Method for determining size and number of supplemented steel balls by measuring feeding granularity and current of ball mill

Abstract

The invention discloses a method for determining the size and quantity of supplemented steel balls by measuring the feeding granularity and current of a ball mill, which comprises the following steps: S1, dividing the feeding of the ball mill into 4-5 different size fractions, accumulating the mass of each fraction, and distributing the steel balls with different sizes to the different size fractions; s2, according to the ore grinding ball consumption, the corresponding size fraction mass needing to be accumulated when one steel ball is added to each size of steel ball is calculated; s3, monitoring the internal current in real time when the ball mill normally operates, and recording the current of the ball mill before and after adding the supplementary ball; s4, comparing the actual current I with the I1 and the I2 in the running process of the ball mill; and S5, repeating the step S4. The content of each fraction in the feeding granularity of the ball mill is measured in real time, and the steel ball filling rate of the ball mill is controlled within a proper range through the current change of the ball mill, so that the steel balls in the ball mill are in a balanced state, the grinding efficiency of the ball mill is improved, and the granularity composition of a ground product is stabilized.

Description

Technical Field

[0001] The invention relates to the technical field of automatic control of ore grinding, in particular to a method for determining the size and quantity of additional steel balls by measuring the ore feed particle size and current of a ball mill. Background Art

[0002] In a mineral processing plant, the overflow from grinding and grading directly enters the subsequent separation operation, and its quality directly affects the indicators of the separation operation. The coarse particles that are not dissociated in the overflow are not conducive to the recovery of valuable elements. Even if they are successfully recovered, the grade of the concentrate will be reduced. The over-dissociated fine particles not only cause excessive consumption of electricity and steel, but also have an adverse effect on subsequent flotation and dehydration operations. At the same time, the working efficiency of the ball mill actually determines the processing capacity of the mineral processing plant.

[0003] In the prior art, the size and quality of steel balls in the ball mill 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 supplementation plan, the size and quantity of steel balls added to the subsequent production ball mill are fixed, and the need for additional steel balls is determined based on the swelling of the ball mill and the particle size composition of the grinding product, which seriously affects the working efficiency of the ball mill. Therefore, a perfect steel ball supplementation system is needed to improve the working efficiency of the ball mill. Summary of the invention

[0004] The purpose of the present invention is to provide a method for determining the size and quantity of additional steel balls by measuring the feed particle size and current of the ball mill, so as to solve the problem that the size and quality of the steel balls in the ball mill are affected by many factors, among which the size of the feed particle size, the content of each particle grade and the mechanical properties of the ore are more important. After the designers determine the plan for adding steel balls, the size and quantity of steel balls added to the subsequent production ball mill are fixed, and it is judged whether the ball mill needs additional steel balls according to the swelling of the ball mill and the particle size composition of the grinding product, which seriously affects the working efficiency of the ball mill. Therefore, a perfect steel ball addition system is needed to improve the working efficiency of the ball mill.

[0005] To achieve the above object, the present invention provides the following technical solution: a method for determining the size and quantity of additional 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 size grades and the mass of each grade is accumulated. Different sizes of steel balls are allocated to different size grades.

[0007] S2. Calculate the corresponding size particle mass required to add one steel ball of each size according to the grinding ball consumption;

[0008] S3. When the ball mill is running normally, monitor the internal current in real time and record the current of the ball mill before and after adding the balls. The current of the ball mill before adding the balls is recorded as I1, and the current of the ball mill after adding the balls is recorded as I2. To ensure accuracy, multiple records can be made to obtain the average value. and

[0009] S4. During the operation of the ball mill, the actual current I and For comparison, When the accumulative mass of different particle sizes of the ore in step S1 is compared with the mass of the corresponding particle size calculated by adding a steel ball of different sizes in step S2, if it reaches the mass, add a steel ball of the corresponding size, then reset the accumulative mass of this particle size in the ore, and re-accumulate it. When adding a shift of additional steel balls at a time, Stop adding balls at the right time, add balls at one time or stop adding balls and monitor the ball mill operating current in real time;

[0010] S5. Repeat step S4.

