SIST EN ISO 20565-2:2009

Chemical analysis of chrome-bearing refractory products and chrome-bearing raw materials (alternative to the X-ray fluorescence method) - Part 2: Wet chemical analysis (ISO 20565-2:2008)

This part of EN 955, describes methods for chemical analysis of chrome ores, chrome refractories and magnesia-chrome refractories, using wet methods. The methods are not applicable to materials which contain phosphates.

Chemische Analyse von chromhaltigen feuerfesten Erzeugnissen und chromhaltigen Rohstoffen (Alternative zum Röntgenfluoreszenzverfahren) - Teil 2: Nasschemische Verfahren (ISO 20565-2:2008)

Diese Internationale Norm legt chemische Analysenverfahren für chromhaltige feuerfeste Erzeugnisse und Rohstoffe fest, die für die in Tabelle 1 angegebenen Bereiche anwendbar sind.
Tabelle 1  Bereich für die Bestimmung
Bestandteil   Bereich   Bestandteil   Bereich
   Massen¬anteil in Prozent      Massen¬anteil in Prozent
SiO2   0,5 bis 10   MnO   15 bis 85
Al2O3   2 bis 30   Na2O   0,01 bis 1
Fe2O3   0,5 bis 25   K2O   0,01 bis 1
TiO2   0,01 bis 1   Cr2O3   2 bis 60
MnO   0,01 bis 1   ZrO2   0,01 bis 0,5
CaO   0,01 bis 3   P2O5   0,01 bis 5
ANMERKUNG   Diese Werte werden behandelt, nachdem der Glühverlust bestimmt wurde.
Diese Norm enthält Festlegungen für folgende Analysen:
a)   Glühverlust (LOI);
b)   Silicium(IV) oxid (SiO2);
c)   Aluminiumoxid (Al2O3);
d)   Eisen(III) oxid (Gesamteisengehalt berechnet als Fe2O3);
e)   Titan(IV) oxid (TiO2);
f)   Mangan(II) oxid (MnO);
g)   Calciumoxid (CaO);
h)   Magnesiumoxid (MgO);
i)   Natriumoxid (Na2O);
j)   Kaliumoxid (K2O);
k)   Chrom(III) oxid (Cr2O3)
l)   Zirkoniumoxid (ZrO2);
m)   Phosphor(V) oxid (P2O5);
n)   Bor(III) oxid (B2O3).

Analyse chimique des produits réfractaires contenant du chrome et des matériaux bruts contenant du chrome (méthode alternative a la méthode par fluorescence de rayons X) - Partie 2: Méthodes d'analyse chimique par voie humide (ISO 20565-2:2008)

L'ISO 20565-2:2008 spécifie des méthodes traditionnelles («par voie humide») pour l'analyse chimique des produits réfractaires contenant du chrome et des matières premières contenant du chrome.

Kemijska analiza kromovih ognjevzdržnih izdelkov in kromovih surovin (alternativa rentgenski fluorescenčni metodi) - 2. del: Mokra kemijska analiza (ISO 20565-2:2008)

General Information

• Status: Published
• Public Enquiry End Date: 30-Oct-2008
• Publication Date: 18-Feb-2009
• ICS: 71.040.40 - Chemical analysis
• ICS: 81.080 - Refractories
• Technical Committee: IKER - Ceramics
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 09-Jan-2009
• Due Date: 16-Mar-2009
• Completion Date: 19-Feb-2009
• Ref Project: EN ISO 20565-2:2008 - Chemical analysis of chrome-bearing refractory products and chrome-bearing raw materials (alternative to the X-ray fluorescence method) - Part 2: Wet chemical analysis (ISO 20565-2:2008)

Standards Content (Sample)

SLOVENSKI STANDARD
SIST EN ISO 20565-2:2009
01-marec-2009
.HPLMVNDDQDOL]DNURPRYLKRJQMHY]GUåQLKL]GHONRYLQNURPRYLKVXURYLQ
DOWHUQDWLYDUHQWJHQVNLIOXRUHVFHQþQLPHWRGLGHO0RNUDNHPLMVNDDQDOL]D,62

