CN109759316B - Screening instrument and screening method for detecting grading characteristic reliability of granular material - Google Patents
Screening instrument and screening method for detecting grading characteristic reliability of granular material Download PDFInfo
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Abstract
The invention discloses a screening instrument and a screening method for detecting the grading characteristic reliability of a granular material. The screening instrument comprises a base plate, an elastic vibration module, a stand column and a frame beam which are arranged on the base plate, a vibration table arranged on the elastic vibration module, and a screening box arranged on the vibration table; a feeding box is fixedly arranged at the upper part of the frame beam, and an outlet of the feeding box extends into the sieve box; the upright post is provided with a bearing platform, the bearing platform is provided with a plurality of storage boxes, and the discharge port of the screen box is aligned with the feed port of the storage boxes; the screen box is divided into a plurality of grids from bottom to top by a plurality of horizontally arranged screen plates, wherein the screen pore diameter of the screen plate of the upper layer is larger than that of the screen pore diameter of the screen plate of the lower layer, and a storage box is correspondingly arranged at the discharge port of each grid; the shaking table unilateral slope sets up, and wherein the feeding case is located the higher one side of shaking table, and the storage case is located the lower one side of shaking table. The screening instrument is quick and convenient to use and reliable in precision.
Description
Technical Field
The invention relates to a sieving instrument and a sieving method for detecting the grading characteristic reliability of a granular material, in particular to a sieving instrument capable of realizing intelligent tracking analysis of the granularity of a granular material sample and the distribution characteristic reliability thereof.
Background
Particulate materials are widely found in nature, daily life and in the fields of production and technology, for example: the building materials such as sand stone, soil, grain, sugar, salt and medicine in daily life in nature, and various ores, coal, lime, fly ash and the like in the production and technical fields all belong to granular substances.
The bulk properties of the particulate material mainly include the size, shape, surface area of the particles, and the magnetic, electrical, optical properties of the particles. The size of the particles is an important basis for classifying the particle materials, and has a significant influence on various physical mechanical and chemical reaction characteristics of the particle materials. The main parameters for measuring and analyzing the particle size are the particle size and the distribution characteristics. For a certain particle material, the particle size and the particle grading characteristics thereof largely determine the properties and efficiency of the particle processing technology, and are the basic basis for selecting and evaluating the preparation method, the technology and the process control. Taking various soil particle materials encountered in civil engineering major as an example, the particle grading characteristic is a main index for classifying various soils such as sand, broken stone, block stone and the like, determines the physical mechanics and engineering properties of the soils, and in the construction activities of housing construction, railways, large earth and rockfill dams, airports and the like, firstly, the particle grading condition of the soil body on site needs to be determined, and then the soil body is classified according to the grading characteristic and other related indexes so as to further research the mechanics and engineering characteristics such as the strength, deformation, bearing capacity and the like of the soil. Therefore, when the number of surface pairs is huge, the particle size distribution range is wide and irregular, how to accurately, quickly and efficiently obtain the overall particle size and the particle grading distribution characteristic of the particles becomes an important problem and a technical problem in front of every scientific research and engineering technician.
Currently, the conventional method for determining the particle size and distribution characteristics of the particulate material is to randomly extract a plurality of samples from the particle population, obtain the particle size and particle grading characteristics through a screening test, and further represent the particle size grading characteristics of the particle population by using the particle size and distribution characteristics of the samples through an averaging method. In this process, it is necessary to ensure that the selected sample has sufficient representativeness, and therefore, the sampling amount, sampling method, etc. of the sample have an important influence on the reliability of the test result. For example, when the total number of particles is large and the particle size distribution range is wide, if the sampling amount is insufficient, the particle size and the distribution characteristics thereof determined after passing the screening test cannot represent the particle grading characteristics of the total particles; when the sampling amount is too much, the engineering amount is gradually larger, so that the materials in the screening box are too much, the screening efficiency is reduced, and a large amount of resources such as manpower and material resources are wasted in the screening test process.
In summary, in order to determine the overall particle size distribution of the particulate material, how many quality samples are required to be screened to objectively and accurately reflect the overall particle size distribution characteristics, national and industrial regulations have not been clearly described, and related scientific research is rarely reported.
Disclosure of Invention
The invention aims to provide a screening instrument and a screening method for detecting the grading characteristic reliability of a granular material, the screening instrument is quick and convenient to use and reliable in precision, and particularly has wide size distribution range, high grading complexity and huge total number of granules in the aspect of the granular material frequently involved in the professional fields of related subjects such as chemical industry, mining, civil engineering, pharmacy, and the like.
