Method for determining size and quantity of steel balls to be added by measuring ball mill feed size and current

Abstract

The application discloses a method for determining the size and quantity of added steel balls by measuring the ball mill feed size and current, comprising the following steps: S1, the ball mill feed is divided into 4-5 different size fractions and the mass of each fraction is accumulated, and different size steel balls are allocated to different size fractions; S2, the mass of the corresponding size fraction that needs to be accumulated is calculated according to the consumption of the grinding balls; S3, when the ball mill is running normally, the internal current is monitored in real time, and the current of the ball mill before and after the addition of the added balls is recorded; S4, the actual current I is compared with I1 and I2 during the operation of the ball mill; and S5, the step S4 is repeated. According to the application, the content of each fraction in the ball mill feed size is measured in real time, the filling rate of the steel balls in the ball mill is controlled in a proper range through the change of the current of the ball mill, the steel balls in the ball mill are in a balanced state, the grinding efficiency of the ball mill is improved, and the product size composition of the grinding is stabilized.

Description

Technical Field

[0001] This invention relates to the field of automatic control technology for grinding, specifically a method for determining the size and quantity of supplementary steel balls by measuring the particle size of the feed ore and the current of the ball mill. Background Technology

[0002] In a mineral processing plant, the overflow from grinding and classification goes directly into the subsequent beneficiation process. Its quality directly affects the indicators of the beneficiation process. Unliberated coarse particles in the overflow are not conducive to the recovery of valuable elements. Even if they are successfully recovered, they will reduce the grade of the concentrate. On the other hand, excessively liberated fine particles not only cause excessive consumption of electricity and steel, but also have an adverse effect on subsequent flotation and dewatering operations. At the same time, the working efficiency of the ball mill actually determines the throughput of the mineral processing plant.

[0003] In existing technologies, the size and quality of steel balls inside ball mills are affected by many factors, among which the size of the feed particle size, the content of each particle size, and the mechanical properties of the ore are more important. After the designers determine the steel ball replenishment plan, the size and quantity of steel balls added to the ball mill in subsequent production are fixed. The decision to add additional steel balls is made based on the ball mill's bulging condition and the particle size distribution of the ground product, which seriously affects the ball mill's working efficiency. Therefore, a more comprehensive steel ball replenishment system is needed to improve the ball mill's working efficiency. Summary of the Invention

[0004] The purpose of this invention is to provide a method for determining the size and quantity of supplementary steel balls by measuring the feed particle size and current of a ball mill. This addresses the issue raised in the background section where the size and quality of steel balls in a ball mill are influenced by many factors, among which the feed particle size, the content of each particle size, and the mechanical properties of the ore are particularly important. After the designers determine the supplementary steel ball scheme, the size and quantity of steel balls added to the ball mill in subsequent production are fixed. The need for additional steel balls is then determined based on the ball mill's expansion and the particle size distribution of the ground product, which severely impacts the ball mill's operating efficiency. Therefore, a more comprehensive steel ball supplementation system is needed to improve the ball mill's efficiency.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a method for determining the size and quantity of supplementary steel balls by measuring the feed particle size and current of a ball mill, comprising the following steps:

[0006] S1. The ball mill feed is divided into 4-5 different particle sizes and the mass of each particle size is accumulated. Different sizes of steel balls are assigned to different particle sizes.

[0007] S2. Calculate the cumulative particle size mass required to add one steel ball of each size based on the grinding ball consumption.

[0008] S3. During normal operation of the ball mill, monitor the internal current in real time and record the ball mill current before and after adding supplementary balls. The ball mill current before adding supplementary balls is recorded as follows: The ball mill current was recorded after the addition of balls. To ensure accuracy, multiple records were taken and the average value was calculated. and ;

[0009] S4. Actual current during ball mill operation and and In comparison, when ≤ ≤ When the cumulative mass of different particle sizes in the ore in step S1 is compared with the corresponding particle size mass calculated by adding one steel ball of a different size in step S2, if the mass is equal, add one steel ball of the corresponding size, then reset the cumulative mass of this particle size in the ore to zero and start accumulating again. ≤ At one time, a whole class's worth of steel balls were added at once. ≥ Stop adding balls when necessary, and monitor the ball mill's operating current in real time after adding balls all at once or stopping ball adding.

[0010] S5. Repeat step S4.

[0011] Preferably, in step S1, the ball mill feed is screened into different particle sizes using a high-frequency vibrating screen. The screen aperture sizes of the high-frequency vibrating screen include 15mm, 10mm, 8mm, 5mm, and 2mm, and the ball mill feed is divided into +15mm, +10mm, +8mm, +5mm, +2mm, and -2mm particle sizes. The number of screen layers and the screen aperture size are selected according to the particle size composition of the ball mill feed, and the yield of each particle size is controlled between 20% and 50%.

