ASTM E314-10(2015)e1
(Test Method)Standard Test Methods for Determination of Manganese in Iron Ores by Pyrophosphate (Potentiometric) and Periodate (Spectrophotometric) Techniques
Standard Test Methods for Determination of Manganese in Iron Ores by Pyrophosphate (Potentiometric) and Periodate (Spectrophotometric) Techniques
SIGNIFICANCE AND USE
4.1 This test method is intended to be used for compliance with compositional specifications for manganese content in iron ores, concentrates, and agglomerates. It is assumed that all who use these procedures will be trained analysts capable of performing common laboratory procedures skillfully and safely. It is expected that work will be performed in a properly equipped laboratory and that proper waste disposal procedures will be followed. Appropriate quality control practices must be followed such as those described in Guide E882.
SCOPE
1.1 These test methods cover the determination of manganese in iron ores, concentrates, and agglomerates. The following two test methods are included:
Sections
Test Method A (Pyrophosphate (Potentiometric))
8 – 15
Test Method B (Periodate (Photometric))
16 – 22
1.2 Test Method A covers the determination of manganese in the range from 2.5 % to 15.0 %. Test Method B covers the determination of manganese in the range of 0.01 % to 5.00 %.
Note 1: The lower limit for this test method is set at 50 % relative error for the lowest grade material tested in the interlaboratory study in accordance with Practice E1601.
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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´1
Designation: E314 − 10 (Reapproved 2015)
Standard Test Methods for
Determination of Manganese in Iron Ores by Pyrophosphate
(Potentiometric) and Periodate (Spectrophotometric)
Techniques
This standard is issued under the fixed designation E314; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
ε NOTE—Editorial changes made throughout E314 in November 2015.
1. Scope Metals, Ores, and Related Materials
E173Practice for Conducting Interlaboratory Studies of
1.1 These test methods cover the determination of manga-
Methods for Chemical Analysis of Metals (Withdrawn
nese in iron ores, concentrates, and agglomerates. The follow-
1998)
ing two test methods are included:
E877Practice for Sampling and Sample Preparation of Iron
Sections
Ores and Related Materials for Determination of Chemi-
Test Method A (Pyrophosphate (Potentiometric)) 8–15
Test Method B (Periodate (Photometric)) 16–22 cal Composition and Physical Properties
E882Guide for Accountability and Quality Control in the
1.2 Test Method A covers the determination of manganese
Chemical Analysis Laboratory
in the range from 2.5% to 15.0%. Test Method B covers the
E1601Practice for Conducting an Interlaboratory Study to
determination of manganese in the range of 0.01% to 5.00%.
Evaluate the Performance of an Analytical Method
NOTE 1—The lower limit for this test method is set at 50% relative
error for the lowest grade material tested in the interlaboratory study in
3. Terminology
accordance with Practice E1601.
3.1 Definitions—For definitions of terms used in these test
1.3 The values stated in SI units are to be regarded as
methods, refer to Terminology E135.
standard. No other units of measurement are included in this
standard.
4. Significance and Use
1.4 This standard does not purport to address all of the
4.1 This test method is intended to be used for compliance
safety concerns, if any, associated with its use. It is the
with compositional specifications for manganese content in
responsibility of the user of this standard to establish appro-
ironores,concentrates,andagglomerates.Itisassumedthatall
priate safety and health practices and determine the applica-
who use these procedures will be trained analysts capable of
bility of regulatory limitations prior to use.
performing common laboratory procedures skillfully and
safely. It is expected that work will be performed in a properly
2. Referenced Documents
equipped laboratory and that proper waste disposal procedures
2.1 ASTM Standards:
willbefollowed.Appropriatequalitycontrolpracticesmustbe
E50Practices for Apparatus, Reagents, and Safety Consid-
followed such as those described in Guide E882.
erations for Chemical Analysis of Metals, Ores, and
Related Materials 5. Reagents and Materials
E135Terminology Relating to Analytical Chemistry for
5.1 Purity of Reagents—Thepurityofthecommonchemical
reagents used shall conform to Practices E50. Special appara-
tus and reagents required are located in separate sections
These test methods are under the jurisdiction of ASTM Committee E01 on
preceding the procedure.
