ASTM E314-00
(Test Method)Standard Test Methods for Manganese in Iron Ores
Standard Test Methods for Manganese in Iron Ores
SCOPE
1.1 These test methods cover the determination of manganese in iron ores, concentrates, and agglomerates. The following two test methods are included: SectionsTest Method A (Pyrophosphate (Potentiometric))7-15Test Method B (Periodate (Photometric))16-21
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.
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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Designation:E314–00
Standard Test Methods for
Manganese in Iron Ores
This standard is issued under the fixed designation E 314; 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 (e) indicates an editorial change since the last revision or reapproval.
1. Scope 3. Terminology
1.1 These test methods cover the determination of manga- 3.1 Definitions—For definitions of terms used in this test
nese in iron ores, concentrates, and agglomerates. The follow- method, refer to Terminology E 135.
ing two test methods are included:
4. Significance and Use
Sections
Test Method A (Pyrophosphate (Potentiometric)) 7-15
4.1 This test method is intended to be used for compliance
Test Method B (Periodate (Photometric)) 16-21
with compositional specifications for manganese content in
1.2 Test Method A covers the determination of manganese iron ores, concentrates, and agglomerates. It is assumed that all
in the concentration range from 2.5 to 15.0 %. Test Method B who use these procedures will be trained analysts capable of
covers the determination of manganese in the concentration performing common laboratory procedures skillfully and
range of 0.01 to 5.00 %. safely. It is expected that work will be performed in a properly
equipped laboratory and that proper waste disposal procedures
NOTE 1—The lower limit for this test method is set at 50 % relative
will be followed.Appropriate quality control practices must be
error for the lowest grade material tested in the interlaboratory study in
followed such as those described in Guide E 882.
accordance with Practice E 1601.
1.3 This standard does not purport to address all of the
5. Reagents and Materials
safety concerns, if any, associated with its use. It is the
5.1 Purity and Concentration of Reagents—The purity and
responsibility of the user of this standard to establish appro-
concentration of the common chemical reagents used shall
priate safety and health practices and determine the applica-
conform to Practices E 50. Special apparatus and reagents
bility of regulatory limitations prior to use.
required are located in separate sections preceding the proce-
dure.
2. Referenced Documents
2.1 ASTM Standards:
6. Hazards
E 50 Practices for Apparatus, Reagents, and Safety Precau-
6.1 For precautions to be observed in this method, refer to
tions for Chemical Analysis of Metals
Practice E 50.
E 135 Terminology Relating to Analytical Chemistry for
Metals, Ores, and Related Materials.
7. Sampling and Sample Preparation
E 173 Practice for Conducting Interlaboratory Studies of
7.1 The gross sample shall be collected and prepared in
Methods for Chemical Analysis of Metals
accordance with Practice E 877.
E 877 PracticeforSamplingandSamplePreparationofIron
7.2 The analytical sample shall be pulverized to pass a No.
Ores and Related Materials
100 (150-µm) sieve.
E 882 Guide for Accountability and Quality Control in the
NOTE 2—To facilitate decomposition some ores, such as specular
Chemical Analysis Laboratory
hematites, may require grinding to pass a No. 200 (75-µm) sieve.
E 1601 Practice for Conducting an Interlaboratory Study to
Evaluate the Performance of an Analytical Method
TEST METHOD A—PYROPHOSPHATE
(POTENTIOMETRIC) METHOD
These test methods are under the jurisdiction of ASTM Committee E01 on
8. Summary of Test Method
Analytical Chemistry for Metals, Ores, and Related Materials and are the direct
responsibility of Subcommittee E01.02 on Ores, Concentrates, and Related Metal-
8.1 The test sample is decomposed by treatment with
lurgical Materials.
hydrochloric, nitric, hydrofluoric, and perchloric acids. After
Current edition approved Nov. 10, 2000. Published January 2001. Originally
the addition of sodium pyrophosphate and the adjustment of
published as E 314 – 66 T. Last previous edition E 314 – 95.
the acidity, the manganese is determined by oxidation to
Annual Book of ASTM Standards, Vol 03.05.
Discontinued 1997; see 1996 Annual Book of ASTM Standards, Vol 03.05.
Annual Book of ASTM Standards, Vol 03.06.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
E314
trivalent manganese with a standard solution of potassium added. A high-impedance electronic voltmeter follows the
permanganate. The end point is determined potentiometrically. changes accurately. The end point of the titration may be
determined by adding the titrant until the potential difference
9. Interferences
attains a predetermined value or by plotting the potential
9.1 Provision has been made for the removal of chromium
difference versus the titrant volume, the titrant being added
which under some conditions is an interfering element.
until the end point has been passed.
