A large-diameter semi-autogenous grinding + ball grinding system ball charging method

Abstract

The present application relates to a kind of big diameter semi-autogenous grinding + ball grinding system's ball charging method, including one-stage semi-autogenous grinding ball charging method and two-stage ball mill ball charging method, one-stage semi-autogenous grinding according to the structure of ore, the color and hardness of each constituent mineral determine the best calculation parameter, avoid the diameter of steel ball calculated based on the largest ore block, lead to steel ball too big, produce through crushing, make semi-autogenous grinding lose selectivity;Also avoid the irregular ore block due to stress concentration, lead to the steel ball calculated too big, make easy-to-grind useful mineral produce overgrinding;Two-stage ball mill fully considers the influence of high steel ball lifting angle in big diameter ball mill and grinding effect, calculate the ball diameter of corresponding particle size after screening classification to feed ore, and according to the ratio of larger particle size percentage, ball charging is carried out, guarantee the impact crushing effect of big ball and the grinding effect of each diameter steel ball after natural wear and tear, reduce the situation of overgrinding, so that the grinding granularity distribution is more reasonable.

Description

Technical Field

[0001] This invention belongs to the field of grinding technology, specifically relating to a method for loading balls into a large-diameter semi-autogenous grinding + ball mill system. Background Technology

[0002] In mineral processing, the complete liberation of valuable minerals through crushing and grinding is a prerequisite for mineral separation, and the grinding effect directly affects the technical and economic indicators of the mineral processing operation. Currently, ball mills are commonly used for grinding. However, ball mills of different diameters or ores of different particle sizes often require steel balls of different sizes, and as the steel balls wear down, they need to be replenished in a timely manner to ensure grinding effect and efficiency. Therefore, finding a scientific method for replenishing balls for ball mills of different diameters or ores of different particle sizes is a challenge that needs to be overcome by those skilled in the art.

[0003] Currently, the ball mill loading methods used by mineral processing enterprises mainly rely on semi-empirical formulas for fine ball mill loading of small-diameter ball mills or directly use empirical formulas for ball diameter estimation from abroad. These formulas originated in the 1980s. In the early stages of this era, my country's mineral processing industry was in its infancy, with small-scale processing plants, easily processed ores, and less stringent requirements for mineral processing indicators and energy consumption. Therefore, the ball loading methods used were relatively crude. With industrial development and the continuous expansion of mineral processing plant scale, the ball mills used have become increasingly larger, leading to the development of advanced processes such as semi-autogenous grinding combined with ball milling. This process involves both a primary semi-autogenous grinding mill and a secondary ball mill, both of which are large-diameter mills (liner diameter approximately 4-6m or larger). Furthermore, the primary semi-autogenous grinding mill in this process serves as a substitute for medium and fine crushers to perform primary crushing of large-particle ores (generally above 200mm), and the secondary ball mill further refines the ore crushed in the primary semi-autogenous grinding mill. Therefore, this process differs significantly from traditional single-unit small-diameter ball mill grinding.

[0004] To investigate the problems with calculating the replacement balls using existing empirical formulas, technicians adopted the "semi-theoretical formula for ball diameter" (proposed for the crushing and grinding process of ball mills with a diameter less than 3.2m) disclosed in CN1278775C for a precise ball mill replacement method, to calculate the replacement balls for a large-diameter semi-autogenous mill + ball mill system. Practice showed that the diameter of the steel balls in the first-stage semi-autogenous mill calculated using the "semi-theoretical formula for ball diameter" is larger, while the diameter of the steel balls in the second-stage ball mill is smaller. This results in a greater impact and less grinding effect from the steel balls in the first-stage semi-autogenous mill, leading to a larger output particle size after the primary crushing of large-particle ore. When these larger particles enter the second-stage ball mill, the smaller diameter of the steel balls results in less impact and greater grinding effect, preventing effective crushing of the large-particle ore and causing low liberation of valuable minerals. Meanwhile, small-particle ore is over-ground, resulting in an unreasonable particle size distribution after secondary fine grinding, severely impacting the technical and economic indicators of subsequent mineral sorting. Summary of the Invention

[0005] To address the aforementioned problems, this invention aims to provide a ball loading method for a large-diameter semi-autogenous grinding + ball mill system, applicable to the grinding process of semi-autogenous grinding + ball milling. This method makes the size, quantity, and proportion of the loaded balls in each stage of the process more precise and reasonable, thereby improving grinding efficiency and grinding effect, reducing energy consumption, and providing mineral particles with a reasonable particle size distribution for the sorting process.

