This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles

for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

Designation: D4239 − 18´1

Standard Test Method for

Sulfur in the Analysis Sample of Coal and Coke Using High-
Temperature Tube Furnace Combustion1
This standard is issued under the fixed designation D4239; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the U.S. Department of Defense.

ε1 NOTE—Table 1 was corrected editorially in October 2018.

1. Scope* D2013/D2013M Practice for Preparing Coal Samples for

1.1 This test method covers the determination of sulfur in Analysis
samples of coal or coke by high-temperature tube furnace D3173/D3173M Test Method for Moisture in the Analysis
combustion. Sample of Coal and Coke
1.1.1 Two analysis methods are described. D3176 Practice for Ultimate Analysis of Coal and Coke
D3180 Practice for Calculating Coal and Coke Analyses
1.2 When automated equipment is used, either method can from As-Determined to Different Bases
be classified as an instrumental method. D7448 Practice for Establishing the Competence of Labora-
1.3 The values stated in SI units are to be regarded as tories Using ASTM Procedures in the Sampling and

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standard. The values given in parentheses after SI units are
provided for information only and are not considered standard.
Analysis of Coal and Coke
D7582 Test Methods for Proximate Analysis of Coal and

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1.4 All percentages are percent mass fractions unless other- Coke by Macro Thermogravimetric Analysis
wise noted. E691 Practice for Conducting an Interlaboratory Study to
Determine the Precision of a Test Method
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1.5 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro-
2.2 ISO Standard:3
ISO 5725-6 Accuracy (trueness and precision) of measure-
ment methods and results—Part 6: Use in practice of
priate safety, health, and environmental practices and deter-
ASTM D4239-18e1 accuracy values
mine the applicability of regulatory limitations prior to use.
ISO 11722 Solid mineral fuels—Hard coal—Determination
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1.6 This international standard was developed in accor-
of moisture in the general analysis test sample by drying
dance with internationally recognized principles on standard-
in nitrogen
ization established in the Decision on Principles for the
Development of International Standards, Guides and Recom- 3. Summary of Test Method
mendations issued by the World Trade Organization Technical
Barriers to Trade (TBT) Committee. 3.1 Combustion Method A (1350 °C)—A weighed test por-
tion of sample is burned in a tube furnace at a minimum
2. Referenced Documents combustion tube operating temperature of 1350 °C in a stream
2 of oxygen. During combustion at temperatures above 1350 °C,
2.1 ASTM Standards:
the sulfur and sulfur compounds contained in the sample are
D346/D346M Practice for Collection and Preparation of
decomposed and oxidized almost exclusively to gaseous sulfur
Coke Samples for Laboratory Analysis
dioxide, SO2. Moisture and particulates are removed from the
gas by filters. The gas stream is passed through a cell in which
1
sulfur dioxide is measured by an infrared (IR) absorption
This test method is under the jurisdiction of ASTM Committee D05 on Coal
and Coke and is the direct responsibility of Subcommittee D05.21 on Methods of detector. Sulfur dioxide absorbs IR energy at a precise wave-
Analysis. length within the IR spectrum. Energy is absorbed as the gas
Current edition approved Sept. 1, 2018. Published October 2018. Originally passes through the cell body in which the IR energy is being
approved in 1983. Last previous edition approved in 2017 as D4239 – 17. DOI:
10.1520/D4239-18E01.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
3
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Available from International Organization for Standardization (ISO), 1, ch. de
Standards volume information, refer to the standard’s Document Summary page on la Voie-Creuse, Case postale 56, CH-1211, Geneva 20, Switzerland, http://
the ASTM website. www.iso.ch.

