Detection system for underflow concentration of thickener

Abstract

The invention relates to the technical field of tailing disposal, and discloses a thickener underflow concentration detection system, comprising: a data acquisition module for calculating to obtain a logarithmic count rate and synchronously obtaining mother liquor density and solid true density; the data calculation module is used for calculating to obtain the in-section deposition slope and the baseline floating rate; the logarithmic counting rate purification module is used for calculating to obtain a deposition accumulation item and an abrasion baseline item according to the in-section deposition slope and the baseline floating rate, and calculating to obtain a purified logarithmic counting rate according to the deposition accumulation item and the abrasion baseline item; the underflow slurry density conversion module is used for converting the purified logarithmic counting rate into the underflow slurry density; and the concentration detection module is used for converting the density of the underflow slurry into the mass fraction of the underflow solid according to the density of the mother liquor and the true density of the solid. Through a systematic signal processing and data conversion mechanism, interference of geometric factors such as pipe wall abrasion and deposition in a pipe on a detection signal is effectively eliminated, and the accuracy and reliability of underflow concentration detection of the thickener are greatly improved.

Description

Technical Field

[0001] This invention relates to the field of tailings disposal technology, and more specifically, to a detection system for the concentration of thickener underflow. Background Technology

[0002] In industries such as mineral processing and metallurgy, thickeners are core equipment for solid-liquid separation of slurry. Their underflow concentration directly determines the efficiency of subsequent processes such as filtration and drying, as well as the quality of the final product. Therefore, accurate detection of underflow concentration is crucial. Currently, the industry mainstream uses radiation densitometers for detection. The principle is based on the attenuation characteristics of gamma rays penetrating the slurry. By detecting the original count rate after penetration, logarithmic transformation is performed, and combined with calibration parameters, the slurry density is calculated and then converted into underflow concentration.

[0003] However, in actual operation, this detection method is easily affected by the geometric changes of the pipeline. The specific technical problems are as follows: On the one hand, solid particles in the slurry will continue to deposit on the inner wall of the underflow pipeline. The thickening of the deposit layer will enhance the attenuation effect of gamma rays, causing the logarithmic count rate to gradually decrease over time. This decrease is not caused by the increase in slurry concentration, but by the physical barrier of the deposit layer. On the other hand, the pipeline will wear down due to long-term scouring by the slurry. The thinning of the pipe wall will weaken the attenuation of gamma rays, causing the baseline of the logarithmic count rate to drift slowly upward. This drift is unrelated to changes in slurry concentration.

[0004] Existing detection methods lack effective removal mechanisms to address the aforementioned geometric factors. They directly use the raw logarithmic count rate, which contains interference, for concentration conversion. This often leads to situations where a decrease in the count rate caused by deposition is misinterpreted as an increase in concentration, or baseline drift caused by wear is misinterpreted as a decrease in concentration. Furthermore, cleaning or shutdown operations during maintenance can remove the deposit layer, causing the count rate to suddenly reset and rise, further disrupting the signal pattern. Simple calibration cannot eliminate accumulated errors, ultimately resulting in significant deviations in the detection results. This severely affects the precise control of process parameters such as underflow pump speed and flocculant dosage, reducing production stability and efficiency. Summary of the Invention

[0005] This invention provides a system for detecting the concentration of underflow from a thickener, thereby solving the technical problems mentioned in the background section.

[0006] This invention provides a system for detecting the concentration of underflow from a thickener, comprising:

[0007] The data acquisition module is used to collect the raw count rate of the thickener bottom flow and convert it into a logarithmic count rate, record operation and maintenance intervention events to divide the circulation section, and simultaneously obtain the mother liquor density and solid true density.

[0008] The data calculation module is used to linearly fit the log count rate within each cycle segment according to a preset sliding window to obtain the deposition slope within the segment, and to extract the peak value of the log count rate at the beginning of each cycle and obtain the baseline drift rate by time regression.

[0009] The logarithmic count rate purification module is used to calculate the deposition accumulation term and wear baseline term based on the deposition slope and baseline drift rate within the segment, and to calculate the purified logarithmic count rate accordingly.

