A method and system for automatically preparing lime milk

Abstract

The present invention relates to a method and system for automatically preparing lime milk, and belongs to the field of automation of mineral processing processes. A system for automatically preparing lime milk includes a lime milk modulation device, a lime milk grinding and filtering device, a lime milk concentration measurement and control device, a lime milk conveying and storage control device, and a control system; these are sequentially connected and, under the control of the control system, automatically control the preparation of lime milk from quicklime. A method for automatically preparing lime milk includes multiple control modules working in collaboration to prepare lime milk, including: a quicklime feeding automatic control module, a lime milk preparation system equipment interlocking control module, a quicklime and water addition lime milk modulation automatic control module, a mixed medium addition and lime milk grinding and slagging automatic control module, a lime milk concentration detection and automatic control module, and a lime milk conveying and storage automatic control module. The present invention can improve the automation level of lime milk preparation and the preparation accuracy of lime milk.

Description

Technical Field

[0001] The invention relates to a method and system for automatically preparing lime milk, which is particularly suitable for automatically preparing lime milk using quicklime in a mineral processing production process, and belongs to the technical field of mineral processing process automation. Background Art

[0002] Lime is a commonly used mineral processing agent in flotation processes, widely used in both metal and non-metallic minerals. Lime's core role in flotation is to adjust the pH of the slurry and act as a depressant. Lime neutralizes acidic substances in the slurry, rendering it alkaline, thereby facilitating the adsorption and reaction of certain flotation agents. Lime also has an inhibitory effect, increasing the hydrophilicity of minerals and thereby inhibiting their flotation. In short, by rationally adding lime to the slurry, the pH value can be altered, thereby enhancing the effectiveness of flotation agents and improving flotation efficiency.

[0003] In the invention patented technology for "Weighing-Type Automatic Milk of Lime Preparation Equipment, ZL201010597424.2," the applicant innovatively provided a new method and device for automatically preparing milk of lime using lime powder, based on the lime milk production process requirements at the time. Using lime powder to prepare milk of lime was a method used in early mineral processing operations. However, due to the high production costs, high dust levels, and severe pollution associated with this method, mineral processing operations have gradually shifted to using quicklime to directly prepare milk of lime.

[0004] Currently, the preparation of lime milk by adding quicklime and water is primarily a manual process in mineral processing. While this method is simple, cost-effective, and dust-free, it also has several drawbacks, primarily: (a) manual preparation of lime milk requires multiple workers and is labor-intensive; (b) the concentration of the prepared lime milk is unstable, affecting the accuracy of subsequent lime milk addition, thereby impacting production indicators; (c) a large amount of stone carried by the quicklime remains in the lime tank, requiring manual cleaning, which is labor-intensive; (d) the prepared lime milk contains a large amount of lime particles and slag, which can easily cause valve and pipe blockages, requiring production to be stopped for manual unclogging, affecting the normal operation of flotation production; and (e) the stone and slag carried by the quicklime require storage, which not only takes up a lot of storage space but also causes certain environmental pollution. Due to these problems in the existing lime milk preparation process, the preparation and addition of lime milk have a high failure rate and poor accuracy, thus affecting the technical indicators and economic benefits of mineral processing production. Summary of the Invention

[0005] To overcome the shortcomings of existing lime milk preparation in mineral processing, the present invention provides an automatic lime milk preparation method and system, including an automatic lime milk preparation method and an automatic lime milk preparation system. The present invention has a positive effect on improving the automation level of lime milk preparation, increasing the preparation accuracy of lime milk, reducing labor and labor intensity, reducing the discharge of waste rock and slag, and reducing steel ball consumption and lime milk production costs.

[0006] According to the process characteristics of using quicklime to prepare lime milk in the current mineral processing process and the problems existing in the existing process, the present invention has made further innovations in technical methods and equipment systems on the basis of the technology for which an invention patent has been obtained (application number ZL201010597424.2, patent name "Weighing type automatic preparation equipment for lime milk").

[0007] The overall technical concept of this invention is as follows: quicklime storage, lime milk preparation, and lime output are controlled through a lime trough equipped with a spiral and elevator. The system is suitable for quicklime with large particle size and entrained stones. Lime milk is ground and deslagging to prevent lime clumping and produce lime milk of acceptable fineness. Lime milk concentration is measured and water addition is controlled to produce lime milk that meets process concentration and fineness requirements. The lime milk is then transported to a storage tank to provide sufficient lime milk for flotation production. A supporting automatic control method is proposed, forming an automatic control method and equipment system suitable for preparing lime milk from quicklime. This method is suitable not only for the automatic preparation of lime milk in mineral processing production processes, but also for other similar production processes. Entrained stones in the quicklime are used as auxiliary grinding media, which are gradually consumed during the grinding process, eliminating the need for manual cleaning of entrained stones in the quicklime and thus repurposing waste.

[0008] The technical solution of the present invention is to provide an automatic lime milk preparation system, comprising a lime milk modulation device, a lime milk grinding and filtering device, a lime milk concentration measurement and control device, a lime milk conveying and storage control device, and a control system. The lime milk modulation device, lime milk grinding and filtering device, lime milk concentration measurement and control device, and lime milk conveying and storage control device are sequentially connected and, under the control of the control system, automatically control the preparation of lime milk from quicklime.

[0009] The lime milk modulation device includes a frequency converter 2, an electric regulating valve 3, an electromagnetic flowmeter 4, a semicircular lime trough 5, a feed port 6, an array type nozzle 7, a screw 8, a screw elevator 9, a reduction motor 24, and a chute 25.

[0010] The semicircular lime trough 5 is used to store quicklime and is semi-cylindrical and installed in a sloped manner;

[0011] The screw 8 is driven by a reduction motor 24 and is used to push the lime forward and output it. It has a single spiral structure and is installed inside the semicircular lime trough 5. Its upper end is connected to the reduction motor 24 and is installed on the rotating shaft, and its lower end is connected to the screw elevator 9. The height of the screw 8 is controlled by the screw elevator 9. The reduction motor 24 is controlled by the frequency converter 2, thereby adjusting the speed of the screw 8.

[0012] The electric regulating valve 3, electromagnetic flowmeter 4, and array nozzle 7 are connected in sequence to control the flow of the spray water. The flow of the spray water is adjusted by adjusting the valve opening of the electric regulating valve 3, and the spray water flow is detected by the electromagnetic flowmeter 4. The array nozzle 7 has multiple nozzles and is installed at the lower end of the semicircular lime trough 5 to spray lime.

[0013] The chute 25 is used to transport the lime output from the semicircular lime trough 5 to the small ball mill 10 .

[0014] The technical solution of the lime milk grinding and filtering device is as follows: a lime milk grinding and filtering device, comprising a small ball mill 10, a vibrating screen 11, and a slag receiving cart 12. The lime milk is ground by the small ball mill 10 to be fully finely ground. The small ball mill 10 uses small steel balls and stones carried by quicklime as grinding media, turning discarded stones into useful ones, thereby reducing the consumption of small steel balls and avoiding the stacking of large amounts of stones. The small ball mill 10 is installed at an angle, with the outlet slightly lower than the inlet; the lime milk output by the small ball mill 10 enters the vibrating screen 11, and through the vibration, the lime milk and the slag are fully separated and the screen is prevented from being clogged. Qualified lime milk enters the concentration measuring container 14, and the slag enters the slag receiving cart 12.

[0015] The technical solution of the lime milk concentration measuring and control device is: a lime milk concentration measuring and control device, including a solenoid valve 13, a concentration measuring container 14, a force sensor 15, a concentration measuring ultrasonic level meter 16, a concentration measuring stirrer 17, and a force sensor signal transmitter 18.

[0016] The concentration measurement container 14 is used to buffer lime milk and measure and control its concentration, ensuring that the lime milk is of acceptable concentration each time it is prepared. The concentration measurement container 14 is installed below the vibrating screen 11 and receives the lime milk output from the vibrating screen 11. The solenoid valve 13 is used to control the amount of water added to control the concentration of the lime milk. A force sensor 15 measures the total weight of the concentration measurement container 14, with its signal amplified and conditioned by a force sensor signal transmitter 18. A concentration-measuring ultrasonic level meter 16 measures the lime milk level in the concentration measurement container 14. The concentration and level signals are transmitted to the control system 1 for lime milk concentration calculation and level control.

[0017] The concentration measuring stirrer 17 is used to prevent the lime milk from settling, and a plurality of blades are arranged in sections on its rotating shaft to ensure that the lime milk does not settle and the liquid surface is flat at a slow rotation speed, so as to facilitate accurate detection of the lime milk level.

[0018] The technical solution of the lime milk conveying and storage control device is as follows: it includes a pipe flexible connector adapter 19, a small slurry pump 20, a lime milk storage barrel 21, a storage barrel agitator 22, and a storage barrel ultrasonic level meter 23. The small slurry pump 20 transports lime milk from the concentration measurement container 14 to the lime milk storage barrel 21. The small slurry pump 20 is installed at a lower position than the lime milk storage barrel 21. The pipe flexible connector adapter 19 connects the output pipe of the concentration measurement container 14 and the input pipe of the small slurry pump 20 to reduce the impact of external factors on the measurement of the force sensor 15. The lime milk storage barrel 21 is installed at a relatively high position to ensure a high flow rate of lime milk during gravity flow, thereby avoiding pipe blockage. The storage barrel agitator 22 has multiple sets of blades arranged in sections on the rotating shaft, which can prevent the lime milk from settling and keep the liquid surface flat at slow speeds, thereby improving the liquid level detection accuracy of the lime milk storage barrel 21.

