1、Designation: E 372 01 (Reapproved 2006)Standard Test Method forDetermination of Calcium and Magnesium in MagnesiumFerrosilicon1This standard is issued under the fixed designation E 372; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revisio
2、n, 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 the chemical analysis of mag-nesium ferrosilicon having chemical compositions
3、within thefollowing limits:Element Concentration Range, %Aluminum 2.0 maxCalcium 0.25 to 3.00Carbon 0.50 maxCerium 1.0 maxChromium 0.50 maxMagnesium 2.00 to 12.00Manganese 1.0 maxSilicon 40.00 to 55.00Sulfur 0.025 maxTitanium 0.2 max1.2 This standard does not purport to address all of thesafety conc
4、erns, 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. For generalprecautions to be observed in this test method, refer toPractices E50.
5、2. Referenced Documents2.1 ASTM Standards:2E29 Practice for Using Significant Digits in Test Data toDetermine Conformance with SpecificationsE32 Practices for Sampling Ferroalloys and SteelAdditivesfor Determination of Chemical CompositionE50 Practices for Apparatus, Reagents, and Safety Consid-erat
6、ions for Chemical Analysis of Metals, Ores, andRelated MaterialsE60 Practice for Analysis of Metals, Ores, and RelatedMaterials by Molecular Absorption SpectrometryE 173 Practice for Conducting Interlaboratory Studies ofMethods for Chemical Analysis of Metals33. Significance and Use3.1 This test met
7、hod for the chemical analysis of metals andalloys is primarily intended to test such materials for compli-ance with compositional specifications. It is assumed that allwho use this test method will be trained analysts capable ofperforming common laboratory procedures skillfully andsafely. It is expe
8、cted that work will be performed in a properlyequipped laboratory.4. Apparatus, Reagents, and Photometric Practice4.1 Apparatus and reagents required for each determinationare listed in separate sections preceding the procedure. Theapparatus, standard solutions, and certain other reagents usedin mor
9、e than one procedure are referred to by number and shallconform to the requirements prescribed in Practices E50,except that photometers shall conform to the requirementsprescribed in Practice E60.4.2 Photometric practice prescribed in this test method shallconform to Practice E60.5. Sampling5.1 For
10、procedures for sampling the material, refer toMethods E32.6. Rounding Calculated Values6.1 Calculated values shall be rounded to the desired num-ber of places as directed in 3.4 to 3.6 of Practice E29.1This test method is under the jurisdiction of ASTM Committee E01 onAnalytical Chemistry for Metals
11、, Ores and Related Materials and are the directresponsibility of Subcommittee E01.01 on Iron, Steel, and Ferroalloys.Current edition approved Nov. 1, 2006. Published November 2006. Originallyapproved in 1976. Redesignated E 372 in 1980. Last previous edition approved in2001 as E 372 01.2For referenc
12、ed ASTM standards, 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.3Withdrawn.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C7
13、00, West Conshohocken, PA 19428-2959, United States.7. Interlaboratory Studies7.1 This test method has been evaluated in accordance withPractice E 173, unless otherwise noted in the precision and biassection.CALCIUM AND MAGNESIUM BY THE(ETHYLENEDINITRILO)TETRAACETIC ACID(EDTA) TITRIMETRIC METHOD8. S
14、cope8.1 This test method covers the determination of magne-sium in concentrations from 2 to 12 % and calcium inconcentrations from 0.25 to 3.0 %.9. Summary of Test Method9.1 After dissolution of the sample in nitric and hydrofluoricacids, an ammonium hydroxide precipitation is made to sepa-rate othe
