1、BSI Standards PublicationBS ISO 11257:2015Iron ores for shaft direct-reduction feedstocks Determination of the low-temperature reduction-disintegration index anddegree of metallizationBS ISO 11257:2015 BRITISH STANDARDNational forewordThis British Standard is the UK implementation of ISO 11257:2015.
2、 Itsupersedes BS ISO 11257:2007 which is withdrawn.The UK participation in its preparation was entrusted to TechnicalCommittee ISE/58, Iron ores.A list of organizations represented on this committee can beobtained on request to its secretary.This publication does not purport to include all the neces
3、saryprovisions of a contract. Users are responsible for its correctapplication. The British Standards Institution 2015. Published by BSI StandardsLimited 2015ISBN 978 0 580 79287 8ICS 73.060.10Compliance with a British Standard cannot confer immunity fromlegal obligations.This British Standard was p
4、ublished under the authority of theStandards Policy and Strategy Committee on 31 August 2015.Amendments issued since publicationDate Text affectedBS ISO 11257:2015 ISO 2015Iron ores for shaft direct-reduction feedstocks Determination of the low-temperature reduction-disintegration index and degree o
5、f metallizationMinerais de fer pour charges utilises dans les procds par rduction directe Dtermination de lindice de dsintgration par rduction basse temprature et du degr de mtallisationINTERNATIONAL STANDARDISO11257Third edition2015-08-15Reference numberISO 11257:2015(E)BS ISO 11257:2015ISO 11257:2
6、015(E)ii ISO 2015 All rights reservedCOPYRIGHT PROTECTED DOCUMENT ISO 2015, Published in SwitzerlandAll rights reserved. Unless otherwise 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 p
7、osting on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below 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
8、 22 749 09 47copyrightiso.orgwww.iso.orgBS ISO 11257:2015ISO 11257:2015(E)Foreword ivIntroduction v1 Scope . 12 Normative references 13 Terms and definitions . 14 Principle 15 Sampling, sample preparation, and preparation of test portions 25.1 Sampling and sample preparation . 25.2 Preparation of te
9、st portion . 26 Apparatus . 26.1 General . 27 Test conditions . 37.1 General . 37.2 Reducing gas . 37.2.1 Composition . 37.2.2 Purity . 37.2.3 Flow rate . 37.3 Heating and cooling gas 37.4 Temperature of the test portion . 38 Procedure. 48.1 Number of determinations for the test 48.2 Reduction . 48.
10、3 Sieving 48.4 Chemical analysis 49 Expression of results 59.1 Calculation of the reduction-disintegration index (RDIDR) 59.2 Calculation of the degree of metallization (M) 59.3 Repeatability and acceptance of test results . 510 Test report . 611 Verification . 6Annex A (normative) Flowsheet of the
11、procedure for the acceptance of test results 8Bibliography 9 ISO 2015 All rights reserved iiiContents PageBS ISO 11257:2015ISO 11257:2015(E)ForewordISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of prepari
12、ng 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 lia
13、ison with ISO, also take part in the work. ISO collaborates closely with the International 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 Dir
14、ectives, Part 1. In particular the different approval criteria needed for the different 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 s
15、ome 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. 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 decla
16、rations received (see www.iso.org/patents).Any trade name used in this document is information given for the convenience of users and does not constitute an endorsement.For an explanation on the meaning of ISO specific terms and expressions related to conformity assessment, as well as information ab
17、out ISOs adherence to the WTO principles in the Technical Barriers to Trade (TBT), see the following URL: Foreword Supplementary informationThe committee responsible for this document is ISO/TC 102, Iron ore and direct reduced iron, Subcommittee SC 3, Physical testing.This third edition cancels and
18、replaces the second edition (ISO 11257:2007), of which it constitutes a minor revision to contemplate the care needed during hand sieving, to introduce the mechanical sieving and to exclude the reference to ISO 4701.iv ISO 2015 All rights reservedBS ISO 11257:2015ISO 11257:2015(E)IntroductionThis In
19、ternational Standard concerns one of a number of physical test methods that have been developed to measure various physical parameters and to evaluate the behaviour of iron ores, including reducibility, disintegration, crushing strength, apparent density, etc. This method was developed to provide a
