MT/T 707-1997 Spectroscopic oxygen absorption method for identification of spontaneous combustion tendency of coal
Some standard content:
MT/T 707—1997
Foreword
In my country, the ignition temperature method has long been used to classify the spontaneous combustion tendency of coal. However, this method is not only cumbersome to operate, but also often has great differences with the actual situation, and there is no corresponding standard. During the "Seventh Five-Year Plan" period, my country began to conduct research on the chromatographic oxygen absorption identification method for the spontaneous combustion tendency of coal, and this method has been widely used in my country. However, for a long period of time, there was a phenomenon of using these two test methods at the same time, which caused the management and application of this important indicator to be in a relatively chaotic state, bringing great inconvenience to the safety management of coal mines. For this reason, the Implementation Instructions of the "Coal Mine Safety Regulations" (1992 Edition) stipulates that the chromatographic oxygen absorption identification method shall be used for the identification of the spontaneous combustion tendency of coal.
The classification index of coal spontaneous combustion tendency was initially determined on the basis of the test of more than 300 coal samples, in connection with the actual spontaneous combustion of these coal seams in mine production, after a large amount of data analysis and processing. Later, after years of application practice and collection of actual application data on site, the data volume of this index reached more than 1,000. After analysis, it was found that the classification index set in the initial plan was too high, resulting in the number of Class 1 coal seams that were prone to spontaneous combustion determined by this index being less than the number of coal seams with more serious spontaneous combustion in actual production on site. After extensively soliciting opinions from on-site users and after a large amount of data processing, the lower limit of the oxygen absorption index of Class 1 coal seams that are prone to spontaneous combustion was reduced to 0.71.
Appendix A, Appendix B, and Appendix C of this standard are all appendices to the standard. This standard was proposed by the Science and Technology Education Department of the Ministry of Coal Industry. This standard is technically managed by the Coal Mine Safety Standardization Technical Committee of the Ministry of Coal Industry. The drafting unit of this standard: Fushun Branch of the China Coal Research Institute. The main drafter of this standard: Qian Guoyin.
This standard is entrusted to Fushun Branch of China Coal Research Institute for interpretation. 585
1 Scope
Coal Industry Standard of the People's Republic of China
Method for identifying tendency of coal to spontaneous combustion by oxygen adsorption with chromatograph
This standard specifies the method for identifying tendency of coal to spontaneous combustion by oxygen adsorption with chromatograph, classification indexes and classification grades. This standard is applicable to the identification of spontaneous combustion tendency of lignite, bituminous coal and anthracite (containing high sulfur coal). 2 Cited Standards
MT/T 707 -- 1997
The provisions contained in the following standards constitute the provisions of this standard through reference in this standard. When this standard is published, the versions shown are valid. All standards will be revised, and parties using this standard should explore the possibility of using the latest version of the following standards. GB/T212—91 Coal industry analysis method
GB/T 214--832
Determination method of total sulfur in coal
GB/T 217--81
Determination method of true specific gravity of coal
GB/T474—83 Preparation method of coal sample
GB 482—1995
Method for taking coal samples from coal seams
GB/T4946-—85 Terminology of gas chromatography
MT/T708-—1997 Technical conditions for coal spontaneous combustion tester (to be announced) Coal Mine Safety Regulations 1992-10-22 Ministry of Energy of the People's Republic of China 3 Definitions
This standard adopts the following definitions.
3.1 Coal spontaneous combustion tendency The intrinsic property of coal's oxidation ability at room temperature. 3.2 Chromatographic method of fluid oxygen adsorption A method that uses thermal conductivity dual-path gas chromatography analysis and detection technology to determine the adsorption capacity of coal for fluid oxygen, and characterizes the oxidative self-ignition performance of coal by the amount of oxygen adsorption.
3.3 Quantity of oxygen adsorption of coal The amount of fluid oxygen adsorbed by each gram of dry coal at normal temperature and pressure (the main indicator for judging the self-ignition tendency of coal seams). 4 Instruments and auxiliary equipment
4.1 Instruments and equipment
Coal self-ignition tester.
