1、Designation: E878 11Standard Test Method forDetermination of Titanium in Iron Ores and RelatedMaterials by Diantipyrylmethane Ultraviolet Spectrometry1This standard is issued under the fixed designation E878; the number immediately following the designation indicates the year oforiginal adoption or,
2、 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.1. Scope1.1 This test method covers the determination of titanium iniron ores, concentrates,
3、 and agglomerates in the compositionalrange from 0.01 % to 6.0 % titanium.NOTE 1As used in this test method (except as related to the termrelative standard deviation), percent or “%” refers to mass fraction(wt/wt) of the form g/100g.1.2 The values stated in SI units are to be regarded asstandard. No
4、 other units of measurement are included in thisstandard.1.3 This test method has been evaluated in accordance withPractice E1601 and Guide E1763. Unless otherwise noted in13, the lower limit in the scope of each method specifies thelowest analyte content that may be analyzed with acceptableerror (d
5、efined as a nominal 5 % risk of obtaining a 50 % orlarger relative difference in results on the same test sample intwo laboratories).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 to estab
6、lish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D1193 Specification for Reagent WaterE50 Practices for Apparatus, Reagents, and Safety Consid-erations for Chemical Analysis of Metals, Ore
7、s, andRelated MaterialsE135 Terminology Relating to Analytical Chemistry forMetals, Ores, and Related MaterialsE877 Practice for Sampling and Sample Preparation of IronOres and Related Materials for Determination of ChemicalCompositionE882 Guide for Accountability and Quality Control in theChemical
8、Analysis LaboratoryE1601 Practice for Conducting an Interlaboratory Study toEvaluate the Performance of an Analytical MethodE1763 Guide for Interpretation and Use of Results fromInterlaboratory Testing of Chemical Analysis Methods3. Terminology3.1 For definitions of terms used in this test method, r
9、efer toTerminology E135.4. Summary of Test Method4.1 The sample is decomposed by treatment with hydro-chloric, nitric, and sulfuric acids, or by sintering with sodiumperoxide, or by fusion with sodium tetraborate and sodiumcarbonate. Iron is reduced in an acid medium with ascorbicacid, the color is
10、developed with diantipyrylmethane, and theabsorbance is measured at approximately 385 nm.5. Significance and Use5.1 This test method is intended to be used for compliancewith compositional specifications for titanium content. It isassumed that all who use these procedures will be trainedanalysts cap
11、able of performing common laboratory proceduresskillfully and safely. It is expected that work will be performedin a properly equipped laboratory and that proper wastedisposal procedures will be followed. Appropriate qualitycontrol practices must be followed such as those described inGuide E882.6. I
12、nterferences6.1 None of the elements normally found in iron oresinterfere.7. Reagents and Materials7.1 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unless otherwise indicated, it is intended thatall reagents conform to the specifications of the Committee on1This test method i
13、s 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 Dec. 15, 2011. Published January 2012. Originallya
14、pproved in 1982. Last previous edition approved in 2005 as E878 01 (2005).DOI: 10.1520/E0878-11.2For 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 Docume
