1、Designation: E 248 07Standard Test Method forDetermination of Manganese in Manganese Ores byPyrophosphate Complexed Permanganate PotentiometricTitrimetry1This standard is issued under the fixed designation E 248; the number immediately following the designation indicates the year oforiginal adoption
2、 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.This standard has been approved for use by agencies of the Department of Defense.1. Sco
3、pe1.1 This definitive test method covers the determination ofmanganese in manganese ore in the range from 15 to 60 %.1.2 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 establish appro-priat
4、e 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 Analysis of Metals, Ores, andRelated M
5、aterialsE 135 Terminology Relating to Analytical Chemistry forMetals, Ores, and Related MaterialsE 691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test MethodE 882 Guide for Accountability and Quality Control in theChemical Analysis Laboratory3. Terminology3.1 Def
6、initionsFor definitions of terms used in this testmethod, refer to Terminology E 135.4. Summary of Test Method4.1 The test sample is decomposed by treatment withhydrochloric, nitric, hydrofluoric, and perchloric acids. Afterthe addition of sodium pyrophosphate and adjustment of theacidity, the manga
7、nese is determined by oxidation to trivalentmanganese with a standard solution of potassium permangan-ate. The end point is determined potentiometrically.5. Significance and Use5.1 This definitive test method is intended to be used as areferee method for compliance with compositional specifica-tions
8、 for manganese content. It is assumed that all who usethese procedures will be trained analysts capable of performingcommon laboratory procedures skillfully and safely. It isexpected that work will be performed in a properly equippedlaboratory and that proper waste disposal procedures will befollowe
9、d. Appropriate quality control practices must be fol-lowed such as those described in Guide E 882.6. Interferences6.1 Provision has been made for removal of chromium,which, under some conditions, is an interfering element.7. Apparatus7.1 pH Meter equipped with calomel and glass electrodes.7.2 Potent
10、iometric Titration Apparatus equipped withcalomel and platinum electrodes. A suitable pH meter may beused for this purpose.7.3 Magnetic StirrerUse of a TFE-fluorocarbon coveredstirring bar is recommended.8. Reagents8.1 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unless other
11、wise indicated, it is intended thatall reagents shall conform to the specifications of the Commit-tee on Analytical Reagents of the American Chemical Society,where such specifications are available.3Other grades may beused, provided it is first ascertained that the reagent is ofsufficiently high pur
12、ity to permit its use without lessening theaccuracy of the determination.1This 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-lur
13、gical Materials.Current edition approved June 1, 2007. Published June 2007. Originallyapproved in 1964. Last previous edition approved in 2002 as E 248 02.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTM
14、Standards volume information, refer to the standards Document Summary page onthe ASTM website.3“Reagent Chemicals, American Chemical Society Specifications,” Am. Chemi-cal Soc., Washington, DC. For suggestions on the testing of reagents not listed bytheAmerican Chemical Society, see “Reagent Chemica
15、ls and Standards,” by JosephRosin, D. Van Nostrand Co., Inc., New York, NY, and the “United StatesPharmacopeia.”1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.8.2 Purity of WaterUnless otherwise indicated, referencesto water shall b
16、e understood to mean reagent water conformingto Specification D 1193.8.3 Hydrochloric Acid (sp gr 1.19)Concentrated hydro-chloric acid (HCl).8.4 Hydrochloric Acid (1 + 1)Mix 1 volume of concen-trated HCl (sp gr 1.19) with 1 volume of water.8.5 Hydrofluoric Acid (48 %)Concentrated hydrofluoricacid (H
17、F).8.6 Hydrogen Peroxide (3 %)Mix 1 volume of concen-trated hydrogen peroxide (H2O2, 30 %) with 9 volumes ofwater.8.7 Nitric Acid (sp gr 1.42)Concentrated nitric acid(HNO3).8.8 Perchloric Acid (70 %) (HClO4).8.9 Potassium Permanganate, Standard Solution (0.1 N)NOTE 1The 0.1 normality of the KMnO4sol
18、ution used (3.1606 g/L)is based on the usual valence change of manganese in acid solution from7 to 2. In this test method, the manganese in the sample is oxidized fromMn(II) to Mn(III) while the KMnO4is reduced from Mn(VII) to Mn(III)The factor 0.0439 used in Section 12, therefore, is based on the f
19、ollowingcalculation: 4/5 3 0.05494 (Mn equivalent of KMnO4in 7 to 2 valencechange).8.9.1 PreparationDissolve 3.2 g of potassium permanga-nate (KMnO4) in 1 L of water. Let stand in the dark for 2weeks. Filter, without washing, through a Gooch crucible or afine porosity fritted-glass crucible. Avoid c
20、ontact with rubberor other organic material. Store in a dark-colored glass-stoppered bottle.8.9.2 StandardizationDry a portion of the National Insti-tute of Standards and Technology (NIST) standard sample, orequivalent, of sodium oxalate at 105 C. Transfer 0.3000 g ofthe sodium oxalate to a 600-mL b
21、eaker. Add 250 mL of H2SO4(5 + 95), previously boiled for 10 to 15 min and then cooled to27 C 6 3 C, and stir until the oxalate has dissolved. Add 39to 40 mL of the KMnO4solution, at a rate of 25 to 35 mL/min,while stirring slowly. Let stand until the pink color disappears(about 45 s). Heat to 55 C
22、to 60 C and complete the titrationby adding KMnO4solution until a faint pink color persists for30 s. Add the last 0.5 to 1 mL dropwise, allowing each drop tobecome decolorized before adding the next drop. To determinethe blank: Titrate 250 mL of H2SO4(5 + 95), treated as above,with KMnO4solution to
23、a faint pink color. The blank correc-tion is usually equivalent to 0.03 3 0.05 mL.8.10 Sodium Hydroxide Solution (200 g/L)Dissolve 200 gof sodium hydroxide (NaOH) in 500 to 600 mL of water anddilute to 1 L.8.11 Sodium Pyrophosphate(Na4P2O710H2O), SaturatedSolutionThis reagent shall be tested in the
24、titration of aknown amount of manganese and only lots which rapidlyprovide steady potentials shall be used.9. Hazards9.1 For precautions to be observed in this method, refer toPractice E50.10. Sample Preparation10.1 The laboratory sample shall be pulverized, if neces-sary, so that 100 % passes a No.
