1、Designation: D 5263 93 (Reapproved 2001)Standard Test Method forDetermining the Relative Degree of Oxidation in BituminousCoal by Alkali Extraction1This standard is issued under the fixed designation D 5263; the number immediately following the designation indicates the year oforiginal adoption or,
2、in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This colorimetric method describes the determination ofthe relative degree of ox
3、idation by alkali extraction of coalsthat are high volatile A bituminous to low volatile bituminousin rank.1.2 This test cannot be sensitive to thermally oxidized coal.It is intended for coals that may be oxidized as a result ofweathering.1.3 This standard does not purport to address all of thesafet
4、y concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.1.4 The values stated in SI units shall be regarded asstandard.2. Referenced
5、 Documents2.1 ASTM Standards:D 1193 Specification for Reagent Water2D 4621 Guide for Quality Management in an Organizationthat Samples or Tests Coal and Coke33. Terminology3.1 There are no terms in this standard that require new orother than dictionary definitions.4. Summary of Test Method4.1 Humic
6、acids, which are present in oxidized coals, areextracted from the coal with sodium hydroxide solution. Thedegree of oxidation is determined by colorimetrically measur-ing the transmittance of the alkali extract solution at 520 nm.The intensity of the color produced by the humic acids is afunction of
7、 the degree of oxidation.5. Significance and Use5.1 This test method is a relative measure of the degree ofoxidation present in coal. It does not determine the quantitativeamount of oxidized coal present. It is only intended to serve asa guide to the supplier, buyer, and user for selecting coals for
8、metallurgical use.NOTE 1The values shown in Table 1 are based on the transmittanceobtained using the original procedure4(wavelength at 520 nm, 17-mmlight path, 2 to 3-min boiling time, dilution of the extract to 80 mL). Atthese conditions, coals that had transmittance values greater than 90 %were co
9、nsidered to be unoxidized, coals less than 80 % were consideredto be oxidized, and coals between 80 and 90 % were considered suspect.As this procedure becomes accepted as the standard and more experimen-tal data are gathered, modifications to these cutoff values are expected.Note that lower rank bit
10、uminous coals are more easily extracted thanhigher rank coal.6. Apparatus6.1 Transmission SpectrophotometerSingle-beam, gratingspectrophotometer having a wavelength range of 340 to 900nm.6.2 Glass Test Tubes/Cuvettes, with light paths ranging from10 to 17 mm may be used. Test tubes with an inside di
11、ameterof 17 6 0.3 mm are commonly used.6.3 Analytical Balance, sensitive to 0.001 g.6.4 Hot Plate, capable of bringing aqueous solutions to aboil.6.5 Thermometer, capable of measuring up to 100C with asensitivity of 60.5C.6.6 Filter Papers, Type II, Class F and G.56.7 Timer, capable of measuring 30
12、min to the nearestsecond.6.8 Graduated Cylinder, 100-mL capacity.6.9 Beakers, 400-mL capacity.1This test method is under the jurisdiction of ASTM Committee D05 on Coaland Coke and is the direct responsibility of Subcommittee D05.15 on MetalurgicalProperties of Coal and Coke.Current edition approved
13、Aug. 15, 1993. Published October 1993. Originallypublished as D 5263 92. Last previous edition D 5263 92.2Annual Book of ASTM Standards, Vol 11.01.3Annual Book of ASTM Standards, Vol 05.06.4Lowenhaupt, D. E., and Gray, R. J., International Journal of Coal Geology,1980, Vol 1, pp. 6373.5Whatman Grade
14、 Nos. 40 and 42 filter papers, or equivalent, have been foundsuitable for this purpose.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.7. Reagents7.1 Sodium Hydroxide Solution (certified 1N).7.2 Octylphenoxypolyethoxyethanol Nonionic
15、 SurfactantWetting agent.67.2.1 Wetting agent shall not be diluted (100 % concentra-tion).8. Calibration and Standardization8.1 Optical light filters with known absorbance/transmissionshall be used to check wavelength accuracy and linearity of thespectrophotometer. Solutions with accurate absorbance
