1、BRITISH STANDARD BS ISO 12988-2:2004 Carbonaceous materials used in the production of aluminium Baked anodes Determination of the reactivity to carbon dioxide Part 2: Thermogravimetric method ICS 71.100.10 BS ISO 12988-2:2004 This British Standard was published under the authority of the Standards P
2、olicy and Strategy Committee on 1 December 2004 BSI 1 December 2004 ISBN 0 580 44925 4 National foreword This British Standard reproduces verbatim ISO 12988-2:2004 and implements it as the UK national standard. The UK participation in its preparation was entrusted to Technical Committee CII/24, Raw
3、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 in the
4、 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 responsible f
5、or 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 UK in
6、terests 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 12, an inside back cover and a back cover. The BSI copyr
7、ight notice displayed in this document indicates when the document was last issued. Amendments issued since publication Amd. No. Date Comments Reference number ISO 12988-2:2004(E) OSI 4002INTERNATIONAL STANDARD ISO 12988-2 First edition 2004-09-15 Carbonaceous materials used in the production of alu
8、minium Baked anodes Determination of the reactivity to carbon dioxide Part 2: Thermogravimetric method Produits carbons utiliss pour la production de laluminium Anodes cuites Dtermination de la ractivit au dioxyde de carbone Partie 2: Mthode thermogravimtrique BSISO129882:2004IS-88921 O2:(4002E) DPl
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13、o yr ttseuqer 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-mial coirypthgis.o gro We bwww.is.o groii ISO 4002 Allr ithgsr esedevrBSISO129882:2004IS-88921 O2:(4002E) I SO 4002 All irthgs ersedevr iiiContents Page Foreword iv Introductio
14、n v 1 Scope 1 2 Normative references . 1 3 Terms and definitions. 1 4 Principle . 2 5 Apparatus. 2 6 Reagents 5 7 Sample 5 8 Calibration 5 9 Procedure. 7 10 Calculation of results 7 11 Precision and bias 9 12 Test report 11 Bibliography . 12 BSISO129882:2004IS-88921 O2:(4002E) iv I SO 4002 All irthg
15、s ersedevrForeword ISO (the International Organization for 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
16、 which a technical committee has been established has the 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 the International Electrotechnical Commission (IEC) on a
17、ll matters of electrotechnical standardization. International 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
18、 circulated to the member bodies for voting. Publication as an 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 re
19、sponsible for identifying any or all such patent rights. ISO 12988-2 was prepared by Technical Committee ISO/TC 47, Chemistry, Subcommittee SC 7, Aluminium oxide, cryolite, aluminium fluoride, sodium fluoride, carbonaceous products for the aluminium industry. ISO 12988 consists of the following part
20、s, under the general title Carbonaceous materials used in the production of aluminium Baked anodes Determination of the reactivity to carbon dioxide: Part 1: Loss in mass method Part 2: Thermogravimetric method BSISO129882:2004IS-88921 O2:(4002E) I SO 4002 All irthgs ersedevr vIntroduction The CO 2r
21、eactivities, or reaction rates, are used to quantify the tendency of a carbon artifact to react with carbon dioxide. Carbon consumed by these unwanted side reactions is unavailable for the primary reactions of reducing alumina to the primary metal. CO 2reactivities and dusting rates are used to quan
22、tify the tendency of the coke aggregate or binder coke of a carbon artifact to selectively react with these gases. Preferential attack of the binder coke or coke aggregate of a carbon artifact by these gases causes some carbon to fall off or dust, making the carbon unavailable for the primary reacti
23、on of reducing alumina and, more importantly, reducing the efficiency of the aluminium reduction cell. Comparison of CO 2reactivities and dusting rates is useful in selecting raw materials for the manufacture of commercial anodes for specific smelting technologies in the aluminium reduction industry
24、. CO 2reactivities are used for evaluating effectiveness and beneficiation processes, or for research purposes. Sampling guidelines are under development. This part of ISO 12988 is based on ASTM D 6558-00. BSISO129882:2004blank 4002:288921OSISBINTENRATIONAL TSANDADR IS-88921 O2:(4002E)I SO 4002 All
25、irthgs ersedevr 1Carbonaceous materials used in the production of aluminium Baked anodes Determination of the reactivity to carbon dioxide Part 2: Thermogravimetric method WARNING This part of ISO 12988 does not purport to address all of the safety concerns, if any, associated with its use. It is th
26、e responsibility of the user of this part of ISO 12988 to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. 1 Scope This test method covers the thermogravimetric (TGA) determination of CO 2reactivities and dusting of shaped carb
27、on anodes used in the aluminium reduction industry. Many types of apparatus are available with a wide variety of thermal conditions, sample-size capability, materials of construction and procedures for determining the mass loss and subsequent rate of reaction. This test method standardizes the varia
28、bles of sample dimensions, reaction temperature, gas velocity over the exposed surfaces, and reaction time such that results obtained on different types of apparatus are correlatable. 2 Normative references The following referenced documents are indispensable for the application of this document. Fo
