BS 6043-3 2-1997 Methods of sampling and test for carbonaceous materials used in aluminium manufacture - Electrodes - Determination of density of cathode blocks and prebaked anodes.pdf

1、BRITISH STANDARD BS 6043-3.2: 1997 ISO 9088:1997 Methods of Sampling and test for carbonaceous materials used in aluminium manufacture Part 3: Electrodes Section 3.2: Determination of density ofcathode blocks and prebaked anodes ICS 71.100.10BS6043-3.2:1997 This British Standard, having been prepare

2、d under the directionof the Sector Board forMaterials and Chemicals, waspublished under the authorityof the Standards Boardand comes into effect on 15June 1997 BSI 04-2000 ISBN 0 580 27538 8 Amendments issued since publication Amd. No. Date CommentsBS6043-3.2:1997 BSI 04-2000 i Contents Page Nationa

3、l foreword ii Foreword iii Text of ISO 9088 1BS6043-3.2:1997 ii BSI 04-2000 National foreword This British Standard reproduces verbatim ISO9088:1997 and implements it as the UK national standard. The UK participation in its preparation was entrusted to Technical Committee CII/24, Raw materials for t

4、he aluminium industry, which has the responsibility to: 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 informed; monitor related international and European devel

5、opments and promulgate them in the UK. A list of organizations represented on this committee can be obtained on request to its secretary. Part 3 of BS6043provides methods of test for prebaked anodes and cathode blocks as follows: Note In regard to clause4.4, it is common practice in the United Kingd

6、om to use paraffin (kerosene) in place of xylene. This alternative may be used, provided that both the use of paraffin and the relative density of the paraffin are recorded in the test report,9 e). Cross-references The British Standards which implement international or European publications referred

7、 to in this document may be found in the BSI Standards Catalogue under the section entitled “International Standards Correspondence Index”, or using the “Find” facility of the BSI Standards Electronic Catalogue. A British Standard does not purport to include all the necessary provisions of a contrac

8、t. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Section Subject Identical with 3.1 Sampling 3.1.1 Sampling of cathode blocks ISO 8007-1 a 3.1.2 Sampling of prebaked anodes ISO 8

9、007-2 a 3.2 Determination of density of cathode blocks and prebaked anodes ISO 9088 3.3 Determination of the open porosity and bulk density of prebakedanodes and cathode blocks 3.3.1 Dimensions method ISO 12985-1 a 3.3.2 Hydrostatic method ISO 12985-2 a 3.4 Determination of electrical resistivity IS

10、O 11713 a 3.5 Determination of flexural strength ISO 12986 a 3.6 Determination of thermal conductivity ISO 12987 a 3.7 Determination of chemical reactivity ISO 12988 a 3.8 Determination of compressive strength ISO 12989 a 3.9 Determination of thermal expansion ISO 14420 a 3.10 Determination of sodiu

11、m expansion ISO 15379 a 3.11 Determination of air permeability a a In preparation Summary of pages This document comprises a front cover, an inside front cover, pagesi andii, theISO title page, pagesii toiv, pages1 to4andabackcover. This standard has been updated (see copyright date) and may have ha

12、d amendments incorporated. This will be indicated in the amendment table on the inside front cover.BS6043-3.2:1997 ii BSI 04-2000 Contents Page Foreword iii 1 Scope 1 2 Normative references 1 3 Principle 1 4 Reagents and materials 1 5 Apparatus 1 6 Sampling 1 7 Procedure 3 8 Expression of results 4

13、9 Test report 4 Figure 1 Typical degassing apparatus 2 Descriptors: Extractive metallurgy, aluminium, carbon electrodes, carbonaceous materials, tests, determination, density (mass/volume), xylenes, pycnometric analysis.BS6043-3.2:1997 BSI 04-2000 iii Foreword ISO (the International Organization for

14、 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 has been established has the

15、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 theInternational Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. Draft Inter

16、national Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least75% of the member bodies casting a vote. International Standard ISO9088was prepared by Technical Committee ISO/TC47, Chemistry,

17、 Subcommittee SC7, Aluminium oxide, cryolite, aluminium fluoride, sodium fluoride, carbonaceous products for the aluminiumindustry.iv blankBS6043-3.2:1997 BSI 04-2000 1 1 Scope This International Standard specifies a pyknometric method for the determination of the true density in xylene of cathode b

18、locks and prebacked anodes used for the production of aluminium. 2 Normative references The following standards contain provisions which, through reference in this text, constitute provisions of this International Standard. At the time of publication, the editions indicated were valid. All standards

