1、Designation: E248 12Standard Test Method forDetermination of Manganese in Manganese Ores byPyrophosphate Complexed Permanganate PotentiometricTitrimetry1This standard is issued under the fixed designation E248; the number immediately following the designation indicates the year oforiginal adoption o
2、r, 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.This standard has been approved for use by agencies of the Department of Defense.1. Scope1
3、.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-priate
4、 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, Ores, andRelated Mat
5、erialsE135 Terminology Relating to Analytical Chemistry forMetals, Ores, and Related MaterialsE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test MethodE882 Guide for Accountability and Quality Control in theChemical Analysis Laboratory3. Terminology3.1 Definiti
6、onsFor definitions of terms used in this testmethod, refer to Terminology E135.4. Summary of Test Method4.1 The test sample is decomposed by treatment with HCL,HNO3, HF, and HClO4.After the addition of sodium pyrophos-phate and adjustment of the acidity, the manganese is deter-mined by oxidation to
7、trivalent manganese with a standardsolution of potassium permanganate. The end point is deter-mined potentiometrically.5. Significance and Use5.1 This definitive test method is intended to be used as areferee method for compliance with compositional specifica-tions for manganese content. It is assum
8、ed 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 befollowed. Appropriate quality control prac
9、tices must be fol-lowed such as those described in Guide E882.6. 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 Potentiometric Titration Apparatus equippe
10、d with calo-mel and platinum electrodes. A suitable pH meter may be usedfor 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 otherwise indicated, it is intended tha
11、tall 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 be1This test method is under the jurisdiction of ASTM Committee E01 onAnalytical Chemistry for Metals, Ores, and Relat
12、ed Materials and is the directresponsibility of Subcommittee E01.02 on Ores, Concentrates, and Related Metal-lurgical Materials.Current edition approved June 1, 2012. Published July 2012. Originally approvedin 1964. Last previous edition approved in 2007 as E248 07. DOI: 10.1520/E0248-12.2For refere
13、nced 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.3Reagent Chemicals, American Chemical Society Specifications, AmericanCh
14、emical Society, Washington, DC, www.chemistry.org. For suggestions on thetesting of reagents not listed by the American Chemical Society, see the UnitedStates Pharmacopeia and National Formulary, U.S. Pharmacopeial Convention,INC (USPC), Rockville, MD.1Copyright ASTM International, 100 Barr Harbor D
15、rive, PO Box C700, West Conshohocken, PA 19428-2959, United States.used, provided it is first ascertained that the reagent is ofsufficiently high purity to permit its use without lessening theaccuracy of the determination.8.2 Purity of WaterUnless otherwise indicated, referencesto water shall be und
16、erstood to mean reagent water conformingto Type I or II of Specification D1193. Type III or IV may beused if they effect no measurable change in the blank orsample.8.3 Hydrogen Peroxide (3 %)Mix 1 volume of concen-trated hydrogen peroxide (H2O2, 30 %) with 9 volumes ofwater.8.4 Potassium Permanganat
17、e, Standard Solution (0.1 N)NOTE 1The 0.1 normality of the KMnO4solution 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
18、)The factor 0.0439 used in Section 12, therefore, is based on the followingcalculation: 4/5 3 0.05494 (Mn equivalent of KMnO4in 7 to 2 valencechange).8.4.1 PreparationDissolve 3.2 g of potassium perman-ganate (KMnO4) in 1 L of water. Let stand in the dark for 2weeks. Filter, without washing, through
19、 a Gooch crucible or afine porosity fritted-glass crucible. Avoid contact with rubberor other organic material. Store in a dark-colored glass-stoppered bottle.8.4.2 StandardizationDry a portion of the National Insti-tute of Standards and Technology (NIST) standard sample, orequivalent, of sodium oxa
20、late at 105 C. Transfer 0.3000 g ofthe sodium oxalate to a 600-mL beaker. Add 250 mL of H2SO4(5 + 95), previously boiled for 10 min to 15 min and thencooled to 27 C 6 3 C, and stir until the oxalate has dissolved.Add 39 mL to 40 mL of the KMnO4solution (8.4.1), at a rateof 25 mL/min to 35 mL/min, wh
21、ile stirring slowly. Let standuntil the pink color disappears (about 45 s). Heat to 55 C to 60C and complete the titration by adding KMnO4solution(8.4.1), until a faint pink color persists for 30 s.Add the last 0.5mL to 1 mL dropwise, allowing each drop to become decolor-ized before adding the next
22、drop. To determine the blank:Titrate 250 mL of H2SO4(5 + 95), treated as above, withKMnO4solution (8.4.1) to a faint pink color. The blankcorrection is usually equivalent to 0.03 3 0.05 mL.8.5 Sodium Hydroxide Solution (200 g/L)Dissolve 200 gof sodium hydroxide (NaOH) in 500 mL to 600 mL of waterand
23、 dilute to 1 L.8.6 Sodium Pyrophosphate(Na4P2O710H2O), SaturatedSolutionThis reagent shall be tested in the 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.