In order to achieve the purpose, the invention adopts the technical scheme that:
a sieve separator for detecting the reliability of grading characteristics of granular materials is structurally characterized by comprising a base plate, an elastic vibration module, a stand column, a frame beam, a vibration table and a sieve box, wherein the elastic vibration module, the stand column and the frame beam are arranged on the base plate;
a feeding box is fixedly arranged at the upper part of the frame beam, and an outlet of the feeding box extends into the sieve box; the upright post is provided with a bearing platform, the bearing platform is provided with a plurality of storage boxes, and the discharge port of the screen box is aligned with the feed port of the storage boxes;
the screen box is divided into a plurality of grids from bottom to top by a plurality of horizontally arranged screen plates, wherein the screen pore diameter of the screen plate of the upper layer is larger than that of the screen pore diameter of the screen plate of the lower layer, and a storage box is correspondingly arranged at the discharge port of each grid;
the shaking table unilateral slope sets up, and wherein the feeding case is located the higher one side of shaking table, and the storage case is located the lower one side of shaking table.
According to the embodiment of the invention, the invention can be further optimized, and the following is the technical scheme formed after optimization:
preferably, the elastic vibration module comprises a plurality of piers arranged on the base plate, compression springs arranged between the tops of the piers and the vibration table, and a vibration motor arranged on the vibration table; preferably, the vibration motor is a centrifugal vibration motor; preferably, rubber cushion layers are arranged between the compression spring and the vibration table and between the compression spring and the pier stud.
In order to facilitate control of the vibration frequency and the vibration amplitude, the vibration motor is electrically connected with the frequency converter.
Preferably, two adjacent grids of the screen box are locked together by a fixing lock, and one grid at the lowest layer is fixed on the vibrating table by a fastening clamp; preferably, the side wall of each lattice is provided with an observation window; preferably, the top of the sieve box is provided with a dust cover.
Preferably, the inclination angle of the vibration table is 0-5 degrees relative to the horizontal plane.
Furthermore, the invention also comprises a computer, a programmable logic controller, an operation controller and a data acquisition instrument; a bearing sensor is arranged between the bearing platform and the material storage box; the computer is communicated with an operation controller, the operation controller is communicated with a programmable logic controller, the programmable logic controller is connected with a data acquisition instrument, and the data acquisition instrument is electrically connected with the bearing sensor.
In order to facilitate the height adjustment of the frame beams and/or the uprights, preferably the frame beams are height-adjustable telescopic beams and/or the uprights are height-adjustable telescopic columns.
Based on the same inventive concept, the invention also provides a method for screening the granular materials by using the screening instrument for detecting the grading characteristic reliability of the granular materials, which comprises the following steps:
s1, determining the average density of the whole particle material to be measured, and fixing the screen box on a vibration table;
s2, weighing sample materials and placing the sample materials in a feeding box, starting an elastic vibration module to enable the sample materials to flow into a screen box under the action of self weight and move towards a discharge port until the sample materials flow into a material storage box;
s3, stopping the elastic vibration module after all the sample materials flow into the corresponding storage box, and weighing the weight of the particles collected in the storage box.
Further, the method also comprises a step S4 of inputting the density of the particles, the mass of each layer of particles and the aperture size signals collected in the step S3 from the input port of the programmable logic controller, and obtaining the number n of the particles in each particle group interval through calculationjMedian particle diameter of sample
And particle size distribution characteristic PSD1；
Calculating the median particle diameter obtained in the screening test by a programmable logic controller
And
make a comparison if
It indicates that the weighed sample mass meets the precision requirement, that is, the particle grading characteristic obtained by the test at this time can represent the particle distribution of the particle population, if
The quality of the weighed sample is insufficient, and the particle grading characteristics obtained by the screening test cannot represent the particle distribution condition of the particle population, and the accuracy is beyond the set accuracy range.
Repeating the steps S1-S4 according to the sample mass to be weighed determined by the last screening test until the median value of the particle sample of the (k + 1) th screening test after the computation of the programmable logic controllerParticle size of
In the range of-0.5 mm to 0.5mm (wherein
Represents the median particle size of the kth sample,
denotes the median particle diameter of the sample at the k +1 th run, k denotes the k-th run,
the difference value of the median particle diameters of particle samples obtained from the k-th screening test and the k + 1-th screening test is calculated, namely when the calculated mass of the next weighed particle sample is smaller than the mass of the particle sample of the test or the mass of the next weighed particle sample is converged to the mass of the particle sample of the test, the particle grading characteristics of the sample obtained from the screening test can represent the overall particle grading characteristics, and the error meets the requirement, and the test is ended.
In the present invention, the actual screening can be specifically defined according to the particle characteristics, wherein, for example, the particle size is from-0.5 mm to 0.5mm, and generally, the smaller the defined value is, the more accurate the test result is, the more the number of cycles of the test is likely to be.
The screening instrument for detecting the grading characteristic reliability of the granular material has the following logic analysis steps and design ideas:
determination of the number of samples
From the perspective of probability, if a certain amount of particle materials in the particle population are selected as samples to perform the screening test, the probability of each particle in the particle population being selected is equal, which is actually a simple random sampling process. Assuming that the number of particle populations is N (tending to infinity), in order to obtain the grading distribution characteristic of the particle populations, the tested particles in the population can be divided into two classes according to whether they are within a specified particle group interval, and each particle under investigation is defined as follows:
in the formula, YiThe value of the ith particle in the population is 1 if the particle size of the ith particle belongs to the set of particles, and 0 if not.
