GB/T 15591-1995 Method for determining the reflectivity distribution diagram of commercial coal
Some standard content:
National Standard of the People's Republic of China
Judging method for reflectogram of commercial coal Subject content and scope of application
GB/T15591.1995
This standard specifies the determination of random reflectivity of vitrinite of commercial coal, calculation of results, drawing of reflectivity distribution diagram and determination method. This standard is applicable to bituminous coal and low-grade anthracite. Lignite should also be used as a reference. 2 Reference standards
GB6948 Determination method of vitrinite reflectivity of coal 3 Determination of random reflectivity of vitrinite
3.1 Instrument
3.1.1 Microscope photometer equipped with microcomputer and control system, or general microscope photometer. The total magnification is not less than 500 times. 3.2 The adjustment, inspection, calibration of standard film and oil, optical film requirements, measurement conditions and objects of the microphotometer shall be carried out in accordance with the provisions of GI36948. 3.3 Determination of point line distance and number of measuring points
3.3.1 Point line distance
Use 0.4mm×0.4mm or 0.5mm×0.5mm3.3.2 Number of measuring points
Use a coal brick optical film with a diameter of 25mm or a side length of 25mm, and measure more than 250 points. If the variation range of 98% of the measured values is greater than 0.4%, the second coal brick optical film should be measured.
Note: If 250 points can meet the requirements, the first piece is not measured. After measuring the entire piece according to the specified point line distance, if the number of measuring points is less than the specified number, it should be explained in the report. 4 Calculation of measurement results
The average value and standard deviation of random reflectivity are calculated according to formula (1) and formula (2): R
Where: Ra average random reflectivity;
R, the reflectivity measurement of the,th measuring point, 2.3S-·standard deviation;
Approved by the State Administration of Technical Supervision on June 12, 1995·(1)
Implementation of 1996-0201
Number of measuring points.
5 Drawing of reflectivity distribution diagram
GB/T 15591—1995
Take the reflectivity interval of 0.05% as half-step, count the number of measuring points in each interval and calculate the frequency (f). Draw the reflectivity distribution diagram with frequency as the ordinate and random reflectivity (Rran) as the abscissa. 6 Determination of reflectivity distribution diagram
6.1 Determination shall be made according to the provisions of Table 1.
Table 1 Coding system for the reflectivity distribution diagram of commercial coal Code
Standard deviation
Division index
Number of notches
No notch
>0. 1~0. 2
No notch
1 notch
2 notches
2 or more notches
Note: The reflectivity distribution diagram with the characteristics of code 1 can also be obtained from a single coal seam of lean coal and anthracite. The typical distribution diagram corresponding to the coding system is shown in Appendix A. 6.2 The report content and format of the discrimination results are shown in Appendix B. 7 Precision
The repeatability of the measurement shall comply with the provisions of Table 2. Table 2
Single coal
Simple mixed coal
Complex mixed coal
Mixed coal with 1 notch
Mixed coal with 2 notches
Mixed coal with more than 2 notches
Repeatability, %
Code (
Code 2
Code 1
GB/T 15591---1995
Appendix A
Coding of reflectivity distribution map of commercial coal and its typical example (reference)
Rran1.11%
Rran1.27%
40%Factory
Code 1
Code 3
Rran0. 90%
Rranl.21%
Code 5
Rran1.31%
GB/T15591—1995
This standard adopts the International Coding System for Medium-Rank Coal and High-Rank Coal (1988 edition) of the United Nations Economic Commission for Europe. Appendix B
Commercial Coal Reflectivity Distribution Diagram Identification Report
(Reference)
Sample Submission Unit:
Calculation Data:
Reflectivity Distribution Diagram:
Judgment Result:
Attachment Add explanation:
Reporter:
Additional explanation:
Minimum value-
Maximum value-
Sample number:
Average value-
Standard deviation-
Number of measuring points-
Code:
Type:
Audit:
This standard is proposed by the Ministry of Coal Industry of the People's Republic of China. This standard is under the jurisdiction of the National Coal Standardization Technical Committee. 1.0
Year-Month-Day
Date:
This standard is proposed by the Ministry of Coal Industry of the People's Republic of China. Xi'an Branch of China Coal Research Institute and Beijing Graduate School of China University of Mining and Technology are responsible for drafting. The main drafters of this standard are Li Xiaoyan, Chen Muqiu, Jin Kuili and Mao Heling. This standard is interpreted by Xi'an Branch of China Coal Research Institute. 482
Sample source:
Discrimination method of commercial coal reflectivity distribution map (GB/T15591-1995) Preparation instructions
(Li Xiaoyan, Xi'an Branch of China Coal Research Institute) The vitrinite reflectivity distribution map is a new coal petrology index. It can accurately judge the nature of commercial coal according to the distribution characteristics of reflectivity measurement in coal. It is an indispensable indicator in coal trade. The technical indicators of the few are accepted as one of the indicators of the coding system by the international coal classification, which is particularly effective in judging mixed coal.