[0006] The specific technical solution is: a ball loading method for a large-diameter semi-autogenous grinding + ball mill system, including a ball loading method for a first-stage semi-autogenous grinding mill and a ball loading method for a second-stage ball mill, wherein:

[0007] (1) A method for loading balls into a semi-autogenous grinding mill, comprising the following steps:

[0008] A. Group the ores according to their structure, the color of each constituent mineral, and their hardness. From each group of ores to be processed, identify the single mineral or near-single mineral with the largest average diameter. Finally, select the one with the highest uniaxial compressive strength σ. max It is used for calculating the diameter of the ball used for ball repair;

[0009] B. The maximum uniaxial compressive strength σ in step A max Substitute 60% to 70% of the value into the steel ball diameter calculation formula-1 to calculate the diameter of the ball used in the semi-autogenous grinding mill.

[0010] Formula-1:

[0011]

[0012] In the formula: D is the diameter of the steel ball (cm); d is the average diameter of a single mineral or near-single mineral (cm), taken as the maximum particle size passing through the 95% sieve; σ is the uniaxial compressive strength of a single mineral or near-single mineral (kg / cm²). 2m is the coefficient of the grinding effect factor; The ball mill rotational speed is % The effective density of the steel balls in the slurry, i.e., the density difference between the steel balls and the slurry, is 5.8 g / cm³ when the grinding concentration is 75%. 3 D0 is the diameter (cm) of the "impact condensation ball layer" of the steel ball layer in the mill.

[0013] The specific values ​​of the coefficient m, which is the influencing factor of grinding effect, are as follows:

[0014]

[0015] C. The initial ball loading rate of the semi-automatic ball mill is 12% to 18%, and balls are added every 24 hours.

[0016] (2) The method for loading balls into a two-stage ball mill includes the following steps:

[0017] D. Perform particle size screening on the discharge material from the semi-autogenous mill and the return sand from the second-stage ball mill. The minerals are screened into four particle sizes: 10mm~5mm, 5mm~3mm, 3mm~2mm, and -2mm. Calculate the mass percentage of each particle size.

[0018] E. Based on the maximum uniaxial compressive strength of the ore and the grinding effect influence factor coefficient m, use Formula-1 to calculate the steel ball diameters corresponding to the upper limit particle sizes of 10mm, 5mm, 3mm, and 2mm for the four particle size groups in step D.

[0019] The specific values ​​of the coefficient m, which is the influencing factor of grinding effect, are as follows:

[0020]

[0021] F. Initial ball loading procedure for the two-stage ball mill: According to the mass percentage of each particle size in step D, the steel ball diameter calculated in step E is matched accordingly for ball loading. The ball loading rate is determined according to the ball mill model. The ball loading rate for overflow ball mills is 30% to 35%, and the ball loading rate for grid ball mills is 35% to 40%.

[0022] G. Ball replenishment system for the second-stage ball mill: After the semi-autogenous grinding + ball mill system has been running stably for 48 hours, the overflow of the hydrocyclone classification is screened and analyzed. Based on the screening results, steel balls are replenished. The diameter of the steel balls is calculated with particle sizes of 10mm, 5mm, and 3mm as the boundaries. According to the principle of grinding large ore with large balls and grinding small ore with small balls, a combination of three ball diameters is selected for addition. The addition ratio is 20% to 30% for large balls, 30% to 40% for medium balls, and 20% to 30% for small balls. In principle, when there are too many coarse particles, the upper limit of large steel balls is used, and when there are too many fine particles, the lower limit of small steel balls is used. Balls are replenished once every 24 hours.

[0023] Furthermore, in step C, the ball replenishment rate of the semi-automatic ball mill is 1.2% to 3.0%.

