Method for controlling the filling rate of steel balls in semi-autogenous grinding mill

Abstract

The present invention discloses a method for controlling the steel ball filling rate of a semi-autogenous mill, comprising: calculating the steel ball filling rate Φ after the semi-autogenous mill has been running for a period of time t according to the formula, Φ=100%×(M q +M d ‑M x ‑M t ) / (M max / Φ max );M q M is the total mass of the steel balls before running for a certain time; d M is the total mass of the steel balls added during the running time t; x M is the total mass of steel balls consumed during the running time t; t M is the total mass of steel balls ejected during the running time t; max is the maximum steel ball filling mass; Φ max The method for controlling the steel ball filling rate of a semi-autogenous mill provided by the present invention can accurately obtain the steel ball filling rate in the semi-autogenous mill without stopping the mill, and control the steel ball filling rate in real time.

Description

Technical Field

[0001] The present invention relates to the technical field of grinding, in particular to a method for controlling the steel ball filling rate of a semi-autogenous grinding mill. Background Art

[0002] During mining operations, crushers are used to break raw ore into a specific particle size. Mills then pulverize the ore into fine particles for subsequent processing. Depending on the grinding medium, mills are categorized into ball mills, rod mills, pebble mills, autogenous mills, and semi-autogenous mills. Ball mills and semi-autogenous mills are the most widely used, utilizing the impact and grinding action of steel balls within the mill to crush the ore. A certain amount of steel balls, or a certain ball filling ratio, must be maintained within the mill. Excessive or insufficient steel balls can negatively impact mill performance, especially in semi-autogenous mills. Because semi-autogenous mills have larger cylinder diameters and are equipped with steel liners, larger steel balls are added and then lifted to a certain height using the mill's lifting bars, leveraging their potential energy to impact and grind the ore. Therefore, controlling the ball filling ratio in semi-autogenous mills is crucial during production.

[0003] In the actual production process of a SAG mill, the optimal steel ball filling rate is related to the properties of the ore and the state of the mill. The harder the ore, the higher the steel ball filling rate needs to be; conversely, the lower the steel ball filling rate needs to be. A high steel ball filling rate not only increases the unit consumption of steel balls and costs, but also easily impacts the SAG mill's steel liner, causing cracks and damage to the mill. A low steel ball filling rate affects the SAG mill's grinding effect and processing capacity, and the SAG mill is prone to bloating. Because the steel ball filling rate in a SAG mill changes dynamically over time, controlling the appropriate steel ball filling rate for the SAG mill based on the properties of the ore is crucial for efficient ore processing.

[0004] Existing methods for obtaining the steel ball filling rate in a semi-autogenous mill usually require stopping the mill for measurement. However, stopping the mill to measure the steel ball filling rate accurately has the following problems: on the one hand, because the mill is a large-scale equipment, frequent opening can easily damage the mill. On the other hand, frequent opening of the semi-autogenous mill affects production. Therefore, in actual production processes, large mills cannot be frequently stopped and started and emptied of materials. The steel ball filling rate of the semi-autogenous mill can only be measured by emptying the materials when the mill is shut down, such as during regular maintenance. Therefore, it is necessary to accurately obtain the steel ball filling rate of the semi-autogenous mill without stopping the mill, track and calculate the real-time steel ball filling rate of the semi-autogenous mill, and facilitate timely adjustment to keep the steel ball filling rate of the semi-autogenous mill in a better state. Summary of the Invention

[0005] The present invention provides a method for controlling the steel ball filling rate of a semi-autogenous grinding mill, so as to solve the technical problem that the prior art cannot accurately obtain the steel ball filling rate in the semi-autogenous grinding mill without stopping the mill and cannot control the steel ball filling rate in real time.

