1、BRITISH STANDARDBS EN 14945:2005Refractory products and materials Spectrometric determination of chromium (VI) in chrome bearing refractories, before and after useThe European Standard EN 14945:2005 has the status of a British StandardICS 81.080g49g50g3g38g50g51g60g44g49g42g3g58g44g55g43g50g56g55g3g
2、37g54g44g3g51g40g53g48g44g54g54g44g50g49g3g40g59g38g40g51g55g3g36g54g3g51g40g53g48g44g55g55g40g39g3g37g60g3g38g50g51g60g53g44g42g43g55g3g47g36g58BS EN 14945:2005This British Standard was published under the authority of the Standards Policy and Strategy Committee on 16 January 2006 BSI 16 January 20
3、06ISBN 0 580 47328 7National forewordThis British Standard is the official English language version of EN 14945:2005. It supersedes BS 1902-9.3:1998 which is withdrawn.The UK participation in its preparation was entrusted to Technical Committee RPI/1, Refractories, which has the responsibility to: A
4、 list of organizations represented on this committee can be obtained on request to its secretary.Cross-referencesThe British Standards which implement international or European publications referred to in this document may be found in the BSI Catalogue under the section entitled “International Stand
5、ards 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 correct application. Compliance with a British Standard
6、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 UK interests informed; monitor related international and European develo
7、pments and promulgate them in the UK.Summary of pagesThis document comprises a front cover, an inside front cover, the EN title page, pages 2 to 7 and a back cover.The BSI copyright notice displayed in this document indicates when the document was last issued.Amendments issued since publicationAmd.
8、No. Date CommentsEUROPEAN STANDARDNORME EUROPENNEEUROPISCHE NORMEN 14945December 2005ICS 81.080English VersionRefractory products and materials - Spectrometric determinationof chromium (VI) in chrome bearing refractories, before and afteruseProduits et matriaux rfractaires - Dtermination parspectrom
9、trie du chrome VI dans des matriauxrfractaires forte teneur en chrome, avant et aprs usageFeuerfeste Erzeugnisse und Werkstoffe - SpektrometrischeBestimmung des Chrom(VI)-Gehaltes in chromhaltigenfeuerfesten Erzeugnissen vor und nach der VerwendungThis European Standard was approved by CEN on 19 Sep
10、tember 2005.CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this EuropeanStandard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such nationalstandards may be obt
11、ained on application to the Central Secretariat or to any CEN member.This European Standard exists in three official versions (English, French, German). A version in any other language made by translationunder the responsibility of a CEN member into its own language and notified to the Central Secre
12、tariat has the same status as the officialversions.CEN members are the national standards bodies of Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France,Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portug
13、al, Slovakia,Slovenia, Spain, Sweden, Switzerland and United Kingdom.EUROPEAN COMMITTEE FOR STANDARDIZATIONCOMIT EUROPEN DE NORMALISATIONEUROPISCHES KOMITEE FR NORMUNGManagement Centre: rue de Stassart, 36 B-1050 Brussels 2005 CEN All rights of exploitation in any form and by any means reservedworld
14、wide for CEN national Members.Ref. No. EN 14945:2005: EEN 14945:2005 (E) 2 Contents Page Foreword 3 1 Scope .4 2 Normative references .4 3 Principle.4 4 Apparatus 4 5 Reagents5 6 Sampling5 7 Calibration .6 8 Procedure 6 9 Calculation of results7 10 Test report .7 EN 14945:2005 (E) 3 Foreword This Eu
15、ropean Standard (EN 14945:2005) has been prepared by Technical Committee CEN/TC 187 “Refractory products and materials”, the secretariat of which is held by BSI. This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at
16、the latest by June 2006, and conflicting national standards shall be withdrawn at the latest by June 2006. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Cyprus, Czech
17、 Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom. EN 14945:2005 (E) 4 1 Scope This European Standard describe
18、s a method for the spectrometric determination of chromium (VI) in chrome bearing refractories, before and after use. It is applicable to fired magnesia-chrome products (containing natural chromite, fused grain or co-clinker) and to unfired materials (with refractory cement or chemical bonds) althou
19、gh it is not to be restricted to these types of refractory. The method is applicable to concentrations up to 500 mg/kg of chromium (VI). This range may be extended or reduced by modifying the dilution factors. 2 Normative references The following referenced documents are indispensable for the applic
