1、Designation: D7348 081Standard Test Methods forLoss on Ignition (LOI) of Solid Combustion Residues1This standard is issued under the fixed designation D7348; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision
2、. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1NOTEEq 4 was editorially corrected in May 2011.1. Scope1.1 These test methods cover the determination of the massloss from solid combustion re
3、sidues upon heating in an air oroxygen atmosphere to a prescribed temperature. The mass losscan be due to the loss of moisture, carbon, sulfur, and so forth,from the decomposition or combustion of the residue.1.2 The values stated in SI units are to be regarded asstandard. No other units of measurem
4、ent are included in thisstandard.1.3 This standard does not purport to address all of thesafety 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 limitat
5、ions prior to use.2. Referenced Documents2.1 ASTM Standards:2D121 Terminology of Coal and CokeD3174 Test Method for Ash in the Analysis Sample of Coaland Coke from CoalD3180 Practice for Calculating Coal and Coke Analysesfrom As-Determined to Different BasesD3682 Test Method for Major and Minor Elem
6、ents inCombustion Residues from Coal Utilization ProcessesD3683 Test Method for Trace Elements in Coal and CokeAsh by Atomic AbsorptionD4326 Test Method for Major and Minor Elements in Coaland Coke Ash By X-Ray FluorescenceD5142 Test Methods for ProximateAnalysis of theAnalysisSample of Coal and Cok
7、e by Instrumental Procedures3D6316 Test Method for Determination of Total, Combus-tible and Carbonate Carbon in Solid Residues from Coaland CokeD6349 Test Method for Determination of Major and MinorElements in Coal, Coke, and Solid Residues from Com-bustion of Coal and Coke by Inductively CoupledPla
8、smaAtomic Emission SpectrometryD6357 Test Methods for Determination of Trace Elementsin Coal, Coke, and Combustion Residues from CoalUtilization Processes by Inductively Coupled PlasmaAtomic Emission Spectrometry, Inductively CoupledPlasma Mass Spectrometry, and Graphite Furnace AtomicAbE691 Practic
9、e for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method3. Terminology3.1 DefinitionsFor definitions of terms used in these testmethods, refer to Terminology D121.4. Summary of Test Method4.1 Loss on ignition (LOI) is determined by measuring theloss in mass of the test sp
10、ecimen when heated under controlledconditions of temperature, time, atmosphere, specimen mass,and equipment specifications. The LOI can be determined bymeasuring the mass loss in a single procedure or in a two-stepprocedure in which mass losses, equivalent to the moisture andash values of the test s
11、pecimen, are determined.5. Significance and Use5.1 LOI refers to the mass loss of a combustion residuewhenever it is heated in an air or oxygen atmosphere to hightemperatures. In the cement industry, use of the term LOInormally refers to a mass loss in a sample heated to 950C. Tocombustion engineers
12、, the term LOI normally refers to masslosses in samples heated to temperatures normally less than950C. These test methods establish a procedure for determin-ing LOI values for combustion residues heated to 750C or950C. LOI values from these test methods can be used byindustries that utilize combusti
13、on residues in various processesand products.1These test methods are under the jurisdiction ofASTM Committee D05 on Coaland Coke and is the direct responsibility of Subcommittee D05.29 on MajorElements in Ash and Trace Elements of Coal.Current edition approved Oct. 15, 2008. Published October 2008.