[0010] The underflow slurry density conversion module is used to convert the purified logarithmic count rate into underflow slurry density based on the densitometer calibration parameters.

[0011] Densitometer calibration parameters include logarithmic intercept and density proportionality coefficient;

[0012] The concentration detection module is used to convert the density of the underflow slurry into the mass fraction of the underflow solids based on the density of the mother liquor and the true density of the solids, and use this as the concentration detection result.

[0013] Furthermore, a unified sampling benchmark is set, including sampling interval and start time. The raw count rate of the underflow pipeline is continuously obtained by a radiation density meter according to the sampling benchmark, and only the raw count rate with a value greater than zero is retained. Then, the logarithmic count rate is obtained by performing natural logarithmic calculation on each. Operation and maintenance intervention events include recording cleaning and shutdown events. The continuous running time between two adjacent operation and maintenance intervention events is used as the boundary to obtain the cyclic segment, and the start and end time of each cyclic segment is recorded.

[0014] Furthermore, the difference between the logarithmic count rate at each sampling time within each cyclic segment and the logarithmic count rate at each sampling time shifted forward by a preset sliding window is calculated, and the ratio of this difference to the preset sliding window length is used as the intra-segment deposition slope at each sampling time.

[0015] Furthermore, the maximum value of the logarithmic count rate of the preset sliding window within each loop segment is obtained as the loop start representative value. The difference between the loop start representative value and the logarithmic count rate at the start time of each loop segment is calculated. Then, the difference between the time corresponding to the maximum value of the logarithmic count rate and the start time of each loop segment is calculated. The ratio of the two differences is used as the window drift value of the preset sliding window. The average value of the window drift values ​​of all preset sliding windows within the loop segment is used as the baseline drift rate.

[0016] Furthermore, the deposition slope within any sampling time of the circulation segment is multiplied by the difference between the sampling time and the start time of the circulation segment to obtain the deposition accumulation term; the baseline drift rate of the circulation segment is multiplied by the difference between the end time and the start time of the circulation segment to obtain the wear baseline term.

[0017] Furthermore, the purified logarithmic count rate is obtained by subtracting the deposition accumulation term and wear baseline term at the corresponding time from the logarithmic count rate at any sampling time in the cyclic section.

[0018] Furthermore, the difference between the logarithmic intercept and the logarithmic count rate after purification corresponding to each sampling time is calculated, and then the ratio between this difference and the density proportionality coefficient is calculated to obtain the underflow slurry density at that sampling time. The logarithmic intercept and the density proportionality coefficient are obtained by the two-point calibration method.

[0019] Furthermore, the two-point calibration method includes the following steps:

[0020] Step S201: Select two stable operating conditions with known densities and sufficiently large differences;

[0021] The first working condition is the mother liquor working condition, and the corresponding known density is the mother liquor density. The second working condition is the high solids content or standard solution working condition, and the corresponding known density is the high solids content or standard solution density, and the high solids content or standard solution density is greater than the mother liquor density.

[0022] Step S202: Calculate the average value of the purification log count rate for the two stable operating conditions;

[0023] Within the stable time window of the first operating condition, the average value of the logarithmic count rate after purification is taken and recorded as the average value of the first purification logarithmic count rate.

[0024] Within the stable time window of the second operating condition, the average value of the logarithmic count rate after purification is taken and recorded as the average value of the second purification logarithmic count rate.

[0025] The length of the stable time window is a custom parameter, which is a positive integer multiple of the sampling interval, and at the same time satisfies the condition that the fluctuation of the logarithmic count rate after purification within the time window does not exceed 2% of its average value;

[0026] Step S203: Calculate the density proportionality coefficient based on the average value of the purification log count rate under two stable operating conditions.

[0027] The first difference is obtained by subtracting the average value of the second logarithmic count rate from the average value of the first purification logarithmic count rate. The second difference is obtained by subtracting the known density of the first working condition from the known density of the second working condition. The density ratio coefficient is obtained by dividing the first difference by the second difference.

[0028] Step S204: Calculate the logarithmic intercept based on the density proportionality coefficient;

[0029] Multiply the density proportionality coefficient by the known density of the first working condition, and then add it to the average value of the first purification logarithmic count rate to obtain the logarithmic intercept.

