1、BSI Standards PublicationBS ISO 15634:2015Iron ores Determinationof chromium content Flame atomic absorptionspectrometric methodBS ISO 15634:2015 BRITISH STANDARDNational forewordThis British Standard is the UK implementation of ISO 15634:2015. Itsupersedes BS ISO 15634:2005 which is withdrawn.The U
2、K 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 necessaryprovisions of a contract. Users are responsible for
3、its correctapplication. The British Standards Institution 2015. Published by BSI StandardsLimited 2015ISBN 978 0 580 88341 5ICS 73.060.10Compliance with a British Standard cannot confer immunity fromlegal obligations.This British Standard was published under the authority of theStandards Policy and
4、Strategy Committee on 31 August 2015.Amendments issued since publicationDate Text affectedBS ISO 15634:2015 ISO 2015Iron ores Determination of chromium content Flame atomic absorption spectrometric methodMinerais de fer Dosage du chrome Mthode par spectromtrie dabsorption atomique dans la flammeINTE
5、RNATIONAL STANDARDISO15634Second edition2015-08-01Reference numberISO 15634:2015(E)BS ISO 15634:2015ISO 15634:2015(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 repro
6、duced 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 ISOs member body in the country of the requester
7、.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 15634:2015ISO 15634:2015(E)Foreword iv1 Scope . 12 Normative references 13 Principle 14 Reagents 15 Apparatus . 26 Sampling and samples 36.1 L
8、aboratory sample . 36.2 Preparation of predried test samples 37 Procedure. 47.1 Number of determinations . 47.2 Test portion 47.3 Blank test and check test 47.4 Determination . 47.4.1 Decomposition of the test portion 47.4.2 Removal of iron . 57.4.3 Treatment of the residue 57.4.4 Preparation of the
9、 calibration solutions 57.4.5 Preparation of the flame setting solution . 67.4.6 Adjustment of the atomic absorption spectrometer. 67.4.7 Atomic absorption measurements . 68 Expression of results 68.1 Calculation of chromium content 68.2 General treatment of results . 78.2.1 Repeatability and permis
10、sible tolerance 78.2.2 Determination of analytical result 78.2.3 Between-laboratories precision . 78.2.4 Check for trueness 88.2.5 Calculation of final result 98.3 Oxide factor for conversion to chromium oxide . 99 Test report . 9Annex A (normative) Flowsheet of the procedure for the acceptance of a
11、nalytical values for test samples 10Annex B (informative) Derivation of repeatability and permissible tolerance equations 11Annex C (informative) Precision data obtained by international analytical trial 12Bibliography .13 ISO 2015 All rights reserved iiiContents PageBS ISO 15634:2015ISO 15634:2015(
12、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. Each member body interested in a subject for which a
13、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 matter
14、s 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 different types of ISO documents should be noted. This docum
15、ent 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 shall not be held responsible for identifying any or all suc
16、h 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 document is information given for the convenience of users and does
17、 not constitute an endorsement.For an explanation on the meaning of ISO specific terms and expressions related to conformity assessment, as well as information about ISOs adherence to the WTO principles in the Technical Barriers to Trade (TBT) see the following URL: Foreword - Supplementary Informat
18、ionThe committee responsible for this document is ISO/TC 102, Iron ore and direct reduced iron, Subcommittee SC 2, Chemical analysis.This second edition cancels and replaces the first edition (ISO 15634:2005), which has been technically revised.iv ISO 2015 All rights reservedBS ISO 15634:2015INTERNA
19、TIONAL STANDARD ISO 15634:2015(E)Iron ores Determination of chromium content Flame atomic absorption spectrometric methodWARNING This International Standard may involve hazardous materials, operations, and equipment. This International Standard does not purport to address all of the safety problems
20、associated with its use. It is the responsibility of the user of this International Standard to establish appropriate health and safety practices and determine the applicability of regulatory limitations prior to use.1 ScopeThis International Standard specifies a flame atomic absorption spectrometri