14、Originallyapproved in 2007. Last previous edition approved in 2007 as D734807. DOI:10.1520/D7348-08.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service as serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Do
15、cument Summary page onthe ASTM website.3Withdrawn. The last approved version of this historical standard is referencedon www.astm.org.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.5.2 If the solid combustion residue is heated to es
16、timate thecombustible or unburned carbon in the sample, it has beenshown that LOI and estimation of unburned carbon do notnecessarily agree well with each other and that LOI should notbe used as an estimate of unburned carbon in all combustionresidues.4. Direct determination of unburned (combustible
17、)carbon can be carried out using Test Method D6316.5.3 If the solid combustion residue is heated to prepare anash for the determination of the concentrations of major andminor elements, use the heating procedure described in TestMethods D3682, D4326, and D6349, or the procedures for the750C LOI dete
18、rmination described in these test methods(Method A).5.4 If the solid combustion residue is heated to prepare anash for the determination of the concentrations of traceelements, use the heating procedure described in Test MethodsD3683 and D6357.NOTE 1Combustion residues produced in furnace operations
19、 or othercombustion systems can differ from the ash yield, as determined in TestMethods D3174 and D5142, because combustion conditions influence thechemistry and amount of ash. Combustion causes an expulsion of allwater, the loss of carbon dioxide from carbonates, the conversion of metalsulfides int
20、o metal oxides, metal sulfates and sulfur oxides, and otherchemical reactions. Likewise, the “ash” obtained after igniting combustionresidues can differ in composition and amount from Test Methods D3174and D5142 ash yields because of different heating procedures, combustionof unburned carbon, and de
21、composition of materials in the residue.6. Interferences6.1 There are no known interferences for these test methods.7. Apparatus7.1 FurnaceThe apparatus shall consist of a furnace witha cavity large enough to accept multiple crucibles. The furnaceshall be constructed so the cavity is surrounded by a
22、 suitablerefractory and insulated so as to develop a uniform temperaturein all parts of the cavity but with a minimum free space. Thefurnace shall be capable of being heated rapidly (10C/min orfaster) from ambient to 950C. The temperature shall bemonitored and maintained at values specific to each o
23、f thedeterminations. Provisions shall be made to introduce dryingand oxidizing gases and to remove products of drying, decom-position, and combustion. A recommended flow rate is onefurnace volume change per minute, but higher flow rates (thatis, two furnace volumes per minute as in some other standa
24、rdtest methods for coal and coke) are acceptable. The furnace canbe a stand alone muffle furnace or a computer-controlledmacrothermogravimetric analyzer (macro TGA) system. Inmacro TGA, a sample size of 1 g (or larger) is used. In a typicalanalysis, the temperature is ramped from ambient to a specif
25、ictemperature and held at that temperature for a prescribed lengthof time. In thermogravimetric analysis, the mass of a sample ina controlled atmosphere is recorded repeatedly as a function oftemperature or time.7.2 Drying OvenFor determining the moisture in solidcombustion residue samples, use a dr
26、ying oven with openingsfor drying gas circulation and capable of temperature regula-tion between the limits of 104 and 110C. A drying gas flowrate of approximately one volume change per minute isrecommended but higher flow rates, that is, two volumechanges per minute as in some other standard test m
27、ethods forcoal and coke, are acceptable.7.3 Crucibles, use a crucible of a convenient form thatallows extensive contact between the specimen and reactantgas. The crucibles can be made of porcelain, fused silica, orsimilar materials. The crucibles shall have the dimensionsspecified by the instrument
28、manufacturer.7.4 Balance, sensitive to 0.1 mg. In the macro TGA, thebalance is an integral part of the system. For other systems, thebalance is a separate piece of apparatus.7.5 Operation of the instrumental system in its entirety shallbe verified in accordance with the manufacturers operatinginstru
29、ctions.7.6 Venting EquipmentCombustion and decompositiongases evolved during the test procedures shall be vented fromthe laboratory and suitable venting equipment shall be installedin the vicinity of the apparatus.8. Reagents and Materials8.1 Drying GasesAir dried to a moisture content of 1.9mg/L or
30、 less (dew point 10C or less). Nitrogen (99.5 %purity) is normally used with the macro TGA system. Argoncan also be used.8.2 Oxidizing GasesOxygen (99.5 % purity) or air.9. Hazards9.1 The user shall insure acceptable documented safetyprocedures are in place for the handling of all reagents and testm
31、aterials and for the operation of laboratory equipment speci-fied for these test methods.10. Sampling, Test Specimens, and Test Units10.1 The sample used for analysis shall be thoroughlymixed and of such fineness to pass through a 250-m (No. 60)sieve. Pulverizing the sample to this fineness is requi
32、red.11. Preparation of Apparatus11.1 For LOI determinations using a macro TGA, follow themanufacturers recommended procedure for verifying systemstability and for loading and taring the crucibles. Variousmodes of operation are possible depending on the instrumentused and the manner in which the dete