20、ation 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. EN ISO 3696, Water for analytical laboratory use - Specification and test methods (ISO 3696:1987) 3 Principle Hexava
21、lent chromium is extracted from the sample using a solution of 2 % (w/v) NaOH / 3 % (w/v) Na2CO3which dissolves the common hexavalent chromium compounds potentially present (Ca, Fe, Na, K, Mg, Zn, Cu, Pb) but not their trivalent counterparts. The chromium (VI) is then determined spectrometrically by
22、 reaction with 1,5 - diphenyl carbazide which forms a red-violet chromium complex. The absorbance of the complex is measured at a wavelength between 540 nm and 550 nm, the exact wavelength being given in the test report. NOTE It is recognized that the method does not entail total dissolution of the
23、test sample and hence not all the chromium (VI) may be taken into solution. Trials have indicated that the method yields a minimum of 80 % of the total chromium (VI) present and an inter-laboratory reproducibility of 15 % of content. Should a more accurate assessment of chromium (VI) be required, re
24、peat leachings can be carried out. 4 Apparatus 4.1 Analytical balance, capable of being read to 0,000 5 g. 4.2 Laboratory volumetric glassware, grade A. 4.3 Spectrophotometer, suitable for use in the 540 nm to 550 nm wavelength range. 4.4 Jaw crusher, for crushing bulk samples. 4.5 Device for fine g
25、rinding. 4.6 Magnet. 4.7 Hot plate magnetic stirrer. EN 14945:2005 (E) 5 5 Reagents 5.1 General Use only reagents of recognized analytical grade and only distilled or deionized water with an electrical conductivity less than 2 S/cm, or conforming to the requirements of Grade 3 of EN ISO 3696. NOTE C
26、ommercially available reagents with guaranteed concentrations may also be used. 5.2 Alkaline extraction solution Dissolve 30 g sodium carbonate (Na2CO3) and 20 g sodium hydroxide pellets (NaOH) in water and dilute to volume in a 1 l volumetric flask. Mix thoroughly. Prepare this solution on the day
27、of use. 5.3 Chromium (VI) stock solution Weigh (0,355 0,005) g of potassium dichromate (K2Cr2O7) dried at (110 10) C and dissolve in approximately 200 ml of water in a 500 ml volumetric flask. Dilute to volume. This solution is stable indefinitely and contains (250 4) mg/l of chromium. 5.4 Chromium
28、(VI) standard solution Using a pipette transfer 10 ml of the chromium (VI) stock solution (see 5.3) to a 500 ml volumetric flask and dilute to volume with water. This solution contains 5 mg/l of chromium. Prepare this solution on the day of use. CAUTION Do not pipette by mouth. 5.5 1,5-Diphenyl carb
29、azide solution Dissolve 1 g of 1,5-diphenyl carbazide in 100 ml of propanone (acetone) C3H6O. Acidify with one drop of glacial acetic acid. Prepare this solution on the day of use. 5.6 1+1 Sulphuric acid (V/V) 6 Sampling Using a Jaw crusher (4.4), reduce the bulk sample to a size suitable for fine g
30、rinding. Cone and quarter approximately 200 g of the crushed sample. Remove any iron introduced from the jaw crusher using a magnet. Fine grind the sample to reduce its particle size so that approximately 90 % is less than 125 m. NOTE 1 Dust masks and skin protection should be worn and, if possible,
31、 localized dust extraction used during sample preparation. NOTE 2 Iron contamination from jaw crushing could potentially cause reduction of chromium (VI) during the analysis if not removed. NOTE 3 The removal of any metal or slag adhering to the sample by using a chisel or dry cutting is advisable,
32、as their presence may result in the reduction of chromium (VI) during analysis. NOTE 4 Iron or steel mortars should not be used for fine grinding to avoid contamination of the sample by metallic iron. EN 14945:2005 (E) 6 7 Calibration To a series of 7 100 ml volumetric flasks add 0 ml, 2 ml, 5 ml, 1
33、0 ml, 15 ml, 20 ml, and 25 ml of chromium (VI) standard solution (5.4). Add sufficient water to each flask to bring the volume to approximately 50 ml. Acidify each with 5 drops of sulphuric acid (5.6). Allow to cool. Add 10 ml of 1,5-diphenyl carbazide solution (5.5) and dilute to 100 ml. Mix well a
34、nd allow to stand for 5 min for the colour to develop fully, and measure within a further 10 min. Measure the absorbance between 540 nm and 550 nm against water in 10 mm glass cells. Plot the absorbance against chromium (VI) concentration of the above solutions. The resulting graph will give a conce
35、ntration range of 0 mg/kg to 500 mg/kg chromium (VI) when using the procedure described in Clause 8. 8 Procedure Weigh (5 0,1) g of the fine ground sample to the nearest 0,005 g after drying at (110 + 10) C. Transfer into a 600 ml beaker and add 200 ml of the boiling alkaline extraction solution (5.
