A detection system for thickener underflow concentration

Abstract

The present application relates to tailings disposal technical field, disclose a kind of for thickener underflow concentration detection system, comprising: data acquisition module, logarithmic counting rate is obtained by calculation, and mother liquor density and solid true density are synchronously obtained;Data calculation module, obtains the deposition slope in section and baseline drift rate by calculation;Logarithmic counting rate purification module, deposition cumulative term and wear baseline term are obtained according to the deposition slope in section and baseline drift rate by calculation, and logarithmic counting rate after purification is obtained according to this;Underflow slurry density conversion module, logarithmic counting rate after purification is converted into underflow slurry density;Concentration detection module, according to mother liquor density and solid true density, underflow slurry density is converted into underflow solid mass fraction.The present application is through systematic signal processing and data conversion mechanism, effectively eliminate the interference of pipe wall wear, deposition in pipe and other geometric factors to detection signal, greatly improve the accuracy and reliability of thickener underflow concentration detection.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of tailings disposal, more particularly, it relates to a detection system for the underflow concentration of a thickener. BACKGROUND

[0002] In the industries of ore dressing and metallurgy, the thickener is a core equipment for realizing the solid-liquid separation of ore slurry, and the underflow concentration thereof directly determines the efficiency of subsequent filtering, drying and other processes and the quality of final products, so the accurate detection of the underflow concentration is very important. At present, the mainstream in the industry adopts a radiation density meter for detection, and the principle thereof is to utilize the attenuation characteristics of gamma rays when penetrating the ore slurry, to detect the original count rate after penetration, to convert the original count rate into a logarithmic count rate, to calculate the slurry density by combining the calibration parameters, and to convert the slurry density into the underflow concentration.

[0003] However, in actual operation, this detection method is seriously interfered by the geometric changes of the pipeline, and the technical problems are as follows: on the one hand, the solid particles in the ore slurry will continuously deposit on the inner wall of the underflow pipeline, and the thickening of the deposition layer will enhance the attenuation effect of the gamma rays, resulting in a gradual decrease in the logarithmic count rate with the running time. This decrease is not caused by the increase in the slurry concentration, but by the physical blockage of the deposition layer; on the other hand, the pipeline will be abraded for a long time under the scouring of the ore slurry, the pipe wall will become thin, the attenuation of the gamma rays will be weakened, and the baseline of the logarithmic count rate will slowly drift upward. This drift has nothing to do with the change in the slurry concentration.

[0004] The existing detection method does not design an effective stripping mechanism for the above-mentioned geometric factors, directly uses the original logarithmic count rate containing interference for concentration conversion, and often misjudges the decrease in the count rate caused by deposition as an increase in the concentration, and misjudges the baseline drift caused by abrasion as a decrease in the concentration. In addition, the cleaning or shutdown operation in operation will remove the deposition layer, the count rate will suddenly reset and rise, further disrupting the signal rules, the simple calibration cannot eliminate the accumulated error, and finally the detection result will be significantly deviated, seriously affecting the accurate regulation of process parameters such as the underflow pump speed and the flocculant dosage, and reducing the production stability and efficiency. SUMMARY

[0005] The present application provides a detection system for the underflow concentration of a thickener, which solves the technical problems in the background art.

[0006] The present application provides a detection system for the underflow concentration of a thickener, which includes:

[0007] A data acquisition module is configured to acquire the original count rate of the underflow of the thickener and convert it into a logarithmic count rate, record the operation and maintenance intervention events to divide the cycle sections, and synchronously acquire the mother liquor density and the solid true density;

[0008] a data calculation module configured to linearly fit the logarithmic count rate in each cycle section according to a preset sliding window to obtain a deposition slope in the section, and extract a peak value of the logarithmic count rate at the start of each cycle and regress the peak value according to time to obtain a baseline drift rate;

[0009] a logarithmic count rate purification module configured to calculate a deposition accumulation term and an abrasion baseline term according to the deposition slope in the section and the baseline drift rate, and calculate a purified logarithmic count rate according to the deposition accumulation term and the abrasion baseline term;

[0010] a bottom flow slurry density conversion module configured to convert the purified logarithmic count rate into a bottom flow slurry density according to a densimeter calibration parameter;

[0011] the densimeter calibration parameter comprises a logarithmic intercept and a density proportionality coefficient;

[0012] a concentration detection module configured to convert the bottom flow slurry density into a bottom flow solid mass fraction as a concentration detection result according to a mother liquor density and a solid true density.