my country is a large coal-producing country with a wide range of coal for export and industry. The current commercial coal is based on chemical indicators, which does not fully reflect the properties of mixed coal and is inconsistent with the international commercial coal standards, causing many inconveniences to coal trade. For this reason, the Ministry of Coal Industry applied to formulate the national standard "Method for Discrimination of Commercial Coal Reflectivity Distribution Map". The principle followed in formulating this standard is: based on international standards, analyze and verify the reflectivity distribution characteristics of my country's commercial coal, and propose a scientific discrimination method. Internationally, the classification schemes of Italy and Germany are now recognized (Report of the Fifth International Coal Classification Conference of the United Nations Economic Commission for Europe, Zhong Ming, 1985). The Italian scheme divides commercial coal into six types based on the two parameters of standard deviation and number of notches; the German scheme divides ten types based on the three parameters of standard deviation, number of peaks and number of notches. Compared with the two, the Italian scheme is concise and has reasonable divisions. The international coal classification refers to this scheme (Economic Commission for Europe, "International Coding System for Medium-Rank Coal and High-Rank Coal", United Nations New York, 1988). In order to get closer to the international standard, the Italian scheme is selected as the reference basis. This standard is for commercial coal. The purpose of establishing the standard is to determine whether the commercial coal is a single coal or a mixed coal, and the simplicity and complexity of the mixture.
The content of this standard research: Random reflectivity measurement of various industrial coals, understanding the characteristics of the reflectivity distribution map of different coals, and providing a theoretical basis for the formulation of discrimination methods; testing various samples in the same laboratory and between laboratories, verifying the influence of the number of measurement points on the test results, comparing and analyzing the errors between tests, and proposing test accuracy requirements; finally proposing a discrimination method suitable for my country's commercial coal. The main workload of formulating this standard:
a) Collect 24 samples of various types. Among them, there are 7 coal seam coal samples, 6 export coal samples, 5 washed coal samples, and 6 coking coal samples. b) 19 laboratory simulated mixed samples and 2 verification samples. c) 11 for industrial analysis and elemental analysis, and 120 for reflectivity measurement and distribution diagram drawing under microscope. This standard is led by Xi'an Branch and cooperated by Beijing Graduate School of China University of Mining and Technology. 1 Test Description
Basic requirements for testing, such as sample quality, instrument calibration, standard sample selection, test methods, etc., must be strictly implemented in accordance with relevant standards. 1.1 Test Instrument
The microphotometer imported from China recently, with an HP-85 microcomputer, is an ideal test equipment: considering the existing instrument conditions in China, it can also be measured on a general photometer. Use PC-1500 or other microcomputers for statistical analysis. The instrument needs to be stable for more than 3 to 5 hours. 1.2 Test Precautions
For random reflectivity test, remove the front polarization, do not rotate the stage, use the push ruler brake button to control the point line distance, and test directly when you see the test object. Select at least two standard samples before testing to determine the linear relationship of the instrument. During the test, check with the standard every 50 or 100 measuring points to observe whether the instrument is stable. When checking the standard sample, if the measured value and the theoretical value are within the allowable error range (≤0.02%), the previous measured value is valid and the test continues; if the standard sample inspection has exceeded the allowable error, it means that the instrument is unstable and the previous measured value is invalid. Stop the test, adjust the instrument to stabilize, and restart the test. In order to ensure the representativeness of the test and the accuracy of the measured value, the test is carried out according to the specified point-line distance until the entire piece is measured. If the number of measured points is insufficient or exceeds the specified number, the final number of points after the entire piece is measured is used for calculation. 544
1.3 Result expression
The results are expressed in two ways: statistical calculation and drawing. The parameters of statistical calculation include reflectivity distribution range (minimum to maximum), average value, standard deviation, and number of measurement points. The standard deviation reflects the dispersion of the measured value. The distribution range and continuity of the measured value have a great influence on it. It is an important parameter for judging the properties of commercial coal. The distribution diagram is the main expression of the test results. The measured value histogram is used. The vertical axis is the frequency, and the number of measured points in each interval is the percentage of the total number of measured points; the horizontal axis is the reflectivity value, and the appropriate interval is selected to divide it into several orders. From a statistical point of view, the size of the interval directly affects the characteristics of the distribution graph. If it is too small, there will be spaces, and if it is too large, the reflection of the characteristics of the distribution graph will be limited. There have been examples of 0.02%, 0.05%, and 0.1% in the world. For the convenience of comparison, 0.05% is used. Conclusion: It is the conclusion of the test results. It can be expressed by coding or type. 1.4 [The meaning of the mouth
