1、BS ISO 4689-2:2017Iron ores Determination of sulfur contentPart 2: Combustion/titration methodBSI Standards PublicationWB11885_BSI_StandardCovs_2013_AW.indd 1 15/05/2013 15:06BS ISO 4689-2:2017 BRITISH STANDARDNational forewordThis British Standard is the UK implementation of ISO 4689-2:2017. It sup
2、ersedes BS ISO 4689-2:2015 which is withdrawn.The UK participation in its preparation was entrusted to Technical Committee ISE/58, Iron ores.A list of organizations represented on this committee can be obtained on request to its secretary.This publication does not purport to include all the necessar
3、y provisions of a contract. Users are responsible for its correct application. The British Standards Institution 2017.Published by BSI Standards Limited 2017ISBN 978 0 580 95541 9 ICS 73.060.10 Compliance with a British Standard cannot confer immunity from legal obligations.This British Standard was
4、 published under the authority of the Standards Policy and Strategy Committee on 31 March 2017.Amendments/corrigenda issued since publicationDate T e x t a f f e c t e dBS ISO 4689-2:2017 ISO 2017Iron ores Determination of sulfur content Part 2: Combustion/titration methodMinerais de fer Dosage du s
5、oufre Partie 2: Mthode par combustion et titrationINTERNATIONAL STANDARDISO4689-2Third edition2017-03Reference numberISO 4689-2:2017(E)BS ISO 4689-2:2017ISO 4689-2:2017(E)ii ISO 2017 All rights reservedCOPYRIGHT PROTECTED DOCUMENT ISO 2017, Published in SwitzerlandAll rights reserved. Unless otherwi
6、se specified, no part of 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 bel
7、ow or ISOs member body in the country of the requester.ISO copyright officeCh. de Blandonnet 8 CP 401CH-1214 Vernier, Geneva, SwitzerlandTel. +41 22 749 01 11Fax +41 22 749 09 47copyrightiso.orgwww.iso.orgBS ISO 4689-2:2017ISO 4689-2:2017(E)Foreword ivIntroduction v1 Scope . 12 Normative references
8、13 Terms and definitions . 14 Principle 15 Reagents 26 Apparatus . 27 Sampling and samples 57.1 Laboratory sample . 57.2 Preparation of predried test samples 58 Procedure. 58.1 Number of determinations . 58.2 Test portion 58.3 Blank test and check test 58.4 Determination . 69 Expression of results 7
9、9.1 Calculation of sulfur content . 79.2 General treatment of results . 79.2.1 Repeatability and permissible tolerance 79.2.2 Determination of analytical result 89.2.3 Between-laboratories precision . 89.2.4 Check for trueness 89.2.5 Calculation of final result 910 Test report . 9Annex A (normative)
10、 Flowsheet of the procedure for the acceptance of analytical values for test samples 11Annex B (informative) Derivation of repeatability and permissible tolerance equations 12Annex C (informative) Precision data obtained by international analytical trial 13Bibliography .14 ISO 2017 All rights reserv
11、ed iiiContents PageBS ISO 4689-2:2017ISO 4689-2:2017(E)ForewordISO (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.
