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1、BRITISH STANDARD BS ISO 15238:2003 Solid mineral fuels Determination of total cadmium content of coal ICS 73.040 ? Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 06:46:18 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS ISO 15238:2003 This British Standard was published under the authority of t
2、he Standards Policy and Strategy Committee on 5 December 2003 BSI 5 December 2003 ISBN 0 580 43016 2 National foreword This British Standard reproduces verbatim ISO 15238:2003 and implements it as the UK national standard. The UK participation in its preparation was entrusted to Technical Committee
3、PTI/16, Solid mineral fuels, which has the responsibility to: A list of organizations represented on this committee can be obtained on request to its secretary. Cross-references The British Standards which implement international publications referred to in this document may be found in the BSI Cata
4、logue under the section entitled “International Standards Correspondence Index”, or by using the “Search” facility of the BSI Electronic Catalogue or of British Standards Online. This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its co
5、rrect application. Compliance with a British Standard does not of itself confer immunity from legal obligations. aid enquirers to understand the text; present to the responsible international/European committee any enquiries on the interpretation, or proposals for change, and keep the UK interests i
6、nformed; monitor related international and European developments and promulgate them in the UK. Summary of pages This document comprises a front cover, an inside front cover, the ISO title page, pages ii to iv, pages 1 to 6, an inside back cover and a back cover. The BSI copyright notice displayed i
7、n this document indicates when the document was last issued. Amendments issued since publication Amd. No. DateComments Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 06:46:18 GMT+00:00 2006, Uncontrolled Copy, (c) BSI Reference number ISO 15238:2003(E) INTERNATIONAL STANDARD ISO 15238 First
8、edition 2003-12-01 Solid mineral fuels Determination of total cadmium content of coal Combustibles minraux solides Dosage du cadmium total dans le charbon BS ISO 15238:2003 Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 06:46:18 GMT+00:00 2006, Uncontrolled Copy, (c) BSI DPlcsid Fremia ihTs
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14、ernational 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 ha
15、s 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
16、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 bodie
17、s 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 o
18、r all such patent rights. ISO 15238 was prepared by Technical Committee ISO/TC 27, Solid mineral fuels, Subcommittee SC 5, Methods of analysis. BS ISO 15238:2003 Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 06:46:18 GMT+00:00 2006, Uncontrolled Copy, (c) BSI iv Introduction Cadmium occurs
19、naturally in coal. It is an element that can potentially be released during the combustion process. Quantitative recovery can be achieved by strict adherence to the procedure set out in this International Standard. The method may also be suitable for other elements, including lead and arsenic, altho
20、ugh the choice of matrix modifier may vary. BS ISO 15238:2003 Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 06:46:18 GMT+00:00 2006, Uncontrolled Copy, (c) BSI INTENRATIONAL TSANDADR IS:83251 O3002(E) I SO 3002 All irhgts seredevr 1 Solid mineral fuels Determination of total cadmium content
21、 of coal 1 Scope This International Standard specifies a procedure for the determination of the total cadmium content of coal. This procedure has not been validated with coals that spontaneously ignite. Prior to use with such sample types, users should validate the method. 2 Normative references The
22、 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 331, Coal Determination of moisture in the analy
23、sis sample Direct gravimetric method ISO 1170, Coal and coke Calculation of analyses to different bases ISO 3696, Water for analytical laboratory use Specifications and test methods ISO 5068, Brown coals and lignites Determination of moisture content Indirect gravimetric method ISO 5069-2, Brown coa
24、ls and lignites Principles of sampling Part 2: Sample preparation for determination of moisture content and for general analysis ISO 13909-2, Hard coal and coke Mechanical sampling Part 2: Coal Sampling from moving streams 3 Principle The coal sample is ashed, followed by dissolution of the ash in a
25、 mixture of hydrochloric, nitric and hydrofluoric acids. The cadmium species present are quantified by graphite furnace atomic absorption spectroscopy. 4 Reagents WARNING Care should be exercised when handling the reagents, many of which are toxic and corrosive. During the analysis, unless otherwise
26、 stated, use only reagents of recognized analytical grade. 4.1 Water, conforming to the requirements of Grade 1 of ISO 3696. 4.2 Aqua regia solution. Mix 1 part by volume of concentrated nitric acid solution (relative density 1,42), 3 parts of concentrated hydrochloric acid solution (relative densit
27、y 1,19), and 1 part water. BS ISO 15238:2003 1 Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 06:46:18 GMT+00:00 2006, Uncontrolled Copy, (c) BSI ISO 15238:2003(E) 2 I SO 3002 All irhgts seredevr 4.3 Concentrated hydrofluoric acid solution (relative density 1,15). WARNING Hydrofluoric acid i
28、s an extremely aggressive chemical which shall be handled with care. 4.4 Boric acid solution, saturated. Dissolve 60 g of boric acid in 1 litre of hot water, cool and allow to stand for three days before decanting the clear solution. 4.5 Cadmium standard stock solution, 10 g/ml. Prepare the stock so
29、lution from a high purity metal oxide or salt, having a purity greater than 99,9 %. Dilute to volume with 1 % (V/V) nitric acid solution. NOTE The cadmium standard stock solution may also be prepared from commercially available certified cadmium solution. 4.6 Cadmium standard solution, 0,1 g/ml. Dil