There are peaks and valleys in the reflectivity distribution graph, which is the main feature of commercial coal. The valley between peaks is called a notch. In order to prevent errors in judgment, it is necessary to explain the meaning of the notch. The English word "gap" appears in the Italian scheme (the document of the Fourth Meeting of the International Coal Classification of the Economic Commission of the European Community in 1983), which is interpreted as disconnection, which is the discontinuity in the reflectivity distribution. The Chinese translation is discontinuity. Since the reflectivity distribution graph of a single coal is normally distributed, valleys and disconnections may appear between peaks only when different types of coal are mixed. The more types of coal are mixed, the more valleys or disconnections there are. Therefore, at the 8th International Coal Classification Conference in 1989, the original Italian meaning of "gap" was revised, and it was believed that in addition to discontinuous disconnections, it should also include unconnected valleys between peaks, so that "gap" was translated into "notch", and the revised meaning was adopted in this work. It is necessary to reiterate that although the meaning of notch has been determined, in fact, there are many varieties of commercial coal, and the distribution diagram of measured values is very complicated. Special attention should still be paid when distinguishing. Individual small disconnections, valleys and peaks cannot be rashly identified, and the condition of normal distribution should be considered. The so-called normal distribution is basically consistent with the distribution range of single coal of the same order. From this perspective, the judgment will not be wrong. 2 Characteristics of random reflectivity distribution diagram of commercial coal Commercial coal includes various industrial coals from bituminous coal to anthracite coal grades. The characteristics of reflectivity distribution diagrams are discussed in two categories below. 2.1 Single coal samples of different coal ranks
Seven coal samples were taken from underground coal seams, including Pingshuo long flame coal, Shizuishan gas coal, Puxian fat coal, Liulin coking coal, Zhangcun lean coal, Lingchuan lean coal, and Nayong anthracite. The test results are shown in Table 1:
Table 1 Reflectivity and coal index of coals of different ranks Samples
Pingshuo long flame coal
Shizuishan gas coal
Puxian fat coal
Liulin coking coal
Zhangcun lean coal
Lingchuan lean coal
Nayong anthracite
Reflectivity distribution
Range, %
0.46~0.77
0. 61~0. 88
0. 81~1. 04
1.21~~1.50bZxz.net
1.41~1.86
1.76~2.26
2.26~~3.09
Average value
Standard deviation
Distribution graph characteristics
Normal distribution
Normal distribution
Normal distribution
Normal distribution
Normal distribution||tt| |Normal distribution
Normal distribution
Table 1 shows that the reflectivity distribution range increases with the increase of coal rank. From long flame coal to fat coal, the difference in reflectivity distribution (maximum value-minimum value) shows a decreasing trend (0.31%-0.23%), and the standard deviation ranges from 0.06 to 0.04. From fat coal to anthracite, the difference in reflectivity distribution shows an increasing trend (0.23%-0.85%), and the standard deviation ranges from 0.04 to 0.19. Before lean coal, the difference in reflectivity distribution is less than 0.4%, and the standard deviation is less than 0.1. After lean coal, the difference in reflectivity distribution is greater than 0.5%, and the standard deviation is greater than 0.1. Among the 7 samples, the difference in reflectivity distribution and the standard deviation of anthracite are the largest, and the reflectivity distribution diagrams of the 7 samples are all normally distributed. The coal type determined by coal quality analysis is consistent with the coal rank determined by the reflectivity distribution diagram.
2.2.1 Industrial coal
A total of 17 samples were selected, including Beijing Coking Plant washed coal, Qinmu Island export coal base export coal and Shougang coking coal. It was found that except for a few samples whose reflectivity distribution diagram showed a normal distribution, the measured values of most samples were scattered, with a reflectivity distribution difference of 0.4%~～1.5%, a standard deviation of 0.1～0.28, and alternating peaks and valleys in the distribution diagram, showing the characteristics of coal combinations of different coal ranks. At this time, the average result given by the coal quality analysis (Table 2) cannot determine the mixing status of the coal.
Pingshuo (I)
Dashang (I)
Pingshuo ()
Datong (II)
Changjiatuo
Shougang-1
Shougang-2
Shougang-3
Shougang-4
Shougang-5
Shougang-6
2.3 Conclusion
Reflectivity distribution range
0.42~0.77
0.41～1.51
0. 49~1. 66
0.85～1. 59
0.41 ~~0. 84
0. 41~~0. 99
1. 02~1.81
0. 72~~1. 08
1. 04~1. 45
0.84~1.40
0. 80 ~1. 88
0.63~1.89
0.66~1.89
0.67~1.90
0.55~1.87
0.70~1. 86
Reflectivity and coal type indicators of industrial coal
Average value
From the analysis of the measured results of the above samples, it is believed that: standard deviation
Distribution diagram characteristics
Normal distribution
Normal distribution
Normal distribution
2 bee 1 notch
2 bee 1 notch
3 bee 2 notch
3 bee 2 notch
3 bee 2 notch
2 peak 1 notch
3 bee 2 four mouths
a) Any coal with normal distribution, random reflectivity distribution difference less than 0.4% and standard deviation less than 0.1 is single coal (the reflectivity distribution difference and standard deviation of single coal of high metamorphic bituminous coal and anthracite are larger). b) The distribution diagram is complex, the difference of random reflectivity distribution is greater than 0.4%, and the standard deviation is greater than 0.1. The coal is mixed coal. The more notches on the distribution diagram and the larger the standard deviation, the more complex the mixing degree is. c) As the coalification degree increases, the reflectivity distribution range of a single coal increases and the standard deviation increases. In short, the reflectivity distribution diagram can intuitively reflect the mixing status of coal. Stach et al. applied this method to guide coal blending and coking. The coal type or coal group was determined according to the reflectivity distribution on the horizontal axis, and the frequency of each segment on the vertical axis was counted to calculate the mixing ratio. Zhou Shuyi et al. used this method to guide coal blending and coking in China, and proposed the view that the higher the frequency at 1.1%, the better the coke quality. Therefore, the reflectivity distribution diagram is used to control the quality of commercial coal and is very effective in identifying mixed coal.