[0030] Further, the third difference is obtained by subtracting the density ratio coefficient from the logarithmic intercept and multiplying it by the known density of the second working condition. The absolute value of the difference between the third difference and the average value of the second purification logarithmic count rate is calculated. If the absolute value is less than or equal to the residual threshold, the logarithmic intercept and density ratio coefficient are deemed valid. Otherwise, the process returns to step S201 and is re-executed. The residual threshold is a user-defined parameter.

[0031] Furthermore, the difference between the density of the underflow slurry and the density of the mother liquor is first calculated at each sampling time, and then the difference between the true density of the solids and the density of the mother liquor is calculated. The ratio of the two differences is taken as the solid volume fraction at that sampling time. Then, the solid volume fraction at that sampling time is multiplied by the true density of the solids and divided by the density of the underflow slurry to obtain the underflow solid mass fraction at that sampling time.

[0032] The beneficial effects of this invention are as follows: This invention effectively eliminates the interference of geometric factors such as pipe wall wear and in-pipe deposition on the detection signal through a systematic signal processing and data conversion mechanism, significantly improving the accuracy and reliability of thickener underflow concentration detection. First, the original underflow count rate is collected and converted into a logarithmic count rate. The circulation section is divided by recording maintenance events such as cleaning and shutdown, and the mother liquor density and solid true density are obtained simultaneously. Then, the deposition slope and baseline drift rate within the circulation section are calculated. Based on this, the deposition accumulation term and wear baseline term are deducted to obtain the purified logarithmic count rate, which only reflects the slurry characteristics. The accurate underflow slurry density is calculated by combining the logarithmic intercept calibrated at two points with the density proportionality coefficient, and converted into the underflow solid mass fraction. This can be directly used for precise control of underflow pump operation, flocculant addition, and other process steps. At the same time, the circulation section division and parameter verification mechanism ensures traceability of the detection process and convenient maintenance, significantly improving production stability and efficiency. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of a system for detecting the concentration of underflow from a thickener according to the present invention;

[0034] Figure 2 This is a flowchart of the two-point calibration method of the present invention.

[0035] In the diagram: Data acquisition module 101, data calculation module 102, logarithmic count rate purification module 103, underflow slurry density conversion module 104, concentration detection module 105. Detailed Implementation

[0036] The subject matter described herein will now be discussed with reference to exemplary embodiments. It should be understood that these embodiments are discussed only to enable those skilled in the art to better understand and implement the subject matter described herein, and changes may be made to the function and arrangement of the elements discussed without departing from the scope of this specification. Various processes or components may be omitted, substituted, or added as needed in the examples. Furthermore, features described in some examples may be combined in other examples.

[0037] It should be noted that, unless otherwise defined, the technical or scientific terms used in one or more embodiments of the present invention should have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms "first," "second," and similar terms used in one or more embodiments of the present invention do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" indicate that the element or object preceding the term encompasses the elements or objects listed following the term and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0038] like Figures 1-2 As shown, a system for detecting the concentration of underflow from a thickener includes:

[0039] Data acquisition module 101 is used to acquire the raw count rate of the thickener bottom flow and convert it into a logarithmic count rate, record operation and maintenance intervention events to divide the circulation section, and simultaneously acquire the mother liquor density and solid true density.

[0040] The data calculation module 102 is used to linearly fit the log count rate according to a preset sliding window in each cycle segment to obtain the deposition slope within the segment, and to extract the peak value of the log count rate at the beginning of each cycle and obtain the baseline drift rate by time regression.

[0041] The logarithmic count rate purification module 103 is used to calculate the deposition accumulation term and the wear baseline term based on the deposition slope and baseline drift rate within the segment, and to calculate the purified logarithmic count rate accordingly.

[0042] The underflow slurry density conversion module 104 is used to convert the purified logarithmic count rate into the underflow slurry density based on the densitometer calibration parameters.

[0043] Densitometer calibration parameters include logarithmic intercept and density proportionality coefficient;

[0044] The concentration detection module 105 is used to convert the density of the underflow slurry into the mass fraction of the underflow solids based on the density of the mother liquor and the true density of the solids, and use this as the concentration detection result.