[0024] The beneficial effects of this invention are as follows: This method closely follows the characteristics of the two stages of the semi-autogenous grinding + ball milling system to determine the ball loading method. The first stage of semi-autogenous grinding cleverly determines the optimal calculation parameters based on the ore structure, the color and hardness of each constituent mineral, avoiding the calculation of the steel ball diameter based on the largest ore block, which would result in oversized steel balls, causing through-crushing and making the semi-autogenous grinding crushing lose its selectivity. It also avoids the situation where irregularly shaped ore blocks in the mill are more easily crushed than medium and fine particles due to stress concentration, leading to over-grinding of easily grindable useful minerals. The second stage of ball milling fully considers the impact of the high lifting angle of the steel balls and the grinding effect in the large-diameter ball mill. After screening and classifying the feed, the ball diameter of the corresponding particle size is calculated, and the balls are loaded according to the percentage of the larger particle size. Small balls are no longer separately loaded for the -2mm particle size. This ensures the impact crushing effect of the large balls and also makes full use of the grinding effect after the steel balls of each diameter naturally wear down, reducing the situation of over-grinding and making the particle size distribution of the ground ore more reasonable. Precise and reasonable replenishment of steel balls at each stage can not only improve grinding efficiency and grinding effect, and increase the degree of liberation of useful minerals, but also reduce energy consumption and improve the technical and economic indicators of separation technology. Attached Figure Description

[0025] Figure 1 This is a process flow diagram of the large-diameter semi-autogenous grinding + ball milling system of the present invention. Detailed Implementation

[0026] To make the technical problems and solutions solved by the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely for explaining the present invention and are not intended to limit the present invention. Example 1

[0027] Raw material 1#: Gold-silver-containing iron oxide ore with a particle size of -250mm.

[0028] The grinding operation of the feed ore is carried out using the ball loading method of the large-diameter semi-autogenous grinding + ball mill system described in this invention. The specific steps are as follows:

[0029] (1) Ball loading of a semi-autogenous mill

[0030] A. Group the ores according to their structure, color, and hardness. Identify single or near-single minerals with a maximum average diameter of 45 mm from each group of ores to be processed. Finally, select the mineral with the highest uniaxial compressive strength σ. max =1180kg / cm 2 ;

[0031] B. The maximum uniaxial compressive strength σ in step A max (kg / cm) 2 Substitute 60% to 70% of the value into the steel ball diameter calculation formula-1 to calculate the diameter of the balls used in the semi-autogenous grinding mill.

[0032] Formula-1:

[0033]

[0034] In the formula: D is the diameter of the steel ball (cm); d is the average diameter of a single mineral or near-single mineral (cm), taken as the maximum particle size passing through the 95% sieve; σ is the uniaxial compressive strength of a single mineral or near-single mineral (kg / cm²). 2 m is the coefficient of the grinding effect factor; The ball mill rotational speed is % D0 represents the effective density of the steel balls in the slurry, i.e., the density difference between the steel balls and the slurry; D0 is the diameter (cm) of the "impact condensation ball layer" of the steel ball layer in the mill.

[0035] Specifically: d=40cm, σ max =1180kg / cm 2 m=0.02, =80%, =5.8g / cm 3 , =480cm

[0036] After calculation, D=115mm, that is, the diameter of the initial ball loading and the replenished ball loading of the semi-autogenous mill are both 115mm. The initial ball loading rate is 13%, and the replenished ball loading rate is 1.4% after 24 hours of operation.

[0037] After two months of operation, the results were compared with the operating indicators before the method was used. The results showed that: ① the proportion of ore discharge particles with a size of 0.074mm increased by 6%, while the proportion of particles with a size of -0.002mm was only 4.56%. The crushing compliance rate of large-particle ore increased by 10%, and the over-grinding of small-particle ore decreased by 7.5%; ② the unit volume productivity of the semi-autogenous mill increased by 9%; ③ ball consumption decreased by 6%.

[0038] (2) Ball loading in the second-stage ball mill

[0039] D. The discharge from the semi-autogenous mill and the return sand from the second-stage ball mill were subjected to particle size screening. The minerals were screened into four particle sizes: 10mm-5mm, 5mm-3mm, 3mm-2mm, and -2mm. Among them, the 10mm-5mm particle size accounted for 14.50%, the 5mm-3mm particle size accounted for 40.50%, the 3mm-2mm particle size accounted for 25%, and the -2mm particle size accounted for 20%.