[0019] The technical solution of the control system is: including a touch screen computer, a programmable controller, an AC contactor, a circuit breaker, protective electrical appliances, a control cabinet, peripheral circuits, etc. The control system realizes power supply and distribution, control and management of all equipment in the lime milk preparation system.

[0020] A method for automatically preparing milk of lime, comprising:

[0021] Automatic control of quicklime feeding is performed through the quicklime feeding automatic control module;

[0022] The lime milk preparation system equipment interlocking control is carried out through the lime milk preparation system equipment interlocking control module;

[0023] Automatic control of lime milk mixing by adding quicklime and water is performed through the quicklime and water mixing lime milk automatic control module;

[0024] Automatic control of mixed medium addition and lime milk grinding and deslagging is performed through the mixed medium addition and lime milk grinding and deslagging automatic control module;

[0025] The lime milk concentration detection and automatic control module is used to detect and automatically control the lime milk concentration;

[0026] Automatic control of lime milk delivery and storage is performed through the lime milk delivery and storage automatic control module;

[0027] All the modules mentioned above work together to achieve automatic control of lime milk preparation.

[0028] The equipment interlocking control module of the lime milk preparation system comprises the following working steps:

[0029] Step S11: Upon receiving the general start command, the system will issue an audible and visual warning, and then start the relevant devices in the order from the back to the front of the process. Upon receiving the general start command of the control system, the system will first issue a ringing and flashing warning, and after a delay of several minutes, the system devices will be started in the order from the back to the front of the process.

[0030] Step S12: Upon receiving a general stop command, the system delays and stops the relevant equipment in descending order according to the process flow. General stop commands are categorized as emergency and normal. Upon receiving an emergency stop command, the system immediately stops all equipment; upon receiving a normal stop command, the system stops equipment sequentially from the beginning to the end. If the current lime milk preparation has not yet been completed, all equipment is stopped after that. If subsequent flotation production is in progress, the storage tank agitator 22 remains in operation until manually stopped.

[0031] Step S13: Start or stop the screw and screw elevator according to the feeding control instruction. After receiving the control instruction to start feeding, the system starts or stops the screw 8, screw elevator 9 and reduction motor 24 according to the system control needs.

[0032] Step S14: Start or stop the lime milk preparation device according to the lime milk preparation equipment control instruction. After receiving the lime milk preparation equipment control instruction, the system starts or stops the screw 8, the screw elevator 9 and turns on or off the spray water according to the control needs.

[0033] Step S15: Start or stop the grinding and filtering device according to the lime milk grinding and filtering device control instruction. After receiving the lime milk grinding and filtering device control instruction, the system starts or stops the small ball mill 10 and the vibrating screen 11 according to control needs.

[0034] Step S16: Start or stop the lime milk concentration measurement and control device according to the lime milk concentration measurement and control instruction. After receiving the lime milk concentration measurement and control instruction, the system starts or stops the concentration measurement stirrer 17 and the electromagnetic valve 13 according to control needs.

[0035] Step S17: Start or stop the lime milk conveying and storage control device according to the lime milk conveying and storage control instruction. After receiving the lime milk conveying and storage control instruction, the system starts or stops the small slurry pump 20 and the storage bucket agitator 22 according to control needs.

[0036] The quicklime feeding automatic control module comprises the following working steps:

[0037] Step S21: Adjusting the screw height and screw speed to the desired values. The screw lifter 9 adjusts the screw height and the screw speed to the desired value, and the frequency converter 2 adjusts the screw height and the screw speed to the desired value. These two desired values ​​are obtained by debugging the control system in advance.

[0038] Step S22: Quicklime is fed from the feed port into the semicircular lime trough, and the quicklime is transported and stacked by the spiral rotation. After the quicklime is fed from the feed port and falls into the semicircular lime trough 5, the quicklime is transported forward by the spiral rotation, thereby achieving the stacking of the quicklime in the semicircular lime trough 5.

[0039] Step S23: Controlling the thickness of the quicklime stacking by adjusting the spiral height. During the quicklime transportation process, the spiral 8 is slowly lifted by the spiral elevator 9, thereby stacking quicklime of different thicknesses so that the quicklime fills the semicircular lime trough 5.

[0040] Step S24: Determine the load of the screw based on the current value of the screw motor and adjust the height of the screw based on the load. The deeper the screw 8 is embedded in the lime, the greater the motor current of the screw 8 is, and vice versa. The height of the screw 8 is adjusted based on the motor current of the screw 8.

[0041] Step S25: Quicklime is stacked in the semicircular lime trough 5 from bottom to top until the quicklime is transported and stacked. By gradually lifting the control mode of the screw 8, the quicklime is stacked in the semicircular lime trough 5 from the lower end to the upper end of the screw 8 until the quicklime input from the feed port 6 is stacked.

[0042] The automatic control module for adding quicklime and water to prepare lime milk comprises the following working steps:

[0043] Step S31: Control the spray water flow rate to a set value and start the screw to output lime. The control loop composed of the electric regulating valve 3, electromagnetic flowmeter 4 and PID controller controls the spray water flow rate to a set value range, and the lime is output from the semicircular lime trough 5 by the rotation of the screw 8.

[0044] Step S32: The lime output flow rate is controlled by adjusting the spiral speed and height. The lime output flow rate is related to the speed and height of the spiral 8. Higher spiral speeds increase the flow rate, while lower spiral heights increase the output flow rate, and vice versa. The control system automatically adjusts the spiral speed and height based on control needs.

[0045] Step S33: Adjust the output lime and spray water flow rates based on the lime milk concentration and flow rate in the concentration measurement container and control them within upper and lower limits. When the dry lime mass flow rate and lime milk concentration exceed the upper limit, reduce the screw speed to reduce the lime output flow rate; when the dry lime mass flow rate and lime milk concentration are below the lower limit, increase the screw speed to increase the lime output flow rate; when increasing the screw speed cannot output enough dry lime, gradually reduce the screw height to increase the lime output flow rate; when the lime milk concentration is too low, automatically reduce the spray water flow rate until the lime output flow rate meets the requirement, and adjust the spray water flow rate to the normal value.

[0046] Step S34: Control the lime milk concentration in the concentration measurement container to be within a certain range above the process requirement. To facilitate subsequent control of the lime milk concentration, the lime milk concentration in the concentration measurement container 14 must first be controlled to be within a certain range above the process requirement to ensure that the lime milk concentration does not fall below the process requirement when large fluctuations occur in the process.

[0047] Step S35: When receiving the instruction to stop lime milk preparation, the lime milk preparation is stopped. When the system receives the instruction to stop lime milk preparation, the screw 8 and the screw elevator 9 are immediately stopped, and the spraying water is turned off, thereby stopping the lime milk preparation.

[0048] The automatic control module for adding the mixed medium and grinding and removing the slag of the lime milk comprises the following working steps:

[0049] Step S41: Using the current value of the small ball mill as a reference, add small steel balls from the inlet of the small ball mill until the current reaches an empirical value. The current value of the small ball mill 10 is related to its load. Since the load of the small ball mill 10 is primarily composed of small steel balls, the current value is primarily determined by the load of small steel balls. Using the current value of the small ball mill 10 as a reference, add small steel balls from the inlet of the small ball mill 10 until the current value reaches an empirical value. Due to the characteristic of the small ball mill current value and its load forming a single peak value, a gradual addition of small steel balls is used to maintain the load of the small ball mill 10 at an appropriate level before the peak value.

[0050] Step S42: The lime milk is ground using small steel balls as the primary grinding medium and rocks entrained with the lime as the secondary grinding medium. Because rocks entrained with the quicklime are random, the small steel balls are added to the small ball mill 10 to ensure that the loading level is slightly above the minimum. This results in a grinding medium state in which the small steel balls are the primary grinding medium and rocks entrained with the lime are the secondary grinding medium for grinding the lime milk.

[0051] Step S43: The amount of small steel balls to be added is calculated based on the running time of the small ball mill and the current of the small ball mill. The small steel balls are constantly worn out during the grinding process and need to be replenished regularly. The amount of small steel balls to be added within the time limit is calculated and replenished accordingly. The more small steel balls are added, the greater the current value. When the current value reaches a certain value, the addition of small steel balls is stopped.

[0052] Step S44: The load state of the small ball mill is determined and controlled based on the average current value and its changing trend over a period of time. Since the load of the small ball mill varies, a data sequence of the average current value and its changing trend over a period of time is obtained and used as a basis for determining and controlling the load state of the small ball mill. If the load state is excessive, lime milk preparation is stopped and resumed after the load state returns to normal.

