1、Designation: E316 11Standard Test Method forDetermination of Iron in Manganese Ores by HydrogenSulfide Reduction-Dichromate Titrimetry1This standard is issued under the fixed designation E316; the number immediately following the designation indicates the year oforiginal adoption or, in the case of
2、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 iron inmanganese ore in the range from2%to20%.NOTE
3、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 other units of measurement are included in thisstandard.1.3 This standard do
4、es 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 safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Sta
5、ndards:2D1193 Specification for Reagent WaterE50 Practices for Apparatus, Reagents, and Safety Consid-erations for Chemical Analysis of Metals, Ores, andRelated MaterialsE135 Terminology Relating to Analytical Chemistry forMetals, Ores, and Related MaterialsE882 Guide for Accountability and Quality
6、Control in theChemical Analysis Laboratory3. Terminology3.1 DefinitionsFor definitions of terms used in this testmethod, refer to Terminology E135.4. Summary of Test Method4.1 The sample is decomposed by treatment with hydro-chloric, hydrofluoric, and sulfuric acids. Any residue is treatedfor the re
7、covery of insoluble iron. The iron is reduced withhydrogen sulfide, the insoluble sulfides are removed by filtra-tion, and the excess hydrogen sulfide is expelled by boiling.After cooling, the reduced iron is titrated with a standardpotassium dichromate solution using sodium diphenylaminesulfonate a
8、s the indicator.5. Significance and Use5.1 This test method is intended to be used for compliancewith compositional specifications for iron content in manga-nese ores. It is assumed that all who use these procedures willbe trained analysts capable of performing common laboratoryprocedures skillfully
9、 and safely. It is expected that work will beperformed in a properly equipped laboratory and that properwaste disposal procedures will be followed. Appropriate qual-ity control practices must be followed such as those describedin Guide E882.6. Interferences6.1 None of the elements normally found in
10、manganese oreinterfere with this test method.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 onAnalytical Reagents of the American Chemical Soc
11、iety wheresuch specifications are available3. Other grades may be used,provided it is first ascertained that the reagent is of sufficientlyhigh purity to permit its use without lessening the accuracy ofthe determination.7.2 Purity of WaterUnless otherwise indicated, referencesto water shall be under
12、stood 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.1This test method is under the jurisdiction of ASTM Committee E01 onAnalytical Chemistry for Metals, Ores, and Related Materials and is th
13、e directresponsibility of Subcommittee E01.02 on Ores, Concentrates, and Related Metal-lurgical Materials.Current edition approved Sept. 1, 2011. Published September 2011. Originallyapproved in 1967. Last previous edition approved in 2005 as E316 00 (2005).DOI: 10.1520/E0316-11.2For referenced ASTM
14、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 Chemical, American Chemical Society Specifications, AmericanChemical Soci
15、ety, Washington, DC. For suggestions on the testing of reagents notlisted by the American Chemical Society, see Analar Standards for LaboratoryChemicals, BDH Ltd., Poole Dorset, U. K., and the United States Pharmacopeiaand National Formulary, U.S. Pharmaceutical Convention, Inc., (USPC), Rockville,M
16、D1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.7.3 Ferrous Ammonium Sulfate Solution (approx. 0.10N)Dissolve 40 g of ferrous ammonium sulfate(FeSO4(NH4)2SO46H2O) in sulfuric acid (1 + 19). Transfer toa 1-L flask and dilute to volum
17、e with sulfuric acid (1 + 19).When the sample solution is ready for titration, standardize theFeSO4(NH4)2SO46H2O solution against the standard potas-sium dichromate solution (0.1000 N)(7.7) as described in 11.1.Calculate the millilitres of standard potassium dichromatesolution equivalent to 1 mL of
18、the FeSO4(NH4)2SO46H2Osolution.7.4 Hydrogen Sulfide(H2S).7.5 Hydrogen Sulfide Wash Solution.7.5.1 Saturate H2SO4(1 + 99) with hydrogen sulfide (H2S).Prepare fresh as needed.7.6 Phosphoric Acid (85 %)Concentrated phosphoric acid(H3PO4).7.7 Potassium Dichromate, Standard Solution (0.1000 N)7.7.1 Disso
19、lve 4.9035 g of Primary Standard Grade potas-sium dichromate (K2Cr2O4) in water, transfer to a 1-L volu-metric flask, dilute to volume, and mix.7.8 Sodium Diphenylamine Sulfonate Indicator Solution (2g/L).7.8.1 Dissolve 0.20 g of sodium diphenylamine sulfonate in100 mL of water. Store in a dark-colo
20、red bottle.7.9 Sodium Pyrosulfate (Na2S2O7).8. Hazards8.1 For precautions to be observed in this method, refer toPractices E50.9. Sampling and Sample Preparation9.1 The test unit shall be collected and prepared to maintainthe representative iron content in the lot.9.2 The laboratory sample shall be