Laboratory simulation and classification scheme
Tests have shown that the reflectivity distribution diagrams of commercial coal vary greatly, and it is difficult to judge the degree of mixing directly from the diagram. The reflectivity distribution diagram of a single coal has strong regularity. Using six coal rank samples of bituminous coal as base samples, different methods of laboratory simulation mixing are carried out, and the recognition of its regularity is used as the basis for the method of judgment.
3.1 Simulated basic samples
According to previous research results, the reflectivity (maximum reflectivity, random reflectivity) boundaries of the six coal ranks of bituminous coal are shown in the figure below. The sample numbers and reflectivity values of the six base samples we selected are all within the boundaries of each coal rank. Long flame coal
Simulated base sample number
The random reflectivity distribution diagrams of the six samples are all normally distributed, and the coal rock and coal quality analysis results are shown in Tables 3 and 4. Table 3 Content of microscopic components of simulated base samples
Pingshuo long flame coal
Shizuishan gas coal
Puxian fat coal
Liulin coking coal
Zhangcun lean coal
Lingchuan lean coal
Pingshuo long flame coal
Shizuishan gas coal
Puxian fat coal
Liulin coking coal
Zhangcun lean coal
Lingchuan lean coal
3.1 Simulation method and results||tt ||Simulated base sample coal quality analysis results
A total of 19 samples were obtained by mixing adjacent, alternating, and different coal types in equal proportions (weight ratio) for six base samples. The test results of each group are described as follows:
a) Mixing of two adjacent coal types
The difference in random reflectivity distribution of the five samples is 0.4%~0.9%, the standard deviation is 0.07~0.24, there is no notch or one notch, and the possible codes according to the Italian scheme are 0, 1, and 3. The standard deviation of samples 1 to 2 with low coalification is less than 0.1, which is a single coal feature. This is because the reflectivity of the two coal samples is close. Samples 4 to 5 have notches, with a standard deviation of 0.14, which is not included in the six codes. The difference in random reflectivity distribution of four samples of two-phase coal mixture
is 0.5%~1.1%, the standard deviation is 0.13~0.35, there is one notch in each sample, and the possible code is 3. The results of samples 1~3 are the same as samples 4~5. c) The difference in random reflectivity distribution of four samples of three adjacent coal mixture
is 0.5%~1.1%, the standard deviation is 0.12~0.29, there are one or two notches, and the possible code is 4. The results of samples 1~~2~~3 are the same as samples 4~5. d) The difference in random reflectivity distribution of two samples of three-phase coal mixture
is 1.3%~~1.7%, the standard deviation is greater than 0.2, there are two notches, and the possible code is 4.
e): The difference in random reflectivity distribution of four samples of more than one type of coal is 1.3% to 1.8%, the standard deviation is greater than 0.2, there is no notch or there are three notches, and the possible code is 2.5.
