1、ICS 75.160.10Prfung fester Brennstoffe Bestimmung des FluorgehaltesIn keeping with current practice in standards published by the International Organization for Standardization(ISO), a comma has been used throughout as the decimal marker.Ref. No. DIN 51723 : 2002-06English price group 07 Sales No. 0
2、00701.03DEUTSCHE NORM June 200251723 No part of this translation may be reproduced without the prior permission ofDIN Deutsches Institut fr Normung e.V., Berlin. Beuth Verlag GmbH, 10772 Berlin, Germany,has the exclusive right of sale for German Standards (DIN-Normen).Translation by DIN-Sprachendien
3、st.In case of doubt, the German-language original should be consulted as the authoritative text.Determinining the fluorine content of solid fuelsContinued on pages 2 to 4.ForewordThis standard has been prepared by Technical Committee Prfung fester Brennstoffe of the Normen-ausschuss Materialprfung (
4、Material Testing Standards Committee).This standard specifies two digestion methods for dissolving bound fluorine in the fuel. Of the methods ofdetermining the fluoride content (e.g. using a fluorine ion selective electrode or ion chromatography), thelatter is described in this standard.AmendmentsTh
5、is standard differs from the May 1988 edition as follows:a) digestion by steam distillation has been replaced by digestion in an oxygen bomb;b) the fluorine content is now to be by ion chromatography;c) the limit of determination has been reduced from 0,004% to 0,002%;d) the standard has been editor
6、ially revised.Previous editionDIN 51723: 1988-05.1 ScopeThis standard specifies a method of determining the fluorine contents of hard coal, coke, brown coal, lignite,briquettes and lumpwood charcoal by ion chromatography. It is applicable in cases where the fluorinecontent is 0,002% (m/m) or greater
7、.SupersedesMay 1988 edition.Page 2DIN 51723 : 2002-062 Normative referencesThis standard incorporates, by dated or undated reference, provisions from other publications. These norma-tive references are cited at the appropriate places in the text, and the titles of the publications are listed below.F
8、or dated references, subsequent amendments to or revisions of any of these publications apply to thisstandard only when incorporated in it by amendment or revision. For undated references, the latest edition ofthe publication referred to applies.DIN 51701-2 Sampling of solid fuels ProcedureDIN 51701
9、-3 Sampling of solid fuels Sample preparationDIN 51724-1 Determination of total sulfur in solid fuelsDIN EN ISO 10304-1 Water quality Determination of dissolved fluoride, chloride, nitrite, orthophosphate,bromide, nitrate and sulfate ions, using liquid chromatography of ions Method forwater with low
10、 contamination (ISO 10304-1 : 1992)3 DesignationDesignation of method A for determining the fluorine content of solid fuels as specified in this standard:Method DIN 51723 A4 Sampling and sample preparationSampling and sample preparation shall be performed as described in DIN 51701-2 and DIN 51701-3.
11、5 Determination of fluorine content by pyrohydrolysis (method A)5.1 PrincipleThe gases formed when a sample is burnt in a moist oxygen stream are collected in a fluoride absorption flask.The endpoint is determined by ion chromatography.5.2 ApparatusThe following equipment shall be used.a) DIN 51724-
12、1 combustion tube, of silica glass, absorption flask and headpiece.b) Porcelain crucible, with eyelet.c) DIN 51724-1 quartz rod, with iron piece.d) Magnet.e) Electrically heated tubular furnace, about 300 mm long, capable of being heated to 1 300 C andmaintained at 1 250 C.f) Oxygen inlet, consistin
13、g of a silicone stopper with hole and glass rod.g) Ion chromatograph.5.3 ReagentsOnly analytical grade reagents and fully demineralized water shall be used. Unless otherwise stated, solutionsare aqueous solutions.The following reagents shall be used.a) Oxygen, at least 99,5% (V/V).b) Combustion aid
14、(e.g. fluoride-free spectral coal).c) Granulated iron(III) phosphate.d) 2mol/l sodium hydroxide solution, NaOH.5.4 ProcedureAdjust the temperature in the combustion zone of the furnace to (1 250 t 25) C. Introduce the combustion tubeinto the furnace, ensuring that the projecting perpendicular part i
15、s as near the furnace as possible to preventcombustion gases condensing in it. Pass the oxygen at ambient temperature through a gas wash bottle filledwith water to load it with water vapour and adjust the flowrate to 60 l/h. Depending on fluorine content, weigh50 mg to 1 000 mg of sample to an accur
16、acy of 0,1 mg into a porcelain crucible. If the ash content is more than30%, cover the sample with 0,1 g to 0,2 g of fluoride-free spectral coal to ensure uniform combustion, thencover the sample with about 200 mg of iron(III) phosphate. Use the quartz rod to push the crucible far enoughinto the com
17、bustion tube to enable the oxygen inlet to be connected.Page 3DIN 51723 : 2002-06Introduce about 100 ml of water into the absorption flask and keep the pH value of the absorption solutionneutral by adding 2 mol/l sodium hydroxide solution using methyl orange as an indicator.Push the crucible contain
18、ing the sample and the quartz rod forward into the combustion zone using the magnet.Push high-temperature coke samples directly into the combustion zone, but only push coal samples far enoughinto the combustion zone for ignition to take place in the front part of the crucible. When the latter is red