Chemical analysis of chrome-bearing refractory products and chrome-bearing raw
materials (alternative to the X-ray fluorescence method) - Part 2: Wet chemical analysis
(ISO 20565-2:2008)
Chemische Analyse von chromhaltigen feuerfesten Erzeugnissen und chromhaltigen
Rohstoffen (Alternative zum Röntgenfluoreszenzverfahren) - Teil 2: Nasschemische
Verfahren (ISO 20565-2:2008)
Analyse chimique des produits réfractaires contenant du chrome et des matériaux bruts
contenant du chrome (méthode alternative a la méthode par fluorescence de rayons X) -
Partie 2: Méthodes d'analyse chimique par voie humide (ISO 20565-2:2008)
Ta slovenski standard je istoveten z: EN ISO 20565-2:2008
ICS:
71.040.40 Kemijska analiza Chemical analysis
81.080 Ognjevzdržni materiali Refractories
SIST EN ISO 20565-2:2009 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN ISO 20565-2:2009

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SIST EN ISO 20565-2:2009
EUROPEAN STANDARD
EN ISO 20565-2
NORME EUROPÉENNE
EUROPÄISCHE NORM
December 2008
ICS 81.080

English Version
Chemical analysis of chrome-bearing refractory products and
chrome-bearing raw materials (alternative to the X-ray
fluorescence method) - Part 2: Wet chemical analysis (ISO
20565-2:2008)
Analyse chimique des produits réfractaires contenant du Chemische Analyse von chromhaltigen feuerfesten
chrome et des matières premières contenant du chrome Erzeugnissen und chromhaltigen Rohstoffen (Alternative
(méthode alternative à la méthode par fluorescence de zum Röntgenfluoreszenzverfahren) - Teil 2:
rayons X) - Partie 2: Méthodes d'analyse chimique par voie Nasschemische Verfahren (ISO 20565-2:2008)
humide (ISO 20565-2:2008)
This European Standard was approved by CEN on 8 November 2008.
CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European
Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national
standards may be obtained on application to the CEN Management Centre or to any CEN member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CEN member into its own language and notified to the CEN Management Centre has the same status as the
official versions.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland,
France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,
Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36  B-1050 Brussels
© 2008 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 20565-2:2008: E
worldwide for CEN national Members.

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SIST EN ISO 20565-2:2009
EN ISO 20565-2:2008 (E)
Contents Page
Foreword .3

2

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SIST EN ISO 20565-2:2009
EN ISO 20565-2:2008 (E)
Foreword
This document (EN ISO 20565-2:2008) has been prepared by Technical Committee ISO/TC 33 "Refractories"
in collaboration with Technical Committee CEN/TC 187 “Refractory products and materials” the secretariat of
which is held by BSI.
This European Standard shall be given the status of a national standard, either by publication of an identical
text or by endorsement, at the latest by June 2009, and conflicting national standards shall be withdrawn at
the latest by June 2009.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent rights.
According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following
countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Cyprus, Czech
Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain,
Sweden, Switzerland and the United Kingdom.
Endorsement notice
The text of ISO 20565-2:2008 has been approved by CEN as a EN ISO 20565-2:2008 without any
modification.

3

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SIST EN ISO 20565-2:2009

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SIST EN ISO 20565-2:2009

INTERNATIONAL ISO
STANDARD 20565-2
First edition
2008-12-01


Chemical analysis of chrome-bearing
refractory products and chrome-bearing
raw materials (alternative to the X-ray
fluorescence method) —
Part 2:
Wet chemical analysis
Analyse chimique des produits réfractaires contenant du chrome et des
matières premières contenant du chrome (méthode alternative à la
méthode par fluorescence de rayons X) —
Partie 2: Méthodes d'analyse chimique par voie humide




