1、Designation: C 1318 95 (Reapproved 2009)1Standard Test Method forDetermination of Total Neutralizing Capability and DissolvedCalcium and Magnesium Oxide in Lime for Flue GasDesulfurization (FGD)1This standard is issued under the fixed designation C 1318; the number immediately following the designat
2、ion indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1NOTEA units statement was added editorially a
3、s new paragraph 1.4 and subsequent paragraphs were renumbered in June2009.1. Scope1.1 This test method covers analysis of magnesian, dolo-mitic and high-calcium limes for total neutralizing capabilityand dissolved major oxides. Dissolved calcium and magnesiumare the major species that neutralize aci
4、d under the conditionsof the test.1.2 The test conditions are chosen to measure the acid-neutralizing capacity of both calcium hydroxide and magne-sium hydroxide contained in slaked lime. By controlling theneutralization pH at 6, magnesium hydroxide and magnesiumoxide are titrated in addition to cal
5、cium hydroxide fraction.1.3 This test method also determines the fraction of Mg ionspresent in the lime that will dissolve under lime flue gasdesulfurization (FGD) conditions. Because the Mg+ion altersFGD performance, it is important to know its concentration.1.4 The values stated in SI units are to
6、 be regarded asstandard. No other units of measurement are included in thisstandard.1.5 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
7、 determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2C25 Test Methods for Chemical Analysis of Limestone,Quicklime, and Hydrated LimeC50 Practice for Sampling, Sample Preparation, Packag-ing, and Marking of Lime and Limestone ProductsC51 Ter
8、minology Relating to Lime and Limestone (as usedby the Industry)3. Terminology3.1 DefinitionsUnless otherwise specified, for definitionsof terms used in these test methods refer to Terminology C51.4. Summary of Test Method4.1 Lime is slaked by boiling and is reacted with acid at apH and residence ti
9、me similar to those found in full-scale FGDreaction tanks.4.2 A sample of lime is titrated with 1N hydrochloric acid,maintaining a pH of 6 for 30 min. After 30 min, the acidconsumption is recorded. The total neutralizing capacity iscalculated from the acid consumption and reported as CaO.Dissolved m
10、agnesium is determined by atomic absorptionspectrometry or by EDTA titration and reported as percentdissolved Magnesium Oxide (as MgO).5. Significance and Use5.1 There are existing lime-based flue gas desulfurizationunits in operation that require a method to measure the oxidesavailable for sulfur d
11、ioxide absorption. Dissolved magnesiumoxide varies among limes depending on the limestone sourcesand calcination conditions.6. Interferences6.1 Any substance reacting with acid under the conditionsof the test will contribute to the total oxide and dissolved oxidevalues.1This test method is under the
12、 jurisdiction of ASTM Committee C07 on Limeand is the direct responsibility of Subcommittee C07.05 on Chemical Tests.Current edition approved June 1, 2009. Published September 2009. Originallyapproved in 1995. Last previous edition approved in 2001 as C 1318 95(2001).2For referenced ASTM standards,
13、visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 1942
14、8-2959, United States.6.2 Magnesium in forms other than MgO, which dissolveunder test conditions, may affect the dissolved MgO and totaloxide value.7. Apparatus7.1 Digital Readout pH Meter, with combination electrodereadable to 0.01 pH units, or an autotitrator with an automatictemperature compensat
15、or capable of titrating to a presetendpoint (Note 1).NOTE 1Use of an automatic titrator is recommended.7.2 Stirrers and Stir Bars.7.3 Atomic Absorption Spectrometer, if not using EDTAtitration.7.4 Filtering Funnel, Type AE glass fiber paper, volumetricflasks (size as needed), 500 mL volumetric flask
16、s, and variousClass A pipettes.8. Reagents8.1 1.0 Normal Hydrochloric Acid, standardize using pro-cedures in Test Methods C25, Section 28.8.2 Distilled Water,CO2free.8.3 Calcium and Magnesium Standard Solutions (commer-cially available or use methods in Test Methods C25, Section31).8.4 EDTA Standard
17、 Solution (0.4 %), standardize accordingto Test Methods C25, Section 31.5, Standardization of EDTA.9. Sample Preparation9.1 The sampling and grinding of any lime sample shall becarried out as rapidly as possible, so that the absorption ofmoisture and carbon dioxide is held to a minimum.9.2 The sampl
