|
STANDARD 468811
First edition
1992-12-15
Iran ores - Determination of aluminium
content -
Part 1:
Flame atomic absorption spectrometric method
Minerais de fer - Dosage de /‘aluminium -
Partie 1: Methode par spectrometrie d’absorption atomique dans la
flamme
----
---~.
----
--
Reference number
~-- -.
--- .^----~___ ISO 4688-1: 1992( E)
-.--- -.-. ----___-__I
---------------------- Page: 1 ----------------------
ISO 4688-1:1992(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. Esch 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, govern-
mental 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.
Draft International Standards adopted by the technical committees are
circulated to the member bodies for voting. Publication as an Inter-
national Standard requires approval by at least 75 % of the member
bodies casting a vote.
International Standard ISO 4688-1 was prepared by Technical Committee
ISO/TC 102, Iran ores, Sub-Committee SC 2, Chemical analysis.
This part of ISO 4688 cancels and replaces ISO 46883990, of which it
constitutes a technical revision.
ISO 4688 consists of the following patt, under the general title Iran ores
- Determination of aluminium content:
- Part 1: Flame afomic absorpfion specfromefric method
Additional Parts will be published later.
Annex A forms an integral part of this part of ISO 4688. Annexes B and
C are for information only.
0 ISO 1992
All rights reserved. No patt of this publication may be reproduced or utilized in any ferm
or by any means, electronie or mechanical, including photocopying and microfilm, without
Permission in writing from the publisher.
International Organization for Standardization
Case Postale 56 l CH-121 1 Geneve 20 l Switzerland
Printed in Switzerland
ii
---------------------- Page: 2 ----------------------
---~
INTERNATIONAL STANDARD ISO 4688=1:1992(E)
- Determination of aluminium content -
Iron ores
Part 1:
Flame atomic absorption spectrometric method
1 Scope 3 Principle
This part of ISO 4688 specifies a flame atomic ab- Decomposition of the test Portion by treatment with
hydrochloric acid and a small amount of nitric acid.
sorption spectrometric method for the determination
of the aluminium content of iron ores.
Evaporation to dehydrate silica, followed by dilution
This method is applicable to aluminium contents and filtration.
between 0,l % (m/m) and 5,0 % (m/m) in natura1
Ignition of the residue and removal of silica by
iron ores, iron ore concentrates and agglomerates,
evaporation with hydrofluoric and sulfuric acids.
including Sinter products.
Fusion with sodium carbonate and dissolution of the
cooled melt in the filtrate.
2 Normative references
Aspiration of the Solution obtained into the flame of
an atomic absorption spectrometer using a
The following Standards contain provisions which,
dinitrogen Oxide-acetylene burner.
through reference in this text, constitute provisions
of this part of ISO 4688. At the time of publication,
Comparison of the absorbance values obtained for
the editions indicated were valid. All Standards are
aluminium with those obtained from the calibration
subject to revision, and Parties to agreements based
solutions.
on this part of ISO 4688 are encouraged to investi-
gate the possibility of applying the most recent edi-
tions of the Standards indicated below. Members of
4 Reagents
IEC and ISO maintain registers of currently valid In-
ternational Standards.
During the analysis, Lose only reagents of recognized
analytical grade and only distilled water or water of
ISO 648:1977, Laborafory glassware - One-mark
equivalent purity.
pipettes.
4.1 Sodium carbonate (Na,CO,), anhydrous.
ISO 1042:1983, Laboratory glassware - One-mark
volumetric flasks.
4.2 Hydrochlorit acid, p 1,19 g/ml.
ISO 3081:1986, Iran ores - Increment sampling -
Manual method.
4.3 Nitrit acid, p 1,4 g/ml.
ISO 3082:1987, Iran ores - Increment sampling and
Sample preparation - Mechariical method.
4.4 Hydrochlorit acid, p 1,19 g/ml, diluted 1 + 9.
ISO 3083:1986, Iran ores - Reparation of samples
4.5 Hydrofluoric acid, p IJ3 g/ml, 40 % (m/m), or
- Manual method.
p 1,185 g/ml, 48 % (mlm).