[0011] Preferably, in step S1, the ball mill feed is screened into different size fractions using a high-frequency vibrating screen, and the sieve hole 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 fractions. The number of screen layers and the sieve hole 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, +15mm particle size is allocated to 90mm and 100mm steel balls, +10mm particle size is allocated to 80mm and 90mm steel balls, +8mm particle size is allocated to 70mm and 80mm steel balls, +5mm particle size is allocated to 60mm and 70mm steel balls, +2mm particle size is allocated to 50mm and 60mm steel balls, -2mm particle size is allocated to 40mm and 50mm steel balls, and the size of steel balls allocated to each size particle size needs to refer to the Pu's hardness coefficient of the ore, with the upper limit of 8 of the Pu's hardness coefficient of medium hardness ore as the limit, and the average Pu's hardness coefficient of the ore is greater than 8. Large-sized steel balls are used as the appropriate steel balls, otherwise small-sized steel balls are used.

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

[0014] Preferably, in step S3, I1, and I2, All are within the rated operating current of the ball mill. and It is the weighted average of more than three times, and the measured results are transmitted to the automatic ball adding machine.

[0015] Preferably, in step S4, the masses of different particle sizes in the ore fed in step S1 are accumulated using an electronic belt scale, the electronic belt scale is connected to an automatic ball adding machine, the accumulated mass of the electronic belt scale is reset to zero after the accumulated mass reaches the mass of the corresponding particle size, and the automatic ball adding machine adds a steel ball of the corresponding particle size, the automatic ball adding machine analyzes the data input by the electronic belt scale and the ball mill, thereby controlling the number of balls added and the particle size.

[0016] Preferably, in step S4, the steel balls added in one shift have the same mass for each size, and the number of steel balls for each size is calculated and then added using an automatic ball adding machine.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] In the present invention, the content of each particle size in the ball mill feed particle size is measured in real time to determine the quality of additional steel balls of different sizes, so as to supplement the grinding consumption of the ball mill. The filling rate of the steel balls in the ball mill is controlled within an appropriate range through the change of the ball mill current. This is an accurate, fast and effective method for judging the size and quality of additional steel balls. The present invention enables the steel balls inside the ball mill to be in a balanced state, thereby improving the grinding efficiency of the ball mill, stabilizing the particle size composition of the grinding product, and solving the problem of the size and quality of additional balls added in the production process of the ball mill. DETAILED DESCRIPTION

[0019] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the implementation regulations described 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 work are within the scope of protection of the present invention.

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

[0021] Step 1: Divide the ball mill feed into 4-5 different size fractions and accumulate the mass of each fraction. Allocate different size steel balls to different size fractions. Use high-frequency vibrating screen to screen the ball mill feed into different size fractions. The mesh size of the high-frequency vibrating screen includes 15mm, 10mm, 8mm, 5mm, and 2mm. Divide the ball mill feed into +15mm, +10mm, +8mm, +5mm, +2mm, and -2mm fractions. Select the number of screen layers and mesh size according to the particle size composition of the ball mill feed. The yield of each fraction is controlled between 20% and 50%. The +15mm fraction is allocated 90mm and 100mm steel balls, +10mm grade is allocated to 80mm and 90mm steel balls, +8mm grade is allocated to 70mm and 80mm steel balls, +5mm grade is allocated to 60mm and 70mm steel balls, +2mm grade is allocated to 50mm and 60mm steel balls, -2mm grade is allocated to 40mm and 50mm steel balls. The size of steel balls allocated for each size grade should refer to the Pu's hardness coefficient of the ore. The upper limit of the Pu's hardness coefficient of the medium hardness ore is 8. If the average Pu's hardness coefficient of the ore is greater than 8, a large-sized steel ball is suitable, otherwise a small-sized steel ball is used;

[0022] Step 2: Calculate the mass of the corresponding size grade required to add one steel ball of each size according to the grinding ball consumption, weigh the weight of steel balls of different sizes, and the mass of the corresponding grade required to add one steel ball is the ratio of the weight of the steel ball of that size to the grinding steel consumption;

[0023] Step 3: When the ball mill is running normally, monitor the internal current in real time and record the current of the ball mill before and after adding the balls. The current of the ball mill before adding the balls is recorded as I1, and the current of the ball mill after adding the balls is recorded as I2. To ensure accuracy, multiple records can be made to obtain the average value. and I1. and I2, All are within the rated operating current of the ball mill. and It is the weighted average of more than three times, and the measured results are transmitted to the automatic ball adding machine;

