1、Designation: D7348 13Standard 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.1. Scope1.1 These test methods cover the determination of the massloss from solid combustion residues upon heating in an air oroxygen atmosphere
3、 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 measurement are included in thisstandard.1.3 This standar
4、d 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 limitations prior to use.2. Referenced Documents2.1 ASTM
5、 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 Elements inCombustion Residues from Coal Utilization
6、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 FluorescenceD6316 Test Method for Determination of Total, Combustibleand Carbonate Carbon in Solid Residues from Coal andCokeD6349 Test Me
7、thod for Determination of Major and MinorElements in Coal, Coke, and Solid Residues from Com-bustion of Coal and Coke by Inductively CoupledPlasmaAtomic Emission SpectrometryD6357 Test Methods for Determination of Trace Elements inCoal, Coke, and Combustion Residues from Coal Utiliza-tion Processes
8、by Inductively Coupled Plasma AtomicEmission Spectrometry, Inductively Coupled PlasmaMass Spectrometry, and Graphite Furnace Atomic AbD7582 Test Methods for Proximate Analysis of Coal andCoke by Macro Thermogravimetric AnalysisE691 Practice for Conducting an Interlaboratory Study toDetermine the Pre
9、cision 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 specimen when heated under controlledconditions of temperature,
10、 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 specimen, are determined.5. Significance and Use5.1 LOI refers
11、 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, the term LOI normally refers to masslosses in samples heate
12、d 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 combustion residues in various processesand products.5.2 If the solid
13、 combustion residue is heated to estimate 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 combustion1These test methods ar
14、e 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 Sept. 1, 2013. Published September 2013. Originallyapproved in 2007. Last previous edition approved in 200
15、8 as D7348 08E1. DOI:10.1520/D7348-13.2For 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 Document Summary page onthe ASTM website.Copyright ASTM Internat
16、ional, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1residues.3. Direct determination of unburned (combustible)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 concentra
17、tions of major andminor elements, use the heating procedure described in TestMethods D3682, D4326, and D6349, or the procedures for the750C LOI determination described in these test methods(Method A).5.4 If the solid combustion residue is heated to prepare anash for the determination of the concentr
18、ations of traceelements, use the heating procedure described in Test MethodsD3683 and D6357.NOTE 1Combustion residues produced in furnace operations or othercombustion systems can differ from the ash yield, as determined in TestMethods D3174 and D7582, because combustion conditions influence thechem
19、istry and amount of ash. Combustion causes an expulsion of allwater, the loss of carbon dioxide from carbonates, the conversion of metalsulfides into metal oxides, metal sulfates and sulfur oxides, and otherchemical reactions. Likewise, the “ash” obtained after igniting combustionresidues can differ
20、 in composition and amount from Test Methods D3174and D7582 ash yields because of different heating procedures, combustionof unburned carbon, and decomposition of materials in the residue.6. Interferences6.1 There are no known interferences for these test methods.7. Apparatus7.1 FurnaceThe apparatus
21、 shall consist of a furnace witha cavity large enough to accept multiple crucibles. The furnaceshall be constructed so the cavity is surrounded by a suitablerefractory and insulated so as to develop a uniform temperaturein all parts of the cavity but with a minimum free space. Thefurnace shall be ca
22、pable of being heated rapidly (10C/min orfaster) from ambient to 950C. The temperature shall bemonitored and maintained at values specific to each of thedeterminations. Provisions shall be made to introduce dryingand oxidizing gases and to remove products of drying,decomposition, and combustion. A r
23、ecommended flow rate isone furnace volume change per minute, but higher flow rates(that is, two furnace volumes per minute as in some otherstandard test methods for coal and coke) are acceptable. Thefurnace can be a stand alone muffle furnace or a computer-controlled macrothermogravimetric analyzer
24、(macro TGA)system. In macro TGA, a sample size of 1 g (or larger) is used.In a typical analysis, the temperature is ramped from ambientto a specific temperature and held at that temperature for aprescribed length of time. In thermogravimetric analysis, themass of a sample in a controlled atmosphere
25、is recordedrepeatedly as a function of temperature or time.7.2 Drying OvenFor determining the moisture in solidcombustion residue samples, use a drying oven with openingsfor drying gas circulation and capable of temperature regula-tion between the limits of 104 and 110C. A drying gas flowrate of app
26、roximately one volume change per minute isrecommended but higher flow rates, that is, two volumechanges per minute as in some other standard test methods forcoal and coke, are acceptable.7.3 Crucibles, use a crucible of a convenient form thatallows extensive contact between the specimen and reactant
