Medium-fine crusher and circular vibrating screen load balancing closed-loop control method and system

Abstract

The present application relates to the technical field of mineral crushing and screening, and particularly relates to a medium-fine crusher and circular vibrating screen load balancing closed-loop control method and system. The present application calculates the return material ratio and the instantaneous flow of qualified material under the screen by aligning the screening and return material conveying hysteresis through the two-way online weighing of the circular vibrating screen feeding belt and the screen material return belt, and sends the return material ratio into the ore discharge port constraint ring and the material level change and measurement effective flag into the fine crusher stock bin level ring, so that the control quantity reflects the total amount entering the circular vibrating screen and the circulating amount returning to the fine crusher, thereby being able to stably identify the rising and falling trend of the closed-circuit circulating load, reduce the situation of accumulated return material caused by only increasing the mine according to the single machine load of the crusher, and thereby alleviate the problems of reduced screening efficiency when the circular vibrating screen feeding is too large and the continuous rise of the fine crusher stock bin level.

Description

Technical Field

[0001] This invention belongs to the field of mineral crushing and screening technology, specifically relating to a closed-loop control method and system for load balancing of a medium and fine crusher and a circular vibrating screen. Background Technology

[0002] The ore crushing production line can adopt a three-stage crushing process: coarse crushing, medium crushing, and fine crushing. A circular vibrating screen and a fine crusher form a closed loop: the discharge from the medium and fine crushers enters the circular vibrating screen via a feed belt; the oversize material is returned to the fine crusher's hopper via an oversize return belt; and the undersize material is output as qualified material. In this closed loop, the actual screening state of the circular vibrating screen varies with the feed rate and the particle size of the material entering the screen, and the oversize return material will consume the subsequent processing capacity of the fine crusher.

[0003] If the operation control only aims to bring the intermediate and fine crushers close to their rated loads without incorporating changes in the screening efficiency of the circular vibrating screen, an increase in the feed rate to the circular vibrating screen may lead to an increase in oversize material return. When the returned material enters the fine crusher hopper along with the incoming material from the intermediate crusher, the material level in the fine crusher hopper may continue to rise; if the feed rate to the fine crusher is too fast or the material becomes too hard, the material level or power in the crushing chamber of the fine crusher may even approach the allowable limit. Conversely, excessively reducing the upstream feed rate will cause the crushing equipment to deviate from its suitable load range.

[0004] To address the aforementioned problems, this invention proposes a closed-loop control method and system for load balancing of a medium-fine crusher and a circular vibrating screen. Summary of the Invention

[0005] To address the aforementioned problems in the prior art, the present invention aims to provide a closed-loop control method and system for load balancing of a medium and fine crusher and a circular vibrating screen.

[0006] To achieve the above-mentioned objectives, the technical solution adopted by this invention is as follows: A closed-loop control method for load balancing of a medium-fine crusher and a circular vibrating screen includes: Obtain process measurement values ​​and equipment boundaries for the same control cycle to form a process status record; calculate the return ratio and instantaneous flow rate of qualified material under the screen based on the pre-screen flow rate and return flow rate to form the screening status; The feed belt speed command for the fine crusher is generated based on the deviation between the material level in the fine crusher hopper and the target material level, and a material level stability indicator is formed; the discharge port of the fine crusher is adjusted according to the return ratio and the fine crusher load, and a discharge port command is formed within the mechanical range and the upper limit of the return constraint. The downstream capacity alarm is generated based on the actual location of the fine crusher discharge outlet, unconstrained demand, and the current allowable upper limit, and the intermediate crusher is adjusted accordingly; the load balance status is determined based on the coordination status, screening status, material level stability indicator, and the current load of the intermediate crusher.

[0007] Preferably, process measurement values ​​and equipment boundaries for the same control cycle are acquired to form a process status record, including: Receive the original value of the pre-screen flow rate, the original value of the return flow rate, the material level in the fine crusher's hopper, the load detection value of the fine crusher, the current feed rate of the intermediate crusher, the actual position of the fine crusher's discharge port, and the actual position of the intermediate crusher's discharge port; Check the timestamp, range, and actuator feedback of each measurement value. Measurement values ​​that meet the valid conditions are processed by first-order filtering. When a measurement fails, retain the previous valid setpoint and pause the ore feed increment until a preset number of valid samples are obtained continuously. The number of cycles corresponding to the lag between screening and return material conveying is determined based on the belt length and speed. The pre-screen flow filtering sequence is moved according to the number of cycles so that the pre-screen flow and return material flow being compared correspond to the same batch of material. The current load of the intermediate crusher is determined by the ratio of the current feed rate to the rated feed rate.

[0008] Preferably, the return ratio and the instantaneous flow rate of qualified material under the screen are calculated based on the pre-screen flow rate and the return flow rate to form a screening state, including: The larger of the aligned in-screen flow rate and the preset minimum effective in-screen flow rate is used as the denominator, and the return flow rate is used as the numerator to calculate the return ratio. The difference between the pre-screen flow rate and the return flow rate is taken as the instantaneous flow rate of the qualified material under the screen. The change in material level is calculated by the difference between the current material level in the silo and the material level in the silo before the preset cycle, and the direction of the change in material level is determined by the sign of the change in material level.