12、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 Internat
13、ional 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 differ
14、ent 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 sha
15、ll 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 documen
16、t is information given for the convenience of users and does not constitute an endorsement. For an explanation on the voluntary nature of standards, the meaning of ISO specific terms and expressions related to conformity assessment, as well as information about ISOs adherence to the World Trade Orga
17、nization (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, Iron ore and direct reduced iron, Subcommittee SC 2, Chemical analysis.This third edition cancels and replaces th
18、e second edition (ISO 4689-2:2015), which constitutes a minor revision with the following changes: 6.7: first line, after “approximately”, insert “10 g”; 9.2.4: modify Formula (7) and the relevant descriptions, to harmonize this subclause across all standards for which ISO/TC 102/SC 2 is responsible
19、.A list of all parts in the ISO 4689 series can be found on the ISO website.iv ISO 2017 All rights reservedBS ISO 4689-2:2017ISO 4689-2:2017(E)IntroductionThis document was originally published as ISO 4690:1986. Under a policy of rationalization of the numbering system used in ISO/TC 102, it has bee
20、n decided to re-designate this document as ISO 4689-2. It was further decided to introduce a combustion/infrared method, numbered ISO 4689-3.When next revised, ISO 4689:1986 will be re-designated as ISO 4689-1. ISO 2017 All rights reserved vBS ISO 4689-2:2017BS ISO 4689-2:2017Iron ores Determination
21、 of sulfur content Part 2: Combustion/titration methodWARNING 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 app
22、ropriate health and safety practices and determine the applicability of regulatory limitations prior to use.1 ScopeThis document specifies a combustion/titration method for the determination of the sulfur content of iron ores.This method is applicable to sulfur contents between 0,002 % (mass fractio
23、n) and 0,25 % (mass fraction) in natural iron ores, iron ore concentrates, and agglomerates, including sinter products. The results are not affected by the presence of fluoride.2 Normative referencesThe following documents are referred to in the text in such a way that some or all of their content c
24、onstitutes 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 385, Laboratory glassware BurettesISO 648, Laboratory glassware Single-volume pipettesISO 1042,
25、 Laboratory glassware One-mark volumetric flasksISO 2596, Iron ores Determination of hygroscopic moisture in analytical samples Gravimetric, Karl Fischer and mass-loss methodsISO 3082, Iron ores Sampling and sample preparation proceduresISO 7764, Iron ores Preparation of predried test samples for ch
26、emical analysisISO Guide 35, Reference materials General and statistical principles for certification3 Terms and definitionsNo terms and definitions are listed in this document.ISO and IEC maintain terminological databases for use in standardization at the following addresses: IEC Electropedia: avai
27、lable at h t t p :/ www .electropedia .org/ ISO Online browsing platform: available at h t t p :/ www .iso .org/ obp4 PrincipleThe sample is mixed with tungsten(VI) oxide and heated at 1 200 C in a resistance furnace, using nitrogen as a carrier gas.INTERNATIONAL STANDARD ISO 4689-2:2017(E) ISO 2017
28、 All rights reserved 1BS ISO 4689-2:2017ISO 4689-2:2017(E)The evolved sulfur dioxide is absorbed in dilute hydrochloric acid solution containing starch and potassium iodide, and the solution is titrated continuously during evolution with a standard volumetric solution of potassium iodate.5 ReagentsD
29、uring analysis, use only reagents of recognized analytical grade, and only distilled water or water of equivalent purity.5.1 Magnesium perchlorate, Mg(ClO4)2, anhydrous, free flowing, particle size 0,5 mm to 2 mm.5.2 Tungsten(VI) oxide, (WO3).5.3 Tin(II) chloride, SnCl22H2O, particle size 0,5 mm to
30、2 mm.5.4 Sodium hydroxide coated silica, particle size 0,5 mm to 2 mm.5.5 Hydrochloric acid, , 1,16 g/ml to 1,19 g/ml, diluted 1 + 66.5.6 Potassium iodide, KI, 3 % (mass fraction) solution.5.7 Starch, 2 % (mass fraction) solution.Make a suspension of 2,0 g of starch in 10 ml of water, add to 50 ml o
31、f boiling water and stir. Cool, dilute to 100 ml and mix.Prepare this solution immediately prior to use.5.8 Potassium iodate, KIO3, standard volumetric solution, 0,001 042 mol/l.The potassium iodate should be previously dried for 2 h at 130 C.Weigh, to the nearest 0,000 2 g, 0,223 g of dried potassi
32、um iodate and dissolve in water. Cool, transfer to a 1 l volumetric flask, dilute to volume and mix.1 ml of this standard volumetric solution is equivalent to 0,10 mg of sulfur.6 ApparatusOrdinary laboratory apparatus, including one-mark pipettes and one-mark volumetric flasks complying with the spe
33、cifications of ISO 648 and ISO 1042 respectively, as well as the following. See Figure 1.6.1 Nitrogen supply.6.2 Drying tower, containing sodium hydroxide coated silica (5.4) and magnesium perchlorate (5.1).6.3 Flowmeter, graduated from 0 to 1 l/min.6.4 Resistance furnace, capable of maintaining a t
