1、 g49g50g3g38g50g51g60g44g49g42g3g58g44g55g43g50g56g55g3g37g54g44g3g51g40g53g48g44g54g54g44g50g49g3g40g59g38g40g51g55g3g36g54g3g51g40g53g48g44g55g55g40g39g3g37g60g3g38g50g51g60g53g44g42g43g55g3g47g36g58aluminium Determination of density by gas pyknometry (volumetric) using helium as the analysis gas
2、Solid materialsICS 71.100.10Carbonaceous materials used in the production of BRITISH STANDARDBS ISO 21687:2007BS ISO 21687:2007This British Standard was published under the authority of the Standards Policy and Strategy Committee on 31 May 2007 BSI 2007ISBN 978 0 580 50730 4Amendments issued since p
3、ublicationAmd. No. Date Commentscontract. Users are responsible for its correct application.Compliance with a British Standard cannot confer immunity from legal obligations. National forewordThis British Standard was published by BSI. It is the UK implementation of ISO 21687:2007.The UK participatio
4、n in its preparation was entrusted to Technical Committee CII/24, Raw materials for the aluminium industry.A list of organizations represented on this committee can be obtained on request to its secretary.This publication does not purport to include all the necessary provisions of a Reference number
5、ISO 21687:2007(E)INTERNATIONAL STANDARD ISO21687First edition2007-03-01Carbonaceous materials used in the production of aluminium Determination of density by gas pyknometry (volumetric) using helium as the analysis gas Solid materials Produits carbons utiliss pour la production de laluminium Dtermin
6、ation de la masse volumique vraie par la mthode pycnomtrique gazeuse (volumtrique) utilisant de lhlium comme gaz analytique Matriaux solides BS ISO 21687:2007ii iiiContents Page Foreword iv Introduction v 1 Scope . 1 2 Normative references . 1 3 Terms and definitions. 1 4 Principle. 2 5 Apparatus an
7、d materials 2 6 Sampling, sample preparation and drying.2 7 Procedure 3 8 Calculation. 3 9 Precision 4 10 Test report . 5 Bibliography . 6 BS ISO 21687:2007iv Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies).
8、 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 has been established has the right to be represented on that committee. International organizations, governmental and non-
9、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 standardization. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part
10、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 bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a
11、 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 or all such patent rights. ISO 21687 was prepared by Technical Committee ISO/TC 226, Materials for the production of prim
12、ary aluminium. BS ISO 21687:2007vIntroduction This International Standard is based on a DIN method: DIN 51913:2001, Testing of carbon materials Determination of density by gas pycnometer (volumetric) using helium as the measuring gas Solid materials prepared by Arbeitsausschu NMP 281, Test Methods f
13、or Carbon and Graphite. The density of calcined petrol coke permits an estimate of the degree of calcination of the analysed material. BS ISO 21687:2007blank1Carbonaceous materials used in the production of aluminium Determination of density by gas pyknometry (volumetric) using helium as the analysi
14、s gas Solid materials 1 Scope This International Standard specifies a method for the determination of the density of green and calcined petroleum coke and similar solid materials (e.g. electrodes). This standard is also suitable for hydrocarbons with a high-temperature boiling range and for other so
15、lid materials. This method is not suitable for graphitized material. 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 do
16、cument (including any amendments) applies. ISO 3310-1:2000, Test sieves Technical requirements and testing Part 1: Test sieves of metal wire cloth ISO 6257:2002, Carbonaceous materials used in the production of aluminium Pitch for electrodes Sampling ISO 6375:1980, Carbonaceous materials for the pro
17、duction of aluminium Coke for electrodes Sampling ISO 8007-1:1999, Carbonaceous materials used in the production of aluminium Sampling plans and sampling from individual units Part 1: Cathode blocks 3 Terms and definitions For the purposes of this document, the following terms and definitions apply.
