1、 Reference number ISO 11534:2006(E) ISO 2006INTERNATIONAL STANDARD ISO 11534 Second edition 2006-11-15 Iron ores Determination of tin Flame atomic absorption spectrometric method Minerais de fer Dosage de ltain Mthode par spectromtrie dabsorption atomique dans la flamme ISO 11534:2006(E) PDF disclai
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5、ts reserved. Unless otherwise specified, 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
6、 requester. ISO copyright office 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 2006 All rights reservedISO 11534:2006(E) ISO 2006 All rights reserved iii Contents Page Foreword iv 1 Scope. 1 2 No
7、rmative references. 1 3 Principle. 1 4 Reagents 2 5 Apparatus 3 6 Sampling and samples. 3 6.1 Laboratory sample 3 6.2 Preparation of predried test samples . 4 7 Procedure 4 7.1 Number of determinations . 4 7.2 Test portion . 4 7.3 Blank test and check test. 4 7.4 Determination 4 7.4.1 Decomposition
8、of the test portion 4 7.4.2 Treatment of the test solution . 5 7.4.3 Adjustment of atomic absorption spectrometer . 5 7.4.4 Atomic absorption measurements 5 7.4.5 Preparation of calibration solutions . 6 8 Expression of results. 6 8.1 Calculation of mass fraction of tin 6 8.2 General treatment of re
9、sults 6 8.2.1 Repeatability and permissible tolerances 6 8.2.2 Determination of the analytical result. 7 8.2.3 Between-laboratories precision 7 8.2.4 Check for trueness . 8 8.2.5 Calculation of final result. 8 8.3 Oxide factor. 9 9 Test report. 9 Annex A (normative) Flowsheet of the procedure for th
10、e acceptance of analytical values for test samples 10 Annex B (informative) Derivation of repeatability and permissible tolerance equations . 11 Annex C (informative) Precision data obtained by international analytical trials . 12 ISO 11534:2006(E) iv ISO 2006 All rights reservedForeword ISO (the In
11、ternational 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 technical committee h
12、as 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 of electrotechnical
13、 standardization. International Standards are 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 bodi
14、es for voting. Publication as an International 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
15、or all such patent rights. ISO 11534 was prepared by Technical Committee ISO/TC 102, Iron ore and direct reduced iron, Subcommittee SC 2, Chemical analysis. This second edition cancels and replaces the first edition (ISO 11534:1998), which has been technically revised. It has been updated to alter t
16、he manner in which the precision data are presented. INTERNATIONAL STANDARD ISO 11534:2006(E) ISO 2006 All rights reserved 1 Iron ores Determination of tin Flame atomic absorption spectrometric method WARNING This International Standard may involve hazardous materials, operations and equipment. This
17、 International Standard does not purport to address all of the safety problems 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 S
18、cope This International Standard specifies a flame atomic absorption spectrometric method for the determination of the mass fraction of tin in iron ores. This method is applicable to mass fractions of tin between 0,001 % and 0,015 % in natural iron ores, iron ore concentrates and agglomerates, inclu
19、ding sinter products. 2 Normative references The following referenced documents are indispensable for the application 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
20、648: Laboratory glassware One-mark pipettes ISO 1042: Laboratory glassware One-mark volumetric flasks ISO 3082: Iron ores Sampling and sample preparation procedures ISO 3696: Water for analytical laboratory use Specification and test methods ISO 7764: Iron ores Preparation of predried test samples f
21、or chemical analysis 3 Principle The test portion is treated with sulfuric acid and hydrofluoric acid in a platinum crucible. The silica is removed by heating and evaporation. The residue is fused in sodium carbonate/sodium tetraborate flux, and the cooled melt is dissolved in hydrochloric acid. Iro
22、n is reduced by ascorbic acid and potassium iodide, followed by extraction of tin with tri-n-octyl phosphine oxide (TOPO) in 4-methyl-2-pentanone (MIBK) solvent. The tin TOPO/MIBK extract is aspirated into a dinitrogen oxide/acetylene flame and the absorbance of tin is measured at a 286,3 nm resonan
23、ce line using a tin hollow-cathode lamp. The absorbance values obtained are compared with those obtained from calibration solutions. ISO 11534:2006(E) 2 ISO 2006 All rights reserved4 Reagents During the analysis, use only reagents of recognized analytical reagent grade, and only water that complies
24、with grade 2 of ISO 3696. 4.1 Sodium carbonate (Na 2 CO 3 ), anhydrous. 4.2 Sodium tetraborate (Na 2 B 4 O 7 ), anhydrous. 4.3 Iron oxide (Fe 2 O 3 ), of minimum purity 99,9 % (mass fraction) and mass fraction of tin 99,5 % (mass fraction) in a platinum crucible (with cover) with 5 ml of hydrochlori
25、c acid (4.4). After cooling, transfer the solution to a 500 ml one-mark volumetric flask, add 200 ml of hydrochloric acid (4.5), and dilute to volume with hydrochloric acid (4.5). 4.14 Tin standard solution, 40 g Sn/ml. Transfer 20 ml of tin standard solution (4.13) to a 100 ml one-mark volumetric f
26、lask, dilute to volume with hydrochloric acid (4.5) and mix. 4.15 Tin standard solution, 10 g Sn/ml. Transfer 5,0 ml of tin standard solution (4.13) to a 100 ml one-mark volumetric flask, dilute to volume with hydrochloric acid (4.5) and mix. ISO 11534:2006(E) ISO 2006 All rights reserved 3 5 Appara
27、tus Ordinary laboratory apparatus, including one-mark pipettes and one-mark volumetric flasks complying with the specifications of ISO 648 and ISO 1042 respectively, and the following. 5.1 Platinum crucible, of capacity 25 ml to 30 ml. 5.2 Platinum rod. 5.3 Muffle furnace, suitable for heating at 1