Reference number
ISO 20565-2:2008(E)
©
ISO 2008

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SIST EN ISO 20565-2:2009
ISO 20565-2:2008(E)
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All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means,
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Published in Switzerland

ii © ISO 2008 – All rights reserved

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SIST EN ISO 20565-2:2009
ISO 20565-2:2008(E)
Contents Page
Foreword. iv
1 Scope .1
2 Normative references .2
3 Determination of silicon(IV) oxide.2
4 Determination of aluminium oxide.5
5 Determination of total iron as iron(III) oxide .8
6 Determination of titanium(IV) oxide.11
7 Determination of manganese(II) oxide .13
8 Determination of calcium oxide .14
9 Determination of magnesium oxide.15
10 Determination of sodium oxide by flame photometry .18
11 Determination of potassium oxide by flame spectrophotometry .20
12 Determination of chromium(III) oxide.21
13 Determination of zirconium oxide by xylenol orange absorption spectroscopy.24
14 Determination of phosphorus(V) oxide by molybdenum blue method.25
15 Test report .27




© ISO 2008 – All rights reserved iii

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SIST EN ISO 20565-2:2009
ISO 20565-2:2008(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.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
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.
ISO 20565-2 was prepared by Technical Committee ISO/TC 33, Refractories, in collaboration with Technical
Committee CEN/TC 187, Refractory products and materials.
ISO 20565 consists of the following parts, under the general title Chemical analysis of chrome-bearing
refractory products and chrome-bearing raw materials (alternative to the X-ray fluorescence method):
⎯ Part 1: Apparatus, reagents, dissolution and determination of gravimetric silica
⎯ Part 2: Wet chemical analysis
⎯ Part 3: Flame atomic absorption spectrometry (FAAS) and inductively coupled plasma atomic emission
spectrometry (ICP-AES)

iv © ISO 2008 – All rights reserved

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SIST EN ISO 20565-2:2009
INTERNATIONAL STANDARD ISO 20565-2:2008(E)