[0045] In one embodiment of the present invention, a unified sampling benchmark is set, including sampling interval and start time. The original count rate of the underflow pipeline is continuously obtained by a radiation density meter according to the sampling benchmark, and only the original count rate with a value greater than zero is retained. Then, the logarithmic count rate is obtained by performing natural logarithmic calculation on each count rate. The operation and maintenance intervention events include recording cleaning and shutdown events. The continuous running time between two adjacent operation and maintenance intervention events is used as the boundary to divide the loop into segments, and the start and end times of each loop segment are recorded.

[0046] It should be noted that the raw count rate of the thickener underflow represents the number of particles per second detected by a radiation densitometer after gamma rays penetrate the slurry in the thickener underflow pipeline. The logarithmic count rate converts the exponential decay relationship of gamma rays penetrating the slurry into a linear relationship, facilitating subsequent separation of geometric interference factors such as pipe wall wear and in-pipe deposition, as well as the influence of slurry concentration changes. The mother liquor density represents the density of the liquid medium in the thickener underflow slurry, i.e., the density of the pure liquid phase excluding solid particles, and is measured by laboratory personnel according to industry standard testing methods, such as using the density bottle method or the densitometer method to test the underflow mother liquor sample. The true density of solids represents the true density of solid particles in the thickener underflow slurry. Density, the density of a pure substance excluding the internal pores of solid particles, reflects the material properties of the solid itself. It can be obtained through laboratory testing, with common methods including the specific gravity bottle method or the gas displacement method, which involves purifying the solid particle sample in the underflow and then measuring its true density. Operational intervention events mainly refer to operations such as cleaning the underflow pipe of the thickener or shutting down the equipment. These operations directly lead to the removal of the deposit layer inside the pipe, causing a momentary reset-like increase in the logarithmic count rate. Based on this, the circulation section is obtained, which facilitates focused analysis of the growth pattern of the deposit inside the pipe in the circulation section, that is, the complete process of the gradual formation of the deposit layer after cleaning and shutdown, avoiding detection and control deviations caused by interference and misjudgment.

[0047] In one embodiment of the present invention, the difference between the logarithmic count rate at each sampling time within each cyclic segment and the logarithmic count rate at each sampling time shifted forward by a preset sliding window is calculated, and the ratio of this difference to the preset sliding window length is used as the intra-segment deposition slope at each sampling time.

[0048] In one embodiment of the present invention, the maximum value of the logarithmic count rate of a preset sliding window within each loop segment is obtained as the loop start representative value. The difference between the loop start representative value and the logarithmic count rate at the start time of each loop segment is calculated. Then, the difference between the time corresponding to the maximum value of the logarithmic count rate and the start time of each loop segment is calculated. The ratio of the two differences is used as the window drift value of the preset sliding window. The average value of the window drift values ​​of all preset sliding windows within the loop segment is used as the baseline drift rate.

[0049] Specifically, the intra-segment deposition slope at the t-th sampling time of the k-th cycle segment. The calculation formula is as follows:

[0050] ,in Indicates the preset sliding window length. This represents the logarithmic count rate at the t-th sampling time of the k-th cyclic segment. This represents the logarithmic count rate of the k-th cyclic segment, shifted forward by one preset sliding window at the t-th sampling time.

[0051] Specifically, the baseline drift rate of the k-th cyclic segment The calculation formula is as follows:

[0052] ,in and Let represent the set and total number of preset sliding windows in the k-th loop segment, respectively. This represents the starting value of the j-th preset sliding window in the k-th loop segment. express The corresponding time, The logarithmic count rate represents the start time of the k-th cyclic segment. This indicates the start time of the k-th cyclic segment.