15、r elements from calcium and magnesium. Calcium,and magnesium plus calcium are titrated in separate aliquotportions after adding triethanolamine and potassium cyanide tomask residual traces of iron, copper, nickel, manganese, andaluminum that may be present. Calcium is titrated withdisodium (ethylene
16、dinitrilo)tetraacetate (EDTA) at pH 12.Magnesium plus calcium is titrated with EDTA at pH 10.0 andthe magnesium concentration is calculated by correcting for thevolume of EDTA required to titrate the calcium.10. Interferences10.1 Provision is made for the removal or masking ofinterfering elements or
17、dinarily present in magnesium ferrosili-con.11. Apparatus11.1 Beakers, TFE-fluorocarbon 500-mL.11.2 pH MeterApparatus No. 3A.12. Reagents12.1 Ammonium Chloride Buffer Solution (pH 10.0)Dissolve 60 g of ammonium chloride (NH4Cl) in 200 mL ofwater, add 570 mL of NH4OH, and dilute to 1 L.12.2 Calcium,
18、Standard Solution (1 mL = 0.2002 mg Ca)Dissolve 0.5000 g of calcium carbonate (CaCO3) (purity:99.9 % min) in 100 mL of HCl (5+95). Boil 1 min, cool,transfer to a 1-L volumetric flask, dilute to volume, and mix.12.3 Disodium Ethylenedinitrilo-Tetraacetate Dihydrate(EDTA), Standard Solution (0.005 M)P
19、repare a solution asdirected for Reagent No. 22, using 1.8613 g instead of thespecified weight.12.3.1 Standardize the solution as follows: Using a pipet,tranfer 25 mL of the calcium solution (1 mL = 0.2002 mg Ca)to a 250-mL beaker, add 1 mL of MgCl2solution and 100 mLof water, and proceed as directe
20、d in 13.4.NOTE 1Containers used for the storage of dilute solutions of EDTAshould be pretreated with a hot alkaline EDTA solution (10 g/L), andrinsed with water.12.3.2 Calculate the calcium equivalent of the EDTA solu-tion as follows:Calcium equivalent, mg/mL 5 A/B (1)where:A = calcium, mg, andB = E
21、DTAsolution required to titrate the calcium solution,mL.12.3.3 Calculate the magnesium equivalent of the solutionas follows:Magnesium equivalent, mg/mL 5 C 3 0.6068 (2)where C = calcium equivalent (12.3.2).12.4 Eriochrome Black-T Indicator Solution (6 g/L ofmethanol)Dissolve 0.3 g of Eriochrome Blac
22、k-T and1gofsodium borate decahydrate (Na2B4O710H2O) in 50 mL ofmethanol. Do not use a solution that has stood for more than 8h.12.5 Hydroxy Naphthol Blue MixtureAdd 1.0 g of indi-cator to 100 g NaCl and mix thoroughly.12.6 Magnesium Chloride (2.5 g/L)Dissolve 0.25 g ofmagnesium chloride hexahydrate
23、(MgCl26H2O) in 50 mL ofwater, and dilute to 100 mL.12.7 Potassium Cyanide Solution (50 g/L)Dissolve2gofpotassium hydroxide (KOH) in water, add5gofpotassiumcyanide (KCN) (Warning; see 12.7.1 ), dilute to 100 mL, andtransfer to a plastic bottle.12.7.1 Warning: The preparation, storage, and use of KCNr
24、equire care and attention. Avoid inhalation of fumes andexposure of the skin to the chemical and its solutions. Work ina well-ventilated hood. Refer to Section 7 of Practices E50.12.8 Potassium Hydroxide Buffer Solution (pH 12.5)Dissolve 531 g of KOH in water, add 50 g of KCN (Warning;see 12.7.1 ),
25、and dilute to 1 L. Store the solution in a plasticcontainer.12.9 Triethanolamine Solution (200 mL/L)Dilute 20 mLof triethanolamine to 100 mL with water.13. Procedure13.1 Transfer a 1.0-g sample, weighed to the nearest 0.1 mg,to a dry 500-mL TFE-fluorocarbon beaker. Add 10 mL ofHNO3. Cautiously add 1
26、0 mL of HF, and heat gently until thesample is dissolved. Wash the sides of the beaker with a finestream of water.Add 20 mLof HClO4, place on a hot plate witha surface temperature not exceeding 300C, and evaporate todense fumes of HClO4. Cool, add 10 mL of HCl (1+1), andheat to dissolve salts. Trans
27、fer to a 600-mL glass beaker andevaporate to moderate dryness on a hot plate. Place on a burnerand evaporate to complete dryness (indicated by the absence offumes). Add 20 mL of HCl (1+1), wash the sides of the beakerwith a fine stream of water, and heat to dissolve salts.13.2 Add 200 mL of water an