34、emperature of 1 200 C 25 C.6.5 Refractory combustion tube, capable of withstanding a temperature of 1 200 C 25 C.2 ISO 2017 All rights reservedBS ISO 4689-2:2017ISO 4689-2:2017(E)6.6 Refractory combustion boat, with loose-fitting lid, or a suitable refractory combustion boat capable of accommodating
35、 a porous cartridge, as shown in Figure 2 a) or b) respectively.The following dimensions can be used as guidelines.Combustion boat Cartridge Length 80 mm Length 50 mmWidth 13 mm Internal diameter 15 mmDepth 9 mm 6.7 Tin(II) chloride absorption tube, of narrow glass tubing containing approximately 10
36、 g of solid tin(II) chloride (5.3), suitably plugged with inert wool to prevent the reagent being blown into the absorption vessel.A U-tube is suitable. Where necessary, this is inserted in the train at the exit of the combustion tube at point X in Figure 1.If the sample is known or thought to conta
37、in chloride, e.g. in the form of sodium chloride, chlorapatite, or scapolite, the chlorine formed during combustion of the sample should be removed by passing the gas stream through solid tin(II) chloride in a suitable tube or vessel (6.7) prior to absorption and titration. If numerous samples havin
38、g chloride contents 1 (mass fraction) are to be analysed, it is advisable to determine the absorption capacity of the tin(II) chloride in order to be able to judge the most suitable interval for reagent replacement. In such cases, a larger absorption vessel may be preferred.The tin(II) chloride abso
39、rption tube should also be fitted if the chloride content of the test sample is unknown.6.8 Cylinder, 100 ml, tall form, to hold the absorbing solution.6.9 Bubbler, multi-hole, to reach to the bottom of the cylinder (6.8).6.10 Burette, conforming to ISO 385, graduated in divisions of 0,05 ml.For det
40、ermination of low sulfur contents the equivalent of 0,001 % (mass fraction) in the test sample, this may be due to the presence of sulfur compounds either in the tungsten(VI) oxide or in the refractory boats/porous cartridges used. Tungsten(VI) oxide (5.2) can be pre-treated by heating for 2 h at a
41、temperature of 800 C, and the blank in the combustion boats/cartridges can be reduced by allowing them to stand overnight in a suitable furnace at a temperature of 1 200 C and then storing in a desiccator prior to use. Such pre-treatment of tungsten(VI) oxide and the combustion boats is also require
42、d if the sulfur content of the test sample is less than 0,01 % (mass fraction).6 ISO 2017 All rights reservedBS ISO 4689-2:2017ISO 4689-2:2017(E)9 Expression of results9.1 Calculation of sulfur contentThe sulfur content, ws, is calculated as a percentage by mass, to five decimal places for contents
43、higher than 0,01 % and to six decimal places for contents lower than 0,01 %, using Formula (1).wVVms12(%) = 100(1)whereV1is the volume, in millilitres, of standard potassium iodate solution (5.8) used in the titration of the test portion;V2is the volume, in millilitres, of standard potassium iodate
44、solution (5.8) used in the blank titration;m is the mass, in grams, of the test portion.9.2 General treatment of results9.2.1 Repeatability and permissible toleranceThe precision of this analytical method is expressed by the following formulae:NOTE Additional information is given in Annexes B and C.
45、RXd= 0 011 980 518 3,(2)PX=+0 114 59 0 000 85, (3)d= 0 004 2330 518 3,X (4)L=+0 038 70 0 000 23,X (5)whereRdindependent duplicate limit;P is the permissible tolerance between laboratories;dis the independent duplicate standard deviation;Lis the between-laboratories standard deviation;X is the sulfur
46、 content, expressed as a percentage by mass, of the predried test sample calculat-ed as follows: within-laboratory Formulae (2) and (4): the arithmetic mean of the duplicate values; between-laboratories Formulae (3) and (5): the arithmetic mean of the final results (9.2.5) of the two laboratories. I
47、SO 2017 All rights reserved 7BS ISO 4689-2:2017ISO 4689-2:2017(E)9.2.2 Determination of analytical resultHaving computed the independent duplicate results according to Formula (1), compare them with the independent duplicate limit, Rd, using the procedure given in Annex A.9.2.3 Between-laboratories
48、precisionBetween-laboratories precision is used to determine the agreement between the final results reported by two laboratories. The assumption is that both laboratories followed the same procedure described in 9.2.2.Compute the following quantity:1,212=+2(6)where1is final result reported by labor
49、atory 1;2is the final result reported by laboratory 2;1,2is the mean of final results.If 12P , the results are in agreement.9.2.4 Check for truenessThe trueness of the analytical method shall be checked by applying it to a certified reference material (CRM) or a reference material (RM). The procedure is the same as that described above. After confirmation of the precision, the final laboratory result is compared with the reference or certified value, Ac. There are two possibilities
