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、37g54g44g3g51g40g53g48g44g54g54g44g50g49g3g40g59g38g40g51g55g3g36g54g3g51g40g53g48g44g55g55g40g39g3g37g60g3g38g50g51g60g53g44g42g43g55g3g47g36g58Licensed Copy: Wang Bin, na, Tue Apr 18 07:54:38 BST 2006, Uncontrolled Copy, (c) BSIBS EN 14945:2005This British Standard was published under the authorit
3、y of the Standards Policy and Strategy Committee on 16 January 2006 BSI 16 January 2006ISBN 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 It supersedes BS 1902-9.3:1998 which is withdrawn.The UK participation in its preparation was ent
4、rusted to Technical Committee RPI/1, Refractories, which has the responsibility to: A 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 docum
5、ent may be found in the BSI Catalogue 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. U
6、sers are responsible for its correct 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 chan
7、ge, and keep UK interests informed; monitor related international and European developments 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
8、 indicates when the document was last issued.Amendments issued since publicationAmd. No. Date CommentsLicensed Copy: Wang Bin, na, Tue Apr 18 07:54:38 BST 2006, Uncontrolled Copy, (c) BSIEUROPEAN STANDARDNORME EUROPENNEEUROPISCHE NORMEN 14945December 2005ICS 81.080English VersionRefractory products
9、and materials - Spectrometric determinationof chromium (VI) in chrome bearing refractories, before and afteruseProduits et matriaux rfractaires - Dtermination parspectromtrie du chrome VI dans des matriauxrfractaires forte teneur en chrome, avant et aprs usageFeuerfeste Erzeugnisse und Werkstoffe -
10、SpektrometrischeBestimmung des Chrom(VI)-Gehaltes in chromhaltigenfeuerfesten Erzeugnissen vor und nach der VerwendungThis European Standard was approved by CEN on 19 September 2005.CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving th
11、is EuropeanStandard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such nationalstandards may be obtained on application to the Central Secretariat or to any CEN member.This European Standard exists in three official versions (Eng
12、lish, 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 Secretariat has the same status as the officialversions.CEN members are the national standards bodies of Austria, Belgium, Cyprus, Czec
13、h 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.EUROPEAN COMMITTEE FOR STANDARDIZATIONCOMIT EUROPEN DE NORMAL
14、ISATIONEUROPISCHES KOMITEE FR NORMUNGManagement Centre: rue de Stassart, 36 B-1050 Brussels 2005 CEN All rights of exploitation in any form and by any means reservedworldwide for CEN national Members.Ref. No. EN 14945:2005: ELicensed Copy: Wang Bin, na, Tue Apr 18 07:54:38 BST 2006, Uncontrolled Cop
15、y, (c) BSIEN 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 Licensed Copy: Wang Bin, na, Tue Apr 18 07:54:38 BST 2006, Uncontrolled Copy, (c)
16、 BSIEN 14945:2005 (E) 3 Foreword This European 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
17、an identical text or by endorsement, at 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 S
18、tandard: Austria, Belgium, Cyprus, Czech 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. Licensed Copy: Wang
19、 Bin, na, Tue Apr 18 07:54:38 BST 2006, Uncontrolled Copy, (c) BSIEN 14945:2005 (E) 4 1 Scope This European Standard describes 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 (conta
20、ining natural chromite, fused grain or co-clinker) and to unfired materials (with refractory cement or chemical bonds) although 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
21、by modifying the dilution factors. 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)
22、applies. EN ISO 3696, Water for analytical laboratory use - Specification and test methods (ISO 3696:1987) 3 Principle Hexavalent 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 (C
23、a, Fe, Na, K, Mg, Zn, Cu, Pb) but not their trivalent counterparts. The chromium (VI) is then determined spectrometrically by 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 exa
24、ct wavelength being given in the test report. NOTE It is recognized that the method does not entail total dissolution of the 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 a
25、nd an inter-laboratory reproducibility of 15 % of content. Should a more accurate assessment of chromium (VI) be required, repeat 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,
26、 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 grinding. 4.6 Magnet. 4.7 Hot plate magnetic stirrer. Licensed Copy: Wang Bin, na, Tue Apr 18 07:54:38 BST 2006, Uncontrolled Copy, (c) BSIEN 14945:2005 (E) 5 5 Reagents 5.1 Ge
27、neral 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 Commercially available reagents with guaranteed concentrations may also be used. 5.2 Alkali
28、ne 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 of use. 5.3 Chromium (VI) stock solution Weigh (0,355 0,005) g of potassium dichromate (K2
29、Cr2O7) 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 (VI) standard solution Using a pipette transfer 10 ml of the chromium (VI) stock solution
30、(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 carbazide solution Dissolve 1 g of 1,5-diphenyl carbazide in 100 ml of propanone (acetone) C3H
31、6O. 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 grinding. Cone and quarter approximately 200 g of the crushed sample. Remove any iron intro
32、duced 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, localized dust extraction used during sample preparation. NOTE 2 Iron contamination from
33、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, as their presence may result in the reduction of chromium (VI) during analysis. NOTE 4 Iro
34、n or steel mortars should not be used for fine grinding to avoid contamination of the sample by metallic iron. Licensed Copy: Wang Bin, na, Tue Apr 18 07:54:38 BST 2006, Uncontrolled Copy, (c) BSIEN 14945:2005 (E) 6 7 Calibration To a series of 7 100 ml volumetric flasks add 0 ml, 2 ml, 5 ml, 10 ml,
35、 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 and al
36、low 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 concentrat
37、ion 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 (5.2). C
38、over 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 cold
39、 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 addition o
40、f 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 colour to
41、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 solut
42、ion 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 alumina
43、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 to 1
44、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. Licensed Copy: Wang Bin, na, Tue Apr 18 07:54:38 BST 2006, Uncontrolled Copy, (c) BSIEN 14945:20
45、05 (E) 7 9 Calculation of results The calibration is for a range of 0 mg/kg to 500 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
46、 equation: vmMCVCrefrefcor= (1) where C is the concentration of chromium (VI) estimated 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 ma
47、ss of sample used, in grams (g). Report the result to the nearest milligram per 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) r
48、esults of the test as concentration of chromium (VI) in mg/kg, including the results 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
49、determination; f) any other factors which may have influenced the result; g) name 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. Licensed Copy: Wang Bin, na, Tue Apr 18 07:54:38 BST 2006, Uncontrolled Copy, (c) BSIBS EN 14945:2005BSI389 Chiswick High RoadLondonW4 4ALBSI British Standards InstitutionBSI is the independent national body responsible for preparing British Standards. It presents the UK view on standards in Europe and at the i