30、ute 10,0 ml of cadmium standard stock solution (4.5) to 1,0 litre with 1 % (V/V) nitric acid solution. 5 Apparatus 5.1 Balance, capable of weighing to the nearest 0,1 mg. 5.2 Silica or platinum combustion crucible (45 35 14 mm). 5.3 Muffle furnace, with a temperature control. 5.4 Plastics bottles, m
31、ade of high density polyethylene (HDPE) or fluorinated ethylene propylene (FEP), of 125 ml capacity, with screw-cap lids, capable of withstanding 130 C when sealed and containing liquid. 5.5 Volumetric flasks, made of high density polyethylene (HDPE) or fluorinated ethylene propylene (FEP), of 100 m
32、l capacity. 5.6 Boiling-water bath. 5.7 Graphite-furnace atomic absorption spectrometer, with background correction. 6 Preparation of sample The test sample is the general analysis test sample prepared in accordance with ISO 5069-2 or ISO 13909-2 as appropriate. Ensure that the moisture content of t
33、he sample is in equilibrium with the laboratory atmosphere, 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 ca
34、lculated other than on the “air-dried” basis (see Clause 8), then, after weighing the test portion, determine the moisture content of a further portion of the test sample by the method described in ISO 331 or ISO 5068 as appropriate. 7 Procedure 7.1 Ashing of coal sample Weigh, to the nearest 0,1 mg
35、, the amount of sample necessary to obtain a minimum of 0,2 g ash in one or more open 50 ml silica combustion crucibles (5.2). The coal layer in the crucible shall not exceed a thickness of 0,15 g/cm2. Place the crucibles in a cold muffle furnace (5.3), set to attain (450 10) C in about 1 h, and BS
36、ISO 15238:2003 2 Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 06:46:18 GMT+00:00 2006, Uncontrolled Copy, (c) BSI ISO 15238:2003(E) I SO 3002 All irhgts seredevr 3 maintain at that temperature for a further 2 h. After cooling and weighing, calculate the percentage of ash in the coal. Caref
37、ully mix the ash in the crucibles before transferring it to a sample bottle. NOTE The ashing time of 3 h is a minimum. Ashing overnight (18 h) is allowed. 7.2 Preparation of test solution Place approximately 0,2 g ( 0,1 mg) of ash in a 125 ml plastics bottle (5.4). Add 3 ml of aqua regia (4.2), 5 ml
38、 of concentrated hydrofluoric acid solution (4.3), and tighten the screw cap. Place the bottle on a boiling water bath for 2 h. Remove the bottle and allow it to cool to ambient temperature, cautiously open, then add 50 ml of saturated boric acid solution (4.4). Warm again for approximately 1 h; if
39、a residue remains at this stage it may be ignored. Remove the bottle from the water bath and cool again to ambient temperature before transferring the solution quantitatively to a 100 ml plastics volumetric flask, and diluting to 100 ml with water. Care should be exercised when adding the acid mixtu
40、re to the ash since the 450 C ashing temperature may not have decomposed all carbonates present in the coal. NOTE 1 If desired, it is permitted to prepare the solutions gravimetrically, adjusting the calculations in the appropriate manner. NOTE 2 As an alternative method for the dissolution of the p
41、repared ash, microwave dissolution or acid dissolution in a pressurized vessel can be used, if quantitative recovery of cadmium can be demonstrated. 7.3 Preparation of blank solution Prepare a blank solution by following exactly the dissolution procedure described above (7.2) but omitting the coal (
42、ash) sample. 7.4 Graphite-furnace atomic absorption analysis 7.4.1 Calibration Prepare standards by diluting aliquot portions of the cadmium standard stock solution (4.5), 3 ml of aqua regia solution (4.2), 5 ml of concentrated hydrofluoric acid solution (4.3) and 50 ml of saturated boric acid solut
43、ion (4.4) to 100 ml with water. Standards containing 0,0, 1,0, 2,5 and 5,0 g/l have been found suitable. The standards used should be verified for each instrument. 7.4.2 Measurement of standards Measure the absorbance of each standard solution using the graphite-furnace atomic absorption spectromete
44、r (5.7). Plot the corresponding absorbance response for each matrix-matched standard against concentration, producing a calibration curve for the instrument. Sample responses are then compared directly with the calibration. The performance of the instrument shall be verified by the analysis of certi
45、fied reference materials. NOTE 1 No additional matrix modifier is used for cadmium determination and the instrument parameters allow for this by using a low char temperature. NOTE 2 An alternative quantification procedure is the use of standard analyte additions to the final solution. 7.4.3 Measurem
46、ent of test solution Repeat the procedure described in 7.4.2 for the test solution (7.2). Determine the cadmium concentration in the test solution using the calibration graph (7.4.2). BS ISO 15238:2003 3 Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 06:46:18 GMT+00:00 2006, Uncontrolled Cop
47、y, (c) BSI ISO 15238:2003(E) 4 I SO 3002 All irhgts seredevr 7.4.4 Measurement of blank solution Repeat the procedure described in 7.4.2 for the blank (7.3). Determine the cadmium concentration in the blank solution using the calibration graph (7.4.2) 8 Expression of results 8.1 Ash content Calculat
48、e the ash content, A, as a percentage by mass of the coal sample, using the equation: () () ca A ba 100 mm mm = where ma is the mass of the ashing combustion crucible; mb is the mass of the ashing combustion crucible plus coal before ashing; mc is the mass of the ashing combustion crucible plus coal
49、 after ashing. 8.2 Cadmium content Calculate the cadmium content, Cd, in ng/g, in the coal test sample using the equation: () tb CdA 1000 1000 m = where A is the ash content of the sample as analysed, in percentage by mass; t is the cadmium concentration of the test solution, in g/l; b is the cadmium concentration of the blank solution, in g/l; m is the mass of the sample as analysed, in grams. Report the r