[0013] Further, a unified sampling reference is set, including a sampling interval and a start time, the original count rate of the bottom flow pipeline is continuously obtained by the radiation densimeter according to the sampling reference, and only the original count rate with a value greater than zero is reserved, and then a natural logarithm operation is performed to obtain a logarithmic count rate; the operation and maintenance intervention events include recording cleaning and shutdown events, and a continuous operation period between adjacent two operation and maintenance intervention events is taken as a boundary to divide to obtain a cycle section, and the start and end time of each cycle section is recorded.

[0014] Further, a difference value between the logarithmic count rate at each sampling time and the logarithmic count rate of a preset sliding window forwardly moved from the sampling time by one preset sliding window in each cycle section is calculated, and a ratio of the difference value to the length of the preset sliding window is taken as a deposition slope in the section at each sampling time.

[0015] Further, a maximum value of the logarithmic count rate of the preset sliding window in each cycle section is taken as a cycle start representative value, a difference value between the cycle start representative value and the logarithmic count rate at the start time of each cycle section is calculated, and a difference value between the time corresponding to the maximum value of the logarithmic count rate and the start time of each cycle section is calculated, a ratio of the two difference values is taken as a window drift value of the preset sliding window, and an average value of the window drift values of all the preset sliding windows in the cycle section is taken as a baseline drift rate.

[0016] Further, the deposition accumulation term is obtained by multiplying the deposition slope in the section at any sampling time of the cycle section by a difference value between the sampling time and the start time of the cycle section, and the abrasion baseline term is obtained by multiplying the baseline drift rate of the cycle section by a difference value between the end time of the cycle section and the start time of the cycle section.

[0017] Further, the purified log count rate is obtained by subtracting the deposition accumulation term and the attrition baseline term at the corresponding time point from the log count rate at any sampling time point of the circulation section.

[0018] Further, the difference between the log intercept and the purified log count rate at each sampling time point is calculated, and the ratio between the difference and the density proportionality coefficient is calculated to obtain the underflow slurry density at the sampling time point, wherein the log intercept and the density proportionality coefficient are obtained by two-point calibration.

[0019] Further, the two-point calibration method comprises the following steps:

[0020] Step S201, selecting two stable working conditions with known densities and a large enough difference;

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

[0022] Step S202, calculating the average values of the purified log count rates of the two stable working conditions;

[0023] In the stable time window of the first working condition, the average value of the purified log count rate is taken as the first purified log count rate average value;

[0024] In the stable time window of the second working condition, the average value of the purified log count rate is taken as the second purified log count rate average value;

[0025] The length of the stable time window is a positive integer multiple of the sampling interval, and simultaneously satisfies that the fluctuation amplitude of the purified log count rate in the time window is not more than 2% of the average value;

[0026] Step S203, calculating the density proportionality coefficient according to the average values of the purified log count rates of the two stable working conditions;

[0027] The first difference value is obtained by subtracting the second purified log count rate average value from the first purified log count rate average value. The second difference value is obtained by subtracting the known density of the first working condition from the known density of the second working condition. The density proportionality coefficient is obtained by dividing the first difference value by the second difference value;

[0028] Step S204, calculating the log intercept according to the density proportionality coefficient;

[0029] The log intercept is obtained by multiplying the density proportionality coefficient by the known density of the first working condition and then adding the first purified log count rate average value.

[0030] Further, a third difference value is obtained by subtracting the known density of the second working condition from the logarithmic intercept multiplied by the density proportional coefficient, and the absolute value of the difference between the third difference value and the average value of the second net count rate is calculated. If the absolute value is less than or equal to the residual threshold, it is determined that the logarithmic intercept and the density proportional coefficient are valid, otherwise, return to step S201 to re-execute, wherein the residual threshold is a self-defined parameter.