[0006] The present invention provides a method for controlling the steel ball filling rate of a semi-autogenous mill, comprising the following steps: (1) calculating the steel ball filling rate after the semi-autogenous mill has been running for a time period t according to Formula 1,

[0007] Φ=100%×(M q +M d -M x -M t ) / (M max / Φ max ), Formula 1;

[0008] Among them, 4h≤t≤48h; M q M is the total mass of the steel balls before running for a certain time; d M is the total mass of the steel balls added during the running time t; x M is the total mass of steel balls consumed during the running time t; t M is the total mass of steel balls ejected during the running time t; max is the maximum steel ball filling mass; Φ max is the maximum filling rate, in %;

[0009] (2) Compare the calculated steel ball filling rate with the preset optimal filling rate and adjust the number of steel balls so that the steel ball filling rate is close to or equal to the preset optimal filling rate.

[0010] Further, the total mass M of the steel balls before the running time t is obtained q include:

[0011] Get the ball filling rate Φ before the SAG mill runs for a certain time t q ;

[0012] Calculate the total mass M of the steel balls before the SAG mill starts running according to Formula 2 q ,

[0013] M q =100×Φ q ×[M max / (100×Φ max )], formula 2;

[0014] Among them, Φ q The unit is %.

[0015] Furthermore, the steel ball filling rate Φ before the SAG mill runs for a certain time t is obtained. qThe ball mill cavity of the semi-autogenous mill is spherical. If the semi-autogenous mill is in a stopped state before the running time t, the circular cross section passing through the center of the ball and perpendicular to the ground is used as the calculation basis, and the area is recorded as S; the shaded area in the circular cross section represents the area covered by the steel ball, and the area is recorded as S1, Φ q =S1 / S.

[0016] Furthermore, the S1=S s -S t , where S s is the sector area corresponding to the shaded area in the circular cross section; S t It is the area of the triangle formed by connecting the endpoints of the shaded area within the circular cross section and the center of the circle.

[0017] Furthermore, the steel ball filling rate Φ before the SAG mill runs for a certain time t is obtained. q Including: If the semi-autogenous grinding mill is in operation for the first time t, then Φ q The Φ value to be calculated is obtained using Formula 1.

[0018] Furthermore, M x =T×K, where T is the total mass of ore processed within the running time t; K is the mass of steel balls consumed per unit mass of ore.

[0019] Furthermore, M t =n·ρ·4 / 3·π·(d / 2)3, where n is the number of balls ejected during the running time t, and ρ is the density of the steel balls in kg / m 3 ; d is the average diameter of the spit ball, in m.

[0020] Furthermore, during the operation of the SAG mill, the diameter of some worn steel balls becomes smaller and they are ejected through the holes of the gravel discharge grid plate of the SAG mill. The average diameter of the ejected balls is smaller than the hole diameter of the gravel discharge grid plate of the SAG mill.

[0021] Furthermore, the preset optimal filling rate is 1-14%.

[0022] Furthermore, before step (1), the method further includes: preliminarily judging whether it is necessary to add steel balls based on the content of stubborn stone in the ore in the semi-autogenous mill and the sound frequency of the semi-autogenous mill.

[0023] The present invention has the following beneficial effects:

[0024] The method for controlling the filling rate of steel balls in a semi-autogenous mill provided by the present invention can accurately obtain the filling rate of steel balls in the semi-autogenous mill without stopping the semi-autogenous mill, and control the filling rate of steel balls in real time. The method is applicable to the actual production control process of the semi-autogenous mill. Specifically, according to the total mass of the original steel balls (the total mass of the steel balls before the running time t, M q), the total mass of the newly added steel balls (M d ), running time t, the mass of steel balls consumed in the internal grinding mill (M x ), the mass of the ball ejected during the running time t (M t ), and the maximum ball filling mass (M max ) and maximum filling rate (Φ max ) to calculate the steel ball filling rate after the SAG mill has run for a certain time (t) to understand the real-time steel ball filling situation in the SAG mill during actual production. By comparing the calculated steel ball filling rate with the preset optimal filling rate, the number of steel balls is adjusted or kept unchanged to ensure that the steel ball filling rate is close to or equal to the preset optimal filling rate, thereby achieving the best ball milling effect.

[0025] The implementation of this technical solution allows for the adjustment of different grinding process conditions based on the properties of the ore. Different grinding processes involve different ball addition methods, ball discharge sizes, and ball consumption. By adjusting the various parameters in the formula, the real-time ball filling rate in the mill can be calculated with high accuracy.

