ASTM D6559-00A(2016)e1

Standard Test Method for Determination of Thermogravimetric (TGA) Air Reactivity of Baked Carbon Anodes and Cathode Blocks

SIGNIFICANCE AND USE
5.1 The air reactivity rates are used to quantify the tendency of a carbon artifact to react with air. Carbon consumed by this unwanted side reaction is unavailable for the primary reactions of reducing alumina to the primary metal. Air reactivity dusting rate is used by some companies to quantify the tendency of the coke aggregate or binder coke of a carbon artifact to selectively react with these gases. Preferential attack of the binder coke or coke aggregate of a carbon artifact by these gases causes some carbon to fall off or dust, making the carbon unavailable for the primary reaction of reducing alumina and, more importantly, reducing the efficiency of the aluminum reduction cell.  
5.2 Comparison of air reactivity and dusting rates is useful in selecting raw materials for the manufacture of commercial anodes for specific smelting technologies in the aluminum reduction industry.  
5.3 Air reactivity rates are used for evaluating effectiveness and beneficiation processes or for research purposes.
SCOPE
1.1 This test method covers the thermogravimetric (TGA) determination of air reactivity and dusting of shaped carbon anodes and cathode blocks used in the aluminum reduction industry. The apparatus selection covers a significant variety of types with various thermal conditions, sample size capability, materials of construction, and procedures for determining the mass loss and subsequent rate of reaction. This test method standardizes the variables of sample dimensions, reaction temperature, gas velocity over the exposed surfaces, and reaction time such that results obtained on different apparatuses are correlatable.  
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.3 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 and health practices and determine the applicability of regulatory limitations prior to use.

General Information

• Status: Historical
• Publication Date: 31-Mar-2016
• ICS: 77.020 - Production of metals
• Technical Committee: D02 - Petroleum Products, Liquid Fuels, and Lubricants
• Drafting Committee: D02.05 - Properties of Fuels, Petroleum Coke and Carbon Material

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
´1
Designation: D6559 − 00a (Reapproved 2016)
Standard Test Method for
Determination of Thermogravimetric (TGA) Air Reactivity of
Baked Carbon Anodes and Cathode Blocks
This standard is issued under the fixed designation D6559; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
ε NOTE—SI units formatting was corrected editorially in May 2016.
1. Scope 3. Terminology
3.1 Definitions of Terms Specific to This Standard:
1.1 This test method covers the thermogravimetric (TGA)
3.1.1 dusting, n—the quantity of carbon that falls off the
determination of air reactivity and dusting of shaped carbon
carbonartifactwhileinthereactionchamberandiscollectedin
anodes and cathode blocks used in the aluminum reduction
the container at the bottom of the reaction chamber.
industry.Theapparatusselectioncoversasignificantvarietyof
types with various thermal conditions, sample size capability,
3.1.2 final air reactivity, n—the mass loss of the carbon
materials of construction, and procedures for determining the
artifactduringthefinal30minofexposuretoairinthereaction
mass loss and subsequent rate of reaction. This test method
chamber divided by the initial geometric (right cylindrical)
standardizes the variables of sample dimensions, reaction
exposed surface area of the sample, expressed as milligrams
temperature, gas velocity over the exposed surfaces, and
per centimetre squared per hour.
reactiontimesuchthatresultsobtainedondifferentapparatuses
3.1.3 initial air reactivity, n—the mass loss of the carbon
are correlatable.
artifactduringthefirst30minofexposuretoairinthereaction
1.2 The values stated in SI units are to be regarded as chamber divided by the initial geometric (right cylindrical)
exposed surface area of the sample, expressed as milligrams
standard. No other units of measurement are included in this
standard. per centimetre squared per hour.
3.1.4 total air reactivity, n—thetotalmasslossofthecarbon
1.3 This standard does not purport to address all of the
artifact(includingdusting)duringthetotaltimethatthesample
safety concerns, if any, associated with its use. It is the
is exposed to air (180min) in the reaction chamber divided by
responsibility of the user of this standard to establish appro-
the initial geometric (right cylindrical) exposed surface area of
priate safety and health practices and determine the applica-
thesample,expressedasmilligramspercentimetresquaredper
bility of regulatory limitations prior to use.
hour.
2. Referenced Documents
4. Summary of Test Method
2.1 ASTM Standards:
4.1 Initial, final, and total air reactivity and dusting are
D6353Guide for Sampling Plan and Core Sampling for
determined by passing air at flow rates, giving a standard
Prebaked Anodes Used in Aluminum Production
velocity of reactant gas around cylindrically shaped carbon
D6354Guide for Sampling Plan and Core Sampling of
artifacts under nearly isothermal conditions for a specified
Carbon Cathode Blocks Used in Aluminum Production
length of time. The reactivity is determined by continuously
E691Practice for Conducting an Interlaboratory Study to
monitoring the sample mass loss. The dusting term is deter-
Determine the Precision of a Test Method
mined by collecting and determining the mass of carbon
particles that fall off the sample during reaction.