[0040] E. Based on the maximum uniaxial compressive strength of the ore and the grinding effect influence factor coefficient m, use Formula-1 to calculate the steel ball diameters corresponding to the upper limit particle sizes of 10mm, 5mm, 3mm, and 2mm for the four particle size groups in step D.

[0041] Formula-1:

[0042] Where: σ = 1180 kg / cm 2 The value of m is 0.029 for 10mm, 0.034 for 5mm, 0.044 for 3mm, and 0.056 for 2mm. =80%, =5.8g / cm 3 , =480cm

[0043] Calculations showed that the corresponding steel ball diameters for particle sizes of 10mm, 5mm, 3mm, and 2mm were 70mm, 60mm, 50mm, and 40mm, respectively.

[0044] F. Initial ball loading system for the two-stage ball mill: The steel ball diameter calculated in step E is loaded according to the mass percentage of each particle size in step D, i.e., 70mm:60mm:50mm:40mm=15%:40%:25%:20%. In this embodiment, the overflow ball mill is used and the ball loading rate is 35%.

[0045] G. Ball replenishment system for the second-stage ball mill: After the semi-autogenous grinding + ball mill system has been running stably for 48 hours, the overflow from the hydrocyclone stage is screened and analyzed. Based on the screening results, steel balls are replenished. The diameter of the steel balls is calculated using 10mm, 5mm, and 3mm particle sizes as boundaries, using Formula-1:

[0046] Where: σ = 1180 kg / cm 2 For m, the value is 0.029 for 10mm, 0.034 for 5mm, and 0.044 for 3mm. =80%, =5.8g / cm 3 , =480cm

[0047] Calculations showed that the steel ball diameters corresponding to particle sizes of 10mm, 5mm, and 3mm were 70mm, 60mm, and 40mm, respectively.

[0048] The ball replenishment ratio is 70mm:60mm:40mm = 20%:50%:30%, and the balls are replenished once every 24 hours.

[0049] After two months of operation, the results were compared with the operating indicators before the method was used. The results showed that: ① the proportion of ore discharge particles with a size of 0.074mm increased by 4%, while the proportion of particles with a size of -0.002mm was only 3.85%. The crushing compliance rate of large-sized ore increased by 6%, and the over-grinding of small-sized ore decreased by 3%; ② the unit volume productivity of the ball mill increased by 7%; ③ ball consumption decreased by 8%. Example 2

[0050] Raw material #2: Copper-gold-silver-iron sulfide ore with a particle size of -250mm.

[0051] The grinding operation of the feed ore is carried out using the ball loading method of the large-diameter semi-autogenous grinding + ball mill system described in this invention. The specific steps are as follows:

[0052] (1) Ball loading of a semi-autogenous mill

[0053] A. Group the ores according to their structure, the color of each constituent mineral, and their hardness. From each group of ores to be processed, identify the single or near-single mineral with a maximum average diameter of 50 mm. Finally, select the mineral with the highest uniaxial compressive strength σ. max =1200 (kg / cm) 2 );

[0054] B. The maximum uniaxial compressive strength σ in step A max (kg / cm) 2 Substitute 60% to 70% of the value into the steel ball diameter calculation formula-1 to calculate the diameter of the balls used in the semi-autogenous grinding mill.

[0055] Formula-1:

[0056]

[0057] In the formula: D is the diameter of the steel ball (cm); d is the average diameter of a single mineral or near-single mineral (cm), taken as the maximum particle size passing through the 95% sieve; σ is the uniaxial compressive strength of a single mineral or near-single mineral (kg / cm²). 2 m is the coefficient of the grinding effect factor; The ball mill rotational speed is % The effective density of the steel ball in the slurry is the density difference between the steel ball and the slurry. The diameter of the "impact condensation ball layer" in the steel ball layer of the mill is cm;

[0058] Specifically: d=50cm, σ max =1200kg / cm 2 m=0.02, =80%, =5.8g / cm 3 , =480cm

[0059] After calculation, D=130mm, that is, the diameter of the initial ball loading and the replenished ball loading of the semi-autogenous mill are both 130mm. The initial ball loading rate is 15%, and the replenished ball loading rate is 2.8% after 24 hours of operation.