Analytical Chemistry for Metals, Ores, and Related Materials and are the direct
responsibility of Subcommittee E01.02 on Ores, Concentrates, and Related Metal-
6. Hazards
lurgical Materials.
Current edition approved Nov. 15, 2015. Published December 2015. Originally
6.1 For precautions to be observed in this method, refer to
approved in 1966. Last previous edition approved in 2010 as E314–10. DOI:
Practices E50.
10.1520/E0314-10R15E01.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on The last approved version of this historical standard is referenced on
the ASTM website. www.astm.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
´1
E314 − 10 (2015)
7. Sampling and Sample Preparation Combination electrodes containing both the indicator and
reference units are also available. The tips of the electrodes
7.1 The gross sample shall be collected and prepared in
containing solutions must be covered with rubber caps when
accordance with Practice E877.
the electrodes are disconnected from the meter and stored.
7.2 The analytical sample shall be pulverized to pass a No.
When pH measurements are not being made the electrodes
100 (150-µm) sieve.
connected to the pH meter should be kept in a beaker
NOTE 2—To facilitate decomposition some ores, such as specular containing water. Prior to measuring the pH of a solution the
hematites, may require grinding to pass a No.200 (75-µm) sieve.
electrodes must be thoroughly washed with water especially if
they have been left standing for a long period of time.
TEST METHOD A—PYROPHOSPHATE
(POTENTIOMETRIC) METHOD
10.2 Potentiometric Titration Apparatus—Instruments for
detectingtheendpointsinpH(acid-base),oxidation-reduction,
8. Summary of Test Method
precipitation, and complexation titrations consist of a pair of
8.1 The test sample is decomposed by treatment with HCl,
suitable electrodes, a potentiometer, a buret, and a motor-
HNO ,HF,andHClO .Aftertheadditionofsodiumpyrophos-
3 4 driven stirrer. Titrations are based on the fact that when two
phate and the adjustment of the acidity, the manganese is
dissimilarelectrodesareplacedinasolutionthereisapotential
determinedbyoxidationtotrivalentmanganesewithastandard
difference between them. This potential difference depends on
solution of potassium permanganate. The end point is deter-
the composition of the solution and changes as the titrant is
mined potentiometrically.
added. A high-impedance electronic voltmeter follows the
changes accurately. The end point of the titration may be
9. Interferences
determined by adding the titrant until the potential difference
9.1 Provision has been made for the removal of chromium
attains a predetermined value or by plotting the potential
which under some conditions is an interfering element.
difference versus the titrant volume, the titrant being added
until the end point has been passed.
10. Apparatus
10.2.1 An elaborate or highly sensitive and accurate poten-
10.1 pH Meter—A number of pH meters are commercially
tiometer is not necessary for potentiometric titrations because
available. Many of these instruments can accept a variety of
the absolute cell voltage needs to be known only
electrodes and therefore can be used also for potential mea-
approximately, and variations of less than 1mV are not
surements.Althoughbothline-andbattery-operatedpHmeters
significant. Such instruments should have a range of about
are manufactured, the former is recommended for laboratory
1.5V and a readability of about 1mV. Many of the pH meters
work because this type of pH meter contains an electronic or
are also suitable for potentiometric titrations.
transistorized potentiometer which makes the emf balancing
10.2.2 The electrode system must consist of a reference
operation entirely automatic. Electrometer tube input is used
electrode and an indicator electrode. The reference electrode
on both the electronic and transistorized pH meters.
maintains a constant, but not necessarily a known or reproduc-
10.1.1 The pH meter must have electrode standardization
iblepotentialduringthetitration.Thepotentialoftheindicator
(orasymmetrypotential)andmanualorautomatictemperature
electrodedoeschangeduringthetitration;further,theindicator
compensation controls. The dial must read in pH directly, and
electrode must be one that will quickly come to equilibrium.A
permitreadingsthatareaccuratetoatleast 60.01pHunit.For
platinum indicator electrode and reference electrode are re-
higher accuracies it is recommended that a pH meter with an
quired for this method.
expanded scale be used.