3.3 Division indicators and schemes
The above tests show that the difference in reflectivity distribution, standard deviation, and notch are effective indicators for distinguishing the properties of commercial coal. The difference in reflectivity distribution is reflected in the standard deviation. The larger the difference, the larger the standard deviation. That is, the notch is an indicator for distinguishing mixed coal. The more notches there are, the more complex the mixture is. The Italian scheme divides the standard deviation into three levels, and the basic work is combined with the number of notches. This experiment proves that this division is also feasible for my country's commercial coal, so the parameter is used as the division mark. From the simulation results, the standard deviation is generally less than 0.5. When notches appear, the dispersion increases, especially when disconnection occurs, the standard deviation is larger. The laboratory simulation basically includes all possible types, which are generally consistent with the Italian scheme after summarization. It is worth mentioning that between the standard deviation of 0.1 and 0.2, there is a notch in the distribution map of some samples, which is different from the Italian code 1. Considering a certain probability, it is classified into code 3. The classification scheme is shown in Table 5. Table 5 Coding system code of commercial coal reflectivity distribution map
4 Comparative analysis of test results
Standard deviation
>0.1~≤0. 2
Number of notches
No notch
No notch
No notch
1 notch
2 notches
More than 2 notches
Single-seam coal
Simple mixed coal
Complex mixed coal
Mixed coal with 1 notch
Mixed coal with 2 notches
Mixed coal with more than 2 notches
There are many factors that affect the test results. Deviations in test conditions can cause systematic errors, especially between different operators and different laboratories; the level of awareness and testing skills of different operators are directly related to the accuracy of the measured values, so it is very important to unify the understanding and improve the operating technology. Here, we focus on the impact of the number of measuring points on the test results. 4.1 Selection of the number of measuring points|| tt||The principle of selecting the number of measuring points is to use as few points as possible within the allowable error range, depending on the coal grade and the degree of mixing. For low coal grades, the reflectivity distribution range is small, the standard deviation is small, and the number of measuring points is small. For high coal grades, the reflectivity distribution range is large, the standard deviation is large, and the number of measuring points is large. Similarly, the number of measuring points for single coal is small, and the number of measuring points for mixed coal is large. The regulation of the error range also follows this principle. Different types of samples are measured at different point line distances, such as 100 points, 200 points, 250 points, 300 points, 400 points, and 500 points. The results show that 100 points for single coal meet the accuracy requirements, 200 to 250 points for simple mixed coal, and 500 points for complex mixed coal to meet the accuracy requirements. Considering that most commercial coal is mixed coal, and the laboratory cannot know its properties in advance when receiving the sample, double samples are uniformly prepared. The first piece After the test, statistical analysis is performed. If the variation range of 98% of the measured values is ≤0.4%, the test can be terminated and the result calculation can be started. Otherwise, the second piece needs to be tested. After the second piece is tested, the results are statistically analyzed together. For some tests, if 250 points can meet the requirements, the second piece can be omitted. If 500 points still cannot meet the specified requirements, the point row spacing can be appropriately reduced and the number of measuring points can be increased. 4.2 Test accuracy test
The accuracy test is divided into repeatability and reproducibility.
Repeatability tests were carried out on 12 samples. From single coal to mixed coal, the error gradually increased. The difference in the average value of random reflectivity of single coal is ≤0.02%, and the difference in standard deviation is ≤0.01; the difference in the average value of reflectivity of simple mixed coal is ≤0.02%, and the difference in standard deviation is <0.02; the difference in the average value of reflectivity of complex mixed coal is ≤0.07%, and the difference in standard deviation is ≤ 0.04 The number of peaks and notches are basically the same. 548
Reproducibility test was conducted on 19 samples. The test was conducted by two laboratories, Xi'an Branch and Beijing Graduate School of China University of Mining and Technology. The difference in the average reflectance of single coal is ≤0.07%, and the difference in standard deviation is ≤0.03; the difference in the average reflectance of simple mixed coal is ≤0.13%, and the difference in standard deviation is ≤0.02. The number of peaks and notches are the same; the difference in the average reflectance of complex mixed coal is ≤0.14%, and the difference in standard deviation is ≤0.04. The number of peaks and notches are mostly the same, with some differences. Considering that the method has limited accumulated data, and the reproducibility is only conducted between two laboratories, as a national standard, the error between industries will be greater. Referring to the formula for determining precision in IS07404/5, only the repeatability range of 0 and 1 codes is given. Conclusion
This research work, through experimental verification, simulated experiments, divided commercial coal into 6 types, provided scientific identification indicators for coal trade, and made commercial coal standards one step forward in line with international advanced standards. It should be noted that the standard only gives typical graphs. In actual tests, the distribution graphs are extremely complex and varied in shape. Careful analysis and research should be conducted during identification to prevent misjudgment. When identifying peaks and concave gates, caution should be exercised, and the two parameters of standard deviation and concave should be considered comprehensively. The precision of the test still needs to be supplemented and revised in future work through continuous exploration and accumulation to form a certain scale of foundation. 54929, one or two notches, the possible code is 4. The results of samples 1~~2~~3 are the same as samples 4~5. d) Three-phase coal mixed
The difference in random reflectivity distribution of two samples is 1.3%~~1.7%, the standard deviation is greater than 0.2, there are two notches, and the possible code is 4.
e): More than one coal mixed
The difference in random reflectivity distribution of four samples is 1.3%~1.8%, the standard deviation is greater than 0.2, there are no notches or three notches, and the possible code is 2.5.