[0060] After two months of operation, the results were compared with the operating indicators before the method was used. The results showed that: ① the proportion of ore discharge particles with a size of 0.074mm in the semi-autogenous mill increased by 8%, while the proportion of particles with a size of -0.010mm was 7.47%. The crushing compliance rate of large-particle ore increased by 5%, and the over-grinding of small-particle ore decreased by 4%; ② the unit volume productivity of the semi-autogenous mill increased by 7%; ③ ball consumption decreased by 6%.

[0061] (2) Ball loading in the second-stage ball mill

[0062] D. The discharge from the semi-autogenous mill and the return sand from the second-stage ball mill were subjected to particle size screening. The minerals were screened into four particle sizes: 10mm-5mm, 5mm-3mm, 3mm-2mm, and -2mm. Among them, the 10mm-5mm particle size accounted for 20%, the 5mm-3mm particle size accounted for 40%, the 3mm-2mm particle size accounted for 20%, and the -2mm particle size accounted for 20%.

[0063] E. Based on the maximum uniaxial compressive strength of the ore and the grinding effect influence factor coefficient m, use Formula-1 to calculate the steel ball diameters corresponding to the upper limit particle sizes of 10mm, 5mm, 3mm, and 2mm for the four particle size groups in step D.

[0064] Formula-1:

[0065] Where: σ = 1200 kg / cm 2 (m takes values ​​of 0.029 for 10mm, 0.034 for 5mm, 0.044 for 3mm, and 0.056 for 2mm). =80%, =5.8g / cm 3 , =480cm

[0066] Calculations showed that the corresponding steel ball diameters for particle sizes of 10mm, 5mm, 3mm, and 2mm were 70mm, 60mm, 50mm, and 40mm, respectively.

[0067] F. Initial ball loading system for the two-stage ball mill: The steel ball diameter calculated in step E is loaded according to the mass percentage of each particle size in step D, i.e., 70mm:60mm:50mm:40mm=20%:40%:20%:20%. In this embodiment, an overflow ball mill is used with a ball loading rate of 33%.

[0068] G. Ball replenishment system for the second-stage ball mill: After the semi-autogenous grinding + ball mill system has been running stably for 48 hours, the overflow from the hydrocyclone stage is screened and analyzed. Based on the screening results, steel balls are replenished. The diameter of the steel balls is calculated using 10mm, 5mm, and 3mm particle sizes as boundaries, using Formula-1:

[0069] Where: σ = 1200 kg / cm 2 For m, the value is 0.029 for 10mm, 0.034 for 5mm, and 0.044 for 3mm. =80%, =5.8g / cm 3 , =480cm

[0070] Calculations showed that the steel ball diameters corresponding to particle sizes of 10mm, 5mm, and 3mm were 70mm, 60mm, and 40mm, respectively.

[0071] The ball replenishment ratio is 70mm:60mm:40mm = 30%:40%:30%, and the balls are replenished once every 24 hours.

[0072] After two months of operation, the results were compared with the operating indicators before the method was used. The results showed that: ① the proportion of ore discharge particles with a size of 0.074mm increased by 7%, while the proportion of particles with a size of -0.010mm was 12.68%. The crushing compliance rate of large-particle ore increased by 6%, and the over-grinding of small-particle ore decreased by 12%; ② the unit volume productivity of the ball mill increased by 8%; ③ ball consumption decreased by 7%. Example 3

[0073] Raw material #3: Copper-lead-zinc-gold-silver-iron sulfide ore with a particle size of -250mm.

[0074] The grinding operation of the feed ore is carried out using the ball loading method of the large-diameter semi-autogenous grinding + ball mill system described in this invention. The specific steps are as follows:

[0075] (1) Ball loading of a semi-autogenous mill

[0076] A. Group the ores according to their structure, the color of each constituent mineral, and their hardness. From each group of ores to be processed, identify the single or near-single mineral with a maximum average diameter of 50 mm. Finally, select the mineral with the highest uniaxial compressive strength σ. max =1200 (kg / cm) 2 );

[0077] B. The maximum uniaxial compressive strength σ in step A max (kg / cm) 2Substitute 60% to 70% of the value into the steel ball diameter calculation formula-1 to calculate the diameter of the balls used in the semi-autogenous grinding mill.