Chemical analysis of chrome-bearing refractory products and
chrome-bearing raw materials (alternative to the X-ray
fluorescence method) —
Part 2:
Wet chemical analysis
1 Scope
This part of ISO 20565 specifies traditional (“wet process”) methods for the chemical analysis of chrome-
bearing refractory products and raw materials.
It is applicable to components within the ranges of determination given in Table 1.
Table 1 — Range of determination (% by mass)
Component Range
SiO
0,5 to 10
2
Al O
2 to 30
2 3
Fe O
0,5 to 25
2 3
TiO
0,01 to 1
2
MnO 0,01 to 1
CaO 0,01 to 3
MgO 15 to 85
Na O
0,01 to 1
2
K O
0,01 to 1
2
Cr O
2 to 60
2 3
ZrO
0,01 to 0,5
2
P O
0,01 to 5
2 5
LOI
−0,5 to 5
NOTE These values are after the loss on ignition (LOI) has been
taken into account.
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SIST EN ISO 20565-2:2009
ISO 20565-2:2008(E)
2 Normative references
The following referenced documents are indispensable for the application 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 20565-1:2008, Chemical analysis of chrome-bearing refractory products and chrome-bearing raw
materials (alternative to the X-ray fluorescence method) — Part 1: Apparatus, reagents, dissolution and
determination of gravimetric silica
ISO 26845:2008, Chemical analysis of refractories — General requirements for wet chemical analysis, atomic
absorption spectrometry (AAS) and inductively compled plasma atomic emission spectromety (ICP-AES)
methods
3 Determination of silicon(IV) oxide
3.1 General
Determine the silicon(IV) oxide content using one of the following methods.
a) Combined use of the dehydration or the coagulation and molybdenum blue methods
This method is applied to samples consisting of more than 4 % by mass of silicon(IV) oxide.
b) Molybdenum blue method
This method is applied to samples consisting of less than 10 % by mass of silicon(IV) oxide.
3.2 Combined use of the coagulation and molybdenum blue methods
3.2.1 Principle
An aliquot portion of the stock solution (S1) (see ISO 20565-1), after pH adjustment, is treated with
ammonium molybdate and the silicomolybdate is reduced to yield molybdenum blue, the absorbance of which
is measured.
The sum of this residual silicon(IV) oxide in solution plus the mass of silicon(IV) oxide determined in
ISO 20565-1:2008, 9.2.2.3.3, gives the total silicon(IV) oxide content.
3.2.2 Procedure
This determination should be commenced with little delay after the stock solution (S1) is prepared, as
prolonged standing may allow polymerization of silica to occur leading to low results.
Transfer 10 ml of stock solution (S1) (see ISO 20565-1) to a 100 ml plastic beaker, add 2 ml of hydrofluoric
acid (1+9) and mix with a plastic rod. Allow to stand for 10 min and add 50 ml of boric acid solution. Add 2 ml
of ammonium molybdate solution while mixing at a temperature of 25 °C and allow to stand for 10 min. Add
5 ml of L (+)-tartaric acid solution while stirring and, after 1 min, add 2 ml of L (+)-ascorbic acid solution.
Transfer the solution to a 100 ml volumetric flask, dilute to the mark with water, mix and allow to stand for
60 min.
Measure the absorbance of the solution in a 10 mm cell at a wavelength of 650 nm against water as a
reference.
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SIST EN ISO 20565-2:2009
ISO 20565-2:2008(E)
3.2.3 Plotting calibration graph
Transfer 0 ml, 2 ml, 4 ml, 6 ml, 8 ml and 10 ml aliquot portions of diluted standard silicon(IV) oxide solution
(0 mg to 0,4 mg as silicon(IV) oxide) to separate 100 ml plastic beakers and add to each 10 ml of blank
solution (B1) (see ISO 20565-1). Treat these solutions and measure the absorbance as given in 3.2.2, and
plot the absorbances against the amounts of silicon(IV) oxide. Prepare the calibration graph by adjusting the
curve so that it passes through the point of origin.
3.2.4 Blank test
Using blank solution (B1), carry out the procedure given in 3.2.2.
3.2.5 Calculation
Calculate the mass fraction of silicon(IV) oxide, w , expressed as a percentage, using Equation (1) with
SiO
2
the absorbances obtained in 3.2.2 and 3.2.4 and the calibration in 3.2.3.
500
mm−+m−m×
()()
12 s b
10
w=×100 (1)
SiO
2
m
where
m is the mass from ISO 20565-1, in grams (g);
1
m is the mass from ISO 20565-1, in grams (g);
2
m is the mass of silicon(IV) oxide in the aliquot portion of stock solution (S1) as applicable, in grams (g);
s
m is the mass of silicon(IV) oxide in the aliquot portion of blank solution (B1) as applicable, in grams (g);
b
m is the mass of the test portion from ISO 20565-1, in grams (g).
3.3 Molybdenum blue method
3.3.1 Principle
An aliquot portion of the stock solution (S′1) (see ISO 20565-1), after pH adjustment, is treated with
ammonium molybdate and the silicomolybdate is reduced to yield molybdenum blue, the absorbance of which
is measured.
3.3.2 Procedure
Transfer precisely an aliquot portion of stock solution (S′1) (to two 100 ml plastic beakers and add to each an
aliquot portion of blank solution obtained from 3.3.3. Add to each beaker 2 ml of hydrofluoric acid (1+9), mix
with a plastic rod and allow to stand for 10 min. Add 50 ml of boric acid solution, dilute to 80 ml with water.
Add 5 ml of ammonium molybdate solution while mixing at a temperature of 25 °C and allow to stand for
10 min. Add 5 ml of L (+)-tartaric acid solution while stirring and, after 1 min, add 10 ml of L (+)-ascorbic acid
solution. Transfer each solution to a 200 ml volumetric flask, dilute to the mark with water and mix. Allow to
stand for 60 min and measure the absorbance of the solutions in a 10 mm cell at a wavelength of 650 nm
against water as a reference. Take the mean of the two measurements.
NOTE Aliquot volumes of stock solution and blank solution (B′1) are shown in Table 2, corresponding to the content
of silicon(IV) oxide in the sample.
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SIST EN ISO 20565-2:2009
ISO 20565-2:2008(E)
When the difference of the two absorbance measurements is greater than 0,005, repeat the procedure in
3.3.2. When measurements of the same sample with around 1,0 absorbance are repeated, it is necessary for
the spectrophotometer to show the differences within 0,002.
Table 2 — Aliquot volumes of stock and blank solutions
Mass fraction Aliquot portion Aliquot portion
of silicon(IV) oxide
of stock solution (S′1) of blank solution (B′1)
%
ml ml
< 2 20 0
2 to 4 10 10
4 to 10 5 15

