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National Standard of the People's Republic of ChinaWww.bzxZ.net
Preparation of coal sample
This standard uses ISO1988-1975 "Preparation of coal samples for general analysis of hard coal".
1 Subject content and scope of application
GB474-1996
Replaces GB474:83
Sampling" Chapter 8 "Preparation of coal samples for total moisture determination" and Chapter 9 "This standard specifies the general principles, facilities, equipment, tools, reagents and operating procedures for the preparation of coal samples. This standard is applicable to the preparation of commercial coal samples, coal seam coal samples, production coal samples, production inspection coal samples, coal core coal samples and other coal samples of various coals into coal samples for general analysis or special analysis. 2 Reference Standards GB475 Commercial Coal Sampling Method Determination Method of Total Moisture in Coal Industrial Analysis Method of Coal Determination Method of True Density of Coal 3 General Principles of Sample Preparation 3.1 The purpose of sample preparation is to prepare the collected coal samples into coal samples for analysis (test) that can represent the original coal samples through procedures such as crushing, mixing and reduction. The design of sample preparation and scheme shall be based on obtaining sufficiently small sample preparation variance and not too large sample retention amount. 3.2 The total accuracy of coal sample preparation and analysis is 0.05A, and there is no systematic deviation. A is the total precision of sampling, sample preparation and analysis (see G3475). 1 The value is specified in Appendix A1. 3.3 The precision of coal sample preparation shall be tested in accordance with Appendix A in the following cases: when a new reduction machine and a combined machine for reduction of broken coal are used; a.
b. when there is doubt about the precision of coal sample preparation: other times when it is considered necessary to test the precision of coal sample preparation. 4 Reagents
4.1 Zinc chloride (HG/T2323): industrial product. 4.2 Silver nitrate solution: 1% aqueous solution. Weigh about 1g of silver nitrate (GB 670). Dissolve in 100mL of water and add a few drops of nitric acid (GB/T G26). Store in a dark bottle.
5 Facilities, equipment and tools
5.1 The coal sample room (including rooms for sample preparation, sampling, drying, ash reduction, etc.) should be spacious and bright, and not affected by wind, rain and external dust. Dust-proof equipment should be available.
The sample preparation room should have a cement floor. For the reduction and partition of the heap, a steel plate with a thickness of more than 6 mm needs to be laid on the cement floor. Approved by the State Administration of Technical Supervision on 199606-14
Implementation on 1997-02-01
GB 474-1996
The room where the coal samples are stored should not have heat sources, strong light exposure, or any chemicals. 5.2 The crushers suitable for sample preparation are jaw crushers, hammer crushers, roller crushers, steel rod (ball) mills, other sealed grinders, and various reduction machines and combined crushing and reduction machines without system deviation and with accuracy that meets the requirements. 5.3 Steel plates and steel whips for manually grinding coal samples. 5.4 Dividers of different specifications (as shown in Figure 1), the width of the grid slots of the divider is 2.5~~3 times the maximum particle size of the coal sample, but not less than 5 mm. The number of grid slots on both sides should be equal, the width of each grid slot should be the same, and the slope of the grid slot equal slope should not be less than 60°. 5.5 Cross-section sample plate, flat iron titanium, iron shovel, galvanized iron plate or porcelain plate, brush, platform scale, tray balance, camel scale, cleaning equipment and magnet.
Schematic diagram of the two-partitioner
5.6 Tight containers for storing coal samples with full moisture content and coal samples for analysis and testing. 5.7 Vibrating screen and square hole sieves with apertures of 25, 13, 6, 3, 1 and 0.2 mm and other apertures, 3 mm round hole sieve. 5.8 Blowing drying box with controlled temperature at 45-50℃. 5.9 Cloth bag or suction filter and nylon filter cloth for ash reduction. 5.10 The receiving spoon for scooping coal samples is made of copper wire mesh with mesh size of 0.5mm×0.5mm or nylon cloth with similar mesh size. The diameter of the scoop should be less than 1/2 of the diameter of the ash reduction barrel.