19、 are subject to revision, and parties to agreements based on this International Standard are encouraged to investigate the possibility of applying the most recent editions of the standards indicated below. Members of IEC and ISO maintain registers of currently valid International Standards. ISO 3507

20、:1976, Pyknometers. ISO 8007:1985, Carbonaceous materials used in the production of aluminium Sampling from cathodic blocks and prebaked anodes General. 3 Principle The true density of cathode blocks and prebaked anodes is measured in xylene in a pyknometer after degassing under a vacuum. 4 Reagents

21、 and materials During the determination, unless otherwise stated, use only reagents of recognized analytical grade and only distilled water, or water of equivalent purity, degassed by boiling for1h. 4.1 Ethanol, 95% (V/V). 4.2 Acetone 4.3 Sulfuric acid, density approx.1,84g/ml, about98% (m/m) soluti

22、on. 4.4 Xylene, commercial grade, density about0,86g/ml. WARNING Xylene burns the skin and can also be absorbed into the system through the skin. In addition, inhalation of the vapour from hot material is to be avoided. 5 Apparatus 5.1 Pyknometer, type3as defined in ISO3507 (Gay-Lussac), capacity25m

23、l. 5.2 Degassing apparatus (seeFigure 1), comprising the following items: 5.2.1 Container (1) for the pyknometer, consisting ofa glass beaker (2) with removable lid (3) and O-ring (4), capable of containing the pyknometer without its stopper. The container outlet (5) is connected to a pump (not show

24、n). 5.2.2 Filling device (6), fitted to the container by a ground-glass joint (7). A tube (8) extends down into the pyknometer. A reservoir (9) with a ground-glass stopper (10) contains the pyknometer liquid which is allowed to flow into the pyknometer through a teflon valve(11). 5.2.3 Stand (12), t

25、o support the beaker when no vacuum is applied to the degassing apparatus. Arod(13) with a spring (14) allows the beaker (2), with the pyknometer in it, to be shaken to facilitate the evolution of a gas bubbles during degassing. The apparatus is made of glass. A rotary pump is connected to the outle

26、t of the apparatus via an oil trap (15). A manometer (16) is connected to the vacuum system between the pump and the oil trap. The vacuum is adjusted so that the manometer, which is about600mm from the joint (7) between the container and the filling device, registers1,3kPa 0,3kPa. A valve (17) is fi

27、tted to allow air back into the apparatus. This has to be done slowly and with due care. NOTEAt a pressure of 1,3 kPa 0,3kPa and an ambient temperature of25 C, slight vapourization of xylene may occur until equilibrium is reached, but this is of no consequence. The apparatus described above is only

28、an example; other apparatus with the same characteristics maybe used. 5.3 Drying oven, capable of being maintained at120 C 2 C. 5.4 Thermostatically controlled bath, capable of being maintained at25 C 0,05 C. 5.5 Grinder, capable of grinding the sample to a particle size of less than634m. The parts

29、which come into contact with the sample shall be made of hardmetal to avoid contamination. 5.6 Filter paper 5.7 Jaw-type crusher 6 Sampling Sample in accordance with ISO8007.BS6043-3.2:1997 2 BSI 04-2000 Figure 1 Typical degassing apparatusBS6043-3.2:1997 BSI 04-2000 3 7 Procedure 7.1 General Carry

30、out all weighings to an accuracy of0,1mg. When the pyknometer contains a liquid, stabilize itstemperature in the thermostatically controlled bath(5.4) at25 C 0,05 C before weighing. 7.2 Preparation of the sample Drill a cylinder or cut a piece out of the carbon block and crush it into small pieces u

31、sing the jaw-type crusher(5.7). Grind the sample to a particle size of634m usingthe grinder (5.5). Store the ground material inan airtight container until required for the determination. Before the determination, dry the sample in the drying oven(5.3) at 120 C 2 C for8h. Then cool in a desiccator co

32、ntaining silicagel. NOTEIn 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 type (carbon blocks, cathode blocks, prebaked anodes), using the grinder av

33、ailable. This can be done with any apparatus capable of determining the size of such particles. 7.3 Calibration of the pyknometer Commercial pyknometers are usually calibrated at20 C, whereas the present determination is carried out at25 C. It is therefore necessary to calibrate the pyknometer at th

34、is temperature. 7.3.1 Determination of pyknometer mass Wash the pyknometer(5.1) with warm concentrated sulfuric acid solution(4.3), taking all necessary precautions. Rinse carefully, first with running tapwater, then with distilled water, then with ethanol(4.1), and finally with acetone(4.2). Weight