[0053] Step S45: The lime milk is filtered using a vibrating screen. The product below the screen is qualified, while the product above the screen is slag. The slag slides into a slag receiving cart due to the vibration. The lime milk is filtered using a vibrating screen 11. The product below the screen is qualified, while the product above the screen is slag. The slag slides into a slag receiving cart 12 due to the vibration. The slag receiving cart 12 can be lifted to a designated location by a crane in the factory building and then manually pushed for processing.

[0054] The lime milk concentration detection and automatic control module comprises the following working steps:

[0055] Step S51: The concentration measuring stirrer stirs at a low speed to keep the lime milk suspended and the liquid surface level, facilitating accurate liquid level measurement. The concentration measuring stirrer 17 has multiple sets of blades on its stirring shaft, which can maintain the lime milk suspended and the liquid surface level during low-speed stirring, facilitating accurate liquid level measurement in the concentration measuring container 14.

[0056] Step S52: The liquid level of the concentration measurement container is detected by an ultrasonic level meter, and the gross weight of the concentration measurement container is detected by a force sensor. The liquid level of the concentration measurement container 14 is detected by an ultrasonic level meter 16 installed above the concentration measurement container 14, and the gross weight of the concentration measurement container 14 is detected by a force sensor 15 installed below the concentration measurement container 14. The gross weight is subtracted from the gross weight to obtain the weight of the milk of lime.

[0057] Step S53: Calculate the lime milk concentration in the concentration measurement container using a mathematical model. The mathematical model for calculating the lime milk concentration is:

[0058]

[0059] Where p is the percentage concentration, d0 is the density of water, δ is the density of dry lime, K v is the volume coefficient, N L0N is the A / D value of the level signal when the concentration measurement container is empty. L K is the current A / D value of the concentration measurement container's level signal. w is the weight coefficient, N w0 is the weight signal A / D value when the concentration measurement container 14 is emptied, N w It is the current weight signal A / D value of the concentration measurement container 14.

[0060] Step S54: Calculate the volume flow rate of lime milk and the mass flow rate of dry lime based on the liquid level, concentration, and density of the lime milk in the concentration measurement container. The dry lime flow rate and the volume flow rate of lime milk are calculated based on the change in the liquid level of the concentration measurement container 14 over a period of time and the current concentration. Assuming the change in the liquid level of the concentration measurement container 14 over time T is ΔL, the current concentration of lime milk is p, and the current density is d, the volume flow rate Q of lime milk output from the semicircular lime trough 5 is: v And the mass flow rate Q of lime milk converted into dry lime m The calculation formula is:

[0061] Volume flow Q v Calculation formula: Q v =K Q ΔL / T

[0062] Mass flow rate Q m Calculation formula: Q m =Q v dp

[0063] Step S55: Calculate the upper limit of the liquid level corresponding to the current lime milk concentration. When the liquid level reaches this upper limit, issue a command to stop lime milk preparation. The amount of dry lime required for one preparation of lime milk and the upper limit of the liquid level of the concentration measurement container 14 are calculated based on the lime milk process concentration and the volume of the concentration measurement container 14. When the measured liquid level reaches the upper limit, a command to stop lime milk preparation and a command to stop grinding and filtering the lime milk are issued.

[0064] Step S56: Stop lime milk preparation, and gradually control the lime milk concentration to the process requirement value through pulse control of the water addition solenoid valve, and at the same time issue a slurry pump delivery instruction. The system immediately stops lime milk preparation according to the stop lime milk preparation instruction, waits for a few minutes, and after the prepared lime milk has completely flowed into the concentration measuring container 14, the lime milk concentration is adjusted to the process requirement value by opening the solenoid valve 13 one by one. When the concentration error is less than 0.5%, stop adding water, complete the preparation of the lime milk concentration, and at the same time issue a slurry pump delivery instruction. The opening time calculation formula of the solenoid valve 13 is:

[0065]

[0066] Where, t is the opening time of the solenoid valve, ps is the lime milk concentration required by the process, p is the current lime milk concentration, Kq is the flow coefficient of the solenoid valve, K w is the weight coefficient, N w0 is the weight signal A / D value when the concentration measurement container 14 is emptied, N w It is the current weight signal A / D value of the concentration measurement container 14.

[0067] The lime milk conveying and storage automatic control module comprises the following working steps:

[0068] Step S61: Start the small slurry pump to transfer qualified lime milk to the lime milk storage tank, while simultaneously operating the storage tank agitator. Upon receiving the small slurry pump start command, the system immediately starts small slurry pump 20 to transfer lime milk to the lime milk storage tank 21 and simultaneously operates the storage tank agitator 22. If flotation production is ongoing, the storage tank agitator remains in operation.

[0069] Step S62: When the weight change of the concentration measurement container falls below a threshold for a period of time, the small slurry pump and the concentration measurement agitator are stopped. The weight of the concentration measurement container 14 decreases as the lime milk is transported. When the weight change of the concentration measurement container 14 falls below the threshold, it indicates that the lime milk in the concentration measurement container 14 has been emptied. After a delay, a command to stop lime milk concentration measurement and control is issued.

[0070] Step S63: Detecting the liquid level of the lime milk storage tank by using the storage tank ultrasonic level meter. The liquid level of the lime milk storage tank 21 is detected by using the storage tank ultrasonic level meter 23 installed above the lime milk storage tank 21.

[0071] Step S64: When the liquid level of the lime milk storage tank is higher than the upper limit, a command to stop lime milk preparation is issued. When the liquid level of the lime milk storage tank 21 is higher than the upper limit, the system issues a command to stop lime milk preparation.

[0072] Step S65: When the liquid level of the lime milk storage tank is lower than the lower limit, a lime milk preparation start instruction is issued. When the liquid level of the lime milk storage tank 21 is lower than the lower limit, the system issues a lime milk preparation start instruction.

[0073] The present invention is based on the technology of the invention patent application number ZL201010597424.2, entitled "Weighing-type Automatic Preparation Equipment for Lime Milk," and further innovates the technical method and equipment system according to the process characteristics of using quicklime to prepare lime milk in the current mineral processing process. The invention comprises the following steps: designing a device with quicklime storage, lime milk preparation and lime output functions, which is particularly suitable for the case where large pieces of quicklime and large rocks are entrained; grinding and deslagging the lime milk prevents lime agglomeration and obtains lime milk of qualified fineness; detecting the concentration of the lime milk and controlling the addition of water to obtain lime milk that meets the process concentration and fineness requirements; and transporting the lime milk to a storage tank to provide sufficient lime milk for flotation production. At the same time, in order to realize the automatic control of the designed lime milk preparation equipment system, a corresponding automatic control method is proposed, forming an automatic control method and equipment system suitable for preparing lime milk using quicklime. The method and equipment system are not only applicable to the automatic preparation of lime milk in the mineral processing production process, but also applicable to the automatic preparation of lime milk in other similar production processes. The method can realize the automatic control of the lime milk preparation process from feeding, mixing, grinding, filtering, concentration measurement, concentration control, transportation to storage. At the same time, the stones entrained in the quicklime are used as auxiliary grinding media and are gradually consumed during the grinding process, thereby eliminating the need for manual cleaning of the stones entrained in the quicklime, and turning waste into useful materials. The present invention has a positive effect on improving the automation level of lime milk preparation, improving the preparation accuracy of lime milk, reducing labor and labor intensity, reducing the discharge of waste stone and slag, and reducing steel ball consumption and lime milk production costs.

[0074] The present invention provides a method and system for automatically preparing lime milk, including the method and system for automatically preparing lime milk. The method automatically adjusts the height of a spiral to stack quicklime input from a feed port into various positions of a lime trough; controls the output flow of the output lime by adjusting the speed and height of the spiral; controls the concentration of the lime milk output from the lime trough within a required range by controlling the output flow of the output lime and the flow of spray water; outputs the lime together with stones from the lower end of the lime trough to a small ball mill through the pushing action of the spiral; and utilizes small steel balls and stones as Lime milk is ground in a small ball mill as the grinding medium to reduce steel ball consumption and prevent the release of rocks. The lime milk is filtered through a vibrating screen to remove slag and obtain lime milk of acceptable fineness. A concentration measuring container serves as a lime milk buffer and concentration and flow detection device. Water is added to adjust the slurry to maintain the required concentration within the specified range. A small slurry pump transfers the lime milk to a lime milk storage tank. The liquid level in the storage tank is monitored. When the level exceeds the upper limit, lime milk preparation is stopped. When the level falls below the lower limit, preparation is resumed. The entire lime milk preparation process is automated under the control of a control system.

[0075] The beneficial effects of the present invention are:

[0076] (1) Automatic control of the lime milk preparation process from feeding, mixing, grinding, filtering, concentration measurement, concentration control, transportation to storage has a positive effect on reducing the lime milk preparation cost, reducing labor and workers' labor intensity;

[0077] (2) By precisely controlling the grinding, slagging and concentration of lime milk, the concentration and fineness of the lime milk are ensured to be qualified and meet the process requirements, providing favorable conditions for the precise control of lime milk addition in subsequent flotation production, stabilization and optimization of mineral processing production indicators;

[0078] (3) Using stones carried by lime as auxiliary grinding media not only turns waste into useful materials, but also reduces the loss of steel balls and the discharge of waste. BRIEF DESCRIPTION OF THE DRAWINGS

[0079] Figure 1 It is the overall control flow chart of the present invention;

[0080] Figure 2 It is the system structure and control flow chart of the present invention;

[0081] Figure 3 is a side view of the lime milk preparation device of the present invention;

[0082] Figure 4 This is a flow chart of the equipment interlocking control of the lime milk preparation system of the present invention;

[0083] Figure 5 This is a quicklime feed control flow chart of the present invention;

[0084] Figure 6 This is a lime milk modulation control flow chart of the present invention;

[0085] Figure 7 This is a flow chart of the grinding, media addition and filtration control of the present invention;

[0086] Figure 8 This is a flow chart of lime milk concentration detection and control of the present invention;

[0087] Figure 9 This is a flow chart of lime milk transportation, storage and interlocking control of the present invention.

