Manganese ores and concentrates — Determination of manganese content — Potentiometric method

This document specifies a potentiometric method for the determination of the manganese content of manganese ores and concentrates with manganese content equal to or greater than a mass fraction of 15 %.

Minerais et concentrés de manganèse — Dosage du manganèse — Méthode potentiométrique

General Information

Status
Published
Publication Date
08-Jun-2022
Current Stage
6060 - International Standard published
Due Date
23-Oct-2021
Completion Date
09-Jun-2022
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INTERNATIONAL ISO
STANDARD 4298
Third edition
2022-06
Manganese ores and concentrates —
Determination of manganese content
— Potentiometric method
Minerais et concentrés de manganèse — Dosage du manganèse —
Méthode potentiométrique
Reference number
ISO 4298:2022(E)
© ISO 2022
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ISO 4298:2022(E)
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© ISO 2022

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© ISO 2022 – All rights reserved
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ISO 4298:2022(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ..................................................................................................................................................................................... 1

3 Terms and definitions .................................................................................................................................................................................... 1

4 Principle ........................................................................................................................................................................................................................ 1

5 Reagents ........................................................................................................................................................................................................................ 2

6 Apparatus .................................................................................................................................................................................................................... 4

7 Sampling ....................................................................................................................................................................................................................... 4

8 Procedure ....................................................................................................................................................................................................................4

8.1 Test portion ............................................................................................................................................................................................... 4

8.2 Blank test ..................................................................................................................................................................................................... 4

8.3 Determination of hygroscopic moisture content ..................................................................................................... 4

8.4 Decomposition of test portion .................................................................................................................................................. 5

8.5 Treatment of residue ......................................................................................................................................................................... 5

8.6 Titration........................................................................................................................................................................................................ 5

9 Expression of results ....................................................................................................................................................................................... 5

9.1 Calculation of manganese content ........................................................................................................................................ 5

9.2 General treatment of results ...................................................................................................................................................... 6

9.2.1 Expression of precision ................................................................................................................................................ 6

9.2.2 Determination of analytical result ..................................................................................................................... 7

9.2.3 Between-laboratories precision ........................................................................................................................... 7

9.2.4 Check for trueness ............................................................................................................................................................ 7

9.2.5 Calculation of final result ........................................................................................................................................... 8

10 Test report .................................................................................................................................................................................................................. 8

Annex A (informative) Additional information on the international interlaboratory test ......................9

Annex B (normative) Flow chart for the acceptance procedure of test results ..................................................11

Bibliography .............................................................................................................................................................................................................................12

iii
© ISO 2022 – All rights reserved
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ISO 4298:2022(E)
Foreword

ISO (the International Organization for Standardization) is a worldwide federation of national standards

bodies (ISO member bodies). The work of preparing International Standards is normally carried out

through ISO technical committees. Each member body interested in a subject for which a technical

committee has been established has the right to be represented on that committee. International

organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.

ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of

electrotechnical standardization.

The procedures used to develop this document and those intended for its further maintenance are

described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the

different types of ISO documents should be noted. This document was drafted in accordance with the

editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of

any patent rights identified during the development of the document will be in the Introduction and/or

on the ISO list of patent declarations received (see www.iso.org/patents).

Any trade name used in this document is information given for the convenience of users and does not

constitute an endorsement.

For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and

expressions related to conformity assessment, as well as information about ISO's adherence to

the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see

www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 132, Ferroalloys.

This third edition cancels and replaces the second edition (ISO 4298:1984), which has been technically

revised.
The main changes are as follows:

— in Clause 4, the description of reaction has been reworded to better explain the method;

— in 5.12 (previously in 5.10), the detailed specification of “electrolytic manganese” has been added

and described as “electrolytic manganese metal flakes”;

— in 5.13 (previously in 5.11), the commercially available standard solution has been added as an

alternative, and variations in concentration shall be taken into account for the calculation of the

results in 9.1;

— in 5.14 (previously 5.11.1), the amount of aliquot portion of the manganese standard reference

solution and the saturated sodium pyrophosphate solution has been reduced, and the specification

of the beaker has been changed;