10.1.2 Because there is no accurate method for determining 10.2.3 Initially, a titration of the constituent in question is
theabsolutepotentialofanindividualelectrode,twoelectrodes performed manually, and the volumes of titrant added and the
are used for pH measurements. These are called the reference
corresponding potential differences are noted. By use of
and indicator electrodes. By international agreement the hy-
established techniques the end point potential is determined.
drogen electrode is the standard indicator electrode for pH, but
Fortheanalyticaldeterminations,titrationmaybecontinuedto
is inconvenient to use and subject to several limitations. The
apresetpotential,theendpointbeingsignaledbyanullmeter,
most widely used reference electrode is the saturated calomel
with or without automatic termination of the titration. This
electrode. It is most often used as a pencil-type unit that is
technique is applicable to reasonably rapid reactions involving
immersed directly in the solution, but may also be utilized as
strong oxidants and reductants, precipitates not more soluble
an external cell (to prevent possible contamination) contacting
than silver chloride, and ionization constants greater than that
the solution by means of a salt bridge. The silver-silver
of boric acid.
chloride reference electrode is also convenient to use, but it is
10.2.4 Other techniques may be used for both slow and fast
more difficult to prepare than the saturated calomel electrode.
reactions. These include automatic recording of the titration
The mercurous sulfate reference electrode may be used in
curveonastripchart,andtherecordingofthetitrantendpoint
solutions in which the chloride ions that diffuse out of the
volume on a tape. In the latter, an adjustable print-out delay
calomel cell might be harmful.
prevents undertitrating when the reaction is slow.
10.1.3 The most commonly employed indicator electrode is
10.3 Magnetic Stirrer—Use of a TFE-fluorocarbon-covered
the glass electrode. The quinhydrone and antimony-
antimonous oxide electrodes are used to a much lesser extent. stirring bar is recommended.
´1
E314 − 10 (2015)
11. Reagents 11.11 Sodium Hydroxide Solution (200 g⁄L)—Dissolve
200g of sodium hydroxide (NaOH) in 500mL to 600mL of
11.1 Hydrochloric Acid (sp gr 1.19)—Concentrated.
water and dilute to 1L.
11.2 Hydrochloric Acid (1+1)—Mix one volume of con-
11.12 Sodium Pyrophosphate (Na P O ·10H O), Saturated
4 2 7 2
centrated HCl (spgr1.19) with one volume of water.
Solution—This reagent shall be tested in the titration of a
known amount of manganese. Only lots which rapidly provide
11.3 Hydrochloric Acid (1+10)—Mix one volume of con-
centrated HCl (spgr1.19) with ten volumes of water. steady potentials shall be used.
11.4 Hydrofluoric Acid (48%)—Concentrated.
12. Procedure
11.5 Hydrogen Peroxide (3%)—Mix one volume of con-
12.1 Transferapproximately0.5000gofpreparedsampleto
centrated hydrogen peroxide (H O , 30%) with nine volumes
2 2
a small dry weighing bottle and place in a drying oven. After
of water.
drying at 105°C to 110°C (Note 6) for 1h, cap the bottle, and
11.6 Nitric Acid (sp gr 1.42)—Concentrated HNO . cool to room temperature in a desiccator. Momentarily release
the cap to equalize pressure and weigh the capped bottle to the
11.7 Perchloric Acid (70%).
nearest 0.0001g. Repeat the drying and weighing until there is
11.8 Potassium Permanganate, Standard Solution (0.1 N).
no further weight loss. Transfer the test sample to a 600-mL
beaker and reweigh the capped bottle to the nearest 0.0001g.
