ASTM D5263-23

Standard Test Method for Determining the Relative Degree of Oxidation in Bituminous Coal by Alkali Extraction

SIGNIFICANCE AND USE
5.1 This test method is a relative measure of the degree of oxidation present in coal. It does not determine the quantitative amount of oxidized coal present. It is only intended to serve as a guide to the supplier, buyer, and user for selecting coals for metallurgical use.
Note 1: Lower rank bituminous coals are more easily extracted than higher rank coal.
SCOPE
1.1 This colorimetric test method describes the determination of the relative degree of oxidation by alkali extraction of coals that are high volatile A bituminous to low volatile bituminous in rank.  
1.2 This test cannot be sensitive to thermally oxidized coal. It is intended for coals that may be oxidized as a result of weathering.  
1.3 Units—The values stated in SI units are to be regarded as standard. The values given in parentheses after SI units are provided for information only and are not considered standard.  
1.4 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 appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.5 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.

General Information

• Status: Published
• Publication Date: 28-Feb-2023
• ICS: 73.040 - Coals
• Technical Committee: D05 - Coal and Coke
• Drafting Committee: D05.15 - Metallurgical Properties of Coal and Coke

Relations

• Refers: ASTM D7448-16 - Standard Practice for Establishing the Competence of Laboratories Using ASTM Procedures in the Sampling and Analysis of Coal and Coke (Withdrawn 2024)
• Effective Date: 01-Mar-2016
• Refers: ASTM D7448-09 - Standard Practice for Establishing the Competence of Laboratories Using ASTM Procedures in the Sampling and Analysis of Coal and Coke
• Effective Date: 01-Nov-2009
• Refers: ASTM D1193-06 - Standard Specification for Reagent Water
• Effective Date: 01-Mar-2006
• Refers: ASTM D1193-99e1 - Standard Specification for Reagent Water
• Effective Date: 10-Feb-1999
• Refers: ASTM D1193-99 - Standard Specification for Reagent Water
• Effective Date: 10-Feb-1999

Overview

ASTM D5263-23 is the internationally recognized "Standard Test Method for Determining the Relative Degree of Oxidation in Bituminous Coal by Alkali Extraction." Developed by ASTM, this colorimetric test method is designed to assess the relative degree of oxidation in bituminous coal samples. It uses alkali extraction to identify weathering-related oxidation, providing crucial information for suppliers, buyers, and users of coal, particularly for metallurgical applications where coal quality can directly impact processes such as coke production.

This test does not measure the quantitative amount of oxidized coal but offers a comparative indication to guide coal selection, helping stakeholders minimize risks associated with oxidized material.

Key Topics

• Relative Degree of Oxidation: The method determines how much a coal sample has been oxidized due to weathering - a common concern in storage and transportation. This is especially important for high volatile A to low volatile bituminous coals.
• Alkali Extraction & Colorimetric Analysis: By extracting humic acids with sodium hydroxide solution, the sample’s degree of oxidation is measured through spectrophotometric transmittance at 520 nm. The intensity correlates with oxidation level.
• Test Sensitivity: The method is not sensitive to coal oxidized by heat (thermal oxidation) but is especially effective for identifying oxidation caused by environmental exposure (weathering).
• Practical Guidelines: Percent transmittance at 520 nm is used to interpret results:
  • Greater than 90%: Coal is not oxidized, suitable for metallurgical use.
  • 80%-90%: Coal may be partially oxidized, and close monitoring is advised.
  • Less than 80%: Coal is oxidized and may cause issues in coke quality and plant operations.
• Instrumentation and Materials: The standard specifies the use of a transmission spectrophotometer, standard glassware, filter papers, analytical balances, and sodium hydroxide solution, ensuring consistent and reliable results across laboratories.

Applications

• Coal Quality Assessment: Essential for evaluating coal intended for metallurgical purposes such as coking, where oxidation can significantly affect coke strength and yield.
• Supplier and Buyer Guidance: Provides a standardized method for stakeholders to make informed decisions about the suitability of coal lots before use or shipment.
• Stockpile and Weathering Management: Enables coal consigners and power plant operators to monitor the degree of oxidation that occurs during storage, aiding in inventory management and risk mitigation.
• Laboratory Proficiency and Quality Control: Supports internal and external quality assurance programs by delivering repeatable and reproducible results, vital for contract compliance and dispute resolution.

Related Standards

• ASTM D1193: Specification for Reagent Water - defines water quality for laboratory procedures.
• ASTM D7448: Practice for Establishing the Competence of Laboratories Using ASTM Procedures in the Sampling and Analysis of Coal and Coke - covers laboratory quality assurance for coal analysis.
• Other ASTM Coal and Coke Standards: Related test methods address topics such as coal sampling, proximate/ultimate analysis, and coking properties.

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Keywords: ASTM D5263, bituminous coal oxidation, alkali extraction, colorimetric test, metallurgical coal selection, coal weathering, coal quality testing, spectrophotometric analysis, coke production, coal supplier guidelines

By applying ASTM D5263-23, coal industry professionals benefit from standardized, reliable results to inform procurement, processing, and quality assurance decisions, ensuring optimal performance in metallurgical applications.