5. Significance and Use
This test method is under the jurisdiction of ASTM Committee D02 on
Petroleum Products, Liquid Fuels, and Lubricantsand is the direct responsibility of
5.1 Theairreactivityratesareusedtoquantifythetendency
SubcommitteeD02.05onPropertiesofFuels,PetroleumCokeandCarbonMaterial.
of a carbon artifact to react with air. Carbon consumed by this
Current edition approved April 1, 2016. Published May 2016. Originally
unwanted side reaction is unavailable for the primary reactions
approved in 2000. Last previous edition approved in 2010 as D6559–00a (2010).
DOI: 10.1520/D6559-00AR16E01.
ofreducingaluminatotheprimarymetal.Airreactivitydusting
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
rate is used by some companies to quantify the tendency of the
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
cokeaggregateorbindercokeofacarbonartifacttoselectively
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. react with these gases. Preferential attack of the binder coke or
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
´1
D6559 − 00a (2016)
coke aggregate of a carbon artifact by these gases causes some controller to adjust to the exothermic reaction that occurs
carbontofalloffor dust,makingthecarbonunavailableforthe duringtheairreactivitytest.Thecontrolthermocoupleshallbe
primary reaction of reducing alumina and, more importantly,
positioned 4mm 6 1mm from the side sample surface and
reducing the efficiency of the aluminum reduction cell.
centeredverticallywithin5mmofthecenter.Thefurnaceshall
be large enough to accept the reaction chamber.
5.2 Comparison of air reactivity and dusting rates is useful
in selecting raw materials for the manufacture of commercial
6.1.2 Reaction Chamber, consisting of a vertical tube con-
anodes for specific smelting technologies in the aluminum
structed of a material capable of withstanding the temperature
reduction industry.
ofthereactionwithsufficientinsidediameter(ID)toacceptthe
sample and sample holder while not affecting the gas flow to
5.3 Air reactivity rates are used for evaluating effectiveness
and from the sample (100mm 6 25mm ID is recommended).
and beneficiation processes or for research purposes.
The reaction chamber is to be constructed with a dust collec-
6. Apparatus
tion cup at the bottom, which is removable and capable of
capturing all the dust that falls off the sample during the test.
6.1 Theapparatustobeusedshouldbeassimpleaspossible
andbecommensuratewithwhatistobeachieved,theprincipal The most common materials of construction are quartz and
criteria being that the reaction rate is to be determined under Inconel.
isothermal conditions and unaffected by physical and chemical
6.1.3 Sample Holders, capable of supporting the sample in
properties inherent to the apparatus (such as gas diffusion
the reaction chamber for the duration of the test and should be
patterns, gas temperature, exposed sample surface area, and so
capable of being reusable. The sample holder shall not change
forth).Atypical apparatus that has been found to be suitable is
in mass during the test, affect the diffusion pattern of the gases
illustrated in Fig. 1.
to or from the sample, limit the gas accessible surface area of
6.1.1 Furnace and Controller, capable of maintaining con-
the test sample, or interfere with the free fall of dust from the
stant temperature within 62°C in the 100mm region centered
sample. A typical sample holder is illustrated in Fig. 2.
on the specimen. The example apparatus of Fig. 1 employs a
6.1.4 Gas Preheat Tube,extendingintothefirstheatzoneof
three zone heating element and associated controls to accom-
the reaction chamber to preheat the gases prior to entering the
plish this, but other methods such as tapered windings or long
reactionchamber.Thelengthanddiameterofthetubecanvary
linear heaters are also suitable. The control thermocouple is a
groundedtypeandshallbelocatedwithinthereactionchamber as long as the gases exiting the tube are the same temperature
near the surface of the test sample to allow the furnace as the reaction chamber. The inlet gas shall exit the preheat
FIG. 1 Typical Air Reactivity Apparatus
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D6559 − 00a (2016)
7. Reagents
7.1 Purity of Reagents—Reagent grade conforming to the
specifications of the Committee onAnalytical Reagents of the
American Chemical Society.
7.1.1 Nitrogen—99.95%.
7.1.2 Air—less than 0.1% moisture.
8. Sampling
8.1 Shape the carbon specimen by coring and cutting or
machiningtoarightcylindricalgeometry,50mm 61.0mmin
lengthand50mm 61.0mmindiameter.Mostsampleholders
require a hole of about 3mm diameter to be drilled vertically
through the center of the cylinder to accommodate a hanger.