11.8.1 Preparation—Dissolve 3.2g of potassium perman-
Thedifferencebetweenthetwoweightsistheweightofthetest
ganate (KMnO ) in 1Lof water. Let stand in the dark for two
sample.
weeks. Filter, without washing, through a Gooch crucible or a
fine porosity fritted-glass crucible. Avoid contact with rubber
NOTE 6—Most ores yield their hygroscopic moisture at the specified
or other organic material. Store in a dark-colored glass-
temperature. However, in the case of some ores, higher drying tempera-
stoppered bottle.
tures may be required.
11.8.2 Standardization—Dry a portion of a sample of so-
12.2 Moisten the test sample with a few millilitres of water,
dium oxalate at 105°C. Transfer 0.3000g of the sodium
add 20mL of HCl, cover, and heat below boiling. When all
oxalate to a 600-L beaker. Add 250mL of H SO (5+95)
2 4
soluble minerals are decomposed, add 10mLof HNO ,4mL
previously boiled for 10min to 15min and then cooled to
to 5mL of HF, and 15mL of HClO and evaporate without a
27°C 63°C, and stir until the oxalate has dissolved. Add
cover to copious fumes of HClO . Cool, and rinse down the
39mL to 40mL (Note 3) of the KMnO solution, at a rate of
sides of the beaker and dissolve the salts in 10mL of water
25mL⁄min to 35mL⁄min, while stirring slowly. Let stand
(Note 7). Cover and again evaporate to fumes of HClO and
until the pink color disappears (about 45s) (Note 4). Heat to
fume strongly for 1min. Withdraw the cover slightly and
55°C to 60°C and complete the titration by adding KMnO
volatilize any chromium present by the drop-wise addition of
solution until a faint pink color persists for 30s. Add the last
HCl. When chromyl chloride has been expelled, as indicated
0.5mL to 1mL dropwise, allowing each drop to become
bytheabsenceoforangevaporontheadditionofHCl,replace
decolorized before adding the next drop. To determine the
thecoverandevaporatetoabout3mLoruntilthesaltsformon
blank: Titrate 250mL of H SO (5+95), treated as above,
2 4
the bottom of the beaker. Cool, add 10mL of HCl (1+1) and
with KMnO solution to a faint pink color. The blank correc-
1mLofH O , and boil for about 5min.
2 2
tion is usually equivalent to 0.03mLto 0.05mL.
NOTE 7—At this point manganese, which may have separated as
NOTE 3—A 0.3000-g portion of sodium oxalate requires 44.77mL of
manganesedioxide(MnO ),shouldbedissolvedbythedropwiseaddition
KMnO solution (0.1 N).
4 of H O . If any residue remains, dilute with 50mLof hot water and filter
2 2
NOTE 4—If the KMnO solution is too strong, the pink color will not
the solution through a medium-texture paper. Wash alternately with HCl
fade at this point; begin again, adding a few millilitres less of the KMnO (1+10) and hot water until the paper is free of iron stain, and then with
solution.
hot water until perchlorates are removed. Reserve the filtrate. Place the
paper and residue in a platinum crucible. Dry and ignite to destroy all
11.9 Potassium Permanganate, Standard Solution (0.05 N)
carbonaceous matter.Add 1g of Na CO to the crucible and fuse until a
2 3
(Note
...
This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
´1
Designation: E314 − 10 E314 − 10 (Reapproved 2015)
Standard Test Methods for
Determination of Manganese in Iron Ores by Pyrophosphate
(Potentiometric) and Periodate
(Photometric)(Spectrophotometric) Techniques
This standard is issued under the fixed designation E314; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
ε NOTE—Editorial changes made throughout E314 in November 2015.
1. Scope
1.1 These test methods cover the determination of manganese in iron ores, concentrates, and agglomerates. The following two
test methods are included:
Sections
Test Method A (Pyrophosphate (Potentiometric)) 8 – 15
Test Method B (Periodate (Photometric)) 16 – 22
1.2 Test Method A covers the determination of manganese in the concentration range from 2.5 % to 15.0 %. Test Method B
covers the determination of manganese in the concentration range of 0.01 % to 5.00 %.