21、c method for the determination of the chromium content of iron ores.This method is applicable to chromium contents between 0,001 6 % and 0,1 % (mass fractions) in natural iron ores, iron ore concentrates, and agglomerates including sinter products.2 Normative referencesThe following documents, in wh
22、ole or in part, are normatively referenced in this document 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 648, Laboratory glassware Single-v
23、olume pipettesISO 1042, Laboratory glassware One-mark volumetric flasksISO 3082, Iron ores Sampling and sample preparation proceduresISO 3696, Water for analytical laboratory use Specification and test methodsISO 7764, Iron ores Preparation of predried test samples for chemical analysis3 PrincipleTh
24、e test portion is decomposed by treatment with hydrochloric and nitric acids.The major portion of iron in the filtrate is removed by extraction with 4-methylpentan-2-one.The insoluble residue is ignited and the silicon dioxide is removed by evaporation with hydrofluoric and sulfuric acids. The resid
25、ue is fused with a mixture of sodium carbonate and sodium tetraborate, and then dissolved with hydrochloric acid and combined with the main solution.The solution is aspirated into the flame of an atomic absorption spectrometer using a nitrous oxide-acetylene burner.The absorbance values obtained are
26、 compared with those obtained from the calibration solutions.4 ReagentsDuring the analysis, use only reagents of recognized analytical grade.4.1 Water, complying with grade 2 as defined in ISO 3696. ISO 2015 All rights reserved 1BS ISO 15634:2015ISO 15634:2015(E)4.2 Sodium carbonate, (Na2CO3), anhyd
27、rous powder.4.3 Sodium tetraborate, (Na2B4O7), anhydrous powder.4.4 Lithium tetraborate, (Li2B4O7), anhydrous powder.4.5 Hydrochloric acid, 1,16 g/ml to 1,19 g/ml.4.6 Hydrochloric acid, 1,16 g/ml to 1,19 g/ml, diluted 2 + 1.4.7 Hydrochloric acid, 1,16 g/ml to 1,19 g/ml, diluted 1 + 1.4.8 Hydrochlori
28、c acid, 1,16 g/ml to 1,19 g/ml, diluted 2 + 100.4.9 Nitric acid, 1,4 g/ml.4.10 Nitric acid, 1,4 g/ml, diluted 1 + 1.4.11 Hydrofluoric acid, 1,13 g/ml, 40 % (mass fraction) or 1,19 g/ml, 48 % (mass fraction).4.12 Sulfuric acid, 1,84 g/ml.4.13 Sulfuric acid, 1,84 g/ml, diluted 1 + 1.4.14 Methylpentan-
29、2-one, (methyl isobutyl ketone, MIBK).4.15 Chromium standard solution A, 100 g Cr/ml.Dissolve 0,100 0 g of chromium metal purity 99,9 % (mass fraction) (see Note of 4.16) in 20 ml of hydrochloric acid (4.7). After cooling, transfer to a 1 000 ml one-mark volumetric flask quantitatively, dilute to vo
30、lume with water (4.1), and mix.4.16 Chromium standard solution B, 10 g Cr/ml.Transfer 100,0 ml of chromium standard solution A (4.15) to a 1 000 ml one-mark volumetric flask. Dilute to volume with water and mix.NOTE The purity of the metals stated on the certificates does not generally take into acc
31、ount the presence of adsorbed gases like oxygen, carbon monoxide, etc.5 ApparatusOrdinary laboratory apparatus including one-mark pipettes and one-mark volumetric flasks complying with the specifications of ISO 648 and ISO 1042, and the following.5.1 Platinum crucible, of minimum capacity 25 ml.5.2
32、Muffle furnace.5.3 Atomic absorption spectrometer, equipped with a dinitrogen oxide-acetylene burner.WARNING Follow the manufacturers instructions for igniting and extinguishing the dinitrogen oxide-acetylene flame to avoid possible explosion hazards. Wear tinted safety glasses whenever the burner i
33、s in operation.2 ISO 2015 All rights reservedBS ISO 15634:2015ISO 15634:2015(E)The atomic absorption spectrometer used in this method shall meet the following criteria:a) Minimum sensitivity The absorbance of the most concentrated calibration solution (see 7.4.4) is at least 0,3;b) Graph linearity T
34、he slope of the calibration graph covering the top 20 % of the concentration range (expressed as a change in absorbance) is not less than 0,7 of the value of the slope for the bottom 20 % of the concentration range determined in the same way;c) Minimum stability The standard deviation of the absorba
35、nce of the most concentrated calibration solution and that of the zero calibration solution each being calculated from a sufficient number of repetitive measurements are less than 1,5 % and 0,5 %, respectively of the mean value of the absorbance of the most concentrated solution.The use of a strip-c
