A method for controlling overflow concentration of hydrocyclone in grinding system

Abstract

The present application discloses a method for controlling the overflow concentration of a hydrocyclone in a grinding system, comprising: obtaining a weighed amount of dry ore entering the grinding system through a belt scale; calculating the total amount of water required for the grinding system based on the overflow concentration requirement of the hydrocyclone and the weighed dry ore amount; allocating the total amount of water to each addition point in proportion, and adding water to the grinding system; obtaining a measured overflow concentration value and a flow rate value of the hydrocyclone, and calculating the calculated dry ore amount of the grinding system based on the overflow concentration measurement value and the flow rate value; comparing the overflow concentration measurement value with the overflow concentration requirement value; if the overflow concentration measurement value does not match the overflow concentration requirement value, recalculating the total amount of water added according to the calculated dry ore amount, and then proportionally allocating the water until the overflow concentration requirement value is reached. The present application calculates the total water amount based on the mass balance principle to implement control, forming a closed-loop control cycle, which can ensure efficient and stable control of the overflow concentration of the hydrocyclone.

Description

Technical Field

[0001] The present invention belongs to the technical field of cyclones, and in particular relates to a method for controlling the overflow concentration of a hydrocyclone in a grinding system. Background Art

[0002] The grinding system consists of a mill feed belt conveyor, a mill (semi-autogenous mill, ball mill), a screen (semi-autogenous drum screen or linear screen, ball mill drum screen), a slurry pump and pump sump, a classification system (hydrocyclone), and its feed water system. In a beneficiation plant's grinding system, a hydrocyclone is typically used in conjunction with a ball mill to control the fineness and concentration of the final grinding product. The overflow from the hydrocyclone is used for classification to obtain a final product that meets the required concentration. Grinding systems are primarily divided into two types, depending on the crushing process: a semi-autogenous grinding system and a conventional grinding system. Regardless of the type of grinding system, there are two main methods for controlling the cyclone overflow concentration in the actual production process: the first is the manual control method, which uses the on-site concentration pot for regular sampling and monitoring based on the production practice experience of the on-site hydrocyclone operators. When the value deviates to high or low concentration, the pump pool water replenishment valve is manually adjusted to improve the hydrocyclone classification effect to control the cyclone overflow concentration, while also taking into account the adjustment and control of the hydrocyclone overflow fineness; the second is the automatic control method, such as the control principle in the invention patent CN 111250277 B, which obtains the measurement value online in real time through the hydrocyclone overflow concentration meter, and then makes a judgment based on the pump pool liquid level. In combination with the control target, the slurry pump speed is adjusted and the hydrocyclone feed pressure is adjusted to achieve the adjustment and control of the hydrocyclone concentration, and usually also takes into account the hydrocyclone overflow fineness. The above two methods have the following disadvantages:

[0003] (1) The first method relies entirely on the operator's experience, which is difficult to control and leads to frequent system fluctuations and poor system stability;

[0004] (2) The first method is labor-intensive, especially when the ore properties change significantly. The cyclone overflow concentration fluctuates greatly. It is difficult to ensure the stability of the indicators by manual labor alone, and manual labor cannot make timely adjustments.

[0005] (3) The second method has a relatively high degree of automation and reduced labor intensity; however, the overflow concentration of the hydrocyclone is controlled by the pump pool liquid level, pump speed and hydrocyclone pressure, which has the disadvantages of large concentration fluctuations, instability and difficulty in control;

[0006] (4) The second method, when the properties of the ore fluctuate greatly, may lead to frequent system adjustments to ensure the stability and matching of the fineness and concentration of the grinding products, resulting in constant fluctuations in the concentration value and the inability to quickly reach a stable value.

[0007] (5) The first method has high labor costs and requires the operator to continuously participate in the daily management process; the second method requires frequent adjustments and large fluctuations, which will cause accelerated wear of vulnerable parts of equipment such as the cyclone sand settling port and the slurry pump impeller, thereby increasing costs;

[0008] (6) The first method has a slow and imprecise response to manual adjustment. The second method has a fast response, but it is difficult to stabilize the overflow of the hydrocyclone to a fixed value.

