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1、 Reference number ISO 15634:2005(E) ISO 2005 INTERNATIONAL STANDARD ISO 15634 First edition 2005-05-15 Iron ores Determination of chromium content Flame atomic absorption spectrometric method Minerais de fer Dosage du chrome Mthode par spectromtrie dabsorption atomique dans la flamme Copyright Inter
2、national Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/20/2007 03:29:22 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 15634:2005(E) PDF disclaimer This PDF file may contain emb
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5、 were optimized for printing. Every care has been taken to ensure that the file is suitable for use by ISO member bodies. In the unlikely event that a problem relating to it is found, please inform the Central Secretariat at the address given below. ISO 2005 All rights reserved. Unless otherwise spe
6、cified, no part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or ISOs member body in the country of the requester. ISO copyright office
7、Case postale 56 CH-1211 Geneva 20 Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail copyrightiso.org Web www.iso.org Published in Switzerland ii ISO 2005 All rights reserved Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Stan
8、dards 1/9972545001 Not for Resale, 04/20/2007 03:29:22 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 15634:2005(E) ISO 2005 All rights reserved iii Contents Page Forewordiv 1 Scope1 2 Normative references .1 3 Principle.1 4 Reagents2 5 Apparatus.2 6 Sampling and sampl
9、es.3 6.1 Laboratory sample3 6.2 Preparation of predried test samples .3 7 Procedure.4 7.1 Number of determinations .4 7.2 Test portion .4 7.3 Blank test and check test.4 7.4 Determination4 7.4.1 Decomposition of the test portion 4 7.4.2 Removal of iron.5 7.4.3 Treatment of the residue5 7.4.4 Prepara
10、tion of the calibration solutions.5 7.4.5 Preparation of the flame setting solution.6 7.4.6 Adjustment of the atomic absorption spectrometer .6 7.4.7 Atomic absorption measurements6 8 Expression of results6 8.1 Calculation of chromium content6 8.2 General treatment of results7 8.2.1 Repeatability an
11、d permissible tolerance7 8.2.2 Determination of analytical result .7 8.2.3 Between-laboratories precision 7 8.2.4 Check for trueness8 8.2.5 Calculation of final result.8 8.3 Oxide factor for conversion to chromium oxide9 9 Test report9 Annex A (normative) Flowsheet of the procedure for the acceptanc
12、e of analytical values for test samples10 Annex B (informative) Derivation of repeatability and permissible tolerance equations .11 Annex C (informative) Precision data obtained by international analytical trials12 Bibliography .13 Copyright International Organization for Standardization Provided by
13、 IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/20/2007 03:29:22 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 15634:2005(E) iv ISO 2005 All rights reserved Foreword ISO (the International Organization for Standardization)
14、 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 technical committee has been established has the right to be repre
15、sented 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 of electrotechnical standardization. International Standards are
16、 drafted in accordance with the rules given in the ISO/IEC Directives, Part 2. The main task of technical committees is to prepare International Standards. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an Internationa
17、l Standard requires approval by at least 75 % of the member bodies casting a vote. 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 such patent rights. ISO 15634 was prep
18、ared by Technical Committee ISO/TC 102, Iron ore and direct reduced iron, Subcommittee SC 2, Chemical analysis. This first edition of ISO 15634, together with ISO 15633, cancels and replaces ISO 9685:1991, which has been technically revised. Copyright International Organization for Standardization P
19、rovided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/20/2007 03:29:22 MDTNo reproduction or networking permitted without license from IHS -,-,- INTERNATIONAL STANDARD ISO 15634:2005(E) ISO 2005 All rights reserved 1 Iron ores Determination of chromi
20、um content Flame atomic absorption spectrometric method WARNING This International Standard may involve hazardous materials, operations and equipment. This International Standard does not purport to address all of the safety problems associated with its use. It is the responsibility of the user of t
21、his International Standard to establish appropriate health and safety practices and determine the applicability of regulatory limitations prior to use. 1 Scope This International Standard specifies a flame atomic absorption spectrometric method for the determination of the chromium content of iron o
22、res. 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 references The following referenced documents are indispensable for the application of this document.
23、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 One-mark pipettes ISO 1042, Laboratory glassware One-mark volumetric flasks ISO 3082, Iron ores Sampling and s
24、ample preparation procedures ISO 3696, Water for analytical laboratory use Specification and test methods ISO 7764, Iron ores Preparation of predried test samples for chemical analysis 3 Principle The test portion is decomposed by treatment with hydrochloric and nitric acids. The major portion of ir
25、on 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 residue is fused with a mixture of sodium carbonate and sodium tetraborate, and then dissolved with hydr
26、ochloric 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 compared with those obtained from the calibration solutions. Copyright International Organizatio
27、n for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/20/2007 03:29:22 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 15634:2005(E) 2 ISO 2005 All rights reserved 4 Reagents During the analysis, u
28、se only reagents of recognized analytical grade. 4.1 Water, complying with grade 2 as defined in ISO 3696. 4.2 Sodium carbonate, (Na2CO3), anhydrous powder. 4.3 Sodium tetraborate, (Na2B4O7), anhydrous powder. 4.4 Lithium tetraborate, (Li2B4O7), anhydrous powder. 4.5 Hydrochloric acid, 1,16 g/ml to
29、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 Hydrochloric 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/
30、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-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
31、 fraction), (see Note to 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 volume 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
32、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 account the presence of adsorbed gases like oxygen, carbon monoxide, etc. 5 Apparatus Ordinary laboratory apparatus, including one-mark pipet
33、tes 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 Muffle furnace. 5.3 Atomic absorption spectrometer, equipped with a dinitrogen oxide-acetylene burner. WARNING Follow the manufacture
34、rs instructions for igniting and extinguishing the dinitrogen oxide-acetylene flame to avoid possible explosion hazards. Wear tinted safety glasses whenever the burner is in operation. Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Techn
35、ical Standards 1/9972545001 Not for Resale, 04/20/2007 03:29:22 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 15634:2005(E) ISO 2005 All rights reserved 3 The atomic absorption spectrometer used in this method shall meet the following criteria: a) Minimum sensitivity
36、the absorbance of the most concentrated calibration solution (see 7.4.4) is at least 0,3; b) Graph linearity the 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
37、 the concentration range determined in the same way; c) Minimum stability the standard deviation of the absorbance 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 % a
38、nd 0,5 % respectively of the mean value of the absorbance of the most concentrated solution. The use of a strip-chart 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 instrumen
39、t. The following parameters were successfully used in several laboratories and they can be used as guidelines: hollow-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 s
40、hown above for gas flow rates do not apply, the ratio of the gas flow rates can still be a useful guideline. 6 Sampling and samples 6.1 Laboratory sample For 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 ca
41、se of ores containing significant contents of combined water or oxidizable compounds, use a particle size of less than 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/ch
42、romium pot. 6.2 Preparation of predried test samples Thoroughly mix the laboratory sample and, taking multiple increments, extract 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 pred
43、ried test sample.) Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/20/2007 03:29:22 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 15634:2005(E) 4 ISO 2005
44、 All rights reserved 7 Procedure 7.1 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 is not affected by the previous resul
45、t(s). For this particular analytical method, this condition implies 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 portion Taking several increments, weigh,
46、to the nearest 0,000 2 g, approximately 1 g of the predried test sample 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 test In each run, one blank test and one analysis of a certified referen
47、ce material of the same type of ore shall be carried out in parallel with 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
48、sample to be analysed and the properties of the two materials should be sufficiently 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 may be used (see 8.2.4). 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 use