[0026] In addition to the above-described objects, features and advantages, the present invention has other objects, features and advantages. The present invention will be further described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The accompanying drawings, which constitute part of this application, are intended to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are intended to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0028] Figure 1 2. It is a schematic diagram of a circular cross section of a semi-autogenous mill cavity according to a preferred embodiment of the present invention;

[0029] Figure 2 1. It is a structural diagram of a discharge grate plate of a semi-autogenous grinding mill according to a preferred embodiment of the present invention.

[0030] Legend:

[0031] 1-circular cross section; 2-shaded area. DETAILED DESCRIPTION

[0032] In order to make the invention purpose, technical scheme and beneficial technical effect of the present invention clearer, the present invention is further described in detail below with reference to the embodiments. It should be understood that the embodiments described in this specification are only for explaining the present invention and are not intended to limit the present invention.

[0033] For simplicity, only some numerical ranges are explicitly disclosed herein. However, any lower limit can be combined with any upper limit to form an unspecified range; and any lower limit can be combined with other lower limits to form an unspecified range, and similarly, any upper limit can be combined with any other upper limit to form an unspecified range. In addition, although not explicitly stated, each point or individual value between the endpoints of a range is included in the range. Thus, each point or individual value can serve as its own lower limit or upper limit and be combined with any other point or individual value, or with other lower limits or upper limits, to form an unspecified range.

[0034] In the description of this article, it should be noted that, unless otherwise specified, "above" and "below" are inclusive of the number itself, and the "multiple" in "one or more" means two or more, and the "multiple" in "one or more" means two or more.

[0035] The embodiment of the present application provides a method for controlling the steel ball filling rate of a semi-autogenous grinding mill, comprising the following steps:

[0036] (1) Calculate the steel ball filling rate after the semi-autogenous grinding mill has been running for a period of time t according to formula 1:

[0037] Φ=100%×(M q +M d -M x -M t ) / (M max / Φ max ), Formula 1;

[0038] Among them, 4h≤t≤48h; M q M is the total mass of the steel balls before running for a certain time; d M is the total mass of the steel balls added during the running time t; x M is the total mass of steel balls consumed during the running time t; t M is the total mass of steel balls ejected during the running time t; max is the maximum steel ball filling mass; Φ max is the maximum filling rate, in %;

[0039] (2) Compare the calculated steel ball filling rate with the preset optimal filling rate and adjust the number of steel balls so that the steel ball filling rate is close to or equal to the preset optimal filling rate.

[0040] In actual production processes, large grinding mills cannot be frequently stopped and started, and materials cannot be emptied. The steel ball filling rate of the semi-autogenous grinding mill can only be measured by emptying the materials when the mill is shut down for regular maintenance. In addition, the same type of grinding mill processes different types of ores, requiring different grinding processes and different grinding process parameters, such as grinding concentration, grinding fineness, processing capacity, steel ball filling rate, gravel removal grid size, steel ball adding method, etc., and the wear conditions of the steel balls in the mill are different. The present invention provides a method for regulating the steel ball filling rate of a semi-autogenous grinding mill, which calculates the steel ball filling rate in the semi-autogenous grinding mill of different grinding processes at all times, understands the status of the steel balls in the mill, and adjusts the parameters of the formula according to different grinding process conditions to ensure the accuracy of the calculation. Next, the calculated real-time steel ball filling rate is compared with the preset optimal filling rate, and the number of steel balls is adjusted so that the steel ball filling rate is close to or equal to the preset optimal filling rate.

[0041] The control method provided by the present invention can be applied to different grinding processes, that is, the method can run through the entire grinding process control process under different circumstances, and adapt to different grinding process conditions by adjusting different parameters in the calculation method, that is, this method can adapt to different production conditions of the mill.

[0042] It should be noted that in step (1), M q 、M d 、M x 、M t and M max The units must be unified, for example, they can be kg or g.