[0088] Figure 1-9The labels are: 1-control system, 2-frequency converter, 3-electric regulating valve, 4-electromagnetic flowmeter, 5-semicircular lime trough, 6-feeding port, 7-array nozzle, 8-spiral, 9-screw elevator, 10-small ball mill, 11-vibrating screen, 12-slag receiving cart, 13-solenoid valve, 14-concentration measuring container, 15-force sensor, 16-concentration measuring ultrasonic level meter, 17-concentration measuring agitator, 18-force sensor signal transmitter, 19-pipeline flexible connection adapter, 20-small slurry pump, 21-lime milk storage barrel, 22-storage barrel agitator, 23-storage barrel ultrasonic level meter, 24-reduction motor, 25-chute. DETAILED DESCRIPTION

[0089] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0090] Example 1: Figures 1-9 As shown, a mineral processing plant processes 2,000 tons of lead-zinc ore daily. The flotation process uses lime as a depressant. The lime addition requirements for flotation are: 1.2 kg of dry lime per ton of ore, a lime milk concentration of 25%, and a lime milk storage capacity sufficient to sustain flotation for 8-16 hours. Furthermore, the quicklime used to prepare the lime milk contains a high amount of stone, with a maximum particle size of 100 mm.

[0091] In order to meet the use conditions and production process requirements for lime milk proposed by flotation production, this embodiment provides a method and system for automatically preparing lime milk, including an automatic method for preparing lime milk and an automatic system for preparing lime milk.

[0092] The present embodiment provides a method and system for automatically preparing lime milk, including the method and system for automatically preparing lime milk. The invention piles quicklime input from a feed port into various positions of a lime trough by automatically adjusting the height of a screw; controls the output flow rate of the output lime by adjusting the speed and height of the screw; controls the concentration of the lime milk output from the lime trough within a required range by controlling the output flow rate of the output lime and the flow rate of the spray water; outputs the lime together with the stones from the lower end of the lime trough to a small ball mill through the pushing action of the screw; and utilizes small steel balls and stones as Lime milk is ground in a small ball mill as the grinding medium to reduce steel ball consumption and prevent the release of rocks. The lime milk is filtered through a vibrating screen to remove slag and obtain lime milk of acceptable fineness. A concentration measuring container serves as a lime milk buffer and concentration and flow detection device. Water is added to adjust the slurry to maintain the required concentration within the specified range. A small slurry pump transfers the lime milk to a lime milk storage tank. The liquid level in the storage tank is monitored. When the level exceeds the upper limit, lime milk preparation is stopped. When the level falls below the lower limit, preparation is resumed. The entire lime milk preparation process is automated under the control of a control system.

[0093] The automatic lime milk preparation system described in this embodiment includes a lime milk preparation device, a lime milk grinding and filtering device, a lime milk concentration measurement and control device, a lime milk conveying and storage control device, and a control system. The lime milk preparation device, lime milk grinding and filtering device, lime milk concentration measurement and control device, and lime milk conveying and storage control device are sequentially connected and, under the control of the control system, automatically control the preparation of lime milk from quicklime.

[0094] The technical solution of the lime milk modulation device is: a lime milk modulation device, including a frequency converter 2, an electric regulating valve 3, an electromagnetic flowmeter 4, a semicircular lime trough 5, a feed port 6, an array nozzle 7, a screw 8, a screw elevator 9, a reduction motor 24, and a chute 25.

[0095] The design and selection of various components of the lime milk preparation device of this embodiment are as follows: frequency converter 2: power 3kw, voltage 380VAC; electric regulating valve 3: caliber DN25, V-type ball valve, stainless steel material, power supply 220VAC, input signal 4-20mA; electromagnetic flowmeter 4: caliber DN25, rubber lining, stainless steel electrode, integrated, power supply 220VAC, output signal 4-20mA; semicircular lime trough 5: diameter 2000mm, length 4000mm; feed port 6: 600mm long, 800mm wide, 800mm high, inner chute slope 45°; array nozzle 7: nozzle diameter 150mm, 5 in total; spiral 8: diameter 1600mm; screw elevator 9: power 0.75KW, reduction ratio 40, stroke 1300mm; reduction motor 24: power 2.2kw, power supply 380VAC, reduction ratio 50; chute 25: 300mm wide, 200mm high, the length should be able to ensure connection with the feed port of the small ball mill 10.

[0096] In this embodiment, the semicircular lime trough 5 is used to store quicklime. It is semi-cylindrical and installed at an angle with a slope of about 10°. The spiral 8 is used to push and output quicklime. It has a single spiral structure and is installed inside the semicircular lime trough 5. Its upper end is connected to the reduction motor 24 and is installed on the rotating shaft. Its lower end is connected to the spiral elevator 9. The speed of the spiral 8 is adjusted by the frequency converter 2, and the lifting and lowering of the spiral 8 is controlled by the spiral elevator 9. The electric regulating valve 3, the electromagnetic flowmeter 4, and the array nozzle 7 are connected in sequence to control the flow rate of the spray water. The array nozzle 7 is installed at the lower end of the semicircular lime trough 5 for spraying various positions at the lower end of the semicircular lime trough 5.

[0097] The technical solution of the lime milk grinding and filtering device of this embodiment is: a lime milk grinding and filtering device, comprising a small ball mill 10, a vibrating screen 11, and a slag receiving cart 12. The lime milk is ground by the small ball mill 10 to be fully finely ground. The small ball mill 10 uses small steel balls and stones carried by quicklime as grinding media, turning discarded stones into useful ones, thereby reducing the consumption of small steel balls and avoiding the stacking of large amounts of stones. The small ball mill 10 is installed in an inclined manner, with the outlet slightly lower than the inlet; the lime milk output by the small ball mill 10 enters the vibrating screen 11, and through the vibration, the lime milk and the slag are fully separated and the screen is prevented from being clogged. Qualified lime milk enters the concentration measuring container 14, and the slag enters the slag receiving cart 12.

[0098] The design and selection of the various components of the lime milk grinding and filtering device of this embodiment are as follows: small ball mill 10: diameter * length = 900mm * 1600mm, power 7.5kw, voltage 380VAC, small steel ball diameter 30mm; vibrating screen 11: working mode is linear, screen mesh 40 mesh, power 0.75kw, voltage 380VAC, length * width = 600mm * 500mm; slag trolley 12: length * width * height = 800mm * 600mm * 600.

[0099] In this embodiment, the lime milk is ground by a small ball mill 10, which fully crushes the lime milk and provides convenience for subsequent production use. The small ball mill 10 uses small steel balls and stones carried by quicklime as grinding media, turning the previously discarded stones into useful ones. This not only reduces the consumption of small steel balls, but also reduces the large amount of stone piled up during the production process. The small ball mill 10 is installed at an angle, with the discharge port slightly lower than the feed port, at an angle of approximately 5°. The lime milk output by the small ball mill 10 enters the vibrating screen 11. The vibration can eliminate screen blockage, allowing qualified lime milk to flow out from under the screen. The slag slides from the screen into the slag receiving cart 12, which can be pushed manually or transported by the workshop starter.

[0100] The technical solution of the lime milk concentration measuring and control device is: a lime milk concentration measuring and control device, including a solenoid valve 13, a concentration measuring container 14, a force sensor 15, a concentration measuring ultrasonic level meter 16, a concentration measuring stirrer 17, and a force sensor signal transmitter 18.

[0101] The components of the lime milk concentration measurement and control device of this embodiment are designed and selected as follows: solenoid valve 13: diameter DN25, voltage 220VAC; concentration measurement container 14: diameter 800mm, height 1500mm; force sensor 15: force range 0-1000kg, output signal 0-14mV; concentration measurement ultrasonic level meter 16: measurement range 0-2000mm, power supply 220VAC, output signal 4-20mA; concentration measurement agitator 17: power 0.25kW, voltage 380VAC, speed 60r / min, blades 4 groups; force sensor signal transmitter 18: input signal 0-14mV, power supply voltage 24VDC, output signal 4-20mA.

[0102] In this embodiment, the concentration measurement container 14 is used to buffer lime milk and measure and control its concentration, ensuring that the lime milk is of acceptable concentration each time it is prepared. The concentration measurement container 14 is installed below the vibrating screen 11 and receives the lime milk output from the vibrating screen 11. The solenoid valve 13 is switched on and off to adjust the amount of water added to control the concentration of the lime milk. A force sensor 15 measures the total weight of the concentration measurement container 14, with its signal amplified and conditioned by a force sensor signal transmitter 18. A concentration-measuring ultrasonic level meter 16 measures the lime milk level in the concentration measurement container 14. The concentration and level signals are transmitted to the control system 1 for lime milk concentration calculation and level control.