18、 3.1 density of a solid material mass m per unit volume V mV = (1) where is the density, expressed in grams per cubic centimetre; m is the mass, in grams; V is the volume of the solid, in cubic centimetres, excluding any pore volume. BS ISO 21687:20072 NOTE Accessible and inaccessible pores contribu
19、te to the total pore volume of the solid. However, only accessible pores can be excluded from the volume of the solid. 4 Principle A sample is ground and sieved to a size u 0,063 mm. The density is determined volumetrically in a gas pyknometer with helium as the analysis gas. The mass of the dry tes
20、t portion is determined and the test portion is loaded into the analysis chamber. Helium gas is introduced into the analysis chamber and pressurized to a set value. The helium gas is subsequently expanded into an expansion chamber. The instrument records the equilibration pressures for both steps. T
21、he density of the sample is calculated from the mass m of the dry sample and its volume V determined by gas pyknometry. 5 Apparatus and materials 5.1 Crusher, e.g. jaw-type, faced with a hard material that will not be abraded to minimize sample contamination. 5.2 Grinder, capable of grinding the sam
22、ple to a particle size of less than 0,063 mm, and with the parts that come into contact with the sample made of a hard material that will not be abraded to minimize sample contamination. 5.3 Porcelain bowl, 50 mm to 60 mm in diameter and 30 mm to 40 mm in depth. 5.4 Copper plate. 5.5 Sieve, with a m
23、esh width of 0,063 mm in accordance with ISO 3310-1. 5.6 Drying oven, (preferably with vacuum option) capable of operating at temperatures W 110 C. NOTE Use of a drying oven without a vacuum option may reduce the precision given in Clause 9. 5.7 Dessicator, containing silica gel. 5.8 Gas pyknometer.
24、 5.9 Calibration balls, with known volume. 5.10 Sample cup, tared. 5.11 Helium, with a minimum purity of 99,996 % (by volume fraction). 5.12 Analytical balance, accurate to 0,1 mg. 6 Sampling, sample preparation and drying 6.1 Sampling and sample preparation 6.1.1 Pitch Take a sample of the material
25、 in accordance with ISO 6257. Coarsely crush the pitch sample, place about 50 g in the porcelain bowl (5.3), weigh and dry for about 2 h in the oven (5.6) at a temperature of about 50 C above the softening point and at least 110 C. During the process, stir the sample to avoid air bubbles. Repeat wei
26、ghing and drying until the mass remains constant. BS ISO 21687:20073Pour the sample onto the copper plate (5.4), allow to cool then grind the sample to a particle size of u 0,063 mm using the grinder (5.2) and then sieve through the sieve (5.5). Take a test portion of the sieved sample material u 0,
27、063 mm by filling the tared sample cup. 6.1.2 Coke Take a sample of the material in accordance with ISO 6375. Crush, grind and sieve the sample to a particle size of u 0,063 mm using the grinder (5.2), and then sieve through the sieve (5.5). Store this sample in an airtight container until required
28、for the determination. NOTE In order to avoid the need to verify the particle size of each sample, it is advisable to determine the grinding conditions which will enable the required particle size to be obtained with each sample using the grinder available. This can be done with any apparatus capabl
29、e of determining the size of such particles. 6.1.3 Cathode blocks and prebaked anodes Take a sample of the material in accordance with ISO 8007-1. Drill a cylinder or cut a piece out of the carbon block. Crush, grind and sieve the sample to a particle size of u 0,063 mm using the grinder (5.2), and
30、then sieve through the sieve (5.5). Store this sample in an airtight container until required for the determination. NOTE In order to avoid the need to verify the particle size of each sample, it is advisable to determine the grinding conditions which will enable the required particle size to be obt
31、ained with each sample type (cathode blocks, prebaked anodes), using the grinder available. This can be done with any apparatus capable of determining the size of such particles. 6.2 Drying of coke, cathode blocks and prebaked anodes Take a test portion of the sieved sample material u 0,063 mm by fi