[0009] Preferably, the feed belt speed command for the fine crusher is generated based on the deviation between the material level in the fine crusher's hopper and the target material level, and a material level stability indicator is formed, including: The difference between the current material level in the silo and the target material level is taken as the material level deviation. Proportional, integral and differential calculations are performed on the material level deviation to obtain the unlimited speed requirement of the feed belt of the fine crusher. The unlimited speed demand is limited according to the minimum speed, maximum speed and rate of change of the feed speed actuator to form a speed command; When the fine crusher load limit status of the previous control cycle indicates that the fine crusher is already in the upper limit range, the speed command is maintained or limited to decrease. When the material level in the silo is stable within the target zone and the absolute value of the material level change is not greater than the preset stability threshold and continues for a preset evaluation time, a material level stability indicator is formed.

[0010] Preferably, the discharge port of the fine crusher is adjusted according to the return material ratio and the fine crusher load, forming a discharge port instruction within the mechanical range and the upper limit of the return material constraint, including: The load detection value of the fine crusher is normalized into a load feedback value and compared with the target value of the fine crusher load. Based on the load deviation, the unconstrained demand of the fine crusher discharge outlet is generated. The upper limit of the return material constraint is determined based on the return material ratio calibration relationship, and then the smaller value is taken from the mechanical upper limit to form the current allowable upper limit; the return material ratio calibration relationship is obtained through calibration tests, and the upper limit of the discharge port does not increase when the return material ratio increases; The unconstrained demand limit is set between the lower limit of the machinery and the current upper limit, forming a discharge port instruction; Based on the discharge port instruction, unconstrained demand, current allowable upper limit, and actual location of the fine crusher discharge port, a fine crusher load limit state is formed for use in the next control cycle.

[0011] Preferably, a downstream capacity alarm is generated based on the actual location of the fine crusher's discharge outlet, unconstrained demand, and the current allowable upper limit, and the intermediate crusher is adjusted accordingly, including: If the difference between the actual location of the fine crusher discharge outlet and the current allowable upper limit is not greater than the location tolerance, and the unconstrained demand is still greater than the current allowable upper limit plus the demand hysteresis, and the preset alarm holding time is maintained continuously, then the alarm status will be set to valid; when the unconstrained demand falls back to below the allowable upper limit minus the release hysteresis and is maintained for the release time, the alarm status will be released. When the alarm is cleared, the material level stability indicator is valid, the fine crusher load has not exceeded the limit, and the current load of the intermediate crusher is less than the rated load, the feed rate of the intermediate crusher is increased according to the preset step size, and a stable waiting period is entered after each increase. When the current load of the intermediate crusher is less than the rated load and the alarm status is valid, the current feed rate of the intermediate crusher is maintained, and a small feed instruction is sent to the actuator at the discharge port of the intermediate crusher.

[0012] This invention also provides a load-balanced closed-loop control system for a medium-fine crusher and a circular vibrating screen, comprising: The acquisition unit is used to acquire process measurement values ​​and equipment boundaries in the same control cycle to form a process status record; The flow calculation unit is used to calculate the return ratio and the instantaneous flow of qualified material under the screen based on the pre-screen flow and return flow, thus forming the screening state; The fine crusher material level control unit is used to generate a fine crusher feed belt speed command based on the deviation between the material level in the fine crusher hopper and the target material level, and to form a material level stability indicator. The fine crushing load control unit is used to adjust the fine crusher discharge port according to the return ratio and fine crushing load, and generate discharge port commands within the mechanical range and the upper limit of the return constraint. The intermediate crusher adjustment unit is used to generate downstream capacity alarms based on the actual location of the fine crusher discharge outlet, unconstrained demand, and the current allowable upper limit, and adjust the intermediate crusher accordingly. The status determination unit is used to determine the load balance status based on the coordination status, screening status, material level stability indicator, and the current load of the intermediate crusher.

[0013] Preferably, the acquisition unit checks the timestamp, range, and actuator feedback of each measurement value. Measurement values ​​that meet the valid conditions are processed by first-order filtering. The number of cycles corresponding to the lag between screening and return material conveying is determined according to the belt length and speed. The pre-screen flow filtering sequence is moved according to the number of cycles so that the pre-screen flow and return material flow being compared correspond to the same batch of material. The current load of the intermediate crusher is formed by the ratio of the current feed rate to the rated feed rate. When the measurement fails, the previous valid setpoint is maintained and the feed increment is paused until a preset number of valid samples are continuously obtained.

[0014] Preferably, the fine crushing load control unit normalizes the fine crushing load detection value into a load feedback value and compares it with the fine crushing load target value. Based on the load deviation, it generates the unconstrained demand for the fine crushing discharge outlet. Based on the return material ratio calibration relationship, it determines the upper limit of the return material constraint and then takes the smaller value with the mechanical upper limit to form the current allowable upper limit. It generates a discharge outlet instruction by limiting the unconstrained demand between the mechanical lower limit and the current allowable upper limit. Based on the discharge outlet instruction, the unconstrained demand, the current allowable upper limit, and the actual position of the fine crushing discharge outlet, it forms the fine crushing load limit state for use in the next control cycle. The fine crusher level control unit uses the difference between the current material level in the hopper and the target material level as the material level deviation. It performs proportional, integral, and derivative calculations on the material level deviation to obtain the unlimited speed requirement of the fine crusher feed belt. It limits the unlimited speed requirement to form a speed command according to the minimum speed, maximum speed, and rate of change limit of the feed speed actuator. When the fine crusher load limit status of the previous control cycle indicates that the fine crusher is already in the upper limit neighborhood, the speed command is maintained or limited to decrease.