[0012] Preferably, in step S1, 90mm and 100mm steel balls are allocated to the +15mm particle size range, 80mm and 90mm steel balls to the +10mm particle size range, 70mm and 80mm steel balls to the +8mm particle size range, 60mm and 70mm steel balls to the +5mm particle size range, 50mm and 60mm steel balls to the +2mm particle size range, and 40mm and 50mm steel balls to the -2mm particle size range. The size of the steel balls allocated for each particle size range should be based on the Protodyakonov hardness coefficient of the ore. The upper limit of the Protodyakonov hardness coefficient of medium-hardness ore is 8. If the average Protodyakonov hardness coefficient of the ore is greater than 8, a larger steel ball is used; otherwise, a smaller steel ball is used.

[0013] Preferably, in step S2, the weights of steel balls of different sizes are obtained by weighing, and the corresponding particle size mass required to add one steel ball is the ratio of the weight of the steel ball of that size to the grinding ball consumption.

[0014] Preferably, in step S3, , and , All are within the rated operating current of the ball mill. and The result is a weighted average of three or more measurements, and the measured result is sent to the automatic ball-adding machine.

[0015] Preferably, in step S4, the mass of different particle sizes in the feed ore in step S1 is accumulated using an electronic belt scale. The electronic belt scale is connected to an automatic ball feeder. After the accumulated mass of the electronic belt scale reaches the corresponding particle size mass, the accumulated mass is reset to zero. The automatic ball feeder adds a steel ball of the corresponding particle size. The automatic ball feeder analyzes the data input from the electronic belt scale and the ball mill to control the number and particle size of the added balls.

[0016] Preferably, in step S4, the steel balls added in a shift are of the same mass for each size, and after calculating the number of steel balls of each size, they are added using an automatic ball-adding machine.

[0017] Compared with the prior art, the beneficial effects of the present invention are:

[0018] This invention determines the quality of added steel balls of different sizes by measuring the content of each particle size in the ball mill feed in real time. This replenishes the ball mill's grinding consumption. The ball mill's steel ball filling rate is controlled within an appropriate range by varying the ball mill's current. This is a precise, fast, and effective method for judging the size and quality of added steel balls. This invention keeps the steel balls inside the ball mill in a balanced state, thereby improving the ball mill's grinding efficiency, stabilizing the particle size composition of the ground product, and solving the problem of adding the size and quality of supplementary balls during the ball mill's production process. Detailed Implementation

[0019] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0020] The method for determining the size and quantity of supplementary steel balls by measuring the feed particle size and current of the ball mill includes the following steps:

[0021] Step 1: Separate the ball mill feed ore into 4-5 different particle size grades and accumulate the mass of each grade. Different sized steel balls are assigned to different particle size grades. The ball mill feed ore is screened using a high-frequency vibrating screen with screen aperture sizes including 15mm, 10mm, 8mm, 5mm, and 2mm. The ball mill feed ore is then divided into +15mm, +10mm, +8mm, +5mm, +2mm, and -2mm particle size grades. The number of screen layers and screen aperture size are selected based on the particle size composition of the ball mill feed ore. The yield of each particle size grade is controlled between 20% and 50%. The +15mm particle size grade is allocated... 90mm and 100mm steel balls; +10mm particle size distribution: 80mm and 90mm steel balls; +8mm particle size distribution: 70mm and 80mm steel balls; +5mm particle size distribution: 60mm and 70mm steel balls; +2mm particle size distribution: 50mm and 60mm steel balls; -2mm particle size distribution: 40mm and 50mm steel balls. The size of the steel balls for each particle size distribution should be based on the Protodyakonov hardness coefficient of the ore. The upper limit of the Protodyakonov hardness coefficient of medium-hardness ore is 8. If the average Protodyakonov hardness coefficient of the ore is greater than 8, larger steel balls should be used; otherwise, smaller steel balls should be used.

[0022] Step 2: Calculate the cumulative mass of the corresponding size of steel ball required to add one steel ball of each size based on the grinding ball consumption. Weigh the steel balls of different sizes to obtain their weights. The mass of the corresponding size required to add one steel ball is the ratio of the weight of the steel ball of that size to the grinding ball consumption.

[0023] Step 3: While the ball mill is running normally, monitor the internal current in real time and record the ball mill current before and after adding supplementary balls. The ball mill current before adding supplementary balls is recorded as follows: The ball mill current was recorded after the addition of balls. To ensure accuracy, multiple records were taken and the average value was calculated. and , , and , All are within the rated operating current of the ball mill. and The result is a weighted average of three or more measurements, and the measured result is then sent to an automatic ball-adding machine.