NOTE 1—The lower limit for this test method is set at 50 % relative error for the lowest grade material tested in the interlaboratory study in accordance
with Practice E1601.
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory
limitations prior to use.
2. Referenced Documents
2.1 ASTM Standards:
E50 Practices for Apparatus, Reagents, and Safety Considerations for Chemical Analysis of Metals, Ores, and Related Materials
E135 Terminology Relating to Analytical Chemistry for Metals, Ores, and Related Materials
E173 Practice for Conducting Interlaboratory Studies of Methods for Chemical Analysis of Metals (Withdrawn 1998)
E877 Practice for Sampling and Sample Preparation of Iron Ores and Related Materials for Determination of Chemical
Composition and Physical Properties
E882 Guide for Accountability and Quality Control in the Chemical Analysis Laboratory
E1601 Practice for Conducting an Interlaboratory Study to Evaluate the Performance of an Analytical Method
3. Terminology
3.1 Definitions—For definitions of terms used in these test methods, refer to Terminology E135.
4. Significance and Use
4.1 This test method is intended to be used for compliance with compositional specifications for manganese content in iron ores,
concentrates, and agglomerates. It is assumed that all who use these procedures will be trained analysts capable of performing
These test methods are under the jurisdiction of ASTM Committee E01 on Analytical Chemistry for Metals, Ores, and Related Materials and are the direct responsibility
of Subcommittee E01.02 on Ores, Concentrates, and Related Metallurgical Materials.
Current edition approved June 15, 2010Nov. 15, 2015. Published August 2010December 2015. Originally approved in 1966. Last previous edition approved in 20052010
as E314 – 00 (2005).E314 – 10. DOI: 10.1520/E0314-10.10.1520/E0314-10R15E01.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
The last approved version of this historical standard is referenced on www.astm.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
´1
E314 − 10 (2015)
common laboratory procedures skillfully and safely. It is expected that work will be performed in a properly equipped laboratory
and that proper waste disposal procedures will be followed. Appropriate quality control practices must be followed such as those
described in Guide E882.
5. Reagents and Materials
5.1 Purity and Concentration of Reagents—The purity and concentration of the common chemical reagents used shall conform
to Practices E50. Special apparatus and reagents required are located in separate sections preceding the procedure.
6. Hazards
6.1 For precautions to be observed in this method, refer to Practices E50.
7. Sampling and Sample Preparation
7.1 The gross sample shall be collected and prepared in accordance with Practice E877.
7.2 The analytical sample shall be pulverized to pass a No. 100 (150-μm) sieve.
NOTE 2—To facilitate decomposition some ores, such as specular hematites, may require grinding to pass a No. 200 (75-μm) sieve.
TEST METHOD A—PYROPHOSPHATE (POTENTIOMETRIC) METHOD
8. Summary of Test Method
8.1 The test sample is decomposed by treatment with HCl, NHOHNO , HF, and HClO . After the addition of sodium
3 4
pyrophosphate and the adjustment of the acidity, the manganese is determined by oxidation to trivalent manganese with a standard
solution of potassium permanganate. The end point is determined potentiometrically.
9. Interferences
9.1 Provision has been made for the removal of chromium which under some conditions is an interfering element.
10. Apparatus
10.1 pH Meter—A number of pH meters are commercially available. Many of these instruments can accept a variety of
electrodes and therefore can be used also for potential measurements. Although both line- and battery-operated pH meters are
manufactured, the former is recommended for laboratory work because this type of pH meter contains an electronic or
transistorized potentiometer which makes the emf balancing operation entirely automatic. Electrometer tube input is used on both
the electronic and transistorized pH meters.
10.1.1 The pH meter must have electrode standardization (or asymmetry potential) and manual or automatic temperature
compensation controls. The dial must read in pH directly, and permit readings that are accurate to at least 6 0.01 pH unit. For
higher accuracies it is recommended that a pH meter with an expanded scale be used.