[0015] Preferably, the intermediate crusher adjustment unit sets the alarm status to valid when the difference between the actual position of the fine crusher discharge port and the current allowable upper limit is not greater than the position tolerance, and the unconstrained demand is still greater than the current allowable upper limit plus the demand hysteresis, and the preset alarm holding time is maintained continuously. When the unconstrained demand falls back to the allowable upper limit minus the release hysteresis and is maintained for the release time, the alarm status is released. When the alarm status is released, the material level stability indicator is valid, the fine crusher load has not exceeded the limit, and the current load of the intermediate crusher is less than the rated load, the feed rate of the intermediate crusher is increased by a preset step size. When the current load of the intermediate crusher is less than the rated load and the alarm status is valid, the current feed rate of the intermediate crusher is maintained and an instruction to reduce the discharge port of the intermediate crusher is output.

[0016] Beneficial effects 1. This invention uses two online weighing systems: the feeding belt of the circular vibrating screen and the return belt of the oversize material. After the lag alignment of screening and return material conveying, the return material ratio and the instantaneous flow rate of qualified undersize material are calculated. The return material ratio is sent to the discharge port constraint ring, and the material level change and measurement validity mark are sent to the material level ring of the fine crusher hopper. This allows the control quantity to reflect the total amount entering the circular vibrating screen and the circulation volume returning to the fine crusher. This enables stable identification of the rising and falling trends of the closed-loop circulating load, reducing the accumulation of return material caused by increasing the feed only according to the single crusher load. This alleviates the problem of reduced screening efficiency and continuous rise of the material level in the fine crusher hopper when the circular vibrating screen feed is too large.

[0017] 2. This invention uses the outer ring of the fine crusher hopper to adjust the speed of the feed belt, and the inner ring of the fine crusher crushing chamber to adjust the discharge port. At the same time, it uses the return ratio calibration relationship to limit the upper limit of the discharge port. When the actual discharge port reaches the upper limit and the inner ring still gives the demand for expansion, the downstream capacity alarm is formed by maintaining time and hysteresis. In this way, while releasing the processing capacity of the fine crusher, the influence of the discharge particle size on the return of the circular vibrating screen is kept within the allowable range, and a clear and stable control signal is formed for the overload state. This reduces the increase in return and control oscillation caused by the unconstrained expansion of the discharge port.

[0018] 3. Based on downstream capacity alarms, the stable material level in the fine crusher's hopper, and the current load of the intermediate crusher, this invention coordinates the execution of increasing the feed rate, maintaining the feed rate, and reducing the discharge outlet of the intermediate crusher. After each action, it waits for the material conveying and screening status to stabilize before entering the next control cycle. This allows the output particle size and feed rate of the intermediate crusher to be adjusted online according to the capacity of the fine crusher and screening closed circuit. When changes in ore hardness cause changes in power, material level, and return material status, it maintains continuous matching of the load of the intermediate and fine crushers, thereby reducing load imbalance caused by manual observation and delayed adjustment, and improving the sustainable processing capacity of the production line. Attached Figure Description

[0019] Figure 1 This is a flowchart of the method of the present invention; Figure 2 This is a system module diagram of the present invention. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are merely for explaining the invention and are not intended to limit the scope of protection of the invention.

[0021] Example 1 The discharge from the intermediate crusher and the fine crusher merge and are then fed into the circular vibrating screen via the feeding belt. The oversize material from the circular vibrating screen returns to the fine crusher's hopper via the oversize return belt, while the undersize qualified material is output via the undersize belt. The fine crusher hopper is equipped with a level gauge, the circular vibrating screen feeding belt has a first belt scale, the oversize return belt has a second belt scale, and the fine crusher is equipped with a fine crushing load detector (which can be a crushing chamber level gauge or a power detector). The co-controller receives signals from each measuring element and outputs control commands to the feeding speed actuator of the fine crusher's feeding belt, the fine crusher's discharge actuator, the intermediate crusher's feeding device's intermediate crushing feeding actuator, and the intermediate crusher's discharge actuator, respectively.

[0022] Based on the above structure, the collaborative controller synchronously performs sampling, calculation, adjustment, and state updates according to a preset control cycle, forming a load-balanced closed-loop control method. To ensure that the quantities in each control cycle have the same time base, when the conveying delay is long, a stabilization waiting period no shorter than the time required for the material to travel from the intermediate crusher to the vibrating screen and back to the fine crusher hopper is set between the incremental feeding actions. Please refer to [link / reference]. Figure 1 As shown, this embodiment provides a closed-loop control method for load balancing of a medium and fine crusher and a circular vibrating screen. The method includes the following steps: S1. Obtain process measurement values ​​and equipment boundaries for the same control cycle to form a process status record; The collaborative controller receives the raw value of the pre-screen flow rate output by the first belt scale, the raw value of the return flow rate output by the second belt scale, the material level in the fine crusher hopper output by the level gauge, the material level or power in the crushing chamber output by the fine crusher load detector, the current feed rate of the medium crusher fed by the medium crusher feed actuator, the actual position of the fine crusher discharge outlet output by the fine crusher discharge outlet actuator, the actual position of the medium crusher discharge outlet output by the medium crusher discharge outlet actuator, and the ready status of each actuator.