— in 5.15 (previously 5.11.2), the amount of aliquot portion of the potassium permanganate solution

and the saturated sodium pyrophosphate solution has been reduced, and the specification of the

beaker has been changed;

— in Clause 6, the description of pH meter has been replaced with a list of potentiometric titration

apparatus in line with the current status of the development of the instrument, including the

apparatus for potentiometric titration in 6.1, pH determination in 6.2 and titration assembly in 6.3;

— in Clause 8, a new paragraph of the definition of test portion has been added in 8.1 and the amount

of test portion in 8.1 (previously 8.2) has been reduced from 1,0 g to 0,50 g;

— in Clause 8, a new paragraph of the definition and requirement of determination of hygroscopic

moisture content has been added in 8.3;
© ISO 2022 – All rights reserved
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ISO 4298:2022(E)

— in 8.4 (previously 8.2), the amount of acids has been reduced, the times of washing have been

changed, and the detailed usage of watch-glass and the provision of filter volume have been added;

— in 8.6 (previously 8.4), the amount of aliquot portion of the solution and the saturated sodium

pyrophosphate solution has been reduced, and the specification of one-mark volumetric flask and

the beaker have been changed;

— in 9.1, the formula of the manganese content has been replaced with three new calculating formulae

which take into account the hygroscopic moisture content of the test portion;

— in 9.2, the paragraph of the “permissible tolerances on results” has been replaced with the “general

treatment of results”;
— Clause 10, the test report has been added;

— Annex A, “Additional information on the international interlaboratory test” has been added;

— Annex B, “Flow sheet of the procedure for the acceptance of teat results” has been added.

Any feedback or questions on this document should be directed to the user’s national standards body. A

complete listing of these bodies can be found at www.iso.org/members.html.
© ISO 2022 – All rights reserved
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INTERNATIONAL STANDARD ISO 4298:2022(E)
Manganese ores and concentrates — Determination of
manganese content — Potentiometric method
1 Scope

This document specifies a potentiometric method for the determination of the manganese content of

manganese ores and concentrates with manganese content equal to or greater than a mass fraction of

15 %.
2 Normative references

The following documents are referred to in the text in such a way that some or all of their content

constitutes requirements of this document. For dated references, only the edition cited applies. For

undated references, the latest edition of the referenced document (including any amendments) applies.

ISO 310, Manganese ores and concentrates — Determination of hygroscopic moisture content in analytical

samples — Gravimetric method
ISO 648, Laboratory glassware — Single-volume pipettes
ISO 1042, Laboratory glassware — One-mark volumetric flasks
ISO 3696, Water for analytical laboratory use — Specification and test methods
ISO 4296-1, Manganese ores — Sampling — Part 1: Increment sampling
ISO 4296-2, Manganese ores — Sampling — Part 2: Preparation of samples
ISO 80000-1:2009, Quantities and units — Part 1: General
3 Terms and definitions
No terms and definitions are listed in this document.

ISO and IEC maintain terminology databases for use in standardization at the following addresses:

— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
4 Principle

The method is based on the titration of manganous ion with permanganate ion in neutral pyrophosphate

solution, the manganese(II) being oxidized, the permanganate ion reduced, to a pyrophosphate complex

2+ −
of the +3 state (the stoichiometry ratio of Mn to MnO is 4:1).

Decomposition of a test portion by treatment with hydrochloric acid, nitric, perchloric and hydrofluoric

acids. Separation of insoluble residue, and reservation of the filtrate as the main solution. Ignition of

the residue, fusion with sodium carbonate, leaching of the melt with hydrochloric acid and combination

with the main solution. Addition of an aliquot portion of the resulting solution to sodium pyrophosphate

solution, adjustment of the pH to 7,0, and potentiometric titration with potassium permanganate

standard volumetric solution.
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ISO 4298:2022(E)
5 Reagents

During the analysis, unless otherwise stated, use only reagents of recognized analytical grade and only

grade 3 water as specified in ISO 3696.
5.1 Sodium carbonate (Na CO ), anhydrous.
2 3
5.2 Hydrochloric acid, ρ = 1,19 g/ml.
5.3 Hydrofluoric acid, ρ = 1,14 g/ml.
5.4 Perchloric acid, ρ = 1,51 g/ml.
5.5 Nitric acid, ρ = 1,40 g/ml.
5.6 Potassium permanganate, degree of purity not less than 99,5 %.
5.7 Sodium carbonate, 50 g/l solution.
5.8 Hydrochloric acid, diluted 1 + 4.

