1、Designation: D 7348 07Standard Test Methods forLoss on Ignition (LOI) of Solid Combustion Residues1This standard is issued under the fixed designation D 7348; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revisio
2、n. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) 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 atmosph
3、ere 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 given in SI units are to be considered as thestandard.1.3 This standard does not purport to address all of thesafety conce
4、rns, 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 Standards:2D 121 Terminology of Coal and CokeD 3174
5、 Test Method forAsh in theAnalysis Sample of Coaland Coke from CoalD 3180 Practice for Calculating Coal and Coke Analysesfrom As-Determined to Different BasesD 3682 Test Method for Major and Minor Elements inCombustion Residues from Coal Utilization ProcessesD 3683 Test Method for Trace Elements in
6、Coal and CokeAsh by Atomic AbsorptionD 4326 Test Method for Major and Minor Elements in Coaland Coke Ash By X-Ray FluorescenceD 5142 Test Methods for Proximate Analysis of the Analy-sis Sample of Coal and Coke by Instrumental ProceduresD 6316 Test Method for Determination of Total, Combus-tible and
7、Carbonate Carbon in Solid Residues from Coaland CokeD 6349 Test Method for Determination of Major and MinorElements in Coal, Coke, and Solid Residues from Com-bustion of Coal and Coke by Inductively CoupledPlasmaAtomic Emission SpectrometryD 6357 Test Methods for Determination of Trace Elementsin Co
8、al, Coke, and Combustion Residues from CoalUtilization Processes by Inductively Coupled PlasmaAtomic Emission Spectrometry, Inductively CoupledPlasma Mass Spectrometry, and Graphite Furnace AtomicAb3. Terminology3.1 DefinitionsFor definitions of terms used in these testmethods, refer to Terminology
9、D 121.4. 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, time, atmosphere, specimen mass,and equipment specifications. The LOI can be determined bymeasuring the mass loss in a sing
10、le 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 to the mass loss of a combustion residuewhen it is heated in an air or oxygen atmosphere to hightemperatures. In the cement
11、 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 heated to temperatures normally less than950C. These test methods establish a procedure for determin-ing LOI values for combustion re
12、sidues heated to 950C. LOIvalues from these test methods can be used by industries thatutilize combustion residues in various processes and products.5.2 If the solid combustion residue is heated to estimate thecombustible or unburned carbon in the sample, it has beenshown that LOI and estimation of
13、unburned carbon do notnecessarily agree well with each other and that LOI should notbe used as an estimate of unburned carbon in all combustionresidues.3. Direct determination of unburned (combustible)carbon can be carried out using Test Method D 6316.5.3 If the solid combustion residue is heated to
14、 prepare anash for the determination of the concentrations of major and1These 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 May 1, 2007.
15、Published May 2007.2For 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.3S.C. Burris, D. Li, and J.T.Riley, “Compa
16、rison of Heating Losses and MacroThermogravimetric Analysis Procedures for Estimating Unburned Carbon in Com-bustion Residues,” Energy Fuels, Vol 19, 2005, pp. 1493-1502.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.minor elements,
17、 use the heating procedure described in TestMethods D 3682, D 4326, and D 6349.5.4 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 MethodsD 3683 and D 6357.NOTE 1Combustion residues p
18、roduced in furnace operations or othercombustion systems can differ from the ash yield, as determined in TestMethods D 3174 and D 5142, because combustion conditions influencethe chemistry and amount of ash. Combustion causes an expulsion of allwater, the loss of carbon dioxide from carbonates, the
19、conversion of metalsulfides into 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 D 3174and D 5142 ash yields because of different heating procedures, com
20、bus-tion of 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 shall consist of a furnace witha cavity large enough to accept multiple crucibles. The furnaceshall be construct
21、ed 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 capable of being heated rapidly (10C/min orfaster) from ambient to 950C. The temperature shall bemonitored and main
22、tained at values specific to each of 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
23、 per minute as in some other standardtest 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
24、 is ramped from ambient to a specifictemperature 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 solidc
25、ombustion 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 approximately one volume change per minute isrecommended but higher flow rates, that is, two volumechanges per minu
26、te 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 reactantgas. The crucibles can be made of porcelain, fused silica, orsimilar materials. The crucibles shall have the dim
27、ensionsspecified 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 separate piece of apparatus.7.5 Operation of the instrumental system in its entirety shallbe verified in accordance wit
