ASTM E507-2008 133 Standard Test Method for Analysis of Aluminum in Iron Ores by Flame Atomic Absorption Spectrometry.pdf

1、Designation: E 507 08Standard Test Method forAnalysis of Aluminum in Iron Ores by Flame AtomicAbsorption Spectrometry1This standard is issued under the fixed designation E 507; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the ye

2、ar 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.1. Scope1.1 This test method covers the determination of aluminumin iron ores, concentrates, and agglomerates in the massfra

3、ction (%) range from 0.1 to 5.1.2 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of t

4、his 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 1193 Specification for Reagent WaterE50 Practices for Apparatus, Reagents, and Safety Consid-erations for Chemical A

5、nalysis of Metals, Ores, andRelated MaterialsE 135 Terminology Relating to Analytical Chemistry forMetals, Ores, and Related MaterialsE 276 Test Method for Particle Size or Screen Analysis atNo. 4 (4.75-mm) Sieve and Finer for Metal-Bearing Oresand Related MaterialsE 663 Practice for Flame Atomic Ab

6、sorption Analysis3E 882 Guide for Accountability and Quality Control in theChemical Analysis Laboratory3. Terminology3.1 DefinitionsFor definitions of terms used in this testmethod, refer to Terminology E 135.4. Summary of Test Method4.1 The sample is dissolved in HCl with the addition of asmall amo

7、unt of HNO3. After evaporation and dehydration,any insoluble residue is filtered, treated for the recovery ofaluminum, and added to the main solution. The solution isaspirated into the flame of a nitrous oxide-acetylene burner.The absorbed energy at the resonance line of the spectrum ofaluminum is m

8、easured by atomic absorption spectrometry andcompared with that of the calibration solutions.5. Significance and Use5.1 This test method is intended as a referee method forcompliance with compositional specifications for impuritycontent. It is assumed that all who use this procedure will betrained a

9、nalysts capable of performing common laboratorypractices skillfully and safely. It is expected that work will beperformed in a properly equipped laboratory and that properwaste disposal procedures will be followed. Follow appropriatequality control practices such as those described in GuideE 882.6.

10、Interferences6.1 None of the elements normally found in iron oresinterfere with this test method.7. Apparatus7.1 Atomic Absorption Spectrophotometer, meeting the fol-lowing criteria:7.1.1 Minimum SensitivityThe absorbance of the highestcalibration solution (see 8.4) must be at least 0.3.7.1.2 Curve-

11、LinearityThe difference between the read-ings of the two highest calibration solutions must be more than1.4 times the difference between the readings for the zerosolution and the lowest calibration solution.7.1.3 Minimum StabilityThe coefficient of variation of anumber of measurements of the highest

12、 calibration solutionand of the zero calibration solution must be less than 1.5 % and0.5 %, respectively.NOTE 1Use of digital readout devices or printers, or both, is advis-able.NOTE 2Instrument parameters will vary with each instrument. Thefollowing parameters were successfully used in several labo

13、ratories and1This test method is under the jurisdiction of ASTM Committee E01 onAnalytical Chemistry for Metals, Ores, and Related Materials and is the directresponsibility of Subcommittee E01.02 on Ores, Concentrates, and Related Metal-lurgical Materials.Current edition approved Nov. 1, 2008. Publi

14、shed December 2008. Originallyapproved in 1973. Last previous edition approved in 2003 as E 507 03.2For referenced 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 Doc

15、ument Summary page onthe ASTM website.3Withdrawn. The last approved version of this historical standard is referencedon www.astm.org.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.they can be used as guidelines. Solutions were aspir

16、ated into a nitrousoxide-acetylene flame of a premix burner.Hollow cathode lamp, mA 25Wavelength, nm 396.15Nitrous oxide flow rate, L/min 13.8Acetylene flow rate, L/min 6.68. Reagents and Materials8.1 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unless otherwise indicated, it

17、 is intended thatall reagents conform to the specifications of the Committee onAnalytical Reagents of the American Chemical Society wheresuch specifications are available.4Other grades may be used,provided it is first ascertained that the reagent is of sufficientlyhigh purity to permit its use witho