36、2). Cover the beaker with a watch glass and boil with constant stirring for 30 min using a hot plate magnetic stirrer (to keep the sample in suspension). Do not allow it to evaporate to dryness. Allow to cool to ambient temperature. Filter the extract through a coarse filter paper1), pre-washed with
37、 cold extraction solution (5.2), into a 500 ml volumetric flask. Wash the residue twice with 50 ml aliquots of the extraction solution followed by water to a total volume of about 400 ml. Dilute to 500 ml with water. Pipette a 25 ml aliquot portion into a 250 ml beaker. Acidify by the dropwise addit
38、ion of sulphuric acid (5.6), stirring until the evolution of carbon dioxide ceases, then add a further 5 drops of sulphuric acid. Allow to cool to ambient temperature, then transfer to a 100 ml volumetric flask, add 10 ml of 1,5-diphenyl carbazide solution (5.5) and dilute to 100 ml. Allow the colou
39、r to develop for 5 min and measure the absorbance within a further 10 min at the wavelength used for the calibration (see Clause 7) using water in the reference cell and 10 mm glass cells. Do not allow to stand longer than 15 min after the addition of the 1,5 diphenyl carbazide as the colour of the
40、solution can be affected. If the filtrate is discoloured or turbid, take another aliquot portion omitting the 1,5-diphenyl carbazide solution and measure its absorbance as a correction. Estimate the concentration of chromium (VI) from the calibration graph described in Clause 7. NOTE 1 With high alu
41、mina materials, cloudiness may occur on acidification or after addition of 1,5-diphenyl carbazide solution. In the first case, the cloudiness may disappear after agitation and in the second, may be removed by the addition of a few further drops of sulphuric acid. NOTE 2 The range can be extended up
42、to 1 250 mg/kg by using a 10 ml aliquot of extraction filtrate. NOTE 3 The presence of organic species in the test sample may interfere with the method. 1)A Whatman No.40 filter paper has been found suitable. EN 14945:2005 (E) 7 9 Calculation of results The calibration is for a range of 0 mg/kg to 5
43、00 mg/kg based on a 5 g sample and the method as described. Allowing for variation in sample mass and different aliquots being taken, the concentration, Ccor, of chromium (VI), in milligrams per kilogram, is given by the equation: vmMCVCrefrefcor= (1) where C is the concentration of chromium (VI) es
44、timated from the graph, in milligrams per kilogramme (mg/kg); Vref is the reference volume, in millilitres (ml); Mrefis the reference mass, in grams (g); v is the volume of aliquot taken, in millilitres (ml); m is the mass of sample used, in grams (g). Report the result to the nearest milligram per
45、kilogram (mg/kg). 10 Test report The test report shall contain the following information: a) all information necessary for identification of the sample tested; b) reference to this European Standard (EN 14945:2005); c) results of the test as concentration of chromium (VI) in mg/kg, including the res
46、ults of the individual determinations (if appropriate) and their mean, calculated in accordance with Clause 9; d) whether a single or duplicate determination was carried out; e) wavelength used in the spectrophotometric determination; f) any other factors which may have influenced the result; g) nam
47、e of the testing establishment; h) any deviations from the procedure specified; i) any unusual features (anomalies) observed during the test; j) date of the test. BS EN 14945:2005BSI389 Chiswick High RoadLondonW4 4ALBSI British Standards InstitutionBSI is the independent national body responsible fo
48、r preparing British Standards. It presents the UK view on standards in Europe and at the international level. It is incorporated by Royal Charter.RevisionsBritish Standards are updated by amendment or revision. Users of British Standards should make sure that they possess the latest amendments or ed
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