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UDC 669.74
IS0
I N T ERN AT I O NA L O RG AN I2 AT I O N FOR STA ND AR D I Z AT I O N
IS0 RECOMMENDATION
R 319
METHODS OF CHEMICAL ANALYSIS OF MANGANESE ORES
DETERMINATION OF TOTAL MANGANESE CONTENT
1st EDITION
July 1963
COPYRIGHT RESERVED
The copyright of IS0 Recommendations and IS0 Standards
belongs to IS0 Member Bodies. Reproduction of these
documents, in any country, may be authorized therefore only
by the national standards organization of that country, being
a member of ISO.
For each individual country the only valid standard is the national standard of that country.
Printed in Switzerland
Also issued in French and Russian. Copies to be obtained through the national standards organizations.
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BRIEF HISTORY
The IS0 Recommendation R 319, Methods of Chemical Analysis of Manganese
Ores - Determination of Total Manganese Content, was drawn up by Technical
Committee ISO/TC 65, Manganese Ores, the Secretariat of which is held by the Komitet
Standartov, Mer i Izmeritel’nyh Priborov pri Sovete Ministrov SSSR.
Work on this question by the Technical Committee began in 1954 and led, in 1957,
to the adoption of a Draft IS0 Recommendation.
In October 1958, this Draft IS0 Recommendation (No. 252) was circulated to all
the IS0 Member Bodies for enquiry. It was approved by the following Member Bodies:
Austria Hungary Portugal
Bulgaria India Republic of
Ireland South Africa
Burma
Chile Italy Romania
Czechoslovakia Japan Spain
France Netherlands United Kingdom
U.S.S.R.
Germany Poland
No Member Body opposed the approval of the Draft.
The Draft IS0 Recommendation was then submitted by correspondence to the IS0
Council, which decided, in July 1963, to accept it as an IS0 RECOMMENDATION.
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IS0 / R 319 - 1963 (E)
R 319 July 1963
IS0 Recommendation
METHODS OF CHEMIC& ANALYSIS OF MANGANESE ORES
DETERMINATION OF TOTAL MANGANESE CONTENT
(Atomic mass Mn : 54.94; molecular mass MnOz : 86.94)
This IS0 Recommendation contains three parts :
I. Introduction . section 1,
II. Bismuthate method . sections 2 to 6,
III. Volumetric permanganate method . sections 7 to 11.
I. INTRODUCTION
1. GENERAL INSTRUCTIONS
1.1 In the following analysis, use a sample for chemical analysis of air-dried manganese ore, which
has been crushed to a size not exceeding O. 10 mm and checked on a sieve of appropriate size.
Simultaneously with the collection of samples for the determination of total manganese,
take three more test samples for the determination of hygroscopic moisture.
Calculate the content of total manganese in ore which is absolutely dry, by multiplying the
numerical results of the determination of total manganese by the conversion factor K, as
found from the following formula:
1 O0
K=-
100- A
where
A = hygroscopic moisture content, per cent.
1.2 The determination of total manganese in manganese ore is carried out by simultaneously
analysing three samples of ore, with two blank determinations to enable a corresponding
correction in the result of the determination to be made.
Simultaneously and under the same conditions, carry out a check analysis of a standard
sample of manganese ore, for total manganese content.
The arithmetical mean of the three results is accepted as the final result.
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IS0 / R 319 - 1963 (E)
The following conditions should be observed:
The maximum difference between the highest and the lowest results should not exceed double
the absolute value of the permissible tolerance on the result of the analysis (for the correspond-
ing interval of total manganese content), shown in the tables under clauses 6.2 and 11.2,
" Accuracy of method ".
The average result of the simultaneous check analysis of the standard sample of manganese
ore for total manganese content should not differ from the result shown in the certificate by
more than the f value of the permissible tolerance (for the corresponding interval of total
manganese content), shown in the tables under clauses 6.2 and 1 1.2, " Accuracy of method ".
For the analysis, take a standard sample of the type of ore to which the sample being analysed
belongs.
1.3 The test samples and the residues should be weighed to an accuracy of f 0.0002 g.
1.4 Distilled water should be used during the procedure and for the preparation of solutions.
1.5 Meanings of the following expressions :
hot water (or solution) implies a temperature of the liquid of 60 to 70 OC;
warm water (or solution) implies a temperature of the liquid of 40 to 50 OC;
diluted 1 : 1, 1 : 2, 1 : 5, etc. means that
the first figure gives the number of parts by volume of
concentrated acid or some other solution, and
the second figure gives the number of parts by volume
of water.
1.6 Indications as to the concentration of solutions show the quantity of solute (in grammes) in
the corresponding volume of the solvent.
1.7 The following symbols and abbreviations are used:
cm centimetre
d relative density
g gramme
g/l grammes per litre
ml millilitre
mm millimetre
PFA pure for analysis
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I
IS0 / R 319 - 1963 (E)
II. BISMUTHATE METHOD
2. PRINCIPLE OF METHOD
The determination of total manganese in manganese ore by the bismuthate method is based on
the oxidization of divalent manganese with sodium bismuthate in a nitric acid solution to
septivalency, with a subsequent reduction of manganese acid (HMn04) by a standard solution of
ferrous ammonium sulphate, and titration of the excess with a standard solution of potassium
permanganate.