4.2 Auxiliary equipment and other materials
Approved by the Ministry of Coal Industry of the People's Republic of China on December 30, 1997 586
Implemented on July 1, 1998
a) Analytical balance: accuracy 0.0001g;
b) Coal sample crusher;
c) Standard analytical sieve;
d) Special standard sample tube (see Appendix C for structure); MT/T 707 --- 1997
e) Cylinder nitrogen and oxygen: purity requirements are both above 99.99%. 5 Preparation before determination
5.1 Collection of coal samples
Collect coal samples from coal seams in accordance with GB482, and at the same time, they should meet the requirements of Appendix A. 5.2 Preparation of coal samples
In accordance with the relevant provisions of GB/T474, they should also meet the requirements of Appendix B. 5.3 Management of coal samples
The raw coal samples sent for identification and the prepared analytical coal samples shall be sealed and stored, and shall not be discarded or otherwise handled until half a year after the identification report is issued. 5.4 Determination of the following parameters
a) Industrial analysis of coal shall be carried out in accordance with GB/T212. b) Determination of total sulfur in coal shall be carried out in accordance with GB/T214. c) Determination of true specific gravity of coal shall be carried out in accordance with GB/T217. 5.5 Determination of instrument constants
Under the conditions consistent with the determination of oxygen absorption (see the following 6 items), the instrument constant is determined by subtracting the dead volume of the sample tube by the side gas path.
The instrument constant K is calculated according to formula (1):
Where: K
Instrument constant, min/mV·s;
Ratio of oxygen partial pressure to atmospheric pressure,
Volume of sample tube, cm;
273P.
1.0133×105T
S. — Area corresponding to the volume of the sample tube V., mV·s; R carrier gas flow rate, cm\min;
P. — Atmospheric pressure under experimental conditions, Pa,
T-- Column box temperature under experimental conditions, K. 5.6 Pretreatment of coal samples
· (1)
Weigh 1.0000g of the prepared coal sample and put it into a standard sample tube, pass nitrogen (flow rate 30cm/min), and treat it at a column box temperature of 105℃ for 1.5h.
6 Determination and calculation of oxygen absorption
This method uses the instrument constant method to determine the oxygen absorption of coal. The treated coal sample is adsorbed with oxygen for 20 minutes at a column box temperature of 30°C, a thermal conductivity temperature of 80-100°C, a carrier gas nitrogen flow rate of 30±0.5 cm2/min, and an adsorption gas oxygen flow rate of 20±0.5 cm/min, and the desorption peak area St is measured; the coal sample is poured out, and under the same conditions, the same sample tube is empty and adsorbed with oxygen for 5 minutes, and the desorption peak area S2 is measured; S1, S2 and other measured parameters of the test conditions are substituted into formula (2) to calculate the oxygen absorption value. 587
Vd = K. Rci(S.
MT/T 707— 1997
αzRc2
Wherein: Va—oxygen absorption of coal, cm/g dry coal; K-instrument constant, min/mV·s;
Rc—real tube carrier gas flow, cm\/min;
—empty tube carrier gas flow, cm/min;
× S,(1
αThe ratio of partial pressure of oxygen in a full tube to atmospheric pressure; Q2
The ratio of partial pressure of oxygen in an empty tube to atmospheric pressure; S,-desorption peak area in a full tube, mV·s;
S,----desorption peak area in an empty tube, mV·s;
G-weight of coal sample, g;
True specific gravity of coal;
-volume of sample tube (standard state), cm2; Vs
W-total moisture content of coal sample, %.
7Classification of coal spontaneous combustion tendency grades
drrn ·Vs
(1 --- W.).G
..0*...( 2 )
The oxygen absorption per gram of dry coal at normal temperature (30℃) and normal pressure (1.0133×10\Pa) is used as the main index for classification. The spontaneous combustion tendency of coal is classified according to Table 1 and Table 2.
Table 1 Classification of spontaneous combustion tendency of lignite and bituminous coal Spontaneous combustion tendency grade
Spontaneous combustion tendency grade
1) Contains combustible volatile matter ≤18.0%.
Allowable error
Spontaneous combustion tendency
Easy to spontaneously ignite
Not easy to spontaneously ignite
Table 2 Classification table of spontaneous combustion tendency of "high sulfur coal and anthracite" Spontaneous combustion tendency
Easy to spontaneously ignite
Not easy to spontaneously ignite
Oxygen absorption of coal, cm/g·dry coal
0. 41~0.70
Oxygen absorption of coal, cm/g·dry coal
The allowable parallel error of the measurement result of oxygen absorption of coal shall not exceed the provisions of Table 3: Table 3 Parallel experimental error of oxygen absorption measurement of coal Same laboratory
Different laboratories
A1 General
MT/T 707 - 1997
Appendix A
(Appendix to the standard)
Sampling method for identification of spontaneous combustion tendency of coal seams
This sampling method is applicable to the collection of coal samples by chromatographic oxygen absorption identification method. The following provisions should be followed when sampling:
A2 Before designing the mine, or deepening the level, or before mining a new area, representative original coal samples should be collected from all mining coal seams and stratified coal mining faces or excavation faces.