3.3.3 Blank test
Using the blank solution (B′1) (see ISO 20565-1), follow the procedure given in 3.3.2. The volume of the
aliquot portion of blank solution is the same as that for the corresponding stock solution.
3.3.4 Plotting of calibration graph
Transfer 0 ml, 5 ml, 10 ml, 15 ml, 20 ml and 25 ml aliquot portions of diluted standard silicon(IV) oxide solution
[0 mg to 1 mg as silicon(IV) oxide] to separate 100 ml plastic beakers and add to each 20 ml of blank solution
(B′1) (see ISO 20565-1). Treat these solutions and measure the absorbance in accordance with the
procedure for addition of hydrofluoric acid (1+9) in 3.3.2. Plot the absorbance against the amounts of
silicon(IV) oxide and prepare the calibration graph by adjusting the curve so that it passes through the point of
origin.
3.3.5 Calculation
Calculate the mass fraction of silicon(IV) oxide, w , expressed as a percentage, using Equation (2) with
SiO
2
the amount of silicon(IV) oxide derived from the absorbance measurements obtained in 3.3.2 and 3.3.3 and
the calibration in 3.3.4.
mm− 250
sb
w=××100 (2)
SiO
2
mV
where
m is the mass of silicon(IV) oxide in the aliquot portion of stock solution (S′1), in grams (g);
s
m is the mass of silicon(IV) oxide in the aliquot portion of blank solution (B′1), in grams (g);
b
V is the aliquot volume of stock solution (S′1), in millilitres (ml);
m is the mass of the test portion, in grams (g).
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SIST EN ISO 20565-2:2009
ISO 20565-2:2008(E)
4 Determination of aluminium oxide
4.1 General
Determine the aluminium oxide content using one of the following methods:
a) cation-exchange separation — CyDTA-zinc back-titrimetric method (see 4.2);
b) cupferron extraction separation — CyDTA-zinc back-titrimetric method (see 4.3).
4.2 Cation-exchange separation — (1,2-Cyclohexylenenitrilo)tetraacetic acid zinc [CyDTA-
zinc] back-titrimetric method
4.2.1 Principle
An aliquot portion of stock solution (SE-a) is transferred. Excess CyDTA solution is added to it. A chelate
compound of aluminium CyDTA is formed by adjusting the pH with ammonia solution. The pH is further
adjusted by the addition of hexamethylenetetramine. The amount of remaining CyDTA is determined by back-
titration with zinc standard volumetric solution using xylenol orange as an indicator. The content of aluminium
oxide is calculated by adjusting the content of titanium(IV) oxide.
4.2.2 Procedure
4.2.2.1 Transfer precisely an aliquot portion of stock solution (SE-a) (see ISO 20565-1 and the following
paragraph) to a 300 ml beaker. Add an amount of 0,01 mol/l CyDTA solution, in accordance with Table 4, and
dilute to 100 ml with water. Add 1 g of hexamethylenetetramine and a drop of methyl orange solution as an
indicator. Drop in ammonia water (1+1) and ammonia solution (1+9) of up to pH 3 until it indicates a slightly
orange colour (see the paragraph directly below Table 3). Allow to stand for 5 min.
In Table 3, the aliquot volume of stock solution (SE-a) is shown. It depends on the volume of the aliquot
portion of stock solution (S5) used in ISO 20565-1.
Table 3 — Aliquot volume of stock solution (SE-a)
Aliquot volume of stock solution (S5) Aliquot volume of stock solution (SE-a)
ml ml
100 40
50 80