35、he perfectly dry pyknometer to the nearest0,1mg (mass m 0 ). 7.3.2 Determination of pyknometer volume Fill the pyknometer with distilled water degassed at23 C to24 C, with the ground-glass stopper firmly inserted and the pyknometer cleaned of excess water with filter paper(5.6). Place the filled pyk

36、nometer in the thermostatically controlled bath and heat to25 C 0,05 C. During heating, remove the liquid which emerges from the capillary carefully with filter paper. When no more water runs out, the pyknometer has reached the temperature of the bath. Remove it from the bath and dry it carefully. T

37、o avoid the pyknometer overflowing due to the absorption of heat from thehand, it may be briefly chilled in cooler water orwith acetone(4.2) before drying it. Weigh the pyknometer, which shall be completely dry on theoutside, to the nearest0,1mg (mass m 1 ). The volume V, in millilitres, of the pykn

38、ometer is given by the equation where Determine the pyknometer volume several times ondifferent days to eliminate the effect of external influences, as well as any small differences in the temperature of the bath. The result shall be taken as the mean of8to10determinations. Individual values shall n

39、ot deviate from the mean value by more than 0,0015ml. Round the result to the nearest0,001ml. 7.3.3 Frequency of calibration Repeat the calibration at least every3months. Themass m 0shall remain constant to 1mg. NOTESince no two pyknometers have exactly the same volume, each pyknometer has to be cal

40、ibrated individually. It is not necessary to check the volume every time the pyknometer is used for a series of density determinations, for instance, although it is usual to check the mass each time. 7.4 Determination of the density of the xylene(4.4) Follow the procedure described in7.3.2. The dens

41、ity of the xylene, x , expressed in grams per millilitre, is given by the equation where The result shall be taken as the mean of10determinations made over a number of days to eliminate the effect of external influences. 7.5 Determination of the density of the sample 7.5.1 Test portion Weigh, to the

42、 nearest0,1mg,5g 0,1g of the sample (see7.2) (mass m 3 ) into the clean, dry, empty pyknometer, prepared in accordance with7.3.1. 7.5.2 Determination The determination shall not be carried out if the ambient temperature exceeds30 C. m 0 is the mass, in grams, of the clean, dry, empty pyknometer; m 1

43、 is the mass, in grams, of the pyknometer filled with distilled and degassed water; 0,99705 is the density of water, in grams per millilitre, at25 C. m 0and V are as defined in7.3.2; m 2 is the mass, in grams, of the pyknometer filled with xylene (4.4).BS6043-3.2:1997 4 BSI 04-2000 Place the pyknome

44、ter, containing the test portion but without its stopper, in the container of the degassing apparatus(5.2). Before adding xylene, evacuate for15min to a residual pressure of1,3kPa 0,3kPa with the xylene feed closed. This pressure is necessary for a repeatability of 0,004g/ml (see8.2). If a precision

45、 of only 0,01g/ml is required, a pressure of2,6kPa 0,3kPa is sufficient. Add xylene drop by drop to the pykometer. When thetest portion is covered with20mm of xylene at the most, interrupt the addition of xylene. Continue the evacuation of air, occasionally shaking the pyknometer and the support, un

46、til the evolution of air bubbles has stopped. In general, this takes up to60min. Slowly allow air to enter the degassing apparatus. Remove the pyknometer and fill with xylene to thelower edge of the ground. Allow the test portion to settle for at least30min, completely fill the pyknometer with xylen

47、e and insert the stopper. Remove from the outside of thepyknometer any xylene which overflows. Repeat the procedure given in the second paragraph of7.3.2 (“Place the filled pyknometer.”). Weigh the pyknometer containing the test portion and xylene to the nearest0,1mg (mass m 4 ). 7.6 Checking the de

48、termination The apparatus can be checked for systematic errorsby carrying out determinations on standard samples from time to time. 8 Expression of results 8.1 Method of calculation The density of the sample, expressed in grams per millilitre, is given by the equation where Round the result to the t

49、hird decimal place. 8.2 Precision 8.2.1 General The precision data for this method were obtained inaccordance with ISO5725:1986, Precision of testmethods Determination of repeatability andreproducibility for a standard test method by inter-laboratory tests (now withdrawn). 8.2.2 Repeatability, r The results of two determinations carried out on thesame sample under repeatability conditions (same operator, same apparatus, short time interval between the determinations) may be considered to be acceptable if they do