18、ut lessening the accuracy ofthe determination.8.2 Purity of WaterUnless otherwise indicated, referencesto water shall be understood to mean reagent water as definedby Type I of Specification D 1193.8.3 Aluminum, Standard Solution (1 mL = 0.5 mg Al)Dissolve 0.5000 g of high-purity aluminum in 25 mL o

19、f HCland dilute to 1 L.8.4 Aluminum Calibration SolutionsTransfer (5.0, 10.0,20.0, 40.0, and 50.0)-mL portions of the standard aluminumsolution to 200-mL volumetric flasks. Dilute to about 100 mL,add 6 mL of HCl and 60 mL of the background solution, diluteto volume, and mix. These calibration soluti

20、ons contain (12.5,25, 50, 100, and 125) g/mL Al, respectively.8.5 Iron, Background Solution (10 g/L)Dissolve 10 g ofhigh-purity iron in 50 mL of HCl and oxidize by the dropwiseaddition of HNO3. Evaporate to a syrupy consistency. Add 20mL of HCl and dilute to 200 mL with water. Add 20 g of NaCldissol

21、ved in 200 mL water and dilute to 1 L with water.8.6 Zero Calibration SolutionTransfer 60 mL of thebackground solution to a 200-mLvolumetric flask, add 6 mLofHCl, dilute to volume, and mix.9. Hazards9.1 For precautions to be observed in this method, refer toPractice E50.10. Sample Preparation10.1 Th

22、e analytical sample shall be pulverized to pass a150-m sieve (see Test Method E 276).NOTE 3To facilitate decomposition, some ores, such as specularhematite, require grinding to pass a 75-m sieve.11. Procedure11.1 Transfer approximately 1.0 g of the sample to a smallweighing bottle previously dried a

23、t about 150 C. Dry thebottle and contents for1hat105Cto110C.Capthebottleand cool to room temperature in a desiccator. Momentarilyrelease the cap to equalize the pressure and weigh the cappedbottle and sample to the nearest 0.1 mg. Repeat the drying andweighing until there is no further weight loss.

24、Transfer thesample to a 250-mL beaker and reweigh the capped bottle tothe nearest 0.1 mg. The difference between the two weights isthe weight of the sample taken for analysis.11.2 Carry a reagent blank through all steps of the procedurestarting with 11.3.11.3 Decomposition of SampleMoisten the sampl

25、e with afew millilitres of water, add 25 mL of HCl, cover and digestbelow the boiling point until no further attack is apparent. Add2mLofHNO3and digest for several minutes. Remove thecover and evaporate the solution to dryness. Heat the salts ona hot plate at 105 C to 110 C for 15 min. Add 5 mL of H

26、Cl,cover the beaker, and warm for several min. Add 50 mL ofwater and warm until soluble salts are in solution. Filter on afine-textured paper, and collect the filtrate in a 250-mL beaker.Transfer the residue quantitatively to the filter paper. Washalternatively with hot dilute HCl (1 + 9) and hot wa

27、ter until theyellow color of ferric chloride is no longer apparent and thenwith hot water six to eight times. Transfer the paper and residueto a platinum crucible. Reserve the filtrate.11.4 Treatment of ResidueIgnite the paper and residue inthe platinum crucible. Cool, moisten with several drops ofw

28、ater, and add three or four drops of H2SO4(1 + 1) and 10 mLof HF. Evaporate slowly to expel silica and then fume off theexcess of H2SO4. Ignite to about 700 C.Add1gofanhydrousNa2CO3to the residue, cover the crucible, and fuse over aburner or in a muffle furnace until a clear melt is obtained.Dissolv

29、e the cool melt in the reserved filtrate from 11.3,remove and wash the crucible and cover. Transfer the solutionto a 200-mL volumetric flask, dilute to volume, and mix. If thesolution is cloudy at this stage, indicating the presence oftitania, filter a portion of the solution through a dry paper int