21、pulverized to pass a No.100 (150-m) sieve.9.3 Weigh approximately (within 6 25 mg) an amount oftest sample specified as follows:Content of Iron, % Weight of Sample, g2to10 2.010 to 20 1.010. Procedure10.1 Transfer the test sample to a small, dry weighing bottleand place into a drying oven.After dryi
22、ng at 120 C for 1 h, capthe bottle and cool to room temperature in a desiccator.Momentarily release the cap to equalize pressure and weigh thecapped bottle to the nearest 0.1 mg. Repeat the drying andweighing until there is no further weight loss. Transfer the testsample to a 400-mL beaker and rewei
23、gh the capped bottle tothe nearest 0.1 mg. The difference between the two masses isthe mass of the sample.10.2 Moisten the sample with a few millilitres of water, add15 mL of HCl, cover and heat gently until no further attack isapparent. Add 5 mL of HNO3and warm until the actionsubsides.Add 10 drops
24、 to 15 drops of HF and 15 mLof H2SO4,and heat to copious fumes of SO3(do not prolong fuming).Cool, rinse the sides of the beaker with a few millilitres ofwater, and again heat to fumes of SO3. Cool, add 100 mL ofwater, and heat to boiling.10.3 Filter off any residue through a medium texture paperint
25、o a 400-mL beaker and wash the paper and residue with hotwater until the iron color is removed from the paper. Reservethe filtrate.10.4 Ignite the paper and residue in a platinum crucible,cool, moisten with a few drops of water, and add 3 drops to 4drops of H2SO4(1 + 1) and 5 mL of HF. Evaporate slo
26、wly toexpel the silica and the excess H2SO4.Add3gofNa2S2O7tothe crucible and fuse over a burner until a clear melt isobtained. Dissolve the cool melt in a few millilitres of waterand add this solution and the washings of the crucible andcover to the reserved filtrate.10.5 Dilute the solution with wa
27、ter to a volume of 250 mLand heat to boiling. Remove from the heat source and pass arapid stream of H2S through the solution for 15 min. Digest at60 C for 15 min and filter through a medium texture paperwith the aid of paper pulp into a 500-mL Erlenmeyer flask.Wash the precipitated sulfides thorough
28、ly with the hydrogensulfide wash solution. Add a few glass beads to the flask toprevent bumping, heat the solution to boiling, and boil for 15min to 20 min to completely expel the H2S. (Check with leadacetate test paper.) Remove from the heat source, cover theflask with a small watch glass, and cool
29、 to 20 C in runningwater.10.6 To the cool solution add 5 mL of H3PO4and 5 drops ofthe sodium diphenylamine sulfonic indicator solution. Dilutewith water to approximately 300 mL and titrate with thestandard K2Cr2O7solution to a distinct purple end point.11. Blank Determination11.1 Determine the blank
30、 value of the reagents concurrentlywith the test determination, using the same amount of allreagents and following all the steps of the procedure. Imme-diately before titrating with the K2Cr2O7solution, add 1.0 mL,accurately measured, of the FeSO4(NH4)2SO46H2O solution.In another beaker place 350 mL
31、 of cold H2SO4(1 + 19) andadd an accurately measured 1 mL of theFeSO4(NH4)2SO46H2O solution. Add 5 mL of sodium diphe-nylamine sulfonate indicator solution and titrate with theK2Cr2O7solution. Record this titration and subtract from thetitration of the blank solution to obtain the corrected blank.NO
32、TE 2In the absence of iron, the sodium diphenylamine sulfonateindicator does not react with the K2Cr2O7solution. The addition of theFeSO4(NH4)2SO46H2O is, therefore, necessary to promote indicatorresponse in the blank solution. A correction must be made in terms of itsequivalent in millilitres of K2
33、Cr2O7solution.12. Calculation12.1 Calculate the iron content as follows:Iron, % 5FA 2 B! 3 CDG3 100 (1)E316 112where:A = millilitres of K2Cr2O7solution required for titration ofsample,B = millilitres of K2Cr2O7solution required for titration ofblank,C = iron value of K2Cr2O7in grams per millilitre,
34、andD = grams of sample used.13. Precision and Bias13.1 PrecisionTable 1 indicates the precision of this testmethod between laboratories using standard samples as theunknowns.13.2 BiasNo information on the bias of this test method isknown. Accepted values for the reference materials used in theinterl
35、aboratory study are not available for evaluation. Users ofthe method are encouraged to employ accepted referencematerials, if available, and to judge the bias of the method fromthe difference between the accepted value for the iron contentand the mean value of the reference material.14. Keywords14.1
36、 dichromate titrimetry; iron content; manganese oreASTM 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 righ
37、ts, 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 reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for
38、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 theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing
39、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 multiple copies) of this standard may
40、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/).TABLE 1 Statistical InformationAverage IronContent,A%Relative StandardDeviation, %Number ofDeter-minationsNumber ofParticipatingLaboratories5.18 6 0.7 17 85.57 6 1.6 17 8AEach average iron content represents a different kind of manganese ore.E316 113