[0103] The concentration measuring stirrer 17 is used to prevent the lime milk from settling, and 5 groups of blades are arranged in sections on its rotating shaft to ensure that the lime milk does not settle and the liquid surface is flat at a slow speed, so as to facilitate accurate detection of the lime milk level.

[0104] The technical solution of the lime milk conveying and storage control device described in this embodiment includes a flexible pipe adapter 19, a small slurry pump 20, a lime milk storage tank 21, a storage tank agitator 22, and a storage tank ultrasonic level meter 23. The small slurry pump 20 transports lime milk from the concentration measurement container 14 to the lime milk storage tank 21. The small slurry pump 20 is installed approximately 300 mm below the bottom of the lime milk storage tank 21. The flexible pipe adapter 19 connects the output pipe of the concentration measurement container 14 and the input pipe of the small slurry pump 20 to reduce the impact of external factors on the measurement of the force sensor 15. The lime milk storage tank 21 is installed at a relatively high position, approximately 2 meters above the concentration measurement container 14, to ensure a high flow rate during the lime milk's self-flow process, thereby preventing pipe blockage. The storage tank agitator 22 has six sets of blades arranged in sections on its rotating shaft, which can prevent the lime milk from settling and maintain a smooth liquid surface at slow speeds, thereby improving the accuracy of liquid level detection in the lime milk storage tank 21.

[0105] The components of the lime milk conveying and storage control device of this embodiment are designed and selected as follows: pipeline flexible connection adapter 19: diameter 30mm, length 150mm, silicone material; small slurry pump 20: power 1.1kW, speed 2660r / min, voltage 380VAC; lime milk storage barrel 21: diameter 1300mm, height 2200mm; storage barrel agitator 22: blades in 5 groups, speed 75r / min, power 0.75kW, voltage 380VAC; storage barrel ultrasonic level meter 23: measuring range 0-3000mm, power supply voltage 24VDC, output signal 4-20mA.

[0106] The technical solution of the control system is: including a touch screen computer, a programmable controller, an AC contactor, a circuit breaker, protective electrical appliances, a control cabinet, peripheral circuits, etc. The control system realizes power supply and distribution, control and management of all equipment in the lime milk preparation system.

[0107] The main components of the control system of this embodiment are designed and selected as follows: touch screen computer: CPU I54200, 4GB memory, 100GB hard disk, 15.6-inch capacitive touch screen; programmable controller S7-1200, 24-point DI, 24-point DO, 8-channel AI with 16-bit resolution, 4-channel AO with 12-bit resolution; AC contactors: 30A for small ball mill, 20A for spiral, 10A for other motor equipment; circuit breakers and protective devices are configured according to the control system design; control cabinet height * width * depth = 2000 * 800 * 400; peripheral circuit electrical materials and connections are configured according to the requirements of the control system.

[0108] A method for automatically preparing milk of lime, comprising:

[0109] Automatic control of quicklime feeding is performed through the quicklime feeding automatic control module;

[0110] The lime milk preparation system equipment interlocking control is carried out through the lime milk preparation system equipment interlocking control module;

[0111] Automatic control of lime milk mixing by adding quicklime and water is performed through the quicklime and water mixing lime milk automatic control module;

[0112] Automatic control of mixed medium addition and lime milk grinding and deslagging is performed through the mixed medium addition and lime milk grinding and deslagging automatic control module;

[0113] The lime milk concentration detection and automatic control module is used to detect and automatically control the lime milk concentration;

[0114] Automatic control of lime milk delivery and storage is performed through the lime milk delivery and storage automatic control module;

[0115] All the modules mentioned above work together to achieve automatic control of lime milk preparation.

[0116] The equipment interlocking control module of the lime milk preparation system comprises the following working steps:

[0117] Step S11: Upon receiving the general start command, the system activates the relevant equipment in order from the end of the process, using audio and visual notifications and a time delay. Upon receiving the general start command, the control system first sounds a bell and flashes a warning light. After a three-minute delay, the system equipment is activated in order from the end of the process to the beginning. The equipment startup sequence is: storage drum agitator 22 → concentration measurement agitator 17 → vibrating screen 11 → small ball mill 10 → screw jack 9 → screw 8.

[0118] Step S12: Upon receiving a general stop command, the system delays and stops the relevant equipment in order from the beginning to the end of the process. General stop commands are divided into emergency stop commands and normal stop commands. When an emergency stop command is received, the system immediately stops all equipment; when a normal stop command is received, the system stops equipment in order from the beginning to the end. If the current lime milk preparation has not yet been completed, all equipment is stopped after the lime milk preparation is completed. If subsequent flotation production is in progress, the storage tank agitator 22 remains in operation until manually stopped. The equipment stop sequence is: screw 8 → screw elevator 9 → small ball mill 10 → vibrating screen 11 → concentration measurement agitator 17 → storage tank agitator 22.

[0119] Step S13: Start or stop the screw and screw elevator according to the feeding control instruction. After receiving the control instruction to start feeding, the system starts or stops the screw 8, screw elevator 9 and reduction motor 24 according to the system control needs. The screw 8 is driven by the reduction motor 24.

[0120] Step S14: Start or stop the lime milk preparation device according to the lime milk preparation equipment control instruction. After receiving the lime milk preparation equipment control instruction, the system starts or stops the screw 8, the screw elevator 9 and turns on or off the spray water according to the control needs.

[0121] Step S15: Start or stop the grinding and filtering device according to the lime milk grinding and filtering device control instruction. After receiving the lime milk grinding and filtering device control instruction, the system starts or stops the small ball mill 10 and the vibrating screen 11 according to control needs.

[0122] Step S16: Start or stop the lime milk concentration measurement and control device according to the lime milk concentration measurement and control instruction. After receiving the lime milk concentration measurement and control instruction, the system starts or stops the concentration measurement stirrer 17 and the electromagnetic valve 13 according to control needs.

[0123] Step S17: Start or stop the lime milk conveying and storage control device according to the lime milk conveying and storage control instruction. After receiving the lime milk conveying and storage control instruction, the system starts or stops the small slurry pump 20 and the storage bucket agitator 22 according to control needs.

[0124] The quicklime feeding automatic control module comprises the following working steps:

[0125] Step S21: Adjust the screw height and speed to the desired values. The height of screw 8 is adjusted to the desired value by screw elevator 9, and the speed of screw 8 is adjusted to the desired value by frequency converter 2. These two desired values ​​are determined by prior debugging of the control system. In this embodiment, the height of screw 8 is adjusted to a position where its axis is parallel to the centerline of the semicircular lime trough, and the speed is adjusted to 18 rpm.

[0126] Step S22: Quicklime is fed from the feed port into the semicircular lime trough, and the quicklime is transported and stacked by the spiral rotation. After the quicklime is fed from the feed port and falls into the semicircular lime trough 5, the quicklime is transported forward by the spiral rotation, thereby achieving the stacking of the quicklime in the semicircular lime trough 5.

[0127] Step S23: Controlling the thickness of the quicklime stacking by adjusting the spiral height. During the quicklime transportation process, the spiral 8 is slowly lifted by the spiral elevator 9, thereby stacking quicklime of different thicknesses so that the quicklime fills the semicircular lime trough 5.

[0128] Step S24: Determine the load of the screw based on the current value of the screw motor and adjust the height of the screw based on the load. The deeper the screw 8 is embedded in the lime, the greater the motor current of the screw 8 is, and vice versa. The height of the screw 8 is adjusted based on the motor current of the screw 8.

[0129] Step S25: Quicklime is stacked in the semicircular lime trough 5 from bottom to top until the quicklime is transported and stacked. By gradually lifting the control mode of the screw 8, the quicklime is stacked in the semicircular lime trough 5 from the lower end to the upper end of the screw 8 until the quicklime input from the feed port 6 is stacked.

[0130] The automatic control module for adding quicklime and water to prepare lime milk comprises the following working steps:

[0131] Step S31: Control the spray water flow rate to a set value and start the screw to output lime. The control loop composed of the electric regulating valve 3, electromagnetic flowmeter 4 and PID controller controls the spray water flow rate to a set value range, and the lime is output from the semicircular lime trough 5 by the rotation of the screw 8.

[0132] Step S32: The lime output flow rate is controlled by adjusting the spiral speed and height. The lime output flow rate is related to the speed and height of the spiral 8. Higher spiral speeds increase the flow rate, while lower spiral heights increase the output flow rate, and vice versa. The control system automatically adjusts the spiral speed and height based on control needs.

[0133] Step S33: Adjust the output lime and spray water flow rates based on the lime milk concentration and flow rate in the concentration measurement container and control them within upper and lower limits. When the dry lime mass flow rate and lime milk concentration exceed the upper limit, reduce the screw speed to reduce the lime output flow rate; when the dry lime mass flow rate and lime milk concentration are below the lower limit, increase the screw speed to increase the lime output flow rate; when increasing the screw speed cannot output enough dry lime, gradually reduce the screw height to increase the lime output flow rate; when the lime milk concentration is too low, automatically reduce the spray water flow rate until the lime output flow rate meets the requirement, and adjust the spray water flow rate to the normal value.