[0053] It should be noted that, since the thickening of the deposition layer inside the pipe enhances the attenuation of gamma rays, causing the logarithmic count rate to decrease, the deposition slope within the segment can directly quantify the rate at which the gradual thickening of the deposition layer on the inner wall of the pipe affects the logarithmic count rate over time. Conversely, since pipe wall wear reduces the wall thickness, the attenuation of gamma rays during penetration decreases, and the logarithmic count rate slowly increases over time. Therefore, the baseline drift rate can directly quantify the rate at which long-term pipe wall wear affects the baseline logarithmic count rate. The length of the preset sliding window is a custom parameter, a positive integer multiple of the sampling interval, but cannot exceed the length of the cyclic segment. Preferably, the length of the preset sliding window is set to the rounded-up of 1 / 10 of the cyclic segment length, and the step size of the preset sliding window is equal to the length of the preset sliding window, i.e., non-overlapping sliding. Non-overlapping windows ensure the independence of each calculation interval, meaning that the deposition slope within the segment at each sampling moment corresponds to a non-repeating time window, guaranteeing the clarity of the slope calculation and the consistency of the results.

[0054] In one embodiment of the present invention, the deposition slope within a cyclic segment at any sampling time is multiplied by the difference between the sampling time and the start time of the cyclic segment to obtain a deposition accumulation term; the baseline drift rate of the cyclic segment is multiplied by the difference between the end time and the start time of the cyclic segment to obtain a wear baseline term.

[0055] In one embodiment of the present invention, the purified logarithmic count rate is obtained by subtracting the deposition accumulation term and the wear baseline term at the corresponding time from the logarithmic count rate at any sampling time of the cyclic segment.

[0056] It should be noted that the deposition accumulation term is used to quantify the total amount of logarithmic count rate decrease caused by the thickening of the deposition layer on the inner wall of the pipe over time. This serves as the amount of deposition interference that needs to be removed from the observed logarithmic count rate, avoiding the misjudgment of the decrease in logarithmic count rate caused by deposition as a change in slurry density. The wear baseline term is used to quantify the total amount of slow increase in the logarithmic count rate baseline caused by pipe wall wear. This serves as the amount of wear interference that needs to be removed from the observed logarithmic count rate, avoiding the misjudgment of the increase in logarithmic count rate caused by wear as a change in slurry density. The purified logarithmic count rate is used to remove the interference of two types of geometric factors, namely pipe wall wear and in-pipe deposition, on the logarithmic count rate. This ensures that the obtained purified logarithmic count rate only reflects information on the slurry's own factors (including underflow density, mother liquor density, solid content, etc.), providing accurate input data for the subsequent conversion of the logarithmic count rate into underflow concentration.

[0057] In one embodiment of the present invention, the difference between the logarithmic intercept and the logarithmic count rate after purification corresponding to each sampling time is calculated, and then the ratio between the difference and the density proportionality coefficient is calculated to obtain the underflow slurry density at that sampling time, wherein the logarithmic intercept and the density proportionality coefficient are obtained by a two-point calibration method.

[0058] It should be noted that the underflow slurry density represents the mass per unit volume of the slurry at the underflow outlet of the thickener. This slurry contains solid particles and mother liquor, and its value directly reflects the degree of mixing and compaction of solid particles and mother liquor in the underflow slurry. It is the core parameter for subsequent calculation of the underflow solid mass fraction.

[0059] In one embodiment of the present invention, such as Figure 2 As shown, the two-point calibration method includes the following steps:

[0060] Step S201: Select two stable operating conditions with known densities and sufficiently large differences;

[0061] The first working condition is the mother liquor working condition, and the corresponding known density is the mother liquor density. The second working condition is the high solids content or standard solution working condition, and the corresponding known density is the high solids content or standard solution density, and the high solids content or standard solution density is greater than the mother liquor density.

[0062] Step S202: Calculate the average value of the purification log count rate for the two stable operating conditions;

[0063] Within the stable time window of the first operating condition, the average value of the logarithmic count rate after purification is taken and recorded as the average value of the first purification logarithmic count rate.

[0064] Within the stable time window of the second operating condition, the average value of the logarithmic count rate after purification is taken and recorded as the average value of the second purification logarithmic count rate.

[0065] The length of the stable time window is a custom parameter, which is a positive integer multiple of the sampling interval, and at the same time satisfies that the fluctuation of the log count rate after purification within the time window does not exceed 2% of its average value. Preferably, the length of the stable time window is set to 60 seconds.