*A Summary of Changes section appears at the end of this standard

Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States

1
 D4239 − 18´1
transmitted: thus, at the detector, less energy is received. All 4.2 Results of the sulfur analysis are used for evaluation of
other IR energy is eliminated from reaching the detector by a coal preparation and cleaning, evaluation of potential sulfur
precise wavelength filter. Thus, the absorption of IR energy can emissions from coal and coke combustion or conversion
be attributed only to sulfur dioxide whose concentration is processes, and evaluation of coal and coke quality in relation to
proportional to the change in energy at the detector. One cell is contract specifications, as well as for scientific purposes.
used as both a reference and a measurement chamber. Total 4.3 The competency of laboratories with respect to use of
sulfur as sulfur dioxide is detected on a continuous basis. this standard can be established through reference to Practice
3.1.1 One procedure for Method A uses coal or coke D7448.
reference materials to calibrate the sulfur analyzer. A second
procedure for Method A uses a pure substance, BBOT, to 5. Sample
calibrate the sulfur analyzer. 5.1 Pulverize the sample to pass 250 µm (No. 60) sieve and
3.2 Combustion Method B (1150 °C)—A weighed test por- mix thoroughly in accordance with Practice D2013/D2013M or
tion of sample is burned in a quartz combustion tube in a Practice D346/D346M.
stream of oxygen with an equal or excess weight of tungsten 5.2 Analyze a separate portion of the analysis sample for
trioxide (WO3). Sulfur is oxidized during the reaction of the moisture content in accordance with Test Method D3173/
sample and WO3. The tube furnace is operated at a minimum D3173M, or Test Methods D7582 or ISO 11722 for calcula-
combustion tube operating temperature of 1150 °C and tin (Sn) tions to other than the as-determined basis.
sample boats are utilized. Moisture and particulates are re-
moved from the combustion gas by filters. The gas stream is 5.3 Procedures for calculating as-determined sulfur values
then passed through a cell in which sulfur dioxide is measured obtained from the analysis sample to other bases are described
by an infrared (IR) absorption detector. Sulfur dioxide absorbs in Practices D3176 and D3180.
IR energy at a precise wavelength within the IR spectrum. 6. Apparatus
Energy is absorbed as the gas passes through the cell body in
which the IR energy is being transmitted: thus, at the detector, Combustion Method A (1350 °C)
less energy is received. All other IR energy is eliminated from
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6.1 Measurement Apparatus—Equipped to combust the
reaching the detector by a precise wavelength filter. Thus, the
sample as described in 3.1 (see Fig. 1).
absorption of IR energy can be attributed only to sulfur dioxide
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6.2 Tube Furnace—Capable of heating the hot zone or outer
whose concentration is proportional to the change in energy at
surface of the combustion tube, or both (6.3) to at least
the detector. One cell is used as both a reference and a
1350 °C. It is normally heated electrically using resistance
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measurement chamber. Total sulfur as sulfur dioxide is de-
tected on a continuous basis. rods, a resistance wire, or molybdenum disilicide elements.
Specific dimensions can vary with manufacturer’s design.
4. Significance and Use 6.3 Combustion Tube—Made of mullite, porcelain, or zircon
ASTM
4.1 Sulfur is part of the ultimate analysis of coal D4239-18e1
and coke. with provisions for routing the gases produced by combustion
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FIG. 1 Apparatus for Determination of Sulfur by Infrared Detection, Method A

2
 D4239 − 18´1
through the infrared cell. The tube may have a boat stop made 7.2 Magnesium Perchlorate—(Warning—Magnesium per-
of reticulated ceramics heated to 1350 °C that serves to chlorate is a strong oxidizing agent. Do not regenerate the
complete the combustion of sulfur containing materials. absorbent. Do not allow contact with organic materials or
6.4 Sample Combustion Boats, made of iron-free material reducing agents.)
and of a convenient size suitable for the dimensions of the 7.3 Oxygen, 99.5 % Pure—Compressed gas contained in a
combustion tube. cylinder equipped with a suitable pressure regulator and a
6.5 Boat Puller—Where required, a rod of a heat-resistant needle valve to control gas flow. (Warning—Pure oxygen
material with a bent or disk end to insert and remove boats vigorously accelerates combustion. Verify all regulators, lines,
from the combustion tube. and valves are free of grease and oil.)
6.6 Balance—A stand-alone balance or a balance integrated 7.4 Reference Materials, Reference Material (RM)—that are
with the instrument, with a resolution of at least 0.3 % relative coal(s) or coke(s) prepared by a national metrology body.
of the test portion mass. Other materials that are coal(s) or coke(s) with documented
traceability to reference material (CRM) coal(s) or coke(s)
Combustion Method B (1150 °C) prepared by a national metrology body can also be used. Only
6.7 Measurement Apparatus—Equipped to combust the use material(s) with an assigned value and assigned uncertainty
sample as described in 3.2 (see Fig. 2). for sulfur. The uncertainty expressed as the confidence interval
of the assigned value shall be less than the reproducibility
6.8 Tube Furnace—Capable of heating the hot zone or outer standard deviation SR specified in the appropriate section on
surface of the combustion tube, or both (6.9) to at least Precision and Bias of this test method.
1150 °C. It is normally heated electrically using resistance 7.4.1 To minimize problems with instrument calibration or
wire. Specific dimensions can vary with manufacturer’s design. calibration verification mix all reference material before re-
6.9 Combustion Tube—Made of quartz with provisions for moving the test portion from the container. Do not use the
routing the gases produced by combustion through the infrared reference material for calibration or calibration verification
cell. when less than 2 g remain in the container. The remaining

