1、Designation: E314 10 (Reapproved 2015)1Standard Test Methods forDetermination of Manganese in Iron Ores by Pyrophosphate(Potentiometric) and Periodate (Spectrophotometric)Techniques1This standard is issued under the fixed designation E314; the number immediately following the designation indicates t
2、he year oforiginal adoption or, 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.1NOTEEditorial changes made throughout E314 in November 2015.
3、1. Scope1.1 These test methods cover the determination of manga-nese in iron ores, concentrates, and agglomerates. The follow-ing two test methods are included:SectionsTest Method A (Pyrophosphate (Potentiometric) 815Test Method B (Periodate (Photometric) 16221.2 Test Method A covers the determinati
4、on of manganesein the range from 2.5 % to 15.0 %. Test Method B covers thedetermination of manganese in the range of 0.01 % to 5.00 %.NOTE 1The lower limit for this test method is set at 50 % relativeerror for the lowest grade material tested in the interlaboratory study inaccordance with Practice E
5、1601.1.3 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.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 establish
6、 appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2E50 Practices for Apparatus, Reagents, and Safety Consid-erations for Chemical Analysis of Metals, Ores, andRelated MaterialsE135 Terminology R
7、elating to Analytical Chemistry forMetals, Ores, and Related MaterialsE173 Practice for Conducting Interlaboratory Studies ofMethods for Chemical Analysis of Metals (Withdrawn1998)3E877 Practice for Sampling and Sample Preparation of IronOres and Related Materials for Determination of Chemi-cal Comp
8、osition and Physical PropertiesE882 Guide for Accountability and Quality Control in theChemical Analysis LaboratoryE1601 Practice for Conducting an Interlaboratory Study toEvaluate the Performance of an Analytical Method3. Terminology3.1 DefinitionsFor definitions of terms used in these testmethods,
9、 refer to Terminology E135.4. Significance and Use4.1 This test method is intended to be used for compliancewith compositional specifications for manganese content iniron ores, concentrates, and agglomerates. It is assumed that allwho use these procedures will be trained analysts capable ofperformin
10、g common laboratory procedures skillfully andsafely. It is expected that work will be performed in a properlyequipped laboratory and that proper waste disposal procedureswill be followed.Appropriate quality control practices must befollowed such as those described in Guide E882.5. Reagents and Mater
11、ials5.1 Purity of ReagentsThe purity of the common chemicalreagents used shall conform to Practices E50. Special appara-tus and reagents required are located in separate sectionspreceding the procedure.6. Hazards6.1 For precautions to be observed in this method, refer toPractices E50.1These test met
12、hods are under the jurisdiction of ASTM Committee E01 onAnalytical Chemistry for Metals, Ores, and Related Materials and are the directresponsibility of Subcommittee E01.02 on Ores, Concentrates, and Related Metal-lurgical Materials.Current edition approved Nov. 15, 2015. Published December 2015. Or
13、iginallyapproved in 1966. Last previous edition approved in 2010 as E314 10. DOI:10.1520/E0314-10R15E01.2For 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 standard
14、s Document Summary page onthe ASTM website.3The last approved version of this historical standard is referenced onwww.astm.org.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States17. Sampling and Sample Preparation7.1 The gross sample shal
15、l be collected and prepared inaccordance with Practice E877.7.2 The analytical sample shall be pulverized to pass a No.100 (150-m) sieve.NOTE 2To facilitate decomposition some ores, such as specularhematites, may require grinding to pass a No. 200 (75-m) sieve.TEST METHOD APYROPHOSPHATE(POTENTIOMETR
16、IC) METHOD8. Summary of Test Method8.1 The test sample is decomposed by treatment with HCl,HNO3, HF, and HClO4.After the addition of sodium pyrophos-phate and the adjustment of the acidity, the manganese isdetermined by oxidation to trivalent manganese with a standardsolution of potassium permangana
17、te. The end point is deter-mined potentiometrically.9. Interferences9.1 Provision has been made for the removal of chromiumwhich under some conditions is an interfering element.10. Apparatus10.1 pH MeterA number of pH meters are commerciallyavailable. Many of these instruments can accept a variety o
18、felectrodes and therefore can be used also for potential mea-surements.Although both line- and battery-operated pH metersare manufactured, the former is recommended for laboratorywork because this type of pH meter contains an electronic ortransistorized potentiometer which makes the emf balancingope
