BS ISO 12989-2-2005 Carbonaceous materials used in the production of aluminium - Baked anodes and sidewall blocks - Determination of the reactivity to air - Thermogravimetric metho.pdf

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1、BRITISH STANDARD BS ISO 12989-2:2004 Carbonaceous materials used in the production of aluminium Baked anodes and sidewall blocks Determination of the reactivity to air Part 2: Thermogravimetric method ICS 71.100.10 BS ISO 12989-2:2004 This British Standard was published under the authority of the St

2、andards Policy and Strategy Committee on 29 March 2005 BSI 29 March 2005 ISBN 0 580 45702 8 National foreword This British Standard reproduces verbatim ISO 12989-2:2004 and implements it as the UK national standard. The UK participation in its preparation was entrusted to Technical Committee CII/24,

3、 Raw materials for the aluminium industry, which has the responsibility to: A list of organizations represented on this committee can be obtained on request to its secretary. Cross-references The British Standards which implement international publications referred to in this document may be found i

4、n the BSI Catalogue under the section entitled “International Standards Correspondence Index”, or by using the “Search” facility of the BSI Electronic Catalogue or of British Standards Online. This publication does not purport to include all the necessary provisions of a contract. Users are responsi

5、ble for its correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. 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

6、UK interests informed; monitor related international and European developments and promulgate them in the UK. Summary of pages This document comprises a front cover, an inside front cover, the ISO title page, pages ii to v, a blank page, pages 1 to 13 and a back cover. The BSI copyright notice displ

7、ayed in this document indicates when the document was last issued. Amendments issued since publication Amd. No. Date Comments Reference number ISO 12989-2:2004(E) OSI 4002INTERNATIONAL STANDARD ISO 12989-2 First edition 2004-05-15 Carbonaceous materials used in the production of aluminium Baked anod

8、es and sidewall blocks Determination of the reactivity to air Part 2: Thermogravimetric method Produits carbons utiliss pour la production de laluminium Anodes et blocs de faade cuits Dtermination de la ractivit lair Partie 2: Mthode thermogravimtrique BSISO129892:2004IS-98921 O2:(4002E) DPlcsid Fre

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13、euqer ehe.r ISO cirypothg fofice saCe tsopale 65 eneG 1121-HC 02 av leT. 4 + 10 947 22 1 11 xaF0 947 22 14 + 9 74 E-mail coirypthgiso.o gr We bwww.is.o gro Pulbisdehi n Switlrez dnaii ISO 4002 Allr ithgsr esedevrBSISO129892:2004IS-98921 O2:(4002E) I SO 4002 All irthgs ersedevr iiiContents Page Forew

14、ord iv Introduction v 1 Scope 1 2 Terms and definitions. 1 3 Principle. 2 4 Apparatus. 2 5 Reagents 3 6 Sample 3 7 Calibration 4 8 Procedure. 5 9 Calculation of results 6 9.1 Exposed surface area of the sample. 6 9.2 Total air reactivity . 6 9.3 Initial air reactivity. 6 9.4 Final air reactivity 7 9

15、.5 Air dusting rate 7 10 Precision and bias 7 10.1 Precision 7 10.2 Repeatability 7 10.3 Reproducibility limits 9 10.4 Bias. 10 11 Test report 10 Bibliography . 13 BSISO129892:2004IS-98921 O2:(4002E) iv I SO 4002 All irthgs ersedevrForeword ISO (the International Organization for Standardization) is

16、 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 right to be represen

17、ted 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 Standards are dr

18、afted 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 International S

19、tandard 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 12989-2 was prepa

20、red by Technical Committee ISO/TC 47, Chemistry, Subcommittee SC 7, Aluminium oxide, cryolite, aluminium fluoride, sodium fluoride, carbonaceous products for the aluminium industry. ISO 12989 consists of the following parts, under the general title Carbonaceous materials used in the production of al

21、uminium Baked anodes and sidewall blocks Determination of the reactivity to air: Part 1: Loss in mass method Part 2: Thermogravimetric method BSISO129892:2004IS-98921 O2:(4002E) I SO 4002 All irthgs ersedevr vIntroduction Comparison of air reactivities, or air reaction rates, and air dusting rates i

22、s useful in selecting raw materials for the manufacture of commercial electrodes for specific smelting technologies in the production of aluminium. Air reactivities are used to quantify the tendency of a carbon artifact to react with air. Carbon consumed by this unwanted side reaction is unavailable

23、 for the primary reaction of reducing alumina to the metal. Air reactivities and the dusting rate are used by some companies to quantify the tendency of the coke aggregate or binder coke of a carbon artifact to selectively react with air. Preferential attack of the binder coke or coke aggregate of a

24、 carbon artifact by air causes some carbon to fall off as dust, making the carbon unavailable for the primary reaction of reducing alumina and, more importantly, reducing the efficiency of the reduction cell. Air reactivities are used for evaluating the effectiveness of beneficiation processes and f

25、or research purposes. Sampling guidelines are under development. This part of ISO 12989 is based on ASTM D 6559-00. BSISO129892:2004blank 4002:298921OSISBINTENRATIONAL TSANDADR IS-98921 O2:(4002E)I SO 4002 All irthgs ersedevr 1Carbonaceous materials used in the production of aluminium Baked anodes a

26、nd sidewall blocks Determination of the reactivity to air Part 2 Thermogravimetric method WARNING This part of ISO 12989 does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this part of ISO 12989 to establish appropriate sa

27、fety and health practices and determine the applicability of regulatory limitations prior to use. 1 Scope This part of ISO 12989 allows the determination by thermogravimetric analysis (TGA) of air reactivities and dusting of shaped carbon electrodes used in the aluminium-reduction industry. Many typ