Based on the above definitions of the assignment of the particles, in the population of particles, there is N if the particle size of the particulate material belongs to the jth group (j ═ 1,2,3, …, w; w is the total group number)jThe number percentage of the particles belonging to the jth particle group is:
in the formula, PjIs the percentage of the granules belonging to the jth granule group in the granule population,
is the average of the cumulative number of particles belonging to the jth particle group in the particle population.
Thus, in a sieve test of particulate material, the number n for the particles to be measuredallIf the number of particles belonging to the jth particle group (j ═ 1,2,3, …, w; w is the total number of particle groups) is njAnd the number percentage of the particles belonging to the specified jth particle group in the particle sample is as follows:
in the formula, pjIs the percentage of particles in the particle sample belonging to the jth particle group,
is the average of the cumulative number of particles belonging to the jth particle group in the material sample.
For screening tests performed by randomly taking a certain number of samples from the material population, it is mathematically simple to followMachine sampling method. Thus, the percentage p of particles belonging to the jth group obtained from the samplejIs the percentage P of particles belonging to the jth group of particles in the populationjThrough mathematical calculation, the variance of the unbiased estimate of (a) can be obtained as:
in the formula, V (p)j)、
Are all statistical variances, S, of the particle samples belonging to the jth particle group2The variance of the overall particle size distribution of the particles is calculated as follows:
combining mathematical knowledge of probability statistics, it can be known that in simple random sampling, the error between the parameter estimation value P obtained from the sample and the actual value P of the population can be controlled within a specified limit, and quantitative determination is performed through two indexes of confidence 1-alpha and absolute error limit d, that is:
further, according to the bilateral quantile u in probability statisticsα/The definition of 2 can be seen:
in the formula (I), the compound is shown in the specification,
are all statistical variances in the particle samples belonging to the jth particle group.
Further, combining formula (4), formula (6), and formula (7), we can obtain:
as can be seen from equation (8), the number of particles in the jth particle group in the sample depends on 3 criteria: total number of particulate materials N, accuracy control index uα/2D and variance S of particle population size distribution2. That is, when the number N of the material population is larger, the required accuracy of the screening result is higher, and the particle size distribution of the particle population is wider, the required number of samples participating in the screening test is larger. Whereas in engineering practice activities the number N of particle populations tends to go to infinity, therefore, in combination with equation (5), equation (8) can be further simplified as:
thus, the number of samples that should be needed to determine the jth bin is obtained. Further, to determine the particle distribution range of all w particle groups in the sieving test, the total number of particle samples n requiredallThe calculation formula is as follows:
because P is more than or equal to 0j1 or less, as can be seen from the basic inequality:
at this time, an extreme value of the total number of particle samples for the sieving test in formula (10) is obtained as follows:
as can be seen from experience, under certain conditions, it participates in the screeningThe larger the number of samples tested, the closer the test results are to the true particle grading characteristics of the population of particles. Thus, conserved nallThe maximum determined in equation (12) can be taken, i.e.:
therefore, as can be seen from formula (13), the total number of particle samples selected in a screening test can be determined jointly by the accuracy control indexes (confidence 1- α, absolute error limit d) of the screening test. For example, in a screening test, if the confidence level 1- α of the initial design test results is 95%, the absolute error limit d is 7.07% (or d)20.005), the minimum number of particle samples required for calculation is 768, that is, when one sieving test only needs to take 768 particles from the total as sieving samples at random, the particle size obtained after the sieving test and the error between the particle grading characteristic and the particle grading characteristic of the particle material can be guaranteed to be controlled within +/-7.07%.
Second, determining the sample quality
Further, in the screening test process, the particle number is not used as a control index, but the quality of the particle sample is used as a control standard. Thus, before the particle sieving test is performed, the average density ρ of the particulate material is obtained by a density test, and the required sample mass calculation is as follows:
wherein m is the mass of the sample,
for the median particle size of the particulate material, w particle groups and the number of particles n within each particle group interval are designed according to a sieve testjThe median particle diameter is defined as the mass equivalent particle diameter of the entire particle sample, and is calculated as follows:
in the formula, DjThe median size of the jth particle group is the average value of the upper and lower limit particle sizes of the jth particle group; ρ is the average density of the particulate material.
In engineering practice, the median particle size of the particle grading characteristic curve of the particle size of the particulate material and its distribution is evaluated
With the maximum particle diameter D of the particlesmaxMinimum particle diameter DminHalf of and
there are only 3 relationships between them and the 3 relationships are discussed below to determine the sample mass required to participate in the screening test.