[0134] Step S34: Control the lime milk concentration in the concentration measurement container to be within a certain range above the process requirement. To facilitate subsequent control of the lime milk concentration, the lime milk concentration in the concentration measurement container 14 must first be controlled within a certain range above the process requirement to ensure that the lime milk concentration does not fall below the process requirement during large fluctuations in the process. In this embodiment, the process requirement for lime milk concentration is 25%, and the lime milk concentration is required to be controlled at approximately 30% during the lime milk preparation process.

[0135] Step S35: When receiving the instruction to stop lime milk preparation, the lime milk preparation is stopped. When the system receives the instruction to stop lime milk preparation, the screw 8 and the screw elevator 9 are immediately stopped, and the spraying water is turned off, thereby stopping the lime milk preparation.

[0136] The automatic control module for adding the mixed medium and grinding and removing the slag of the lime milk comprises the following working steps:

[0137] Step S41: Using the current value of the small ball mill as a reference, add small steel balls from the inlet of the small ball mill until the current reaches an empirical value. The current value of the small ball mill 10 is related to its load. Since the load of the small ball mill 10 is mainly composed of small steel balls, the current value is mainly determined by the load of small steel balls. Using the current value of the small ball mill 10 as a reference, add small steel balls from the inlet of the small ball mill 10 until the current value reaches an empirical value. The empirical value of current in this embodiment is 12.6A. Due to the characteristic that the current value of the small ball mill and its load form a single peak corresponding relationship, a method of gradually adding small steel balls is adopted to maintain the load of the small ball mill 10 at an appropriate position before the peak.

[0138] Step S42: The lime milk is ground using small steel balls as the primary grinding medium, supplemented by rocks entrained with the lime. Because rocks entrained with the quicklime are random, the small steel balls are added to the small ball mill 10 to ensure that the loading level is slightly above the minimum. This results in a grinding medium state in which the small steel balls are the primary grinding medium, supplemented by rocks entrained with the lime, for grinding the lime milk.

[0139] Step S43: The amount of small steel balls to be added is calculated based on the running time of the small ball mill and the current of the small ball mill. The small steel balls are constantly worn and consumed during the grinding process, requiring regular replenishment. The amount of small steel balls to be added within the time limit is calculated and added accordingly. The more small steel balls are added, the greater the current value. When the current value reaches a certain value, the addition of small steel balls is stopped. In this embodiment, the relationship between the amount of small steel balls to be added and the running time is 0.65 kg / h, with replenishment occurring every 24 hours of operation.

[0140] Step S44: The load state of the small ball mill is determined and controlled based on the average current value and its changing trend over a period of time. Since the load of the small ball mill varies, a data sequence of the average current value and its changing trend over a period of time (e.g., 30 minutes) is obtained and used as a basis for determining and controlling the load state of the small ball mill. If the load state appears excessive, lime milk preparation is stopped and resumed after the load state returns to normal.

[0141] Step S45: The lime milk is filtered using a vibrating screen. The product below the screen is qualified, while the product above the screen is slag. The slag slides into a slag receiving cart due to the vibration. The lime milk is filtered using a vibrating screen 11. The product below the screen is qualified, while the product above the screen is slag. The slag slides into a slag receiving cart 12 due to the vibration. The slag receiving cart 12 can be lifted to a designated location by a crane in the factory building and then manually pushed for processing.

[0142] The lime milk concentration detection and automatic control module comprises the following working steps:

[0143] Step S51: The concentration measuring stirrer stirs at a low speed to keep the lime milk suspended and the liquid surface level, facilitating accurate liquid level measurement. The concentration measuring stirrer 17 has multiple sets of blades on its stirring shaft, which can maintain the lime milk suspended and the liquid surface level during low-speed stirring, facilitating accurate liquid level measurement in the concentration measuring container 14.

[0144] Step S52: The liquid level of the concentration measurement container is detected by an ultrasonic level meter, and the gross weight of the concentration measurement container is detected by a force sensor. The liquid level of the concentration measurement container 14 is detected by an ultrasonic level meter 16 installed above the concentration measurement container 14, and the gross weight of the concentration measurement container 14 is detected by a force sensor 15 installed below the concentration measurement container 14. The gross weight is subtracted from the gross weight to obtain the weight of the milk of lime.

[0145] Step S53: Calculate the lime milk concentration in the concentration measurement container using a mathematical model. The mathematical model for calculating the lime milk concentration is:

[0146]

[0147] Where p is the percentage concentration, d0 is the density of water, δ is the density of dry lime, K v is the volume coefficient, N L0 N is the A / D value of the level signal when the concentration measurement container is empty. L K is the current A / D value of the concentration measurement container's level signal. w is the weight coefficient, N w0 is the weight signal A / D value when the concentration measurement container 14 is emptied, N w It is the current weight signal A / D value of the concentration measurement container 14.

[0148] In this embodiment, d0 is the density of water, which is 1 g / cm 3 ; δ is the density of dry lime, which is 3.2 g / cm 3 , K v The volume coefficient is 1.05; N L0 K is the A / D value of the level signal when the concentration measurement container is empty, and the value is 12620; w is the weight coefficient, and its value is 0.0443.

[0149] Step S54: Calculate the volume flow rate of lime milk and the mass flow rate of dry lime based on the liquid level, concentration, and density of the lime milk in the concentration measurement container. The dry lime flow rate and the volume flow rate of lime milk are calculated based on the change in the liquid level of the concentration measurement container 14 over a period of time and the current concentration. Assuming the change in the liquid level of the concentration measurement container 14 over time T is ΔL, the current concentration of lime milk is p, and the current density is d, the volume flow rate Q of lime milk output from the semicircular lime trough 5 is: v And the mass flow rate Q of lime milk converted into dry lime m The calculation formula is:

[0150] Volume flow Q v Calculation formula: Q v =K Q ΔL / T

[0151] Mass flow rate Q m Calculation formula: Q m =Q v dp

[0152] In this embodiment, K Q It is 1.043.

[0153] Step S55: Calculate the upper limit of the liquid level corresponding to the current lime milk concentration. When the liquid level reaches this upper limit, issue a command to stop lime milk preparation. The amount of dry lime required for one preparation of lime milk and the upper limit of the liquid level of the concentration measurement container 14 are calculated based on the lime milk process concentration and the volume of the concentration measurement container 14. When the measured liquid level reaches the upper limit, a command to stop lime milk preparation and a command to stop grinding and filtering the lime milk are issued.

[0154] Step S56: Stop lime milk preparation, and gradually control the lime milk concentration to the process requirement value through pulse control of the water addition solenoid valve, and at the same time issue a slurry pump delivery instruction. The system immediately stops lime milk preparation according to the stop lime milk preparation instruction, waits for 5 minutes, and after the prepared lime milk has completely flowed into the concentration measurement container 14, the lime milk concentration is adjusted to the process requirement value by opening the solenoid valve 13 one by one. When the concentration error is less than 0.5%, stop adding water, complete the preparation of the lime milk concentration, and at the same time issue a slurry pump delivery instruction. The opening time calculation formula of the solenoid valve 13 is:

[0155]

[0156] Where, t is the opening time of the solenoid valve, p s is the lime milk concentration required by the process, p is the current lime milk concentration, Kq is the flow coefficient of the solenoid valve, K w is the weight system, N w0 is the weight signal A / D value when the concentration measurement container 14 is emptied, N w It is the current weight signal A / D value of the concentration measurement container 14.

[0157] In this embodiment, p s is 25%, Kq is 60.3, K w is 0.0443,

[0158] The lime milk conveying and storage automatic control module comprises the following working steps:

[0159] Step S61: Start the small slurry pump to transfer qualified lime milk to the lime milk storage tank, while simultaneously operating the storage tank agitator. Upon receiving the small slurry pump start command, the system immediately starts small slurry pump 20 to transfer lime milk to the lime milk storage tank 21 and simultaneously operates the storage tank agitator 22. If flotation production is ongoing, the storage tank agitator remains in operation.

[0160] Step S62: When the weight change of the concentration measurement container falls below a threshold for a period of time, the small slurry pump and the concentration measurement agitator are stopped. The weight of the concentration measurement container 14 decreases as the lime milk is transported. When the weight change of the concentration measurement container 14 falls below a threshold (0.2 kg / min in this embodiment), the lime milk in the concentration measurement container 14 has been emptied. After a delay of 3 minutes, a command to stop lime milk concentration measurement and control is issued.

[0161] Step S63: Detecting the liquid level of the lime milk storage tank by using the storage tank ultrasonic level meter. The liquid level of the lime milk storage tank 21 is detected by using the storage tank ultrasonic level meter 23 installed above the lime milk storage tank 21.

[0162] Step S64: When the liquid level of the lime milk storage tank is higher than the upper limit, a command to stop lime milk preparation is issued. When the liquid level of the lime milk storage tank 21 is higher than the upper limit, the system issues a command to stop lime milk preparation.