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

[0032] The beneficial effects of the present application are as follows: through the systematic signal processing and data conversion mechanism, the present application effectively eliminates the interference of geometric factors such as pipe wall wear and pipe deposition on the detection signal, greatly improves the accuracy and reliability of the thickener underflow concentration detection; the original count rate of the underflow is collected first and converted into a logarithmic count rate, the circulating section is divided by recording maintenance events such as cleaning and shutdown, and the mother liquor density and solid true density are obtained synchronously; then the deposition accumulation term and the wear baseline term are deducted according to the in-circulating section deposition slope and baseline drift rate, to obtain the net logarithmic count rate reflecting only the slurry characteristics; the accurate underflow slurry density is converted by combining the logarithmic intercept and the density proportional coefficient calibrated by two-point calibration, and the underflow solid mass fraction is converted, which can be directly used for precise control of the underflow pump operation, flocculant addition and other process links, and the circulating section division and parameter verification mechanism ensure that the detection process is traceable and convenient to maintain, significantly improving the production stability and efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0033] Fig. 1 is a schematic diagram of a detection system for the underflow concentration of a thickener according to the present application;

[0034] Fig. 2 is a flowchart of the two-point calibration method according to the present application.

[0035] In the figure: 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 DESCRIPTION

[0036] The subject matter described herein will now be discussed with reference to example implementations. It should be understood that the implementations discussed are merely for illustration and that the elements of the discussions can be modified, supplemented, or omitted in different examples. Additionally, features described in relation to some examples can also be combined in other examples.

[0037] It should be noted that the technical terms or scientific terms used in one or more embodiments of the present application should be understood as the general meaning understood by a person having ordinary skill in the art to which the present application pertains, unless otherwise defined. The terms "first", "second", and the like used in one or more embodiments of the present application do not represent any order, number, or importance, but are used to distinguish different components. The terms "include" or "contain" and the like mean that the elements or objects appearing before the terms encompass the elements or objects listed after the terms and their equivalents, and do not exclude other elements or objects. The terms "connected" or "linked" and the like do not mean only physical or mechanical connections, but can include electrical connections, whether direct or indirect. The terms "upper", "lower", "left", "right", and the like are used only to indicate relative positional relationships, and when the absolute positions of the described objects are changed, the relative positional relationships can also be changed accordingly.

[0038] As shown in Figs. 1-2 A detection system for thickener underflow concentration, comprising:

[0039] A data acquisition module 101 for acquiring raw count rate of thickener underflow and converting it into logarithmic count rate, recording operation and maintenance intervention events to divide cycle sections, and synchronously acquiring mother liquor density and solid true density;

[0040] A data calculation module 102 for linearly fitting logarithmic count rate in each cycle section according to a preset sliding window to obtain a section deposition slope, and extracting a logarithmic count rate peak at the start of each cycle and obtaining a baseline drift rate by time regression;

[0041] A logarithmic count rate purification module 103 for calculating a deposition accumulation item and an abrasion baseline item according to the section deposition slope and the baseline drift rate, and calculating a purified logarithmic count rate accordingly;

[0042] An underflow slurry density conversion module 104 for converting the purified logarithmic count rate into underflow slurry density according to density meter calibration parameters;

[0043] The density meter calibration parameters include a logarithmic intercept and a density proportionality coefficient;

[0044] A concentration detection module 105 is configured to convert the underflow slurry density into the underflow solid mass fraction according to the mother liquor density and the solid true density as the concentration detection result.

[0045] In one embodiment of the present application, a unified sampling reference including a sampling interval and a starting time is set, the original count rate of the underflow pipeline is continuously acquired by the radiation density meter according to the sampling reference, and only the original count rate with a value greater than zero is retained, and then the natural logarithm operation is performed to obtain the logarithmic count rate; the operation and maintenance intervention events include recording cleaning and shutdown events, and the cycle section is divided by taking the continuous operation period between the adjacent two operation and maintenance intervention events as the boundary, and the starting and ending time of each cycle section is recorded.