15、nt Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.Analytical Reagents of the American Chemical Society wheresuch specifications are available.3Other grades may be used,provided it is first ascertained
16、 that the reagent is of sufficienthigh purity to permit its use without lessening the accuracy ofthe determination.7.2 Purity of WaterUnless otherwise indicated, referencesto water shall be understood to mean reagent water conformingto Type I or II of Specification D1193. Type III or IV may beused i
17、f they effect no measurable change in the blank orsample.7.3 Ascorbic Acid Solution (10 g/100 mL) (C6H8O6)Dissolve 10 g of ascorbic acid (C6H8O6) in water and dilute to100 mL. Prepare fresh as needed.7.4 Diantipyrylmethane Solution (15 g/L) C23H24O2N4H2ODissolve 15 g of the reagent in about 300 mL o
18、f waterand 30 mL of (H2SO4) (1 + 1) and dilute to 1 L with water. Ifa residue remains, filter and store the filtrate in a brown bottle.7.5 Ferric Ammonium Sulfate (100 g/L)Dissolve 100 g offerric ammonium sulfate Fe2(SO4)3(NH4)2SO4in 800 mL ofwater containing 5 mL of H2SO4(1 + 1) and dilute to 1 L w
19、ithwater.7.6 Potassium Pyrosulfate (K2S2O7).7.7 Sodium Tetraborate (Anhydrous) (Na2B4O7)Dry thecommercial sodium tetraborate at 60 C to 70 C, then at 160C, and finally calcine at 400 C.7.8 Sodium Tetraborate/Sodium Carbonate (Na2B4O7/Na2CO3) Fusion Mixture Mix 1 part of Na2B4O7and 1 partof Na2CO3and
20、 store in an airtight container.7.9 Standard Titanium Solution:7.9.1 Solution A (1 mL = 0.1 mg Ti)Transfer 0.1670 g ofTiO2(previously calcined at 900 C) to a platinum crucible,add3gto4gofK2S2O7, cover, and fuse at a temperature of600 C until a clear melt is obtained. Place the cooled crucibleand cov
21、er into a 250-mLbeaker, add 50 mLto 60 mLof H2SO4(1 + 9), and heat to dissolve the melt. Wash crucible and coverwith H2SO4(1 + 9) and remove, adding the washings to the250-mL beaker. Transfer the solution of a 1-L volumetric flask,dilute to volume with H2SO4(1 + 9), and mix.7.9.2 Solution B (1 mL =
22、0.02 mg Ti)Transfer 50.0 mL ofstandard titanium Solution A to a 250-mL volumetric flask,dilute to volume with H2SO4(1 + 9), and mix.8. Hazards8.1 For precautions to be observed in this test method, referto Practices E50.9. Sampling and Sample Preparation9.1 SamplingThe gross sample shall be collecte
23、d andprepared in accordance with Practice E877.9.2 Sample PreparationPulverize the laboratory sampleto pass a No. 100 (150-m) sieve.NOTE 2To facilitate decomposition, some ores such as specularhematite require grinding to pass a No. 200 (75-m) sieve.10.4.10. ProcedureNOTE 3If the procedure is based
24、on acid decomposition, use steps in10.1. If the procedure is based on alkaline sintering, use steps in 10.2.Ifthe procedure is based on alkaline fusion, use steps in 10.3.10.1 Acid Decomposition:10.1.1 Weigh approximately the amount of the test samplespecified in the table below into a small weighin
25、g bottlepreviously dried at 150 C.Ti content, %Mass of testportion, gAmount ofH2SO4to be addedin 10.1.3,mLAliquot,mL0.010.1 1.0 20 200.10.3 1.0 20 100.31.0 0.5 10 51.06.0 0.1 10 5Dry the bottle and contents for1hat105Cto110C.Capthe bottle and cool to room temperature in a desiccator.Momentarily rele
26、ase the cap to equalize the pressure and weighthe capped bottle and sample to the nearest 0.1 mg. Repeat thedrying and weighing until there is no further loss of mass.Transfer the test sample to a 250-mL beaker and reweigh thecapped bottle to the nearest 0.1 mg. The difference between thetwo masses
