segment gradation is obtained through the yield of the grinding particle size. Step 2: Determine the ceramic ball ratio The steel segment gradation obtained from step (2) of Step 1 is calculated according to the principle of equal size conversion, and the addition ratio of ceramic balls of each specification is consistent with the addition ratio of steel segments of the same size to obtain the ceramic ball ratio; Step 3: Determine the mass ratio of the mixed media The mass ratio of the mixing medium is determined based on the mechanical properties and particle size distribution of the raw ore and experimental results.

[0009] After determining the mass ratio of the mixed medium in Step 3 above, conduct tests with the same time and fineness as with a single steel segment and a single ceramic ball, respectively, and verify the accuracy of the mixed gradation based on the results.

[0010] The working principle of this invention is as follows: For fine grinding of easily over-grindable minerals, the grinding action should be primarily focused on abrasion. However, steel balls of the same size have a greater impact force than steel segments and ceramic balls. Therefore, when steel balls are used as the fine grinding medium, over-grinding is more severe. In ball mills, this phenomenon becomes more pronounced with increasing filling rate. The density of steel balls is 1.8 times that of ceramic balls, and the surface area of ​​ceramic balls of the same mass is approximately 1.6 times that of steel balls. The filling rate of easily over-grindable minerals using steel balls is generally no more than 25%, and the filling rate of conventional horizontal ball mills is generally no more than 45%. The ratio of their filling rates is also 1.8. Therefore, when using ceramic balls in conventional horizontal ball mills for fine grinding of easily over-grindable minerals, increasing the ceramic ball filling rate can increase the grinding surface area, compensating for the disadvantage of lower ceramic ball density. Steel segments can effectively reduce over-grinding of the product and have a certain crushing force. Different types of ores have different grindability; by adjusting the gradation of steel segments, ceramic balls, and their mass ratio, different easily over-grindable ores can be adapted.

[0011] The beneficial effects of this invention are as follows: This invention uses a mixture of steel segments and ceramic balls as the grinding medium in a horizontal ball mill, overcoming the defects of low throughput and poor product particle size characteristics when grinding easily over-grindable minerals in a conventional horizontal ball mill, where the steel ball filling rate cannot exceed 25%. After optimization by this method, the media filling rate of easily over-grindable minerals in a conventional horizontal ball mill can reach up to 45%. At this point, the mixed medium of steel segments and ceramic balls has both a certain crushing force and ensures a large surface area. Because the ceramic balls have a low density, they are less likely to cause over-grinding, which can effectively improve the product particle size characteristics. Attached Figure Description

[0012] Figure 1 This is a process flow diagram of the present invention. Detailed Implementation

[0013] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. Example 1

[0014] like Figure 1As shown, taking the Yunnan Hualian zinc-indium polymetallic mine as an example, the method of grinding easily ground minerals by mixing steel sections and ceramic balls in a horizontal ball mill includes the following steps: Step 1: Determine the gradation of steel segments (1) First, determine the diameter of the steel ball according to the mechanical properties of the ore using formula (1), and then measure the diameter of the steel ball. Value, the introduced function and Substitute into the formula for calculating the diameter of a steel ball:

[0015] in: —Ore extraction percentage at each mining site, % —Protodextrin hardness coefficient; —Secant modulus of elasticity; —Secant Poisson's ratio; —Break function; —Breakage function; —The arithmetic mean of the Protodyakonov hardness coefficients of all mining sites; —The arithmetic mean of the secant elastic modulus of all mining points; —The arithmetic mean of the secant Poisson's ratios for all mining sites; —Number of mining sites; (2) Based on the steel ball diameter calculated in step (1), the steel segment specifications are converted according to the principle of equal mass, and the steel segment gradation is obtained through the yield of the grinding particle size. The calculated steel segment gradation is 45×50:30×40:30×35:25×30=30:20:30:20.

[0016] Step 2: Determine the ceramic ball ratio The steel segment gradation obtained from step (2) of Step 1 is calculated according to the principle of equal size conversion (45×50 steel segment is equivalent to 50mm ceramic ball, and so on), and the addition ratio of ceramic balls of each specification is consistent with the addition ratio of steel segments of the same size. The ceramic ball ratio is 50:40:35:30=30:20:30:20.

[0017] Step 3: Determine the mass ratio of the mixed media Based on the mechanical properties of the ore and grinding tests, the mass ratio of the mixing media was determined. The steel segment ratio (45×50:30×40:30×35:25×30=30:20:30:20) and the ceramic ball ratio (50:40:35:30=30:20:30:20) were mixed in a certain proportion. If the ore has high hardness or low fine particle size, the mass ratio of steel segments can be increased as appropriate. The specific mass ratio of steel segments to ceramic balls needs to be verified by grinding tests. For example, the Hualian zinc-indium ore sample in this test is brittle and has a high content of fine particles, so the proportion of ceramic balls can be appropriately increased. Grinding tests with steel segment:ceramic ball ratio = 1:2 and steel segment:ceramic ball ratio = 2:1 were conducted for the same grinding time. The grinding results are shown in Table 1.

[0018]

[0019] As shown in Table 1, when the grinding tests were conducted for the same grinding time, (1) the fine grinding capacity of ratio 1 was the strongest; (2) the yield of -0.074mm in ratio 1 was 1.64 percentage points higher than that of ratio 2, the yield of the coarse particle +0.15mm decreased by 0.10 percentage points, and the yields of the intermediate selectable particle -0.10+0.019mm and the intermediate easily selectable particle -0.074+0.038mm increased by 1.24 percentage points and 0.96 percentage points, respectively.