[0023] The controller first checks the timestamps, flow ranges, and actuator feedback of the two belt scales; the measured values ​​that meet the valid conditions are filtered using first-order filtering.

[0024] During calibration, the number of cycles corresponding to the lag between screening and return material conveying is determined based on the belt length and speed. During operation, the pre-screen flow filtering sequence is moved according to this number of cycles to ensure that the compared pre-screen flow and return material flow correspond to the same batch of material. When the operating condition reaches steady state, the average value can also be taken within a steady-state window not shorter than the stated lag. The filtering relationship is as follows:

[0025] in, Indicates the first Any original measurement value obtained in each control cycle, Indicates the corresponding filter value. This represents the filter value from the previous control cycle. This represents dimensionless filter coefficients with values ​​greater than 0 and less than or equal to 1. This indicates the control cycle number. The controller also uses the current feed rate from the crusher. With rated feed rate The ratio forms the current load of the crusher. ; and Same units This is a dimensionless quantity. When measurement fails, the controller retains the previous valid setpoint and pauses the feed increment until a preset number of valid samples are continuously obtained. The data acquisition stage outputs a process status record with the same material batch identifier, control cycle number, and valid flag, and sends the current load of the intermediate crusher to the subsequent intermediate crusher coordination adjustment and equilibrium status determination stages. The screening status calculation stage uses two flow paths aligned with hysteresis to calculate the screening status, thereby reducing the possibility of conveying fluctuations being mistaken for changes in the return ratio.

[0026] S2. Calculate the return ratio and the instantaneous flow rate of qualified material under the screen based on the pre-screen flow rate and the return flow rate to form the screening state; Let the filtering flow rate of the first belt scale be... The filter flow rate of the second belt scale is If the units are the same, then the first... Return ratio per control cycle Instantaneous flow rate of qualified material under screening They are respectively:

[0027]

[0028] in, Indicates the relationship with the first Each return material flow sample corresponds to the pre-screen flow rate after alignment of the No. 3 conveyor belt with the same batch of material. This indicates the return flow rate of belt #4. This represents the instantaneous flow rate of qualified undersize material obtained from the material balance between the two and carried by the No. 5 conveyor belt; the unit can be tons per hour. This indicates the minimum effective pre-screening flow rate to avoid divisor distortion during low flow periods, and the unit is the same as the aforementioned flow rate. It is a dimensionless quantity; This indicates taking the maximum value among the values ​​within the parentheses.

[0029] Furthermore, the minimum effective pre-screening flow rate The capacity can be set to 20t / h. The controller also calculates the level change based on the difference between the current silo level and the silo level several cycles ago, and determines the direction of the level change based on its sign. The screening status calculation stage outputs the return ratio, the instantaneous flow rate of the qualified undersize material, the level change and its direction, and the measurement validity indicator; the silo level control stage reads the level change, the direction of change, and the validity indicator to determine whether the level loop should be updated; the discharge outlet constraint control stage reads the return ratio to determine the upper limit of the fine crusher discharge outlet; and the equilibrium state determination stage reads the return ratio and the instantaneous flow rate of the qualified undersize material to determine the equilibrium state. Thus, each output has a clear subsequent use and avoids directly incorporating the screening and conveying lag into the return ratio change during the dynamic stage.

[0030] S3. Generate the feed belt speed command for the fine crusher based on the deviation between the material level in the fine crusher hopper and the target material level, and form a material level stability indicator; The collaborative controller reads the valid measurement flags, material level changes and their directions output from the screening status calculation stage, and also reads the current material level in the silo from the data acquisition stage. This refers to the fine crusher load limitation state formed by the discharge outlet constraint control link in the previous control cycle. Let the target material level in the silo be... , material level deviation The controller performs proportional, integral, and derivative calculations on the deviation to obtain the unrestricted speed requirement of the feed belt of the fine crusher. Then, it generates speed commands based on the minimum speed, maximum speed, and rate of change limits of the feed speed actuator. When the material level is higher than the target, the feed speed is increased to absorb the material in the bin; when the material level is lower than the target, the feed speed is decreased. When the fine crusher load limit status of the previous control cycle indicates that the fine crusher is already in the upper limit neighborhood, the speed command is maintained or limited to decrease to prevent the material level loop from continuing to force material exceeding its capacity into the fine crusher.

[0031] Furthermore, target material level The height can be set to 10m, and the target zone can be set to 9.7m to 10.3m. The silo level control system outputs a feeding speed command and a level stability indicator. The former is executed by the feeding speed actuator and changes the fine crusher load for the next cycle, while the latter is used by the subsequent intermediate crusher coordination adjustment and equilibrium state determination stages. The limiting state of the previous cycle is used in the calculation of the silo level control system for this cycle, so that the level loop and the discharge outlet constraint control system work together without forming a cyclical dependency within the same cycle.

[0032] S4. Adjust the discharge port of the fine crusher according to the return material ratio and the fine crusher load, and generate a discharge port instruction within the mechanical range and the upper limit of the return material constraint. The collaborative controller normalizes the crushing chamber material level or power from the fine crusher load detector into a load feedback value. and the target value of fine crusher load. Comparison. When either the crushing chamber level or power is chosen as the primary feedback, the other measured quantity can be used as the over-limit interlock quantity; the controller generates the unconstrained demand for the fine crusher discharge port based on the load deviation. When the load is higher than the target, a request is made to expand the discharge opening; when the load is lower than the target, the discharge opening is allowed to be reduced within the mechanical range. The discharge opening constraint control link does not read the feeding rate requirement of the silo level control link in the current cycle. Instead, it reserves the limiting state formed in the current cycle for use by the silo level control link in the next control cycle, thereby maintaining a fixed order of operations.