24、 Sample Preparation10.1 The laboratory sample shall be pulverized, if neces-sary, so that 100 % passes a No. 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 into a drying oven
25、 and dry at 120C for 1 h. Cap the bottle and cool to room temperature in adesiccator. Loosen the stopper momentarily 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
26、weighing untilconstant weight is obtained. Transfer the sample to a 600-mLbeaker and reweigh the capped bottle to the nearest 0.1 mg.The difference between the last two weights is the mass of thesample.11.2 To the 600-mL beaker add 10 mL of concentrated HCl,10 mLof HNO3, 4 mLto 5 mLof HF, and 10 mLo
27、f HClO4andheat to affect solution. Evaporate to fumes of HClO4. Cool andrinse down the sides of the beaker. 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
28、 by drop-wise addition of HCl. When chromyl chloride has beenexpelled, as evidenced by the disappearance of any orangevapor upon HCl addition, replace the cover and evaporate to avolume of 2 mL to 3 mL or until the first appearance of saltformation on the bottom of the beaker. Cool, add 10 mL of HCl
29、(1+1),and1mLofH2O2, hydrogen peroxide (3 %) (8.3) andboil for 4 min to 5 min.NOTE 2In rare instances there may be a small amount of black 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 alterna
30、tely with hot HCl (1 + 1) and hot water until perchloratesare removed. The paper and precipitate shall be placed in a platinumcrucible, 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
31、dissolved in a little water. Thesolution of this melt shall then be added to the filtrate and the solutionagain evaporated to fumes of HClO4.11.3 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
32、 a magneticstirring device) with NaOH solution (8.5) and HCl. The testsolution should be clear and colorless. If a precipitate forms,dilute further with the Na4P2O7solution (8.6) until a clearsolution is obtained, maintaining a pH of 6.5. Cool from 10 Cto 20 C and titrate the manganese potentiometri
33、cally with the0.1 N KMnO4solution (8.4). Add the titrant rapidly until thefirst deflection of the galvanometer is noted and then dropwiseto the equivalence point. The drop giving the largest potentialchange shall be taken as the end point.NOTE 3If any pink coloration in the solution is evident at th
34、is point,the sample shall be discarded and the analysis repeated.12. Calculation12.1 Calculate the percentage of manganese as follows(Note 1):Manganese,%54.3965ABCwhere:E248 122A = KMnO4solution (8.4) required for titration of thesample, mLB = normality of the KMnO4solution (8.4), andC = sample used
35、, 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 this test method may be judged bycomparing accepted reference values with the correspondingarithmetic average obtained by interlaboratory t
36、esting. The hand k statistical values computed by Practice E691 did notexceed a critical value, which would have suggested a bias inthe results of a participating laboratory. All of the data seemconsistent, and there is no evidence that the test method gavebiased results.14. Keywords14.1 manganese c
37、ontent; manganese ores; titrimetryASTM 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 risko
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40、ur 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 multiple copies) of this standard may be obtained by co
41、ntacting 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/).4Supporting data have been filed a
42、t ASTM International Headquarters and maybe obtained by requesting Research Report RR:E01-1033.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 0.57E248 123