[0066] Step S203: Calculate the density proportionality coefficient based on the average value of the purification log count rate under two stable operating conditions.

[0067] The first difference is obtained by subtracting the average value of the second logarithmic count rate from the average value of the first purification logarithmic count rate. The second difference is obtained by subtracting the known density of the first working condition from the known density of the second working condition. The density ratio coefficient is obtained by dividing the first difference by the second difference.

[0068] Step S204: Calculate the logarithmic intercept based on the density proportionality coefficient;

[0069] Multiply the density proportionality coefficient by the known density of the first working condition, and then add it to the average value of the first purification logarithmic count rate to obtain the logarithmic intercept.

[0070] In one embodiment of the present invention, a third difference is obtained by subtracting the density ratio coefficient from the logarithmic intercept and multiplying it by the known density of the second working condition. The absolute value of the difference between the third difference and the average value of the second purification logarithmic count rate is calculated. If the absolute value is less than or equal to the residual threshold, the logarithmic intercept and the density ratio coefficient are deemed valid. Otherwise, the process returns to step S201 and is re-executed. The residual threshold is a custom parameter. Preferably, the residual threshold is set to 5% of the absolute value.

[0071] It should be noted that when gamma rays penetrate the slurry, their attenuation is exponentially related to the slurry density. After logarithmic transformation, the purified logarithmic count rate is linearly related to the slurry density. By selecting two stable operating conditions with known densities and sufficiently large differences, the average value of the purified logarithmic count rate is obtained within the stable time window of each operating condition. Using the above linear relationship, the intercept (i.e., logarithmic intercept) and slope (i.e., density proportionality coefficient) of this linear relationship are calculated using two known density values ​​and the corresponding average values ​​of the two purified logarithmic count rates. Thus, a quantitative conversion relationship between the purified logarithmic count rate and the underflow slurry density is established.

[0072] It should be noted that the logarithmic intercept represents the theoretical logarithmic count value when the underflow slurry density is zero in the linear relationship between the purified logarithmic count rate and the underflow slurry density. This value comprehensively reflects the influence of fixed factors such as gamma-ray source intensity, detector gain, and the geometry of the ray penetration path on the logarithmic count rate. The density proportionality coefficient represents the sensitivity coefficient of the logarithmic count rate as a function of the underflow slurry density in the linear relationship between the purified logarithmic count rate and the underflow slurry density. That is, the change in the purified logarithmic count rate caused by a unit change in the underflow slurry density. Its value is greater than zero, ensuring that the linear conversion between the purified logarithmic count rate and the underflow slurry density has a clear quantitative correspondence, and is used to accurately map the purified logarithmic count rate to the underflow slurry density.

[0073] In one embodiment of the present invention, the difference between the density of the underflow slurry and the density of the mother liquor at each sampling time is first calculated, and then the difference between the true density of the solids and the density of the mother liquor is calculated. The ratio of the two differences is used as the solid volume fraction at that sampling time. Then, the solid volume fraction at that sampling time is multiplied by the true density of the solids and divided by the density of the underflow slurry to obtain the underflow solid mass fraction at that sampling time.

[0074] Specifically, the mass fraction of bottom-flow solids at the t-th sampling time. The calculation formula is as follows:

[0075] ,in This represents the density of the underflow slurry at the t-th sampling time. Represents the true density of a solid;

[0076] Specifically, the solid volume fraction at the t-th sampling time. The calculation formula is as follows:

[0077] ,in This indicates the density of the mother liquor.

[0078] It should be noted that the solids volume fraction represents the proportion of the volume of solid particles in the thickener underflow slurry to the total volume of the slurry, and is a dimensionless parameter. The underflow solids mass fraction represents the proportion of the mass of solid particles in the thickener underflow slurry to the total mass of the slurry, and is also a dimensionless parameter. It directly reflects the concentration of the underflow slurry and can be directly used for real-time monitoring, automatic control, and production settlement of the thickener process, providing a quantitative basis for adjusting process parameters such as underflow discharge rate and reagent dosage.