It is essential that the oxidization should be carried out in nitric acid diluted 1 : 3, devoid of free
oxides of nitrogen. The concentration of manganese should not exceed 0.10 g per 250 ml of the
solution.
3. REAGENTS REQUIRED
.
3.1 Nitric acid, PFA, diluted 1 : 3.
3.2 Nitric acid, PFA, diluted 3 : 97, free from oxides of nitrogen (the removal of the oxides
or air through the nitric acid (d 1.40)
of nitrogen is effected by passing a current of oxygen
until there is a complete decolorization of the latter),
3.3 Sulphuric acid, PFA (d 1.84).
3.4 Sulphuric acid, PFA, diluted 1 : 9.
3.5 Hydrofluoric acid, PFA (40 per cent).
3.6 Sodium carbonate, anhydrous, PFA.
3.7 Sodium oxalate, anhydrous, precipitated in the presence of alcohol, PFA.
3.8 Sodium nitrite (NaNO,), PFA, solution (50 di).
3.9 Sodium bismuthate. The reagent should contain not less than 70 to 78 per cent of active
oxygen, as calculated for NaBiO,, or more than 0.002 per cent of chlorine ions, or more
than 0.001 per cent of manganese.
3.10 Ferrous ammonium sulphate (Fe(",), (SO,), .6H,O). 90 g of ferrous ammonium sulphate,
PFA, are dissolved in 1 litre of sulphuric acid, diluted 5 : 95.
3.11 Hydrogen peroxide, PFA, 30 per cent (perhydrol).
3.12 Standardsolution of potassium permanganate, 0.25 N. 7.9 g of potassium permanganate, PFA,
are dissolved in 1 litre of distilled water. The solution thus obtained is allowed to stand for
6 days and then it is siphoned off or filtered through a layer of glass wool and ignited asbestos
into a dark glass flask without disturbing any precipitate of manganese dioxide. The solution
contained in the flask should be protected from dust and gases, and kept in a cool place. The
solution should not be standardized earlier than the day foilowing filtration.
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IS0 / R 319 - 1963 (E)
4. STANDARDIZATION OF POTASSIUM PERMANGANATE SOLUTION (THEORETICAL TITRE)
4.1 Against sodium oxalate
4.1.1
Weigh 0.25 to 0.5 g of sodium oxalate, dried to constant weight at a temperature of
110 to 120 OC, into a flask of 500 ml capacity. Add to it 250 ml of sulphuric acid, diluted
1 : 9, heat the solution to a temperature of 70 to 80 OC and then titrate with the potassium
permanganate solution until a permanent pink colour is reached.
4.1.2 The titre of the potassium permanganate solution is found from the following formula:
G x 0.16396
T=
V
where
T = titre of potassium permanganate solution, expressed in grammes of man-
ganese;
G = mass of sodium oxalate, in grammes;
0.1639 6 = conversion factor for the titre of potassium permanganate solution, expressed
as sodium oxalate, to the titre of manganese;
V = number of millilitres of potassium permanganate solution used for titrating
the test sample of sodium oxalate.
4.1.3 The titre of the potassium permanganate solution is established with not less than three
test samples of sodium oxalate, the mean of three closely coinciding results being taken
as the final result.
4.1.4 It is advisable to check periodically the titre of the potassium permanganate solution
by means of test samples of potassium permanganate, PFA (0.25 to 0.3 g), passing
them through all the stages of the analysis.
5. PROCEDURE
5.1 Weigh 0.2 g of manganese ore into a 100 ml beaker, cover it with a watch-glass, and dissolve
by heating in 50 ml of nitric acid, diluted 1 : 3, carefully adding, drop by drop, 30 per cent
hydrogen peroxide, until the attack is complete.
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lÇO/ R 319 - 1963 (E)
Filter the solution obtained through a medium filter into a 750 ml conical flask; wash the
1 : 3, place it in a platinum crucible, and ignite.
filter several times with nitric acid, diluted
Cool, add a few drops of water, 2 to 3 drops of sulphuric acid (d 1.84) and 2 to 3 ml of
hydrofluoric acid, and evaporate to dryness. Heat the dry residue, and fuse it with 2 to 3 g
of sodium carbonate. Extract the fusion in nitric acid, diluted 1 : 3, and add the solution to
the original filtrate.
5.2 To maintain the required degree of acidity in the resultant combined solution, add nitric
acid, diluted 1 : 3, up to a volume of 250 ml.
5.3 In order to destroy organic matter and to oxidize other reducers, carefully add to the solution,
which has been heated to boiling, 1 g of sodium bismuthate, in small portions. If, during
boiling, the pink colour of manganic acid disappears or the residue of manganese dioxide
dissolves, it is necessary to add a further quantity of sodium bismuthate.
5.4 The formation of a permanent precipitate of manganese dioxide indicates complete oxidiza-
tion of the organic and other matter. Whilst still boiling, add, drop by drop, from a pipette,
a solution of sodium nitrite (50 g/1) until complete solution of the precipitate of manganese
dioxide. Then boil the clear solution for 15 to 25 min until the nitric oxides are driven off.
5.5 Should the nitric oxides not be driven off, the subsequent oxidization of the divalent man-
ganese with sodium bismuthate will not follow quantitatively.
If, as a result of boiling, the volume of the solution is decreased, make up to 250 ml with
distilled water.
5.6 Cool the solution to a temperature of 15 to 20 OC, add 6 to 8 g of sodium bismuthate, and
stir vigorously for 2 m
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