[0043] In an embodiment of the present application, in step (2), the calculated steel ball filling rate is compared with a preset optimal filling rate, and the number of steel balls is adjusted so that the steel ball filling rate is close to or equal to the preset optimal filling rate. For example, when the calculated steel ball filling rate is greater than the preset optimal filling rate, the number of steel balls is appropriately reduced; or when the calculated steel ball filling rate is less than the preset optimal filling rate, the number of steel balls is appropriately reduced; or when the calculated steel ball filling rate is equal to the preset optimal filling rate, the number of steel balls remains unchanged (in this case, it can be understood that the adjustment range in "adjusting the number of steel balls" is 0).

[0044] In the embodiments of the present application, T can be 4h, 8h, 12h, 24h, 36h or 48h, etc. Taking the duration t as one day (24h) as an example, the specific calculation formula is: filling rate = 100%·mass of steel balls in the mill on that day / (maximum amount of steel balls in the mill / maximum filling rate of the mill) = 100%·(mass of steel balls on the previous day + mass of newly added steel balls on that day - mass of steel balls consumed on that day - mass of balls discharged on that day) / (maximum amount of steel balls in the mill / maximum filling rate of the mill). Among them: ① Calculation of mass of balls discharged on that day, M t=n·ρ·4 / 3·π·(d / 2)3, where n is the number of balls ejected per day and ρ is the density of the steel balls, for example, ρ = 7.5 kg / m 3 , d is the average cumulative diameter of the balls, the diameter of the balls is related to the aperture of the grid plate of the semi-autogenous grinding mill and needs to be updated every day. ②The mass of steel balls consumed on the day, M x =T·K, where T is the ore processing volume of the day, and K is the average cumulative unit consumption of the ore. This is mainly related to the properties of the ore and the operating conditions of the mill. It is necessary to know the average cumulative unit consumption of steel balls for processing the ore, which needs to be determined according to actual production conditions; ③M max Design the maximum steel ball filling amount for the semi-autogenous grinding mill, for example, 168kg; ④Φ max , Φ are the maximum filling rate of SAG mill, 15%, and SAG mill filling rate respectively; ⑤M d The mass of the steel balls added on the day can be determined based on the number of balls added or the number of barrels; ⑥ The mass of the steel balls in the mill on the previous day M q , M q =100·Φ·(M max / (Φ max ·100)). Therefore, the ball filling rate of the semi-autogenous grinding mill is: Φ=100%·M / (M max / Φ max )=100%·(M q +M d -M x -M t ) / (M max / Φ max )=100%·(M q +M d -M x -M t ) / (168 / 15%).

[0045] In the embodiment of the present application, the steel ball filling rate Φ before the semi-autogenous grinding mill runs for a time t is obtained. q include:

[0046] The ball mill cavity of the semi-autogenous mill is spherical. If the semi-autogenous mill is in a stopped state before the running time t, the circular section 1 passing through the center of the ball and perpendicular to the ground is used as the calculation basis, and the area is recorded as S; the shaded area 2 in the circular section 1 represents the area covered by the steel ball, and the area is recorded as S1Φ q =S1 / S.

[0047] It should be noted that in the above calculation formula, the area units of the circular section 1 and the shaded area 2 must be the same, for example, the units can both be m 2 or cm at the same time 2 wait.

[0048] In the embodiments of the application, if the running duration t is 1 day, then, Φ q is the filling rate of steel balls at the end of the previous day, which can also be understood as the filling rate of steel balls when the operation of this day is about to start but has not started yet.

[0049] In the embodiments of the present application, S1 = S s - S t , where S s is the sector area corresponding to the shaded area 2 within the circular cross-section 1; S t is the area of the triangle formed by connecting the endpoints of the shaded area 2 within the circular cross-section 1 to the center of the circle.

[0050] It should be noted that in the above calculation formula, the units of the shaded area 2 and the triangle area must be the same. For example, the unit can be m 2 simultaneously or cm 2 etc.

[0051] First of all, in any case, initially the mill needs to be shut down to measure the initial filling rate of steel balls. The purpose is to know the exact mass of steel balls / filling rate of steel balls inside the mill at the beginning, because the calculation of the filling rate of steel balls on the current day requires knowing the mass of steel balls / filling rate of steel balls in the mill on the previous day, making the calculation more accurate. In addition, after the mill has been running for some time, due to changes in ore properties or mill operating conditions, there will be certain deviations. Therefore, after running for some time, for example, during monthly maintenance, the mill is shut down to re-measure the filling rate of steel balls, which plays a role in calibration.

