1、Reference number ISO 12981-1:2000(E) ISO 2000 INTERNATIONAL STANDARD ISO 12981-1 First edition 2000-11-01 Carbonaceous materials used in the production of aluminium Calcined coke Determination of the reactivity to carbon dioxide Part 1: Loss in mass method Produits carbons utiliss pour la production
2、 de laluminium Coke calcin Dtermination de la ractivit au dioxyde de carbone Partie 1: Mthode par perte de masseISO 12981-1:2000(E) PDF disclaimer This PDF file may contain embedded typefaces. In accordance with Adobes licensing policy, this file may be printed or viewed but shall not be edited unle
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7、 in Switzerland ii ISO 2000 All rights reservedISO 12981-1:2000(E) ISO 2000 All rights reserved iii Contents Page Foreword.iv Introduction.v 1 Scope 1 2 Normative references 1 3 Principle1 4 Reagent.1 5 Apparatus .2 6 Sampling.5 7 Preparation of test sample6 8 Procedure .6 9 Expression of results 7
8、10 Precision.7 11 Test report 7ISO 12981-1:2000(E) iv ISO 2000 All rights reserved Foreword 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 throu
9、gh ISO technical committees. Each member body interested in a subject for 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 collabora
10、tes closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 3. Draft International Standards adopted by the technical committees are cir
11、culated 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 part of ISO 12981 may be the subject of patent rights. ISO shall not be he
12、ld responsible for identifying any or all such patent rights. International Standard ISO 12981-1 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 12981 co
13、nsists of the following parts, under the general title Carbonaceous materials used in the production of aluminium Calcined coke Determination of the reactivity to carbon dioxide: Part 1: Loss in mass method Part 2: Thermogravimetric methodISO 12981-1:2000(E) ISO 2000 All rights reserved v Introducti
14、on The reactivity of a calcined coke to carbon dioxide is assessed by determining the loss in mass of a sample exposed in accordance with the following chemical reaction: C CO 2 2C O This determination allows an assessment of the later anode reactivity to carbon dioxide in the electrolysis cell.INTE
15、RNATIONAL STANDARD ISO 12981-1:2000(E) ISO 2000 All rights reserved 1 Carbonaceous materials used in the production of aluminium Calcined coke Determination of the reactivity to carbon dioxide Part 1: Loss in mass method 1 Scope This part of ISO 12981 specifies a method for the determination, by a l
16、oss in mass method, of the reactivity of calcined petroleum coke, used in the manufacture of anodes for the production of aluminium, to carbon dioxide. 2 Normative references The following normative documents contain provisions which, through reference in this text, constitute provisions of this par
17、t of ISO 12981. For dated references, subsequent amendments to, or revisions of, any of these publications do not apply. However, parties to agreements based on this part of ISO 12981 are encouraged to investigate the possibility of applying the most recent editions of the normative documents indica
18、ted below. For undated references, the latest edition of the normative document referred to applies. Members of ISO and IEC maintain registers of currently valid International Standards. ISO 383, Laboratory glassware Interchangeable conical ground joints. ISO 5725-2, Accuracy (trueness and precision
19、) of measurement methods and results Part 2: Basic method for the determination of repeatability and reproducibility of a standard measurement method. ISO 6375, Carbonaceous materials for the production of aluminium Coke for electrodes Sampling. ISO 8723, Carbonaceous materials for the production of
20、 aluminium Calcined coke Determination of oil content Method by solvent extraction. ISO 12984, Carbonaceous materials used in the production of aluminium Calcined coke Determination of particle size distribution. 3P r i n c i p l e A coke sample of 5 g having a grain size of 1 mm to 1,4 mm is expose
21、d to a carbon dioxide (CO 2 ) stream of 50 l/h for approximately 100 min at 1 000 C. The loss in mass is then measured. 4 Reagents 4.1 CO 2 , having a minimum purity of 99,9 % by volume and maximum impurity levels of O 2 : 100 mol/mol, H 2 O: 130 mol/mol, N 2 + Ar: 800 mol/mol.ISO 12981-1:2000(E) 2
22、ISO 2000 All rights reserved 4.2 Calibration standard, certified with a precisely known value of reactivity to carbon dioxide of about 10 % by mass. NOTE Suitable materials are commercially available. 5 Apparatus A diagram of a complete apparatus is shown in Figure 1. 5.1 Ordinary laboratory apparat
23、us. 5.2 Furnace, with a vertical, single-zone tube ensuring good vertical temperature distribution and capable of heating from 20 Ct o10 00C in less than 1 h and maintaining the temperature at (1 000 3) C. The characteristics and dimensions of a typical furnace are shown in Figure 2. 5.3 Tube reacto
24、r, consisting of two quartz tubes and a cap, with ground-glass joints (ISO 383, NS 29/32). The characteristics and dimensions of a typical tube reactor assembly are shown in Figure 3 with the following components: 5.3.1 External tube, containing a) a gas inlet, positioned at the top of the external
25、tube, allowing the gas to flow down to the bottom of the tube and to be preheated before flowing up through the coke bed; b) a protection tube for the thermocouple positioned so that the tip of the thermocouple lies 5 mm underneath the fritted disc. The bottom of the thermocouple protection tube and