If ammonia solution is added to excess, add hydrochloric acid (1+1) until the colour is changed to red, then
adjust in the same manner.
NOTE The volume of 0,01 mol/l of CyDTA solution added depends on the mass fraction of aluminium oxide as
shown in Table 4.
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SIST EN ISO 20565-2:2009
ISO 20565-2:2008(E)
Table 4 — Aliquot volume of 0,01 mol/l CyDTA solution
Mass fraction of aluminium oxide Volume of 0,01 mol/l CyDTA solution
% ml
< 5 10
5 to 10 20
10 to 15 30
15 to 20 40
20 to 30 50

4.2.2.2 Add 5 g of hexamethylenetetramine of pH 5,5 to 5,8, add 4 or 5 drops of xylenol orange solution
as an indicator and titrate with 0,01 mol/l zinc standard volumetric solution. Titrate while mixing gently and
when the colour changes from yellow to the first appearance of a permanent reddish colour, consider this as
the end point.
4.2.3 Blank test
Using the blank solution (BE-a) (see ISO 20565-1), follow the procedure given in 4.2.2. The volumes of the
aliquot portion of blank solution (BE-a) and 0,01 mol/l CyDTA solution are the same as those for the
corresponding stock solution (SE-a).
4.2.4 Calculation
Calculate the mass fraction of aluminium oxide, w , expressed as a percentage, using Equation (3).
Al O
23
(VV−×) F× 0,000 509 8 100 250
21
ww=×××100−× 0,638 (3)
Al O TiO
23 2
m 40 100
where
V is the volume of 0,01 mol/l zinc standard volumetric solution in 4.2.3, in millilitres (ml);
1
V is the volume of 0,01 mol/l zinc standard volumetric solution in 4.2.2.2, in millilitres (ml);
2
F is the factor of 0,01 mol/l zinc standard volumetric solution;
m is the mass of the test portion (see ISO 20565-1), in grams (g);
w is the mass fraction of titanium(IV) oxide determined in 6.2.5 or 6.3.5, expressed as a percentage.
TiO
2
4.3 Cupferron extraction separation — (1,2-Cyclohexylenenitrilo)tetraacetic acid zinc
[CyDTA-zinc] back-titrimetric method
4.3.1 Principle
An aliquot portion of the stock solution (S6) (see ISO 20565-1) is cleaned up using first diethyldicarbonate and
then cupferron in a separating funnel. To the resulting solution an excess of CyDTA is added, then back-
titrated with a standard zinc solution.
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SIST EN ISO 20565-2:2009
ISO 20565-2:2008(E)
4.3.2 Procedure
4.3.2.1 Transfer 100 ml of the stock solution (S6) to the 500 ml separating funnel. Add the ammonia solution
drop by drop until the solution is faintly alkaline to bromophenol blue. Re-acidify with dilute hydrochloric acid
(1+3) and add an extra 4 ml. Add 20 ml of chloroform and 10 ml of sodium diethyldithiocarbamate solution.
Stopper the funnel and shake vigorously. Release the pressure in the funnel by carefully removing the stopper
and rinse the stopper and neck of the funnel with water. Allow the layers to separate and withdraw the
chloroform layer.
If an emulsion has formed, it will be necessary to add a few drops of hydrochloric acid and reshake.
Add 10 ml portions of chloroform and 5 ml portions of the sodium diethyldithiocarbamate and repeat the
extraction until a coloured precipitate (brown or pink) is no longer formed. Wash the aqueous phase with 20 ml
of chloroform to remove iron and manganese.
4.3.2.2 Add 25 ml of the hydrochloric acid, concentrated, 36 % by mass, followed by 2 ml to 3 ml of cupferron
solution and 20 ml of chloroform. Stopper the funnel and shake vigorously. Remove the stopper and rinse the
stopper and neck of the funnel with water. Allow the layers to separate and withdraw the chloroform layer.
Repeat the extraction with three 10 ml portions of chloroform to remove traces of cupferron and sodium
diethyldithiocarbamate. Run the aqueous phase from the separating funnel to a 1 l conical flask. Add a few
drops of bromophenol blue indicator, followed by the ammonia solution until the solution is just alkaline. Re-
acidify quickly with the concentrated hydrochloric acid, add an extra 5 to 6 drops and cool the flask in running
water.
4.3.2.3 Ensure that the solution is cold. Add CyDTA standard solution (0,05 M approximately) to produce an
excess of a few millilitres over the expected amount (1 ml = 1,275 % Al O ). Add ammonium acetate buffer
2 3
solution until the indicator turns blue, followed by an extra 15 ml. Add a volume of ethanol equal to the total
volume of the solution, then add 20 ml of the hydroxyammonium chloride solution and 1 ml to 2 ml of the
dithizone indicator. Titrate with zinc standard solution (0,05 M) from green to the first appearance of a
permanent pink colour.
NOTE The end point is often improved by the addition of a little naphthol green solution to eliminate any early
formation of pink colour that might have formed in the solution on the addition of the indicator.
4.3.3 Calculation
Calculate the mass fraction of aluminium oxide, w , expressed as a percentage, using Equation (4).
Al O
23
(VF×−V×F )× 0,001 019 6 250
11 2 2
w=××100 (4)
Al O
23
m 100
where
V is the volume of the 0,05 mol/l CyDTA standard solution in 4.3.2.3, in millilitres (ml);
1
F is the factor of the 0,05 mol/l CyDTA standard solution;
1
V is the volume of 0,05 mol/l zinc standard solution used in the back-titration in 4.3.2.3,
2
in millilitres (ml);
F is the factor of 0,05 mol/l zinc standard solution;
2
m is the mass of the test portion (see ISO 20565-1), in grams (g).
© ISO 2008 – All rights reserved 7