20、uniform procedure, validated by collaborative testing, to facilitate comparisons of tests made in different laboratories.The results of this test have to be considered in conjunction with other tests used to evaluate the quality of iron ores as feedstocks for direct reduction processes.This Internat
21、ional Standard can be used to provide test results as part of a production quality control system, as a basis of a contract, or as part of a research project. ISO 2015 All rights reserved vBS ISO 11257:2015BS ISO 11257:2015Iron ores for shaft direct-reduction feedstocks Determination of the low-temp
22、erature reduction-disintegration index and degree of metallizationCAUTION This International Standard can involve hazardous operations and equipment. International Standard does not purport to address all of the safety issues associated with its use. It is the responsibility of the user of this Inte
23、rnational Standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to its use.1 ScopeThis International Standard specifies a method to provide a relative measure for evaluating the degree of size degradation and degree of metalliza
24、tion of iron ores, when reduced under conditions resembling those prevailing in shaft direct-reduction processes.This International Standard is applicable to lump ores and hot-bonded pellets.2 Normative referencesThe following documents, in whole or in part, are normatively referenced in this docume
25、nt and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.ISO 2597-1, Iron ores Determination of total iron content Part 1: Titrimetric method after tin(
26、II) chloride reductionISO 2597-2, Iron ores Determination of total iron content Part 2: Titrimetric methods after titanium(III) chloride reductionISO 3082, Iron ores Sampling and sample preparation proceduresISO 3310-1, Test sieves Technical requirements and testing Part 1: Test sieves of metal wire
27、 clothISO 3310-2, Test sieves Technical requirements and testing Part 2: Test sieves of perforated metal plateISO 5416, Direct reduced iron Determination of metallic iron Bromine-methanol titrimetric methodISO 11323, Iron ore and direct reduced iron Vocabulary3 Terms and definitionsFor the purposes
28、of this document, the terms and definitions given in ISO 11323 apply.4 PrincipleThe test portion is isothermally reduced in a rotating tube bed, at 760 C, using a reducing gas consisting of H2, CO, CO2, and CH4, for 300 min. The reduced product is sieved with a sieve having square openings of 3,15 m
29、m. Then, it is analysed for total iron and metallic iron. The reduction-disintegration index is calculated as the mass percentage of material less than 3,15 mm. The degree of metallization is calculated from the chemical analysis results.INTERNATIONAL STANDARD ISO 11257:2015(E) ISO 2015 All rights r
30、eserved 1BS ISO 11257:2015ISO 11257:2015(E)5 Sampling, sample preparation, and preparation of test portions5.1 Sampling and sample preparationSampling of a lot and preparation of a test sample shall be in accordance with ISO 3082.The size ranges for pellets shall be 50 % - 16,0 mm + 12,5 mm and 50 %
31、 - 12,5 mm + 10,0 mm.The size ranges for lump ores shall be 50 % - 20,0 mm + 16,0 mm and 50 % - 16,0 mm + 10,0 mm.A test sample of at least 2,0 kg, on a dry basis, of the sized material shall be obtained.Oven-dry the test sample to constant mass at 105 C 5 C and cool it to room temperature before pr
32、eparation of the test portions.NOTE Constant mass is achieved when the difference in mass between two subsequent measurements becomes less than 0,05 % of the initial mass of the test sample.5.2 Preparation of test portionCollect each test portion by taking ore particles at random.NOTE Manual methods
33、 of division recommended in ISO 3082, such as riffling, can be applied to obtain the test portions.At least four test portions, each of approximately 500 g ( the mass of 1 particle), shall be prepared from the test sample.Weigh the test portions to the nearest 1 g and register the mass of each test
34、portion on its recipient label.6 Apparatus6.1 GeneralThe test apparatus shall comprise the following:a) ordinary laboratory equipment, such as an oven, hand tools, time-control device, and safety equipment;b) reduction tube assembly;c) furnace, with a system to rotate the reduction tube;d) system to
35、 supply the gases and regulate the flow rates;e) test sieves;f) weighing device.Figure 1 shows an example of the test apparatus.6.2 Reduction tube, without lifters, made of non-scaling, heat-resistant metal to withstand temperatures higher than 760 C and resistant to deformation.The internal diamete