28、000 C to 1 020 C. 5.4 Atomic absorption spectrometer, equipped with a dinitrogen oxide/acetylene burner. WARNING To avoid possible explosion hazards, follow the manufacturers instructions for igniting and extinguishing the dinitrogen oxide/acetylene flame. Wear tinted safety glasses whenever the fla
29、me is burning. 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 7.4.5) shall be at least 0,13. b) Graph linearity: the slope of the calibration graph covering the top 20
30、 % of the concentration range (expressed as a change in absorbance) shall not be 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 absorbance of the most concentrated calibration solu
31、tion and that of the zero calibration solution, each being calculated from a sufficient number of repetitive measurements, shall be less than 1,5 % and 0,5 %, respectively, of the mean value of the absorbance of the most concentrated calibration solution. The use of a strip chart recorder and/or dig
32、ital readout device is recommended to evaluate criteria a), b) and c) for all subsequent measurements. NOTE Instrument parameters may vary with each instrument. The following parameters were successfully used in several laboratories and they can be used as guidelines. A dinitrogen oxide/acetylene fl
33、ame was used. Hollow cathode lamp, mA 12,5 Wavelength, nm 286,3 Dinitrogen oxide flow rate, l/min 6,6 Acetylene flow rate, l/min 4,5 In systems where the values shown above for gas flow rates do not apply, the ratio of the gas flow rates may still be a useful guideline. 6 Sampling and samples 6.1 La
34、boratory sample For analysis, use a laboratory sample of minus 100 m particle size which has been taken and prepared in accordance with ISO 3082. In the case of ores having significant contents of combined water or oxidizable compounds, use a particle size of minus 160 m. NOTE A guideline on signifi
35、cant contents of combined water and oxidizable compounds is incorporated in ISO 7764. ISO 11534:2006(E) 4 ISO 2006 All rights reserved6.2 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 represen
36、tative of the whole contents of the container. Dry the test sample at 105 C 2 C, as specified in ISO 7764. (This is the predried test sample.) 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.
37、 NOTE The expression “independently” means that the second and any subsequent result is not affected by the previous result(s). For the particular analytical method, this condition implies that the repetition of the procedure is carried out either by the same operator at a different time or by a dif
38、ferent operator including, in either case, appropriate recalibration. 7.2 Test portion Taking several increments, weigh, to the nearest 0,000 2 g, approximately 2 g of the predried test sample obtained in accordance with 6.2. The test portion should be taken and weighed quickly to avoid re-absorptio
39、n of moisture. 7.3 Blank test and check test In 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 the analysis of the ore sample(s) under the same conditions. A predried test sample of the certified reference mat
40、erial 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 sufficiently similar to ensure that, in either case, no significant changes in the analytical procedure will become
41、necessary. Where a certified 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 used are fro
42、m 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 may be used. 7.4 Determination 7.4.1 Decomposition of the test portion Transfer the test portion (7.2) to a crucible (5.
43、1), moisten with a few drops of water, add 2 ml of sulfuric acid (4.9) and 6 ml of hydrofluoric acid (4.7), mix well using a platinum rod (5.2) and wash the rod with water. Using a gas burner, heat the crucible gently at first, then to white fumes, and continue heating until no fumes are observed. P
44、lace the crucible in a muffle furnace (5.3) at 1 000 C to 1 020 C for 30 min. During the first heating, mix the contents periodically to facilitate the digestion of silica. Cool the crucible and remove the residue on the crucible walls using a platinum rod. Add 1,6 g of sodium carbonate (4.1) and 0,
45、8 g of sodium tetraborate (4.2), mix well with a platinum rod, and heat over a Meker ISO 11534:2006(E) ISO 2006 All rights reserved 5 burner for 5 min or until the mixture has partially melted. Add a further 1,6 g of sodium carbonate and 0,8 g of sodium tetraborate and repeat the heating until the f
46、usion is virtually complete, swirling the crucible to remove any residue on its inner walls. Remove from the heat source and swirl until the melt solidifies on the inner walls of the crucible. Place the crucible in a muffle furnace at 1 000 C to 1 020 C for 15 min. Cool and place the crucible in a 2
47、00 ml beaker. Add 50 ml of hydrochloric acid (4.6), cover the beaker with a watch glass and heat at 90 C until dissolution of the melt is complete. NOTE 1 A pressurized air burner or similar, capable of attaining a temperature of 900 C or more, may be used instead of a Meker burner. NOTE 2 The cruci
48、ble may need to be rolled to ensure complete dissolution of the fused melt. Remove the crucible and rinse it. Cool the solution. 7.4.2 Treatment of the test solution Add 20 ml of ascorbic acid solution (4.10) and 4 ml of potassium iodide/ascorbic acid solution (4.11) to the test solution (see 7.4.1)
49、 and mix. Transfer the solution to a 200 ml separating funnel having a mark indicating 100 ml volume. Dilute to 100 ml with water and mix gently. Add 10,0 ml of TOPO/MIBK solution (4.12). Stopper the funnel and shake vigorously for 30 s. Allow the layers to separate. Drain the lower aqueous layer. Drain the organic layer through a dry filter paper into a 25 ml one-mark volumetric flask and stopper it. Reserve the solution for atomic absorption measurement. (This solution is the TOPO/MIBK extract.) 7.4.3 Ad
