1、Designation: C 1318 95 (Reapproved 2001)Standard 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 designati
2、on 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 (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers analysis o
3、f magnesian, dolo-mitic and high-calcium limes for total neutralizing capabilityand dissolved major oxides. Dissolved calcium and magnesiumare the major species that neutralize acid under the conditionsof the test.1.2 The test conditions are chosen to measure the acid-neutralizing capacity of both c
4、alcium hydroxide and magne-sium hydroxide contained in slaked lime. By controlling theneutralization pH at 6, magnesium hydroxide and magnesiumoxide are titrated in addition to calcium hydroxide fraction.1.3 This test method also determines the fraction of Mg ionspresent in the lime that will dissol
5、ve under lime flue gasdesulfurization (FGD) conditions. Because the Mg+ion altersFGD performance, it is important to know its concentration.1.4 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 t
6、o establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:C 25 Test Methods for Chemical Analysis of Limestone,Quicklime, and Hydrated Lime2C 50 Practice for Sampling, Sample Preparation, Pac
7、king,and Marking of Lime and Limestone Products2C 51 Terminology Relating to Lime and Limestone (asUsed by the Industry)23. Terminology3.1 DefinitionsUnless otherwise specified, for definitionsof terms used in these test methods refer to Terminology C 51.4. Summary of Test Method4.1 Lime is slaked b
8、y boiling and is reacted with acid at apH and residence time 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
9、 from the acid consumption and reported as CaO.Dissolved magnesium 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 re
10、quire a method to measure the oxidesavailable for sulfur dioxide 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 oxid
11、e and dissolved oxidevalues.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 com
12、pensator 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
13、 flasks, and variousClass A pipettes.8. Reagents8.1 1.0 Normal Hydrochloric Acid, standardize using pro-cedures in Test Methods C 25, Section 28.1This test method is under the jurisdiction of ASTM Committee C07 on Limeand is the direct responsibility of Subcommittee C07.05 on Chemical Uses.Current e
14、dition approved Nov. 10, 1995. Published February 1996.2Annual Book of ASTM Standards, Vol 04.01.1Copyright ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.8.2 Distilled Water,CO2free.8.3 Calcium and Magnesium Standard Solutions (commer-cially available or use methods in
15、 Test Methods C 25, Section31).8.4 EDTA Standard Solution (0.4 %), standardize accordingto Test Methods C 25, 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
16、carbon dioxide is held to a minimum.9.2 The sample 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
17、.10. Procedure10.1 Slaking of Lime Sample:10.1.1 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 ac
18、tively 1 min for complete slaking. Removefrom the 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 tit
19、ration by adding standard 1.0 normalhydrochloric 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
20、amount of titrant onthe buret tip and wash into the 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
21、 transfer the solution to an appropriatelysized volumetric 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 magnesiu
22、m by standardatomic absorption spectroscopy techniques.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 o
23、f 100 mL.10.3.2.2 Determine the total dissolved calcium according toTest Methods C 25, 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 C 25, Paragraph 31.6.5.Record mL of EDTA required for this titrati
24、on.11. Calculation of Results11.1 Percent Total Neutralizing 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 V
25、olume see 10.2.5!/Pipette volume for final dilution(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 weigh
26、t, g.11.3 EDTA Titration:11.3.1 Dilution Factor:Dilution 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)where:A = mL of EDTA standard solution used,B = dilution factor,C3= chemical factor = 1.399 (CaO/Ca+
27、),D = EDTA titer, mg Ca+/mL EDTA, 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.
28、3.4 Percent Dissolved Magnesium:% Dissolved Mg11 as MgO! 5 A 2 B! 3 C4(7)where:A = % total dissolved oxides,B = % dissolved calcium, andC 13182C4= 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 dat
29、a has been obtained and analyzed, astatement 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 gasdesulf
30、urization (FGD); lime; pH determination; total neutral-izing capabilityThe American Society for Testing and Materials takes no position respecting the validity of any patent rights asserted in connectionwith any item mentioned in this standard. Users of this standard are expressly advised that deter
31、mination of the validity of any suchpatent rights, and the risk of infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or
32、withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM Headquarters. Your comments will receive careful consideration at a meeting of the responsibletechnical committee, which you may attend. If you feel that your comments
33、 have not received a fair hearing you should make yourviews known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM, 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 above address or at610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website (www.astm.org).C 13183