[0024] Step 4: The actual current I and and For comparison, When the accumulative mass of different particle sizes of the ore in step S1 is compared with the mass of the corresponding particle size calculated by adding a steel ball of different sizes in step S2, if it reaches the mass, add a steel ball of the corresponding size, then reset the accumulative mass of this particle size in the ore, and re-accumulate it. When adding a shift of additional steel balls at a time, Stop adding balls when the ball mill is stopped. After adding balls once or stopping adding balls, monitor the operating current of the ball mill in real time. Use an electronic belt scale to accumulate the masses of different particle sizes in the ore fed in step S1. The electronic belt scale is connected to the automatic ball adding machine. After the accumulated mass of the electronic belt scale reaches the mass of the corresponding particle size, the accumulated mass is reset to zero. The automatic ball adding machine adds a steel ball of the corresponding particle size. The automatic ball adding machine analyzes the data input by the electronic belt scale and the ball mill to control the number of balls added and the particle size. The steel balls added in one shift have the same mass of each size. After calculating the number of steel balls of each size, the automatic ball adding machine is used to add them.

[0025] Step 5: Repeat step S4.

[0026] Test verification: The maximum particle size of the ball mill feed is D95 = 19.50mm, the average hardness is 11.44, the ball mill specification is MQG3.2×4.5m, the processing capacity is 65t / h, and the first-stage grinding classification overflow -0.074mm particle content is 65%;

[0027] The ball mill is used to add 416 kg of steel balls in each shift, and the ratio is: Φ100 mm: Φ80 mm: Φ60 mm = 30%: 30%: 40% to produce, which is recorded as Comparative Example 1;

[0028] This method is used for processing and production, which is recorded as Example 1. The specific steps are:

[0029] Step 1: Use 15mm, 8mm and 2mm high-frequency vibrating screens to screen the ore fed to the ball mill into +15mm, +8mm, +2mm and -2mm particle sizes. After screening different particle sizes, use an electronic belt scale to count the weights of each particle size during the transportation to the ball mill on the belt. Since the Pu's hardness coefficient of the ore is 11.44, which is greater than the Pu's hardness coefficient of the medium hardness ore of 8, the +15mm particle size is allocated with a 100mm diameter steel ball, the +8mm particle size is allocated with a 80mm diameter steel ball, the +2mm particle size is allocated with a 60mm diameter steel ball, and the -2mm particle size is allocated with a 50mm diameter steel ball.

[0030] Step 2. The unit consumption of steel balls on site is 0.8kg / t, that is, 0.8kg of steel balls are needed for every 1000kg of ore ground. Calculation shows that the weight of a 100mm steel ball is 4.1kg, so the cumulative weight of +15mm ore when adding a 100mm steel ball is 5125kg; the weight of an 80mm steel ball is 2.1kg, so the cumulative weight of +8mm ore when adding an 80mm steel ball is 2625kg; the weight of a 60mm steel ball is 0.88kg, so the cumulative weight of +2mm ore when adding a 60mm steel ball is 1100kg; the weight of a 50mm steel ball is 0.51kg, so the cumulative weight of -2mm ore when adding a 50mm steel ball is 638kg.

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

[0032] Step 4. Compare the actual current I during the operation of the ball mill with 77.64A and 78.88A. When 77.64A≤I≤78.88A, when the cumulative weight 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 of steel ball, the cumulative mass of the corresponding particle size in the ore is reset to zero and accumulated again. When I≤77.64A, add the amount of steel balls for one shift at one time, specifically: 65t / h×8h×0.8kg / t=416kg steel balls, 104kg for 100mm, 80mm, 60mm, 50mm, including 25 100mm steel balls, 50 80mm steel balls, 119 60mm steel balls, 203 50mm steel balls; stop adding balls when I≥78.88A. Monitor the operating current of the ball mill in real time after adding balls at one time or stopping the balls.

[0033] Step 5. Repeat step 4.