[0079] It should be noted that, in terms of underflow pump control, the underflow solids mass fraction is directly related to the slurry viscosity and pipeline transport characteristics. That is, when the detected value is higher than the process target value, it indicates that the proportion of solid particles in the slurry is too high and the slurry fluidity is reduced. At this time, the underflow pump speed needs to be increased to accelerate the slurry discharge rate and avoid pipeline blockage or slurry accumulation in the thickener. When the detected value is lower than the target value, it indicates that the solid-liquid separation is insufficient. The pump speed needs to be reduced to prolong the settling time of the slurry in the thickener and improve the solid particle retention rate. By comparing the real-time detected underflow solids mass fraction with a preset target value, the pump speed can be dynamically adjusted to effectively avoid energy waste and pipeline wear caused by excessive speed, or decreased production efficiency caused by excessively low speed. In the control of flocculant dosage, the underflow solids mass fraction determines the optimal dosage of flocculant: at higher concentrations, the solid particles in the slurry are dense, requiring an increase in flocculant dosage to enhance the bridging and agglomeration effect between particles and accelerate sedimentation; at lower concentrations, excessive flocculant not only increases costs but may also lead to mother liquor contamination, requiring a reduction in dosage. Based on real-time concentration data, the flocculant dosage can be precisely matched to ensure a balance between flocculation effect and economy, avoiding low sedimentation efficiency due to insufficient reagent or subsequent process interference caused by excessive reagent, ultimately achieving dual optimization of thickener solid-liquid separation efficiency and production economy, which will not be elaborated further here.

[0080] It should be noted that the interval and threshold sizes are set for ease of comparison. The size of the threshold depends on the amount of sample data and the base number set by those skilled in the art for each set of sample data, as long as it does not affect the proportional relationship between the parameter and the quantized value. Furthermore, the above formulas are all dimensionless calculations, and the formulas are derived from software simulations using a large amount of collected data to obtain the most recent real-world results. The preset parameters in the formulas are set by those skilled in the art according to the actual situation.

[0081] The embodiments of this example have been described above. However, this example is not limited to the specific implementation methods described above. The specific implementation methods described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms based on the guidance of this example, and all of them are within the protection scope of this example.

Claims

1. A system for detecting the concentration of underflow from a thickener, characterized in that, include: The data acquisition module is used to collect the raw count rate of the thickener bottom flow and convert it into a logarithmic count rate, record operation and maintenance intervention events to divide the circulation section, and simultaneously obtain the mother liquor density and solid true density. The data calculation module is used to linearly fit the log count rate within each cycle segment according to a preset sliding window to obtain the deposition slope within the segment, and to extract the peak value of the log count rate at the beginning of each cycle and obtain the baseline drift rate by time regression. The logarithmic count rate purification module is used to calculate the deposition accumulation term and wear baseline term based on the deposition slope and baseline drift rate within the segment, and to calculate the purified logarithmic count rate accordingly. The underflow slurry density conversion module is used to convert the purified logarithmic count rate into underflow slurry density based on the densitometer calibration parameters. Densitometer calibration parameters include logarithmic intercept and density proportionality coefficient; The concentration detection module is used to convert the density of the underflow slurry into the mass fraction of the underflow solids based on the density of the mother liquor and the true density of the solids, and use this as the concentration detection result.

2. The system for detecting the concentration of underflow from a thickener according to claim 1, characterized in that, A unified sampling benchmark is set, including sampling interval and start time. The raw count rate of the underflow pipeline is continuously obtained by a radiation density meter according to the sampling benchmark, and only the raw count rate with a value greater than zero is retained. Then, the logarithmic count rate is obtained by performing natural logarithmic calculation on each. Operation and maintenance intervention events include recording cleaning and shutdown events. The continuous running period between two adjacent operation and maintenance intervention events is used as the boundary to obtain the cyclic segment. The start and end time of each cyclic segment are recorded.

3. The system for detecting the concentration of underflow from a thickener according to claim 1, characterized in that, Calculate the difference between the logarithmic count rate at each sampling time within each cyclic segment and the logarithmic count rate at each sampling time shifted forward by a preset sliding window. Then, use the ratio of this difference to the preset sliding window length as the intra-segment deposition slope at each sampling time.