[0033] The upper limit of the fine crusher's discharge opening is not a fixed mechanical limit, but is determined by the return material ratio calibration relationship. During calibration, several candidate discharge openings are maintained sequentially within the equipment's allowable range, waiting for the pre-screen flow rate and return material flow rate to reach a steady state. The return material ratio corresponding to each candidate discharge opening is recorded. The records are arranged from low to high according to the return material ratio, resulting in a table of return material ratios and discharge opening upper limits that do not increase when the return material ratio increases. This is obtained from the screening state calculation during operation. Interpolation is performed between adjacent calibration points. When the value exceeds the calibration range, the upper limit of the discharge outlet of the corresponding low-end or high-end calibration point is used, without extrapolation to the interval, to obtain the upper limit of the return material constraint. ; and then the upper limit of machinery Take the smaller value to form the current allowed upper limit. Fine crushing discharge port command. satisfy:

[0034] in, Indicates the first The fine crushing discharge port instruction for each cycle. This represents the unconstrained demand given by the closed-loop load of the fine crusher. and These represent the lower and upper limits of the machinery used for fine crushing discharge outlets, respectively. This indicates the current allowable upper limit given by the return ratio calibration relationship; the amount of each discharge outlet is expressed in millimeters. and These represent taking the minimum and maximum values, respectively.

[0035] Furthermore, the mechanical range of the fine crusher's discharge opening can be set from 16mm to 28mm. The discharge opening constraint control link outputs the discharge opening command, unconstrained demand, current allowable upper limit, and fine crusher load limit status, and forwards the actual position of the fine crusher's discharge opening obtained by the data acquisition link. The discharge opening command is executed by the fine crusher's discharge opening actuator. The unconstrained demand, current allowable upper limit, and actual position are compared by the subsequent intermediate crusher coordination adjustment link to identify the fine crusher's adjustment margin. The limit status is taken by the silo level control link for the next cycle. Thus, the return material constraint ensures that the action to improve the instantaneous throughput capacity of the fine crusher is coordinated with the cyclic load of the circular vibrating screen.

[0036] S5. Generate downstream capacity alarms based on the actual location of the fine crusher discharge outlet, unconstrained demand, and current allowable upper limit, and adjust the intermediate crusher accordingly; If the difference between the actual location of the fine crusher's discharge outlet and the current allowable upper limit is not greater than the location tolerance, and the unconstrained demand is still greater than the current allowable upper limit plus the demand retracement, and this condition is maintained continuously for the preset time... The collaborative controller will display the alarm status. Set to 1, corresponding to XPJ-Alarm; when unconstrained demand falls below the allowable upper limit minus the release retracement and maintains the release time, Set to 0. Where, Indicates the alarm duration, in seconds. The state variable is either 0 or 1. The preferred position tolerance is 1.5 mm; the preferred hysteresis is 1 mm; and the preferred release hysteresis is 2 mm.

[0037] Preferably, the alarm holding time It can be set to 20 seconds. This judgment uses both "reaching the allowable limit" and "still needing to expand" as alarm conditions, which can distinguish between short-term location approaching the limit and insufficient continuous processing capacity.

[0038] The intermediate crusher's coordinated adjustment mechanism uses the stable material level indicator output from the silo level control mechanism, the fine crushing adjustment margin output from the discharge outlet constraint control mechanism, the alarm status, and the current load of the intermediate crusher generated by the data acquisition mechanism as inputs for adjustment. During initialization, the intermediate crusher discharge outlet command is set to its maximum mechanical allowable range; preferably, the mechanical range of the intermediate crusher discharge outlet can be set to 30mm to 45mm, and is initially set to 45mm. =0, the material level in the fine crusher's hopper is within the target zone, and the fine crusher's load has not exceeded the limit. When the feed rate is less than 1, the feed rate is increased by the intermediate crusher feed actuator in preset small increments, and a stable waiting period follows each increase. <1 and When =1, the controller maintains the current feed rate of the intermediate crusher, stops subsequent increments, and outputs a command to reduce the adjustment step size by one step to the intermediate crusher discharge outlet actuator, where the adjustment step size is preferably 1mm; if the equipment control authority only allows manual confirmation, the same discharge outlet reduction prompt is output while maintaining the feed rate. The intermediate crusher coordinated adjustment link outputs the intermediate crusher feed command, the intermediate crusher discharge outlet command, and the coordination status. The first two commands are executed by the intermediate crusher feed actuator and the intermediate crusher discharge outlet actuator, respectively, and the coordination status is taken by the subsequent equilibrium status determination link; the alarm gate transmits the processing surplus of the fine crushing and screening closed circuit to the intermediate crusher adjustment to prevent the upstream from continuing to increase the feed rate and aggravating the downstream material accumulation.