5.11 The barrels for reducing ash and storing heavy liquid are made of galvanized iron plate, plastic plate or other anti-corrosion materials. 5.12 One set of liquid relative density meter, with a measuring range of 1.00~-2.00 and a minimum graduation value of 0.01.6 Preparation of coal samples
6.1 After receiving the coal sample, it should be checked item by item according to the sample label, and the coal type, variety, particle size, sampling location, packaging, coal sample quality, sample collection and preparation time should be recorded in detail in the coal sample record book and numbered. If it is a commercial coal sample, the vehicle number and shipping tonnage should also be registered. 6.2 The coal sample should be prepared into air-dried coal sample in time according to the preparation procedure specified in this standard (see Figure 2). Or it can be made into a laboratory coal sample of appropriate particle size first. If the moisture content is too high, it will affect further crushing and reduction. It should be properly dried at a temperature below 50 in advance. 6.3 Except for the use of combined crushing and reducing machines, coal samples should be crushed until all coal samples pass through the corresponding sieves, and then reduced in reverse. Coal samples with a particle size greater than 25 mm are not allowed to be reduced without being crushed.
GB 474--1996
6.4 The preparation of coal samples can be completed at one time or processed in parts. If divided into several parts, each part should be reduced to produce coal samples in the same proportion, and then the coal samples of each part should be combined as a coal sample. 6.5 Before and after each crushing and reducing, the machine and the equipment should be cleaned thoroughly. Sample preparation personnel should wear special shoes during the process of preparing coal samples to avoid contaminating the coal samples.
For sealed crushers (such as hammer crushers) and combined crushing and reducing machines that are not easy to clean, when they are only used to process a large number of coal samples of a single variety, before processing each coal sample, the coal used to take the coal sample can be "flushed" through the machine, and the "flushing" coal can be discarded before processing the coal sample. After the burial, the machine should be repeatedly started and stopped several times to remove the retained coal samples. 6.6 For the reduction of coal samples, except for those with high moisture content that cannot be reduced by machine, a splitter and a reduction machine should be used as much as possible to reduce the reduction error.
6.7 The corresponding relationship between the sample mass and particle size after reduction is shown in Figure 2. For coal samples with a particle size of less than 3mm, after being reduced to 3.75kg, if all of them pass through a 3mm round hole sieve, a splitter can be used to directly reduce the sample. Not less than 100g and not less than 500g are used to prepare coal samples for analysis and as storage and inspection samples respectively. The preparation of coal samples used in test items H with special particle size requirements should be in accordance with the provisions of this standard, and the corresponding equipment should be used at the corresponding stages. When crushing, the method of step-by-step crushing should be adopted. That is, the crushing port of the crusher should be adjusted so that only particles larger than the required particle size are crushed, and particles smaller than the required particle size are no longer crushed repeatedly. 6.8 The reduction machine must be inspected before use. The coal samples of the inspection and reduction machine, including the retained samples and the discarded samples, must be further reduced by using a divider.
6.9 Use a divider to reduce the coal samples. No mixing is required before reduction. When feeding, the dustpan should be tilted to the side and swing back and forth along the entire length of the divider so that the coal samples pass through the divider more evenly. After reduction, take any coal sample from the side. 6.10 The cone quartering method is to reduce the coal sample by shoveling the crushed and screened coal sample with a flat iron shovel to pile it into a cone, and then shovel it from the diagonal bottom of the two sides of the coal sample pile alternately to pile it into another cone. The coal sample shoveled by each shovel should not be too much, and it should be dropped on the top of the new chain two or three times so that it falls evenly around the new cone. Repeat the mixing process once, and then evenly spread the coal sample from the top of the coal sample pile from the center to the periphery (when there are more coal samples) or press it flat (when there are fewer coal samples) into a flat body of appropriate thickness. Place the cross sample dividing plate in the middle of the flat fan body, press down and pull the bottom, the coal sample is divided into four equal fan-shaped bodies, discard the two opposite fan-shaped bodies, and prepare the general analysis coal sample or other coal samples of appropriate particle size according to the particle size and mass limits specified in the procedure of Figure 2 for the remaining two fan-shaped bodies. After the coal sample is gradually crushed and reduced, the particle size and mass gradually become smaller. The shovel used for mixing coal samples should be appropriately reduced or the amount of coal sample shoveled each time should be reduced accordingly.
6.11 Before crushing into a coal sample of 0.2mtn, use a magnet to absorb the iron filings in the coal sample, and then crush it until all of it passes through a sieve with an aperture of 0.2mm, and make it After reaching air-dry state, put it into coal sample bottle (the amount of coal sample put in should not exceed 3/4 of the narrow volume of coal sample bottle, so as to facilitate mixing when using). Send it to laboratory for testing. The air-drying method is as follows: put the coal sample into a plate, spread it into a uniform thin layer, and dry it at a temperature not exceeding 50℃. If the mass change of the coal sample does not exceed 0.1% after continuous drying for 1 hour, it reaches air-dry state. Air drying can also be carried out before the coal sample is crushed to 0.2mm.