16、 valuescan be found in published literature.78.2 A blank solution consisting of 100 mL of 1N sodiumhydroxide is prepared by following the procedure outlined inSection 9, except coal is not used.9. Procedure9.1 Activate the spectrophotometer and set at 520-nm wave-length; allow sufficient time for th
17、e instrument to stabilize (30min).9.2 Weigh out1g(60.01 g) of the 250-m (No. 60 U.S.Standard Sieve Series) coal sample.9.3 Transfer the coal to a standard 400-mL beaker.9.4 Add 100 mL of NaOH solution and one drop of wettingagent (100 % concentration) to the coal. Place a glass stirringrod into the
18、beaker.9.5 Place beaker(s) onto a preheated hot plate and place athermometer in the beaker.9.6 Bring temperature of the contents to 98C (208F). Itshall take 3 to 4 min to reach a boil, depending on the numberof beakers on the hot plate. When measuring the temperature ofthe blank solution or test sol
19、ution, or both, suspend thethermometer in a manner such that the temperature of thesolution and not the temperature of the beaker resting on top ofthe hot plate is being measured.9.7 At the time the blank solution or test solution, or both,in the beakers reaches the temperature of 98C (208F), set th
20、etimer for 3 min. Allow the solution to boil for 3 min, stirringthe contents for at least 5 s for each 1-min interval.9.8 After the 3-min boil, carefully remove hot beakers andallow to cool under ambient conditions for 30 min. This is alsodetermined by using a timer.9.9 Filter (by gravity) the entir
21、e blank solution or testsolution, or both, on a stack of one Type II Class F filter paperon top of one Type II Glass G filter paper. Filter the slurry intoa 100-mL graduated cylinder, making sure funnel and gradu-ated cylinder are dry before each test. After filtration, adddeionized (distilled) wate
22、r (Type II, Specification D 1193) tothe cylinder to bring the solution to 80 mL and stir with a glassrod.NOTE 2The beaker should not be rinsed onto the filter paper. It is notsignificant if some coal remains in the beaker.9.10 Adjust the 0 and 100 % transmittance levels of thespectrophotometer.9.10.
23、1 Adjust the spectrophotometer to read zero by closingthe lid of the sample/tube holder assembly of the instrument.9.10.2 Fill cuvette/test tube with the blank solution andinsert into the spectrophotometer.9.10.3 Adjust the spectrophotometer to read 100 % trans-mittance by inserting the blank soluti
24、on (see 8.2).9.11 Place the cuvette/test tube containing the test solutioninto the spectrophotometer; measure and record the percenttransmittance of each test solution.NOTE 3Use only cuvette/test tubes for the test solution that yield thesame transmittance values as the cuvettes/test tubes used with
25、 the blanksolutions.NOTE 4Periodically during the analysis, check the span (0 and 100 %transmittance) to be sure that the instrument has not drifted.10. Calculation10.1 Since the light path is a variable in this test, resultsmust be adjusted to a common basis to make comparisons. A17-mm light path w
26、ill be used. Thus, if the test was performedusing any other light path than 17 mm, the result must beadjusted to the 17-mm light path using Beers law.10.2 Adjust results as follows:Ax5 LogSTx100D(1)A175 Ax17 mm/bx! (2)T175 102A17! 3 100 (3)where:Tx= transmittance obtained by analysis, %;Ax= absorban
27、ce corresponding to Tx;bx= test light path, mm;A17= absorbance at 17-mm light path; andT17= transmittance (calculated) at 17-mm light path.11. Report11.1 Report the value T17(obtained in Section 9).11.2 All accountability and quality control aspects of GuideD 4621 apply to this test method.12. Preci
28、sion and Bias12.1 PrecisionThe relative precision of this test methodfor the determination of the degree of oxidation of bituminouscoal covers the range (percent transmittance) from 55 to 98 %.12.1.1 RepeatabilityThe difference in absolute values be-tween two consecutive tests conducted on the same
29、sample inthe same laboratory by the same operator using the same6Triton X-100, or equivalent wetting agent, has been found suitable for thispurpose.7Mellon, M. G., Analytical Absorption Spectroscopy, John Wiley alkali extraction; colorimetric; humic ac-ids; oxidation (weathering); transmittanceASTM
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