[0039] S6. Determine the load balance status based on the coordination status, screening status, material level stability indicator, and current load of the intermediate crusher; when When the following conditions are met: 1. XPJ-Alarm is deactivated; 2. The material level in the fine crusher hopper is within the target zone; 3. The absolute value of the material level change is not greater than the stable threshold; 4. The evaluation time is continuously preset for a set time; 5. The controller outputs a rated balanced state, where the stable threshold is preferably 0.2 and the evaluation time is preferably 60 seconds. <1, but after the discharge port of the intermediate crusher is reduced and stabilized, if the alarm is cleared, the material level is stable, and the instantaneous flow rate of qualified material under the screen is maintained or increased, then the output is in a limited equilibrium state and the current feed rate of the intermediate crusher is maintained. When any condition leaves the corresponding hysteresis zone, the equilibrium state determination link redirects the next control cycle to the data acquisition link and retains the previous valid state as the initial value. Thus, changes in power, material level, or return material caused by changes in ore hardness will re-form control actions along the data acquisition to the various processing links of the intermediate crusher's coordinated adjustment. The equilibrium state output by the equilibrium state determination link is used for operation display, interlocking, and permission for the next cycle's feed increment, completing the closed-loop update between the intermediate crusher, fine crusher, and circular vibrating screen.

[0040] In the above method, the operating speed of the silo level ring can be faster than the feed increment of the intermediate crusher, and the control cycle of the fine crusher load ring can be faster than the material conveying cycle from the intermediate crusher to the circular vibrating screen. By setting different rate of change limits and stabilization waiting periods for each ring, the fine crusher discharge port can respond to the crushing chamber load first, the fine crusher feed belt can then stabilize the silo level, the intermediate crusher can adjust, and finally the upstream input can be changed based on the downstream capacity alarm, thus maintaining the control sequence consistent with the material propagation sequence.

[0041] Example 2 Please see Figure 2 As shown, this embodiment provides a closed-loop control system for load balancing of a medium and fine crusher and a circular vibrating screen, including a data acquisition unit, a flow calculation unit, a fine crusher material level control unit, a fine crusher load control unit, a medium crusher adjustment unit, and a status determination unit.

[0042] The data acquisition unit connects to the first belt scale, the second belt scale, the level gauge, and the fine crusher load detector, and also receives position or speed feedback from the feeding speed actuator, the fine crusher discharge actuator, the intermediate crusher feeding actuator, and the intermediate crusher discharge actuator. The data acquisition unit performs validity checks, filtering, and two-channel flow rate lag alignment on signals of the same period, generates a process status record, and outputs this record to the flow calculation unit, the fine crusher level control unit, and the fine crusher load control unit; simultaneously, it outputs the current feed rate of the intermediate crusher, fed back by the intermediate crusher feeding actuator, to the status determination unit.

[0043] The flow calculation unit reads the process status record generated by the acquisition unit, extracts the pre-screen flow and return flow after hysteresis alignment, and calculates the return ratio, the instantaneous flow of qualified material under the screen, the change in material level and its direction. Among them, the return ratio is output to the fine crusher load control unit, the change in material level, the direction of change and the measurement validity mark are output to the fine crusher material level control unit, and the return ratio and the instantaneous flow of qualified material under the screen are simultaneously output to the status determination unit.

[0044] The fine crusher material level control unit reads the material level in the fine crusher hopper, the target material level, and the limiting status formed by the fine crusher load control unit in the previous control cycle. After proportional, integral, and derivative calculations and limiting by the speed actuator, it generates a feeding speed command and sends it to the feeding speed actuator for execution. At the same time, the material level stability flag is sent to the intermediate crusher adjustment unit and the status determination unit.

[0045] The fine crusher load control unit reads the crushing chamber material level or power from the fine crusher load detector, and the return ratio output by the flow calculation unit. It calculates the unconstrained demand at the fine crusher discharge port, determines the upper limit of the return constraint based on the return ratio calibration relationship, and then combines this with the mechanical lower and upper limits of the fine crusher discharge port to form a limited discharge port instruction, which is sent to the fine crusher discharge port actuator for execution. This unit also sends the limited status formed in this cycle to the fine crusher material level control unit for use in the next control cycle, and sends the unconstrained demand, the current allowable upper limit, and the actual position of the fine crusher discharge port to the intermediate crusher adjustment unit.

[0046] The intermediate crusher adjustment unit generates XPJ-Alarm based on a continuous comparison of the actual position of the fine crusher discharge port, unconstrained demand, and the current allowable upper limit. It also combines the material level stability flag and status output by the fine crusher level control unit to determine the current load of the intermediate crusher, decide whether to increase or maintain the intermediate crusher feed rate, and the retraction of the intermediate crusher discharge port. The unit then outputs corresponding instructions to the intermediate crusher feed actuator and the intermediate crusher discharge port actuator, respectively.

[0047] The status determination unit determines the current load of the intermediate crusher based on the ratio of the current feed rate to the rated feed rate sent by the acquisition unit and outputs this value to the intermediate crusher adjustment unit. Simultaneously, it reads the screening status from the flow calculation unit, the level stability indicator from the fine crusher level control unit, and the alarm and coordination status from the intermediate crusher adjustment unit. After comprehensive judgment, it outputs a rated equilibrium status, a limited equilibrium status, or a continued adjustment status. This output, along with the current load of the intermediate crusher, is returned to the intermediate crusher adjustment unit as the basis for permitting the next feed increment and determining the load, and can also be sent to the operation display or interlocking interface.

[0048] Each unit can be implemented by a program segment in the same programmable controller, or it can be distributed among controllers that communicate with each other. Regardless of the implementation method, the aforementioned measurement records, control requirements, limiting status, alarm and equalization status are transmitted according to the same control cycle number to maintain the time consistency of the data.