28、es of apparatus are available, with various thermal conditions, sample-size capabilities, materials of construction and procedures for determining the mass loss and subsequent rate of reaction. This test method standardizes the variables of sample dimensions, reaction times and temperatures, and pro

29、vides a mathematical method to normalize the gas velocity over the exposed surfaces, such that results obtained on different types of apparatus are correlatable. 2 Terms and definitions For the purposes of this document, the following terms and definitions apply. 2.1 air dusting rate dnormalized rat

30、e at which carbon falls off the carbon artifact during the test NOTE The dusting rate is expressed in milligrams per square centimetre per hour. 2.2 final air reactivity frate of mass loss of the carbon artifact during the final 30 min of exposure to air in the reaction chamber divided by the initia

31、l exposed surface area of a sample having the form of a right cylinder NOTE The final air reactivity is expressed in milligrams per square centimetre per hour. 2.3 initial air reactivity irate of mass loss of the carbon artifact during the first 30 min of exposure to air in the reaction chamber divi

32、ded by the initial exposed surface area of a sample having the form of a right cylinder NOTE The initial air reactivity is expressed in milligrams per square centimetre per hour. BSISO129892:2004ISO 12989-2:2004(E) 2 I SO 4002 All irthgs ersedevr2.4 total air reactivity Trate of mass loss of the car

33、bon artifact (including dusting) during the total time that the sample is exposed to air (180 min) in the reaction chamber divided by the initial exposed surface area of a sample having the form of a right cylinder NOTE The total air reactivity is expressed in milligrams per square centimetre per ho

34、ur. 3 Principle The air dusting rate and the initial, final and total air reactivities are determined by passing air at a flow rate giving a standard velocity of reactant gas around cylindrically shaped carbon artifacts under nearly isothermal conditions for a specified length of time. The air react

35、ivities are determined by continuously monitoring the mass loss of the sample. The air dusting rate is determined by collecting and determining the mass of the carbon particles that fall off the sample during reaction. 4 Apparatus 4.1 Air reactivity apparatus, as simple as possible and commensurate

36、with the aims of the test. The principal criterion is that the reaction rate be determined under isothermal conditions and be unaffected by physical and chemical properties inherent in the apparatus (such as gas diffusion patterns, gas temperature, exposed sample surface area, and so forth). A typic

37、al apparatus that has been found to be suitable is illustrated in Figure 1. 4.2 Furnace and controller, capable of maintaining the temperature constant to within 2 C in the 100-mm reaction zone in which the sample is centred. A typical apparatus (Figure 1) employs a three-zone heating element and as

38、sociated controls to accomplish this, but other types of heaters such as tapered windings or long linear heaters are also suitable. The control thermocouple is a grounded type and shall be located within the reaction chamber near the surface of the test sample. This is to allow the furnace controlle

39、r to compensate for the exothermic reactions that occur when the furnace is used for air reactivity testing. The control thermocouple shall be positioned 4 mm 1 mm from the side surface of the sample and within 5 mm vertically of the centre of the reaction chamber. The furnace shall be large enough

40、to accommodate the reaction chamber. 4.3 Reaction chamber, consisting of a vertical tube constructed of a material capable of withstanding the temperature of the reaction and with a sufficiently large inside diameter to accomodate the sample and sample suspension device while not affecting the gas f

41、low past the sample. An inside diameter of 100 mm 25 mm is recommended. The reaction chamber shall be constructed with a removable dust collection cup at the bottom capable of capturing all the dust that falls off the sample during the test. The most common materials of construction are quartz and I

42、ncone 1) . 4.4 Sample suspension device, capable of supporting the sample in the reaction chamber for the duration of the test and which should be reusable. The sample suspension device shall not change in mass during the test, shall not affect the flow pattern of the gas past the sample, shall not

43、limit the gas-accessible surface area of the test sample and shall not interfere with the production of dust by the sample. A typical sample suspension device is illustrated in Figure 2. 1) Inconel is an example of a suitable product available commercially. This information is given for the convenie

44、nce of users of this part of ISO 12989 and does not constitute an endorsement by ISO of this product. BSISO129892:2004IS-98921 O2:(4002E) I SO 4002 All irthgs ersedevr 34.5 Gas preheat tube, extending into the first heating zone of the reaction chamber, to preheat the gas prior to entering the react

45、ion chamber. The length and diameter of the tube may vary, as long as the gas leaving the tube is at the same temperature as the reaction chamber. The inlet gas shall leave the preheat tube downward to prevent channelling of the gas through the reaction chamber and to prevent plugging of the preheat

46、 tube with carbon dust. 4.6 Balance, capable of measuring the mass (approximately 200 g maximum) of the sample and sample suspension device to the nearest 0,01 g continuously throughout the duration of the test. 4.7 Gas flow meter, capable of measuring the flow rate of the gas entering the reaction

47、chamber. All gas flow rates shall be maintained at the rate specified for the particular test apparatus. 4.8 Needle valve, to make fine adjustments to the gas flow rate. 4.9 Pressure-reducing valve, to reduce the pressure of the compressed gas to near atmospheric pressure before it enters the gas fl

48、ow meter. 4.10 Thermocouple(s), (for example, three couples in the same sheath with probes located at the tip, and at 50 mm and 100 mm above the tip; or a packet of thermocouples with tips located at similar known distances) capable of being inserted into the reaction chamber to calibrate the furnac

49、e zone controllers. An optional thermocouple may be used to monitor reaction temperatures. Some users find continuous temperature measurement of the central part of the reaction chamber to be of value. 4.11 Callipers, or other suitable device, capable of measuring the sample diameter and height to within 0,01 mm to calculate the geometric surface area exposed to the test gas. 4.12 Optional equipment, inc