3.3 Division indicators and schemes
The above tests show that the difference in reflectivity distribution, standard deviation, and notches are effective indicators for distinguishing the properties of commercial coal. The difference in reflectivity distribution is reflected in the standard deviation. The larger the difference, the larger the standard deviation. That is, the mouth is an indicator for distinguishing mixed coal. The more notches there are, the more complex the mixture. The Italian scheme divides the standard deviation into three levels, and this basic work is combined with the use of the number of notches. This experiment proves that this division is also feasible for my country's commercial coal, so the parameter is used as the division mark. From the simulation results, the standard deviation is generally less than 0.5. When a notch appears, the dispersion increases, especially when a disconnection occurs. The laboratory simulation basically includes various types that may appear. After summarization, it is generally consistent with the Italian scheme. It is worth mentioning that between the standard deviation of 0.1 and 0.2, there are also some samples with a notch in the distribution map, which is different from the Italian code 1. Considering a certain probability, it is classified as code 3. The division scheme is shown in Table 5. Table 5 Commercial coal reflectivity distribution map coding system code
4 test results comparison analysis
Standard deviation
>0.1~≤0. 2
Number of notches
No notch
No notch
No notch
1 notch
2 notches
More than 2 notches
Single-seam coal
Simple mixed coal
Complex mixed coal
Mixed coal with 1 notch
Mixed coal with 2 notches
Mixed coal with more than 2 notches
There are many factors that affect the test results. Deviations in test conditions can cause systematic errors, especially between different operators and different laboratories; the level of awareness and testing skills of different operators are directly related to the accuracy of the measured values, so it is very important to unify the understanding and improve the operating technology. Here, we focus on the impact of the number of measuring points on the test results. 4.1 Selection of the number of measuring points|| tt||The principle of selecting the number of measuring points is to use as few points as possible within the allowable error range, depending on the coal grade and the degree of mixing. For low coal grades, the reflectivity distribution range is small, the standard deviation is small, and the number of measuring points is small. For high coal grades, the reflectivity distribution range is large, the standard deviation is large, and the number of measuring points is large. Similarly, the number of measuring points for single coal is small, and the number of measuring points for mixed coal is large. The regulation of the error range also follows this principle. Different types of samples are measured at different point line distances, such as 100 points, 200 points, 250 points, 300 points, 400 points, and 500 points. The results show that 100 points for single coal meet the accuracy requirements, 200 to 250 points for simple mixed coal, and 500 points for complex mixed coal to meet the accuracy requirements. Considering that most commercial coal is mixed coal, and the laboratory cannot know its properties in advance when receiving the sample, double samples are uniformly prepared. The first piece After the test, statistical analysis is performed. If the variation range of 98% of the measured values is ≤0.4%, the test can be terminated and the result calculation can be started. Otherwise, the second piece needs to be tested. After the second piece is tested, the results are statistically analyzed together. For some tests, if 250 points can meet the requirements, the second piece can be omitted. If 500 points still cannot meet the specified requirements, the point row spacing can be appropriately reduced and the number of measuring points can be increased. 4.2 Test accuracy test
The accuracy test is divided into repeatability and reproducibility.
Repeatability tests were carried out on 12 samples. From single coal to mixed coal, the error gradually increased. The difference in the average value of random reflectivity of single coal is ≤0.02%, and the difference in standard deviation is ≤0.01; the difference in the average value of reflectivity of simple mixed coal is ≤0.02%, and the difference in standard deviation is <0.02; the difference in the average value of reflectivity of complex mixed coal is ≤0.07%, and the difference in standard deviation is ≤ 0.04 The number of peaks and notches are basically the same. 548
Reproducibility test was conducted on 19 samples. The test was conducted by two laboratories, Xi'an Branch and Beijing Graduate School of China University of Mining and Technology. The difference in the average reflectance of single coal is ≤0.07%, and the difference in standard deviation is ≤0.03; the difference in the average reflectance of simple mixed coal is ≤0.13%, and the difference in standard deviation is ≤0.02. The number of peaks and notches are the same; the difference in the average reflectance of complex mixed coal is ≤0.14%, and the difference in standard deviation is ≤0.04. The number of peaks and notches are mostly the same, with some differences. Considering that the method has limited accumulated data, and the reproducibility is only conducted between two laboratories, as a national standard, the error between industries will be greater. Referring to the formula for determining precision in IS07404/5, only the repeatability range of 0 and 1 codes is given. Conclusion
This research work, through experimental verification, simulated experiments, divided commercial coal into 6 types, provided scientific identification indicators for coal trade, and made commercial coal standards one step forward in line with international advanced standards. It should be noted that the standard only gives typical graphs. In actual tests, the distribution graphs are extremely complex and varied in shape. Careful analysis and research should be conducted during identification to prevent misjudgment. When identifying peaks and concave gates, caution should be exercised, and the two parameters of standard deviation and concave should be considered comprehensively. The precision of the test still needs to be supplemented and revised in future work through continuous exploration and accumulation to form a certain scale of foundation. 54929, one or two notches, the possible code is 4. The results of samples 1~~2~~3 are the same as samples 4~5. d) Three-phase coal mixed
The difference in random reflectivity distribution of two samples is 1.3%~~1.7%, the standard deviation is greater than 0.2, there are two notches, and the possible code is 4.
e): More than one coal mixed
The difference in random reflectivity distribution of four samples is 1.3%~1.8%, the standard deviation is greater than 0.2, there are no notches or three notches, and the possible code is 2.5.