[0078] Formula-1:

[0079]

[0080] In the formula: D is the diameter of the steel ball (cm); d is the average diameter of a single mineral or near-single mineral (cm), taken as the maximum particle size passing through the 95% sieve; σ is the uniaxial compressive strength of a single mineral or near-single mineral (kg / cm²). 2 m is the coefficient of the grinding effect factor; ρ0 is the effective density of the steel balls in the slurry, i.e., the density difference between the steel balls and the slurry; D0 is the diameter of the "impact condensation ball layer" of the steel ball layer in the mill (cm).

[0081] Specifically: d=50cm, σ max =1200kg / cm 2 m=0.02, =80%, =5.8g / cm 3 , =480cm

[0082] After calculation, D=130mm, that is, the diameter of the initial ball loading and the replenished ball loading of the semi-autogenous mill are both 130mm. The initial ball loading rate is 15%, and the replenished balls are added after 24 hours of operation, with a replenishment rate of 2.5%.

[0083] After two months of operation, the results were compared with the operating indicators before the method was used. The results showed that: ① the proportion of ore discharge particles with a size of 0.074 mm increased by 11%, while the proportion of particles with a size of -0.010 mm was 6.43%. The crushing compliance rate of large-particle ore increased by 8%, and the over-grinding of small-particle ore decreased by 5%; ② the unit volume productivity of the semi-autogenous mill increased by 6%; ③ ball consumption decreased by 8%.

[0084] (2) Ball loading in the second-stage ball mill

[0085] D. The discharge from the semi-autogenous mill and the return sand from the second-stage ball mill were subjected to particle size screening. The minerals were screened into four particle sizes: 10mm-5mm, 5mm-3mm, 3mm-2mm, and -2mm. Among them, the 10mm-5mm particle size accounted for 20%, the 5mm-3mm particle size accounted for 40%, the 3mm-2mm particle size accounted for 20%, and the -2mm particle size accounted for 20%.

[0086] E. Based on the maximum uniaxial compressive strength of the ore and the grinding effect influence factor coefficient m, use Formula-1 to calculate the steel ball diameters corresponding to the upper limit particle sizes of 10mm, 5mm, 3mm, and 2mm for the four particle size groups in step D.

[0087] Formula-1:

[0088] Where: σ = 1200 kg / cm 2 (m takes values ​​of 0.029 for 10mm, 0.034 for 5mm, 0.044 for 3mm, and 0.056 for 2mm). =80%, =5.8g / cm 3 , =480cm

[0089] Calculations showed that the corresponding steel ball diameters for particle sizes of 10mm, 5mm, 3mm, and 2mm were 70mm, 60mm, 50mm, and 40mm, respectively.

[0090] F. Initial ball loading system for the two-stage ball mill: The steel ball diameter calculated in step E is loaded according to the mass percentage of each particle size in step D, i.e., 70mm:60mm:50mm:40mm=20%:40%:20%:20%. In this embodiment, an overflow ball mill is used with a ball loading rate of 33%.

[0091] G. Ball replenishment system for the second-stage ball mill: After the semi-autogenous grinding + ball mill system has been running stably for 48 hours, the overflow from the hydrocyclone stage is screened and analyzed. Based on the screening results, steel balls are replenished. The diameter of the steel balls is calculated using 10mm, 5mm, and 3mm particle sizes as boundaries, using Formula-1:

[0092] Where: σ = 1200 kg / cm 2 For m, the value is 0.029 for 10mm, 0.034 for 5mm, and 0.044 for 3mm. =80%, =5.8g / cm 3 , =480cm

[0093] Calculations showed that the steel ball diameters corresponding to particle sizes of 10mm, 5mm, and 3mm were 70mm, 60mm, and 40mm, respectively.

[0094] The ball replenishment ratio is 70mm:60mm:40mm = 30%:40%:30%, and the balls are replenished once every 24 hours.