Theshapedspecimenistobesmoothandfreeofvisiblecracks
and gouges. Sampling plans for anodes and cathode blocks
given in Guides D6353 and D6354 may be used if desired.
8.2 Dry the shaped specimen in an oven at 105°C 65°C
to constant weight.
8.3 The sample shall be made free of loose carbon dust and
impurities from the shaping process by blowing with dry air.
9. Calibration
FIG. 2 Typical Sample Holder
9.1 The purpose of this procedure is to establish a relation-
shipbetweenthecontrollersettingsforthreezonefurnacesand
the actual temperatures inside the reaction chamber in the
regionofthespecimen.Thelengthtobecalibratedisa100mm
tube downward to prevent channeling of the gas through the
(4in.) zone.
reaction chamber and to prevent plugging of the preheat tube
NOTE1—Forsinglezonefurnaces,thecalibrationprobeshallbeplaced
with carbon dust.
in center of where sample will be placed and confirm that the 100mm
6.1.5 Balance, capable of measuring the weight of the
zone is within 62°C.
sample and sample holder (approximately 200g maximum)
9.1.1 Insert a multiprobe thermocouple (for example, three
continuously throughout the duration of the test to the nearest
couples in same sheath with probes located at the tip and at
0.01g.
50mm and 100mm (2in. and 4in.) above the tip, or
...

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.
´1
Designation: D6559 − 00a (Reapproved 2010) D6559 − 00a (Reapproved 2016)
Standard Test Method for
Determination of Thermogravimetric (TGA) Air Reactivity of
Baked Carbon Anodes and Cathode Blocks
This standard is issued under the fixed designation D6559; 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.
ε NOTE—SI units formatting was corrected editorially in May 2016.
1. Scope
1.1 This test method covers the thermogravimetric (TGA) determination of air reactivity and dusting of shaped carbon anodes
and cathode blocks used in the aluminum reduction industry. The apparatus selection covers a significant variety of types with
various thermal conditions, sample size capability, materials of construction, and procedures for determining the mass loss and
subsequent rate of reaction. This test method standardizes the variables of sample dimensions, reaction temperature, gas velocity
over the exposed surfaces, and reaction time such that results obtained on different apparatuses are correlatable.
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.3 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 and health practices and determine the applicability of regulatory
limitations prior to use.
2. Referenced Documents
2.1 ASTM Standards:
D6353 Guide for Sampling Plan and Core Sampling for Prebaked Anodes Used in Aluminum Production
D6354 Guide for Sampling Plan and Core Sampling of Carbon Cathode Blocks Used in Aluminum Production
E691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
3. Terminology
3.1 Definitions of Terms Specific to This Standard:
3.1.1 dusting, n—the quantity of carbon that falls off the carbon artifact while in the reaction chamber and is collected in the
container at the bottom of the reaction chamber.
3.1.2 final air reactivity, n—the mass loss of the carbon artifact during the final 30 min 30 min of exposure to air in the reaction
chamber divided by the initial geometric (right cylindrical) exposed surface area of the sample, expressed as mg/cmmilligrams
-h. per centimetre squared per hour.
3.1.3 initial air reactivity, n—the mass loss of the carbon artifact during the first 30 min of exposure to air in the reaction
chamber divided by the initial geometric (right cylindrical) exposed surface area of the sample, expressed as mg/cmmilligrams
-h. per centimetre squared per hour.
3.1.4 total air reactivity, n—the total mass loss of the carbon artifact (including dusting) during the total time that the sample
is exposed to air (180 min) (180 min) in the reaction chamber divided by the initial geometric (right cylindrical) exposed surface
area of the sample, expressed as mg/cmmilligrams -h. per centimetre squared per hour.
4. Summary of Test Method
4.1 Initial, final, and total air reactivity and dusting are determined by passing air at flow rates, giving a standard velocity of
reactant gas around cylindrically shaped carbon artifacts under nearly isothermal conditions for a specified length of time. The
This test method is under the jurisdiction of ASTM Committee D02 on Petroleum Products, Liquid Fuels, and Lubricantsand is the direct responsibility of Subcommittee
D02.05 on Properties of Fuels, Petroleum Coke and Carbon Material.
Current edition approved May 1, 2010April 1, 2016. Published May 2010May 2016. Originally approved in 2000. Last previous edition approved in 20052010 as
D6559D6559 – 00a (2010).–00a (2005). DOI: 10.1520/D6559-00AR10.10.1520/D6559-00AR16E01.
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
´1
D6559 − 00a (2016)
reactivity is determined by continuously monitoring the sample mass loss. The dusting term is determined by collecting and
determining the mass of carbon particles that fall off the sample during reaction.