10.2.1 An elaborate or highly sensitive and accurate poten-
10. Apparatus
tiometer is not necessary for potentiometric titrations because
10.1 pH Meter—A number of pH meters are commercially
the absolute cell voltage needs to be known only approxi-
available. Many of these instruments can accept a variety of
mately, and variations of less than 1 MV are not significant.
electrodes and therefore can be used also for potential mea-
Such instruments should have a range of about 1.5 V and a
surements.Although both line- and battery-operated pH meters
readability of about 1 MV. Many of the pH meters are also
are manufactured, the former is recommended for laboratory
suitable for potentiometric titrations.
work because this type of pH meter contains an electronic or
10.2.2 The electrode system must consist of a reference
transistorized potentiometer which makes the emf balancing
electrode and an indicator electrode. The reference electrode
operation entirely automatic. Electrometer tube input is used
maintains a constant, but not necessarily a known or reproduc-
on both the electronic and transistorized pH meters.
ible potential during the titration. The potential of the indicator
10.1.1 The pH meter must have electrode standardization
electrodedoeschangeduringthetitration;further,theindicator
(or asymmetry potential) and manual or automatic temperature
electrode must be one that will quickly come to equilibrium.A
compensation controls. The dial must read in pH directly, and
platinum indicator electrode and reference electrode are re-
permit readings that are accurate to at least 60.01 pH unit. For
quired for this method.
higher accuracies it is recommended that a pH meter with an
10.2.3 Initially, a titration of the constituent in question is
expanded scale be used.
performed manually, and the volumes of titrant added and the
10.1.2 Because there is no accurate method for determining
corresponding potential differences are noted. By use of
theabsolutepotentialofanindividualelectrode,twoelectrodes
established techniques the end point potential is determined.
are used for pH measurements. These are called the reference
For the analytical determinations, titration may be continued to
and indicator electrodes. By international agreement the hy-
a preset potential, the end point being signaled by a null meter,
drogen electrode is the standard indicator electrode for pH, but
with or without automatic termination of the titration. This
is inconvenient to use and subject to several limitations. The
technique is applicable to reasonably rapid reactions involving
most widely used reference electrode is the saturated calomel
strong oxidants and reductants, precipitates not more soluble
electrode. It is most often used as a pencil-type unit that is
than silver chloride, and ionization constants greater than that
immersed directly in the solution, but may also be utilized as
of boric acid.
an external cell (to prevent possible contamination) contacting
10.2.4 Other techniques may be used for both slow and fast
the solution by means of a salt bridge. The silver-silver
reactions. These include automatic recording of the titration
chloride reference electrode is also convenient to use, but it is
curve on a strip chart, and the recording of the titrant end point
more difficult to prepare than the saturated calomel electrode.
volume on a tape. In the latter, an adjustable print-out delay
The mercurous sulfate reference electrode may be used in
prevents undertitrating when the reaction is slow.
solutions in which the chloride ions that diffuse out of the
10.3 Magnetic Stirrer— Use of a TFE-fluorocarboncovered
calomel cell might be harmful.
stirring bar is recommended.
10.1.3 The most commonly employed indicator electrode is
11. Reagents
the glass electrode. The quinhydrone and antimony-
antimonous oxide electrodes are used to a much lesser extent. 11.1 Hydrochloric Acid (sp gr 1.19)—Concentrated hydro-
Combination electrodes containing both the indicator and chloric acid (HCl).
reference units are also available. The tips of the electrodes 11.2 Hydrochloric Acid (1 + 1)—Mix 1 volume of concen-
containing solutions must be covered with rubber caps when trated HCl (sp gr 1.19) with 1 volume of water.
the electrodes are disconnected from the meter and stored. 11.3 Hydrochloric Acid (1 + 10)—Mix 1 volume of concen-
When pH measurements are not being made the electrodes trated HCl (sp gr 1.19) with 10 volumes of water.
connected to the pH meter should be kept in a beaker 11.4 Hydrofluoric Acid (48 %)—Concentrated hydrofluoric
containing water. Prior to measuring the pH of a solution the acid (HF).
electrodes must be thoroughly washed with water especially if 11.5 Hydrogen Peroxide (3 %)—Mix 1 volume of concen-
they have been left standing for a long period of time. trated hydrogen peroxide (H O , 30 %) with 9 volumes of
2 2
10.2 Potentiometric Titration Apparatus—Instruments for water.
detectingtheendpointsinpH(acid-base),oxidation-reduction, 11.6 Nitric Acid (sp gr 1.42)—Concentrated nitric acid
precipitation, and complexation titrations consist of a pair of (HNO ).
suitable electrodes, a potentiometer, a buret, and a motor- 11.7 Perchloric Acid (70 %)—(HClO ).
driven stirrer. Titrations are based on the fact that when two 11.8 Potassium Permanganate, Standard Solution (0.1 N)
dissimilarelectrodesareplacedinasolutionthereisapotential 11.8.1 Preparation—Dissolve 3.2 g of potassium perman-
difference between them. This potential difference depends on ganate (KMnO ) in 1 L of water. Let stand in the dark for 2
the composition of the solution and changes as the titrant is weeks. Filter, without washing, through a Gooch crucible or a
E314
TABLE 1 Precision Data
fine porosity fritted-glass crucible. Avoid contact with rubber
or other organic material. Store in a dark-colored glass- Number of Number of
Relative Standard
A
Average Concentration, % Deter- Participating
B
stoppered bottle.