A3 When the sampling site meets one of the following conditions, coal samples should be collected separately, and the specific conditions of the sampling site should be described: A3.1 Complex geological structure, Areas with severe damage (such as damage zones caused by folds, faults, etc. and magma intrusions); A3.2 Locations where the distribution of coal rock components in the coal seam is obvious, such as the concentrated presence of mirror coal and bright coal, and the presence of charcoal; A3.3 Locations rich in pyrite in the coal seam. A4 When taking samples from grinding rock piles or sampling in open-pit mines, the sampling points should be arranged in accordance with relevant regulations, and representative coal samples should be taken. When the mining steps are high, samples should be taken in representative sections. A5 When sampling, first peel off the oxidized part of the coal seam surface, then clean the bottom plate in front of the sampling point, cover it with canvas or plastic sheeting, and then vertically along the working face. Draw two lines in the direction, with a width of 100~150mm between the two lines, and collect 50mm thick coal between the two lines as the initial coal sample.
A6 Break the initial coal sample into 20~30mm particles, mix them evenly, and reduce them to about 1kg according to the cone pile quartering method. Put them into iron sticks (or thicker plastic bags) as raw coal samples, seal them tightly, and send them to the laboratory or mail them. A7 When sampling a newly mined coal seam or layer for the first time to identify its spontaneous combustion tendency, it is necessary to collect 2~3 coal samples from different locations in the same coal seam or layer for identification.
A8 Take samples from drilling holes for geological exploration When taking coal core samples:
A8.1 Take out the coal core from the borehole, and immediately remove the stone, mud skin and the burnt part of the coal core. If necessary, wash the coal core with water, but do not soak it in water.
A8.2 Put the cleaned coal core into an iron stick (or thick plastic bag) immediately, seal it tightly and send it to the laboratory or mail it. A8.3 The coal core taken should also be representative, and the coal seam, thickness and inclination should be noted. A9 Each coal sample must have two labels, which should be placed in the container for the coal sample (be sure to wrap it in a plastic bag to prevent moisture) and affixed to the outside of the container. The labels should be filled in as required and the handwriting should be clear. A10 label:
a) coal sample number (sample number of the sending unit); b) bureau and mine name;
c) coal seam name;
d) coal type (according to national classification standards);
e) coal seam thickness;
f) coal seam inclination;
g) coal mining method;
h) spontaneous combustion period (empirical combustion period);
i) sampling location;
j) sampling date and sampling person.
MT/T 707—1997
Appendix B
Appendix to the standard)
Supplementary provisions for the preparation of coal samples for identification of spontaneous combustion tendency of coal seams After receiving the coal sample, the sample label shall be checked and the laboratory number shall be registered. B1
B2 When the moisture content of the coal sample to be inspected is high, it should be dried at room temperature and then all the coal samples should be crushed to less than 10mm for reduction. Take 100-150g as the coal sample for analysis, put it into a 250mm wide-mouth bottle, affix a label, and the remaining coal samples should be sealed in the original packaging. B3 Make sure that all 100-150g of coal samples for analysis are crushed to less than 0.15mm, and 0.10~~0.15mm should account for more than 70%.
The crushed coal sample (sealed and stored in a wide-mouth bottle) should complete all tests within 30 days and issue an identification report. B4
B5 The coal samples submitted for inspection and the coal samples for analysis should be stored for 6 months after the issuance of the analysis report. Appendix C
(Appendix to the standard)
Schematic diagram of the structure of the special standard sample tube15mm should account for more than 70%.
The crushed coal sample (sealed in a wide-mouth bottle) shall complete all tests within 30 days and issue an identification report. B4
B5 The coal samples submitted for inspection and the coal samples for analysis shall be stored for 6 months after the analysis report is issued. Appendix C
(Standard Appendix)
Structure diagram of special standard sample tube15mm should account for more than 70%.
The crushed coal sample (sealed in a wide-mouth bottle) shall complete all tests within 30 days and issue an identification report. B4
B5 The coal samples submitted for inspection and the coal samples for analysis shall be stored for 6 months after the analysis report is issued. Appendix C
(Standard Appendix)bZxz.net
Structure diagram of special standard sample tube
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