1、Designation: E 314 00 (Reapproved 2005)Standard Test Methods forManganese in Iron Ores1This standard is issued under the fixed designation E 314; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number i
2、n parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.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 inc
3、luded:SectionsTest Method A (Pyrophosphate (Potentiometric) 7-15Test Method B (Periodate (Photometric) 16-211.2 Test Method A covers the determination of manganesein the concentration range from 2.5 to 15.0 %. Test Method Bcovers the determination of manganese in the concentrationrange of 0.01 to 5.
4、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 1601.1.3 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard
5、.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 appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced
6、Documents2.1 ASTM Standards:2E50 Practices for Apparatus, Reagents, and Safety Precau-tions for Chemical Analysis of Metals, Ores, and RelatedMaterialsE 135 Terminology Relating to Analytical Chemistry forMetals, Ores, and Related Materials.E 173 Practice for Conducting Interlaboratory Studies ofMet
7、hods for Chemical Analysis of Metals3E 877 Practice for Sampling and Sample Preparation of IronOres and Related MaterialsE 882 Guide for Accountability and Quality Control in theChemical Analysis LaboratoryE 1601 Practice for Conducting an Interlaboratory Study toEvaluate the Performance of an Analy
8、tical Method3. Terminology3.1 DefinitionsFor definitions of terms used in this testmethod, refer to Terminology E 135.4. Significance and Use4.1 This test method is intended to be used for compliancewith compositional specifications for manganese content iniron ores, concentrates, and agglomerates.
9、It is assumed that allwho use these procedures will be trained analysts capable ofperforming 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 c
10、ontrol practices must befollowed such as those described in Guide E 882.5. Reagents and Materials5.1 Purity and Concentration of ReagentsThe purity andconcentration of the common chemical reagents used shallconform to Practices E50. Special apparatus and reagentsrequired are located in separate sect
11、ions preceding the proce-dure.6. Hazards6.1 For precautions to be observed in this method, refer toPractices E 50.7. Sampling and Sample Preparation7.1 The gross sample shall be collected and prepared inaccordance with Practice E 877.7.2 The analytical sample shall be pulverized to pass a No.100 (15
12、0-m) sieve.1These test methods 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 Oct. 1, 2005. Pu
13、blished October 2005. Originallyapproved in 1966. Last previous edition approved in 2000 as E 314 00.2For 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 D
14、ocument Summary page onthe ASTM website.3Withdrawn.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.NOTE 2To facilitate decomposition some ores, such as specularhematites, may require grinding to pass a No. 200 (75-m) sieve.TEST METHO
15、D APYROPHOSPHATE(POTENTIOMETRIC) METHOD8. Summary of Test Method8.1 The test sample is decomposed by treatment withhydrochloric, nitric, hydrofluoric, and perchloric acids. Afterthe addition of sodium pyrophosphate and the adjustment ofthe acidity, the manganese is determined by oxidation totrivalen
16、t manganese with a standard solution of potassiumpermanganate. The end point is determined 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 commerciallya
17、vailable. Many of these instruments can accept a variety ofelectrodes 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 ortra
18、nsistorized potentiometer which makes the emf balancingoperation 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 cont
19、rols. The dial must read in pH directly, andpermit readings that are accurate to at least 60.01 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, t
20、wo electrodesare used for pH measurements. These are called 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 t
21、he saturated calomelelectrode. It is most often used as a 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
22、 convenient to use, but it ismore difficult to prepare than 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 gl
23、ass electrode. The quinhydrone and antimony-antimonous oxide 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
24、disconnected from the meter and stored.When pH measurements 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
25、a long period of time.10.2 Potentiometric Titration ApparatusInstruments 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 o
26、n the fact that when twodissimilar electrodes are placed 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 poi
27、nt of the titration may bedetermined by adding the titrant 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 pot
28、en-tiometer is not necessary for potentiometric titrations becausethe absolute cell voltage needs to be known only approxi-mately, and variations of less than 1 MV are not significant.Such instruments should have a range of about 1.5 V and areadability of about 1 MV. Many of the pH meters are alsosu