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SIST EN ISO 20565-2:2009
ISO 20565-2:2008(E)
5 Determination of total iron as iron(III) oxide
5.1 General
Determine the iron(III) oxide content using one of the following methods.
a) 1,10-Phenanthroline absorption method using stock solution (S6) or (S′6) (see ISO 20565-1)
This method is applied to samples consisting of less than 15 % by mass of iron(III) oxide (see 5.2).
b) 1,10-Phenanthroline absorption method using stock solution (SE-b) (see ISO 20565-1)
This method is applied to samples consisting of less than 15 % by mass of iron(III) oxide (see 5.3).
c) CyDTA-Zinc back-titrimetric method
This method is applied to samples consisting of 10 % by mass or more of iron(III) oxide (see 5.4).
5.2 1,10-Phenanthroline absorption method using stock solution (S6) or (S′6)
5.2.1 Principle
An aliquot portion of the stock solution (S6) (see ISO 20565-1) is reduced with hydroxylamine chloride to
iron(II) oxide, coloured with 1,10 ortho-phenanthroline and its absorbance measured at 510 nm.
5.2.2 Procedure
5.2.2.1 Dilute 25,0 ml of the stock solution (S6) (see ISO 20565-1) with water to 500 ml in a volumetric flask
and mix. Transfer 25 ml of this diluted solution to a 100 ml volumetric flask and add 2 ml of the
hydroxyammonium chloride solution followed by 5 ml of the phenanthroline solution. Add the ammonium
acetate solution until a pink colour forms, then add an extra 2 ml. Allow to stand for 15 min, dilute the solution
with water to 100 ml and mix. Use a spectrophotometer to measure the optical density of the solution against
water in 10 mm cells at 510 nm.
NOTE The use of a filter-type absorptiometer is not appropriate to this test.
5.2.2.2 Add ammonium acetate solution to stabilize the colour. Ensure that the colour is stable from 15 min to
75 min. Determine the iron(II) oxide content of the solution by reference to a calibration graph.
NOTE The dilution of the “stock” solution quoted will cover the range from 0 % to 20 % Fe O by mass. For iron
2 3
mass fractions considerably below 20 % Fe O , a decreased dilution of the “stock” solution needs to be made. The aliquot
2 3
portion of the solution should not be diluted once the colour has developed.
5.2.3 Blank test
Using blank solution (B6) (see ISO 20565-1), carry out the procedure given in 5.2.2. The volu
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