ISO 7764:1985, Iran ores - Reparation of predried
4.6 Sulfuric acid, p 1,84 g/ml, diluted 1 + 1.
test samples for Chemical analysis.
---------------------- Page: 3 ----------------------
ISO 4688=1:1992(E)
4.7 Background Solution. a) Minimum sensitivity - the absorbance of the
most concentrated aluminium caiibration soi-
Dissoive IO g of high purity iron [minimum purity
ution (4.9) shali be at least 0,3.
99,9 % 0,002 % (m/m), in 50 mi of hydrochioric acid (4.2)
b) Graph iinearity - the slope of the caiibration
and oxidize by adding nitric acid (4.3) drop by drop.
graph covering the top 20 % of the concentration
range (expressed as a Change in absorbance)
Evaporate untii a syrupy consistency is obtained.
shall not be iess than 0,7 of the vaiue of the siope
Add 20 mi of hydrochioric acid (4.2) and diiute to
for the bottom 20 % of the concentration range
200 mi with water. Dissoive 17 g of sodium
determined in the Same way.
carbonate (4.1) in water and add it to the iron soi-
ution. Transfer the Solution to a 1 000 ml one-mark
Minimum stabiiity - the Standard deviation of the
c)
voiumetric fiask and dilute to voiume with water.
absorbance of the most concentrated calibration
Solution and that of the Zero calibration Solution,
4.8 Aluminium Standard solution, 500 pg Ai/mi. each being calcuiated from a sufficient number
of repetitive measurements, shaii be less than
Dissoive 0,500 0 g of high purity aluminium
1,5 % and 0,5 % respectiveiy of the mean vaiue
99,9 % (m/m)] in 25 mi of
[minimum purity
of the absorbance of the most concentrated cali-
hydrochloric acid (4.2). Cool, transfer to a 1 000 ml
bration Solution.
one-mark volumetric flask, diiute to voiume with
NOTES
water and mix.
1 The use of a strip-chart recorder and/or digital readout
4.9 Aluminium calibration solutions.
device is recommended to evaluate criteria a) b) and c)
and for all subsequent measurements.
Transfer 2,0 mi; 5,0 mi; IO,0 mi; 20,O mi; 40,O mi and
50,O mi portions of aluminium Standard Solution 2 Instrument Parameters may vary with each instru-
ment. The following Parameters were successfully used in
(4.8) to 200 mi voiumetric fiasks. Diiute to about
several laboratories and they tan be used as guidelines.
100 ml. Add 6 mi of hydrochioric acid (4.2) and
Solutions were aspirated into a dinitrogen Oxide-acetylene
60 mi of background Solution (4.7) to each fiask.
flame of a premix burner.
Prepare a Zero aluminium caiibration Solution by
transferring 60 mi of the background Solution to a
Aluminium hollow cathode lamp, mA 25
200 mi voiumetic flask, and add 6 mi of hydrochioric Wavelength, nm 396,2
13,8
Dinitrogen Oxide flow rate, I/min
acid (4.2). Diiute all the soiutions to 200 mi with wa-
Acetylene flow rate, I/min
676
ter and mix. (For an atomic absorption spectrometer
having high sensitivity, smailer portions of the stan-
In Systems where the values shown above for gas flow
dard Solution may be used.)
rates do not apply, the ratio of the gas flow rates may still
be a useful guideline.
5 Apparatus
6 Sampling and samples
Ordinary iaboratory apparatus, inciuding one-mark
pipettes and one-mark voiumetric fiasks compiying
with the specifications of ISO 648 and ISO 1042 re-
6.1 Laboratory Sample
spectiveiy, and
For analysis, use a iaboratory Sample of minus
100 pm particie size which has been taken in ac-
5.4 Platinum crucible, of capacity 30 mi.
cordante with ISO 3081 or ISO 3082 and prepared in
accordance with ISO 3082 or ISO 3083. In the case
5.2 Muffle furnace, capable of maintaining a tem-
of ores having significant contents of combined wa-
perature of approximateiy 1 100 “C .
ter or oxidizabie compounds, use a par-ticie size of
minus 160 Pm.