[0052] In the embodiments of the present application, as Figure 1 shown, the calculation formula uses the chord length method for measurement, specifically as follows: First, the semi-autogenous mill is shut down to measure the spherical chord length L, then the angle θ is calculated, and the sector area and triangle area in the figure are obtained. Subtracting them gives the volume of the shaded part of the cross-section. The proportion of the volume of the shaded part in the cross-sectional circle is the filling rate of steel balls in the semi-autogenous mill. Φ = S_shadow / S_circle · 100% = (S_sector - S_triangle) / S_circle · 100% = (π · R 2 · (2θ / 360) - 1 / 2 · R 2 · sin2θ) / π · R 2 · 100%, that is, Φ = (π · (2θ / 360) - 1 / 2 · sin2θ) / π · 100%, where sinθ = L / 2 / R, then θ = arcsin(L / 2 / R), then 2θ = 2 · arcsin(L / 2 / R), L is the measured chord length, R is the radius of the semi-autogenous mill after removing the shell lining and lifting bars. The radius of the semi-autogenous mill is about 4.25 meters, the thickness of the cylinder is 0.05 meters, and the thickness of the lining / lifting bars is 0.2 meters. Therefore, R is 4 meters.

[0053] In the embodiment of the present application, the steel ball filling rate Φ before the semi-autogenous grinding mill runs for a time t is obtained. q Including: If the semi-autogenous grinding mill is in operation for the first time t, then Φ q As the Φ value to be calculated, use formula 1 to calculate Φ q size.

[0054] According to the embodiment of the present application, if the SAG mill is in operation before the running time t, for example, the entire operation cycle of the SAG mill is expected to be 1 month, if the running time t is one day (specifically, on the 26th), then the steel ball filling rate Φ before the running time t is q The running time t' can be pushed forward (specifically, on the 25th) and calculated using Formula 1 (the calculation can combine the data on the 25th and the data at the end of the 24th to obtain the steel ball filling rate at the end of the 25th, which is used as the basis for calculation on the 26th).

[0055] In the embodiments of the present application, M x =T×K, where T is the total mass of ore processed during the operating time t, and K is the mass of steel balls consumed per unit mass of ore processed. K is the mass of steel balls consumed per unit mass of ore processed, which is also the average cumulative unit consumption of a particular ore. The units of T and K must be consistent. For example, if the total mass of ore processed during the operating time t is kg, then the mass of steel balls consumed per unit mass of ore processed is kg / kg.

[0056] In the embodiments of the present application, M t =n·ρ·4 / 3·π·(d / 2)3, where n is the number of balls ejected during the running time t, and ρ is the density of the steel balls in kg / m 3 ; d is the average diameter of the spit ball, in m.

[0057] In an embodiment of the present application, during the operation of the semi-autogenous mill, the diameter of some worn steel balls becomes smaller and they are ejected through the holes of the gravel discharge grid plate of the semi-autogenous mill. The average diameter of the ejected balls is smaller than the hole diameter of the gravel discharge grid plate of the semi-autogenous mill.

[0058] In the embodiment of the present application, the preset optimal filling rate is 1-14%. When the ore hardness is relatively high, the mill needs to maintain a higher steel ball filling rate (about 6-14%), and when the ore hardness is relatively low, the mill needs to maintain a lower steel ball filling rate (1-6%).

[0059] In an embodiment of the present application, the step (1) further includes: preliminarily determining whether additional steel balls are needed based on the content of stubborn stone in the ore in the semi-autogenous mill and the sound frequency of the semi-autogenous mill.