27、is the mass of the test sample taken for analysis.10.1.2 Carry a reagent blank through all steps of theprocedure, starting with 10.1.3.10.1.3 Decomposition of SampleMoisten the test samplewith a few milliliters of water, add 30 mL of HCl, cover, anddigest below the boiling point until no further att
28、ack isapparent. Add 5 mL of HNO3and 10 mL to 20 mL ofH2SO4(see amounts specified in 10.1.1) evaporate slowly tofumes of H2SO4, then heat strongly for 10 min. Allow thesolution to cool, add slowly 50 mL of water and 20 mL of HCl,and warm until soluble salts are in solution.10.1.4 Filter on a fine-tex
29、tured filter paper and collect thefiltrate in a 250-mL beaker. Transfer the residue quantitativelyto the filter paper and wash the filter paper two or three timeswith hot dilute H2SO4(2 + 98) and two or three times with hotwater. Reserve the filtrate.10.1.5 Treatment of Insoluble Matter Ignite the p
30、aper andresidue in a platinum crucible. Cool, moisten with severaldrops of water, add 3 or 4 drops of dilute H2SO4(1 + 1) and 10mL of HF. Evaporate slowly to expel silica and excess ofH2SO4. Cool, add to the residue about2gofpotassiumpyrosulfate, cover the crucible, and fuse over a burner (ap-proxim
31、ately 500 C) until a clear melt is obtained.10.1.6 Dissolve the cool melt in the reserved filtrate from10.1.4, remove, and wash the crucible and cover, adding thewashings to the 250-mL beaker. Transfer the solution to a200-mL volumetric flask, dilute to volume, and mix. Continuein accordance with 10
32、.4.10.2 Alkaline Sintering Decomposition:10.2.1 Transfer a sample weight in accordance with thetable in 10.1.1 to a dried weighing bottle and dry the testsample as described in 10.1.1. Finally transfer the test sampleto a 40-mL nickel crucible.3Reagent Chemicals, American Chemical Society Specificat
33、ions , AmericanChemical Society, Washington, DC. For suggestions on the testing of reagents notlisted by the American Chemical Society, see the United States Pharmacopeia andNational Formulary, U.S. Pharmaceutical Convention, Inc. (USPC), Rockville,MD.E878 11210.2.2 Carry a reagent blank through all
34、 steps of theprocedure starting with 10.2.3.10.2.3 Add3gofsodium peroxide and mix using aplatinum or nickel spatula. Place the crucible for severalminutes at the entrance of a muffle furnace set at 400 C, thenplace the crucible inside the furnace for about 1 h, for sintering.Remove the crucible and
35、allow to cool.10.2.4 Transfer the sintered mass to a 250-mLbeaker, cover,and add about 75 mL of water. Wash the crucible once withwater and once with dilute HCl (1 + 4), adding the washings tothe beaker. Acidify carefully with 30 mL of concentrated HCl,cover the beaker, and heat gently until a clear
36、 solution isobtained. Add 20 mL of dilute H2SO4(1 + 1) and evaporateslowly to fumes of H2SO4; then heat strongly for 10 min.Allow the solution to cool, add slowly 50 mL of water and 20mL of concentrated HCl, and warm until soluble salts are insolution.10.2.5 Continue as described in 10.1.4-10.1.6. F
37、inally carryout spectrophotometric measurements as described in 10.4.10.3 Alkaline Fusion Decomposition:10.3.1 Transfer a test sample weight in accordance with thetable in 10.1.1 to a dried weighing bottle and dry the sampleportion as described in 10.1.1. Finally transfer the sample to aplatinum cru
38、cible.10.3.2 Carry a reagent blank through all steps of theprocedure starting with 10.3.3.10.3.3 Add5goffusion mixture (7.8) and mix, using aplatinum or nickel spatula. Cover the crucible and heat in amuffle furnace, first gently at 600 C and finally for 10 min at1000 C to 1050 C. Remove the crucibl