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6.10 Sample Combustion Boat—Made of an iron-free tin
material and of a convenient size suitable for the dimensions of
material can be used for instrument conditioning.
7.5 BBOT (2,5-di(5-tert-butylbenzoxazol-2-yl)thiophene,
the combustion tube.
7. Reagents
(https://standards.iteh.ai) C H N O S)—A pure substance and certified reference ma-
26 26 2
terial for sulfur (7.47 % sulfur).
2

7.1 Purity of Reagents—Use reagent Document

grade chemicals in all Preview
tests. Unless otherwise indicated, it is intended that all reagents
7.6 Tungsten Oxide (WO )—A combustion promoter and a
3
fluxing agent. (Warning—Tungsten Oxide is a strong oxidiz-
ing agent.)
conform to the specifications of the Committee on Available
Reagents of the American Chemical Society, ASTM D4239-18e1
where such
8. Procedure
specifications are available.4 Other grades can be used, pro-
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8.1 Instrument Preparation—Perform apparatus set up sys-
vided it is first ascertained the reagent is of sufficiently high
purity to permit its use without lessening the accuracy of the tem checks in accordance with manufacturer’s instructions.
determination. 8.1.1 Balance Calibration—Calibrate the instrument bal-
ance in accordance with manufacturer’s instructions.
4
Reagent Chemicals, American Chemical Society Specifications , American 8.2 Calibration of the Infrared Detection System—If the
Chemical Society, Washington, DC. For suggestions on the testing of reagents not instrument has been previously calibrated in accordance with
listed by the American Chemical Society, see Analar Standards for Laboratory
the section on instrument calibration, proceed to the Analysis
Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia
and National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville, Procedure, otherwise carry out a calibration as specified in the
MD. following section.