Deviation, %
minations Laboratories
11.8.2 Standardization—Dry a portion of the National In-
2.80 61.87 14 7
stituteofStandardsandTechnologystandardsampleofsodium
4.12 61.75 14 7
oxalate at 105°C. Transfer 0.3000 g of the sodium oxalate to a
5.53 61.16 14 7
7.81 60.68 14 7
600-Lbeaker.Add 250 mLof H SO (5+95) previously boiled
2 4
10.09 61.02 14 7
for 10 to 15 min and then cooled to 27 6 3°C, and stir until the
A
Each concentration represents a different kind of iron ore.
oxalatehasdissolved.Add39to40mL(Note3)oftheKMnO
4 B
RelativeStandardDeviation, RSD,inthistestmethodiscalculatedasfollows:
solution,atarateof25to35mL/min,whilestirringslowly.Let
RSD 5 100/¯X (d /n–1
~ != !
standuntilthepinkcolordisappears(about45s)(Note4).Heat
where:
to 55 to 60°C and complete the titration by adding KMnO
¯
X = average concentration, %,
solution until a faint pink color persists for 30 s. Add the last
d = difference of the determination from the mean, and
0.5 to 1 mL dropwise, allowing each drop to become decol-
n = number of determinations, and in this case n = 7 as each value used is
the average of two determinations from each laboratory.
orized before adding the next drop. To determine the blank:
Titrate 250 mL of H SO (5+95), treated as above, with
2 4
KMnO solution to a faint pink color. The blank correction is
usually equivalent to 0.03 3 0.05 mL. temperature. However, in the case of some ores, higher drying tempera-
tures may be required.
NOTE 3—A 0.3000-g portion of sodium oxalate requires 44.77 mL of
12.2 Moisten the test sample with a few millilitres of water,
KMnO solution (0.1 N).
add 20 mL of HCl, cover, and heat below boiling. When all
NOTE 4—If the KMnO solution is too strong, the pink color will not
soluble minerals are decomposed, add 10 mL of HNO,4to5
fade at this point; begin again, adding a few millilitres less of the KMnO
solution.
mLof HF, and 15 mLof HClO and evaporate without a cover
to copious fumes of HClO . Cool, and rinse down the sides of
11.9 Potassium Permanganate, Standard Solution (0.05 N)
the beaker and dissolve the salts in 10 mL of water (Note 7).
(Note 5)—Dilute 1 volume of 0.1 N potassium permanganate
Cover and again evaporate to fumes HClO and fume strongly
solution with 1 volume of water. Standardize using 0.1500 g of
for 1 min. Withdraw the cover slightly and volatilize any
sodium oxalate as described under 11.8.2. Confirm the stan-
chromium present by the drop-wise addition of HCl. When
dardization against an ore of known manganese content by
chromyl chloride has been expelled, as indicated by the
carrying the known sample through all steps of the procedure.
absence of orange vapor on the addition of HCl, replace the
NOTE 5—The 0.05 normality of the potassium permanganate (KMnO ) coverandevaporatetoabout3mLoruntilthesaltsformonthe
solution used (1.5803 g/L) is based on the usual valance change of
bottomofthebeaker.Cool,add10mLofHCl(1 + 1)and1mL
manganese in acid solution from 7 to 2. In the test method described, the
of H O , and boil for about 5 min.
2 2
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
NOTE 7—At this point manganese, which may have separated as
mentioned in Section 13, therefore, is based on the following calculation:
manganese dioxide (MnO ), should be dissolved by the dropwise addition
⁄5 3 0.05494 (Mn equivalent of KMnO in the 7 to 2 valence change).
of H O . If any residue remains, dilute with 50 mLof hot water and filter
2 2
the solution through a medium-texture paper. Wash alternately with HCl
11.10 Sodium Carbonate (Na CO ).
2 3
(1 + 10) and hot water until the paper is free of iron stain, and then with
11.11 Sodium Hydroxide Solution (200 g/L)—Dissolve 200
hot water until perchlorates are removed. Reserve the filtrate.
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