33、rminations are com-pleted. The instrument can be programmed to terminate the testwhenever the test specimens and crucibles have reached aconstant mass. Typically, crucibles are weighed automaticallyat specified intervals, and the analysis is complete wheneverthree successive weighings agree within a
34、 plateau deviationspecified for the instrument. Constant mass is defined as a pointwhere the mass change is # 0.05 % of a nine-minute period,either by using three successive weighings (for some TGAs) ora fixed nine-minute period (for some TGAs). This mass changeof 0.05% is equivalent to 0.0005 g for
35、 a 1.0000 g sample.Alternately, the instrument can be programmed to allow for4Burris S.C. , Li, D., and Riley J.T, “Comparison of Heating Losses and MacroThermogravimetric Analysis Procedures for Estimating Unburned Carbon in Com-bustion Residues,” Energy Fuels Vol 19 2005, pp. 1493-1502.D7348 0812m
36、oisture determination by heating the test specimens for aspecified time period (for example, 1 h) at the prescribedtemperature limits.11.2 When using a muffle furnace for LOI determinations,always start the test with the muffle furnace at ambienttemperature.12. Conditioning12.1 Heat new crucibles fo
37、r use in these test methods underthe conditions of the test and cool before use.13. Procedure13.1 In these procedures Method A refers to LOI determi-nations at 750C whereas Method B refers to LOI determina-tions at 950C.13.2 For LOI determinations using a macro TGA, theanalyses are normally complete
38、 when the sample reaches aconstant mass as defined in the instrumental operating param-eters. (See 11.1.)13.3 For LOI determinations using a single-step procedure,add approximately1gofsolid combustion residue to eachsuccessive crucible and weigh. Select oxygen or air as thefurnace atmosphere and rai
39、se the temperature of the furnace ata rate such that the furnace temperature reaches 450 to 500Cat the end of 1 h and 750C (Method A) or 950C (Method B)at the end of the second h. Maintain the temperature for anadditional two hours or until the combustion residue testspecimens reach a constant mass.
40、13.4 For LOI determinations using a two-step procedure,add approximately1gofsolid combustion residue to eachsuccessive crucible and weigh. For moisture determinationswith the macro TGA, turn on the drying gas (see 8.1) and heatthe weighed test specimens in crucibles without covers at 104to 110C. A r
41、ecommended flow rate is one furnace volumechange per minute, but higher flow rates (that is, two furnacevolumes per minute as in other standard test methods for coaland coke) are acceptable. Ash determinations on the residues(dried test specimens) from the moisture determination aremade by changing
42、the macro TGA furnace atmosphere tooxidizing gas (see 8.1), and raising the temperature of thefurnace at a rate such that the furnace temperature reaches 450to 500C at the end of 1 h and 750C (Method A) or 950C(Method B) at the end of the second h. Maintain the tempera-ture for an additional two hou
43、rs or until the combustion residuetest specimens reach a constant mass.13.5 LOI can be determined in a single-step procedure usinga muffle furnace (see 7.1). Place approximately1gofcombustion residue into a preweighed crucible and weigh thetest specimen to the nearest 0.1 mg. Place the crucible with
44、 thetest specimen, without a cover, into the cold furnace. Turn onthe oxidizing gas (see 8.2) and adjust the flow to approximatelyone furnace volume change per minute. Raise the temperatureof the furnace at a rate such that the furnace temperaturereaches 450 to 500C at the end of 1 h and 750C (Metho
45、d A)or 950C (Method B) at the end of the second h. Maintain thetemperature for an additional two hours or until the combustionresidue test specimens reach a constant mass.13.6 LOI can be determined in a two-step procedure using amuffle furnace and a drying oven (see 7.2). To determinemoisture, place
46、 approximately1gofcombustion residue intoa preweighed crucible and weigh the test specimen to thenearest 0.1 mg. Place the crucible with the test specimen,without a cover, into the preheated drying oven (104 to 110C)through which passes a current of preheated drying gas (see8.1). Close the oven and
47、heat for 1 h. Remove the test specimencrucibles, cover immediately, allow to cool to ambient tem-perature in a desiccator, and weigh. (Additional heatings andweighings may be necessary for some solid combustionresidues if the 1-h time period is insufficient to bring the testspecimen to a constant we
48、ight.) For ash determination, placethe crucible, without covers, with the dry test specimen in acold furnace. Raise the temperature of the furnace at a rate suchthat it reaches 450 to 500C at the end of 1 h and 750C(Method A) or 950C (Method B) at the end of the second h.Maintain the temperature for
49、 an additional two hours or untilthe combustion residue test specimens reach a constant mass.13.7 If the solid combustion residue is heated to prepare anash for the determination of the concentrations of major andminor elements, use the heating procedure described in TestMethods D3682 (7.1), D4326 (7.1), and D6349 (9.2), or the750C procedure (Method A) described previously.13.8 If the solid combustion residue is heated to prepare anash for the determination of the concentrations of traceelements, use the heating procedure described in Test Me
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