© ISO 2017 Iron ores — Determination of sulfur content — Part 3 Combustion/infrared method Minerais de fer — Dosage du soufre — Partie 3 Méthode par combustion et infrarouge INTERNATIONAL STANDARD ISO[.]
INTERNATIONAL STANDARD ISO 4689-3 Third edition 2017-03 Iron ores — Determination of sulfur content — Part 3: Combustion/infrared method Minerais de fer — Dosage du soufre — Partie 3: Méthode par combustion et infrarouge Reference number ISO 4689-3:2017(E) © ISO 2017 ISO 4689-3 : 01 7(E) COPYRIGHT PROTECTED DOCUMENT © ISO 2017, Published in Switzerland All rights reserved Unless otherwise specified, no part o f this publication may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior written permission Permission can be requested from either ISO at the address below or ISO’s member body in the country o f the requester ISO copyright o ffice Ch de Blandonnet • CP 401 CH-1214 Vernier, Geneva, Switzerland Tel +41 22 749 01 11 Fax +41 22 749 09 47 copyright@iso.org www.iso.org ii © ISO 2017 – All rights reserved ISO 4689-3 : 01 7(E) Page Contents iv Introduction v Scope Normative references Terms and definitions Principle Reagents Apparatus Sampling and samples 7.2 Preparation of predried test samples Procedure 8.1 Number of determinations 8.2 Test portion 8.3 Blank test and check test 8.4 Determination 8.5 Preparation of calibration graph Expression of results 9.1 Calculation of sulfur content 9.2 General treatment of results f 9.2.3 Between-laboratories precision 9.2.4 Check for trueness f 10 Test report Foreword 7.1 Annex A Lab o rato ry s amp le 9.2 Rep eatab ility and p ermis s ib le to lerance 9.2 D eterminatio n o 9.2 C alculatio n o (normative) analytical res ult final res ult Flowsheet of the procedure for the acceptance of analytical values for 1 Annex B (informative) Derivation of repeatability and permissible tolerance equations Annex C (informative) Precision data obtained by international analytical trial Bibliography test samples © ISO 2017 – All rights reserved iii ISO 4689-3 : 01 7(E) Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies) The work o f 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 o f electrotechnical standardization The procedures used to develop this document and those intended for its further maintenance are described in the ISO/IEC Directives, Part In particular the different approval criteria needed for the di fferent types o f ISO documents should be noted This document was dra fted in accordance with the editorial rules of the ISO/IEC Directives, Part (see www.iso org/directives) Attention is drawn to the possibility that some o f the elements o f this document may be the subject o f patent rights ISO shall not be held responsible for identi fying any or all such patent rights Details o f any patent rights identified during the development o f 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 in formation given for the convenience o f users and does not constitute an endorsement For an explanation on the voluntary nature o f standards, the meaning o f ISO specific terms and expressions related to formity assessment, as well as in formation about ISO’s adherence to the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see the following URL: www.iso org/iso/foreword html This document was prepared by Technical Committee ISO/TC 102, , Subcommittee SC 2, This third edition cancels and replaces the second edition (ISO 4689-3:2015), of which it constitutes a minor revision, with the following changes: — “0,001 %” has been inserted before “sulfur” in 5.1; — in 6.7: — under “Combustion crucible”, “Length” has been changed to “Height”; — under “Combustion crucible”, outer diameter has been changed from “10 mm” to “26 mm”; — under “Combustion crucible”, inner diameter has been changed from “26 mm” to “10 mm”; — “0,2 g” has been added after “sulfur” in 8.2; — Formula (7) and the relevant descriptions in 9.2.4 have been modified to harmonize this clause across all standards for which ISO/TC 102/SC is responsible A list of all parts in the