[0095] After two months of operation, the results were compared with the operating indicators before the method was used. The results showed that: ① the proportion of ore discharge particles with a size of 0.074 mm increased by 5%, while the proportion of particles with a size of -0.010 mm was 9.79%. The crushing compliance rate of large-sized ore increased by 6%, and the over-grinding of small-sized ore decreased by 15%; ② the unit volume productivity of the ball mill increased by 8%; ③ ball consumption decreased by 7%.

[0096] In summary, this method of adding balls to a large-diameter semi-autogenous mill + ball mill system can improve the ore's compliance rate after grinding, increase the degree of liberation of valuable minerals, and reduce the overflow fineness of ore particles. This has practical significance for improving the technical and economic indicators of the separation process. Simultaneously, the high grinding efficiency effectively reduces equipment energy consumption, achieving cost reduction and efficiency improvement. This method is particularly suitable for the development of polymetallic ore bodies composed of multiple valuable minerals and has significant potential for widespread application and demonstration.

[0097] The present invention has been described in detail above through specific and preferred embodiments. However, those skilled in the art should understand that the present invention is not limited to the embodiments described above. Any modifications, equivalent substitutions, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for loading balls into a large-diameter semi-autogenous grinding + ball mill system, comprising a ball loading method for a first-stage semi-autogenous grinding mill and a ball loading method for a second-stage ball mill, wherein: (1) A method for loading balls into a semi-autogenous grinding mill, comprising the following steps: A. According to the structure of the ore, the color and hardness of each component mineral, group the ore, find the largest average diameter of single mineral or near single mineral from each group of ore to be processed, and finally select the largest single axial compressive strength σ max , for the calculation of the ball diameter B. Calculate the diameter of the balls used to fill the semi-autogenous grinding mill according to formula -1; Formula-1: ； In the formula: D is the diameter of the steel ball (cm); d is the average diameter of a single mineral or near-single mineral (cm), taken as the maximum particle size passing through the 95% sieve; σ is the uniaxial compressive strength of a single mineral or near-single mineral (kg / cm²). 2 The value of σ is 60% to 70% of the maximum uniaxial compressive strength σmax in step A; m is the coefficient of the grinding effect influence factor. ρ0 is the effective density of the steel balls in the slurry, i.e., the density difference between the steel balls and the slurry; D0 is the diameter (cm) of the "impact condensation ball layer" of the steel ball layer in the mill. The specific values ​​of the coefficient m, which is the influencing factor of grinding effect, are as follows: ； C. The initial ball loading rate of the semi-automatic ball mill is 12% to 18%, and balls are added every 24 hours. (2) The method for loading balls into a two-stage ball mill includes the following steps: D. Perform particle size screening on the discharge material from the semi-autogenous mill and the return sand from the second-stage ball mill. The minerals are screened into four particle sizes: 10mm~5mm, 5mm~3mm, 3mm~2mm, and -2mm. Calculate the mass percentage of each particle size. E. Use Formula-1 to calculate the steel ball diameters corresponding to the upper limit particle sizes of 10mm, 5mm, 3mm, and 2mm for the four particle size groups in step D. In Formula-1, the value of σ is the maximum uniaxial compressive strength σmax in step A. The specific values ​​of the coefficient m, which is the influencing factor of grinding effect, are as follows: ； F. Initial ball loading procedure for the two-stage ball mill: According to the mass percentage of each particle size in step D, the steel ball diameter calculated in step E is matched accordingly for ball loading. The ball loading rate is determined according to the ball mill model. The ball loading rate for overflow ball mills is 30% to 35%, and the ball loading rate for grid ball mills is 35% to 40%. G. Ball mill replenishment system for the second stage: After the semi-autogenous grinding + ball mill system has been running stably for 48 hours, the overflow of the hydrocyclone classification is screened and analyzed. Based on the screening results, steel balls are replenished. The diameter of the steel balls is calculated with 10mm, 5mm and 3mm as the boundaries. According to the principle of grinding large ore with large balls and grinding small ore with small balls, a combination of three ball diameters is selected for addition. The addition ratio is 20% to 30% for large balls, 30% to 40% for medium balls and 20% to 30% for small balls. Balls are replenished once every 24 hours.

2. The ball loading method for a large-diameter semi-autogenous grinding + ball milling system according to claim 1, characterized in that, In step C, the ball replenishment rate of the semi-automatic ball mill is 1.2% to 3.0%.

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