19、ration entirely automatic. Electrometer tube input is usedon both the electronic and transistorized pH meters.10.1.1 The pH meter must have electrode standardization(or asymmetry potential) and manual or automatic temperaturecompensation controls. The dial must read in pH directly, andpermit reading
20、s that are accurate to at least 6 0.01 pH unit. Forhigher accuracies it is recommended that a pH meter with anexpanded scale be used.10.1.2 Because there is no accurate method for determiningthe absolute potential of an individual electrode, two electrodesare used for pH measurements. These are call
21、ed the referenceand indicator electrodes. By international agreement the hy-drogen electrode is the standard indicator electrode for pH, butis inconvenient to use and subject to several limitations. Themost widely used reference electrode is the saturated calomelelectrode. It is most often used as a
22、 pencil-type unit that isimmersed directly in the solution, but may also be utilized asan external cell (to prevent possible contamination) contactingthe solution by means of a salt bridge. The silver-silverchloride reference electrode is also convenient to use, but it ismore difficult to prepare th
23、an the saturated calomel electrode.The mercurous sulfate reference electrode may be used insolutions in which the chloride ions that diffuse out of thecalomel cell might be harmful.10.1.3 The most commonly employed indicator electrode isthe glass electrode. The quinhydrone and antimony-antimonous ox
24、ide electrodes are used to a much lesser extent.Combination electrodes containing both the indicator andreference units are also available. The tips of the electrodescontaining solutions must be covered with rubber caps whenthe electrodes are disconnected from the meter and stored.When pH measuremen
25、ts are not being made the electrodesconnected to the pH meter should be kept in a beakercontaining water. Prior to measuring the pH of a solution theelectrodes must be thoroughly washed with water especially ifthey have been left standing for a long period of time.10.2 Potentiometric Titration Appar
26、atusInstruments fordetecting the end points in pH (acid-base), oxidation-reduction,precipitation, and complexation titrations consist of a pair ofsuitable electrodes, a potentiometer, a buret, and a motor-driven stirrer. Titrations are based on the fact that when twodissimilar electrodes are placed
27、in a solution there is a potentialdifference between them. This potential difference depends onthe composition of the solution and changes as the titrant isadded. A high-impedance electronic voltmeter follows thechanges accurately. The end point of the titration may bedetermined by adding the titran
28、t until the potential differenceattains a predetermined value or by plotting the potentialdifference versus the titrant volume, the titrant being addeduntil the end point has been passed.10.2.1 An elaborate or highly sensitive and accurate poten-tiometer is not necessary for potentiometric titration
29、s becausethe absolute cell voltage needs to be known onlyapproximately, and variations of less than 1 mV are notsignificant. Such instruments should have a range of about1.5 V and a readability of about 1 mV. Many of the pH metersare also suitable for potentiometric titrations.10.2.2 The electrode s
30、ystem must consist of a referenceelectrode and an indicator electrode. The reference electrodemaintains a constant, but not necessarily a known or reproduc-ible potential during the titration. The potential of the indicatorelectrode does change during the titration; further, the indicatorelectrode m
31、ust be one that will quickly come to equilibrium.Aplatinum indicator electrode and reference electrode are re-quired for this method.10.2.3 Initially, a titration of the constituent in question isperformed manually, and the volumes of titrant added and thecorresponding potential differences are note
32、d. By use ofestablished techniques the end point potential is determined.For the analytical determinations, titration may be continued toa preset potential, the end point being signaled by a null meter,with or without automatic termination of the titration. Thistechnique is applicable to reasonably
33、rapid reactions involvingstrong oxidants and reductants, precipitates not more solublethan silver chloride, and ionization constants greater than thatof boric acid.10.2.4 Other techniques may be used for both slow and fastreactions. These include automatic recording of the titrationcurve on a strip
34、chart, and the recording of the titrant end pointvolume on a tape. In the latter, an adjustable print-out delayprevents undertitrating when the reaction is slow.10.3 Magnetic StirrerUse of a TFE-fluorocarbon-coveredstirring bar is recommended.E314 10 (2015)1211. Reagents11.1 Hydrochloric Acid (sp gr