[0046] It should be noted that the thickener underflow original count rate represents the particle count per second after the gamma rays detected by the radiation density meter on the thickener underflow pipeline penetrate the ore slurry, and the logarithmic count rate is the conversion of the exponential decay relationship of the gamma rays penetrating the ore slurry into a linear relationship, which facilitates the subsequent separation of the influence of geometric interference factors such as pipe wall wear and pipe deposition from the change of the ore slurry concentration; the mother liquor density represents the density of the liquid medium in the thickener underflow ore slurry, i.e. the density of the pure liquid phase not containing solid particles, which is measured by laboratory personnel according to the industry standard detection method, for example, the density bottle method or the densimeter method is used to detect the underflow mother liquor sample; the solid true density represents the true density of the solid particles in the thickener underflow ore slurry, i.e. the density of the pure material excluding the internal pores of the solid particles, which reflects the material properties of the solid itself and can be obtained by laboratory detection, and the commonly used methods include the specific gravity bottle method or the gas displacement method, i.e. the true density of the solid particle sample in the underflow is measured after purification treatment; the operation and maintenance intervention events mainly refer to the cleaning or equipment shutdown operations of the thickener underflow pipeline, which directly cause the deposition layer in the pipe to be removed, so that the logarithmic count rate appears a transient reset rise, and the cycle section is divided accordingly, which facilitates focusing on the growth law of the pipe deposition in the cycle section, i.e. the complete process of the deposition layer gradually forming after cleaning and shutdown, and avoids the detection and control deviation caused by interference misjudgment.

[0047] In one embodiment of the present application, the difference between the logarithmic count rate at each sampling time and the logarithmic count rate of the preset sliding window moved forward from the sampling time is calculated, and the ratio of the difference value to the length of the preset sliding window is taken as the in-section deposition slope at the 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 in the pipe enhances the degree of attenuation of gamma rays, the logarithmic count rate shows a downward trend, therefore, the deposition slope in the section can directly quantify the rate of influence of the gradual thickening of the deposition layer on the logarithmic count rate; since the wear of the pipe wall can thin the wall thickness, the attenuation of the gamma rays is reduced when penetrating, and the logarithmic count rate slowly rises over time, therefore, the baseline drift rate can directly quantify the rate of influence of the long-term wear of the pipe wall on the baseline of the logarithmic count rate; the length of the preset sliding window is a positive integer multiple of the sampling interval, but cannot exceed the length of the circulating section, preferably, the length of the preset sliding window is set to the upward rounding of 1 / 10 of the length of the circulating section, and the step of the preset sliding window is equal to the length of the preset sliding window, that is, non-overlapping sliding, the non-overlapping window can ensure the independence of each calculation interval, that is, the deposition slope in the section at each sampling time corresponds to a non-repeated time window, ensuring the definiteness of the slope calculation and the consistency of the results.

[0054] In an embodiment of the present application, the deposition accumulation item is obtained by multiplying the deposition slope in the section at any sampling time of the circulating section by the difference between the sampling time and the starting time of the circulating section; the wear baseline item is obtained by multiplying the baseline drift rate of the circulating section by the difference between the termination time of the circulating section and the starting time of the circulating section.

[0055] In an embodiment of the present application, the purified logarithmic count rate is obtained by subtracting the deposition accumulation item and the wear baseline item at the corresponding time from the logarithmic count rate at any sampling time of the circulating section.

[0056] It should be noted that the deposition accumulation item is used to quantify the total amount of the decrease in the logarithmic count rate caused by the thickening of the deposition layer in the pipe wall over time, as the deposition interference amount that needs to be stripped from the observed logarithmic count rate in the subsequent process, to avoid misjudging the decrease in the logarithmic count rate caused by the deposition as a change in the slurry density; the wear baseline item is used to quantify the total amount of the slow rise in the logarithmic count rate baseline caused by the wear of the pipe wall, as the wear interference amount that needs to be stripped from the observed logarithmic count rate in the subsequent process, to avoid misjudging the rise in the logarithmic count rate caused by the wear as a change in the slurry density; the purified logarithmic count rate is used to strip the interference of the two types of geometric factors, i.e., the wear of the pipe wall and the deposition in the pipe, on the logarithmic count rate, so that the obtained purified logarithmic count rate only reflects the information of the slurry itself factors (including the underflow density, the mother liquor density, the solid content, etc.), providing accurate input data for the subsequent conversion of the logarithmic count rate into the underflow concentration.