[0049] The fine crushing load detector uses the crushing chamber level timer, which can directly use the target material level in the crushing chamber as the timer. When using a power detector, the ratio of actual power to rated power can be used as the power output. When both types of detectors are available, one type can be selected as the main feedback for the closed loop, and the other type can be used for over-limit blocking. The relationship between the return ratio and the upper limit of the discharge port can also be represented by a segmented constant table. As long as a higher return ratio does not correspond to an increased upper limit of the allowable discharge port, the direction of the return constraint can be kept consistent.

[0050] The small-scale retraction action at the discharge port of the medium-sized crusher can be automatically executed by the discharge port actuator, or, when control authority is limited, the collaborative controller can output an operation prompt with the target discharge port and wait for position feedback. Both methods use the XPJ-Alarm, feed hold, and discharge port position feedback to form the same coordination logic. The foregoing embodiments are used to illustrate the present invention, and the specific drive form of the actuator, the deployment location of the controller, and the communication method can be adjusted while maintaining the data and control relationship defined in the claims.

[0051] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A closed-loop control method for load balancing of a medium-fine crusher and a circular vibrating screen, characterized in that, include: Acquire process measurements and equipment boundaries for the same control cycle to form a process status record; The return ratio and the instantaneous flow rate of qualified material under the screen are calculated based on the pre-screen flow rate and the return flow rate to form the screening state; The feed belt speed command for the fine crusher is generated based on the deviation between the material level in the fine crusher hopper and the target material level, and a material level stability indicator is formed; the discharge port of the fine crusher is adjusted according to the return ratio and the fine crusher load, and a discharge port command is formed within the mechanical range and the upper limit of the return constraint. The downstream capacity alarm is generated based on the actual location of the fine crusher discharge outlet, unconstrained demand, and the current allowable upper limit, and the intermediate crusher is adjusted accordingly; the load balance status is determined based on the coordination status, screening status, material level stability indicator, and the current load of the intermediate crusher.

2. The method for load balancing closed-loop control of a medium-fine crusher and a circular vibrating screen according to claim 1, characterized in that, Acquire process measurements and equipment boundaries for the same control cycle to form a process status record, including: Receive the original value of the pre-screen flow rate, the original value of the return flow rate, the material level in the fine crusher's hopper, the load detection value of the fine crusher, the current feed rate of the intermediate crusher, the actual position of the fine crusher's discharge port, and the actual position of the intermediate crusher's discharge port; Check the timestamp, range, and actuator feedback of each measurement value. Measurement values ​​that meet the valid conditions are processed by first-order filtering. When a measurement fails, retain the previous valid setpoint and pause the ore feed increment until a preset number of valid samples are obtained continuously. The number of cycles corresponding to the lag between screening and return material conveying is determined based on the belt length and speed. The pre-screen flow filtering sequence is moved according to the number of cycles so that the pre-screen flow and return material flow being compared correspond to the same batch of material. The current load of the intermediate crusher is determined by the ratio of the current feed rate to the rated feed rate.

3. The method for load balancing closed-loop control of a medium-fine crusher and a circular vibrating screen according to claim 1, characterized in that, The return ratio and the instantaneous flow rate of qualified material under the screen are calculated based on the pre-screening flow rate and the return flow rate to form the screening state, including: The larger of the aligned in-screen flow rate and the preset minimum effective in-screen flow rate is used as the denominator, and the return flow rate is used as the numerator to calculate the return ratio. The difference between the pre-screen flow rate and the return flow rate is taken as the instantaneous flow rate of the qualified material under the screen. The change in material level is calculated by the difference between the current material level in the silo and the material level in the silo before the preset cycle, and the direction of the change in material level is determined by the sign of the change in material level.

4. The method for load balancing closed-loop control of a medium-fine crusher and a circular vibrating screen according to claim 1, characterized in that, Based on the deviation between the material level in the fine crusher's hopper and the target material level, a speed command for the fine crusher's feed belt is generated, and a material level stability indicator is formed, including: The difference between the current material level in the silo and the target material level is taken as the material level deviation. Proportional, integral and differential calculations are performed on the material level deviation to obtain the unlimited speed requirement of the feed belt of the fine crusher. The unlimited speed demand is limited according to the minimum speed, maximum speed and rate of change of the feed speed actuator to form a speed command; When the fine crusher load limit status of the previous control cycle indicates that the fine crusher is already in the upper limit range, the speed command is maintained or limited to decrease. When the material level in the silo is stable within the target zone and the absolute value of the material level change is not greater than the preset stability threshold and continues for a preset evaluation time, a material level stability indicator is formed.

5. The method for load balancing closed-loop control of a medium-fine crusher and a circular vibrating screen according to claim 1, characterized in that, Adjust the fine crusher discharge port according to the return material ratio and fine crusher load, and generate discharge port instructions within the mechanical range and the upper limit of the return material constraint, including: The load detection value of the fine crusher is normalized into a load feedback value and compared with the target value of the fine crusher load. Based on the load deviation, the unconstrained demand of the fine crusher discharge outlet is generated. The upper limit of the return material constraint is determined based on the return material ratio calibration relationship, and then the smaller value is taken from the mechanical upper limit to form the current allowable upper limit; the return material ratio calibration relationship is obtained through calibration tests, and the upper limit of the discharge port does not increase when the return material ratio increases; The unconstrained demand limit is set between the lower limit of the machinery and the current upper limit, forming a discharge port instruction; Based on the discharge port instruction, unconstrained demand, current allowable upper limit, and actual location of the fine crusher discharge port, a fine crusher load limit state is formed for use in the next control cycle.