19、 hot(about one minute after ignition), push the sample into the combustion zone to burn it completely.Combustion will take about 45 minutes. When it is complete, drain the absorption liquid out of the headpieceand the flask into a 250 ml volumetric flask. Rinse the headpiece and flask with water, co
20、mbining the rinsingswith the contents of the volumetric flask. Make the contents of the flask up to 250 ml.6 Determination of fluorine content using the oxygen bomb (method B)6.1 PrincipleThe sample is burnt in a digestion bomb and the fluoride liberated is collected in an absorption solution. Theen
21、dpoint is determined by ion chromatography.6.2 ApparatusThe following equipment shall be used.a) Digestion bomb, with a corrosion-resistant interior.b) Station for filling bomb with oxygen, and letting it down.c) Pressure regulator, rated for 40 bar, with safety valve.d) Ignition device.e) Crucible,
22、 of silica glass or stainless steel.f) Clamps, for holding crucible.g) Acetobutyrate capsules.h) 50 ml gas wash bottle, with headpiece containing glass frit.i) Ignition aid (e.g. platinum igniting wire, cotton thread).j) Combustion aid (e.g. benzoic acid pellets, acetobutyrate capsules, paraffin oil
23、, methanol or ethanol).6.3 ReagentsThe following reagents shall be used.a) Oxygen, at least 99,5% (V/V).b) 100 mmol/l sodium hydroxide solution, aqueous, as absorption solution.6.4 ProcedureDepending on fluorine content, weigh 50 mg to 1 000 mg of the sample material to an accuracy of 0,1 mg intoa c
24、rucible. Weigh low-combustibility material into acetobutyrate capsules, adding a combustion aid (e.g.benzoic acid pellets), if necessary.Introduce 10 ml of absorption solution into the digestion bomb and wet the internal surfaces by swirling.Place the crucible into a holder and secure it with clamps
25、.Fit the ignition aid, seal the bomb and introduce oxygen at 30 bar. After ignition, cool the bomb in a water bathat about 20 C for five minutes and then shake it for 30 seconds. Slowly release the combustion gases at theoxygen source and pass them through a wash bottle containing 20 ml of absorptio
26、n solution to retain thecombustion products.Introduce 40 ml of water into the bomb, seal it and shake it for about 30 seconds. Remove an aliquot (VP), makeit up to the required volume (VM) and filter it through a membrane filter of pore size 0,45 m.7 Determination of fluoride content of solutionsDet
27、ermine the fluoride content of the digestion solutions as specified in DIN EN ISO 10304-1.8 Evaluation and expression of resultCalculate the fluoride content of the sample, w(Fan), as a percentage by mass of the fuel used (expressed totwo significant places), from the fluoride content of the digesti
28、on solution, taking account of the initial samplemass, the dilution and the blank value, using equation (1).Page 4DIN 51723 : 2002-06(bP bB) VM VAw(Fan)= (1)VP m 10 000whereVAis the volume of the digestion solution (250 ml for method A and 50 ml for method B);VPis the volume of the aliquot taken fro
29、m the digestion, in ml;VMis the volume of the test solution, in ml;m is the initial sample mass, in g;bPis the fluoride content of the test solution, in mg/l;bBis the fluoride content found in the blank test, in mg/l.9 Precision9.1 Repeatability limit(same operator, same equipment)If two results, ex
30、pressed as percentages by mass, are obtained under repeatability conditions, both results shallbe considered acceptable and in conformity with this standard if they differ by no more than the value givenin table 1.9.2 Reproducibility limit(different operators, different equipment)If two separate lab
31、oratories each obtain a result, expressed as a percentage by mass, under reproducibilityconditions, both results shall be considered acceptable and in conformity with this standard if they differ byno more than the value given in table 1.Table 1: PrecisionFluorine content, Repeatability limit, Repro
32、ducibility limit,w(Fan), r, R,as a percentage as a percentage as a percentage 0,020 0,002 0,004 0,020 to 0,100 10% of mean 20% of mean 0,100 No results are as yet available.NOTE: In comparing results, greater differences may be expected if the samples originate from the samecomposite sample but have
33、 been obtained by division in a state other than analytically fine and the subse-quent sample preparation has been performed separately, or if the samples have been taken from oneparticular consignment at different times.10 Test reportThe test report shall refer to this standard and include the foll
34、owing details as a minimum:a) description of the sample;b) expression of result, as specified in clause 8;c) any unusual observations made during the test.11 Quality control11.1 Blank testA reagent blank value shall be determined in every series of tests using a pure substance (e.g. benzoic acid)ins
35、tead of the sample and the result shall be recorded (e.g. on a control card) and evaluated.11.2 Accuracy of recoveryA standard fuel sample (e.g. BCR 040, F (111,4 t 8,5) mg/kg) shall preferably be used to check the accuracyof recovery over the entire method. As an alternative, organic pure substances1) may be used.Othe relevant standardDIN 51700 General information and survey of methods of testing solid fuels1) Refer for details to the Normenausschuss Bergbau, Am Technologiepark 1, 45307 Essen, Germany.