[0020] Analysis of the particle size distribution of the grinding test products showed that ratio 1 had a stronger fine grinding capacity than the steel segment ratio and the ceramic ball ratio. The yield of the coarse particle size (+0.15mm) decreased, while the yields of the intermediate selectable particle size (-0.10+0.019mm) and the intermediate easily selectable particle size (-0.074+0.038mm) both increased. Therefore, the mass ratio of the mixed media can be determined as steel segment ratio: ceramic ball ratio = 1:2 (ratio 1).

[0021] The mixed media gradation (ratio 1) obtained in Step 3 above was compared with that of a single steel segment (steel segment gradation of 45×50:30×40:30×35:25×30=30:20:30:20) and a single ceramic ball (ceramic ball gradation of 50:40:35:30=30:20:30:20) under the same grinding media quality and grinding time. The grinding results are shown in Table 2.

[0022]

[0023] Table 2 shows that when the three grinding media were tested under the same mass and grinding time: (1) the mixed media ratio had the strongest fine grinding ability; (2) the yield of -0.074mm of the mixed media ratio was 12.54 percentage points higher than that of the steel segment ratio, the yield of the overly coarse +0.15mm particle size decreased by 1.51 percentage points, and the yields of the intermediate selectable particle size -0.10+0.019mm and the intermediate easily selectable particle size -0.074+0.038mm increased by 4.87 percentage points and 7.45 percentage points, respectively, but The yield of the over-grinding particle size -0.038mm increased by 5.09 percentage points; (3) The yield of the mixed medium ratio of -0.074mm increased by 3.45 percentage points compared with the ceramic ball ratio, the yield of the coarse particle size +0.15mm decreased by 0.19 percentage points, the yield of the intermediate selectable particle size -0.10+0.019mm and the intermediate easy selectable particle size -0.074+0.038mm increased by 4.46 percentage points and 4.41 percentage points respectively, but the yield of the over-grinding particle size -0.038mm increased by 0.95 percentage points.

[0024] Therefore, the fine grinding capability of the mixed media ratio is stronger than that of the steel segment ratio and the ceramic ball ratio. The yield of the coarse particle size (+0.15mm) is reduced, while the yields of the intermediate selectable particle size (-0.10+0.019mm) and the intermediate easily selectable particle size (-0.074+0.038mm) are both improved.

[0025]

[0026] As shown in Table 3, when the three grinding media were tested at the same grinding fineness: (1) the yield of +0.15mm of the mixed media ratio was 1.32 percentage points lower than that of the steel segment ratio, the yield of the intermediate selectable particle size -0.10+0.019mm and the yield of the intermediate easily selectable particle size -0.074+0.038mm were increased by 7.13 percentage points and 8.12 percentage points respectively, and the yield of the over-grinding particle size -0.038mm was decreased by 8.25 percentage points; (2) the yield of +0.15mm of the mixed media ratio was 0.24 percentage points lower than that of the ceramic ball ratio, the yield of the intermediate selectable particle size -0.10+0.019mm and the yield of the intermediate easily selectable particle size -0.074+0.038mm were increased by 1.46 percentage points and 5.80 percentage points respectively, and the yield of the over-grinding particle size -0.038mm was decreased by 6.10 percentage points.

[0027] The grinding products of the mixed media exhibit an oval-shaped distribution. The yields of the over-coarse particle size (+0.15 mm) and the over-grinding particle size (-0.038 mm) are both low, while the yields of the intermediate selectable particle size (-0.10 +0.019 mm) and the intermediate easily selectable particle size (-0.074 +0.038 mm) are both high. Among the three grinding media, the product has the best particle size characteristics and the least over-grinding.

[0028] Based on the above steps, the grinding media gradation of Yunnan Hualian Zinc-Indium Polymetallic Mine is determined to be steel segment gradation: ceramic ball gradation = 1:2, where the steel segment ratio is 45×50:30×40:30×35:25×30 = 30:20:30:20; and the ceramic ball ratio is 50:40:35:30 = 30:20:30:20.

[0029] The specific embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A method for grinding steel sections and ceramic balls together in a horizontal ball mill for easily ground minerals, characterized in that... Includes the following steps: Step 1: Determine the gradation of steel segments (1) First, determine the diameter of the steel ball according to the mechanical properties of the ore using formula (1), and then measure the diameter of the steel ball. , , , , , Value, the introduced function and Substitute into the formula for calculating the diameter of a steel ball: （1）； ； (2) Based on the steel ball diameter calculated in step (1), the steel segment specifications are converted according to the principle of equal mass, and the steel segment gradation is obtained through the yield of the grinding particle size. Step 2: Determine the ceramic ball ratio The steel segment gradation obtained from step (2) of Step 1 is calculated according to the principle of equal size conversion, and the addition ratio of ceramic balls of each specification is consistent with the addition ratio of steel segments of the same size to obtain the ceramic ball ratio; Step 3: Determine the mass ratio of the mixed media The mass ratio of the mixing medium is determined based on the mechanical properties and particle size distribution of the raw ore and experimental results. The grinding products of the mixed media formulation exhibit an oval-shaped distribution.

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