32、lling the tared sample cup. Place the test portion and sample cup in the drying oven at a temperature of 110 C and a pressure of 1 kPa (10 mbar) for at least 30 min. Remove from the oven, allow to cool in the desiccator (5.7), weigh, reheat again to 110 C, and introduce the sample cup immediately in
33、to the gas pyknometer. 7 Procedure Calibrate the apparatus and perform the analysis according to the operators manual supplied by the equipment manufacturer. 8 Calculation Calculate the density , in grams per cubic centimetre (g/cm3), using the equation mV = (2) where is the density of the sample, e
34、xpressed in grams per cubic centimetre (g/cm3); m is the mass of the sample, in grams (g); V is the measured volume of the sample, in cubic centimetres (cm3). BS ISO 21687:20074 The volume of the sample is usually calculated by the analysis instrument, but may also be calculated from the analysis da
35、ta using the equation expcell121VVVPP=(3) where Vcellis the calibrated volume of the empty analysis chamber, in cubic centimetres (cm3); Vexpis the calibrated volume of the expansion chamber, in cubic centimetres (cm3); P1is the filling pressure of the analysis chamber before the expansion, in kPa;
36、P2is the pressure after the expansion, in kPa. 9 Precision 9.1 Determination The precision of the method was determined in three Round Robins: a) green and calcined coke; b) pitch; c) baked anodes, cathode blocks and sidewall blocks; and calculated by ASTM E 691:1999 under the following analysis con
37、ditions: Gas pressure of helium approximately 150 kPa Purges 20 Purge/filling pressure 135 kPa Equilibration rate 0,034 5 kPa/min The precision is given for a 95 % confidence level. 9.2 Repeatability The difference between two results, collected on the same sample by the same person with the same in
38、strument under constant analysis conditions, should only in one out of 20 cases be larger than the mentioned value, if the method described is used under common and correct conditions. Pitch: in the range 1,28 to 1,32 g/cm3, the following precision has been obtained: Repeatability (r): 0,003 g/cm3Co
39、ke: in the range 2,06 to 2,09 g/cm3, the following precision has been obtained: Repeatability (r): 0,004 g/cm3Anodes: in the range 2,06 to 2,12 g/cm3, the following precision has been obtained: Repeatability (r): 0,002 g/cm3BS ISO 21687:200759.3 Reproducibility The difference between two single and
40、independent results, collected on identical samples by different persons in different laboratories, should only in one out of 20 cases be larger than the mentioned value, if the method described is used under common and correct conditions. Pitch: in the range 1,28 to 1,32 g/cm3, the following precis
41、ion has been obtained: Reproducibility (R): 0,015 g/cm3Coke: in the range 2,06 to 2,09 g/cm3, the following precision has been obtained: Reproducibility (R): 0,014 g/cm3Anodes: in the range 2,06 to 2,12 g/cm3, the following precision has been obtained: Reproducibility (R): 0,006 g/cm39.4 Examples of
42、 use 9.4.1 Repeatability Given a pitch with real density in the range 1,28 to 1,32 g/cm3, if two test portions are measured by the same operator in the same laboratory, the measurements are acceptable if they differ by less than 0,003 g/cm3. 9.4.2 Reproducibility Given a coke with real density in th
43、e range 2,06 to 2,09 g/cm3, if two test portions are measured at different laboratories, the measurements are acceptable is they differ by less than 0,014 g/cm3. 10 Test report The test report shall include the following information: a) a reference to this International Standard; b) details necessar
44、y for the complete identification of the material tested; c) the type of pyknometer and its manufacturer; d) the density of the sample, in grams per cubic centimetre (g/cm3), rounded to 0,001 g/cm2; e) any agreed deviations from this International Standard; f) the date of the test. BS ISO 21687:2007
45、6 Bibliography 1 ASTM E 691:1999, Standard practice for conducting an interlaboratory study to determine the precision of a test method BS ISO 21687:2007blankBS ISO BSI389 Chiswick High RoadLondonW4 4AL21687:2007BSI British Standards InstitutionBSI is the independent national body responsible for pr
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