39、e and swirl cautiouslyto cause the cooling melt to solidify in a thin layer on the wallsof the crucible.10.3.4 Place the cooled crucible and cover into a 250-mLbeaker and add 100 mL of dilute HCl (1 + 4). Heat gently todissolve the melt, remove, and wash the crucible, cover, andpolice adding the was
40、hing to the 250-mL beaker.10.3.5 Transfer the solution to a 200-mL volumetric flask,dilute to volume, and mix. Continue in accordance with 10.4.10.4 Preparation of Test Solution for SpectrophotometricMeasurementsTransfer with the help of pipet, an aliquot ofthe test solution and the blank solution i
41、n accordance with thetable in 10.1 and transfer into 100-mL volumetric flasks. Add5 mL of ferric ammonium sulfate solution (7.5), and 10 mL ofascorbic acid solution (7.3), and mix. Add 15 mL of dilute HCl(1 + 1) and 30 mL of diantipyrylmethane solution (7.4), diluteto volume, and mix. Allow the solu
42、tion to stand for at least 10min.10.5 Preparation of Calibration Solutions for Spectropho-tometric MeasurementsTransfer with the help of a pipet (0.0,1.0, 3.0, 5.0, 7.0), and 10.0 mL of the titanium standardSolution B (7.9.2) to six 100-mL volumetric flasks, add 5 mLof ferric ammonium sulfate soluti
43、on (7.5) and 10 mL ofascorbic acid solution (7.3), and mix. Add 15 mL of dilute HCl(1 + 1) and 30 mL of diantipyrylmethane solution (7.4), diluteto volume, and mix. Allow the solution to stand for at least 10min.11. Photometry11.1 Adjust the spectrophotometer to the initial setting,using water as th
44、e reference solution. While maintaining thissetting, take spectrophotometric readings of the blank, stan-dard, and test solutions, using a light band centered atapproximately 385 nm in a 1-cm cell (see Note 2).11.2 Preparation of Calibration Curve Subtract the aver-age absorbance of the 0-mL titaniu
45、m standard solution fromthe average absorbance of each standard solution and plot thenet absorbance against milligrams of titanium per 100 mL ofsolution.TABLE 1 Grand Means and Precision of Titanium Content of the Test Samples as Determined by the Method Described Using VariousDecomposition MethodsS
46、ampleNo.DecompositionMethodsGrand MeanX,%Repeatabilityr, %PermissibleToleranceP, %Standard DeviationWithin-Laboratoriessr,%Between-LaboratoriessL,%76-3 Acid 3.7944 0.0788 0.1706 0.0285 0.058276-3 Sintering 3.8137 0.0848 0.2765 0.0306 0.097476-3 Fusion 3.8122 0.0785 0.1995 0.0283 0.069276-16 Acid 0.0
47、399 0.0023 0.0042 0.0008 0.001476-16 Sintering 0.0402 0.0026 0.0051 0.0009 0.001776-16 Fusion 0.0402 0.0015 0.0034 0.0005 0.001276-17 Acid 0.1602 0.0032 0.0102 0.0012 0.003676-17 Sintering 0.1625 0.0049 0.0133 0.0018 0.004676-17 Fusion 0.1608 0.0055 0.0129 0.0020 0.004476-18 Acid 0.1796 0.0049 0.008
48、1 0.0018 0.002776-18 Sintering . . . . .76-18 Fusion 0.1856 0.0090 0.0159 0.0032 0.0053TABLE 2 Regression Equations of the Precisions as Functions of Titanium Content in the Samples for Various Methods ofDecomposition(a) Acid Attack (b) Sintering (c) Fusionr = 0.0202 3 + 0.0035 r = 0.0219 3 + 0.0015
49、 r = 0.0197 3 + 0.0040P = 0.0438 3 + 0.0068 P = 0.0725 3 0.0017 P = 0.0508 3 + 0.0074sr= 0.0072 3 + 0.0016 sr= 0.0079 3 + 0.0005 sr= 0.0071 3 + 0.0014sL= 0.0150 3 + 0.0022 sL= 0.0256 3 0.0008 sL= 0.0176 3 + 0.0025E878 11311.3 Photometric RangeThe recommended concentrationrange is from 0.03 mg to 0.2 mg in 100 mL using a cell depthof 1 cm.NOTE 4Cells having other dimensions may be used, provided suitableadjustments can be made in the amount of sample and reagent used.12. Calculation12.1 Subtract the average absorbance of the reagent bl