30、oa dry beaker. Use this solution for the atomic absorptionmeasurements, if the aluminum content is between 0.1 % and2.5 %. For aluminum contents greater than 2.5 %, transfer a40-mL aliquot to a 200-mL volumetric flask and add 50 mL ofbackground solution and 4 mL of HCl. Dilute to volume andmix.11.5

31、Adjustment of Atomic AbsorptionSpectrophotometerIn accordance with Practice E 663, set theinitial instrument parameters to the values in Note 2. Light theburner and aspirate water until the instrument comes to thermalequilibrium. Optimize instrument response by adjusting thewavelength, fuel, air, bu

32、rner, and nebulizer while aspirating thehighest calibration solution to obtain maximum absorption orabsorbance.Aspirate water until a steady signal is obtained andadjust the instrument readout system to obtain zero absorptionor absorbance.NOTE 4The manufacturers instructions for igniting and extingu

33、ish-ing the nitrous oxide-acetylene burner should be strictly followed to avoidpossible explosion hazards. Tinted safety glasses should be worn by theoperator whenever the flame is burning.11.6 MeasurementsAspirate water until the initial readingis again obtained.Aspirate the calibration solutions i

34、n the orderof increasing absorption or absorbance starting with the zerocalibration solution. When a stable response is obtained foreach solution, record the readings.Aspirate the test solutions at4Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC,

35、 http:/www.chemistry.org. For suggestions onthe testing of reagents not listed by the American Chemical Society, see AnnualStandards for Laboratory Chemicals, BDH Ltd., Poole, Dorset, U.K., http:/, and the United States Pharmacopeia and National Formulary, U.S.Pharmacopeial Convention, Inc. (USPC),

36、Rockville, MD, http:/www.usp.org.E507082the proper points in the calibration series. Aspirate waterbetween each calibration and test solution. Repeat all measure-ments at least two more times.12. Calculation12.1 If necessary, convert the average of the readings foreach calibration solution to absorb

37、ance. Obtain the net absor-bance of each calibration solution by subtracting the averageabsorbance of the zero calibration solution. In a similarmanner, obtain the net absorbance of the test solution bysubtracting the absorbance of the reagent blank solution.12.2 Prepare a calibration curve by plott

38、ing the net absor-bance values of the calibration solutions against micrograms ofaluminum per milliliter.12.3 Convert the net absorbance values of the samplesolution to micrograms of aluminum per milliliter, by means ofthe calibration curve.12.4 Calculate the mass fraction (%) of aluminum as fol-low

39、s:Aluminum, % 5 A 3 200!/B 3 10 000! (1)where:A = aluminum, g/mL, andB = sample represented in the 200-mL volume of the finaltest solution, g.13. Precision and Bias13.1 PrecisionTable 1 indicates the precision of themethod within and between laboratories when applied to anumber of samples of iron or

40、es.13.2 BiasNo information on the accuracy of this testmethod is known. The accuracy of this test method may bejudged by comparison of accepted values for standard refer-ence materials, with the mean determined through interlabora-tory testing.14. Keywords14.1 aluminum; atomic absorption spectrometr

41、y; iron oresASTM International takes no position respecting the validity of any patent rights asserted in connection with any 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

42、 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 withdrawn. Your comments are invited either for revision of this standard or for additi

43、onal standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at 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

44、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 a

45、boveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).TABLE 1 Precision of Method Within and Between LaboratoriesAverage Mass Fraction(%)Aof AlRelative Standard DeviationBWithin Laboratories, %Relative StandardDeviationBBet

46、weenLaboratories, %Number of LaboratoriesNumber ofDeterminations0.178 4.49 7.87 30 880.261 4.21 18.77 31 910.426 2.58 5.40 11 310.667 1.35 2.40 7 190.884 1.81 6.11 24 721.46 2.53 2.47 29 852.14 2.01 5.14 31 91AEach mass fraction (%) of aluminum represents a different kind of iron ore.BRelative standard deviation (RSD), in this test method is calculated as follows:RSD 5 100/ X! =(d2!/n 2 1!where:X= average mass fraction (%),d = difference of the determination from the mean, andn = number of determinations.E507083