ISO 4689 series can be found on the ISO website Iron ore an d direct reduced iron Ch emical an alysis iv © ISO 2017 – All rights reserved ISO 4689-3 : 01 7(E) Introduction I S O -2 wa s origi na l ly publ i she d a s I S O 69 : 19 Under a p ol ic y o f rationa l i z ation o f the numb eri ng s ys tem u s e d i n I S O/ TC 10 , it h as b e en de c ide d to re - de s ignate I S O 69 : 19 a s I S O -2 I t was further decided to introduce a combustion/infrared method, numbered ISO 4689-3, i.e this document When next revised, ISO 4689:1986 will be re-designated as ISO 4689-1 © ISO 2017 – All rights reserved v INTERNATIONAL STANDARD ISO 4689-3 : 01 7(E) Iron ores — Determination of sulfur content — Part 3: Combustion/infrared method WARNING — This document may involve hazardous materials, operations, and equipment This document does not purport to address all of the safety problems associated with its use It is the responsibility of the user of this document to establish appropriate health and safety practices and determine the applicability of regulatory limitations prior to use Scope T h i s c ument s p e ci fie s a combu s tion/i n fra re d me tho d , u s i ng a h igh- fre quenc y i nduc tion furnace, for the determination of the sulfur content of iron ores This method is applicable to sulfur contents between 0,002 % (mass fraction) and 0,25 % (mass fraction) in natural iron ores, iron ore concentrates and agglomerates, including sinter products The method is not applicable to iron ores containing more than 1,0 % (mass fraction) of combined water f containing less than 3,0 % (mass fraction) of combined water T he app aratu s , o T he wh ich the me ta l fi lter i s e qu ipp e d with a he ati ng device, c an b e appl ie d to i ron ore s Normative references fol lowi ng c u ments are re ferre d to i n the tex t i n s uch a way th at s ome or a l l o f thei r content s titute s re qu i rements o f th i s c u ment For date d re ference s , on ly the e d ition cite d appl ie s For u ndate d re ference s , the late s t e d ition o f the re ference d c ument (i nclud i ng a ny amend ments) appl ie s ISO 648, ISO 1042, Laboratory glassware — One-mark volumetric flasks ISO 2596, Laboratory glassware — Sin gle-volum e pipettes Iron ores — Determin ation of hygroscopic m oisture in an alytical samples — Gravim etric, Karl Fisch er an d m ass-loss m eth ods ISO 3082, ISO 7764, ISO Guide 35, Reference materials — General and statistical principles for certification Iron ores — Sam plin g an d sample preparation procedures Iron ores — Preparation of predried test samples for ch emical an alysis Terms and definitions No term s and defi nition s a re l i s te d i n th i s c u ment ISO and IEC maintain terminological databases for use in standardization at the following addresses: — IEC Electropedia: available at http://www.electropedia org/ — ISO Online browsing platform: available at http://www.iso org/obp © ISO 2017 – All rights reserved ISO 4689-3 : 01 7(E) Principle T he s a mple i s m i xe d with a flu x conta i n i ng i ron, ti n and tungs ten and he ate d i n a h igh- fre quenc y i nduc tion T he fu rnace, evolve d u s i ng ox ygen as a s upp or ti ng s u l fu r d ioxide absorption scale is read is c arrie d by fuel ox ygen and c arrier gas i nto the cel l o f an i n frare d de te c tor, where the Reagents D u ri ng ana lys i s , u s e on ly re agents o f re co gn i ze d ana lytic a l grade, and on ly d i s ti l le d water or water o f e qu iva lent pu rity particle size 0,2 mm to 1,2 mm containing less than 0,001 % sulfur Metallic iron, Magnesium perchlorate, Iron(III) oxide, Metallic tin, 5 Metallic tungsten Sodium hydroxide coated silica, Sodium hydroxide Standard sulfur solution Mg(ClO 4) , anhydro us , free flowing, p article s ize , mm to mm containing less than 0,003 % sulfur particle size 0,2 mm to 1,2 mm, containing less than 0,001 % sulfur , particle size 0,2 mm to 1,2 mm containing less than 0,001 % sulfur particle size 0,5 mm to mm , particle size 0,5 mm to mm , prepared as follows