36、hart recorder and/or digital readout device is recommended to evaluate criteria a), b), and c) and for all subsequent measurements.NOTE Instrument parameters will vary with each instrument. The following parameters were successfully used in several laboratories and they can be used as guidelines: ho
37、llow-cathode lamp 10 mA; wavelength 357,9 nm; dinitrogen oxide flow rate 10 l/min; acetylene flow rate 5 l/min.A dinitrogen oxide-acetylene flame was used.In systems where the values shown above for gas flow rates do not apply, the ratio of the gas flow rates can still be a useful guideline.6 Sampli
38、ng and samples6.1 Laboratory sampleFor analysis, use a laboratory sample of particle size of less than 100 m which has been taken and prepared in accordance with ISO 3082. In the case of ores containing significant contents of combined water or oxidizable compounds, use a particle size of less than
39、160 m.NOTE A guideline on significant contents of combined water and oxidizable compounds is incorporated in ISO 7764.Ensure that the sample has not been pulverized in a nickel/chromium pot.6.2 Preparation of predried test samplesThoroughly mix the laboratory sample and taking multiple increments, e
40、xtract a test sample in such a way that it is representative of the whole contents of the container. Dry the test sample at (105 2) C as specified in ISO 7764 (this is the predried test sample). ISO 2015 All rights reserved 3BS ISO 15634:2015ISO 15634:2015(E)7 Procedure7.1 Number of determinationsCa
41、rry 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 is not affected by the previous result(s). For this particular analytical method, this condition implie
42、s that the repetition of the procedure be carried out either by the same operator at a different time or by a different operator including, in either case, appropriate recalibration.7.2 Test portionTaking several increments, weigh to the nearest 0,000 2 g, approximately 1 g of the predried test samp
43、le obtained in accordance with 6.2.The test portion should be taken and weighed quickly in order to avoid reabsorption of moisture.7.3 Blank test and check testIn each run, one blank test and one analysis of a certified reference material of the same type of ore shall be carried out in parallel with
44、 the analysis of the ore sample(s) under the same conditions. A predried test sample of the certified reference material shall be prepared as specified in 6.2.The certified reference material should be of the same type as the sample to be analysed and the properties of the two materials should be su
45、fficiently similar to ensure that in either case no significant changes in the analytical procedure will become necessary. Where a certificate reference material is not available, a reference material can be used (see 8.2.4).Where the analysis is carried out on several samples at the same time, the
46、blank value can be represented by one test provided that the procedure is the same and the reagents used are from the same reagent bottles.Where the analysis is carried out on several samples of the same type of ore at the same time, the analytical value of one certified reference material can be us
47、ed.7.4 Determination7.4.1 Decomposition of the test portionTransfer the test portion (7.2) to a 250 ml tall-form beaker. Moisten with a few millilitres of water (4.1). Add 25 ml of hydrochloric acid (4.5), cover with a watch-glass, and heat for about 1 h on a hotplate adjusted to give a temperature
48、of 100 C in a test beaker containing a similar volume and depth of sulfuric acid (4.12).If the amount of insoluble residue is high, continue heating on a higher temperature zone of the hotplate without boiling the solution.After heating, the volume of the solution should have decreased to about 10 m
49、l.Add 5 ml of nitric acid (4.9) and 0,2 ml of sulfuric acid (4.13), digest for about 15 min, and evaporate the solution almost to dryness.If the test sample contains a significant content of barium, the addition of sulfuric acid (4.13) should be omitted.Be sure to cover with a watch-glass in order to prevent sublimation of chlorides. During evaporation, shift the glass slightly.4 ISO 2015 All rights reservedBS ISO 15634:2015ISO 15634:2015(E)Add 20 ml of h