[0060] According to the embodiments of this application, the following are specific and appropriate grinding processes that need to be adopted when processing different ores using the same semi-autogenous grinding mill. Combined with the above calculation method, the calculation formula parameters need to be adjusted during the specific implementation of process control. The following are several specific different grinding process control situations and implementation methods:

[0061] Case 1: Filling rate adjustment process during operation. The steps are as follows: When the mill current drops significantly, and the sound of the semi-autogenous mill steel balls hitting the liner is strong (proving that there is less material in the mill at this time), the amount of stubborn stones is small, it is necessary to stop adding steel balls and appropriately increase the processing capacity to ensure normal operation of the mill; when the grinding product is coarse, the mill main motor current is high, the amount of stubborn stones is large, the mill sound is muffled, that is, the sound of the steel balls hitting the liner is small, then the amount of steel balls added can be appropriately increased. That is, steel balls can be added regularly and in a fixed quantity at ordinary times, but they can also be added intermittently according to the specific conditions of the mill. Generally, this does not affect the implementation of the calculation method (that is, various situations may occur during the grinding process control. In order to ensure the safe and stable operation of the mill, adjustments must be made to the addition of steel balls to the mill, such as the frequency and amount of ball addition. These affect the process control of grinding, the filling rate of steel balls in the mill, and the unit consumption of steel balls in the mill. This method is applicable whether steel balls are added regularly or intermittently, and the calculation formula involves and takes into account the amount of balls added, the amount of balls discharged, and the amount of steel ball wear. If the number of steel balls increases or decreases suddenly, the calculation of the steel ball filling rate based on the grinding process conditions can be carried out).

[0062] Case ②: When the properties of the ore change significantly over a long period of time, such as the ore hardness decreases significantly, or the ore hardness increases significantly, the steel ball consumption in the calculation of the steel ball mass consumed on that day should be appropriately reduced or increased based on the average cumulative steel ball consumption. This does not affect the implementation of the calculation method as a whole (the implementation steps at this time require adjustments to the steel ball wear parameters in the three main factors affecting the mill's steel ball filling rate (ball addition amount, ball discharge amount, and steel ball wear amount) based on the different ore hardness. As the ore hardness increases, the steel ball consumption should be increased, and vice versa. If it is not adjusted, the corresponding calculated steel ball filling rate will be too large / too small).

[0063] Case ③: The optimal filling rate of the mill is not the same, which mainly depends on the properties of the ore: when the ore hardness is relatively high, the mill needs to maintain a higher steel ball filling rate (about 6-14%), and when the ore hardness is relatively low, the mill needs to maintain a lower steel ball filling rate (1-6%). When calculating the steel ball filling rate, it is necessary to adjust the steel ball consumption per ton of ore according to the ore. Generally, the higher the steel ball filling rate, the higher the steel ball consumption per ton, and the smaller the steel ball filling rate, the smaller the steel ball consumption per ton. The size of the steel ball filling rate in the mill does not affect the implementation of the calculation method (the specific implementation steps are, that is, when processing different ores, the optimal steel ball filling rate is different, the steel ball consumption per ton is different, and the steel ball consumption involved in the calculation formula is different, which needs to be adjusted. Specifically, it is the average cumulative consumption per ton of ore for processing the ore under the filling rate. When the steel ball filling rate increases, the steel ball consumption per ton increases, and vice versa).

[0064] Case ④: The same type of mill uses gravel removal gratings with a certain range of apertures. When the gratings of the semi-autogenous mill are replaced with different apertures, or the gravel removal gratings will cause the aperture to change due to wear, resulting in changes in the diameter of the balls, the steel ball diameter needs to be measured every day. The specific implementation of this step is that when the ore hardness is relatively high, the gravel removal grating needs to be replaced with a larger aperture to improve the crushing capacity of the steel balls in the mill; conversely, when the ore hardness is relatively low, the gravel removal grating needs to be replaced with a smaller aperture. Overall, it does not affect the implementation of this calculation method. The apertures of the gravel removal gratings are different. When the aperture changes, the diameter of the balls spit out by the mill is different, and the quality of the steel balls spit out by the mill is different. The diameter of the balls spit out in the formula needs to be updated every day to ensure that the steel ball filling rate is calculated accurately).

