1、BRITISH STANDARD BS ISO 5940-2:2007 Carbonaceous materials used in the production of aluminium Pitch for electrodes Part 2: Determination of the softening point (Mettler softening point method) ICS 71.100.10 BS ISO 5940-2:2007 This British Standard was published under the authority of the Standards
2、Policy and Strategy Committee on 29 June 2007 BSI 2007 ISBN 978 0 580 52906 1 National foreword This British Standard was published by BSI. It is the UK implementation of ISO 5940-2:2007. The UK participation in its preparation was entrusted to Technical Committee CII/24, Raw materials for the alumi
3、nium 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 contract. Users are responsible for its correct application. Compliance with a British Standard cannot conf
4、er immunity from legal obligations. Amendments issued since publication Amd. No. Date Comments Reference number ISO 5940-2:2007(E)INTERNATIONAL STANDARD ISO 5940-2 First edition 2007-05-01 Carbonaceous materials used in the production of aluminium Pitch for electrodes Part 2: Determination of the so
5、ftening point (Mettler softening point method) Produits carbons utiliss pour la production de laluminium Brai pour lectrodes Partie 2: Dtermination du point de ramollissement (Point de ramollissement par la mthode Mettler) BS ISO 5940-2:2007ii iii Foreword ISO (the International Organization for Sta
6、ndardization) 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 righ
7、t 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 the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. International
8、Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 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
9、 International Standard requires approval by at least 75 % of the member bodies casting a 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 5
10、940-2 was prepared by Technical Committee ISO/TC 226, Materials for the production of primary aluminium. ISO 5940 consists of the following parts, under the general title Carbonaceous materials used in the production of aluminium Pitch for electrodes: Part 1: Determination of the softening point by
11、the ring-and-ball method (will replace ISO 5940:1981) Part 2: Determination of the softening point (Mettler softening point method) BS ISO 5940-2:2007iv Introduction This part of ISO 5940 is based on DIN 51920 Testing of carbonaceous materials Determination of the Mettler softening point Binding and
12、 impregnating materials, prepared by NMP 281 “Prfverfahren fr Kohlenstoff und Graphit“ and published by DIN, Deutsches Institut fr Normung e.V., Berlin. Coal-tar pitch is used as a binding and impregnating agent in the production of carbon anodes for primary aluminium metal production. When heated,
13、pitch transforms gradually from a solid to a liquid. The analytical determination of a softening point described in this method is useful for characterizing this thermal behaviour of the coal-tar pitch when used as binder. The softening point is expressed as a temperature, in degrees Celsius (C). An
14、nex A gives an approximate comparison with softening points determined by other methods. BS ISO 5940-2:2007 1 Carbonaceous materials used in the production of aluminium Pitch for electrodes Part 2: Determination of the softening point (Mettler softening point method) 1 Scope This part of ISO 5940 sp
15、ecifies a method to determine the softening point of pitches by the Mettler method, within the range of 50 C to 180 C. It can be used for other organic materials that are used as binder and impregnating agents, where they have a Mettler softening point within the range of 50 C to 150 C. 2 Normative
16、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) applies. ISO 6257, Carbonaceous materials used
17、in the production of aluminium Pitch for electrodes Sampling DIN 1333, Presentation of numerical data DIN 51848-1, Testing of mineral oils Precision General introduction, definitions and application to specifications 3 Principle A test portion of pitch is placed within a cylindrical sample cup with
18、an outlet diameter of 6,35 mm. The temperature is increased under constant conditions in air, until softened material issues from the outlet and interrupts a light barrier 19 mm below. BS ISO 5940-2:20072 4 Apparatus and reagents 4.1 Test apparatus 1)(see Figure 1) consisting of the parts given in 4
19、.1.1 to 4.1.7. 4.1.1 Electrically heated furnace. 4.1.2 Sample cup (see Figure 2), made from chrome-plated yellow brass or chrome nickel-steel. 4.1.3 Resistance thermometer, capable of measuring temperatures from 50 C to 180 C. 4.1.4 Cup holder. 4.1.5 Light barrier, capable of sensing the material a