When in use
Then, in combination with equation (14) for calculating the sample mass, the sample mass required for analyzing the grain composition characteristics can be obtained as:
at the same time, if for some particulate materials, their maximum particle size DmaxFar greater than the minimum particle diameter DminThen, the minimum particle diameter D in the formula (16)minThe influence of (a) is substantially negligible, and equation (16) for calculating the sample mass can be further simplified as:
when in use
It is shown that the particulate material is predominantly fine, relatively poor in coarse and overall smaller in median particle size. In the same case, however, it can be seen from equation (14) that the larger the median size of the particle population, the more the required sample mass, and the closer the screening result of the particle sample to the grading characteristic of the particle population, which indicates that in this case, the sample mass calculated according to equation (14) is conservative, and the screened sample grading characteristic can ensure that the error between the sample mass and the grading characteristic of the particle population is controlled within the accuracy range.
When in use
When the content of fine particles in the particulate material is relatively low and the content of coarse particles is mostly high, the median particle size of the total particles is large, and if the formula (14) is continuously and directly adopted to determine the sample mass required by the test, a large test error may be generated. Therefore, for this case, the required sample quality can be determined by adopting a loop iteration method to ensure the reliability of the sample test result. The method comprises measuring a sample with a certain mass, and obtaining the particle size distribution PSD of the sample by a first screening test1Assuming that the particle grading PSD is now1Does not meet the reliability requirement, and the combination formula (15) can be formed by grading PSD with particles1Calculating the median particle diameter of the sample
Then will be
Substituting into formula (14) to obtain the sample mass to be weighed for the second screening test, and further obtaining the PSD for the second screening test2And
the iteration is circulated until
In the range of-0.5 mm to 0.5mm (wherein
Represents the median particle size of the kth sample,
denotes the median particle diameter of the sample at the k +1 th run, k denotes the k-th run,
the difference between the median particle diameters of particle samples obtained from the k-th and k + 1-th screening tests can be specifically defined according to particle characteristics in actual screening, wherein, for example, -0.5mm to 0.5mm, generally speaking, the smaller the defined value, the more accurate the test result is, the more the number of cycles of the test is possible), that is, the calculated mass of the next-weighed particle sample starts to be smaller than the mass of the particle sample of the test, or the mass of the next-weighed particle sample starts to converge on the mass of the particle sample of the test, the cycle is ended, which indicates that the particle grading characteristics of the sample obtained from the current screening test can represent the particle grading characteristics of the particle population, and the precision meets the requirement.
Compared with the prior art, the beneficial results of the invention are as follows:
1. the device can be used for carrying out screening tests on various granular materials to obtain the granularity and the grain grading characteristics of the granular materials, and lays a foundation for further classifying the granular materials and researching the relevant physical mechanics and chemical characteristics of the granular materials. The vibrating screening system disclosed by the invention adopts the inclined rectangular screen box, and the screen box on the higher side of the topmost layer is filled with particles to be tested, so that the particles can be screened in a free jumping manner along the longest path of the screen box, and the screening efficiency is improved. Meanwhile, the rectangular sieve box is provided with an observation window, which is beneficial to directly observing the sieving condition of particles in each layer of sieve box.
2. The vibration energy of the vibratory screening system of the present invention is continuously controllable. According to the flowing and jumping conditions of particles in each layer of sieve box, the excitation force intensity, the frequency and the amplitude of the vibration motor are flexibly adjusted through the frequency converter, the sieving test is accurately, quickly and efficiently completed, and the optimal sieving efficiency is achieved.
3. The vibration screening system is efficiently combined with the full-automatic collecting system, so that the granular materials in each screening box can be quickly recovered, and the measurement of the granular mass in each grain group interval is completed through the weighing sensor at the lower part of the storage box.
4. Based on the random sampling reliability theory in probability statistics, the invention generally realizes the design requirement of intelligently tracking and analyzing the grading characteristic reliability of the particle sample. The method comprises the steps of storing a mathematical model which is established based on a reliability theory and used for determining the quantity and the quality of samples and judging the error magnitude between the particle composition characteristics of the samples and the overall particle composition characteristics in a programmable logic controller through a programming method, further enabling hardware facilities such as a sensor, an acquisition instrument, a computer and the programmable logic controller to jointly form a neural center of the intelligent screening instrument, achieving quantitative tracking analysis on screening results of particle samples, and finally obtaining the optimal sampling quality and the material particle composition characteristics meeting the control precision requirements.
Based on the sampling analysis reliability theory, the invention researches and discovers that the total content of the particle materials, the size of the particle size distribution range and the precision control index are 3 important influence factors for determining the quantity of the selected samples in the screening test, and further designs a screening instrument capable of intelligently tracking and analyzing the particle sizes and the distribution characteristics of the particle samples based on the reliability theory, and obtains the optimal sample quantity required by meeting the control precision requirements of the total particle sizes and the distribution characteristics of the particle samples by inputting the specified precision index in a computer control interface before the test. Therefore, the intelligent screening instrument not only realizes accurate, fast and efficient acquisition of the overall particle grading distribution characteristics of the particle materials, reveals the design concept of green, energy conservation and environmental protection, but also has important methodology significance for guiding the development of related scientific research and engineering practice.
