1、Designation: E507 09E507 13Standard Test Method forDetermination of Aluminum in Iron Ores by Flame AtomicAbsorption Spectrometry1This standard is issued under the fixed designation E507; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revisi
2、on, 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.1. Scope1.1 This test method covers the determination of aluminum in iron ores, concentrates, and agglomerates in
3、the mass fraction(%) range from 0.1 to 5.1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof
4、 the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D1193 Specification for Reagent WaterE50 Practices forApparatus, Reagents, and Safety Considerations for Ch
5、emicalAnalysis of Metals, Ores, and Related MaterialsE135 Terminology Relating to Analytical Chemistry for Metals, Ores, and Related MaterialsE276 Test Method for Particle Size or ScreenAnalysis at No. 4 (4.75-mm) Sieve and Finer for Metal-Bearing Ores and RelatedMaterialsE663 Practice for Flame Ato
6、mic Absorption Analysis (Withdrawn 1997)3E882 Guide for Accountability and Quality Control in the Chemical Analysis Laboratory3. Terminology3.1 DefinitionsFor definitions of terms used in this test method, refer to Terminology E135.4. Summary of Test Method4.1 The sample is dissolved in HCl with the
7、 addition of a small amount of HNO3. After evaporation and dehydration, anyinsoluble residue is filtered, treated for the recovery of aluminum, and added to the main solution. The solution is aspirated intothe flame of a nitrous oxide-acetylene burner. The absorbed energy at the resonance line of th
8、e spectrum of aluminum is measuredby atomic absorption spectrometry and compared with that of the calibration solutions.5. Significance and Use5.1 This test method is intended as a referee method for compliance with compositional specifications for impurity content. Itis assumed that all who use thi
9、s procedure will be trained analysts capable of performing common laboratory practices skillfullyand safely. It is expected that work will be performed in a properly equipped laboratory and that proper waste disposal procedureswill be followed. Follow appropriate quality control practices such as th
10、ose described in Guide E882.6. Interferences6.1 None of the elements normally found in iron ores interfere with this test method.1 This test method is under the jurisdiction of ASTM Committee E01 on Analytical Chemistry for Metals, Ores, and Related Materials and is the direct responsibility ofSubco
11、mmittee E01.02 on Ores, Concentrates, and Related Metallurgical Materials.Current edition approved Oct. 1, 2009Oct. 1, 2013. Published April 2010November 2013. Originally approved in 1973. Last previous edition approved in 20082009 asE507 08.E507 09. DOI: 10.1520/E0507-09.10.1520/E0507-13.2 For refe
12、rencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.3 The last approved version of this historical standard is referenced o
13、n www.astm.org.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users co
14、nsult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States17. Apparatus7.1 Atomic Absorption
15、 Spectrometer, meeting the following criteria:7.1.1 Minimum SensitivityThe absorbance of the highest calibration solution (see 8.4) must be at least 0.3.7.1.2 Curve-LinearityThe difference between the readings of the two highest calibration solutions must be more than 1.4 timesthe difference between
16、 the readings for the zero solution and the lowest calibration solution.7.1.3 Minimum StabilityThe coefficient of variation of a number of measurements of the highest calibration solution and ofthe zero calibration solution must be less than 1.5 % and 0.5 %, respectively.NOTE 1Use of digital readout
17、 devices or printers, or both, is advisable.NOTE 2Instrument parameters will vary with each instrument. The following parameters were successfully used in several laboratories and they canbe used as guidelines. Solutions were aspirated into a nitrous oxide-acetylene flame of a premix burner.Hollow c
18、athode 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 be used in all tests. Unless otherwise indicated, it is intended that allreagents conform to the specifications of the
19、Committee on Analytical Reagents of the American Chemical Society where suchspecifications are available.4 Other grades may be used, provided it is first ascertained that the reagent is of sufficiently high purityto permit its use without lessening the accuracy of the determination.8.2 Purity of Wat
20、erUnless otherwise indicated, references to water shall be understood to mean reagent water as defined byType I of Specification D1193.8.3 Aluminum, Standard Solution (1 mL = 0.5 mg Al)Dissolve 0.5000 g of high-purity aluminum in 25 mL of HCl, cool,transfer to a 1-L volumetric flask, dilute to volum
21、e, and mix.8.4 Aluminum Calibration SolutionsTransfer (5.0, 10.0, 20.0, 40.0, and 50.0)-mL portions of the standard aluminum solutionto 200-mL volumetric flasks. Dilute to about 100 mL, add 6 mL of HCl and 60 mL of the background solution, dilute to volume,and mix. These calibration solutions contai
22、n (12.5, 25, 50, 100, and 125) g/mL Al, respectively.8.5 Iron, Background Solution (10 g/L)Dissolve 10 g of high-purity iron in 50 mL of HCl and oxidize by the dropwiseaddition of HNO3. Evaporate to a syrupy consistency. Add 20 mL of HCl and dilute to 200 mL with water. Add 20 g of NaCldissolved in
23、200 mL water and dilute to 1 L with water.8.6 Zero Calibration SolutionTransfer 60 mL of the background solution to a 200-mL volumetric flask, add 6 mL of HCl,dilute to volume, and mix.9. Hazards9.1 For precautions to be observed in this method, refer to Practice E50.10. Sample Preparation10.1 The a
24、nalytical sample shall be pulverized to pass a 150-m sieve (see Test Method E276).NOTE 3To facilitate decomposition, some ores, such as specular hematite, require grinding to pass a 75-m sieve.11. Procedure11.1 Transfer approximately 1.0 g of the sample to a small weighing bottle previously dried at
25、 about 150 C. Dry the bottle andcontents for 1 h at 105 C to 110 C. Cap the bottle and cool to room temperature in a desiccator. Momentarily release the cap toequalize the pressure and weigh the capped bottle and sample to the nearest 0.1 mg. Repeat the drying and weighing until thereis no further w
