1、BS ISO 15237:2016Solid mineral fuels Determination of total mercurycontent of coalBSI Standards PublicationWB11885_BSI_StandardCovs_2013_AW.indd 1 15/05/2013 15:06BS ISO 15237:2016 BRITISH STANDARDNational forewordThis British Standard is the UK implementation of ISO 15237:2016. It supersedes BS ISO
2、 15237:2003 which is withdrawn. The UK participation in its preparation was entrusted to TechnicalCommittee PTI/16, Solid mineral fuels.A list of organizations represented on this committee can beobtained on request to its secretary.This publication does not purport to include all the necessaryprovi
3、sions of a contract. Users are responsible for its correctapplication. The British Standards Institution 2016. Published by BSI Standards Limited 2016ISBN 978 0 580 92524 5ICS 73.040Compliance with a British Standard cannot confer immunity fromlegal obligations.This British Standard was published un
4、der the authority of theStandards Policy and Strategy Committee on 30 November 2016.Amendments/Corrigenda issued since publicationDate Text affectedBS ISO 15237:2016 ISO 2016Solid mineral fuels Determination of total mercury content of coalCombustibles minraux solides Dosage du mercure total dans le
5、 charbonINTERNATIONAL STANDARDISO15237Second edition2016-11-15Reference numberISO 15237:2016(E)BS ISO 15237:2016ISO 15237:2016(E)ii ISO 2016 All rights reservedCOPYRIGHT PROTECTED DOCUMENT ISO 2016, Published in SwitzerlandAll rights reserved. Unless otherwise specified, no part of this publication
6、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 below or ISOs member body in the country of t
7、he 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 15237:2016ISO 15237:2016(E)Foreword ivIntroduction v1 Scope . 12 Normative references 13 Terms and definition 14 Principle 15 Reag
8、ents 16 Apparatus . 27 Preparation of sample 38 Oxygen bomb combustion procedure 38.1 General . 38.2 Combustion of coal 39 Preparation of test solution 310 Atomic absorption analysis . 410.1 Calibration 410.2 Analytical procedure 411 Expression of results 512 Precision . 512.1 Repeatability limit 51
9、2.2 Reproducibility critical difference . 513 Test report . 5 ISO 2016 All rights reserved iiiContents PageBS ISO 15237:2016ISO 15237:2016(E)ForewordISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of prepar
10、ing 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 li
11、aison 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 Di
12、rectives, 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
13、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. 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 decl
14、arations 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 a
15、bout ISOs adherence to the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see the following URL: www.iso.org/iso/foreword.html.The committee responsible for this document is ISO/TC 27, Solid mineral fuels, Subcommittee SC 5, Methods of analysis.This second edition
16、 cancels and replaces the first edition (ISO 15237:2003), which has been technically revised. This document incorporates changes related to dated references and other minor items following its systematic review.iv ISO 2016 All rights reservedBS ISO 15237:2016ISO 15237:2016(E)IntroductionMercury occu
17、rs naturally in coal. It is an element that can be released during the combustion process.The determination of the total mercury content of coal cannot be accomplished satisfactorily by traditional ashing and digestion procedures because of the volatility of the element.Quantitive recovery can be ac
18、hieved by strict adherence to the procedure set out in this document.Instrumental methods for a more rapid determination of total mercury content are available. If such a method is to be used, it is important to demonstrate that the method is free from bias, when compared with this reference method
19、and will give levels of repeatability and reproducibility which are the same, or better than, those quoted for the reference method (see Clause 10). ISO 2016 All rights reserved vBS ISO 15237:2016BS ISO 15237:2016Solid mineral fuels Determination of total mercury content of coal1 ScopeThis document
20、specifies a procedure for the determination of the total mercury content of coal.2 Normative referencesThe following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only the edition cited applies.