10.1.2 Because there is no accurate method for determining the absolute potential of an individual electrode, two electrodes are
used for pH measurements. These are called the reference and indicator electrodes. By international agreement the hydrogen
electrode is the standard indicator electrode for pH, but is inconvenient to use and subject to several limitations. The most widely
used reference electrode is the saturated calomel electrode. It is most often used as a pencil-type unit that is immersed directly in
the solution, but may also be utilized as an external cell (to prevent possible contamination) contacting the solution by means of
a salt bridge. The silver-silver chloride reference electrode is also convenient to use, but it is more difficult to prepare than the
saturated calomel electrode. The mercurous sulfate reference electrode may be used in solutions in which the chloride ions that
diffuse out of the calomel cell might be harmful.
10.1.3 The most commonly employed indicator electrode is the glass electrode. The quinhydrone and antimony-antimonous
oxide electrodes are used to a much lesser extent. Combination electrodes containing both the indicator and reference units are also
available. The tips of the electrodes containing solutions must be covered with rubber caps when the electrodes are disconnected
from the meter and stored. When pH measurements are not being made the electrodes connected to the pH meter should be kept
in a beaker containing water. Prior to measuring the pH of a solution the electrodes must be thoroughly washed with water
especially if they have been left standing for a long period of time.
10.2 Potentiometric Titration Apparatus—Instruments for detecting the end points in pH (acid-base), oxidation-reduction,
precipitation, and complexation titrations consist of a pair of suitable electrodes, a potentiometer, a buret, and a motor-driven
stirrer. Titrations are based on the fact that when two dissimilar electrodes are placed in a solution there is a potential difference
between them. This potential difference depends on the composition of the solution and changes as the titrant is added. A
high-impedance electronic voltmeter follows the changes accurately. The end point of the titration may be determined by adding
the titrant until the potential difference attains a predetermined value or by plotting the potential difference versus the titrant
volume, the titrant being added until the end point has been passed.
´1
E314 − 10 (2015)
10.2.1 An elaborate or highly sensitive and accurate potentiometer is not necessary for potentiometric titrations because the
absolute cell voltage needs to be known only approximately, and variations of less than 1 MV1 mV are not significant. Such
instruments should have a range of about 1.5 V and a readability of about 1 MV.1 mV. Many of the pH meters are also suitable
for potentiometric titrations.
10.2.2 The electrode system must consist of a reference electrode and an indicator electrode. The reference electrode maintains
a constant, but not necessarily a known or reproducible potential during the titration. The potential of the indicator electrode does
change during the titration; further, the indicator electrode must be one that will quickly come to equilibrium. A platinum indicator
electrode and reference electrode are required for this method.
10.2.3 Initially, a titration of the constituent in question is performed manually, and the volumes of titrant added and the
corresponding potential differences are noted. By use of established techniques the end point potential is determined. For the
analytical determinations, titration may be continued to a preset potential, the end point being signaled by a null meter, with or
without automatic termination of the titration. This technique is applicable to reasonably rapid reactions involving strong oxidants
and reductants, precipitates not more soluble than silver chloride, and ionization constants greater than that of boric acid.
10.2.4 Other techniques may be used for both slow and fast reactions. These include automatic recording of the titration curve
on a strip chart, and the recording of the titrant end point volume on a tape. In the latter, an adjustable print-out delay prevents
undertitrating when the reaction is slow.