[0009] (7) The second method needs to be coordinated with the pump pool level control. Its control logic is complex and is affected by multiple factors such as the pump pool level, pump speed and hydrocyclone pressure. The entire hydrocyclone overflow is in a dynamic equilibrium state. The system is relatively complex and difficult to stabilize. Summary of the Invention

[0010] To solve the above problems, the present application discloses a method for controlling the overflow concentration of a hydrocyclone in a grinding system, comprising:

[0011] Step S10, obtaining the weighed dry ore amount entering the grinding system through a belt scale on the belt conveyor;

[0012] Step S20, calculating the total amount of water required for the grinding system based on the overflow concentration requirement of the hydrocyclone and the weighed dry ore amount;

[0013] Step S30, allocating the total amount of added water to each adding point in proportion, and adding water to the grinding system;

[0014] Step S40, obtaining overflow concentration measurement value and flow value of the hydrocyclone, and calculating dry ore yield of the grinding system based on the overflow concentration measurement value and flow value;

[0015] Step S50: compare the overflow concentration measurement value with the overflow concentration requirement value. If the overflow concentration measurement value does not match the overflow concentration requirement value, recalculate the total added water amount according to the calculated dry ore amount, and return to step S30 until the overflow concentration requirement value is reached.

[0016] Alternatively, calculate the total amount of water added according to the following formula:

[0017] Overflow concentration requirement = dry ore volume / (dry ore volume + total added water volume).

[0018] Optionally, in a semi-autogenous grinding process grinding system, materials are fed into a semi-autogenous mill through a belt conveyor for grinding, water is added to the semi-autogenous mill through a first adding point S1, the grinding products of the semi-autogenous mill are discharged to the semi-autogenous mill discharge screen for screening, the screen returns to the belt conveyor, and the screen flows by gravity to the hydrocyclone slag slurry pump pool, water is added to the semi-autogenous mill discharge screen and the cyclone slag slurry pump pool through a second adding point S2, the hydrocyclone slag slurry pump conveys the slurry in the cyclone slag slurry pump pool to the hydrocyclone for classification, the grit of the hydrocyclone enters the ball mill for grinding, the ground ore of the ball mill is discharged to the hydrocyclone feed pump pool, the overflow of the hydrocyclone is detected by a concentration meter and a flow meter and then goes to the screening operation, water is added to the hydrocyclone grit tank through a third adding point S3, and the total amount of water added is the sum of the amounts of water added at S1, S2 and S3.

[0019] Optionally, the water supply ratio of S1, S2 and S3 is S1:S2:S3=10:2:1.

[0020] Optionally, in a conventional grinding system, materials are fed into a ball mill through a belt conveyor for grinding, water is added to the ball mill through the fourth adding point S4, and the grinding products of the ball mill are discharged to the discharge end of the ball mill and the pump pool, water is added to the discharge end of the ball mill and the pump pool through the fifth adding point S5, the hydrocyclone feed slag slurry pump transports the slurry from the discharge end of the ball mill and the pump pool to the hydrocyclone group for classification, the sand settling of the hydrocyclone group returns to the ball mill for grinding, and the grinding is discharged to the discharge end of the ball mill and the pump pool, the overflow of the hydrocyclone is detected by the concentration meter and the flow meter and then sent to the screening operation, and the total amount of water added is the sum of the water amounts added at the fourth adding point S4 and the fifth adding point S5.

[0021] Optionally, the water supply ratio of S4 and S5 is S4:S5=1:(5~8).

[0022] Optionally, each adding point is configured as a parallel water supply pipeline, and one branch of the parallel water supply pipeline is a spare pipeline.

[0023] Optionally, the calculating of the dry ore amount of the grinding system according to the overflow concentration measurement value and the flow rate value refers to obtaining the calculated dry ore amount by multiplying the flow rate by the overflow concentration.