Standards Content (Sample)

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: D5263 − 23
Standard Test Method for
Determining the Relative Degree of Oxidation in Bituminous
Coal by Alkali Extraction
This standard is issued under the fixed designation D5263; 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.
1. Scope 4. Summary of Test Method
1.1 This colorimetric test method describes the determina- 4.1 Humic acids, which are present in oxidized coals, are
tion of the relative degree of oxidation by alkali extraction of extracted from the coal with sodium hydroxide solution. The
coals that are high volatile A bituminous to low volatile degree of oxidation is determined by colorimetrically measur-
bituminous in rank. ing the transmittance of the alkali extract solution at 520 nm.
The intensity of the color produced by the humic acids is a
1.2 This test cannot be sensitive to thermally oxidized coal.
function of the degree of oxidation.
It is intended for coals that may be oxidized as a result of
weathering.
5. Significance and Use
1.3 Units—The values stated in SI units are to be regarded
5.1 This test method is a relative measure of the degree of
as standard. The values given in parentheses after SI units are
oxidation present in coal. It does not determine the quantitative
provided for information only and are not considered standard.
amount of oxidized coal present. It is only intended to serve as
1.4 This standard does not purport to address all of the
a guide to the supplier, buyer, and user for selecting coals for
safety concerns, if any, associated with its use. It is the
metallurgical use.
responsibility of the user of this standard to establish appro-
NOTE 1—Lower rank bituminous coals are more easily extracted than
priate safety, health, and environmental practices and deter-
higher rank coal.
mine the applicability of regulatory limitations prior to use.
1.5 This international standard was developed in accor-
6. Apparatus
dance with internationally recognized principles on standard-
6.1 Transmission Spectrophotometer—Single-beam, grating
ization established in the Decision on Principles for the
spectrophotometer having a wavelength range of 340 nm to
Development of International Standards, Guides and Recom-
900 nm.
mendations issued by the World Trade Organization Technical
6.2 Glass Test Tubes/Cuvettes, with light paths ranging from
Barriers to Trade (TBT) Committee.
10 mm to 17 mm may be used. Test tubes with an inside
2. Referenced Documents
diameter of 17 mm 6 0.3 mm are commonly used.
2.1 ASTM Standards:
6.3 Analytical Balance, sensitive to 0.001 g.
D1193 Specification for Reagent Water
6.4 Hot Plate, capable of bringing aqueous solutions to a
D7448 Practice for Establishing the Competence of Labora-
boil.
tories Using ASTM Procedures in the Sampling and
Analysis of Coal and Coke
6.5 Thermometer, capable of measuring up to 100 °C with a
sensitivity of 6 0.5 °C.
3. Terminology
6.6 Filter Papers, Type II, Class F and G.
3.1 There are no terms in this standard that require new or
6.7 Timer, capable of measuring 30 min to the nearest
other than dictionary definitions.
second.
This test method is under the jurisdiction of ASTM Committee D05 on Coal
6.8 Graduated Cylinder, 100 mL capacity.
and Coke and is the direct responsibility of Subcommittee D05.15 on Metallurgical
Properties of Coal and Coke.
6.9 Beakers, 400 mL capacity.
Current edition approved March 1, 2023. Published May 2023. Originally
approved in 1992. Last previous edition approved in 2021 as D5263 – 21. DOI:
7. Reagents
10.1520/D5263-23.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or 7.1 Sodium Hydroxide Solution (certified 1N).
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
7.2 Octylphenoxypolyethoxyethanol Nonionic Surfactant—
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. Wetting agent.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D5263 − 23
TABLE 1 Guidelines for General Acceptance/Rejection Levels of
9.8 Transfer the entire blank solution or test solution to a
Oxidized Coal
stack of one Type II Class F filter paper on top of one Type II
Percent Transmittance at
Glass G filter paper. The beaker shall not be rinsed onto the
Interpretation of Results
520 nm, 17 mm Light Path
filter paper. It is not significant if some coal remains in the
> 90 Coal is not oxidized. Suitable for metallurgical
beaker. Filter, by gravity, the slurry into a 100 mL graduated
usage.
80 to 90 Coal may be oxidized. If it is being used cylinder, making sure funnel and graduated cylinder are dry
metallurgically, it should be monitored
before each test. After filtration, add deionized (distilled) water
closely for further changes in oxidation.
(Type II, Specification D1193) to the cylinder to bring the
< 80 Coal is oxidized. Coal at this level may cause
coke quality and coke plant operating solution to 80 mL and stir with a glass rod.
problems.
9.9 Adjust the 0 % and 100 % transmittance levels of the
spectrophotometer.
9.9.1 Adjust the spectrophotometer to read 0 % transmit-
7.2.1 Wetting agent shall not be diluted (100 % concentra-
tance by closing the lid of the sample/tube holder assembly of
tion).
the instrument.
9.9.2 Fill cuvette/test tube with the blank solution and insert
8. Calibration and Standardization
into the spectrophotometer.
8.1 Optical light filters with known absorbance/transmission
9.9.3 Adjust the spectrophotometer to read 100 % transmit-