[0034] Select the maximum particle size of the ball mill feed D95 ​​= 12.65mm, the average hardness is 9.61, the ball mill specification is MQG2.7×3.6m, the processing capacity is 35t / h, and the overflow fineness in the first stage grinding classification is 55%;

[0035] The ball mill is used to add 266 kg of steel balls in each shift, and the ratio is: Φ100 mm: Φ80 mm: Φ60 mm = 20%: 30%: 50% to produce, which is recorded as Comparative Example 2;

[0036] This method is used for production, which is recorded as Example 2. The specific steps are:

[0037] Step 1: Use 10mm, 5mm and 2mm high-frequency vibrating screens to screen the ore fed to the ball mill into +10mm, +5mm, +2mm and -2mm particle sizes. After screening different particle sizes, use an electronic belt scale to count the weights of each particle size during the transportation to the ball mill on the belt. Since the Pu's hardness coefficient of the ore is 9.61, which is greater than the Pu's hardness coefficient of the medium hardness ore of 8, the +10mm particle size is allocated with a 90mm diameter steel ball, the +5mm particle size is allocated with a 70mm diameter steel ball, the +2mm particle size is allocated with a 60mm diameter steel ball, and the -2mm particle size is allocated with a 50mm diameter steel ball.

[0038] Step 2. The unit consumption of steel balls on site is 0.95kg / t, that is, 0.95kg of steel balls are required for every 1000kg of ore ground. Calculation shows that the weight of a 90mm steel ball is 3.0kg, so adding a 90mm steel ball requires a cumulative weight of +10mm ore of 3160kg; the weight of a 70mm steel ball is 1.4kg, so adding a 70mm steel ball requires a cumulative weight of +5mm ore of 1470kg; the weight of a 60mm steel ball is 0.88kg, so adding a 60mm steel ball requires a cumulative weight of +2mm ore of 926kg; the weight of a 50mm steel ball is 0.51kg, so adding a 50mm steel ball requires a cumulative weight of -2mm ore of 537kg.

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

[0040] Step 4. Compare the actual current I during the operation of the ball mill with 22.5A and 23.7A. When ≤I≤, when the cumulative weight of the +10mm particle size reaches 3160 kg, add a 90mm steel ball; when the cumulative weight of the +5mm particle size reaches 1470 kg, add a 70mm steel ball; when the cumulative weight of the +2mm particle size reaches 926 kg, add a 60mm steel ball; when the cumulative weight of the -2mm particle size reaches 537 kg, add a 50mm steel ball. After adding steel balls of any size, the cumulative mass of the corresponding particle size in the ore is reset to zero and accumulated again. When I≤, add the amount of steel balls for one shift at one time, specifically: 35t / h×8h×0.95kg / t=266kg steel balls, 66.5kg for 90mm, 70mm, 60mm, and 50mm, including 22 90mm steel balls, 48 ​​70mm steel balls, 75 60mm steel balls, and 131 50mm steel balls. When I≥, stop adding balls. Monitor the operating current of the ball mill in real time after adding balls at one time or stopping.

[0041] Step 5. Repeat step 4.

[0042] After the grinding and classification systems of Example 1 and Example 2 and Comparative Example 1 and Comparative Example 2 are stable, the ball mill processing capacity, steel ball consumption and current are counted, and the particle size composition of the grinding and classification products is investigated. The data are recorded in Table 1.

[0043] Table 1: Grinding index statistics

[0044] index Example 1 Example 2 Comparative Example 1 Comparative Example 2 Processing capacity t / h 65.95 36.13 65.04 34.77 Steel ball consumption / kg / t 0.807 0.89 0.836 0.95 Current / A 78.18 22.38 79.60 23.56 +0.10mm / % 20.58 21.77 27.59 30.97 -0.074mm / % 71.45 57.12 64.09 50.61 -0.10+0.010mm / % 53.59 63.84 49.66 58.27

[0045] It can be seen from Table 1 that under the condition of normal production with the same feed particle size, the method adopted by the present invention can significantly improve the particle size of the grinding product. At the same time, the processing capacity of the present invention is higher, the steel ball consumption and current are lower, and the contents of the medium-coarse grade +0.10mm, fineness -0.074mm and intermediate easy-selection grade -0.10+0.010mm are respectively reduced.