26、 the gas inlet shall be external to the furnace. 5.3.2 Inner reaction tube, fitted inside the external tube. 5.3.3 Fritted disc, having a 250 mm to 500 mm pore size, fitted inside the inner reaction tube and positioned so that the base of the coke bed lies in the middle of the furnace. 5.3.4 Cap, co
27、ntaining a gas outlet, clamped to the top of the inner reaction tube. 5.4 Thermocouple, chromel alumel, K-type, having an accuracy of better than 0,375 %, a diameter of 2 mm and a minimum length of 200 mm. 5.5 Temperature control unit, consisting of a two-point temperature PID controller with a set-
28、value adjuster (adjustment error 0,5 %) and with a digital temperature display. The set-point value shall be selected so that the tube reactor thermocouple indicates 1 000 C. 5.6 Flow meter, with a calibrated scale, for the CO 2 (p = 0,1 MPa), having a full-scale reading of 60 l/h and an accuracy of
29、 better than 2%. 5.7 Pressure control, comprising a valve to regulate the pressure, and a manometer having a scale reading from of 0 MPa to 1,0 MPa.ISO 12981-1:2000(E) ISO 2000 All rights reserved 3 Figure 1 CO 2 reactivity apparatusISO 12981-1:2000(E) 4 ISO 2000 All rights reserved Dimensions in mi
30、llimetres Figure 2 Characteristics and dimensions of a typical furnaceISO 12981-1:2000(E) ISO 2000 All rights reserved 5 Dimensions in millimetres Key 1C O 2 in 2C O 2 out 3 Test sample (5 g) Figure 3 Tube reactor with test sample 6 Sampling Take a sample of the coke in accordance with the procedure
31、 specified in ISO 6375.ISO 12981-1:2000(E) 6 ISO 2000 All rights reserved 7 Preparation of test sample Divide the sample (see clause 6) into three fractions by sieving in accordance with ISO 12984. The fractions shall have the following dimensions: I 1,4 mm; IIa 1 mm to 1,4 mm; III 1 mm. Crush fract
32、ion I to produce fraction llb so that most of fraction llb has the following dimensions after sieving: l l b 1mmto1 ,4mm. Thoroughly mix fractions IIa and llb. Many granular materials are coated with oil. In such cases, remove the oil from the mixture of fractions IIa and IIb with dichloromethane, u
33、sing the procedure specified in ISO 8723. Dry the mixture of fractions IIa and llb at (110 5) C to constant mass, i.e. until consecutive weighings at 5 min intervals differ by less than 0,1 %. Take a test sample of (5 0,01) g from the mixture of fractions IIa and IIb and weigh it to the nearest 0,00
34、1 g. 8 Procedure 8.1 Calibration Calibrate the apparatus once a week and after any maintenance of the apparatus, for instance replacement of the reaction tube or thermocouple. Set the reaction time to 100 min. Carry out two measurements using the calibration standard (4.2) and calculate the average
35、result (see clause 9). Calibrate the apparatus by calculating the reaction time, t r , in accordance with the following equation: t w w r RC,cal RC,meas 100 = where w RC,cal is the certified value of the reactivity of the calibration standard, expressed as a mass fraction in percent; w RC,meas is th
36、e measured value of the reactivity of the calibration standard to carbon dioxide, expressed as a mass fraction in percent. 8.2 Determination Switch on the furnace and set the temperature control unit (5.5) to 1 000 C. Insert the empty inner reaction quartz tube (5.3.2) and fix the cover with the cla
37、mp. Open the CO 2 gas valve and regulate the pressure to 0,2 MPa and the flow rate to 50 l/h. When the furnace temperature has stabilized to (1 000 3) C, insert the weighed test sample into the reaction tube. After the reaction time has passed, switch off the furnace. After a further 30 min, stop th
38、e CO 2 gas, remove the reaction tube, and place it in a holder to cool. When the reaction tube has cooled, weigh the remaining test sample to the nearest 0,001 g.ISO 12981-1:2000(E) ISO 2000 All rights reserved 7 9 Expression of results Calculate the value of the reactivity to carbon dioxide w RC ,
39、expressed as a mass fraction in percent, in accordance with the following formula: w RC = mm m 01 0 100 where m 0 is the initial mass, expressed in grams, of the test sample before reaction with carbon dioxide; m 1 is the final mass, expressed in grams, of the test sample after reaction with carbon
40、dioxide. 10 Precision 10.1 Interlaboratory study A series of tests were carried out in accordance with ISO 5725-2 to determine the precision data. In 1993 samples were tested in over 20 laboratories, giving the following results. 10.2 Repeatability The difference between the values of duplicate dete
41、rminations, carried out in rapid succession by the same operator using the same apparatus on the same laboratory sample, is not expected to exceed the following repeatability limit r = 7 % (relative) 10.3 Reproducibility The difference between the values of the average of duplicate determinations ob
42、tained with two laboratories using this method for the analysis of the same laboratory sample is not expected to exceed the following reproducibility limit R = 15 % (relative) 11 Test report The test report shall include the following information: a) an identification of the sample; b) the method us
43、ed with reference to this part of ISO 12981; c) the date of the test and the results, expressed in accordance with clause 9; d) any unusual features noted during the determination; e) any operation not included in this part of ISO 12981 or in the International Standards to which reference is made, or regarded as optional; f) the name and address of the certifying organization for the calibration standard.ISO 12981-1:2000(E) ICS 71.100.10 Price based on 7 pages ISO 2000 All rights reserved