[0065] Case ⑤: In actual production, the semi-autogenous grinding mill needs to maintain a certain concentration when operating. When the ore is harder, the grinding concentration can be appropriately reduced to about 75%-80%. When the ore is softer, a higher grinding concentration of about 80-95% can be maintained. The size of the grinding concentration does not affect the implementation of this calculation method. Case ⑥: In actual production, if you want to change to a different type of ore, you should manually pick out the steel balls to reduce the steel ball filling rate or add steel balls to increase the filling rate before the mill is turned on. The specific implementation steps are as follows: for example, if the original ore was processed harder and the optimal filling rate of the mill is higher, when it is necessary to change to a softer ore, a large number of steel balls need to be picked out before operation to reduce the filling rate to prevent excessive steel balls from damaging the mill; when the original ore was processed softer and it is necessary to change to a harder ore, a large number of steel balls need to be added until the particle size of the grinding product meets the requirements. Before and after the ore type is changed and the mill ball filling rate is changed, the ore ball unit consumption value and the filling rate value before the mill operation need to be changed, which will not affect the implementation of this calculation method.

[0066] Example

[0067] The following examples describe the present disclosure in more detail and are intended to be illustrative only, as various modifications and variations within the scope of the present disclosure will be apparent to those skilled in the art. Unless otherwise indicated, all parts, percentages, and ratios reported in the following examples are by weight, and all reagents used in the examples are commercially available or synthesized according to conventional methods and used directly without further processing, and all instruments used in the examples are commercially available.

[0068] Example 1

[0069] For example, the Φ8500X4300mm SAG mill in a mineral processing plant has a maximum steel ball filling rate of 15%, a maximum steel ball addition capacity of 168 tons, and uses forged balls with a diameter of 120mm. The SAG mill volume is 240 cubic meters, and the mill cylinder has 32 rows of liners / lifting bars. The discharge end of the SAG mill has 32 gravel gratings with apertures of 70mm, 80mm, and 90mm, from which slurry, gravel, and smaller steel balls are discharged. See the specific actual picture for details. Figure 2 .

[0070] In 2021, the mill processed copper ore with an average cumulative oxidation rate of 40%. The average cumulative unit consumption of 120mm steel balls was about 0.36kg / ton of ore. Excluding the spitting balls, the unit consumption of steel balls was 0.23kg / ton of ore. There were 115 120mm steel balls in a barrel, and the average diameter of the semi-autogenous grinding balls was 85mm. The actual production data for February 2022 is shown in Table 1. After one month of operation, the steel ball filling rate measured at the end of the month was about 10.6%, which is basically the same as the calculated steel ball filling rate. For example, taking January 26 as an example, Φ=100%·M / (M max / Φ max )=100%·(M q +M d -M x -M t ) / (M max / Φ max )=100%·(M q +M d -M x -M t ) / (168 / 15%), where: the mass of the grinding ball M on that day q =100·Φ·(M max / (100*Φ max ))=100*8.29%·(168 / 15)=92.83t;The mass of steel balls added on the day Md=13 barrels·0.84t=10.92t;The mass of steel balls consumed on the day Md x=(15482 tons of ore*0.23kg / t) / 1000=3.56t; the mass of the balls discharged on that day M t =4 / 3·π·(0.085 / 2) 3 ·7.5·1124=2.71 tons. Then the steel ball filling rate on January 26 is Φ=100%·(M q +M d -M x -M t ) / (168 / 15%) = 100%·(92.83+10.92-3.56-2.71) / (168 / 15%) = 8.70%. The calculated steel ball filling rate on January 26 was 8.70%. The grinding ball wear consumption per unit is the average cumulative steel ball consumption per 120 balls minus the average cumulative ball discharge consumption per unit. The steel ball consumption per unit is the daily processing volume divided by the daily steel ball mass.

[0071] Table 1 Mill filling rate for copper ore with an oxidation rate of 40% in January and February 2022

[0072]

[0073]

[0074]

[0075] Example 2

[0076] The SAG mill used in this example is the same Φ8500 x 4300 mm mill as in Example 1, but it processes copper ore with an oxidation rate of approximately 75%. The average cumulative consumption of 120 mm steel balls is approximately 0.23 kg / ton of ore. Excluding the 75 mm diameter of the discharge balls, the average consumption of steel balls per ton of ore is approximately 0.17 kg / ton. The mill was shut down at the end of the month, and the measured SAG steel ball filling rate was approximately 3.63%, which is consistent with the calculated value of 3.72%. See Table 2 for details.