In addition, the intelligent screening instrument disclosed by the invention is simple in structure, convenient to install and flexible in test operation, accords with the design concept of green, energy-saving and environment-friendly, and meets the requirements of carrying out screening tests on various different granular materials.
Drawings
FIG. 1 is a schematic diagram of the configuration of an intelligent sizer of one embodiment of the present invention;
FIG. 2 is a flowchart of the process for analyzing the results of a sample test using the sizer of the present invention;
fig. 3 is a typical 3-particle grading profile.
In the figure
1-base plate, 2-frame beam, 3-vibration table, 4-pier, 5-compression spring, 6-centrifugal vibration motor, 7-frequency converter, 8-acceleration sensor, 9-telescopic column, 10-feeding box, 11-steel hoop, 12-horizontal barrier baffle, 13-dust cover, 14-rectangular sieve box, 15-fixed lock, 16-sieve plate, 17-discharging vertical baffle, 18-discharging pipe and its tip, 19-storage box, 20-storage box outlet, 21-weighing sensor, 22-bearing platform, 23-data collector, 24-programmable logic controller, 25-operation controller, 26-computer, 27-fastening fixture, 28-observation window, 29-rubber cushion.
Detailed Description
The present invention will be described in detail below with reference to the embodiments with reference to the attached drawings. It should be noted that the embodiments and features of the embodiments may be combined with each other without conflict. For convenience of description, the words "upper", "lower", "left" and "right" in the following description are used only to indicate the correspondence between the upper, lower, left and right directions of the drawings themselves, and do not limit the structure.
A screening instrument for intelligently detecting the grading characteristic reliability of a particle material is shown in figure 1 and comprises a vibration screening system, a full-automatic collecting system, a data acquisition module, a programmable logic controller, a computer 26 and other hardware facilities.
In this embodiment, the vibrating screen system includes a supporting frame structure, an elastic vibrating module, a rectangular screen box 14, and a feeding and discharging device. The supporting frame structure comprises a base plate 1, a telescopic frame beam 2, a horsewheel and the like. The base plate 1 can be made of steel materials, the machining thickness of the base plate is strictly controlled, and the base plate 1 has enough requirements on rigidity, strength, stability and durability due to the fact that equipment needs to experience long-term dynamic load in the using process. The four corners of the bottom surface of the base plate 1 are provided with the Fuma wheels, so that the vibration screening system can be flexibly moved. The elastic vibration module is arranged on the upper part of the base plate 1.
In this embodiment, the elastic vibration module mainly includes a tilting vibration table 3, a compression spring 5, a vibration motor 6, and the like. The inclined vibration table 3 is designed to be of a single-side inclined type, the inclination angle is generally controlled to be about 0-5 degrees, the main function of the inclined vibration table is to realize that the granular materials can be screened and jumped along the long edge direction in the rectangular screen box 14 in the screening test process, the maximum screening path of the granules is guaranteed, the automatic collection of the granular materials in each layer of screen box 14 is facilitated, and the granule loss in the screening process is reduced. Meanwhile, the upper part of the inclined vibration table 3 is provided with a fastening clamp 27 for fixing the lowermost rectangular screen box 14, which has the function of preventing the screen box 14 from generating structural self-vibration in the vibration screening process and maximally realizing the upward transmission of vibration energy into each layer of rectangular screen box 14.
In this embodiment, the loading source of the elastic vibration module is a centrifugal vibration motor 6. The vibration motor is fixed at the central position of the bottom surface of the inclined vibration table 3 by bolts, the vibration motor has the function of weakening the horizontal vibration force component generated in the loading process of the vibration motor 6 to the maximum extent by utilizing the structural dead weight of the elastic vibration module, and a counterweight can be fixed at the bottom surface of the inclined vibration table 3 if necessary. Further, a frequency converter 7 is installed between the centrifugal vibration motor 6 and the input power source, and functions to change the vibration intensity thereof by adjusting the input frequency of the vibration motor 6. Meanwhile, an acceleration sensor 8 is installed at a proper position, close to the vibrating motor 6, on the bottom surface of the inclined vibrating table 3, an output port of the acceleration sensor 8 is connected with hardware facilities such as a data acquisition instrument 23 and a computer 26, and therefore the output vibration strength of the vibrating motor 6 in the screening test process is monitored in real time.
Further, the inclined vibration table 3 is fixed on the top of 4 groups of compression springs 5, and the total number of the compression springs 5 is 8. In the invention, 8 compression springs 5 are fixed at the tops of 4 rigid piers 4, and rubber cushions with the thickness of about 10-20mm are arranged among the compression springs 5, the inclined vibration table 3 and the rigid piers 4, and the function of the rubber cushions is to reduce noise. Furthermore, 8 compression springs 5 of the same factory batch and the same specification are selected, so that the consistency of basic indexes such as the size, the rigidity coefficient and the like of the compression springs is guaranteed to the maximum extent, and the stability and the harmony of the upper vibrating body system in the whole test process are favorably maintained.