D r y g o f potas s ium s ul fate [purity > 9,9 % (mas s frac tion)] to cons tant mas s at 105 °C to 110 °C and cool in a des iccator Weigh the dried mas ses o f potas s ium s ul fate s p eci fied in Table and dissolve each portion in water Co ol, trans fer each portion to separate volumetric flasks and dilute to volume with water Table — Sulfur standard solution (calibration series) Solution no Mass of potassium sulfate g 0,543 1,087 1,902 2,717 Concentration of sulfur mg/ml 1,00 2,00 3,50 5,00 Apparatus O rd i na r y lab orator y app aratu s , i nclud i ng one -mark pip e tte s and one -mark volu me tric fla s ks complyi ng with the s p e ci fic ation s o f I S O and I S O 10 42 , re s p e c tively, a s wel l a s the 6.1 Oxygen supply 6.2 Absorption tower, 6.3 Drying tower, containing soda-asbestos (5.6 fol lowi ng ) o r s o dium hydroxide ( See Figure 5.7) containing magnesium perchlorate (5.2) © ISO 2017 – All rights reserved ISO 4689-3 : 01 7(E) 6.4 High-frequency induction furnace , having a heating induction coil (height 30 mm to 55 mm, to rolls), capable o f heating to a temperature o f 200 °C An example o f a combustion furnace, with combustion gas-refining section, is given in Figure quartz 6.5 Combustion tube, 6.6 Refractory combustion crucible Key a b metal filter heating device quartz combustion tube dust trap high- frequency induction coil crucible holder Oxygen Combustion gas F i g u r e — E x a m © ISO 2017 – All rights reserved p l e o f c o m b u s t i o n f u r n a c e w i t h c o m b u s t i o n g a s - r e f i n i n g s e c t i o n ISO 4689-3 : 01 7(E) 6.7 Tin capsule T he fol lowi ng d i men s ion s may b e u s e d as gu idel i ne s Combustion tube Length 140 m to 220 m Outer diameter 30 mm to 44 mm Inner diameter 26 mm to 37 mm M e t a l f i l t e r Combustion crucible Height 26 mm Outer diameter 26 mm Inner diameter 10 mm , containing glass wool Dust trap 6.1 Detector for infrared absorption 6.1 Micro-pipette , a b mm 18 mm 0,3 g 0,4 ml 6.9 Key Tin capsule Diameter Height Mass Volume , an example of which is shown in Figure cap acity 0 μl, accurate to μl chopper measuring cell infrared detector motor infrared source filter cell reference cell Combustion gas O xygen Figure — E xample of an infrared detection system © ISO 2017 – All rights reserved ISO 4689-3 : 01 7(E) Sampling and samples 7.1 Laboratory sample For analysis, use a laboratory sample o f −100 μm particle size which has been taken and prepared in accordance with ISO 3082 In the case o f ores having significant contents o f combined water or oxidizable compounds, use a particle size o f −160 μm NOTE ISO 7764 7.2 A guideline on significant contents o f combined water and oxidizable compounds is incorporated in Preparation of predried test samples Thoroughly mix the laboratory sample and, taking multiple increments, extract a test sample in such a manner that it is representative o f the entire contents o f the container Dry the test sample at 105 °C ± °C as specified in ISO 7764 This is the predried test sample For ores having significant content o f combined water or oxidizable compounds, an air-equilibrated test sample shall be prepared in accordance with ISO 2596 8.1 Procedure Number of determinations Carry out the analysis at least in duplicate in accordance with Annex A , independently, on one predried test sample NOTE The expression “independently” means that the second and any subsequent result are not a ffected by the previous result(s) For this particular analytical method, this condition implies that the repetition o f the procedure is carried out either by the same operator at a di fferent time or by a di fferent operator, including in either case, appropriate recalibration 8.2 Test portion Taking several increments, weigh to the nearest 0,000 g, approximately 0,5 g o f the predried test sample obtained in accordance with 7.2 For samples containing in excess of 0,1 % (mass fraction), sulfur 0,2 g should be taken The test portion should be taken and weighed quickly to avoid re-absorption