21、For undated references, the latest edition of the referenced document (including any amendments) applies.ISO 1170, Coal and coke Calculation of analyses to different basesISO 1928, Solid mineral fuels Determination of gross calorific value by the bomb calorimetric method and calculation of net calor
22、ific valueISO 3696, Water for analytical laboratory use Specification and test methodsISO 5068-2, Brown coals and lignites Determination of moisture content Part 2: Indirect gravimetric method for moisture in the analysis sampleISO 5069-2, Brown coals and lignites Principles of sampling Part 2: Samp
23、le preparation for determination of moisture content and for general analysisISO 13909-4, Hard coal and coke Mechanical sampling Part 4: Coal Preparation of test samples3 Terms and definitionNo terms and definitions are defined in this document.ISO and IEC maintain terminological databases for use i
24、n standardization at the following addresses: IEC Electropedia: available at http:/www.electropedia.org/ ISO Online browsing platform: available at http:/www.iso.org/obp4 PrincipleThe sample is burned in an oxygen bomb, the mercury species formed during combustion being absorbed in water. The mercur
25、y species present in the water are reduced by stannous chloride and quantified by flameless cold vapour atomic absorption spectroscopy.It is reported that lithium borohydride (LiBH4) and sodium borohydride (NaBH4) are satisfactory for the reduction instead of stannous chloride; laboratories using th
26、ese reductants should demonstrate that the performance is equivalent to that using stannous chloride.5 ReagentsWARNING Care should be exercised when handling the reagents, many of which are toxic and corrosive.During the analysis, unless otherwise stated, use only reagents of recognized analytical g
27、rade.INTERNATIONAL STANDARD ISO 15237:2016(E) ISO 2016 All rights reserved 1BS ISO 15237:2016ISO 15237:2016(E)5.1 Water, conforming to Grade 1 of ISO 3696.5.2 Oxygen, free from combustible matter and having a purity of at least 99,5 %.5.3 Nitric acid solution, 10 % by volume, prepared by diluting 10
28、0 ml of concentrated nitric acid (relative density 1,42) to 1 litre with water. The 10 % solution shall have a mercury content less than 0,1 g/l.5.4 Mercury standard stock solution, 1 000 g/ml, prepared by dissolving 1,0 g of high purity mercury in 5 ml of 25 % (V/V) nitric acid solution and dilutin
29、g to 1 000 ml.The mercury standard stock solution may also be prepared from commercially available certified mercury solution.Other high purity (99,9 %) mercury salts or oxides may be used with appropriate adjustment of the mass taken.5.5 Mercury standard solution, 0,1 g/ml, prepared by diluting 5,0
30、 ml of mercury standard stock solution (5.4) to 500 ml with water and then diluting 10,0 ml of the intermediate solution to 1 litre with water.This mercury standard solution should be prepared daily.5.6 Potassium permanganate solution, 50 g/l, prepared by dissolving 5 g of potassium permanganate (KM
31、nO4) in water and diluting to 100 ml.The mercury content of the potassium permanganate should be below 0,05 g/g.5.7 Hydroxylammonium chloride solution, 15 g/l, prepared by dissolving 1,5 g of hydroxylammonium chloride (HONH3Cl) in water and diluting to 100 ml.The mercury content of the hydroxylammon
32、ium chloride should be below 0,005 g/g.5.8 Reducing agent, stannous chloride solution, 100 g/l, prepared by dissolving 10 g of stannous chloride dihydrate (SnCl22H2O) in 45 ml of concentrated hydrochloric acid solution (relative density 1,19) and cautiously diluting to 100 ml with water.The mercury
33、content of the stannous chloride dihydrate should be below 0,01 g/g.NOTE See also Note 1 to 10.2 regarding the use of flow injection techniques.6 Apparatus6.1 Balance, capable of weighing to the nearest 0,1 mg.6.2 Oxygen combustion bomb, constructed in accordance with ISO 1928. The ignition wire sha
34、ll be platinum or chromium-nickel alloy. The combustion bomb shall be constructed of materials that are not affected by the combustion process or products. In particular, the combustion bomb shall be constructed of material that is free from mercury. This can be verified by washing the interior surf
35、aces with dilute nitric acid (50 ml, 10 % V/V), and determining the mercury content of the washings. This shall be 0,01 g per bomb. The combustion bomb shall also be designed so that all liquid combustion products can be completely recovered.WARNING The combustion bomb should be inspected regularly