18、e as received at the laboratory shall bethoroughly mixed and a representative sample with minimumweight of 100 g shall be taken and pulverized to pass a No. 50mesh sieve for analysis.9.3 The prepared sample shall be stored in a tightly cappedcontainer.10. Procedure10.1 Slaking of Lime Sample:10.1.1
19、Weigh rapidly 1.402 g of the finely pulverizedsample and brush carefully into a 250 mL Erlenmeyer flaskcontaining about 50 mL of CO2free water and immediatelystopper the flask.10.1.2 Remove the stopper. Swirl the flask, place on a hotplate and boil actively 1 min for complete slaking. Removefrom the
20、 hot plate, stopper the flask loosely and place in acold-water bath to cool to room temperature.10.2 Titration of Sample:10.2.1 Set the pH electrode, burette tip, and temperaturesensing device in place, while maintaining agitation.10.2.2 Begin the titration by adding standard 1.0 normalhydrochloric
21、acid solution. Titrate to and maintain a pH of 6within 0.4 pH units for 30 min (Note 2). Time begins frominitial addition of acid.NOTE 2When doing a manual titration, the increment of acid additionmay require the use of partial drops (suspend a small amount of titrant onthe buret tip and wash into t
22、he titration flask with CO2free distilled water)to avoid exceeding the 0.4 unit limit of pH 6.10.2.3 Record the amount of acid consumed after 30 min.10.2.4 Filter the solution and rinse the flask thoroughly withCO2free distilled water.10.2.5 Carefully transfer the solution to an appropriatelysized v
23、olumetric flask, add approximately 10 mL of 1:1hydrochloric acid, and dilute to volume.10.3 Determination of Dissolved Oxides:10.3.1 Atomic Absorption:10.3.1.1 From the diluted solution make the required dilu-tions and determine the dissolved magnesium by standardatomic absorption spectroscopy techn
24、iques.10.3.1.2 Calculate the dissolved magnesium as MgO ac-cording to 11.2.10.3.2 EDTA Titration:10.3.2.1 From the diluted solution pipette 20 mL of sampleinto a 500 mL Erlenmeyer flask and dilute with CO2freedistilled water to an approximate volume of 100 mL.10.3.2.2 Determine the total dissolved c
25、alcium according toTest Methods C25, Paragraph 31.6.4. Record mL of EDTArequired for titration.10.3.2.3 Repeat 10.3.2 and determine the total dissolvedoxides according to Test Methods C25, Paragraph 31.6.5.Record mL of EDTA required for this titration.11. Calculation of Results11.1 Percent Total Neu
26、tralizing Capability (TNC):% TNC as CaO! 5A 3 B 3 C1W(1)where:A = mL HCl used in 10.2.3,B = normality HCl,C1= chemical factor = 2.804 (mequi of CaO/10), andW = sample weight, g.11.2 Atomic Absorption:11.2.1 Dilution Factor:Dilution factor5 Initial Volume see 10.2.5!/Pipette volume for final dilution
27、(2)11.2.2 Percent Dissolved Magnesium:% Dissolved Mg11 as MgO!5A 3 B 3 C23 DW 3 1000(3)where:A = concentration of magnesium from AA, ppm Mg+,B = dilution factor,C2= chemical factor = 1.658 (MgO/Mg+),D = final dilution volume, mL, andW = sample weight, g.11.3 EDTA Titration:11.3.1 Dilution Factor:Dil
28、ution factor 5 Initial Volume see 10.2.5!/titration volume 20 mL!(4)11.3.2 Percent Dissolved Calcium:% Dissolved Ca11 as CaO! 5A 3 B 3 C33 DW 3 10(5)C 1318 95 (2009)12where:A = mL of EDTA standard solution used,B = dilution factor,C3= chemical factor = 1.399 (CaO/Ca+),D = EDTA titer, mg Ca+/mL EDTA,
29、 andW = sample weight, g.11.3.3 Percent Total Dissolved Oxides (TDO):% TDO as CaO! 5A 3 B 3 C33 DW 3 10(6)where:A = mL of EDTA standard solution used,B = dilution factor,C3= chemical factor = 1.399 (CaO/Ca+),D = EDTA titer, mg Ca+/mL EDTA, andW = sample weight, g.11.3.4 Percent Dissolved Magnesium:%
30、 Dissolved Mg11 as MgO! 5 A 2 B! 3 C4(7)where:A = % total dissolved oxides,B = % dissolved calcium, andC4= chemical factor = 0.7188 (MgO/CaO).12. Precision and Bias12.1 The precision and bias of this test method have notbeen determined.12.2 When sufficient data has been obtained and analyzed, astate
31、ment of precision will be provided.12.3 The user is cautioned to verify by the use of referencematerials, if available, that the bias of the test method isadequate for the contemplated use.13. Keywords13.1 dissolved calcium; dissolved magnesium; flue gasdesulfurization (FGD); lime; pH determination;
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35、views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).C 1318 95 (2009)13
