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1、International Standard INTERNATIONAL ORGANIZATION FOR STANDARDIZATIONW.4EWlYHAPOIlHAR OPrAHW3AUHR IlO CTAHPTH3AUMH.OAGANlSATlON INTERNATIONALE DE NORMALISATION Carbonaceous materials for the production of aluminium - Pitch for electrodes - Determination of density - Pyknometric method Prod Descripto
2、rs : aluminium, production, pitch (materials), electrodes, tests, determination, density (mass/volume), pyknometric analysis, test 8 equipment. 8 s: Price based on 3 pages Foreword IS0 (the International Organization for Standardization) is a worldwide federation of national standards bodies (IS0 me
3、mber bodies). The work of developing International Standards is carried out through IS0 technical committees. Every member body interested in a subject for which a technical committee has been authorized has the right to be represented on that committee. International organizations, governmental and
4、 non-governmental, in liaison with ISO, also take part in the work. Draft International Standards adopted by the technical committees are circulated to the member bodies for approval before their acceptance as International Standards by the IS0 Council. International Standard IS0 6999 was developed
5、by Technical Committee ISO/TC 47, Chemistry, and was circulated to the member bodies in July 1992. It has been approved by the member bodies of the following countries: Australia Hungary Austria India Belgium Italy Canada Korea, Rep. of China Netherlands Czechoslovakia New Zealand Egypt, Arab Rep. o
6、f Nigeria France Portugal Germany, F.R. Romania South Africa, Rep. of Spain Sweden Switzerland Thailand USA USSR The member body of the following country expressed disapproval of the document on technical grounds : United Kingdom 0 international Organization for Standardization, 1983 0 Printed in Sw
7、itzerland -,-,- INTERNATIONAL STANDARD IS0 6999-1983 (E) Carbonaceous materials for the production of aluminium - Pitch for electrodes - Determination of density - Pyknometric method 0 Introduction The density of pitch used for preparation of electrodes for the production of aluminium is a property
8、which gives a guide to its consistency of quality. Knowledge of this parameter is essential for optimum use of pitch. 1 Scope and field of application This International Standard specifies a pyknometric method for determination of density of pitch used for preparation of elec- trodes for use in the
9、aluminium industry. 2 References IS0 3507, Pyknometers. IS0 5725, Precision of test methods - Determination of repeatability and reproducibility by inter-laboratory tests. IS0 6257, Carbonaceous materials used in the production of aluminium - Pitch for electrodes - Sampling. 3 Principle Measurement,
10、 by a pyknometric method, of the density of pitch at 25 OC, after degassing under vacuum. 4 Reagents and materials During the determination, use only reagents of recognized analytical grade and distilled water or water of equivalent purity. 4.1 Ethanol, 95 % (V/V). 4.2 Acetone. 4.3 Non-ionic wetting
11、 agent, 0,l % (m/m) aqueous solution. 5 Apparatus Ordinary laboratory material and 5.1 Pyknometer, Gay-Lussac, type 3, capacity 25 ml (see IS0 3507). 5.2 Vacuum pump, fitted with safety valve and filter, capacity about 1 ma/h, capable of producing a residual pressure of 33 mbar. 5.3 Airtight contain
12、er, to hold the pyknometer (5.1) capable of being maintained under vacuum during the deter- mination and fitted with a suitable separating funnel. WARNING - When under vacuum, place behind a suitable safety screen. A typical assembled apparatus is shown in the figure. 5.4 Electric oven, capable of b
13、eing controlled at 120 z!z 2 T. 5.5 Water bath, capable of being controlled at 25 + 0.05 OC. . 6 Sampling Sampling shall be carried out according to the method specified in IS0 6257. 1 -,-,- IS0 6999-1983 (E) Figure - Typical apparatus for pyknometric deter *mination of density 7 Procedure 7.1 Calib
14、ration of the pyknometer Commercial pyknometers are usually calibrated at 20 OC whereas the present determination is carried out at 25 T. It is therefore necessary to calibrate the pyknometer at this latter temperature. 7.1.1 Determination of the mass of the pyknometer WARNING - Sulfo-chromic mixtur