[0163] Step S65: When the liquid level of the lime milk storage tank is lower than the lower limit, a command to start lime milk preparation is issued. When the liquid level of the lime milk storage tank 21 is lower than the lower limit, the system issues a command to start lime milk preparation.

[0164] The specific embodiments of the present invention are described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Various changes can be made within the knowledge of ordinary technicians in this field without departing from the scope of the present invention.

Claims

1. A lime milk automatic preparation system, characterized by: The invention comprises a lime milk preparation device, a lime milk grinding and filtering device, a lime milk concentration measuring and control device, a lime milk conveying and storage control device, and a control system; the lime milk preparation device, the lime milk grinding and filtering device, the lime milk concentration measuring and control device, and the lime milk conveying and storage control device are connected in sequence, and under the control of the control system, the lime milk is automatically prepared from quicklime. The lime milk modulation device comprises a frequency converter (2), an electric regulating valve (3), an electromagnetic flowmeter (4), a semicircular lime trough (5), a feed port (6), an array type nozzle (7), a spiral (8), a spiral elevator (9), a reduction motor (24), and a chute (25); The semicircular lime trough (5) is used to store quicklime and is semi-cylindrical and installed in a sloped manner; The screw (8) is driven by a reduction motor (24) and is used to push the lime forward and output it. It has a single spiral structure and is installed inside the semicircular lime trough (5). Its upper end is connected to the reduction motor (24) and installed on the rotating shaft, and its lower end is connected to the screw elevator (9); the height of the screw (8) is controlled by the screw elevator (9); the reduction motor (24) is controlled by the frequency converter (2), thereby regulating the speed of the screw (8); The electric regulating valve (3), the electromagnetic flowmeter (4), and the array type nozzle (7) are connected in sequence to control the flow rate of the spray water. The array type nozzle (7) is provided with a plurality of nozzles and is installed at the lower end of the semicircular lime trough (5) to spray lime. The chute (25) is used to transport the lime output from the semicircular lime trough (5) to the small ball mill (10); The lime milk grinding and filtering device comprises a small ball mill (10), a vibrating screen (11), and a slag receiving cart (12); the lime milk is ground by the small ball mill (10) to be fully finely ground; the small ball mill (10) is installed in an inclined manner, with the outlet slightly lower than the inlet; the lime milk output by the small ball mill (10) enters the vibrating screen (11), and through the vibration action, the lime milk and the slag are fully separated and the screen is prevented from being blocked, and the qualified lime milk enters the concentration measuring container (14), and the slag enters the slag receiving cart (12); The lime milk concentration measuring and controlling device comprises a solenoid valve (13), a concentration measuring container (14), a force sensor (15), a concentration measuring ultrasonic level meter (16), a concentration measuring stirrer (17), and a force sensor signal transmitter (18); The concentration measuring container (14) is used to buffer lime milk and measure and control the concentration of lime milk to ensure that the concentration of lime milk prepared each time is qualified; the concentration measuring container (14) is installed below the vibrating screen (11) to receive the lime milk output by the vibrating screen (11); the amount of water added is adjusted by the switch control of the electromagnetic valve (13) to control the concentration of the lime milk; the force sensor (15) is used to measure the total weight of the concentration measuring container (14), and its signal is amplified and conditioned by the force sensor signal transmitter (18); the concentration measuring ultrasonic level meter (16) is used to measure the lime milk level in the concentration measuring container (14), and the concentration signal and liquid level signal are transmitted to the control system (1) for lime milk concentration calculation and concentration and liquid level control; the concentration measuring stirrer (17) is used to prevent lime milk from settling, and a plurality of blades are arranged in sections on its rotating shaft to ensure that the lime milk does not settle and the liquid surface is flat at a slow speed, so as to facilitate accurate detection of the lime milk level; The lime milk conveying and storage control device comprises a pipeline flexible connection adapter (19), a small slurry pump (20), a lime milk storage barrel (21), a storage barrel agitator (22), and a storage barrel ultrasonic level meter (23); lime milk is conveyed from a concentration measuring container (14) to the lime milk storage barrel (21) by the small slurry pump (20), and the installation position of the small slurry pump (20) is lower than the lime milk storage barrel (21); the pipeline flexible connection adapter (19) connects the output pipe of the concentration measuring container (14) and the input pipe of the small slurry pump (20) to reduce the influence of external factors on the measurement of the force sensor (15); the lime milk storage barrel (21) is installed at a high position so that the lime milk has a high flow rate during the gravity flow process, thereby avoiding pipeline blockage; the rotating shaft of the storage barrel agitator (22) is segmented with multiple groups of blades, which can keep the lime milk from settling and the liquid surface flat at a slow rotation speed, thereby improving the liquid level detection accuracy of the lime milk storage barrel (21); The control system includes a touch screen computer, a programmable controller, an AC contactor, a circuit breaker, protective electrical appliances, a control cabinet, and peripheral circuits; the control system is used to realize power supply, control, and management of the lime milk preparation system.

2. A method for automatically preparing milk of lime, characterized in that: The method comprises: Automatic control of quicklime feeding is performed through the quicklime feeding automatic control module; The lime milk preparation system equipment interlocking control is carried out through the lime milk preparation system equipment interlocking control module; Automatic control of lime milk mixing by adding quicklime and water is performed through the quicklime and water mixing lime milk automatic control module; Automatic control of mixed medium addition and lime milk grinding and deslagging is performed through the mixed medium addition and lime milk grinding and deslagging automatic control module; The lime milk concentration detection and automatic control module is used to detect and automatically control the lime milk concentration; Automatic control of lime milk delivery and storage is performed through the lime milk delivery and storage automatic control module; All the above modules work together to complete the automatic control of lime milk preparation; The working steps of the automatic control module for adding quicklime and water to prepare lime milk include: Step S31: The spray water flow rate is controlled within the set value, and the spiral is started to output lime; the spray water flow rate is controlled within the set value range through the control loop composed of the electric regulating valve (3), the electromagnetic flow meter (4) and the PID controller, and the lime is output from the semicircular lime trough (5) through the rotation of the spiral (8); Step S32: controlling the lime output flow rate by adjusting the spiral speed and spiral height; the lime output flow rate is related to the spiral speed and height of the spiral (8), the higher the spiral speed, the greater the flow rate, the smaller the spiral height, the greater the output flow rate, and vice versa; the control system automatically adjusts the spiral speed and spiral height according to control needs; Step S33: adjusting the output lime and spray water flow rates according to the lime milk concentration and flow rate in the concentration measuring container and controlling them within upper and lower limits; when the dry lime mass flow rate and the lime milk concentration are greater than the upper limit, reducing the screw speed to reduce the lime output flow rate; when the dry lime mass flow rate and the lime milk concentration are less than the lower limit, increasing the screw speed to increase the lime output flow rate; when increasing the screw speed cannot output enough dry lime, gradually lowering the screw height to increase the lime output flow rate; when the lime milk concentration is low, automatically reducing the spray water flow rate until the lime output flow rate meets the requirement, and at the same time adjusting the spray water flow rate to a normal value; Step S34: controlling the concentration of the lime milk in the concentration measuring container to be higher than the process requirement value within a certain range; controlling the concentration of the lime milk in the concentration measuring container (14) to be higher than the process requirement value within a certain range to ensure that the lime milk concentration does not fall below the process requirement value when there are large fluctuations in the process; Step S35: When receiving the instruction to stop lime milk modulation, the lime milk modulation is stopped; when the system receives the instruction to stop lime milk modulation, the rotation of the screw (8) and the screw elevator (9) are immediately stopped, and the spraying water is turned off, thereby stopping the lime milk modulation; The working steps of the lime milk concentration detection and automatic control module include: Step S51: The concentration measuring stirrer stirs at a low speed to keep the lime milk in a suspended state and to keep the liquid surface flat so as to facilitate accurate liquid level measurement; a plurality of blades are provided on the stirring shaft of the concentration measuring stirrer (17), which keep the lime milk in a suspended state and the liquid surface flat under the low-speed stirring state so as to facilitate accurate liquid level measurement of the concentration measuring container (14); Step S52: detecting the liquid level of the concentration measuring container by an ultrasonic level meter, and detecting the total weight of the concentration measuring container by a force sensor; detecting the liquid level of the concentration measuring container (14) by a concentration measuring ultrasonic level meter (16) installed above the concentration measuring container (14), and detecting the total weight of the concentration measuring container (14) by a force sensor (15) installed below the concentration measuring container (14); subtracting the gross weight from the total weight to obtain the weight of the lime milk; Step S53: Calculate the concentration of the lime milk in the concentration measurement container using a mathematical model; the mathematical model for calculating the concentration of the lime milk is: Where p is the percentage concentration, d0 is the density of water, δ is the density of dry lime, K v is the volume coefficient, N L0 N is the A / D value of the level signal when the concentration measurement container is empty. L K is the current level signal A / D value of the concentration measurement container, w is the weight coefficient, N w0 is the weight signal A / D value when the concentration measurement container (14) is emptied, N w is the current weight signal A / D value of the concentration measurement container (14); Step S54: Calculate the volume flow rate of lime milk and the mass flow rate of dry lime according to the liquid level, concentration and density of the lime milk in the concentration measuring container; Calculate the dry lime flow rate and the volume flow rate of lime milk according to the liquid level change of the concentration measuring container (14) over a period of time and the current concentration. Assuming that the liquid level change of the concentration measuring container (14) over a period of time T is ΔL, the current concentration of lime milk is p, and the current density is d, the volume flow rate Q of lime milk output from the semicircular lime trough (5) is v And the mass flow rate Q of lime milk converted into dry lime m The calculation formula is: Volume flow Q v Calculation formula: Q v =K Q ΔL / T; Mass flow rate Q m Calculation formula: Q m =Q v dp; Step S55: calculating the upper limit of the liquid level corresponding to the current lime milk concentration, and issuing a lime milk preparation stop instruction when the liquid level reaches the upper limit; calculating the amount of dry lime required for preparing one lime milk and the upper limit of the liquid level of the concentration measuring container (14) according to the lime milk process concentration and the volume of the concentration measuring container (14), and issuing a lime milk preparation stop instruction and a lime milk grinding and filtering stop instruction when the measured liquid level reaches the upper limit; Step S56: Stop lime milk modulation, and gradually control the lime milk concentration to the process requirement value through pulse control of the water adding electromagnetic valve, and at the same time issue a slurry pump delivery instruction; the system immediately stops lime milk modulation according to the lime milk modulation stop instruction, waits for several minutes, and after the modulated lime milk completely flows into the concentration measuring container (14), the lime milk concentration is modulated to the process requirement value by opening the electromagnetic valve (13) one by one. When the concentration error is less than 0.5%, stop adding water, complete the preparation of lime milk concentration, and at the same time issue a slurry pump delivery instruction; The calculation formula for the opening time of the solenoid valve (13) is: Where, t is the opening time of the solenoid valve, p s is the lime milk concentration required by the process, p is the current lime milk concentration, Kq is the flow coefficient of the solenoid valve, K w is the weight coefficient, N w0 is the weight signal A / D value when the concentration measurement container 14 is emptied, N w It is the current weight signal A / D value of the concentration measurement container 14.