[0024] Step 4: Actual current during ball mill operation and and In comparison, when ≤ ≤ When the cumulative mass of different particle sizes in the ore in step S1 is compared with the corresponding particle size mass calculated by adding one steel ball of a different size in step S2, if the mass is equal, add one steel ball of the corresponding size, then reset the cumulative mass of this particle size in the ore to zero and start accumulating again. ≤ At one time, a whole class's worth of steel balls were added at once. ≥ When ball feeding is stopped, the ball mill's operating current is monitored in real time, either after a one-time ball feeding or after ball feeding is stopped. The mass of different particle sizes in the feed ore in step S1 is accumulated using an electronic belt scale connected to an automatic ball feeder. Once the accumulated mass of the electronic belt scale reaches the corresponding particle size mass, the accumulated mass is reset to zero. The automatic ball feeder adds a steel ball of the corresponding particle size. The automatic ball feeder analyzes the data input from the electronic belt scale and the ball mill to control the number and particle size of the balls added. The mass of each size of steel ball added in one shift is the same. After calculating the number of steel balls of each size, they are added using the automatic ball feeder.

[0025] Step 5: Repeat step S4.

[0026] Experimental verification: The maximum particle size of the ball mill feed was selected as D95=19.50mm, the average hardness was 11.44, the ball mill specifications were MQG3.2×4.5m, the throughput was 65t / h, and the content of -0.074mm particle size in the overflow of the first-stage grinding classification was 65%.

[0027] The ball mill was used to add 416 kg of steel balls per shift, with a ratio of Φ100 mm: Φ80 mm: Φ60 mm = 30%: 30%: 40%, which is referred to as Comparative Example 1.

[0028] The processing and production using this method is denoted as Example 1. The specific steps are as follows:

[0029] Step 1: The ore is fed to the ball mill using high-frequency vibrating screens with diameters of 15mm, 8mm, and 2mm to separate it into +15mm, +8mm, +2mm, and -2mm particle sizes. During the transport of the different particle sizes to the ball mill via conveyor belt, an electronic belt scale is used to record their weights. Since the ore's Protodyakonov hardness coefficient of 11.44 is greater than that of medium-hardness ores (Protodyakonov hardness coefficient 8), the +15mm particle size is assigned 100mm diameter steel balls, the +8mm particle size is assigned 80mm diameter steel balls, the +2mm particle size is assigned 60mm diameter steel balls, and the -2mm particle size is assigned 50mm diameter steel balls.

[0030] Step 2: The on-site steel ball consumption is 0.8 kg / t, meaning that 0.8 kg of steel balls are needed to grind 1000 kg of ore. Calculations show that one 100mm steel ball weighs 4.1 kg, therefore adding one 100mm steel ball requires a cumulative weight of 5125 kg of +15mm ore; one 80mm steel ball weighs 2.1 kg, therefore adding one 80mm steel ball requires a cumulative weight of 2625 kg of +8mm ore; one 60mm steel ball weighs 0.88 kg, therefore adding one 60mm steel ball requires a cumulative weight of 1100 kg of +2mm ore; and one 50mm steel ball weighs 0.51 kg, therefore adding one 50mm steel ball requires a cumulative weight of 638 kg of -2mm ore.

[0031] Step 3: When the ball mill is running normally, record the ball mill current I1 before adding the balls as 77.83A, 77.50A, 77.33A, 77.67A, and 77.87A, respectively, so the average value of I1 is 77.64A; after adding the balls, record the ball mill current I2 as 79.43A, 78.80A, 78.57A, 78.55A, and 79.07A, so the average value of I2 is 78.88A.

[0032] Step 4: Compare the actual current during ball mill operation. The relationship between 77.64A and 78.88A, when 77.64A ≤ When the mass of the +15mm particle size reaches 5125 kg, add a 100mm steel ball; when the cumulative weight of the +8mm particle size reaches 2625 kg, add an 80mm steel ball; when the cumulative weight of the +2mm particle size reaches 1100 kg, add a 60mm steel ball; when the cumulative weight of the -2mm particle size reaches 637.5 kg, add a 50mm steel ball. After adding any size steel ball, the cumulative mass of the corresponding particle size in the ore is reset to zero and recalculated. When the alumina is ≤77.64A, the amount of steel balls added at one time for one shift is: 65t / h × 8h × 0.8kg / t = 416kg of steel balls, 104kg each of 100mm, 80mm, 60mm, and 50mm, including 25 100mm steel balls, 50 80mm steel balls, 119 60mm steel balls, and 203 50mm steel balls; when Stop adding balls when the current reaches ≥78.88A. Monitor the ball mill operating current in real time after adding or stopping balls in a single operation.