o f moisture 8.3 Blank test and check test In each run, one blank test and one analysis o f a certified re ference material o f the same type o f ore shall be carried out in parallel with the analysis o f the ore sample(s) under the same conditions A predried test sample o f the certified re ference material shall be prepared as specified in 7.2 The certified re ference material should be o f the same type as the sample to be analysed, and the properties o f the two materials should be su fficiently similar to ensure that in either case, no significant changes in the analytical procedure will become necessary Where the analysis is carried out on several samples at the same time, the blank value may be represented by one test, provided that the procedure is the same and the reagents are from the same reagent bottles Where the analysis is carried out on several samples o f the same type o f ore at the same time, the analytical value o f one certified re ference material may be used © ISO 2017 – All rights reserved ISO 4689-3 : 01 7(E) 8.4 Determination Connect the furnace (6.4) with components (6.1, 6.2, 6.3, 6.5, 6.8, 6.9, and 6.10) and switch on the power Set the condition for heating in accordance with the manufacturer’s instructions after stabilization of the apparatus Analyse a standardization sample as follows a) Adjust the reading o f the detector to the sul fur content o f the standardization sample Place the test portion in a re fractory combustion crucible (6.6) and cover the test portion with 0,50 g of iron (5.1), 0,3 g to 0,5 g of tin (5.4), and 1,0 g of tungsten (5.5) in that order For 0,2 g of sample, cover the test portion with 0,8 g of iron, 0,3 g to 0,5 g of tin, and 1,0 g of tungsten in that order b) Insert the crucible into a quartz combustion tube (6.5) of the furnace at the centre position of the heating induction coil Substitute oxygen for air in the combustion tube, adjust the inner pressure to the specified pressure and load the power to the heating induction coil Continue combustion o f the test portion until the reading o f the detector does not vary Read out and record the indicated value Switch off the power and take out the crucible c) After combustion, the used crucible shall be checked to determine whether the combustion is complete or not d) If incomplete, the test shall be carried out again A standardization sample means a sample used for adjusting the sensitivity o f a detector It should not easily degenerate and should be homogeneous NOTE 8.5 An apparatus equipped with a timer stops automatically Preparation of calibration graph Decant water and sulfur standard solution (5.8), in accordance with Table , into five tin capsules (6.7) Heat each capsule gently at 90 °C, to dryness, and cool in a desiccator Place the dried capsule in a re fractory combustion crucible (6.6) and press the capsule against the bottom of the crucible Cover the capsule with 0,5 g of iron oxide (5.3), 0,5 g of iron (5.1), and 1,0 g of tungsten (5.5) in that order Treat each crucible as described in 8.4 Plot the relationship between the quantity of sul fur, in micrograms, and the net reading Several CRMs may be used instead o f sul fur standard solutions In this case, the sul fur contents o f the CRMs should cover the applicable range of this method CRMs should be treated as indicated in 8.3 and 8.4 Table — Aliquot of sulfur standard solution No of sulfur s tandard solution (Water) Volume of aliquot µl 100 100 100 100 100 M ass of sulfur in aliquot mg 0,100 0,200 0,350 0,500 © ISO 2017 – All rights reserved ISO 4689-3 : 01 7(E) Expression of results 9.1 Calculation of sulfur content The sulfur content, ws f than 0,01 % and to six decimal places for contents lower than 0,01 %, using Formula , i s ca lc u late d a s a p ercentage b y ma s s , to five de ci ma l place s w s (%) = where m1 m2 m 9.2 or contents h igher m1 − m m × 10 (1) is the mass, in micrograms, of sulfur in the test portion; is the mass, in micrograms, of sulfur in the blank test; is the mass, in grams, of