[0057] In an embodiment of the present application, the difference between the logarithmic intercept and the purified logarithmic count rate 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 the sampling time, wherein the logarithmic intercept and the density proportionality coefficient are obtained by two-point calibration.

[0058] It should be noted that the underflow pulp density represents the mass per unit volume of the pulp at the underflow outlet of the thickener, which contains solid particles and mother liquor, and the value directly reflects the mixing density of the solid particles and the mother liquor in the underflow pulp, and is a core parameter for subsequent conversion of the underflow solid mass fraction.

[0059] In one embodiment of the present application, as shown in FIG. 1, a two-point calibration method includes the following steps: Fig. 2

[0060] Step S201, selecting two stable working conditions with known density and large enough difference;

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

[0062] Step S202, calculating the average value of the purification log count rate of the two stable working conditions;

[0063] In the stable time window of the first working condition, the average value of the purified log count rate is taken as the first purified log count rate average value;

[0064] In the stable time window of the second working condition, the average value of the purified log count rate is taken as the second purified log count rate average value;

[0065] The length of the stable time window is a positive integer multiple of the sampling interval, and at the same time, the fluctuation amplitude of the purified log count rate in the time window does not exceed 2% of the average value, and preferably, the length of the stable time window is set to 60 seconds;

[0066] Step S203, calculating the density proportionality coefficient according to the average value of the purified log count rate of the two stable working conditions;

[0067] The first purified log count rate average value is subtracted from the second purified log count rate average value to obtain a first difference value, and the known density of the second working condition is subtracted from the known density of the first working condition to obtain a second difference value. The density proportionality coefficient is obtained by dividing the first difference value by the second difference value;

[0068] Step S204, calculating the log intercept according to the density proportionality coefficient;

[0069] The density proportionality coefficient is multiplied by the known density of the first working condition, and then added to the first purified log count rate average value to obtain the log intercept.

[0070] ​In one embodiment of the present application, a third difference value is obtained by subtracting the known density of the second working condition from the logarithmic intercept multiplied by the density proportional coefficient, the absolute value of the difference between the third difference value and the average value of the second purified logarithmic count rate is calculated, and it is determined that the logarithmic intercept and the density proportional coefficient are valid if the absolute value is less than or equal to a residual threshold value, otherwise, step S201 is returned to be executed again, wherein the residual threshold value is a self-defined parameter, and preferably, the residual threshold value is set to 5% of the absolute value.

[0071] It should be noted that when the gamma rays penetrate the slurry, the degree of attenuation is exponentially related to the density of the slurry, and after logarithmic conversion, the purified logarithmic count rate is linearly related to the density of the slurry; by selecting two stable working conditions with known density and large enough difference, the average value of the purified logarithmic count rate in the stable time window of each working condition is obtained, and by using the above linear relationship, the intercept (i.e. the logarithmic intercept) and the slope (i.e. the density proportional coefficient) of the linear relationship are calculated by using the two known density values and the corresponding two average values of the purified logarithmic count rate, thereby establishing a quantitative conversion relationship between the purified logarithmic count rate and the density of the underflow slurry.

[0072] It should be noted that the logarithmic intercept represents the theoretical logarithmic count value when the density of the underflow slurry is zero in the linear relationship between the purified logarithmic count rate and the density of the underflow slurry, which comprehensively reflects the influence of fixed factors such as gamma ray source intensity, detector gain, and geometric structure of the ray penetration path on the logarithmic count rate; the density proportional coefficient represents the sensitivity coefficient of the change of the logarithmic count rate with the density of the underflow slurry in the linear relationship between the purified logarithmic count rate and the density of the underflow slurry, i.e. the change amount of the purified logarithmic count rate caused by the unit change of the density of the underflow slurry, which is greater than zero, ensuring that the linear conversion between the purified logarithmic count rate and the density of the underflow slurry has a clear quantitative corresponding relationship, which is used to accurately map the purified logarithmic count rate to the density of the underflow slurry.