28、h the manufacturers operatinginstructions.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
29、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 % purity) or air.9. Hazards9.1 The user shall insure acceptable documented safetyprocedures are in place for the
30、 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 for analysis shall be thoroughlymixed and of such fineness to pass through a 250-m (No. 60)sieve. Pulverizing t
31、he sample to this fineness is required.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 instrumentus
32、ed and the manner in which the determinations are com-pleted. The instrument can be programmed to terminate the testwhen the test specimens and crucibles have reached a constantweight. Typically, crucibles are weighed automatically atspecified intervals, and the analysis is complete when twosuccessi
33、ve weighings agree within a plateau deviation specifiedfor the instrument. Alternately, the instrument can be pro-grammed to allow for moisture determination by heating thetest specimens for a specified time period (for example, 1 h) atthe prescribed temperature limits.11.2 When using a muffle furna
34、ce 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 For LOI of moisture and ash, in analyses of solidcombustion residu
35、es using a macro TGA, the analyses arenormally complete when the sample reaches a constant weightas defined in the instrumental operating parameters.13.2 For LOI determinations using a single-step procedure,add approximately1gofsolid combustion residue to eachsuccessive crucible and weigh. Select ox
36、ygen or air as thefurnace atmosphere and raise the temperature of the furnace ata rate such that it reaches 450 to 500C at the end of1handD7348072950C at the end of the second h. Continue to heat and weighat 950C until the combustion residue test specimens reach aconstant weight or an additional 2 h
37、.13.3 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
38、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 aremade by changing
39、 the macro TGA furnace atmosphere tooxidizing gas (see 8.1), and raising the temperature of thefurnace at a rate such that it reaches 450 to 500C at the end of1 h and 950C at the end of the second h. Continue to heat andweigh at 950C until the combustion residue test specimensreach a constant weight
40、 or an additional 2 h.13.4 LOI can be determined in a single-step procedure usinga muffle furnace (see 7.1). Place approximately1gofcombustion residue in a preweighed crucible and weigh the testspecimen to the nearest 0.1 mg. Place the crucible with the testspecimen, without a cover, in the cold fur
41、nace. Turn on theoxidizing 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 it reaches 450 to 500C at theend of 1 h and 950C at the end of the second h. Continue toheat and weigh at 950C until the combusti
42、on residue testspecimens reach a constant weight or an additional 2 h.13.5 LOI can be determined in a two-step procedure using amuffle furnace and a drying oven (see 7.2). To determinemoisture, place approximately1gofcombustion residue in apreweighed crucible and weigh the test specimen to the neare
43、st0.1 mg. Place the crucible with the test specimen, without acover, in the in the preheated drying oven (104 to 110C)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-p
44、erature 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 weight.) For ash determination, placethe crucible, without covers, with the dry test specimen in aco
45、ld furnace. Raise the temperature of the furnace at a rate suchthat it reaches 450 to 500C at the end of 1 h and 950C at theend of the second h. Continue to heat and weigh at 950C untilthe combustion residue test specimens reach a constant weightor an additional 2 h.13.6 If the solid combustion resi
46、due is heated to prepare anash for the determination of the concentrations of major andminor elements, use the heating procedure described in TestMethods D 3682 (7.1), D 4326 (7.1), and D 6349 (9.2).13.7 If the solid combustion residue is heated to prepare anash for the determination of the concentr
47、ations of traceelements, use the heating procedure described in Test MethodsD 3683 (9.1) and D 6357 (9.1).14. Calculation of Results14.1 With a computer-controlled macro TGA, the computeris normally programmed to perform calculations automatically.The equations used in the calculations are as listed
48、 in thefollowing sections.14.2 Calculate the LOI percentage from the single-stepprocedure as follows:LOI 5 W 2 B!/W 3 100 (1)Where:W = weight of test specimen used, g, andB = weight of test specimen after heating at 950C, g.14.3 Calculate the LOI percentage from the two-step pro-cedure as follows:M
49、5 W 2 C!/W 3 100 (2)Ash 5 D/W 3 100 (3)LOI 5 W 2 C 2 D!/W 3 100 (4)Where:M = percent moisture as determined in the test specimenW = weight of test specimen used, g;C = weight of test specimen after drying in moisture test,g;D = weight of ash residue after heating at 950C, g; andLOI = percent loss on ignition as determined in the testspecimen.15. Report15.1 For reporting analyses to other than the as-determinedbasis, refer to Practice D 3180.16. Precision and Bias16.1 PrecisionThe precision data of these test method forthe determination of L