the test portion General treatment of results 9.2 Repeatability and permissible tolerance T he pre c i s ion o f th i s a na lytic a l me tho d i s e xpre s s e d b y the NOTE Rd fol lowi ng formu l ae: Additional information is given in Annexes B and C = 030 X + 000 66 , , (3) P = 137 977 X 781 21 , , σd = σL = X+0 , 010 , 048 827 X , (2) (4) 000 23 (5) , 791 96 where Rd P σd σL X is the independent duplicate limit; is the permissible tolerance between laboratories; is the independent duplicate standard deviation; is the between-laboratories standard deviation; Formulae (2) and (4) Formulae (3) and (5) (9.2.5) of the two laboratories 9.2 - i s the s u l fu r content, e xpre s s e d as a p ercentage b y ma s s , o f the pre d rie d te s t s a mple c a lc u lat ed as follows: — with i n-l ab orator y [ — b e twe en-lab oratorie s [ ] : the a rith me tic me a n o f the dupl ic ate va lue s; ] : the arith me tic me an o f the fi na l re s u lts Determination of analytical result Having computed the independent duplicate results according to Formula (1), compare them with the independent duplicate limit, Rd, using the procedure given in Annex A © ISO 2017 – All rights reserved ISO 4689-3 : 01 7(E) 9.2 Between-laboratories precision B e twe en-l ab oratorie s pre c i s ion i s u s e d to de term i ne the agre ement b e twe en the fi na l re s u lts rep or te d by two lab oratorie s T he as s u mp tion i s that b o th l ab oratorie s in 9.2.2 C ompute the µ 1,2 = fol lowi ng fol lowe d the s ame pro ce dure de s crib e d qua ntity: µ1 + µ2 (6) where μ1 i s the fi na l re s u lt rep or te d b y l ab orator y ; μ2 i s the fi na l re s u lt rep or te d b y l ab orator y ; μ1,2 i s the me an o f the fi na l re s u lts If µ − µ ≤ P , the results are in agreement 9.2 Check for trueness T he truene s s o f the ana lytic a l me tho d sh a l l b e che cke d by applyi ng it to a cer ti fie d re ference materi a l (CRM) or a reference material (RM) The procedure is the same as that described above After f f value, Ac There are two possibilities: ff f a) µ c − Ac ≤ C fi rmation o the pre c i s ion, the fi na l lab orator y re s u lt i s comp a re d with the re erence or cer ti fie d , i n wh ich c a s e, the d i erence b e twe en the rep or te d re s u lt and the re erence/cer ti fie d va lue i s s tati s tic a l ly i n s ign i fic ant b) µ c − A c > C , i n wh ich c a s e, the d i fference b e twe en the rep or te d re s u lt and the re ference/cer ti fie d va lue i s s tati s tic a l ly s ign i fic ant where μc i s the fi na l re s u lt Ac i s the re ference/cer ti fie d va lue C i s a va lue dep endent on the typ e o f C RM/RM u s e d for the cer ti fie d re ference materi a l; C er ti fie d re ference materi a l s u s e d ISO Guide 35 C should be calculated as follows: C=2 s Lc + s Wc n Wc Nc + σ L2 σ d2 + n for for th i s the C RM/RM ; pu rp o s e shou ld b e prep are d and cer ti fie d i n accorda nce with (7) © ISO 2017 – All rights reserved ISO 4689-3 : 01 7(E) where sLc is the between-laboratories standard deviation o f the certi fying laboratories; sWc is the within-laboratory standard deviation o f the certi fying laboratories; n Wc is the average number o f replicate determinations in the certi fying laboratories; Nc is the number o f certi fying laboratories; is the number of replicate determinations carried out on the CRM/RM; σL and σd are as defined in 9.2.1 n The following procedure should be used when the in formation on the re ference material certificate is incomplete: — i f there are su fficient data to enable the between-laboratories standard deviation to be estimated, / n Wc and regard sLc as the standard deviation o f the laboratory means; delete the expression s Wc — i f the certification has been made by only one laboratory or i f the interlaboratory results are missing, use the following condition: C=2 σ L2 + σ d2 (8) n A CRM certified by only one laboratory should be avoided unless it is known to have an unbiased certified value C a l c u l a t i o n o f f i n a l r e s u