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

[0074] Specifically, the calculation formula of the solid mass fraction of the underflow at the tth sampling time is as follows:

[0075] , wherein represents the density of the underflow slurry at the tth sampling time, represents the true density of the solid;

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

[0077] represents the mother liquor density.

[0078] It should be noted that the solid volume fraction represents the proportion of the volume of the solid particles in the thickener underflow slurry to the total volume of the slurry, which is a dimensionless parameter. The underflow solid mass fraction represents the proportion of the mass of the solid particles in the thickener underflow slurry to the total mass of the slurry, which is 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 quantitative basis for adjusting the underflow discharge rate, reagent addition amount and other process parameters.

[0079] It should be noted that in terms of underflow pump regulation, the underflow solid mass fraction is directly related to the slurry viscosity and pipeline transportation characteristics. When the detection value is higher than the process target value, it indicates that the proportion of solid particles in the slurry is too high, and the flowability of the slurry decreases. At this time, the speed of the underflow pump needs to be increased to speed up the discharge of the slurry and avoid pipeline blockage or slurry accumulation in the thickener. When the detection value is lower than the target value, it indicates that the solid-liquid separation is insufficient, and 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 solid mass fraction with the preset target value and dynamically adjusting the pump speed, the problems of energy waste and pipeline wear caused by excessive speed, or production efficiency reduction caused by low speed can be effectively avoided. In the flocculant addition regulation, the underflow solid mass fraction determines the optimal amount of flocculant: when the concentration is high, the solid particles in the slurry are dense, and the amount of flocculant needs to be increased to enhance the bridging and agglomeration effect between particles and accelerate settling; when the concentration is low, excessive flocculant not only increases the cost, but also may cause mother liquor pollution, and the addition amount needs to be reduced. Based on the real-time concentration data, the amount of flocculant can be accurately matched to ensure the balance between flocculation effect and economy, avoid low settling efficiency caused by insufficient reagent, or subsequent process interference caused by excessive reagent, and finally realize the dual optimization of thickener solid-liquid separation efficiency and production economy. Details are not described here.

[0080] It should be noted that the interval and threshold size are set for easy comparison. The size of the threshold depends on the number of sample data and the base number set by the person skilled in the art for each group of sample data, as long as it does not affect the proportional relationship between the parameters and the quantized values. And the above formulas are all dimensionless calculations of the values. The formula is obtained by collecting a large amount of data to simulate the most real situation. The preset parameters in the formula are set by the person skilled in the art according to the actual situation.

[0081] ​​The above describes the embodiments of the present embodiment, but the present embodiment is not limited to the above-described specific embodiments, and the above-described specific embodiments are only illustrative but not restrictive, and those skilled in the art can make many forms under the inspiration of the present embodiment, which all belong to the protection of the present embodiment.