6.12 Coal core sample can be reduced to 100g from coal sample less than 3mm. Then it is prepared into coal sample for analysis according to the provisions of 6.11. 6.13 Preparation of coal sample with total moisture content
6.13.1 Coal sample for determining total moisture content can be prepared from coal sample special for moisture content, or it can be taken in the process of preparing general coal sample for analysis: 6.13.2 In addition to using a reducer that can reduce a sufficient number of full-moisture coal samples at one time, after the coal sample is crushed to the specified particle size, it is slightly mixed, flattened, and immediately reduced using the nine-point method (point arrangement as shown in Figure 3), placed in a coal sample bottle and sealed tightly (the sample volume must not exceed 3/1 of the volume of the coal sample bottle), weighed, labeled, and quickly sent to the laboratory for total moisture determination. For details on the particle size and mass of full-moisture coal samples, see GB211. The preparation of full-moisture coal samples should be rapid.
25mm coal sample
Sieve hole 25 mn1
2a60kz
GB 474-1996
Sieve hole 13at
Full moisture coal stack
Full moisture coal sample
Gum
Sieve hole 3mm
ca3 r5 kg
Coal sample before ash reduction
Coal sample for storage and inspection when using a binary divider for reduction (20.5 kc) Sieve hole 1mm
Coal sample for storage and inspection (≥0 5kg)
Father one by one crack
——Combined
Sieve lead, 0. 2 aur
Analysis of coal sample
Figure 2 Preparation procedure of coal sample
Daily decoration
GB474-1996
0-Center of coal sample pile r-Parallel diameter of coal sample pileFigure 3 Schematic diagram of nine-point method for taking total moisture coal sample6.14 In addition to labeling the container, coal sample labels should be placed in the container and sealed. The label format can refer to Table 1Table 1Label
Analysis of coal sample reduction
Sample number
Name of coal mine
Type of coal sample
Delivery unit
Sample delivery date
Sample preparation period
Analysis test items
6.14.1 The reduction of general storage coal samples is shown in Figure 2. If there are special requirements, the particle size and quality of the storage coal samples can be determined according to the needs. 6.14.2 The coal samples for commercial coal inspection shall be kept for 2 months from the date of reporting the results for re-inspection. 6.14.3 The storage time of production inspection coal samples shall be determined by the relevant coal quality inspection department. 6.14.4 The storage time of other analytical test coal samples shall be determined according to the needs. 7 Ash reduction of samples
7.1 When the coal with ash content greater than 10% needs to be analyzed and tested with floating coal, the raw coal samples with a particle size less than 3 tm shall be put into heavy liquid to store the ash.
GB 474
7.2 The heavy liquid for ash reduction is an aqueous solution of zinc nitride. The relative density of heavy liquid is specified as follows: 7.2.1 Bituminous coal and lignite are generally deashed with heavy liquid of relative density 1.4. If the ash content is still less than 10% after deashing with the heavy liquid, another coal sample should be taken and deashed with heavy liquid of relative density 1.35. If the ash content is still greater than 10%, no more deashing is required. 7.2.2 The relative density of deashed heavy liquid for anthracite (deashed relative density) can be calculated according to the relationship between the dry basis true relative density (TRD), the dry mineral-free basis true relative density (TRD) amm and the decimal ash content (Aa) of the raw coal sample. (TRD) a-(TRD) dmm+0.01Aa
The calculation steps of deashed relative density are as follows
(1)
a. First, determine the moisture content, ash content and true relative density of the raw coal according to GB212 and GB217 respectively. The dry basis relative density of the raw coal is calculated by formula (2) using the dry basis ash content and dry basis relative density: (TRD)an(TRD>—(. 01A. --
h. The dry basis relative density of the floating coal with an ash content of 8% (TRD)td is calculated based on the dry basis relative density of the raw coal. (TRD): = (TRD)mmr+0. 01X8
Round the second decimal place of the calculated (TRD%), a value to 0 or 5 (i.e. 0.04 and below are all taken as 0.00; 0.09-0.05 are all taken as 0.05), which is the relative density after ash reduction. See Table 2 for the preparation of heavy liquid.