28、d5gofNH4Cl. Heat toboiling. Remove from the hot plate and cool.Add NH4OH untilthe iron begins to precipitate. Using a pH meter, adjust the pHto 4.25 + 0.25 by adding NH4OH dropwise. Cool to roomtemperature, transfer to a 500-mL volumetric flask, dilute tovolume, and mix. Let stand1htoallow the preci
29、pitate to settle.13.3 Dry-filter approximately 200 mL of the solutionthrough a 12.5-cm medium filter paper into a dry beaker. Usinga pipet, transfer 50 mL of the solution to a 250-mL beaker.13.4 Titration of CalciumAdd 5 mL of triethanolaminesolution, stir, and immediately add 5 mL of the KOH buffer
30、solution (Warning; see 12.7.1 ). Add 100 mg of hydroxyE 372 01 (2006)2naphthol blue indicator mixture. Titrate with EDTA solution(0.005 M) to the disappearance of the last trace of the red color.13.5 Titration of Calcium and MagnesiumUsing a pipet,transfer a second aliquot portion of the filtered so
31、lution from13.3 to a 250-mL beaker in accordance with the following:Magnesium, %SampleWeight, gAliquot forMagnesiumDetermination, mL2.0to5.0 1.0 505.0 to 12.0 1.0 2513.6 Add 5 mL of triethanolamine solution, stir, and imme-diately add 10 mL of the NH4Cl buffer solution. Add 5 mL ofthe KCN solution (
32、Warning; see 12.7.1 ), and 3 to 5 drops ofEriochrome Black-T solution. Titrate with the EDTA solution(0.005 M) to the disappearance of the last trace of the red color.NOTE 2In going through the end point, the color changes from red toblue to blue-green. The appearance of a blue-green color indicates
33、over-titration.14. Calculation14.1 Calculate the percentage of calcium as follows:Calcium, % 5 A 3 B!/C 3 100 (3)where:A = EDTA solution required to titrate the calcium (13.4),mLB = calcium equivalent of the EDTA solution, mg/mL(12.3.2), andC = sample represented in the final aliquot, mg.14.2 Calcul
34、ate the percentage of magnesium as follows:Magnesium, % 5D 2 A/E!# 3 FG3 100 (4)where:A = EDTA solution required to titrate the calcium (13.4),mL,D = EDTA solution required to titrate the magnesium andcalcium (13.6), mL,E = 50 divided by millilitres of aliquot taken for titrationof magnesium and cal
35、cium (13.5),F = magnesium equivalent of the EDTA solution, mg/mL(12.3.3), andG = sample represented in the final aliquot, mg.15. Precision and Bias15.1 PrecisionEight laboratories cooperated in testingthis method and obtained the data summarized in Table 1 andTable 2. Samples with calcium and magnes
36、ium concentrationsnear the upper limit of the scope were not available for testing.15.2 BiasThe bias of this method could not be evaluatedbecause adequate certified standard reference materials wereunavailable at the time of testing. The user is cautioned toverify by the use of certified reference m
37、aterials, if available,that the accuracy of this method is adequate for the contem-plated use.16. Keywords16.1 chemical analysis; ferrosilicon; magnesium ferrosili-con; titrimetric methodASTM International takes no position respecting the validity of any patent rights asserted in connection with any
38、 item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical
39、committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at
40、 a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor D
41、rive, 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
42、.org).TABLE 1 Statistical InformationCalciumTest SpecimenCalciumFound, %Repeatability(R1, E 173)Reproducibility(R2, E 173)1. 48Si-45Fe 0.496 0.035 0.0442. 46Si-43Fe 1.06 0.04 0.08TABLE 2 Statistical InformationMagnesiumTest SpecimenMagnesiumFound, %Repeatability(R1, E 173)Reproducibility(R2, E 173)1. 48Si-45Fe 5.16 0.13 0.152. 46Si-43Fe 8.98 0.18 0.30E 372 01 (2006)3
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