3.3 Division indicators and schemes
The above tests show that the difference in reflectivity distribution, standard deviation, and notches are effective indicators for distinguishing the properties of commercial coal. The difference in reflectivity distribution is reflected in the standard deviation. The larger the difference, the larger the standard deviation. That is, the mouth is an indicator for distinguishing mixed coal. The more notches there are, the more complex the mixture. The Italian scheme divides the standard deviation into three levels, and this basic work is combined with the use of the number of notches. This experiment proves that this division is also feasible for my country's commercial coal, so the parameter is used as the division mark. From the simulation results, the standard deviation is generally less than 0.5. When a notch appears, the dispersion increases, especially when a disconnection occurs. The laboratory simulation basically includes various types that may appear. After summarization, it is generally consistent with the Italian scheme. It is worth mentioning that between the standard deviation of 0.1 and 0.2, there are also some samples with a notch in the distribution map, which is different from the Italian code 1. Considering a certain probability, it is classified as code 3. The division scheme is shown in Table 5. Table 5 Commercial coal reflectivity distribution map coding system code
4 test results comparison analysis
Standard deviation
>0.1~≤0. 2
Number of notches
No notch
No notch
No notch
1 notch
2 notches
More than 2 notches
Single-seam coal
Simple mixed coal
Complex mixed coal
Mixed coal with 1 notch
Mixed coal with 2 notches
Mixed coal with more than 2 notches
There are many factors that affect the test results. Deviations in test conditions can cause systematic errors, especially between different operators and different laboratories; the level of awareness and testing skills of different operators are directly related to the accuracy of the measured values, so it is very important to unify the understanding and improve the operating technology. Here, we focus on the impact of the number of measuring points on the test results. 4.1 Selection of the number of measuring points|| tt||The principle of selecting the number of measuring points is to use as few points as possible within the allowable error range, depending on the coal grade and the degree of mixing. For low coal grades, the reflectivity distribution range is small, the standard deviation is small, and the number of measuring points is small. For high coal grades, the reflectivity distribution range is large, the standard deviation is large, and the number of measuring points is large. Similarly, the number of measuring points for single coal is small, and the number of measuring points for mixed coal is large. The regulation of the error range also follows this principle. Different types of samples are measured at different point line distances, such as 100 points, 200 points, 250 points, 300 points, 400 points, and 500 points. The results show that 100 points for single coal meet the accuracy requirements, 200 to 250 points for simple mixed coal, and 500 points for complex mixed coal to meet the accuracy requirements. Considering that most commercial coal is mixed coal, and the laboratory cannot know its properties in advance when receiving the sample, double samples are uniformly prepared. The first piece After the test, statistical analysis is performed. If the variation range of 98% of the measured values is ≤0.4%, the test can be terminated and the result calculation can be started. Otherwise, the second piece needs to be tested. After the second piece is tested, the results are statistically analyzed together. For some tests, if 250 points can meet the requirements, the second piece can be omitted. If 500 points still cannot meet the specified requirements, the point row spacing can be appropriately reduced and the number of measuring points can be increased. 4.2 Test accuracy test
The accuracy test is divided into repeatability and reproducibility.
Repeatability tests were carried out on 12 samples. From single coal to mixed coal, the error gradually increased. The difference in the average value of random reflectivity of single coal is ≤0.02%, and the difference in standard deviation is ≤0.01; the difference in the average value of reflectivity of simple mixed coal is ≤0.02%, and the difference in standard deviation is <0.02; the difference in the average value of reflectivity of complex mixed coal is ≤0.07%, and the difference in standard deviation is ≤ 0.04 The number of peaks and notches are basically the same. 548
Reproducibility test was conducted on 19 samples. The test was conducted by two laboratories, Xi'an Branch and Beijing Graduate School of China University of Mining and Technology. The difference in the average reflectance of single coal is ≤0.07%, and the difference in standard deviation is ≤0.03; the difference in the average reflectance of simple mixed coal is ≤0.13%, and the difference in standard deviation is ≤0.02. The number of peaks and notches are the same; the difference in the average reflectance of complex mixed coal is ≤0.14%, and the difference in standard deviation is ≤0.04. The number of peaks and notches are mostly the same, with some differences. Considering that the method has limited accumulated data, and the reproducibility is only conducted between two laboratories, as a national standard, the error between industries will be greater. Referring to the formula for determining precision in IS07404/5, only the repeatability range of 0 and 1 codes is given. Conclusion
This research work, through experimental verification, simulated experiments, divided commercial coal into 6 types, provided scientific identification indicators for coal trade, and made commercial coal standards one step forward in line with international advanced standards. It should be noted that the standard only gives typical graphs. In actual tests, the distribution graphs are extremely complex and varied in shape. Careful analysis and research should be conducted during identification to prevent misjudgment. When identifying peaks and concave gates, caution should be exercised, and the two parameters of standard deviation and concave should be considered comprehensively. The precision of the test still needs to be supplemented and revised in future work through continuous exploration and accumulation to form a certain scale of foundation. 5494%, the test can be ended and the result calculation can be started. Otherwise, the second piece needs to be tested. After the second piece is tested, the results are statistically analyzed together. For some tests, such as 250 points, the second piece can be omitted if it can meet the requirements. If 500 points still cannot meet the specified requirements, the point spacing can be appropriately reduced and the number of test points can be increased. 4.2 Test accuracy test
The accuracy test is divided into repeatability and reproducibility.