36、r shall be 130 mm 1 mm and its internal length shall be 200 mm. A dust collector shall be connected to the tube to trap any fine particles carried in the gas stream out of the tube during the test.6.3 Furnace, having a heating capacity and temperature control able to reach the test temperature withi
37、n 90 min and to maintain the entire test portion, as well as the gas entering the bed, at 760 C 5 C.2 ISO 2015 All rights reservedBS ISO 11257:2015ISO 11257:2015(E)6.4 Rotation equipment, capable of rotation the reduction tube at a constant rate of 10 r/min 1 r/min.6.5 Gas-supply system, capable of
38、supplying the gases and regulating gas flow rates.6.6 Test sieves, conforming to ISO 3310-1 or ISO 3310-2 and having mesh apertures of the following nominal sizes: 10,0 mm and 3,15 mm.6.7 Weighing device, capable of weighing the test sample and test portions to an accuracy of 0,1 g.7 Test conditions
39、7.1 GeneralVolumes and flow rates of gases used are as measured at a reference temperature of 0 C and at a reference atmospheric pressure of 101,325 kPa (1,013 25 bar).7.2 Reducing gas7.2.1 CompositionThe reducing gas shall consist of the following:CO 36,0 % 1,0 % (volume fraction)CO25,0 % 1,0 % (vo
40、lume fraction)H255,0 % 1,0 % (volume fraction)CH44,0 % 1,0 % (volume fraction)7.2.2 PurityImpurities in the reducing gas shall not exceed the following:O20,1 % (volume fraction)H2O 0,2 % (volume fraction)7.2.3 Flow rateThe flow rate of the reducing gas, during the entire reducing period, shall be ma
41、intained at 13 L/min 0,5 L/min.7.3 Heating and cooling gasNitrogen (N2) shall be used as the heating and cooling gas. Impurities shall not exceed 0,1 % (volume fraction).The flow rate of N2shall be maintained at 10 L/min until the test portion reaches 760 C and at 13 L/min during temperature-equilib
42、ration period. During cooling, it shall be maintained at 10 L/min.7.4 Temperature of the test portionThe temperature of the entire test portion shall be maintained at 760 C 5 C during the entire reducing period and, as such, the reducing gas shall be preheated before entering the test portion. ISO 2
43、015 All rights reserved 3BS ISO 11257:2015ISO 11257:2015(E)8 Procedure8.1 Number of determinations for the testCarry out the test as many times as required by the procedure in Annex A.8.2 ReductionTake, at random, one of the test portions prepared in 5.2 and place it in the reduction tube (6.2).Inse
44、rt the reduction tube into the furnace (6.3). Close the reduction tube, connect the thermocouple, ensuring that its tip is in the middle of the reduction tube, and connect the gas supply system.By means of the rotation equipment (6.4), commence rotation of the reduction tube at 10 r/min 1 r/min.Pass
45、 a flow of N2through the test portion at a rate of at least 10 L/min and immediately commence heating. The heating rate shall be such that the test portion reaches 760 C within 90 min. When the temperature approaches 760 C, increase the flow rate of N2to 13 L/min and continue heating at 760 C 5 C fo
46、r 30 min.DANGER Carbon monoxide, hydrogen, and reducing gas, which contains carbon monoxide and hydrogen, are toxic and explosive, and therefore hazardous. Testing shall be carried out in a well ventilated area or under a hood. Precautions should be taken for the safety of the operator, in accordanc
47、e with the safety codes of each country.Introduce the reducing gas at a flow rate of 13 L/min 0,5 L/min to replace the N2. After 300 min of reduction, stop the flow of the reducing gas, stop the rotation of the reduction tube and cool the reduced test portion to room temperature under N2at a flow ra
48、te of 10 L/min.8.3 SievingRemove all the material carefully from the reduction tube, scraping, if necessary, to remove any material adhering to the tube wall. Remove from the reduced material any free carbon deposited during reduction (a magnet can be used).Determine the mass of the reduced material
49、 (m0) and hand sieve it with care on 10,0 mm and 3,15 mm sieves (6.6). Determine and record the mass of each fraction retained on 10,0 mm (m1) and 3,15 mm (m2) sieves to the nearest 0,1 g. The dry weight of dust trapped in the dust collector, and material lost during sieving, shall be considered to be part of the 3,15 mm fraction.NOTE Equivalent mechanical sieving can be used provided that preliminary test programme is carried out according to ISO 3086, having as referen