5. Significance and Use
5.1 The air reactivity rates are used to quantify the tendency of a carbon artifact to react with air. Carbon consumed by this
unwanted side reaction is unavailable for the primary reactions of reducing alumina to the primary metal. Air reactivity dusting
rate is used by some companies to quantify the tendency of the coke aggregate or binder coke of a carbon artifact to selectively
react with these gases. Preferential attack of the binder coke or coke aggregate of a carbon artifact by these gases causes some
carbon to fall off or dust, making the carbon unavailable for the primary reaction of reducing alumina and, more importantly,
reducing the efficiency of the aluminum reduction cell.
5.2 Comparison of air reactivity and dusting rates is useful in selecting raw materials for the manufacture of commercial anodes
for specific smelting technologies in the aluminum reduction industry.
5.3 Air reactivity rates are used for evaluating effectiveness and beneficiation processes or for research purposes.
6. Apparatus
6.1 The apparatus to be used should be as simple as possible and be commensurate with what is to be achieved, the principal
criteria being that the reaction rate is to be determined under isothermal conditions and unaffected by physical and chemical
properties inherent to the apparatus (such as gas diffusion patterns, gas temperature, exposed sample surface area, and so forth).
A typical apparatus that has been found to be suitable is illustrated in Fig. 1.
6.1.1 Furnace and Controller, capable of maintaining constant temperature within 62°C62 °C in the 100-mm100 mm region
centered on the specimen. The example apparatus of Fig. 1 employs a three zone heating element and associated controls to
accomplish this, but other methods such as tapered windings or long linear heaters are also suitable. The control thermocouple is
a grounded type and shall be located within the reaction chamber near the surface of the test sample to allow the furnace controller
to adjust to the exothermic reaction that occurs during the air reactivity test. The control thermocouple shall be positioned 44 mm
6 1 mm 1 mm from the side sample surface and centered vertically within 5 mm 5 mm of the center. The furnace shall be large
enough to accept the reaction chamber.
6.1.2 Reaction Chamber, consisting of a vertical tube constructed of a material capable of withstanding the temperature of the
reaction with sufficient inside diameter (ID) to accept the sample and sample holder while not affecting the gas flow to and from
FIG. 1 Typical Air Reactivity Apparatus
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D6559 − 00a (2016)
the sample (100(100 mm 6 25-mm25 mm ID is recommended). The reaction chamber is to be constructed with a dust collection
cup at the bottom, which is removable and capable of capturing all the dust that falls off the sample during the test. The most
common materials of construction are quartz and Inconel.
6.1.3 Sample Holders, capable of supporting the sample in the reaction chamber for the duration of the test and should be
capable of being reusable. The sample holder shall not change in mass during the test, affect the diffusion pattern of the gases to
or from the sample, limit the gas accessible surface area of the test sample, or interfere with the free fall of dust from the sample.
A typical sample holder is illustrated in Fig. 2.
6.1.4 Gas Preheat Tube, extending into the first heat zone of the reaction chamber to preheat the gases prior to entering the
reaction chamber. The length and diameter of the tube can vary as long as the gases exiting the tube are the same temperature as
the reaction chamber. The inlet gas shall exit the preheat tube downward to prevent channeling of the gas through the reaction
chamber and to prevent plugging of the preheat tube with carbon dust.
6.1.5 Balance, capable of measuring the weight of the sample and sample holder (approximately 200 g 200 g maximum)
continuously throughout the duration of the test to the nearest 0.01 g.0.01 g.
6.1.6 Gas Flow Meter, capable of monitoring the gas flow rate into the reaction chamber. All gas flow rates are to be maintained
at the rate determined for the particular test apparatus.
6.1.7 Needle Valve, to make fine adjustments to the gas flow rate.
6.1.8 Pressure Reducing Valve, to reduce the pressure of the compressed gases to near atmospheric pressure prior to entering
the gas flow meter through the needle valve.
6.1.9 Thermocouple(s), inserted into the reaction chamber to calibrate the furnace zone controllers. An optional thermocouple
may be used to monitor reaction temperatures. Some users find continuous temperature measurement of the internal reaction
chamber to be of value.
6.1.10 Calipers, or other suitable device, capable of measuring to within 0.01 mm 0.01 mm for determining the sample diameter
and height to calculate geometric surface area exposed to the test gases.
6.1.11 Optional Equipment, including but not limited to, automatic control devices, multichannel line selector, and personal
computer to automate data gathering, manipulation, reporting, and storage.
7. Reagents
7.1 Purity of Reagents—Reagent grade conforming to the specifications of the Committee on Analytical Reagents of the
American Chemical Society.
7.1.1 Nitrogen—99.95 %.
7.1.2 Air—less than 0.1 % moisture.
FIG. 2 Typical Sample Holder
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D6559 − 00a (2016)
8. Sampling
8.1 Shape the carbon specimen by coring and cutting or machining to a right cylindrical geometry, 5050 mm
...