26、eight loss. loss of mass. Transfer the sample to a 250-mL beaker and reweigh the capped bottle to the nearest 0.1mg. The difference between the two weightsmasses is the weightmass of the sample taken for analysis.11.2 Carry a reagent blank through all steps of the procedure starting with 11.3.11.3 D
27、ecomposition of SampleMoisten the sample with a few millilitres of water, add 25 mL of HCl, cover and digest belowthe boiling point until no further attack is apparent. Add 2 mL of HNO3 and digest for several minutes. Remove the cover andevaporate the solution to dryness. Heat the salts on a hot pla
28、te at 105 C to 110 C for 15 min.Add 5 mL of HCl, cover the beaker,and warm for several min. Add 50 mL of water and warm until soluble salts are in solution. Filter on a fine-textured paper, andcollect the filtrate in a 250-mL beaker. Transfer the residue quantitatively to the filter paper. Wash alte
29、rnatively with hot dilute4 Reagent Chemicals, American Chemical Society Specifications, American Chemical Society, Washington, DC, www.chemistry.org. DC. For suggestions on the testingof reagents not listed by the American Chemical Society, see the United States Pharmacopeia and National Formulary,
30、U.S. Pharmacopeial Convention, Inc. (USPC),Rockville, MD, http:/www.usp.org.MD.E507 132HCl (1 + 9) and hot water until the yellow color of ferric chloride is no longer apparent and then with hot water six to eight times.Transfer the paper and residue to a platinum crucible. Reserve the filtrate.11.4
31、 Treatment of ResidueIgnite the paper and residue in the platinum crucible. Cool, moisten with several drops of water,and add three or four drops of H2SO4 (1 + 1) and 10 mL of HF. Evaporate slowly to expel silica and then fume off the excess ofH2SO4. Ignite to about 700 C. Add 1 g of anhydrous Na2CO
32、3 to the residue, cover the crucible, and fuse over a burner or in amuffle furnace until a clear melt is obtained. Dissolve the cool melt in the reserved filtrate from 11.3, remove and wash the crucibleand cover. Transfer the solution to a 200-mL volumetric flask, dilute to volume, and mix. If the s
33、olution is cloudy at this stage,indicating the presence of titania, filter a portion of the solution through a dry paper into a dry beaker. Use this solution for theatomic absorption measurements, if the aluminum content is between 0.1 % and 2.5 %. For aluminum contents greater than 2.5 %,transfer a
34、 40-mL aliquot to a 200-mL volumetric flask and add 50 mL of background solution and 4 mL of HCl. Dilute to volumeand mix.11.5 Adjustment of Atomic Absorption SpectrometerIn accordance with Practice E663, set the initial instrument parametersto the values in Note 2. Light the burner and aspirate wat
35、er until the instrument comes to thermal equilibrium. Optimize instrumentresponse by adjusting the wavelength, fuel, air, burner, and nebulizer while aspirating the highest calibration solution to obtainmaximum absorption or absorbance. Aspirate water until a steady signal is obtained and adjust the
36、 instrument readout system toobtain zero absorption or absorbance.NOTE 4The manufacturers instructions for igniting and extinguishing the nitrous oxide-acetylene burner should be strictly followed to avoid possibleexplosion hazards. Tinted safety glasses should be worn by the operator whenever the f
37、lame is burning.11.6 MeasurementsAspirate water until the initial reading is again obtained. Aspirate the calibration solutions in the order ofincreasing absorption or absorbance starting with the zero calibration solution. When a stable response is obtained for eachsolution, record the readings. As
38、pirate the test solutions at the proper points in the calibration series. Aspirate water between eachcalibration and test solution. Repeat all measurements at least two more times.12. Calculation12.1 If necessary, convert the average of the readings for each calibration solution to absorbance. Obtai
39、n the net absorbance ofeach calibration solution by subtracting the average absorbance of the zero calibration solution. In a similar manner, obtain the netabsorbance of the test solution by subtracting the absorbance of the reagent blank solution.12.2 Prepare a calibration curve by plotting the net
40、 absorbance values of the calibration solutions against micrograms ofaluminum per milliliter.12.3 Convert the net absorbance values of the sample solution to micrograms of aluminum per milliliter, by means of thecalibration curve.12.4 Calculate the mass fraction (%) of aluminum as follows:Aluminum,%
41、5A 3200!/B 310 000! (1)where:A = aluminum, g/mL, andB = sample represented in the 200-mL volume of the final test solution, g.TABLE 1 Precision of Method Within and Between LaboratoriesAverage Mass Fraction(%)A of AlRelative Standard DeviationBWithin Laboratories, %Relative StandardDeviationB Betwee
42、nLaboratories, %Number of Laboratories Number 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 91A Each mass fraction (%) of aluminum represents a different kind of iron ore.B Relative stand
43、ard deviation (RSD), in this test method is calculated as follows:RSD5s100/Xd sod 2d/sn21dwhere:X = average mass fraction (%),d = difference of the determination from the mean, andn = number of determinations.E507 13313. Precision and Bias13.1 PrecisionTable 1 indicates the precision of the method w
44、ithin and between laboratories when applied to a number ofsamples of iron ores.13.2 BiasNo information on the accuracy of this test method is known. The accuracy of this test method may be judged bycomparison of accepted values for certified reference materials, with the mean determined through inte
45、rlaboratory testing.14. Keywords14.1 aluminum; atomic absorption spectrometry; 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
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48、ts 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 Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or mu
49、ltiple 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). Permission rights to photocopy the standard may also be secured from the ASTM website (www.astm.org/COPYRIGHT/).E507 134