[0024] This application has the following technical effects:

[0025] (1) This application is highly systematic and solves the overflow concentration problem by controlling it from a macroscopic perspective and the entire system, without being subject to changes in specific operating parameters in the system. Production examples have shown that this control method is very effective and can ensure efficient and stable control of the overflow concentration of the hydrocyclone.

[0026] (2) Based on the mass balance principle and the overflow concentration control target, the total water volume is calculated and controlled, and the overflow concentration is tested, verified and fed back to form a closed-loop control loop. The total amount of added water is continuously iterated and adjusted to ultimately ensure accurate and effective control.

[0027] (3) When executing the product fineness control logic, as long as the total water volume of the grinding system remains unchanged, the overflow concentration of the hydrocyclone product can be stably controlled and unchanged, which can better be compatible with other control logics. For example: to ensure that the pump pool liquid level is within a reasonable range, it is necessary to add water to the pump pool to instantly increase the water volume. While keeping the overflow concentration of the hydrocyclone unchanged, the water volume at the S2 addition point is increased, and the water volumes at S1 and S3 will be reduced according to the adjustment rule to ensure that the total water volume remains unchanged to stabilize the overflow concentration.

[0028] (4) It can realize automatic control and greatly reduce the labor intensity of operators.

[0029] (5) Strong adaptability. Fluctuations in ore properties will cause fluctuations in product fineness. However, controlling with the total water volume logic will effectively eliminate the influence of product fineness on concentration and ensure that the overflow concentration of the cyclone is stable and controllable. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 Schematic diagram of a semi-autogenous grinding process grinding system according to an embodiment of the present invention.

[0031] Figure 2 Schematic diagram of a conventional grinding system according to an embodiment of the present invention. DETAILED DESCRIPTION

[0032] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0033] The method for controlling the overflow concentration of the hydrocyclone in the grinding system of this embodiment is based on the principle of system mass balance. The dry ore and total water entering the grinding system are equal to the dry ore and total water leaving the grinding system. Therefore, the overflow concentration of the hydrocyclone in the grinding system = dry ore / (dry ore + total water). In a semi-autogenous grinding system, the total water volume is composed of ore feed water, SAG mill discharge, pump sump water, and hydrocyclone grit feed water. In a conventional grinding system, the total water volume is composed of ore feed water, ball mill discharge, and pump sump water. This embodiment calculates the total amount of added water based on the concentration requirements of the hydrocyclone overflow (ground product) in subsequent sorting operations or processes, using the amount measured by the belt scale of the feed belt conveyor as a benchmark, and distributes it to each addition point according to a fixed ratio. The concentration is then calibrated using a concentration meter on the cyclone overflow pipe, and the dry ore content on the feed belt conveyor is calibrated using a concentration meter and flow meter. Intelligent adjustments are made based on the calibration differences to ultimately ensure that the hydrocyclone overflow concentration reaches the set target.

[0034] The method for controlling the overflow concentration of the hydrocyclone in the grinding system of this embodiment includes the following steps:

[0035] Step S10, obtaining the weighed dry ore entering the grinding system by the belt scale 2 on the belt conveyor 1, the weighed dry ore is expressed in t / h, and the water content of the weighed dry ore is usually a fixed value of 3% to 5%;

[0036] In step S20, the total amount of added water required for the grinding system is calculated based on the concentration requirement of the hydrocyclone for subsequent screening operations, that is, the overflow concentration requirement. For example, the overflow concentration requirement of the hydrocyclone in a copper mine is between 30% and 35%. In combination with the dry ore weighed by the belt scale 2 in step S10, the total amount of added water required for the grinding system is calculated.

[0037] Specifically, the total amount of added water can be calculated according to the overflow concentration requirement value = dry ore amount / (dry ore amount + total amount of added water).

[0038] Step S30: Allocate the total amount of water to be added to each adding point in proportion.