Claims

1. A system for detecting the underflow concentration of a thickener, characterized by, The method comprises the following steps: A data acquisition module is used to acquire the raw count rate of the underflow of the thickener and convert it into a logarithmic count rate, record operation and maintenance intervention events to divide cycle sections, and synchronously acquire the mother liquor density and the true density of solids; A data calculation module is used to linearly fit the logarithmic count rate in each cycle section according to a preset sliding window to obtain a section deposition slope, extract a logarithmic count rate peak at the start of each cycle, and obtain a baseline drift rate by time regression; A logarithmic count rate purification module is used to calculate a deposition accumulation term and an abrasion baseline term according to the section deposition slope and the baseline drift rate, and calculate a purified logarithmic count rate according to the same; An underflow slurry density conversion module is used to convert the purified logarithmic count rate into the underflow slurry density according to the density gauge calibration parameters; The density gauge calibration parameters include a logarithmic intercept and a density proportionality coefficient; A concentration detection module is used to convert the underflow slurry density into the underflow solid mass fraction as a concentration detection result according to the mother liquor density and the true density of solids; A uniform sampling reference is set, including a sampling interval and a start time, the raw count rate of the underflow pipeline is continuously acquired by the radiation type density gauge according to the sampling reference, only the raw count rate with a value greater than zero is retained, and then natural logarithm operation is performed to obtain the logarithmic count rate; the operation and maintenance intervention events include recording cleaning and shutdown events, and cycle sections are divided by taking the continuous operation period between adjacent two operation and maintenance intervention events as a boundary to obtain cycle sections, and the start and end times of each cycle section are recorded; The deposition accumulation term is obtained by multiplying the section deposition slope at any sampling time of the cycle section by the difference between the sampling time and the start time of the cycle section; the abrasion baseline term is obtained by multiplying the baseline drift rate of the cycle section by the difference between the end time of the cycle section and the start time of the cycle section; The purified logarithmic count rate is obtained by subtracting the deposition accumulation term and the abrasion baseline term at the corresponding time from the logarithmic count rate at any sampling time of the cycle section; The difference between the logarithmic intercept and the purified logarithmic count rate 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 the sampling time, wherein the logarithmic intercept and the density proportionality coefficient are obtained by a two-point calibration method.

2. A system for detecting underflow concentration of a thickener according to claim 1, characterized in that, The difference between the logarithmic count rate at each sampling time in each cycle section and the logarithmic count rate at each sampling time moving forward by a preset sliding window is calculated, and the ratio between the difference and the length of the preset sliding window is taken as the section deposition slope at each sampling time.

3. A system for detecting underflow concentration of a thickener as claimed in claim 1 wherein, The two-point calibration method comprises the following steps: Step S201, two stable working conditions with known densities and a large enough difference are selected; The first working condition is a mother liquor working condition, and the known density corresponding thereto is the mother liquor density; the second working condition is a high solid content or standard solution working condition, and the known density corresponding thereto is the high solid content or standard solution density, and the high solid content or standard solution density is greater than the mother liquor density; Step S202, the average value of the purified logarithmic count rate of the two stable working conditions is calculated; In the stable time window of the first working condition, the average value of the purified logarithmic count rate is taken as a first purified logarithmic count rate average value; Step S203, the density proportionality coefficient is calculated by the following formula: In the stable time window of the second working condition, the average value of the purified logarithmic count rate is taken as the second purified logarithmic count rate average value; The length of the stable time window is a positive integer multiple of the sampling interval, and the fluctuation amplitude of the purified logarithmic count rate in the time window is not more than 2% of the average value; Step S203, the density proportionality coefficient is calculated according to the purified logarithmic count rate average values of the two stable working conditions; The first difference value is obtained by subtracting the second purified logarithmic count rate average value from the first purified logarithmic count rate average value, the second difference value is obtained by subtracting the known density of the first working condition from the known density of the second working condition, and the density proportionality coefficient is obtained by dividing the first difference value by the second difference value; Step S204, the logarithmic intercept is calculated according to the density proportionality coefficient; The logarithmic intercept is obtained by multiplying the density proportionality coefficient by the known density of the first working condition and adding the first purified logarithmic count rate average value.

4. A system for detecting underflow concentration of a thickener according to claim 3, characterized in that, The third difference value is obtained by subtracting the density proportionality coefficient multiplied by the known density of the second working condition from the logarithmic intercept, the absolute value of the difference between the third difference value and the second purified logarithmic count rate average value is calculated, and it is judged whether the absolute value is less than or equal to the residual threshold value. If yes, it is determined that the logarithmic intercept and the density proportionality coefficient are valid, otherwise, return to step S201 to execute again, wherein the residual threshold value is a self-defined parameter.

5. A system for detecting underflow concentration of a thickener as claimed in claim 1 wherein, First, the difference between the underflow slurry density and the mother liquor density at each sampling time is calculated, then the difference between the solid true density and the mother liquor density is calculated, and the ratio of the two difference values is taken as the solid volume fraction at the sampling time. Then, the solid volume fraction at the sampling time is multiplied by the solid true density, and then divided by the underflow slurry density to obtain the underflow solid mass fraction at the sampling time.

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