4. The detection system for the underflow concentration of a thickener according to claim 1, characterized in that, The maximum value of the logarithmic count rate of the preset sliding window in each loop segment is obtained as the loop start representative value. The difference between the loop start representative value and the logarithmic count rate at the start time of each loop segment is calculated. Then, the difference between the time corresponding to the maximum value of the logarithmic count rate and the start time of each loop segment is calculated. The ratio of the two differences is used as the window drift value of the preset sliding window. The average value of the window drift values ​​of all preset sliding windows in the loop segment is used as the baseline drift rate.

5. The system for detecting the concentration of underflow from a thickener according to claim 1, characterized in that, The deposition accumulation term is obtained by multiplying the intra-segment deposition slope at any sampling time of the circulation segment by the difference between the sampling time and the start time of the circulation segment; the wear baseline term is obtained by multiplying the baseline drift rate of the circulation segment by the difference between the end time and the start time of the circulation segment.

6. The system for detecting the concentration of underflow from a thickener according to claim 1, characterized in that, The purified logarithmic count rate is obtained by subtracting the deposition accumulation term and wear baseline term at the corresponding time from the logarithmic count rate at any sampling time in the cyclic section.

7. The detection system for the underflow concentration of a thickener according to claim 1, characterized in that, The difference between the logarithmic intercept and the logarithmic count rate after purification at each sampling time is calculated. Then, the ratio between this difference and the density proportionality coefficient is calculated to obtain the underflow slurry density at that sampling time. The logarithmic intercept and the density proportionality coefficient are obtained by the two-point calibration method.

8. A detection system for the concentration of underflow from a thickener according to claim 7, characterized in that, The two-point calibration method includes the following steps: Step S201: Select two stable operating conditions with known densities and sufficiently large differences; The first working condition is the mother liquor working condition, and the corresponding known density is the mother liquor density. The second working condition is the high solids content or standard solution working condition, and the corresponding known density is the high solids content or standard solution density, and the high solids content or standard solution density is greater than the mother liquor density. Step S202: Calculate the average value of the purification log count rate for the two stable operating conditions; Within the stable time window of the first operating condition, the average value of the logarithmic count rate after purification is taken and recorded as the average value of the first purification logarithmic count rate. Within the stable time window of the second operating condition, the average value of the logarithmic count rate after purification is taken and recorded as the average value of the second purification logarithmic count rate. The length of the stable time window is a custom parameter, which is a positive integer multiple of the sampling interval, and at the same time satisfies the condition that the fluctuation of the logarithmic count rate after purification within the time window does not exceed 2% of its average value; Step S203: Calculate the density proportionality coefficient based on the average value of the purification log count rate under two stable operating conditions. The first difference is obtained by subtracting the average value of the second logarithmic count rate from the average value of the first purification logarithmic count rate. The second difference is obtained by subtracting the known density of the first working condition from the known density of the second working condition. The density ratio coefficient is obtained by dividing the first difference by the second difference. Step S204: Calculate the logarithmic intercept based on the density proportionality coefficient; Multiply the density proportionality coefficient by the known density of the first working condition, and then add it to the average value of the first purification logarithmic count rate to obtain the logarithmic intercept.

9. A detection system for the concentration of underflow from a thickener according to claim 8, characterized in that, The third difference is obtained by subtracting the density ratio coefficient from the logarithmic intercept and multiplying it by the known density of the second working condition. The absolute value of the difference between the third difference and the average value of the second purification logarithmic count rate is calculated. If the absolute value is less than or equal to the residual threshold, the logarithmic intercept and density ratio coefficient are deemed valid. Otherwise, the process returns to step S201 and is re-executed. The residual threshold is a user-defined parameter.

10. A detection system for the concentration of underflow from a thickener according to claim 1, characterized in that, First, calculate the difference between the density of the underflow slurry and the density of the mother liquor at each sampling time. Then, calculate the difference between the true density of the solids and the density of the mother liquor. The ratio of the two differences is taken as the solid volume fraction at that sampling time. Then, multiply the solid volume fraction at that sampling time by the true density of the solids and divide it by the density of the underflow slurry to obtain the underflow solid mass fraction at that sampling time.

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