ASTM D6558-00a

Standard Test Method for Determination of TGA CO₂ Reactivity of Baked Carbon Anodes and Cathode Blocks

SCOPE
1.1 This test method covers the thermogravimetric (TGA) determination of CO2 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 the 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: 09-Dec-2000
• 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

Relations

• Replaces: ASTM D6558-00 - Standard Test Method for Determination of TGA CO₂ Reactivity of Baked Carbon Anodes and Cathode Blocks
• Effective Date: 10-Dec-2000
• Replaced By: ASTM D6558-00a(2005) - Standard Test Method for Determination of TGA CO<inf>2</inf> Reactivity of Baked Carbon Anodes and Cathode Blocks
• Effective Date: 01-May-2005

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NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.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
An American National Standard
Designation:D6558–00a
Standard Test Method for
Determination of TGACO Reactivity of Baked Carbon
2
1
Anodes and Cathode Blocks
This standard is issued under the fixed designation D 6558; 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 (e) indicates an editorial change since the last revision or reapproval.
1. Scope reaction chamber divided by the initial geometric (right cylin-
drical) exposed surface area of the sample, expressed as
1.1 This test method covers the thermogravimetric (TGA)
2
mg/cm -h.
determination of CO reactivity and dusting of shaped carbon
2
3.1.3 initial CO reactivity, n—the mass loss of the carbon
2
anodes and cathode blocks used in the aluminum reduction
artifact during the first 30 min of exposure to CO in the
industry.The apparatus selection covers a significant variety of 2
reaction chamber divided by the initial geometric (right cylin-
types with various thermal conditions, sample size capability,
drical) exposed surface area of the sample, expressed as
materials of construction, and procedures for determining the
2
mg/cm -h.
mass loss and subsequent rate of reaction. This test method
3.1.4 total CO reactivity, n—the total mass loss of the
2
standardizes the variables of sample dimensions, reaction
carbon artifact (including dusting) during the total time that the
temperature, gas velocity over the exposed surfaces, and
sample is exposed to CO (420 min) in the reaction chamber
2
reactiontimesuchthatresultsobtainedondifferentapparatuses
divided by the initial geometric (right cylindrical) exposed
are correlatable.
2
surface area of the sample, expressed as mg/cm -hr.
1.2 The values stated in SI units are to be regarded as the
standard.
4. Summary of Test Method
1.3 This standard does not purport to address all of the
4.1 Initial, final, and total CO reactivity and dusting are
2
safety concerns, if any, associated with its use. It is the
determined by passing carbon dioxide gas at flow rates giving
responsibility of the user of this standard to establish appro-
a standard velocity of reactant gas around cylindrically shaped
priate safety and health practices and determine the applica-
carbon artifacts under isothermal conditions for a specified
bility of regulatory limitations prior to use.
length of time. The reactivity is determined by continuously
2. Referenced Documents monitoring the sample mass loss. The dusting term is deter-
mined by collecting and determining the mass of carbon
2.1 ASTM Standards:
particles that fall off the sample during reaction.
D 6353 Guide for Sampling Plan and Core Sampling of
2
Prebaked Anodes Used in Aluminum Production
5. Significance and Use
D 6354 Guide for Sampling Plan and Core Sampling of
2 5.1 The CO reactivity rates are used to quantify the
2
Carbon Cathode Blocks Used in Aluminum Production
tendency of a carbon artifact to react with carbon dioxide.
E 691 Practice for Conducting an Interlaboratory Study to
3 Carbon consumed by these unwanted side reactions is unavail-
Determine the Precision of a Test Method
able for the primary reactions of reducing alumina to the
3. Terminology primary metal. CO dusting rates are used to quantify the
2
tendency of the coke aggregate or binder coke of a carbon
3.1 Definitions of Terms Specific to This Standard:
artifact to selectively react with these gases. Preferential attack
3.1.1 dusting, n—that quantity of carbon that falls off the
of the binder coke or coke aggregate of a carbon artifact by
carbonartifactwhileinthereactionchamberandiscollectedin
these gases causes some carbon to fall off or dust, making the
the container at the bottom of the reaction chamber.
carbon unavailable for the primary reaction of reducing alu-
3.1.2 final CO reactivity, n—the mass loss of the carbon
2
mina and, more importantly, reducing the efficiency of the
artifact during the final 30 min of exposure to CO in the
2
aluminum reduction cell.
5.2 ComparisonofCO reactivityanddustingratesisuseful
2
1
This test method is under the jurisdiction of ASTM Committee D02 on
in selecting raw materials for the manufacture of commercial
Petroleum Products and Lubricants and is the direct responsibility of Subcommittee
anodes for specific smelting technologies in the aluminum
D02.05 on The Properties of Fuels, Petroleum Coke and Carbon Material.
Current edition approved Dec. 10, 2000. Published January 2001. Originally reduction industry.
published as D 6558 – 00. Last previous edition D 6558 – 00.
5.3 CO reactivityratesareusedforevaluatingeffectiveness
2
2
Annual Book of ASTM Standards, Vol 05.04.
and beneficiation processes or for research purposes.
3
Annual Book of ASTM Standards
...