29、r dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ASTM E 691-99, Standard Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method 3 Terms and definitions F
30、or the purposes of this part of ISO 12988, the following terms and definitions apply. 3.1 dusting a RCDthat quantity of carbon that falls off the carbon artifact during the test and is collected in the container at the bottom of the reaction chamber 3.2 final CO 2reactivity a RCfrate of mass loss of
31、 the carbon artifact during the final 30 min of exposure to CO 2in the reaction chamber divided by the initial geometric (right cylindrical) exposed surface area of the sample NOTE The final CO 2reactivity is expressed in milligrams per square centimetre per hour. BSISO129882:2004IS-88921 O2:(4002E)
32、 2 I SO 4002 All irthgs ersedevr3.3 initial CO 2reactivity a RCirate of mass loss of the carbon artifact during the first 30 min of exposure to CO 2in the reaction chamber divided by the initial geometric (right cylindrical) exposed surface area of the sample NOTE The initial CO 2reactivity is expre
33、ssed in milligrams per square centimetre per hour. 3.4 total CO 2reactivity a RCtrate of mass loss of the carbon artifact (including dusting) during the total time that the sample is exposed to CO 2(420 min) in the reaction chamber divided by the initial geometric (right cylindrical) exposed surface
34、 area of the sample NOTE The total CO 2reactivity is expressed in milligrams per square centimetre per hour. 4 Principle The dusting rate and the initial, final and total CO 2reactivities are determined by passing carbon dioxide gas at a flow rate that gives a standard velocity of reactant gas aroun
35、d cylindrically shaped carbon artifacts under isothermal conditions for a specified length of time. The reactivity is determined by continuously monitoring the sample mass loss. The CO 2dusting rate is determined by collecting and determining the mass of carbon particles that fall off the sample dur
36、ing reaction. 5 Apparatus The apparatus to be used should be as simple as possible and be commensurate with what is to be achieved. The principal criterion is that the reaction rate be determined under isothermal conditions and be unaffected by physical and chemical properties inherent to the appara
37、tus (such as gas diffusion patterns, gas temperature, exposed sample surface area, and so forth). A typical apparatus that has been found to be suitable is illustrated in Figure 1. 5.1 Furnace and controller, capable of maintaining constant temperature, within 2 C in the 100-mm reaction zone in whic
38、h the sample is centred. A typical apparatus, as illustrated in Figure 1, employs a three-zone heating element and associated 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 sha
39、ll be located within the reaction chamber near the surface of the test sample. This is to allow the furnace controller 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 surfa
40、ce of the sample and within 5 mm vertically of the centre of the reaction chamber. The furnace shall be large enough to accommodate the reaction chamber. 5.2 Reaction chamber, consisting of a vertical tube constructed of a material capable of withstanding the temperature of the reaction, e.g. 960 C
41、2 C with a sufficiently large inside diameter to accommodate the sample and sample suspension device while not affecting the gas flow 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 capab
42、le of capturing all the dust that falls off the sample during the test. The most common materials of construction are quartz and Inconel 1) . 1) Inconel is an example of a suitable product available commercially. This information is given for the convenience of users of this part of ISO 12988 and do
43、es not constitute an endorsement by ISO of this product.BSISO129882:2004IS-88921 O2:(4002E) I SO 4002 All irthgs ersedevr 35.3 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 holder shall not cha
44、nge in mass during the test, shall not affect the flow pattern of the gas past the sample, shall not 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 holder is illustrated in Figure 2. Dimensions in millimetr
45、es Key 1 balance 9 dust-collection cup 2 gas outlet (10 mm hole) 10 gas inlet 3 three-zone furnace 11 air or CO 24 connecting wire (see Figure 2) 12 N 25 reaction chamber 13 pressure-reducing valve 6 sample 14 needle valve 7 control thermocouple 15 flow meter 8 preheat tube Figure 1 Typical CO 2reac
46、tivity apparatus BSISO129882:2004IS-88921 O2:(4002E) 4 I SO 4002 All irthgs ersedevrDimensions in millimetres Key 1 suspension wire (Nichrome 2) ) 3 cylindrical sample 2 sample support wire (platinum, 1 mm diameter) 4 stainless steel ball Figure 2 Typical sample suspension arrangement 5.4 Gas prehea
47、t tube, extending into the first heating zone of the reaction chamber, to preheat the gas prior to entering the reaction 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 prehea
48、t tube downward to prevent channelling of the gas through the reaction chamber and to prevent plugging of the preheat tube with carbon dust. 5.5 Balance, capable of measuring the mass (approximately 200 g maximum) of the sample and sample suspension device to the nearest 0,01 g continuously througho
49、ut the duration of the test. 5.6 Gas flow meter, capable of measuring the flow rate of the gas entering the reaction chamber. All gas flow rates shall be maintained at the rate determined for the particular test apparatus. 5.7 Needle valve, to make fine adjustments to the gas flow rate. 2) Nichrome is an example of a suitable product available commercially. This information is given for the convenien