In this embodiment, the telescopic frame beam 2 is fixed to the base plate 1 side and is spaced from the vibration module by a suitable distance. The feeding box 10 is fixed on the upper portion of the frame beam 2 through the steel hoop, the frame beam 2 is flexibly adjusted to a proper height according to the number of the screening boxes 14 required by the particle material test, and a particle material sample to be screened is conveniently loaded from the feeding hole. In the lower part of the funnel-shaped structure of the feeding box 10, a horizontal blocking partition is installed, which has the function of flexibly adjusting the amount of particles entering the screen boxes 14, preventing excessive particle samples from flowing into the topmost screen box 14 at one time and causing excessive particle amount in each layer of screen boxes 14 to reduce the precision and quality of the screening test.
In the embodiment, the full-automatic collection system is innovatively adopted to realize timely tracking and collecting of the particle mass in each particle group range. The full-automatic collecting system comprises a storage box, a weighing sensor 8, a telescopic upright post 9 and the like together. According to the 14 numbers of the rectangular sieve boxes selected for use, the discharge pipe tip of each sieve box 14 is aligned to the feed inlet of the material storage box, and the vertical discharge partition plate is opened to automatically collect granular material samples in each layer of sieve box 14. The weighing sensor 8 is horizontally arranged at the lower part of each storage box, the weighing sensor 8 is further fixed on a bearing platform, and each bearing platform is fixed on the telescopic upright post 9 through the steel hoop level, so that the relative positions of a discharge pipe tip of the sieve box 14 and a feed inlet of the storage box can be flexibly adjusted, and the complete collection of residual granular materials in each layer of sieve box 14 can be realized to the maximum extent. The weighing sensor 8 realizes automatic collection of the particle mass in different particle groups, and the particle mass is input into the programmable logic controller through the data acquisition instrument 23, so that the reliability between the particle size of the particle sample, the distribution condition of the particle sample and the particle grading characteristics of the material overall is further judged through intelligent tracking analysis.
The content is the theoretical basis for developing the reliability screening instrument for the grading characteristic of the intelligent analysis material particles, the screening instrument has the advantages of high automation degree, wide application range and the like, and for example, the screening instrument can be used for developing intelligent screening tests on the sand, soil, grains, sugar, salt, medicines, various ore, coal, lime, fly ash and other particle materials with various grading characteristics.
In the following, the method for intelligently tracking and analyzing the reliability of gradation characteristics of a particle sample will be described by further combining the device characteristics and the using method of the apparatus, when facing an unknown particle material, as shown in fig. 2, the specific steps are as follows:
1) the average density of the population of particulate material to be measured should first be determined. The density of the material is obtained through a density test and is input and determined in a control interface of the computer 26, and meanwhile, a control precision index value of a screening test is input in the control interface of the computer 26, namely, the values of confidence 1-alpha and absolute error limit d in the intelligent analysis sample quality theory are determined and calculated.
2) According to the requirements of screening test several rectangular screen boxes 14 with proper pore size can be selected, and the pore size value can be inputted into the analysis interface of computer 26 and defined. Meanwhile, the sieve boxes 14 are placed on the vibration screening system from bottom to top in order according to the hole diameters from small to large, wherein the side wall of the sieve box 14 at the lowest layer is locked by a fastening clamp 27 on the surface of the inclined vibration table 3, the sieve boxes 14 at all layers are fixed pairwise by fixing locks 15 on the side wall in sequence, finally the rectangular sieve box 14 at the top layer is sealed by a dustproof cover, and meanwhile, the relative positions of a feed inlet of each storage box and a tip nozzle of a discharge pipe of the sieve box 14 are respectively adjusted, so that the screened particles can smoothly enter the storage boxes through the discharge pipes.
3) The particle size of the larger particles is measured from the material population by simple methods such as visual inspection, graduated scale measurements, and the like. Half of this larger particle size value is then entered in the computer 26 control interface as the initial average particle size for the first sampling reference
The mass of the particle sample to be weighed for carrying out the first screening test is obtained by programmed calculation based on the formula (14), and in addition, the particle sample is weighed so as to ensure that the particle sample approximately matches the particle size distribution range of the whole material in terms of size as much as possible. The weighed sample material is then placed in the feed box 10, and after checking it is correct, the vibrating motor 6 is started, and the feed screen is opened to allow the material to flow under its own weight into the topmost screen box 14.
4) In the screening process, the flowing form of particles in each layer of screen box 14 is observed through the observation window 28 on the side wall of the rectangular screen box 14, in order to achieve the optimal screening effect, the vibration intensity, the frequency and the amplitude of the vibration screening system can be changed by adjusting the frequency converter 7 of the vibration motor 6, so that the particles can stably and slowly flow to one side of the discharge pipe in each layer of screen box 14, the vertical partition plate of the discharge port is opened, and the particles pass through the outlet pipe to be automatically collected by the storage box.