36、for signs of corrosion caused by the strong acid used in the procedure.2 ISO 2016 All rights reservedBS ISO 15237:2016ISO 15237:2016(E)6.3 Silica combustion crucible, to fit oxygen combustion bomb.6.4 Atomic absorption spectrometer, with a flameless cold-vapour mercury analysis system, comprised of
37、either a closed recirculating system or an open one-pass system.7 Preparation of sampleThe test sample is the general analysis test sample prepared in accordance with ISO 5069-2 or ISO 13909-4 as appropriate. Ensure that the moisture content of the sample is in equilibrium with the laboratory atmosp
38、here, exposing it if necessary, in a thin layer for the minimum time required to achieve equilibrium.Before commencing the determination, mix the equilibrated sample for at least 1 min, preferably by mechanical means.If the results are to be calculated other than on the “air-dried” basis (see Clause
39、 11), then, after weighing the test portion, determine the moisture content of a further portion of the test sample by the method described in ISO 5068-2 as appropriate.8 Oxygen bomb combustion procedure8.1 GeneralClean all internal components of the combustion bomb (the body, cap and electrodes) by
40、 immersion in 10 % nitric acid solution for 5 min followed by thorough washing with water before use. Using paper towels, dry the threads on the combustion bomb body and locking ring. Repeat the washing step between each determination.8.2 Combustion of coalWeigh approximately 1 g of test portion, to
41、 the nearest 0,1 mg, into a pre-ignited crucible.Assemble the ignition system using ignition wire and ignition thread.Pipette 10 ml of water into the base of the combustion bomb and assemble.Charge the bomb with oxygen (5.2) to 3 MPa pressure.Place the assembled combustion bomb in the calorimeter ca
42、n containing 2 litres of water and fire using the ignition/firing station. Allow the combustion bomb to stand in the calorimeter can for 10 min before removal.Dry external surfaces of the bomb thoroughly with paper towel, keeping the bomb upright, before carefully venting the bomb gases over a perio
43、d of 2 min.9 Preparation of test solutionDisassemble the combustion bomb and carefully rinse all internal surfaces, including the crucible, with water, collecting all washings in the bomb.Using a disposable syringe, transfer the bomb washings to a 100 ml volumetric flask containing 10 ml of 10 % nit
44、ric acid solution (5.3). Wash the bomb with water, adding the washings to the volumetric flask. Add 0,5 ml of potassium permanganate solution (5.6) and mix. Dilute to volume with water.Carry out a blank determination following exactly the procedure described above but omitting the coal sample. ISO 2
45、016 All rights reserved 3BS ISO 15237:2016ISO 15237:2016(E)In those cases where the design of the bomb precludes a 1 g test portion being used, a suitable smaller quantity should be taken.NOTE The transfer of the bomb washings by syringe is important since it has been shown that the bomb locking rin
46、g in some calorimeters is a source of mercury contamination which is transferred to the threads of the body. If the bomb washings are poured out in these cases, significant mercury contamination results due to contact between washings and the threads on the bomb body. For calorimeter types initially
47、 shown to give no contamination, the transfer by syringe is not necessary. In every analysis, the documentation for this is achieved by the blank determination.10 Atomic absorption analysis10.1 CalibrationPrepare matrix-matched mercury standards of 3,0 g/l, 5,0 g/l and 10,0 g/l by pipetting 3,0 ml,
48、5,0 ml and 10,0 ml aliquot portions of the 0,1 g/ml mercury standard solution (5.5) into 100 ml graduated flasks, adding 10 ml of 10 % nitric acid solution (5.3) and diluting to volume with water. Add potassium permanganate solution (5.6) dropwise to stabilize the solutions until the permanganate co
49、lour persists for 60 s.Measure the absorbance for each matrix-matched solution in accordance with 10.2. For instrument calibration, the absorbance for each matrix-matched solution is plotted against the corresponding concentration. Sample responses are compared with this calibration.NOTE An alternative quantification procedure is the use of standard analyte additions to the final solutions.10.2 Analytical procedureThe calibration solutions prepared in accordance with 10.1, and the test solutions and the blank sol