27、gas. The crucibles can be made of porcelain, fused silica, orsimilar materials. The crucibles shall have the dimensionsspecified by the instrument 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 separat
28、e piece of apparatus.7.5 Operation of the instrumental system in its entirety shallbe verified in accordance with the manufacturers operatinginstructions.7.6 Venting EquipmentCombustion and decompositiongases evolved during the test procedures shall be vented fromthe laboratory and suitable venting
29、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 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
30、% purity) or air.9. Hazards9.1 The user shall insure acceptable documented safetyprocedures are in place for the handling of all reagents and testmaterials and for the operation of laboratory equipment speci-fied for these test methods.10. Sampling, Test Specimens, and Test Units10.1 The sample used
31、 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 required.11. Preparation of Apparatus11.1 For LOI determinations using a macro TGA, follow themanufacturers recommended procedure for verifying systemstabilit
32、y and for loading and taring the crucibles. Variousmodes of operation are possible depending on the instrumentused and the manner in which the determinations are com-pleted. The instrument can be programmed to terminate the testwhenever the test specimens and crucibles have reached aconstant mass. T
33、ypically, crucibles are weighed automaticallyat specified intervals, and the analysis is complete wheneverthree successive weighings agree within a 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 usin
34、g 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 a 1.0000 g sample.Alternately, the instrument can be programmed to allow formoisture determination by heating the test specimens for aspecified time perio
35、d (for example, 1 h) at the prescribedtemperature limits.3Burris 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 13211.2 When using a muff
36、le furnace for LOI determinations,always start the test with the muffle furnace at ambienttemperature.12. Conditioning12.1 Heat new crucibles for 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
37、 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 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 pro
38、cedure,add approximately1gofsolid combustion residue to eachsuccessive crucible and weigh. Select oxygen or air as thefurnace atmosphere and gradually raise the temperature of thefurnace at a rate such that the furnace temperature reaches 5006 10C at the end of 1 h. For Method A, continue the gradua
39、lheating until the temperature rises from 500 6 10C to 750 615C at the end of 1 h. For Method B, continue the gradualheating until the temperature rises from 500 6 10C to 950 620C at the end of 1 h. Maintain the higher temperature untilthe combustion residue test specimens reach a constant mass orfo
40、r an additional 2 h.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 cover
41、s at 104to 110C. A recommended 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
42、aremade by changing the macro TGA furnace atmosphere tooxidizing gas (see 8.1), and gradually raising the temperatureof the furnace at a rate such that the furnace temperaturereaches 500 6 10C at the end of 1 h. For Method A, continuethe gradual heating until the temperature rises from 500 610C to 7
43、50 6 15C at the end of 1 h. For Method B, continuethe gradual heating until the temperature rises from 500 610C to 950 6 20C at the end of 1 h. Maintain the highertemperature until the combustion residue test specimens reacha constant mass or for an additional 2 h.13.5 LOI can be determined in a sin
44、gle-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 thetest specimen, without a cover, into the cold furnace. Turn onthe oxidizing gas (see 8.2) and adjust t
45、he flow to approximatelyone furnace volume change per minute. Gradually raise thetemperature of the furnace at a rate such that the furnacetemperature reaches 500 6 10C at the end of 1 h. For MethodA, continue the gradual heating of the samples until thetemperature rises from 500 6 10C to 750 6 15C
46、at the endof 1 h. For Method B, continue the gradual heating until thetemperature rises from 500 6 10C to 950 6 20C at the endof 1 h. Maintain the higher temperature until the combustionresidue test specimens reach a constant mass or for anadditional 2 h.13.6 LOI can be determined in a two-step proc
47、edure using amuffle furnace and a drying oven (see 7.2). To determinemoisture, place 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)
48、through which passes a current of preheated drying gas (see8.1). Close the oven and 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 combustionresidu
49、es if the 1-h time period is insufficient to bring the testspecimen to a constant weight.) For ash determination, placethe crucible, without covers, with the dry test specimen in acold furnace. Gradually raise the temperature of the furnace ata rate such that it reaches 500 6 10C at the end of 1 h. ForMethod A, continue the gradual heating until the temperaturerises from 500 6 10C to 750 6 15C at the end of 1 h. ForMethod B, continue the gradual heating until the temperaturerises from 500 6 10C to 950 6 20C at the end of 1 h.Maintain th