10.3 Magnetic Stirrer—Use of a TFE-fluorocarboncoveredTFE-fluorocarbon-covered stirring bar is recommended.
11. Reagents
11.1 Hydrochloric Acid (sp gr 1.19)—Concentrated HCl.1.19)—Concentrated.
11.2 Hydrochloric Acid (1 + 1)—Mix one volume of concentrated HCl (sp gr 1.19) with one volume of water.
11.3 Hydrochloric Acid (1 + 10)—Mix one volume of concentrated HCl (sp gr 1.19) with ten volumes of water.
11.4 Hydrofluoric Acid (48 %)—Concentrated HF.(48 %)—Concentrated.
11.5 Hydrogen Peroxide (3 %)—Mix one volume of concentrated hydrogen peroxide (H O , 30 %) with nine volumes of water.
2 2
11.6 Nitric Acid (sp gr 1.42)—Concentrated HNO .
11.7 Perchloric Acid (70 %)—(HClO(70 %). ).
11.8 Potassium Permanganate, Standard Solution (0.1 N).
11.8.1 Preparation—Dissolve 3.2 g of potassium permanganate (KMnO ) in 1 L of water. Let stand in the dark for two weeks.
Filter, without washing, through a Gooch crucible or a fine porosity fritted-glass crucible. Avoid contact with rubber or other
organic material. Store in a dark-colored glass-stoppered bottle.
11.8.2 Standardization—Dry a portion of the National Institute of Standards and Technology (NIST) standard a sample of
sodium oxalate at 105 °C. Transfer 0.3000 g of the sodium oxalate to a 600-L beaker. Add 250 mL of H SO (5 + 95) previously
2 4
boiled for 10 min to 15 min and then cooled to 27 °C 6 3 °C, and stir until the oxalate has dissolved. Add 39 mL to 40 mL (Note
3) of the KMnO solution, at a rate of 25 mL ⁄min to 35 mL ⁄min, while stirring slowly. Let stand until the pink color disappears
(about 45 s) (Note 4). Heat to 55 °C to 60 °C and complete the titration by adding KMnO solution until a faint pink color persists
for 30 s. Add the last 0.5 mL to 1 mL dropwise, allowing each drop to become decolorized before adding the next drop. To
determine the blank: Titrate 250 mL of H SO (5 + 95), treated as above, with KMnO solution to a faint pink color. The blank
2 4 4
correction is usually equivalent to 0.03 mL × 0.05 mL. 0.03 mL to 0.05 mL.
NOTE 3—A 0.3000-g portion of sodium oxalate requires 44.77 mL of KMnO solution (0.1 N).
NOTE 4—If the KMnO solution is too strong, the pink color will not fade at this point; begin again, adding a few millilitres less of the KMnO solution.
4 4
11.9 Potassium Permanganate, Standard Solution (0.05 N) (Note 5)—Dilute one volume of 0.1 N potassium permanganate
solution with one volume of water. Standardize using 0.1500 g of sodium oxalate as described under 11.8.2. Confirm the
standardization against an ore of known manganese content by carrying the known sample through all steps of the procedure.
NOTE 5—The 0.05 normality of the potassium permanganate (KMnO ) solution used (1.5803 g ⁄L) is based on the usual valance change of manganese
in acid solution from 7 to 2. In the test method described, the manganese in the sample is oxidized from Mn (II) to Mn (III) while the KMnO is reduced
from Mn (III) to Mn (VII). The factor 0.04395 mentioned in Section 13, therefore, is based on the following calculation: ⁄5 × 0.05494 (Mn equivalent
of KMnO in the (7 to 2) valence change).
11.10 Sodium Carbonate (Na CO ).
2 3
11.11 Sodium Hydroxide Solution (200 g ⁄L)—Dissolve 200 g of sodium hydroxide (NaOH) in 500 mL to 600 mL of water and
dilute to 1 L.
11.12 Sodium Pyrophosphate (Na P O ·10H O), Saturated Solution—This reagent shall be tested in the titration of a known
4 2 7 2
amount of manganese. Only lots which rapidly provide steady potentials shall be used.
´1
E314 − 10 (2015)
12. Procedure
12.1 Transfer approximately 0.5000 g of prepared sample to a small dry weighing bottle and place in a drying oven. After drying
at 105 °C to 110 °C (Note 6) for 1 h, cap the bottle, and cool to room temperature in a desiccator. Momentarily release the cap
to equalize pressure and weigh the capped bottle to the nearest 0.0001 g. Repeat the drying and weighing until there is no f
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