35、 1.19)Concentrated.11.2 Hydrochloric Acid (1 + 1)Mix one volume of con-centrated HCl (sp gr 1.19) with one volume of water.11.3 Hydrochloric Acid (1 + 10)Mix one volume of con-centrated HCl (sp gr 1.19) with ten volumes of water.11.4 Hydrofluoric Acid (48 %)Concentrated.11.5 Hydrogen Peroxide (3 %)M
36、ix one volume of con-centrated hydrogen peroxide (H2O2, 30 %) with nine volumesof water.11.6 Nitric Acid (sp gr 1.42)Concentrated HNO3.11.7 Perchloric Acid (70 %).11.8 Potassium Permanganate, Standard Solution (0.1 N).11.8.1 PreparationDissolve 3.2 g of potassium perman-ganate (KMnO4) in 1 L of wate
37、r. Let stand in the dark for twoweeks. Filter, without washing, through a Gooch crucible or afine porosity fritted-glass crucible. Avoid contact with rubberor other organic material. Store in a dark-colored glass-stoppered bottle.11.8.2 StandardizationDry a portion of a sample of so-dium oxalate at
38、105 C. Transfer 0.3000 g of the sodiumoxalate to a 600-L beaker. Add 250 mL of H2SO4(5 + 95)previously boiled for 10 min to 15 min and then cooled to27 C 6 3 C, and stir until the oxalate has dissolved. Add39 mL to 40 mL (Note 3) of the KMnO4solution, at a rate of25 mLmin to 35 mLmin, while stirring
39、 slowly. Let standuntil the pink color disappears (about 45 s) (Note 4). Heat to55 C to 60 C and complete the titration by adding KMnO4solution until a faint pink color persists for 30 s. Add the last0.5 mL to 1 mL dropwise, allowing each drop to becomedecolorized before adding the next drop. To det
40、ermine theblank: Titrate 250 mL of H2SO4(5 + 95), treated as above,with KMnO4solution to a faint pink color. The blank correc-tion is usually equivalent to 0.03 mL to 0.05 mL.NOTE 3A 0.3000-g portion of sodium oxalate requires 44.77 mL ofKMnO4solution (0.1 N).NOTE 4If the KMnO4solution is too strong
41、, the pink color will notfade at this point; begin again, adding a few millilitres less of the KMnO4solution.11.9 Potassium Permanganate, Standard Solution (0.05 N)(Note 5)Dilute one volume of 0.1 N potassium permangan-ate solution with one volume of water. Standardize using0.1500 g of sodium oxalat
42、e as described under 11.8.2. Confirmthe standardization against an ore of known manganese contentby carrying the known sample through all steps of theprocedure.NOTE 5The 0.05 normality of the potassium permanganate (KMnO4) solution used (1.5803 g L) is based on the usual valance change ofmanganese i
43、n acid solution from 7 to 2. In the test method described, themanganese in the sample is oxidized from Mn (II) to Mn (III) while theKMnO4is reduced from Mn (III) to Mn (VII). The factor 0.04395mentioned in Section 13, therefore, is based on the following calculation:45 0.05494 (Mn equivalent of KMnO
44、4in the (7 to 2) valence change).11.10 Sodium Carbonate (Na2CO3).11.11 Sodium Hydroxide Solution (200 gL)Dissolve200 g of sodium hydroxide (NaOH) in 500 mL to 600 mL ofwater and dilute to 1 L.11.12 Sodium Pyrophosphate (Na4P2O710H2O), SaturatedSolutionThis reagent shall be tested in the titration of
45、 aknown amount of manganese. Only lots which rapidly providesteady potentials shall be used.12. Procedure12.1 Transfer approximately 0.5000 g of prepared sample toa small dry weighing bottle and place in a drying oven. Afterdrying at 105 C to 110 C (Note 6) for 1 h, cap the bottle, andcool to room t
46、emperature in a desiccator. Momentarily releasethe cap to equalize pressure and weigh the capped bottle to thenearest 0.0001 g. Repeat the drying and weighing until there isno further weight loss. Transfer the test sample to a 600-mLbeaker and reweigh the capped bottle to the nearest 0.0001 g.The di
47、fference between the two weights is the weight of the testsample.NOTE 6Most ores yield their hygroscopic moisture at the specifiedtemperature. However, in the case of some ores, higher drying tempera-tures may be required.12.2 Moisten the test sample with a few millilitres of water,add 20 mL of HCl,
48、 cover, and heat below boiling. When allsoluble minerals are decomposed, add 10 mL of HNO3,4mLto 5 mL of HF, and 15 mL of HClO4and evaporate without acover to copious fumes of HClO4. Cool, and rinse down thesides of the beaker and dissolve the salts in 10 mL of water(Note 7). Cover and again evapora
49、te to fumes of HClO4andfume strongly for 1 min. Withdraw the cover slightly andvolatilize any chromium present by the drop-wise addition ofHCl. When chromyl chloride has been expelled, as indicatedby the absence of orange vapor on the addition of HCl, replacethe cover and evaporate to about 3 mLor until the salts form onthe bottom of the beaker. Cool, add 10 mL of HCl (1 + 1) and1mLofH2O2, and boil for about 5 min.NOTE 7At this point manganese, which may have separated asmanganese dioxide (MnO2), should be dissolved by the dropwise ad