5.9 Saturated sodium pyrophosphate solution. Dissolve 120 g of sodium pyrophosphate

decahydrate (Na P O ·10H O) with 1 000 ml of water. After 24 h, the supernatant is obtained for use.

4 2 7 2

5.10 Potassium-permanganate (KMnO ), recrystallized. Dissolve 250 g of potassium permanganate

(5.6) with 800 ml of hot water (90 °C) in a 1 000 ml beaker. Filter the solution under vacuum through a

filter crucible with a sintered glass plate No.3 (6.5). Cool the filtered solution in an ice bath to 10 °C, while

stirring vigorously. Allow the fine-grained precipitate to settle. Then pour out the solution, transfer the

crystalline mass to the crucible with sintered glass plate No.3 (6.5) and place under suction. Repeat the

recrystallization.

After thorough suction, transfer the crystalline mass thus obtained to a glass or porcelain dish and

dry in air in the dark, protecting from dust. When the crystalline mass no longer sticks together when

crushed with a glass rod, dry it at 80 °C to 100 °C for 2 h to 3 h in a drying oven. Then transfer it to a

stoppered brown glass bottle.

Potassium permanganate thus obtained contains 34,76 % (mass fraction) of manganese and is non-

hygroscopic.
5.11 Bromothymol blue indicator, 0,4 g/l solution.

5.12 Manganese, standard reference solution, corresponding to 1 g of Mn per litre. Place 10,00 g of

electrolytic manganese metal flakes (purity not less than 99,95 %) in a 400 ml or 500 ml beaker. Add a

mixture of 50 ml of water and 5 ml of the nitric acid (5.5) and leave for a few minutes until the surface

becomes bright. Wash the treated manganese six times with water, then with acetone, and dry at 100 °C

for 10 min.

Place 1,00 g of the treated electrolytic manganese in a 400 ml or 500 ml beaker, and add 20 ml of sulfuric

acid (ρ = 1,84 g/ ml, diluted 1 + 1) and about 100 ml of water. Boil the solution for a few minutes, cool,

transfer to a 1 000 ml one-mark volumetric flask, dilute to the mark with water and mix.

1 ml of this standard solution contains 1 mg of Mn.
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ISO 4298:2022(E)

5.13 Potassium permanganate, standard volumetric solution, c (1/5 KMnO ) ≈ 0,1 mol/l. Dissolve

3,20 g of potassium permanganate (5.6) in 1 000 ml of water, allow to stand for six days, then transfer

to a brown glass bottle and mix.

Alternatively, commercially available standard solutions of known concentration can be used instead of

standard solutions produced in the laboratory. Variations in concentration shall be taken into account

for the calculation of the results.
5.14 Standardization with the manganese standard reference solution (5.12).

Transfer 50,00 ml of the manganese standard reference solution (5.12) into a 400 ml beaker and

add, while stirring, 150 ml of the saturated sodium pyrophosphate solution (5.9). Adjust the pH of

the solution to 7,0 with hydrochloric acid (5.8) [check the pH using either the pH electrode (6.2) or

the bromothymol blue indicator (5.11)] and titrate with the potassium permanganate solution (5.13)

using the potentiometric titration apparatus (6.1, 6.2, 6.3) until the maximum peak deflection on the

voltmeter is observed.
Carry out a blank test, omitting the standard manganese solution.

The mass concentration of the potassium permanganate solution, ρ , is given by Formula (1):

ρ = (1)
VV−
where

m is the mass, in grams, of manganese present in the aliquot portion of the manganese

stand
...

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