5) After all the particles in the screen boxes 14 of each layer flow into the storage boxes of each layer, the vibration motor 6 is turned off. At the moment, the weight sensor 8 is used for collecting the mass of the particles in each storage box, and signals of the density, the mass of each layer of particles and the aperture size are further programmedThe input of the input port of the logic controller is calculated by the intelligent screening program to obtain the number n of the particles in each particle group intervaljMedian particle diameter of sample
And particle size distribution characteristic PSD1And displayed on the computer 26 control interface.
6) Based on the intelligent screening test analysis method for judging the sample quality, the median particle size obtained in the screening test is calculated by an algorithm designed by a programmable logic controller
And
for comparison, the particle size of the particle diameter D is determined based on the maximum particle diametermaxIn other words, the minimum particle diameter DminThe influence of (A) can be ignored, and the median particle size can also be used in the algorithm writing process
And
a comparison is made. If calculated, the median particle size of the test sample
The quality of the sample weighed in the screening test meets the precision requirement, namely the particle grading characteristic obtained by the test can represent the particle distribution condition of the particle total; when in
And the quality of the sample weighed in the screening test is insufficient, and the particle grading characteristics obtained in the screening test cannot represent the particle distribution condition of the particle population and exceed the set precision range. Next, the computer 26 program will run this test to obtain the median particle size
Substituting the language compiled based on the formula (14) and then calculating the sample mass to be weighed in the next test, simultaneously recovering the materials in the storage box, cleaning up each layer of rectangular sieve box 14, and waiting for the next set of test.
7) Repeating the steps 2) -6) according to the mass of the sample to be weighed determined in the last screening test until the median particle size of the particle sample in the (k + 1) th screening test after program operation of the programmable logic controller meets the requirement
Namely, it is
In the range of-0.5 mm to 0.5mm (wherein
Represents the median particle size of the kth sample,
denotes the median particle diameter of the sample at the k +1 th run, k denotes the k-th run,
the difference between the median particle diameters of particle samples obtained from the k-th and k + 1-th screening tests can be specifically defined according to particle characteristics in actual screening, wherein, for example, -0.5mm to 0.5mm, generally speaking, the smaller the defined value, the more accurate the test result is, the more the cycle number of the test is possible), that is, the calculated mass of the next-weighed particle sample is less than the mass of the particle sample obtained from the test, or the mass of the next-weighed particle sample is converged to the mass of the particle sample obtained from the test, which indicates that the particle grading characteristics of the sample obtained from the current screening test can already represent the overall particle grading characteristics, and the error meets the requirement, and the test is ended.
The foregoing examples are set forth to illustrate the present invention more clearly and are not to be construed as limiting the scope of the invention, which is defined in the appended claims to which the invention pertains, as modified in all equivalent forms, by those skilled in the art after reading the present invention.
Claims (11)
1. A method for screening particulate materials using a screening apparatus for detecting the reliability of the grading characteristics of the particulate materials, wherein the screening apparatus for detecting the reliability of the grading characteristics of the particulate materials comprises a base plate (1), an elastic vibration module, a column (9) and a frame beam (2) mounted on the base plate (1), a vibration table (3) mounted on the elastic vibration module, and a screen box (14) disposed on the vibration table (3); a feeding box (10) is fixedly arranged at the upper part of the frame beam (2), and an outlet of the feeding box (10) extends into the sieve box (14); a bearing platform (22) is arranged on the upright post (9), a plurality of storage boxes (19) are arranged on the bearing platform (22), and the discharge hole of the screen box (14) is aligned with the feed hole of the storage boxes (19);
the sieve box (14) is divided into a plurality of grids by a plurality of sieve plates (16) which are horizontally arranged from bottom to top, wherein the sieve pore diameter of the sieve plate of the upper layer is larger than that of the sieve plate of the lower layer, and a storage box (19) is correspondingly arranged at the discharge port of each grid;
the single side of the vibrating table (3) is obliquely arranged, wherein the feeding box (10) is positioned on the higher side of the vibrating table (3), and the storage box (19) is positioned on the lower side of the vibrating table (3);
the method of screening particulate material comprises the steps of:
s1, determining the average density of the whole particle material to be measured, and fixing the sieve box (14) on the vibration table (3);
s2, weighing sample materials, placing the sample materials in a feeding box (10), starting an elastic vibration module, and enabling the sample materials to flow into a sieve box (14) under the action of self weight and move towards a discharge port until the sample materials flow into a storage box (19);
s3, stopping the elastic vibration module after all sample materials flow into the corresponding storage box (19), and weighing the weight of the particles collected in the storage box (19);
s4: the density and each of the particles collected in step S3The layer particle quality and aperture size signals are input from an input port of the programmable logic controller, and the number n of particles in each particle group interval is obtained through calculationjMedian particle diameter of sample
And particle size distribution characteristic PSD1(ii) a Calculating the median particle diameter obtained in the screening test by a programmable logic controller
And
make a comparison if
It indicates that the weighed sample mass meets the precision requirement, that is, the particle grading characteristic obtained by the test at this time can represent the particle distribution of the particle population, if
The quality of the weighed sample is insufficient, and the particle grading characteristics obtained by the screening test cannot represent the particle distribution condition of the particle population and exceed the set precision range;
repeating the steps S1-S4 according to the sample mass to be weighed determined by the last screening test until the median particle diameter of the particle sample of the (k + 1) th screening test after the operation of the programmable logic controller meets the requirement
In the range of-0.5 mm to 0.5mm (wherein
Represents the median particle size of the kth sample,
denotes the median particle diameter of the sample at the k +1 th run, k denotes the k-th run,
the difference value of the median particle diameters of particle samples obtained from the k-th screening test and the k + 1-th screening test is calculated, namely when the calculated mass of the next weighed particle sample is smaller than the mass of the particle sample of the test or the mass of the next weighed particle sample is converged to the mass of the particle sample of the test, the particle grading characteristics of the sample obtained from the screening test can represent the overall particle grading characteristics, and the error meets the requirement, and the test is ended.