[0077] Table 2 Mill filling rate for copper ore with an oxidation rate of 75% in January and February 2022

[0078]

[0079]

[0080] Although the present application has been described with reference to preferred embodiments, various modifications may be made thereto and components may be replaced with equivalents without departing from the scope of the present application. In particular, the various technical features described in the various embodiments may be combined in any manner as long as there are no structural conflicts. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions within the scope of the claims.

Claims

1. A method for controlling the steel ball filling rate of a semi-autogenous grinding mill, characterized in that: The steps include: (1) Calculate the steel ball filling rate Φ after the SAG mill has been running for a period of time t according to Formula 1, Φ=100%×(M q +M d -M x -M t ) / (M max / Φ max ), Formula 1; Among them, 4h≤t≤48h; M q M is the total mass of the steel balls before running for a certain time; d M is the total mass of the steel balls added during the running time t; x M is the total mass of steel balls consumed during the running time t; t M is the total mass of steel balls ejected during the running time t; max is the maximum steel ball filling mass; Φ max is the maximum filling rate, in %; (2) Compare the calculated steel ball filling rate with the preset optimal filling rate and adjust the number of steel balls so that the steel ball filling rate is close to or equal to the preset optimal filling rate.

2. The method for controlling the steel ball filling rate according to claim 1, wherein: Get the total mass M of the steel balls before the running time t q include: Get the ball filling rate Φ before the SAG mill runs for a certain time t q ; Calculate the total mass M of the steel balls before the SAG mill starts running according to Formula 2 q , M q =100×Φ q ×[M max / (100×Φ max )], formula 2; Among them, Φ q The unit is %.

3. The method for controlling the steel ball filling rate according to claim 2, wherein: The steel ball filling rate Φ before the SAG mill runs for a certain time t is obtained q include: The ball mill cavity of the semi-autogenous mill is spherical. If the semi-autogenous mill is in a stopped state before the running time t, the circular cross section (1) passing through the center of the ball and perpendicular to the ground is used as the calculation basis, and the area is recorded as S; the shaded area (2) in the circular cross section (1) represents the area covered by the steel ball, and the area is recorded as S1, Φ q =S1 / S.

4. The method for controlling the steel ball filling rate according to claim 3, wherein: S1=S s -S t , where S s is the sector area corresponding to the shaded area (2) in the circular section (1); S t It is the area of the triangle formed by connecting the endpoints of the shaded area (2) within the circular cross section (1) and the center of the circle.

5. The method for controlling the steel ball filling rate according to claim 2, wherein: The steel ball filling rate Φ before the SAG mill runs for a certain time t is obtained q include: If the semi-autogenous grinding mill is in operation for the first time t, then Φ q The Φ value to be calculated is obtained using Formula 1.

6. The method for controlling the steel ball filling rate according to claim 1, wherein: M x =T×K, where T is the total mass of ore processed within the running time t; K is the mass of steel balls consumed in processing unit mass of ore.

7. The method for controlling the steel ball filling rate according to claim 1, wherein: M t =n·ρ·4 / 3·π·(d / 2)3, where n is the number of balls ejected during the running time t, and ρ is the density of the steel balls in kg / m 3 ; d is the average diameter of the spit ball, in m.

8. The method for controlling the steel ball filling rate according to claim 7, characterized in that: During the operation of the SAG mill, the diameter of some worn steel balls becomes smaller and they are ejected through the holes of the gravel discharge grid plate of the SAG mill. The average diameter of the ejected balls is smaller than the hole diameter of the gravel discharge grid plate of the SAG mill.

9. The method for controlling the steel ball filling rate according to claim 1, wherein: The preset optimal filling rate is 1-14%.

10. The method for controlling the steel ball filling rate according to claim 1, wherein: The step (1) also includes: Based on the content of stubborn stones in the ore in the SAG mill and the sound frequency of the SAG mill, it is preliminarily determined whether additional steel balls are needed.

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