FIG. 2 Apparatus for Determination of Sulfur by Infrared Detection, Method B

3
 D4239 − 18´1
8.2.1 Calibration with Coal and Coke Certified Reference (8.2.1). Use a mass that does not exceed the maximum mass
Materials—Select reference materials (7.4), in the range of the used for instrument calibration and with a sulfur value within
samples to be analyzed. Use at least three such reference the range of the instrument calibration.
materials, for each range of sulfur values to be tested. Select 8.2.3.1 Verify that the dry basis results for consecutive
one reference material containing at least as much sulfur as the determinations agree within the repeatability limit of this test
highest level of sulfur expected. Select two additional refer- method.
ence materials, one approximately at the mid-point of the range 8.2.3.2 Verify that each dry basis result agrees with the
and one below the lowest level of sulfur expected. assigned value within 0.707 multiplied by the reproducibility
8.2.1.1 Use a mass of material recommended by the appa- limit (0.707R) of this test method.
ratus manufacturer to carry out a minimum of three determi-
nations to condition the equipment before calibration. Use a NOTE 2—The acceptance limit is derived from the reproducibility limit
in accordance with Section 4.2.3 on “Comparison with a reference value
material with a sulfur value near the mid point of the expected for one laboratory” of ISO 5725-6.
calibration range.
8.2.3.3 If any of these acceptance criteria fails, reject all
8.2.1.2 For each reference coal or coke employed for
determinations back to the last acceptable reference material
calibration, use the as-determined sulfur value previously
determinations. Check instrument set-up (8.1) and condition
calculated from the certified dry-basis sulfur value and residual
the instrument (8.2.1.1). Calibrate the instrument according to
moisture determined using either Test Methods D3173/
8.2 before proceeding with determinations. Repeat all samples
D3173M, D7582, or ISO 11722. Use a mass of material and the
analyzed since the last successful calibration verification.
calibration procedure recommended by the apparatus manufac-
turer. Weigh in accordance with section 6.6 and evenly spread 8.3 Combustion Method A (1350 °C)—Set up the apparatus
the test portion of the reference material into the sample (see 8.1) and verify the calibration (see 8.2.3).
combustion boat (6.4). Position the sample in the hot zone of 8.3.1 Raise the furnace temperature as recommended by the
the furnace until the instrument returns to baseline as indicated manufacturer to at least 1350 °C. Weigh a mass of the sample
according to settings recommended by the manufacturer. If the in accordance with section 6.6 and not exceeding the maximum
analysis time exceeds the maximum analysis time recom-
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mass of reference material(s) used for calibration. Analyze the
mended by the manufacturer take corrective action as recom- test samples using the apparatus conditions employed for
mended by the manufacturer. calibration (8.2.1).
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8.2.2 Calibration with BBOT—To meet the precision re-
quirements of this method, six calibration points are required
8.3.2 When the analysis is complete, the instrument indi-
cates the sulfur value.

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for a linear fit and eight calibration points are required for a
8.4 Combustion Method B (1150 °C)—Set up the apparatus
nonlinear fit. A calibration point consists of a determination on
(see 8.1) and verify the calibration (see 8.2.3).
a single test portion of calibration material. Select test portions
of the calibrant that have at least as much sulfur as the highest 8.4.1 Raise the furnace temperature as recommended by the
ASTM D4239-18e1
level of sulfur expected, test portions of the calibrant that have manufacturer to at least 1150 °C.
8.4.2 Weigh to the nearest 1 mg and evenly spread into a
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as much sulfur as the lowest level of sulfur expected and test
combustion boat (6.10) a portion of tungsten oxide equal to the
portions spread evenly in between the highest and lowest levels
of sulfur. target weight, typically 100 mg, of the sample analysis aliquot.
8.2.2.1 The mass of the calibrant needed can be calculated 8.4.3 While evenly spreading the sample material into the
using the following equation: (Note 1). same combustion boat, weigh in accordance with section 6.6 a
sample aliquot equal (610 mg) to the weight of tungsten oxide.
~ M T 3 S AD!
MC 5 (1) 8.4.4 For high-rank (Bituminous and Coke) materials add
SC
additional tungsten oxide as required to ensure that its weight
where: is 10 mg (6 5 mg) in excess of the sample aliquot weight
MC = Mass of calibrant, measured.
MT = Mass normally used for test samples, 8.4.5 For low-rank (Sub-bituminous and lignite and high
SAD = Percent sulfur (as-determined) in the test sample, and ash) test samples or any material of unknown BTU/gross
SC = Percent sulfur in the pure substance calibrant. calorific value content, add additional tungsten oxide as re-
quired to ensure that its weight is at least double (610 mg) the
NOTE 1—In the interlaboratory study that yielded the data for the
precision statement for this method, the mass of BBOT used for sample aliquot weight measured.
calibration ranged from about 15 mg to over 80 mg. Some analyzers may 8.4.6 For test sample materials, do not exceed the maximum
use larger amounts. mass of reference material(s) used for calibration. Analyze the
8.2.3 Calibration Verification—Carry out a minimum of test samples using the apparatus conditions employed for
three determinations to condition the equipment before cali- calibration.
bration verification (see 8.2.1.1). Verify the instrument calibra- 8.4.7 Follow the manufacturer’s recommended combustion
tion prior to analyzing test samples, upon completion of all test sample boat handling procedures to position the sample into
samples and as needed to meet quality control requirements. the hot zone of the furnace and start the analysis.
Analyze a test portion of reference material(s) (7.4) using the 8.4.8 When the analysis is complete, the instrument indi-
apparatus conditions employed for instrument calibration cates the sulfur value.