29、itable for potentiometric titrations.10.2.2 The electrode system 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 cha
30、nge during the titration; further, the indicatorelectrode must 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 titra
31、nt added and thecorresponding potential differences are noted. 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
32、of the titration. Thistechnique is applicable to reasonably 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 i
33、nclude automatic recording of the titrationcurve on a strip 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-fluorocarboncoveredstirring bar is recommende
34、d.11. Reagents11.1 Hydrochloric Acid (sp gr 1.19)Concentrated hydro-chloric acid (HCl).11.2 Hydrochloric Acid (1 + 1)Mix 1 volume of concen-trated HCl (sp gr 1.19) with 1 volume of water.11.3 Hydrochloric Acid (1 + 10)Mix 1 volume of concen-trated HCl (sp gr 1.19) with 10 volumes of water.E 314 00 (
35、2005)211.4 Hydrofluoric Acid (48 %)Concentrated hydrofluoricacid (HF).11.5 Hydrogen Peroxide (3 %)Mix 1 volume of concen-trated hydrogen peroxide (H2O2, 30 %) with 9 volumes ofwater.11.6 Nitric Acid (sp gr 1.42)Concentrated nitric acid(HNO3).11.7 Perchloric Acid (70 %)(HClO4).11.8 Potassium Permanga
36、nate, Standard Solution (0.1 N)11.8.1 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 a Gooch crucible or afine porosity fritted-glass crucible. Avoid contact with rubberor other organic material. Store
37、in a dark-colored glass-stoppered bottle.11.8.2 StandardizationDry a portion of the National In-stitute of Standards and Technology standard sample of sodiumoxalate at 105C. Transfer 0.3000 g of the sodium oxalate to a600-L beaker. Add 250 mL of H2SO4(5+95) previously boiledfor 10 to 15 min and then
38、 cooled to 27 6 3C, and stir until theoxalate has dissolved.Add 39 to 40 mL (Note 3) of the KMnO4solution, at a rate of 25 to 35 mL/min, while stirring slowly. Letstand until the pink color disappears (about 45 s) (Note 4). Heatto 55 to 60C and complete the titration by adding KMnO4solution until a
39、faint pink color persists for 30 s. Add the last0.5 to 1 mL dropwise, allowing each drop to become decol-orized before adding the next drop. To determine the blank:Titrate 250 mL of H2SO4(5+95), treated as above, withKMnO4solution to a faint pink color. The blank correction isusually equivalent to 0
40、.03 3 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, 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
41、 N)(Note 5)Dilute 1 volume of 0.1 N potassium permanganatesolution with 1 volume of water. Standardize using 0.1500 g ofsodium oxalate as described under 11.8.2. Confirm the stan-dardization against an ore of known manganese content bycarrying the known sample through all steps of the procedure.NOTE
42、 5The 0.05 normality of the potassium permanganate (KMnO4)solution used (1.5803 g/L) is based on the usual valance change ofmanganese in 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
43、Mn (VII). The factor 0.04395mentioned in Section 13, therefore, is based on the following calculation:45 3 0.05494 (Mn equivalent of KMnO4in the 7 to 2 valence change).11.10 Sodium Carbonate (Na2CO3).11.11 Sodium Hydroxide Solution (200 g/L)Dissolve 200g of sodium hydroxide (NaOH) in 500 to 600 mL o
44、f water anddilute to 1 L.11.12 Sodium Pyrophosphate(Na4P2O710H2O), Satu-rated SolutionThis reagent shall be tested in the titration ofa known amount of manganese. Only lots which rapidlyprovide steady potentials shall be used.12. Procedure12.1 Transfer approximately 0.5000 g of prepared sample toa s
45、mall dry weighing bottle and place in a drying oven. Afterdrying at 105 to 110C (Note 6) for 1 h, cap the bottle, and coolto room temperature in a desiccator. Momentarily release thecap to equalize pressure and weigh the capped bottle to thenearest 0.0001 g. Repeat the drying and weighing until ther
46、e isno further weight loss. Transfer the test sample to a 600-mLbeaker and reweigh the capped bottle to the nearest 0.0001 g.The difference 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 so
47、me 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, cover, and heat below boiling. When allsoluble minerals are decomposed, add 10 mL of HNO3,4to5mL of HF, and 15 mL of HClO4and evaporate without a coverto copious fumes
48、of HClO4. Cool, and rinse down the sides ofthe beaker and dissolve the salts in 10 mL of water (Note 7).Cover and again evaporate to fumes HClO4and fume stronglyfor 1 min. Withdraw the cover slightly and volatilize anychromium present by the drop-wise addition of HCl. Whenchromyl chloride has been e
49、xpelled, as indicated by theabsence of orange vapor on the addition of HCl, replace thecover and evaporate to about 3 mL or until the salts form on thebottom of the beaker. Cool, add 10 mLof HCl (1 + 1) and 1 mLof H2O2, and boil for about 5 min.NOTE 7At this point manganese, which may have separated asmanganese dioxide (MnO2), should be dissolved by the dropwise additionof H2O2. If any residue remains, dilute with 50 mL of hot water and filterthe solution through a medium-texture paper. Wash alternately with HCl(1 + 10) and hot water until the pape