[0039] For example Figure 1 The semi-autogenous grinding system shown in the figure is Figure 1 The semi-autogenous grinding process grinding system includes a belt conveyor 1, a belt conveyor belt scale 2, a return belt conveyor 3, a semi-autogenous grinding mill 4, a semi-autogenous grinding mill discharge screen 5, a cyclone feed slag slurry pump pool 6, a cyclone feed slag slurry pump 7, a ball mill 8, a hydrocyclone group 9, and a hydrocyclone overflow concentration meter and flow meter 10.

[0040] The material in the grinding circuit is conveyed to the semi-autogenous mill 4 for grinding through the belt conveyor 1. At the same time, external water is added to the semi-autogenous mill 4 through the first adding point S1 to ensure the grinding concentration of the ore entering the semi-autogenous mill 4. The grinding products of the semi-autogenous mill 4 are discharged and screened through the semi-autogenous mill discharge screen 5. The above-screen products are directly returned to the semi-autogenous mill 4 through the return belt conveyor 3. The under-screen products flow by gravity to the hydrocyclone to feed the slag slurry pump pool 6. In order to ensure the screening efficiency and subsequent pumping needs, a second adding point S2 is set at the semi-autogenous mill discharge screen 5 and the cyclone to feed the slag slurry pump pool 6. The water supply of the second adding point S2 enters the semi-autogenous mill discharge screen 5 and the cyclone to feed the slag slurry pump pool 6. The hydrocyclone feed slurry pump 7 transfers the slurry from the hydrocyclone feed slurry pump tank 6 to the hydrocyclone 9 for classification. The grit from the hydrocyclone 9 enters the ball mill 8 for grinding. The ground ore from the ball mill 8 is discharged into the hydrocyclone feed pump tank 6. The overflow from the hydrocyclone 9 is monitored by a concentration meter and flow meter 10 before being sent to the sorting process. To control the ball mill grinding concentration, water is added to the grit trough of the hydrocyclone 9 from the third addition point S3. The total amount of water added is the sum of the water amounts from the three addition points S1, S2, and S3. For example, the water is distributed to each addition point in a ratio of approximately 10:2:1, S1:S2:S3.

[0041] Preferably, parallel water supply pipelines are provided at the first to third addition points, and one branch of the parallel water supply pipeline is a spare pipeline. When a regulating valve on one branch has a problem and needs to be repaired or replaced, the other branch can be used to work without affecting production. Figure 1 There are branches S11, S21 and S31 respectively, in which control valve groups are installed to adjust the water supply.

[0042] For example Figure 2 The conventional grinding system includes a feeding belt conveyor 1, a belt conveyor belt scale 2, a ball mill 8, a ball mill discharge end and a pump pool 4 (the discharge end is sometimes equipped with a drum screen), a cyclone feed slurry pump 7, a hydrocyclone group 9, and a hydrocyclone overflow concentration meter and flow meter 10.

[0043] The grinding circuit material is conveyed via belt conveyor 1 into the ball mill 8 for grinding. Simultaneously, external water is added to the ball mill 8 through the fourth addition point S4 to ensure the grinding concentration of the ore entering the ball mill 8. The milled ore product is discharged into the ball mill discharge terminal and pump sump 4. To ensure efficient screening at the discharge terminal and subsequent pumping needs, a fifth addition point S5 is located at the ball mill discharge terminal and pump sump 4. A hydrocyclone feed slurry pump 7 delivers slurry from the ball mill discharge terminal and pump sump 4 to the hydrocyclone group 9 for classification. The grit from the hydrocyclone group 9 is returned to the ball mill 8 for grinding. The ground ore is then discharged into the ball mill discharge terminal and pump sump 4. The hydrocyclone overflow is monitored by a hydrocyclone overflow concentration meter and flowmeter 10 before being transferred to the sorting process. The total amount of water added is the sum of the water added at the fourth and fifth addition points S4 and S5.

[0044] Preferably, the total amount of water added is distributed to each adding point according to the ratio, usually S4:S5=1:(5-8), and added.