shall be used to check wavelength accuracy and linearity of the
tance by inserting the blank solution (see 8.2).
spectrophotometer. Solutions with accurate absorbance values
9.9.4 Periodically during the analysis, check the span (0 %
can be found in published literature.
and 100 % transmittance) to be sure that the instrument has not
8.2 A b
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: D5263 − 21 D5263 − 23
Standard Test Method for
Determining the Relative Degree of Oxidation in Bituminous
Coal by Alkali Extraction
This standard is issued under the fixed designation D5263; 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.
1. Scope
1.1 This colorimetric test method describes the determination of the relative degree of oxidation by alkali extraction of coals that
are high volatile A bituminous to low volatile bituminous in rank.
1.2 This test cannot be sensitive to thermally oxidized coal. It is intended for coals that may be oxidized as a result of weathering.
1.3 Units—The values stated in SI units are to be regarded as standard. The values given in parentheses after SI units are provided
for information only and are not considered standard.
1.4 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 appropriate safety, health, and environmental practices and determine the applicability of
regulatory limitations prior to use.
1.5 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.
2. Referenced Documents
2.1 ASTM Standards:
D1193 Specification for Reagent Water
D7448 Practice for Establishing the Competence of Laboratories Using ASTM Procedures in the Sampling and Analysis of Coal
and Coke
3. Terminology
3.1 There are no terms in this standard that require new or other than dictionary definitions.
4. Summary of Test Method
4.1 Humic acids, which are present in oxidized coals, are extracted from the coal with sodium hydroxide solution. The degree of
This test method is under the jurisdiction of ASTM Committee D05 on Coal and Coke and is the direct responsibility of Subcommittee D05.15 on Metallurgical Properties
of Coal and Coke.
Current edition approved Dec. 1, 2021March 1, 2023. Published January 2022May 2023. Originally approved in 1992. Last previous edition approved in 20152021 as
D5263 – 15.D5263 – 21. DOI: 10.1520/D5263-21. 10.1520/D5263-23.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D5263 − 23
oxidation is determined by colorimetrically measuring the transmittance of the alkali extract solution at 520 nm. The intensity of
the color produced by the humic acids is a function of the degree of oxidation.
5. Significance and Use
5.1 This test method is a relative measure of the degree of oxidation present in coal. It does not determine the quantitative amount
of oxidized coal present. It is only intended to serve as a guide to the supplier, buyer, and user for selecting coals for metallurgical
use.
NOTE 1—Lower rank bituminous coals are more easily extracted than higher rank coal.
TABLE 1 Guidelines for General Acceptance/Rejection Levels of
Oxidized Coal
Percent Transmittance at
Interpretation of Results
520 nm, 17 mm Light Path
> 90 Coal is not oxidized. Suitable for metallurgical
usage.
80 to 90 Coal may be oxidized. If it is being used
metallurgically, it should be monitored
closely for further changes in oxidation.
< 80 Coal is oxidized. Coal at this level may cause
coke quality and coke plant operating
problems.
6. Apparatus
6.1 Transmission Spectrophotometer—Single-beam, grating spectrophotometer having a wavelength range of 340 nm to 900 nm.
6.2 Glass Test Tubes/Cuvettes, with light paths ranging from 10 mm to 17 mm may be used. Test tubes with an inside diameter
of 17 mm 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 a boil.
6.5 Thermometer, capable of measuring up to 100 °C with a sensitivity of 6 0.5 °C.
6.6 Filter Papers, Type II, Class F and G.
6.7 Timer, capable of measuring 30 min to the nearest second.
6.8 Graduated Cylinder, 100 mL capacity.
6.9 Beakers, 400 mL capacity.
7. Reagents
7.1 Sodium Hydroxide Solution (certified 1N).
7.2 Octylphenoxypolyethoxyethanol Nonionic Surfactant—Wetting agent.
7.2.1 Wetting agent shall not be diluted (100 % concentration).
D5263 − 23
8. Calibration and Standardization
8.1 Optical light filters with known absorbance/transmission shall be used to check wavelength accuracy and linearity of the
spectrophotometer. Solutions with accurate absorbance values can be found in published literature.
8.2 A blank solution consisting of 100 mL of 1N sodium hydroxide is prepared by following the procedure outlined in Section
9, except coal is not used.
9. Procedure
9.1 Activate the spectrophotometer and set at 520 nm wavelength; allow sufficient time for the instrument to stabilize (30 min).
9.2 Determine the mass of 1 g 6 0.01g of the minus 250 μm (No. 60 U.S. Standard Sieve Series) coal sample and transfer to a
standard 400 mL 400 mL beaker or optionally determine the mass directly into a previously tared beaker.
9.3 Add 100 mL of NaOH solution and one drop of wetting agent (100 % concentration) to the coal. Place a glass stirring rod into
the beaker.
NOTE 2—Wetting agent drop size can significantly influence results, with larger drop size causing lower transmittances.
9.4 Place beaker(s) onto a preheated hot plate and place a thermometer in the beaker.
9.5 Bring temperature of the contents to 98 °C. It shall take 3 min to 4 min to reach a boil, depending on the number of beakers
on the hot plate. When measuri
...