Repeatability tests were conducted on 12 samples. From single coal to mixed coal, the error gradually increased. The difference in the average value of random reflectivity of single coal is ≤0.02%, and the difference in standard deviation is ≤0.01; the difference in the average value of reflectivity of simple mixed coal is ≤0.02%, and the difference in standard deviation is <0.02; the difference in the average value of reflectivity of complex mixed coal is ≤0.07%, and the difference in standard deviation is ≤0.04. The number of peaks and notches is basically the same. 548
Reproducibility test was conducted on 19 samples. The test was conducted by two laboratories, Xi'an Branch and Beijing Graduate School of China University of Mining and Technology. The difference of single coal reflectivity average value was ≤0.07%, and the difference of standard deviation was ≤0.03; the difference of simple mixed coal reflectivity average value was ≤0.13%, and the difference of standard deviation was ≤0.02. The number of peaks and notches was the same; the difference of complex mixed coal reflectivity average value was ≤0.14%, and the difference of standard deviation was ≤0.04. The number of peaks and notches was mostly the same, but some were different.
Considering that the data accumulated by this method is limited, and the reproducibility is only conducted between two laboratories, as a national standard, the error between industries will be greater. Referring to the formula for determining precision in IS07404/5, only the repeatability range of 0 and 1 codes is given. Conclusion
This research work, through experimental verification, simulated experiments, divided commercial coal into 6 types, provided scientific identification indicators for coal trade, and made the commercial coal standard one step forward in aligning with international advanced standards. It should be noted that the standard only gives a typical spectrum. In actual testing, the distribution diagram is extremely complex and varied. Careful analysis and research should be conducted during the judgment to prevent misjudgment. The peak and concave gate should be identified with caution, and the two parameters of standard deviation and concave gate should be considered comprehensively. The precision of the test still needs to be supplemented and revised in future work through continuous exploration and accumulation to form a certain scale of foundation.4%, the test can be ended and the result calculation can be started. Otherwise, the second piece needs to be tested. After the second piece is tested, the results are statistically analyzed together. For some tests, such as 250 points, the second piece can be omitted if it can meet the requirements. If 500 points still cannot meet the specified requirements, the point spacing can be appropriately reduced and the number of test points can be increased. 4.2 Test accuracy test
The accuracy test is divided into repeatability and reproducibility.
Repeatability tests were conducted on 12 samples. From single coal to mixed coal, the error gradually increased. The difference in the average value of random reflectivity of single coal is ≤0.02%, and the difference in standard deviation is ≤0.01; the difference in the average value of reflectivity of simple mixed coal is ≤0.02%, and the difference in standard deviation is <0.02; the difference in the average value of reflectivity of complex mixed coal is ≤0.07%, and the difference in standard deviation is ≤0.04. The number of peaks and notches is basically the same. 548
Reproducibility test was conducted on 19 samples. The test was conducted by two laboratories, Xi'an Branch and Beijing Graduate School of China University of Mining and Technology. The difference of single coal reflectivity average value was ≤0.07%, and the difference of standard deviation was ≤0.03; the difference of simple mixed coal reflectivity average value was ≤0.13%, and the difference of standard deviation was ≤0.02. The number of peaks and notches was the same; the difference of complex mixed coal reflectivity average value was ≤0.14%, and the difference of standard deviation was ≤0.04. The number of peaks and notches was mostly the same, but some were different.
Considering that the data accumulated by this method is limited, and the reproducibility is only conducted between two laboratories, as a national standard, the error between industries will be greater. Referring to the formula for determining precision in IS07404/5, only the repeatability range of 0 and 1 codes is given. Conclusion
This research work, through experimental verification, simulated experiments, divided commercial coal into 6 types, provided scientific identification indicators for coal trade, and made the commercial coal standard one step forward in aligning with international advanced standards. It should be noted that the standard only gives a typical spectrum. In actual testing, the distribution diagram is extremely complex and varied. Careful analysis and research should be conducted during the judgment to prevent misjudgment. The peak and concave gate should be identified with caution, and the two parameters of standard deviation and concave gate should be considered comprehensively. The precision of the test still needs to be supplemented and revised in future work through continuous exploration and accumulation to form a certain scale of foundation.
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