[0045] Preferably, parallel water supply pipelines are provided at the fourth and fifth addition points, one branch of which is a spare pipeline. When a regulating valve on one branch has a problem and needs to be repaired or replaced, the other branch can be used to operate without affecting production. Figure 2 There are branches S41 and S51 respectively, in which control valve groups are installed to adjust the water supply.

[0046] In step S40, the overflow concentration measurement value and the flow rate are obtained by the hydrocyclone overflow concentration meter and the flow meter 10 respectively, and the calculated dry ore content of the grinding system is calculated based on the flow rate and the overflow concentration measurement value. Specifically, the calculated dry ore content is obtained by multiplying the flow rate by the overflow concentration measurement value.

[0047] In step S50, the overflow concentration measurement value is compared with the overflow concentration requirement value. If the overflow concentration measurement value does not match the overflow concentration requirement value, the total amount of added water is recalculated according to the calculated dry ore amount according to the overflow concentration requirement value = dry ore amount / (dry ore amount + total added water amount), and the process returns to step S30 until the overflow concentration requirement value is reached.

[0048] For example, if the measured overflow concentration of the hydrocyclone is 32%, combined with the flowmeter reading, the calculated dry ore yield of the grinding system is 390 t / h. Comparing this calculated dry ore yield with the 385 t / h dry ore yield measured by belt scale 2 clearly shows an increase in the dry ore yield of the cyclone overflow. Because the total water addition amount was previously calculated based on the dry ore yield measured by belt scale 2, which is not accurate, the total water addition amount is calculated based on the calculated dry ore yield of 390 t / h. The concentration reading is 32%, while the required overflow concentration is 30%. Since the measured overflow concentration is higher than the required overflow concentration, the total water addition amount is recalculated based on the calculated dry ore yield of 390 t / h and distributed proportionally to each addition point. Similarly, if the measured overflow concentration is lower than the required overflow concentration, the total water addition amount can be recalculated based on the calculated dry ore yield and distributed proportionally to each addition point.

[0049] It should be noted that this embodiment emphasizes system control, and the addition points are not limited to the above-mentioned 2 or 3 points, but can be more. The addition points can be appropriately selected according to the actual needs of the grinding system without affecting the overall control effect.

[0050] Taking the grinding system of a polymetallic ore dressing plant in Yunnan as an example, the grinding system adopts semi-autogenous grinding process. Figure 1 System composition. The ore processed by this project is polymetallic ore with a processing capacity of 8000t / d. The types of minerals processed include sphalerite, pyrrhotite, pyrite, magnetite, cassiterite, chalcopyrite, arsenopyrite, etc., and the ore hardness coefficient is 1 to 7. This embodiment has the remarkable characteristics of complex ore mineral composition, large fluctuation of ore hardness, and large difference in grindability. The crushing and grinding process adopts the SAB process, and the fineness of the final grinding product is -0.074mm, accounting for 69% to 71%, and the product concentration is 39% to 41%. The control method of this embodiment is used to implement total water volume control on the overflow of the hydrocyclone. By comparing the manual control operation and the automatic adjustment and operation of this embodiment, the control method of this embodiment is used. Continuous production practice proves that the qualified rate of grinding product concentration is 98.75%, and the qualified rate of grinding product concentration in manual operation mode is 94.17%. The qualified rate of grinding product concentration in the present invention is 4.58% higher than that in the manual operation mode. During the implementation of the control method of this embodiment, the hydrocyclone overflow concentration can be precisely controlled within the required range for the entire separation process (98% of the time). This significant improvement significantly reduces operator labor intensity, enabling unmanned, precise, and stable control of the hydrocyclone overflow concentration. The ability to efficiently control the hydrocyclone overflow concentration stabilizes the concentration of subsequent separation operations, significantly reducing reagent consumption during separation operations. Compared to manual control of cyclone overflow, which results in fluctuating slurry volumes, this method saves 3% to 5% in reagent consumption, resulting in more stable product grade and recovery.