25、 100 (150-m) sieve.11. Procedure11.1 Transfer approximately 0.40 g (or 0.30 g if the man-ganese content exceeds 50 %) of the prepared sample to asmall weighing bottle. Place in a drying oven and dry at 120 Cfor 1 h. Cap the bottle and cool to room temperature in adesiccator. Loosen the stopper momen
26、tarily and weigh thecapped bottle and test sample to the nearest 0.1 mg. Dry the testsample for an additional 30 min. Cap the bottle, cool in adesiccator, and reweigh. Repeat the drying and weighing untilconstant weight is obtained. Transfer the sample to a 600-mLbeaker and reweigh the capped bottle
27、 to the nearest 0.1 mg.The difference between the last two weights is the weight of thesample.11.2 To the 600-mL beaker add 10 mL of concentrated HCl,10 mL of HNO3, 4 to 5 mL of HF, and 10 mL of HClO4andheat to affect solution. Evaporate to fumes of HClO4. Cool andrinse down the sides of the beaker.
28、 If complete decompositionhas not been effected, add more HCl, HNO3, and HF. Evapo-rate to fumes again and fume strongly (Note 1). Withdraw thecover slightly and volatilize any chromium present by drop-wise addition of HCl. When chromyl chloride has beenexpelled, as evidenced by the disappearance of
29、 any orangevapor upon HCl addition, replace the cover and evaporate to avolume of 2 to 3 mL or until the first appearance of saltformation on the bottom of the beaker. Cool, add 10 mL of HCl(1 + 1), and 1 mL of H2O2, and boil for 4 to 5 min.NOTE 2In rare instances there may be a small amount of blac
30、k residueat this point. If such is the case, the cool solution shall be diluted withwater and the residue filtered on a small medium-texture paper andwashed alternately with hot HCl (1 + 1) and hot water until perchloratesare removed. The paper and precipitate shall be placed in a platinumcrucible,
31、inserted into a muffle furnace, and heated to destroy thecarbonaceous matter. The residue shall then be fused with a minimumamount of sodium carbonate, cooled, and dissolved in a little water. Thesolution of this melt shall then be added to the filtrate and the solutionagain evaporated to fumes of H
32、ClO4.11.3 To the test solution add 250 to 300 mL of a coldsaturated solution of Na4P2O7. Adjust the pH to 6.5 (usingcalomel and glass electrodes on the pH meter and a magneticstirring device) with NaOH solution and HCl. The test solutionshould be clear and colorless. If a precipitate forms, dilutefu
33、rther with the Na4P2O7solution until a clear solution isobtained, maintaining a pH of 6.5. Cool from 10 C to 20 Cand titrate the manganese potentiometrically with the 0.1 NKMnO4solution. Add the titrant rapidly until the first deflec-tion of the galvanometer is noted and then dropwise to theequivale
34、nce point. The drop giving the largest potential changeshall be taken as the end point.NOTE 3If any pink coloration in the solution is evident at this point,the sample shall be discarded and the analysis repeated.12. Calculation12.1 Calculate the percentage of manganese as follows(Note 1):Manganese,
35、 % 5 4.395AB/Cwhere:E248072A = KMnO4solution required for titration of the sample,mLB = normality of the KMnO4solution, andC = sample used, g.13. Precision and Bias413.1 PrecisionSix laboratories cooperated in testing thistest method and obtained the data summarized in Table 1.13.2 BiasThe bias of t
36、his test method may be judged bycomparing accepted reference values with the correspondingarithmetic average obtained by interlaboratory testing. The hand k statistical values computed by Practice E 691 did notexceed a critical value, which would have suggested a bias inthe results of a participatin
37、g laboratory. All of the data seemconsistent, and there is no evidence that the test method gavebiased results.14. Keywords14.1 manganese content; manganese oresASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this sta
38、ndard. 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 committee and must be revi
39、ewed 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 a meeting of theresponsib
40、le 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 Drive, PO Box C700, West Co
41、nshohocken, 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.org).4Supporting data are available from ASTM International Headquarters. RequestRR:E011033.TABLE 1 Statistical InformationManganeseTitrimetric MethodTest Material Mn Found, % r, E691 R, E691Mn Ore (CMSI No. 1721, 27.74 % Mn) 27.60 0.44 0.63Mn Ore (NIST SRM 25c, 57.85 % Mn) 57.69 0.23 0.57E248073