Table 2 Relative density of heavy liquid and relative concentration of zinc chloride in heavy liquid
7.3 Ash reduction operation steps:
Concentration of zinc ammonia in aqueous solution·g/1
7.3.1 Before ash reduction of coal sample, First, use a relative density meter to measure the relative density of the heavy liquid to make it reach the required value. 7.3.2 First, add a small amount of heavy liquid to the coal sample with a particle size less than 3mm, stir, and then add enough heavy liquid after it is completely wetted, stir it thoroughly, and then leave it for at least 5 minutes. Use a scoop to pick up the floating coal on the heavy liquid along the liquid surface, put it in a cloth bag or a filter, and then use water to wash the zinc chloride on the coal particles. For coal with a low coalification process (such as lignite and long flame coal), first use cold water to rinse off the zinc chloride on the surface, and then use 50-60℃ hot water to wash it twice, at least 5 minutes each time. Add i, and finally rinse with cold water. The sign that the zinc chloride on the coal particles has been washed clean is: use test tubes to collect the same volume of clean water and water used to wash the coal, add 2 drops of 1% nitric acid solution to each test tube, and the turbidity is the same. 7.3.3 Pour the floating coal with reduced ash into a galvanized iron plate or other stainless metal shallow plate (the thickness of the coal sample shall not exceed 5mm), dry it in a constant temperature box at 45-50℃, and then prepare the coal sample according to the relevant regulations for raw coal sample preparation according to the test requirements. GB 474—1996
Appendix A
Test method for the precision of the whole process of preparing coal samples (supplement)
The purpose of this method is to test whether the difference between the measured value and 0.05A is significant. A1First, the coal sample is mixed and divided into two parts (or reduced into two parts), and then each part is treated as a separate sample to obtain two analytical coal samples. The moisture and ash content of the two analytical coal samples are tested according to GB212, and the dry basis ash content is calculated. The difference between the dry basis ash content of the two (h) is calculated.
Make 20 coal samples of the same coal. The absolute value of 10 consecutive values is a group (grouping cannot be selected), and the average value of each group is calculated. A2 If the average value of two consecutive groups is less than 0.37A, it is considered that the precision of coal sample preparation meets the requirements. If there is: - the average value of the group is too large to be 0 .37A, it means that the sample preparation variance is too large and the cause needs to be checked and improvement measures taken to meet the precision requirements (see Table A1). Table A1 Sampling, sample preparation and analysis total precision Raw coal, screened coal
Lower ash content 20%
Upper 1710X East content
But not less than = 1%
(absolute value)
Lower base ash content > 20%
±2 pulp || tt||(Value)
Appendix B
Test method for dividing machine
(Supplement)
(Absolute value)
Other media
(Including medium media)
(Absolute value)
The purpose of this method is to test whether the precision of dividing machine (including crushing dividing machine) meets the requirement of 0.05A\ and whether there is any system error in the dividing machine.
B1 Precision test
B1.1 The small amount of coal sample and the large amount of coal sample separated from the separator are separated by the separator, and prepared into air-dried coal samples. According to (GB212), the moisture and ash content are tested, and the basic ash content is calculated, and the difference in the basic ash content between the two is calculated (h). At least 20 samples of the same coal are prepared. The absolute value of 10 consecutive 1 values is a group (grouping cannot be selected), and the average value of the obtained group is calculated. If the separator can separate more than 2 small amounts of coal samples at the same time, the basic ash content between each coal sample and the discarded sample is calculated. B1.2 If the average values of two consecutive groups are less than 0.37A, the coal sample preparation precision meets the requirements. If the average value of the right group is greater than 0.37A, it does not meet the requirements.
B2 Test of systematic deviation
B2.1 Substitute the difference d (with positive and negative signs) of the ten-base ash content of at least 20 coal samples calculated in Article B1.1 of this Appendix into formulas (B1) and (B32) to calculate the average difference 7 and variance Va: Where: n
The number of differences.
GB 474—1996
Edz_ (E)?
Substitute 7, and n into formula (B3) to calculate the calculated value t. n
From Table B1 (t value table), find the t value with degree of freedom n-1 and significance level of 0.05. If >, it is considered that the reducer has a systematic deviation, and its estimated value is d. Table B1t value table
F by degree
Additional notes:
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. White degree
This standard is drafted and interpreted by the Beijing Coal Chemistry Research Institute of the China Coal Research Institute. The main drafters of this standard are Er Xianying and Duan Yunlong. This standard was first issued in October 1964. ta re
（2）It is considered that the reducer has a systematic deviation, and its estimated value is d. Table B1t value table
F by degree
Additional notes:
The 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. White out degree
This standard is drafted and interpreted by the Beijing Coal Chemistry Research Institute of the China Coal Research Institute. The main drafters of this standard are Er Xianying and Duan Yunlong. This standard was first issued in October 1964. ta re
(2)
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