6. The method for load balancing closed-loop control of a medium-fine crusher and a circular vibrating screen according to claim 1, characterized in that, Based on the actual location of the fine crusher's discharge outlet, unconstrained demand, and the current allowable upper limit, a downstream capacity alarm is generated, and the intermediate crusher is adjusted accordingly, including: If the difference between the actual location of the fine crusher discharge outlet and the current allowable upper limit is not greater than the location tolerance, and the unconstrained demand is still greater than the current allowable upper limit plus the demand hysteresis, and the preset alarm holding time is maintained continuously, then the alarm status will be set to valid; when the unconstrained demand falls back to below the allowable upper limit minus the release hysteresis and is maintained for the release time, the alarm status will be released. When the alarm is cleared, the material level stability indicator is valid, the fine crusher load has not exceeded the limit, and the current load of the intermediate crusher is less than the rated load, the feed rate of the intermediate crusher is increased according to the preset step size, and a stable waiting period is entered after each increase. When the current load of the intermediate crusher is less than the rated load and the alarm status is valid, the current feed rate of the intermediate crusher is maintained, and a small feed instruction is sent to the actuator at the discharge port of the intermediate crusher.

7. A load-balanced closed-loop control system for a medium-fine crusher and a circular vibrating screen, characterized in that, include: The acquisition unit is used to acquire process measurement values ​​and equipment boundaries in the same control cycle to form a process status record; The flow calculation unit is used to calculate the return ratio and the instantaneous flow of qualified material under the screen based on the pre-screen flow and return flow, thus forming the screening state; The fine crusher material level control unit is used to generate a fine crusher feed belt speed command based on the deviation between the material level in the fine crusher hopper and the target material level, and to form a material level stability indicator. The fine crushing load control unit is used to adjust the fine crusher discharge port according to the return ratio and fine crushing load, and generate discharge port commands within the mechanical range and the upper limit of the return constraint. The intermediate crusher adjustment unit is used to generate downstream capacity alarms based on the actual location of the fine crusher discharge outlet, unconstrained demand, and the current allowable upper limit, and adjust the intermediate crusher accordingly. The status determination unit is used to determine the load balance status based on the coordination status, screening status, material level stability indicator, and the current load of the intermediate crusher.

8. The load-balanced closed-loop control system for a medium-fine crusher and a circular vibrating screen according to claim 7, characterized in that, The acquisition unit checks the timestamp, range, and actuator feedback of each measurement value. Measurement values ​​that meet the valid conditions are processed by first-order filtering. The number of cycles corresponding to the lag between screening and return material conveying is determined based on the belt length and speed. The pre-screen flow filtering sequence is moved according to the number of cycles so that the pre-screen flow and return material flow being compared correspond to the same batch of material. The current load of the intermediate crusher is formed by the ratio of the current feed rate to the rated feed rate. When the measurement fails, the previous valid setpoint is maintained and the feed increment is paused until a preset number of valid samples are continuously obtained.

9. A load-balanced closed-loop control system for a medium-fine crusher and a circular vibrating screen according to claim 7, characterized in that, The fine crushing load control unit normalizes the fine crushing load detection value into a load feedback value and compares it with the fine crushing load target value. Based on the load deviation, it generates the unconstrained demand of the fine crushing discharge outlet. The upper limit of the return material constraint is determined based on the return material ratio calibration relationship, and then the smaller value is taken from the upper limit of the machinery to form the current allowable upper limit; The unconstrained demand limit will be used to form a discharge port instruction between the mechanical lower limit and the current allowed upper limit; Based on the discharge port instruction, unconstrained demand, current allowable upper limit, and actual location of the fine crusher discharge port, a fine crusher load limit state is formed for use in the next control cycle; The fine crusher level control unit uses the difference between the current material level in the hopper and the target material level as the material level deviation. It performs proportional, integral, and derivative calculations on the material level deviation to obtain the unlimited speed requirement of the fine crusher feed belt. It limits the unlimited speed requirement to form a speed command according to the minimum speed, maximum speed, and rate of change limit of the feed speed actuator. When the fine crusher load limit status of the previous control cycle indicates that the fine crusher is already in the upper limit neighborhood, the speed command is maintained or limited to decrease.

10. A load-balanced closed-loop control system for a medium-fine crusher and a circular vibrating screen according to claim 7, characterized in that, The intermediate crusher adjustment unit sets the alarm status to valid when the difference between the actual position of the fine crusher discharge port and the current allowable upper limit is not greater than the position tolerance, and the unconstrained demand is still greater than the current allowable upper limit plus the demand hysteresis, and the preset alarm holding time is maintained continuously. When the unconstrained demand falls back to the allowable upper limit minus the release hysteresis and is maintained for the release time, the alarm status is released. When the alarm status is released, the material level stability indicator is valid, the fine crusher load has not exceeded the limit, and the current load of the intermediate crusher is less than the rated load, the feed rate of the intermediate crusher is increased by a preset step size. When the current load of the intermediate crusher is less than the rated load and the alarm status is valid, the current feed rate of the intermediate crusher is maintained and an instruction to reduce the discharge port of the intermediate crusher is output.

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