[0046] In summary, the present invention determines the problem of the quality of additional steel balls of different sizes by real-time measuring the content of each particle size in the ball mill feed particle size, so as to supplement the grinding consumption of the ball mill, and controls the filling rate of the steel balls of the ball mill within an appropriate range through the change of the ball mill current. It is an accurate, fast and effective method for judging the size and quality of additional steel balls. The present invention puts the steel balls inside the ball mill in a balanced state, thereby improving the grinding efficiency of the ball mill, stabilizing the particle size composition of the grinding product, and solving the problem of the size and quality of additional balls added in the production process of the ball mill.

[0047] Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments, or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for determining the size and quantity of additional steel balls by measuring the feed particle size and current of a ball mill, characterized in that: The following steps are involved: S1. The ball mill feed is divided into 4-5 different size grades and the mass of each grade is accumulated. Different sizes of steel balls are allocated to different size grades. S2. Calculate the corresponding size particle mass required to add one steel ball of each size according to the grinding ball consumption; S3. When the ball mill is operating normally, the internal current is monitored in real time, and the current of the ball mill before and after the additional balls are added is recorded, wherein the current of the ball mill before the additional balls are added is recorded as I1, and the current of the ball mill after the additional balls are added is recorded as I2. To ensure accuracy, the average values ​​I1 and I2 can be obtained by multiple recordings; S4. During the operation of the ball mill, the actual current I is compared with I1 and I2. When I1≤I≤I2, the cumulative mass of different size fractions of the ore in step S1 is compared with the mass of the corresponding size fraction calculated by adding a steel ball of different size in step S2. If it reaches the value, add a steel ball of the corresponding size, then reset the cumulative mass of this particle fraction in the ore, and accumulate again. When I≤I1, add the steel balls added in one shift at a time. When I≥I2, stop adding balls. After adding balls at one time or stopping adding balls, monitor the operating current of the ball mill in real time. S5. Repeat step S4.

2. The method for determining the size and quantity of additional steel balls by measuring the feed particle size and current of the ball mill according to claim 1, characterized in that: In step S1, the ball mill feed is screened into different size fractions using a high-frequency vibrating screen. The screen hole 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 fractions. The number of screen layers and the size of the screen holes are selected according to the particle size composition of the ball mill feed. The yield of each fraction is controlled between 20% and 50%.

3. The method for determining the size and quantity of additional steel balls by measuring the feed particle size and current of the ball mill according to claim 1, characterized in that: In step S1, +15mm particle size is allocated to 90mm and 100mm steel balls, +10mm particle size is allocated to 80mm and 90mm steel balls, +8mm particle size is allocated to 70mm and 80mm steel balls, +5mm particle size is allocated to 60mm and 70mm steel balls, +2mm particle size is allocated to 50mm and 60mm steel balls, -2mm particle size is allocated to 40mm and 50mm steel balls. The size of steel balls allocated to each size particle size needs to refer to the Pu's hardness coefficient of the ore. The upper limit of the Pu's hardness coefficient of the medium hardness ore is 8. If the average Pu's hardness coefficient of the ore is greater than 8, large-sized steel balls are used as the appropriate steel balls, otherwise small-sized steel balls are used.

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

5. The method for determining the size and quantity of additional steel balls by measuring the feed particle size and current of a ball mill according to claim 1, characterized in that: In step S3, I1, I1 and I2, I2 are all within the rated operating current of the ball mill, I1 and I2 are weighted averages of more than three times, and the measured results are transmitted to the automatic ball adding machine.

6. The method for determining the size and quantity of additional steel balls by measuring the feed particle size and current of a ball mill according to claim 1, characterized in that: In step S4, the masses of different particle sizes in the ore fed in step S1 are accumulated using an electronic belt scale, which is connected to an automatic ball adding machine. When the accumulated mass of the electronic belt scale reaches the mass of the corresponding particle size, the accumulated mass is reset to zero, and the automatic ball adding machine adds a steel ball of the corresponding particle size. The automatic ball adding machine analyzes the data input by the electronic belt scale and the ball mill to control the number of balls added and the particle size.

7. The method for determining the size and quantity of additional steel balls by measuring the feed particle size and current of a ball mill according to claim 1, characterized in that: In step S4, the steel balls added in one shift have the same mass for each size, and the number of steel balls of each size is calculated and then added using an automatic ball adding machine.