3. The automatic preparation method of milk of lime according to claim 2, wherein: The working steps of the equipment interlocking control module of the lime milk preparation system include: Step S11: Upon receiving the general start command, the system will issue an audible and visual reminder, and then start the relevant equipment in the order from the back to the front of the process after a delay; upon receiving the general start command of the control system, the system will first issue a ringing and flashing warning, and after a delay of several minutes, the system equipment will be started in the order from the back to the front of the process; Step S12: upon receiving a general stop instruction, the system stops the relevant equipment in a delayed manner from the front to the back of the process. The general stop instruction is divided into an emergency stop instruction and a normal stop instruction. When an emergency stop instruction is received, the system stops all equipment immediately. When a normal stop instruction is received, the system stops the equipment in a sequential order from the front to the back. If the preparation of the lime milk has not been completed, all equipment will be stopped after the preparation of the lime milk is completed. If subsequent flotation production is in progress, the storage bucket agitator (22) will remain in operation until it is manually stopped. Step S13: starting or stopping the screw (8) and the screw elevator (9) according to the feeding control instruction; after the system receives the control instruction to start feeding, it starts or stops the screw (8), the screw elevator (9) and the reduction motor (24) according to the system control needs; Step S14: starting or stopping the lime milk preparation device according to the lime milk preparation equipment control instruction; after receiving the lime milk preparation equipment control instruction, the system starts or stops the screw (8), the screw elevator (9) and opens or closes the spray water according to the control needs; Step S15: starting or stopping the grinding and filtering device according to the control instruction of the lime milk grinding and filtering device; after receiving the control instruction of the lime milk grinding and filtering device, the system starts or stops the small ball mill (10) and the vibrating screen (11) according to the control requirements; Step S16: starting or stopping the lime milk concentration measurement and control device according to the lime milk concentration measurement and control instruction; after receiving the lime milk concentration measurement and control instruction, the system starts or stops the concentration measurement stirrer (17) and the solenoid valve (13) according to the control requirements; Step S17: starting or stopping the lime milk conveying and storage control device according to the lime milk conveying and storage control instruction; after receiving the lime milk conveying and storage control instruction, the system starts or stops the small slurry pump (20) and the storage barrel agitator (22) according to control needs.

4. The automatic preparation method of milk of lime according to claim 2, wherein: The working steps of the quicklime feeding automatic control module include: Step S21: adjusting the screw height and the screw speed to desired values; adjusting the height of the screw (8) to the desired value by the screw elevator (9), and adjusting the speed of the screw (8) to the desired value by the frequency converter (2), wherein these two desired values ​​are obtained by debugging the control system in advance; Step S22: quicklime is fed from the feed port (6) into the semicircular lime trough (5), and the quicklime is transported and stacked by spiral rotation; after the quicklime is fed from the feed port (6) and falls into the semicircular lime trough (5), the quicklime is transported forward by spiral rotation, thereby achieving the stacking of the quicklime in the semicircular lime trough (5); Step S23: controlling the thickness of the quicklime stack by adjusting the height of the spiral; during the quicklime transportation process, slowly lifting the spiral (8) by the spiral elevator (9), thereby achieving quicklime stacking of different thicknesses, so that the quicklime fills the semicircular lime trough (5); Step S24: judging the load of the spiral according to the current value of the spiral motor, and adjusting the height of the spiral (8) according to the load; the deeper the spiral (8) is embedded in the lime, the greater the motor current of the spiral (8), and vice versa, and the height of the spiral (8) is adjusted based on the motor current of the spiral (8); Step S25: The quicklime is stacked in the semicircular lime trough from bottom to top until the transportation and stacking are completed; by gradually lifting the control mode of the screw (8), the quicklime is stacked in the semicircular lime trough (5) from the lower end to the upper end of the screw (8) until the quicklime input from the feed port (6) is stacked.

5. The automatic preparation method of milk of lime according to claim 2, wherein: The working steps of the automatic control module for adding mixed medium and grinding and removing slag of lime milk include: Step S41: using the current value of the small ball mill (10) as a reference, adding small steel balls from the inlet of the small ball mill until the current reaches an empirical value; based on the characteristic that the current value of the small ball mill and its load form a single peak value corresponding relationship, gradually adding small steel balls is adopted to keep the load of the small ball mill (10) at an appropriate position before the peak value; Step S42: grinding the lime milk with small steel balls as the main grinding medium and stones carried by lime as the auxiliary grinding medium; when adding small steel balls to the small ball mill (10), the loading amount of small steel balls is ensured to be higher than the minimum position, so as to form a grinding medium state in which small steel balls are mainly used and stones carried by lime are used as the auxiliary grinding medium, and the lime milk is ground; Step S43: Calculating the amount of small steel balls to be added based on the running time of the small ball mill and referring to the current of the small ball mill to add small steel balls; stopping the addition of small steel balls when the current reaches a certain value; Step S44: judging and controlling the load state of the small ball mill based on the average current value and its changing trend over a period of time; obtaining a data sequence of the average current value and its changing trend over a period of time, and using this data sequence as a basis for judging and controlling the load state of the ball mill; stopping lime milk preparation when the load state becomes too large, and resuming lime milk preparation after the load state returns to normal; Step S45: The lime milk is filtered by a vibrating screen, the lime milk below the screen is qualified, the slag above the screen is slag, and the slag slides into the slag receiving cart due to the vibration; the lime milk is filtered by a vibrating screen (11), the lime milk below the screen is qualified, the slag above the screen is slag, and the slag slides into the slag receiving cart (12) due to the vibration, and the slag receiving cart (12) is lifted to a designated location by a crane in the factory building and then manually pushed open for processing.

6. The automatic preparation method of milk of lime according to claim 2, characterized in that: The working steps of the lime milk conveying and storage automatic control module include: Step S61: Start the small slurry pump to transport the qualified lime milk to the lime milk storage barrel, and run the storage barrel agitator at the same time; after receiving the instruction to start the small slurry pump, the system immediately starts the small slurry pump (20) to transport the lime milk to the lime milk storage barrel (21), and runs the storage barrel agitator (22); Step S62: When the weight change of the concentration measuring container is less than the threshold value for a period of time, the operation of the small slurry pump and the concentration measuring agitator is stopped; the weight of the concentration measuring container (14) decreases continuously with the transportation of the lime milk. When the weight change of the concentration measuring container (14) is less than the threshold value, it indicates that the lime milk in the concentration measuring container (14) has been emptied, and after a delay of a period of time, an instruction to stop the lime milk concentration measurement and control is issued; Step S63: detecting the liquid level of the lime milk storage barrel by means of a storage barrel ultrasonic level meter; detecting the liquid level of the lime milk storage barrel (21) by means of a storage barrel ultrasonic level meter (23) installed above the lime milk storage barrel (21); Step S64: When the liquid level of the lime milk storage tank is higher than the upper limit, an instruction to stop lime milk preparation is issued; When the liquid level of the lime milk storage tank (21) is higher than the upper limit, the system issues an instruction to stop lime milk preparation; Step S65: When the liquid level of the lime milk storage tank is lower than the lower limit, an instruction to start lime milk preparation is issued; when the liquid level of the lime milk storage tank (21) is lower than the lower limit, the system issues an instruction to start lime milk preparation.

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