[0051] Of course, the present invention may have many other embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art may make various corresponding changes and modifications based on the present invention, but these corresponding changes and modifications shall fall within the scope of protection of the claims of the present invention.

Claims

1. A method for controlling the overflow concentration of a hydrocyclone in a grinding system, characterized in that: include: Step S10, obtaining the weighed dry ore amount entering the grinding system through a belt scale on the belt conveyor; Step S20, calculating the total amount of water required for the grinding system based on the overflow concentration requirement of the hydrocyclone and the weighed dry ore amount; Step S30, allocating the total amount of added water to each adding point in proportion, and adding water to the grinding system; Step S40, obtaining overflow concentration measurement value and flow value of the hydrocyclone, and calculating dry ore yield of the grinding system based on the overflow concentration measurement value and flow value; Step S50: Compare the overflow concentration measurement value with the overflow concentration requirement value. If the overflow concentration measurement value does not match the overflow concentration requirement value, recalculate the total amount of added water according to the calculated dry ore amount, and return to step S30 until the overflow concentration requirement value is reached. The calculation of the dry ore amount of the grinding system according to the overflow concentration measurement value and the flow value refers to multiplying the flow rate by the overflow concentration to obtain the calculated dry ore amount.

2. The method for controlling overflow concentration of a hydrocyclone in a grinding system according to claim 1, characterized in that: Calculate the total amount of water added according to the following formula: Overflow concentration requirement = dry ore volume / (dry ore volume + total added water volume).

3. The method for controlling overflow concentration of a hydrocyclone in a grinding system according to claim 1, characterized in that: In the semi-autogenous grinding process, materials are fed into the semi-autogenous mill through a belt conveyor for grinding, and water is added to the semi-autogenous mill through the first addition point S1. The grinding products of the semi-autogenous mill are discharged to the semi-autogenous mill discharge screen for screening, returned to the belt conveyor on the screen, and flowed under the screen to the hydrocyclone slag slurry pump pool by gravity. Water is added to the semi-autogenous mill discharge screen and the cyclone slag slurry pump pool through the second addition point S2. The hydrocyclone slag slurry pump conveys the slurry in the cyclone slag slurry pump pool to the hydrocyclone for classification. The grit of the hydrocyclone enters the ball mill for grinding, and the ground ore of the ball mill is discharged to the hydrocyclone feed pump pool. The overflow of the hydrocyclone is detected by the concentration meter and flow meter and then goes to the screening operation. Water is added to the hydrocyclone grit tank through the third addition point S3. The total amount of water added is the sum of the water added at S1, S2 and S3.

4. The method for controlling overflow concentration of a hydrocyclone in a grinding system according to claim 3, characterized in that: The water supply ratio of S1, S2 and S3 is S1:S2:S3=10:2:

1.

5. The method for controlling overflow concentration of a hydrocyclone in a grinding system according to claim 1, characterized in that: In a conventional grinding system, materials are fed into the ball mill through a belt conveyor for grinding, water is added to the ball mill through the fourth addition point S4, and the grinding products of the ball mill are discharged to the discharge end of the ball mill and the pump pool. Water is added to the discharge end of the ball mill and the pump pool through the fifth addition point S5. The hydrocyclone feeds the slag slurry pump to transport the slurry from the discharge end of the ball mill and the pump pool to the hydrocyclone group for classification. The sand settling of the hydrocyclone group returns to the ball mill for grinding, and the ground ore is discharged to the discharge end of the ball mill and the pump pool. The overflow of the hydrocyclone is detected by the concentration meter and flow meter and then sent to the screening operation. The total amount of water added is the sum of the water added at the fourth addition point S4 and the fifth addition point S5.

6. The method for controlling overflow concentration of a hydrocyclone in a grinding system according to claim 5, characterized in that: The water supply ratio of S4 and S5 is S4:S5=1:(5~8).

7. The method for controlling overflow concentration of a hydrocyclone in a grinding system according to claim 1, characterized in that: Each adding point is set as a parallel water supply pipeline, and one branch of the parallel water supply pipeline is a spare pipeline.

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