20、s it issues from the sample cup. 4.1.6 Control unit, with a temperature indicator for the thermometer (4.1.3), and an indicator to show the operational status of the machine. 4.1.7 Collector, for the softened material. 4.2 Bowl, made of porcelain, Teflon or metal with a volume of about 50 ml. 4.3 Pl
21、ate, with a smooth surface, e.g. made of metal or glass. 4.4 Knife or spatula. 4.5 Release agent for cup, e.g. a mixture of glycerine and dextrin, ratio 1:1. 4.6 Electro-hydraulic press, as described in ASTM D3104, or another suitable press for filling the sample cup with grindable binder. 4.7 Punch
22、, suitable for pressing grindable pitch. 4.8 Balance, capable of weighing grindable pitch to an accuracy of 0,1 g. 1) Available from Mettler Toledo Inc. http:/. Further information on sources of supply can be obtained from: DIN-Bezugsquellen fr normgerechte Erzeugnisse of DIN Deutsches Institut fr N
23、ormung e. V., Burggrafenstrae 6, D-1000 Berlin 30. This information is given for the convenience of users of this part of ISO 5940 and does not constitute an endorsement by ISO of this apparatus. BS ISO 5940-2:2007 3Key 1 electrically heated furnace 2 sample cup 3 resistance thermometer 4 cup holder
24、 5 light barrier 6 control unit with temperature indicator Figure 1 Schematic picture of the testing apparatus BS ISO 5940-2:20074 Dimensions in millimetres Figure 2 Sample cup 5 Sampling Take a sample of the material in accordance with ISO 6257. 6 Sample preparation 6.1 Types of material Pitch can
25、be grindable or non-grindable. Prepare non-grindable pitch by melting (see 6.2) and grindable pitch by melting or pressing (see 6.3). 6.2 Preparation of pitch by melting Melt a test sample of about 20 g of the air-dry sample into the bowl (4.2), taking care to ensure that no overheating occurs at th
26、e wall of the vessel, and that no vapours pass off: Do not heat any part of the test portion of the sample to a temperature higher than 50 C above the expected softening point. Remove air bubbles from the melt by carefully stirring, and remove any foam developing on the surface of the melt. Foam is
27、an indication of water in the pitch. Keep the sample at the same temperature until foaming ends. Prepare the surface of the plate (4.3) by rubbing the release agent (4.5) onto the surface of the plate. Place the sample cup (4.1.2) onto the prepared surface of the plate. Take the bowl and molten test
28、 sample (6.1) and fill the sample cup by pouring the molten material from the bowl into the cup, such that it protrudes above the top of the sample cup by 1 mm to 2 mm. After cooling, level the sample surface with the warmed knife or spatula to become flush with the upper rim of the sample cup. Take
29、 care to avoid hollow spaces in the sample: do not simply cut away the protruding part of the sample. Remove the cup from the plate. BS ISO 5940-2:2007 5 6.3 Preparation of pitch by pressing Grind the sample so that the particle fraction ranges from 1 mm to 2 mm. Insert the sample cup in the cartrid
30、ge assembly and fill the cup with ground material, use the punch to press the material in the cup slightly by hand, then insert the cartridge assembly in the hydraulic mould. Apply a force of 15 kN to the sample in the cup for at least 15 s. Remove the assembly from the mould; and loosen the sample
31、cup by tapping the head of the punch. Be aware that the temperatures at the measured softening points are lower by up to 1 C, when using this procedure. 7 Procedure 7.1 Placing the sample in the apparatus Assemble the filled sample cup with the sample cup holder and the collector sleeve to make a ca
32、rtridge. 7.2 Operating the testing apparatus and expression of results Choose a temperature 20 C to 25 C below the expected softening point as a starting temperature. Adjust the equipment to a heating rate of 2 C per min. As soon as it is indicated that the apparatus is ready for operation, place th
33、e cartridge with the sample into the furnace and rotate until the collector sleeve is engaged. About 30 s later start the apparatus. At the end of the determination, the Mettler softening point is read from the storage of results on the apparatus, in degrees Celsius, to the nearest 0,1 C. Rounding t
34、o the last significant decimal place shall be done in accordance with DIN 1333. 7.3 Calibrating the temperature 7.3.1 Using a thermometer or thermocouple The temperature indication at the operating unit can be verified as follows: The ball of a suitable thermometer or the tip of a thermocouple is pu