5.3 Atomic absorption spectrometer, equipped with
NOTE 3 A guideline on significant contents of combined
a dinitrogen Oxide-acetyiene burner.
water and oxidizable compounds is incorporated in
ISO 7764.
WARNING - Follow the manufacturer’s instructions
for igniting and extinguishing the dinitrogen oxide-
6.2 Reparation of predried test samples
acetylene flame to avoid possible explosion hazards.
Wear tinted safety glasses whenever the flame ls
Thoroughiy mix the iaboratory Sample and, taking
burning.
multiple increments, extract a test Sample in such a
tromete r used in this way that it is representative of the whoie contents
The atomi C absor ption spec
ai the foiiowi ng crite ria. of the Container. Dry the test Sample at
meth od sh i meet
---------------------- Page: 4 ----------------------
ISO 4688-1:1992(E)
105 “C + 2 “C, as specified in ISO 7764. (This is the boiling, until no further attack is apparent. Add 2 ml
predried test Sample.) of nitric acid (4.3) and digest for severai minutes.
Remove the watch-giass and evaporate the Solution
to dryness. Heat the saits on the hot-piate at 105 “C
7 Procedure
to 110 “C for 30 min. Add 5 mi of hydrochioric acid
(4.2), cover the beaker with a watch-giass, and warm
7.1 Number of determinations
for severai minutes. Add 50 mi of water, heat to
boiiing, wash the watch-giass and the Walls of the
Carry out the anaiysis at least in dupiicate in ac-
beaker, and fiiter the soiution through a medium-
cordante with annex A, independentiy, on one pre-
texture Paper into a 250 mi beaker. Carefuiiy remove
dried test Sample.
all adhering particies with a rubber-tipped rod or
moistened fiiter Paper. Wash three times with
NOTE 4 The expression “independently” means that the
hydrochioric acid (4.4), then with hot water untii the
second and any subsequent result is not affected by the
fiiter Paper is free of iron. Transfer the Paper and
previous result(s). For this particular analytical method,
residue to a piatinum crucibie (5.1). Evaporate the
this condition implies that the repetition of the procedure
fiitrate to about 100 mi and retain it.
is carried out either by the same Operator at a different
time or by a different Operator including, in either case,
appropriate recalibration.
7.4.2 Treatment of the residue
7.2 Test Portion
ignite the Paper and residue in the piatinum crucibie
(5.1) at a low temperature (500 “C to 800 “C). Cool,
Taking severai increments, weigh, to the nearest
moisten with a few drops of water, add 3 or 4 drops
0,000 2 g, approximateiy 1 g of the predried fest
of suifuric acid (4.6) and IO mi of hydrofluoric acid
Sample obtained in accordance with 6.2.
(4.5). Evaporate siowiy to expei siiica and then fume
to remove the excess suifuric acid. ignite at about
NOTE 5 The test Portion should be taken and weighed
700 “C. Add 1,O g of sodium carbonate (4.1) to the
quickly to avoid reabsorption of moisture.
residue (see note 7), cover the crucible, and fuse
over a burner or in a muffle furnace (5.2) untii a clear
7.3 Blank test and check test
meit is obtained (at about 1 100 “C for 15 min).
In each run, one blank test and one anaiysis of a
NOTE 7 If difficuities are experienced with the fusion,
certified reference material of the Same type of ore 2 g of sodium carbonate (4.1) may be used, with a doubled
volume of hydrochloric acid (4.2). In this case, prepare the
shaii be carried out in parallel with the anaiysis of
background Solution (4.7) with doubled. quantities of
the ore Sample(s) under the Same conditions. A
sodium carbonate and hydrochloric acid.
predried test Sample of the certified reference ma-
terial shaii be prepared as specified in 6.2.
7.4.3 Preparation of the test Solution
NOTE 6 The certified reference material should be of
the same type as the Sample to be analysed and the
Dissoive the cooied meit in the retained fiitrate (see
properties of the two materials should be sufficiently
7.4.1 ), then remove and wash the crucibie and cover
similar to ensure that in either case no significant changes
in the analy
...