l t The final result is the arithmetic mean o f the acceptable analytical values for the test sample, or as otherwise determined by the operations specified in Annex A , calculated to five decimal places for contents of sulfur higher than 0,01 % (mass fraction) and to six decimal places for contents lower than 0,01 % (mass fraction) For contents higher than 0,01 % (mass fraction), the value is rounded off to the third decimal place as specified in a), b), and c) In a similar manner, with the ordinal numbers increased by one, the value for sul fur contents lower than 0,01 % (mass fraction) is rounded o ff to the fourth decimal place a) Where the figure in the fourth decimal place is less than five, it is discarded and the figure in the third decimal place is kept unchanged b) Where the figure in the fourth decimal place is five and there is a figure other than in the fi fth decimal place, or i f the figure in the fourth decimal place is greater than five, the figure in the third decimal place is increased by one c) Where the figure in the fourth decimal place is five and the figure is in the fi fth decimal place, the five is discarded and the figure in the third decimal place is kept unchanged i f it is 0, 2, 4, 6, or 8, and is increased by one i f it is 1, 3, 5, 7, or Test report The test report shall include the following information: a) name and address o f the testing laboratory; b) date of issue of the test report; c) reference to this document, i.e ISO 4689-3; © ISO 2017 – All rights reserved ISO 4689-3 : 01 7(E) for d) de tai l s ne ce s s ar y e) re s u lt o f the ana lys i s; the identi fic ation o f the s ample; f) reference number of the result; g) any charac teri s tics no tice d duri ng the de term i nation and any op eration s c u ment, wh ich may h ave h ad an i n fluence on the re s u lt, either for no t s p e ci fie d i n th i s the te s t s ample or for the cer ti fie d re ference materia l(s) 10 © ISO 2017 – All rights reserved ISO 4689-3 : 01 7(E) Annex A (normative) Flowsheet of the procedure for the acceptance of analytical values for test samples Figure A.1 NOTE shows the pro ce du re for the accep ta nce o f ana lytic a l va lue s for te s t s ample s Rd i s a s de fi ne d i n 9.2.1 Figure A.1 — Flowsheet of the procedure for the acceptance of analytical values for test samples © ISO 2017 – All rights reserved 11 ISO 4689-3 : 01 7(E) Annex B (informative) Derivation of repeatability and permissible tolerance equations The regression formulae in 9.2.1 f f out in 1999/2000 on seven iron ore samples, involving six laboratories in four countries Graphical treatment of the precision data is given in Annex C The test samples used are listed in Table B.1 were derive d rom the re s u lts o i nternationa l ana lytic a l tria l s c a rrie d NO TE Rep o r ts o f the i nter n atio n a l tr i a l a nd a s tati s tic a l a n a l ys i s o f the re s u lts ( D o c u ments I S O/ TC 10 /S C NO TE T he s tati s tic a l a n a l ys i s wa s p er fo r me d i n acco rda nce with the pr i nc ip le s emb o d ie d i n I S O -2 N1419 and N1422, September 2000) are available from the Secretariat of ISO/TC 102/SC Table B — Sulfur contents of test samples S ample WG 4–5 WG 4–3 WG 4–4 WG 4–1 WG 4–2 WG 4–6 WG 4–7 12 Sulfur content % (mass fraction) 0,004 50 0,005 79 0,011 0,208 0,032 0,110 0,527 © ISO 2017 – All rights reserved ISO 4689-3 : 01 7(E) Annex C (informative) Precision data obtained by international analytical trial Figure C.1 is a graphical presentation of the formulae in 9.2.1 Key X sulfur content, % mass fraction Y precision, % F i g u r e C © ISO 2017 – All rights reserved — L e a s t - s q u a r e s f i t o f p r e c i s i o n a g a i n s t X f o r s u l f u r 13 ISO 4689-3 : 01 7(E) Bibliography [1] [2 ] ISO 85, Laboratory glassware — Burettes ISO 5725-2, Accuracy (trueness and precision) of measurement methods and results — Part 2: Basic method for the determination of repeatability and reproducibility of a standard measurement method 14 © ISO 2017 – All rights reserved