2. A method for screening particulate material according to claim 1, wherein the resilient vibration module comprises a plurality of abutments (4) provided on the base plate (1), compression springs (5) mounted between the tops of the abutments (4) and the vibration table (3), and a vibration motor (6) mounted on the vibration table (3).
3. A method of screening particulate material as claimed in claim 2 wherein the vibration motor (6) is electrically connected to a frequency converter (7).
4. A method of screening particulate material as claimed in claim 1 wherein adjacent compartments of the screen box (14) are locked together by a fixing lock (15) and the lowermost compartment is fixed to the vibratory table (3) by a securing clamp (27).
5. A method of sizing particulate material according to claim 1, wherein the angle of inclination of the vibratory table (3) is between 0 ° and 5 ° to the horizontal.
6. A method of screening particulate material as claimed in any one of claims 1 to 5 further comprising a computer (26), a programmable logic controller (24), an operational controller (25) and a data acquisition instrument (23); a bearing sensor (21) is arranged between the bearing platform (22) and the material storage box (19); the computer (26) is communicated with an operation controller (25), the operation controller (25) is communicated with a programmable logic controller (24), the programmable logic controller (24) is communicated with a data acquisition instrument (23), and the data acquisition instrument (23) is electrically connected with the load-bearing sensor (21).
7. A method of screening particulate material according to any one of claims 1-5, characterized in that the frame beams (2) are height-adjustable telescopic beams and/or the uprights (9) are height-adjustable telescopic columns.
8. A method of screening particulate material as claimed in claim 2, wherein the vibration motor (6) is a centrifugal vibration motor.
9. A method of screening particulate material as claimed in claim 2 wherein rubber cushions (29) are provided between the compression spring (5) and the vibratory table (3) and between the compression spring (5) and the abutment (4).
10. A method of screening particulate material as claimed in claim 4, wherein the screening box (14) is fitted with a dust cap (13) at the top.
11. A method of sizing particulate material according to claim 4, wherein each compartment has a viewing window (28) formed in a side wall thereof.
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| CN201910097937.8A CN109759316B (en) | 2019-01-31 | 2019-01-31 | Screening instrument and screening method for detecting grading characteristic reliability of granular material |
| AU2019204680A AU2019204680B1 (en) | 2019-01-31 | 2019-07-01 | Sieving instrument and sieving method for detecting reliability of particle size distribution characteristics of granular material |
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| CN110538789B (en) * | 2019-09-02 | 2021-08-24 | 马鞍山市新桥工业设计有限公司 | Ore screening device and using method thereof |
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| CN112934670B (en) * | 2021-01-27 | 2022-07-15 | 中国石油大学(华东) | Automatic rock debris cleaning device provided with multi-aperture scroll type screen |
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| CN113058847B (en) * | 2021-04-23 | 2022-02-22 | 哈尔滨工业大学 | Automatic screening and mixing system and method for anti-frost heaving filler of high-speed railway foundation |
| CN114324078B (en) * | 2021-12-24 | 2024-07-26 | 中煤科工清洁能源股份有限公司 | Particle size identification method, device, equipment and medium |
| CN114563300B (en) * | 2022-02-28 | 2023-09-29 | 中冶华天工程技术有限公司 | Online detection method for granulating effect of cylinder mixer |
| CN114577683B (en) * | 2022-02-28 | 2023-11-28 | 唐山市市场监管综合执法局 | Detection device for detecting granularity of fertilizer and application method thereof |
| CN115415170B (en) * | 2022-09-01 | 2023-09-29 | 苏州胤煌精密仪器科技有限公司 | Intelligent particle classification particle analyzer |
| CN118321140B (en) * | 2024-06-12 | 2024-09-17 | 江苏开启牧业有限公司 | Intelligent control system for feed production |
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