35、t into the sample cup and cast with pitch. Then the lower part of the sample holder, with the sample cup and thermometer or thermocouple, is put into the furnace and heated to a definite temperature. 5 min after the selected temperature is reached, the reading of the suitable thermometer or thermoco
36、uple shall be not more than 0,5 C below the reading of the resistance thermometer (4.1.3) on the control unit. After a longer duration, the difference of the readings should approach zero. If the furnace is heated with a constant temperature rate of 2 C/min (as in the procedure for determining the s
37、oftening point), the suitable thermometer or thermocouple can be expected to indicate a temperature 1 C to 1,5 C less than the control unit. 7.3.2 Using benzoic acid on units with a calibration program This test can be run every quarter or half year, or after adjustments. Place the test-portion hold
38、er on an even surface and fill with benzoic acid. Pack firmly using a 10 mm diameter glass rod. Select the calibration program and run the analysis, but with a start temperature of 121 C and a temperature increase of 0,2 C/min. The results should be 123,5 0,5 C. If not, the apparatus must be adjuste
39、d. NOTE Pitch on the outside of the sample cup or inside the furnace will fume during the measurement and the fumes can disturb the photocell. This can cause a measurement result that is too low. BS ISO 5940-2:20076 8 Test report The test report shall include the following information: a) a referenc
40、e to this part of ISO 5940; b) any agreed deviations from this part of ISO 5940; c) the date of the test; d) details necessary for the complete identification of the material tested; e) type of material tested, e.g. grindable pitch or non-grindable pitch; f) whether the sample was pressed, or poured
41、 in the melted state into the cup; g) the type of Mettler apparatus used and its manufacturer; h) the number of test specimens; i) the individual values and the mean value, in degrees Celsius, for the Mettler softening point, as indicated by the digital readout, to the nearest 0,1 C. 9 Precision 9.1
42、 Determination The precision was determined in accordance with DIN 51848-1. 9.2 Repeatability The difference between two results, collected on the same sample by the same person with the same instrument under constant analysis conditions, is regarded as acceptable, and in conformity with this part o
43、f ISO 5940, if the difference is not larger than 0,5 C. 9.3 Reproducibility The difference between two single and independent results, collected on identical samples by different persons in different laboratories, is regarded as acceptable, and in conformity with this part of ISO 5940, if they diffe
44、r by not more than 1,5 C. BS ISO 5940-2:2007 7 Annex A (informative) Approximate comparison with softening points determined by other methods The Mettler softening point (M SP ) can be compared approximately with softening points obtained by other methods by applying the following conversion factors
45、: DIN 52025, Kraemer-Sarnow softening point, () SP 13 0,95 KS M = DIN 52011, Softening point ring and ball, SP 5 RB M = ASTM D 2319, Softening point cube-in-air, SP CA M = where M SPis the Mettler softening point;KS is the Kraemer-Sarnow softening point; RB is the softening point for ring and ball;
46、CA is the cube-in-air softening point. BS ISO 5940-2:20078 Bibliography 1 DIN 52011, Testing of bitumen Determination of the softening point ring and ball 2 DIN 52025, Testing of carbonaceous materials Determination of the Kraemer-Sarnow softening point 3 ASTM D2319-98, Standard Test method for Soft
47、ening Point of Pitch (Cube-in-Air Method) 4 ASTM D3104-99 (2005), Standard Test Method for Softening Point of Pitches (Mettler Softening Point Method) BS ISO 5940-2:2007 blankBS ISO 5940-2:2007 BSI 389 Chiswick High Road London W4 4AL BSI British Standards Institution BSI is the independent national
48、 body responsible for preparing British Standards. It presents the UK view on standards in Europe and at the international level. It is incorporated by Royal Charter. Revisions British Standards are updated by amendment or revision. Users of British Standards should make sure that they possess the l
49、atest amendments or editions. It is the constant aim of BSI to improve the quality of our products and services. We would be grateful if anyone finding an inaccuracy or ambiguity while using this British Standard would inform the Secretary of the technical committee responsible, the identity of which can be found on the inside front cover. Tel: +44 (0)20 8996 9000. Fax: +44 (0)20 8996 7400. BSI offer