[0033] Step 5: Repeat step 4.

[0034] The ball mill is selected with a maximum feed particle size of D95=12.65mm, an average hardness of 9.61, a ball mill specification of MQG2.7×3.6m, a throughput of 35t / h, and an overflow fineness of 55% in the first stage of grinding and classification.

[0035] The ball mill was used to add 266 kg of steel balls per shift, with a ratio of Φ100 mm: Φ80 mm: Φ60 mm = 20%: 30%: 50%, which is referred to as Comparative Example 2.

[0036] The production process using this method is denoted as Example 2. The specific steps are as follows:

[0037] Step 1: The ore is fed to the ball mill using high-frequency vibrating screens with diameters of 10mm, 5mm, and 2mm to separate it into +10mm, +5mm, +2mm, and -2mm particle sizes. During the transport of the different particle sizes to the ball mill via conveyor belt, an electronic belt scale is used to record their weights. Since the ore's Protodyakonov hardness coefficient (9.61) is greater than that of medium-hardness ores (8), the +10mm particle size is assigned 90mm diameter steel balls, the +5mm particle size is assigned 70mm diameter steel balls, the +2mm particle size is assigned 60mm diameter steel balls, and the -2mm particle size is assigned 50mm diameter steel balls.

[0038] Step 2: The on-site steel ball consumption is 0.95 kg / t, meaning that 0.95 kg of steel balls are needed to grind 1000 kg of ore. Calculations show that one 90mm steel ball weighs 3.0 kg, therefore adding one 90mm steel ball requires a cumulative weight of 3160 kg of +10mm ore; one 70mm steel ball weighs 1.4 kg, therefore adding one 70mm steel ball requires a cumulative weight of 1470 kg of +5mm ore; one 60mm steel ball weighs 0.88 kg, therefore adding one 60mm steel ball requires a cumulative weight of 926 kg of +2mm ore; and one 50mm steel ball weighs 0.51 kg, therefore adding one 50mm steel ball requires a cumulative weight of 537 kg of -2mm ore.

[0039] Step 3: When the ball mill is running normally, record the ball mill current I1 before adding the balls as 22.8A, 22.2A, 22.5A, 22.3A, and 22.8A respectively, so the average value of I1 is 22.5A; after adding the balls, record the ball mill current I2 as 23.6A, 23.8A, 23.7A, 23.5A, and 23.7A respectively, so the average value of I2 is 23.7A.

[0040] Step 4: Compare the actual current during ball mill operation. The relationship between the magnitudes of 22.5A and 23.7A, when ≤ When the weight of +10mm particles reaches 3160 kg, add a 90mm steel ball; when the weight of +5mm particles reaches 1470 kg, add a 70mm steel ball; when the weight of +2mm particles reaches 926 kg, add a 60mm steel ball; when the weight of -2mm particles reaches 537 kg, add a 50mm steel ball. After adding any size steel ball, reset the cumulative mass of the corresponding particle size in the ore to zero and start accumulating again. When I ≤ 0.95 kg / h, add the required amount of steel balls for one shift at a time, specifically: 35 t / h × 8 h × 0.95 kg / t = 266 kg of steel balls, including 66.5 kg each of 90 mm, 70 mm, 60 mm, and 50 mm balls. Specifically, add 22 90 mm balls, 48 ​​70 mm balls, 75 60 mm balls, and 131 50 mm balls. Stop adding balls when I ≥ 0.95 kg / h. Monitor the ball mill's operating current in real time after each ball addition or stoppage.

[0041] Step 5: Repeat step 4.

[0042] After the grinding and classification systems of Examples 1 and 2 and Comparative Examples 1 and 2 stabilized, the ball mill throughput, steel ball consumption and current were statistically analyzed, the particle size composition of the grinding and classification products was examined, and the data were recorded in Table 1.

[0043] Table 1: Statistical Table of Grinding Indicators

[0044]

[0045] As can be seen from Table 1, under the same feed particle size and normal production conditions, the method adopted in this invention can significantly improve the particle size of the grinding product. At the same time, the processing capacity of this invention is higher, the consumption of steel balls and current is lower, and the content of medium-coarse grade +0.10mm, fine grade -0.074mm and intermediate easily sortable grade -0.10+0.010mm is reduced respectively.