15、e causes severe burns, is carcinogenic and in contact with combustible material, may cause fire. Avoid contact with eyes, skin and clothing. Do not breathe vapour. Wear protective clothing and goggles when using this material. 2 Wash the pyknometer (5.1) with a warm sulpho-chromic mix- ture, taking
16、all necessary precautions. Wash carefully first with tap water then with distilled water, then with the ethanol (4.1) and finally with the acetone (4.2). Dry the pyknometer in an air stream and weigh to the nearest 0,000 1 g (me). 7.1.2 Determination of the volume of the pyknometer Fill the pyknomet
17、er with distilled water at a temperature of 23 to 24 T, insert its stopper, making sure that water escapes through the orifice in the stopper, and wipe the pyknometer with filter paper. Place the filled pyknometer in the water bath (5.51, controlled at 25 + 0,05 T, and allow it to reach thermal equi
18、librium at this temperature. Level off the water to the top of the stopper. -,-,- IS0 6999-1983 (El Remove the pyknometer from the water bath, cool slightly with the acetone (4.2) and wipe carefully with filter paper. Weigh the filled pyknometer to the nearest 0,000 1 g (ml). The volume V, in millil
19、itres, of the pyknometer is given by the formula ml - mo 0,997 05 pyknometer and continue the determination according to the conditions specified in 7.1.2, starting from the paragraph: “Place the filled pyknometer in the water bath .” Weigh the filled pyknometer to the nearest 0,000 1 g (ms). 8 Expr
20、ession of results 8.1 Calculations where m. is the mass, in grams, of the dry, empty pyknometer; ml is the mass, in grams, of the pyknometer filled with water: 0,997 05 is the density of water, in grams per millilitre, at 25 “C. NOTES 1 The volume V of the pyknometer is rounded off to 0,000 1 ml. Th
21、e calibration should be repeated every 3 months; the mass “0 should re- main constant to 0,001 g. 2 It is essential that the volume of the pyknometer be determined several times on different days, to eliminate the effect of outside in- fluences as well as the small differences in regulation of the w
22、ater bath. The volume V should represent the mean of 8 to 10 determinations. 7.2 Determination of density 7.2.1 Test portion Weigh to the nearest 0,000 1 g, 5 Z!Z 0,l g of the laboratory sample (clause 6) with a particle size between 1 and 2 mm (m2) into the dry, empty pyknometer, prepared according
23、 to 7.1.1. 7.2.2 Determination Fill the separating funnel fitted to the airtight container (5.3), with the wetting solution (4.3). Place the unstoppered pyknometer containing the test portion (7.2.1) in the container and, with the stopcock of the separating funnel closed, run the vacuum pump (5.2) f
24、or about 5 min until a residual pressure of 33 to 35 mbar is obtained. Slowly open the stopcock of the separating funnel and allow the wetting agent solution to fall, drop by drop, until about 20 ml have been added to the pyknometer. Close the stopcock. Maintain the vacuum until any air bubbles in t
25、he pyknometer have disappeared. Restore the pressure within the container to ambient level, open the container, remove the pyknometer and fill it completely with the wetting agent solution. Close the The density of the pitch, expressed in grams per millilitre, is given by the formula m3 V- m3 - (m2
26、+ mo) 0,997 05 where m. is the mass, in grams, of the dry, empty pyknometer; m2 is the mass, in grams, of the test portion (7.2.1); m3 is the mass, in grams, of the pyknometer containing the test portion and water; 0,997 05 is the density of the wetting agent solution (4.31, pratically equal to that
27、 of the water. 8.2 Precision (see IS0 5725, sub-clause 3.1) Standard deviation of repeatability: 0,004 g/ml. Standard deviation of reproducibility: 0,006 g/ml. Results rounded off to the third place of decimals. 8.3 Checking the determination Systematic errors can be checked by carrying out determin
28、a- tions on reference materials from time to time. 9 Test report The test report shall include the following particulars: a) an identification of the sample; b) the reference of the method used; c) the results and the method of expression used; d) any unusual features noted during the determination; e) any operations not included in this International Stan- dard or in the International Standards to which reference is made, or regarded as optional. 3