[0046] In summary, this invention determines the quality of steel balls of different sizes by real-time measurement of the particle size distribution in the ball mill feed, thereby supplementing the grinding consumption of the ball mill. It also controls the steel ball filling rate within an appropriate range by monitoring changes in the ball mill current. This is a precise, fast, and effective method for judging the size and quality of added steel balls. This invention keeps the steel balls inside the ball mill in a balanced state, thereby improving grinding efficiency, stabilizing the particle size distribution of the ground product, and solving the problems of adding the size and quality of supplementary steel balls during ball mill production.

[0047] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, 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 determining the size and quantity of supplementary steel balls by measuring the feed particle size and current of a ball mill, characterized in that, Includes the following steps: S1. The ball mill feed is divided into 4-5 different particle sizes and the mass of each particle size is accumulated. Different sizes of steel balls are assigned to different particle sizes. S2. Calculate the cumulative particle size mass required to add one steel ball of each size based on the grinding ball consumption. S3. During normal operation of the ball mill, monitor the internal current in real time and record the ball mill current before and after adding supplementary balls. The ball mill current before adding supplementary balls is recorded as follows: The ball mill current was recorded after the addition of balls. To ensure accuracy, multiple records were taken and the average value was calculated. and ; S4. Actual current during ball mill operation and and In comparison, when ≤ ≤ When the cumulative mass of different particle sizes in the ore in step S1 is compared with the corresponding particle size mass calculated by adding one steel ball of a different size in step S2, if the mass is equal, add one steel ball of the corresponding size, then reset the cumulative mass of this particle size in the ore to zero and start accumulating again. ≤ At one time, a whole class's worth of steel balls were added at once. ≥ Stop adding balls when necessary, and monitor the ball mill's operating current in real time after adding balls all at once or stopping ball adding. S5. Repeat step S4.

2. The method for determining the size and quantity of supplementary steel balls by measuring the particle size of the ball mill feed and the current, as described in claim 1, is characterized in that: In step S1, the ball mill feed is screened into different particle sizes using a high-frequency vibrating screen. The screen aperture sizes of the high-frequency vibrating screen include 15mm, 10mm, 8mm, 5mm, and 2mm. The ball mill feed is divided into +15mm, +10mm, +8mm, +5mm, +2mm, and -2mm particle sizes. The number of screen layers and screen aperture sizes are selected according to the particle size composition of the ball mill feed, and the yield of each particle size is controlled between 20% and 50%.

3. The method for determining the size and quantity of supplementary steel balls by measuring the particle size of the ball mill feed and the current, as described in claim 1, is characterized in that: In step S1, 90mm and 100mm steel balls are assigned to the +15mm particle size, 80mm and 90mm steel balls to the +10mm particle size, 70mm and 80mm steel balls to the +8mm particle size, 60mm and 70mm steel balls to the +5mm particle size, 50mm and 60mm steel balls to the +2mm particle size, and 40mm and 50mm steel balls to the -2mm particle size. The size of the steel balls assigned for each particle size should be based on the Protodyakonov hardness coefficient of the ore. The upper limit of the Protodyakonov hardness coefficient of medium-hardness ore is 8. If the average Protodyakonov hardness coefficient of the ore is greater than 8, a larger steel ball should be used; otherwise, a smaller steel ball should be used.

4. The method for determining the size and quantity of supplementary steel balls by measuring the particle size of the ball mill feed and the current, as described in claim 1, is characterized in that: In step S2, the weights of steel balls of different sizes are obtained by weighing. The mass of the corresponding particle size required to add one steel ball is the ratio of the weight of the steel ball of that size to the consumption of grinding balls.

5. The method for determining the size and quantity of supplementary steel balls by measuring the particle size of the ball mill feed and the current, as described in claim 1, is characterized in that: In step S3, , and , All are within the rated operating current of the ball mill. and The result is a weighted average of three or more measurements, and the measured result is sent to the automatic ball-adding machine.

6. The method for determining the size and quantity of supplementary steel balls by measuring the particle size of the ball mill feed and the current, as described in claim 1, is characterized in that: In step S4, the mass of different particle sizes in the feed ore from step S1 is accumulated using an electronic belt scale. The electronic belt scale is connected to an automatic ball feeder. Once the accumulated mass of the electronic belt scale reaches the corresponding particle size mass, the accumulated mass is reset to zero. The automatic ball feeder adds a steel ball of the corresponding particle size. The automatic ball feeder analyzes the data input from the electronic belt scale and the ball mill to control the number and particle size of the balls added.

7. The method for determining the size and quantity of supplementary steel balls by measuring the particle size of the ball mill feed and the current, as described in claim 1, is characterized in that: In step S4, steel balls of each size with the same mass are added to a shift. After calculating the number of steel balls of each size, an automatic ball-adding machine is used to add them.

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