1、 Reference number ISO 806:2004(E) ISO 2004INTERNATIONAL STANDARD ISO 806 Second edition 2004-10-15 Aluminium oxide primarily used for the production of aluminium Determination of loss of mass at 300 C and 1 000 C Oxyde daluminium principalement utilis pour la production de laluminium Dtermination de
2、 la perte de masse 300 C et 1 000 C ISO 806:2004(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 unless the typefaces which are embedded are licensed to and installed on the compute
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5、ntral Secretariat at the address given below. ISO 2004 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO
6、 at the address below or ISOs member body in the country of the requester. ISO copyright office Case postale 56 CH-1211 Geneva 20 Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail copyrightiso.org Web www.iso.org Published in Switzerland ii ISO 2004 All rights reservedISO 806:2004(E) ISO 2004 All
7、rights reserved iiiForeword 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 su
8、bject 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 collaborates closely with the International Electrotechnical Commission (
9、IEC) on all 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 commi
10、ttees are 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 b
11、e held responsible for identifying any or all such patent rights. ISO 806 was prepared by Technical Committee ISO/TC 226, Materials for the production of primary aluminium. This second edition cancels and replaces the first edition (ISO 806:1976) together with ISO 803:1976, which have been technical
12、ly revised. This International Standard is based on AS 2879.1-2000 prepared by the Standards Australia Committee MN/9, Alumina and Materials used in Aluminium Production, as a revision of AS 2879:1986, Alumina Determination of loss of mass at 300 C and 1 000 C. ISO 806:2004(E) iv ISO 2004 All rights
13、 reservedIntroduction The objective of this revision is to incorporate sample preparation procedures, improve the description of the method and to provide a method for determination of loss of mass by automatic procedures. INTERNATIONAL STANDARD ISO 806:2004(E) ISO 2004 All rights reserved 1Aluminiu
14、m oxide primarily used for the production of aluminium Determination of loss of mass at 300 C and 1 000 C 1 Scope This International Standard specifies a method for the determination of loss of mass on heating of aluminium oxide at 300 C and further loss of mass on ignition at 1 000 C. By industry c
15、onvention, these mass losses are often referred to as “moisture (MOI)” and “loss on ignition (LOI)” respectively. This method is suitable for calcined alumina in the range 0,2 % to 5 % loss of mass at 300 C and 0,1 % to 2 % loss of mass at 1 000 C. This method provides for samples to be treated on a
16、n “as-received” basis for determination of actual MOI and LOI in alumina samples. To improve precision of analysis in cases where “as-received” results are not required, samples can be “air-equilibrated” prior to analysis. “Air-equilibration” can greatly affect MOI results and significantly alter LO
17、I results. The “air-equilibration” procedure and its effects are discussed in Annex A. Instrumental methods are also discussed. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For
18、undated references, the latest edition of the referenced document (including any amendments) applies. AS 2850, Chemical analysis Interlaboratory test programs For determining precision of analytical method(s) Guide to the planning and conduct 3 Principle The test portion of aluminium oxide is dried
19、at 300 C for 2 h and the loss of mass is determined by mass difference. The test portion is then ignited at 1 000 C for 2 h and the further loss of mass is determined. 4 Desiccants WARNING Because of the risk of explosion, do not attempt regeneration of magnesium perchlorate by oven drying. Magnesiu
20、m perchlorate and phosphorus pentoxide are hazardous and reference should be made to appropriate material safety information. One of the following desiccants shall be used: a) phosphorus pentoxide; b) activated alumina; c) magnesium perchlorate. ISO 806:2004(E) 2 ISO 2004 All rights reservedIf alumi
21、na is to be used as a desiccant it shall be freshly activated by heating for 12 h at (300 10) C and shall then be cooled for at least 4 h in the desiccator before use. The alumina shall be activated daily. 5 Apparatus 5.1 Vacuum desiccator (see Figure 1), containing an aluminium heat sink (5) with p
22、ositions for four crucibles and tray of desiccant. Figure 2 shows a suitable design for a heat sink. A metal tray of approximate dimensions 150 mm diameter and 30 mm depth and containing approximately 250 g of desiccant is suitable. The desiccator should be of such dimensions that the free circulati
23、on of air is not restricted (see Figure 1 for a suitable configuration). The desiccator lid inlet should also be fitted with a moisture trap containing a granular desiccant. 5.2 Platinum crucibles with lids, of 25 ml capacity and having approximate dimensions of 35 mm diameter and 40 mm depth. 5.3 E
24、lectric oven, capable of being controlled at (300 2) C, and fitted with mechanical air circulation. NOTE Ovens utilizing natural air convection are not likely to achieve the required temperature control. 5.4 Electric furnace, capable of being controlled at (1 000 10) C. 5.5 Balance, capable of weigh
25、ing to the nearest 0,000 1 g. 5.6 Thermogravimetric instrument, if required (see Clause 11). 6 Sample handling and preparation Aluminium oxide used for aluminium production is a mixture of phases, most of which are active and will rapidly absorb moisture from the atmosphere. Consequently, great care
26、 needs to be taken to minimize exposure to atmosphere. Seal samples in an airtight container immediately after collection. Leave space in the container to allow tumble mixing. Unless samples are prepared promptly and with a minimum of exposure to the laboratory atmosphere, inaccurate values for both
27、 moisture content and loss on ignition on an “as-received” basis will result. Tumble the sample bottle to mix the sample prior to analysis. Remove the test portion and seal immediately after the test portion has been taken from it. Do not use any sub-sampling or mixing technique that involves removi
28、ng all the bottle contents. 7 Procedure 7.1 Preparation of crucible and lid Prepare the crucible and lid as follows. a) Heat the crucible and lid in the furnace (5.4) at (1 000 10) C for 15 min. b) Remove the crucible and lid from the furnace, place in the desiccator (5.1) and allow to cool for 10 m
29、in. c) Weigh the crucible and lid and record the mass to the nearest 0,000 1 g (m 1 ). ISO 806:2004(E) ISO 2004 All rights reserved 37.2 Determination of loss of mass at 300 C (moisture content) Determine the loss of mass at 300 C as follows. a) Transfer a (5 0,5) g test portion from the test sample
30、 into the crucible, cover with the lid, weigh and record the total mass to the nearest 0,000 1 g (m 2 ). b) Immediately transfer the crucible and test portion into the oven (5.3). Remove the lid from the crucible and place in the desiccator or leave in the oven. Allow the oven to regain an operating
31、 temperature of (300 2) C and maintain this temperature for 120 min. c) Remove the crucible from the oven, place in the heat sink in the desiccator (5.1) and cover with the lid. Immediately evacuate the desiccator and allow to cool for 10 min. d) Slowly release the vacuum in the desiccator through a
32、 moisture trap without disturbing the test portion. Immediately weigh the crucible and lid and record the mass to the nearest 0,000 1 g (m 3 ). Minimize exposure to atmosphere, e.g. while the desiccator lid is off or while weighing, so as to prevent rapid moisture absorption of dried test portions.
33、7.3 Determination of loss of mass at 1 000 C (loss on ignition) Determine the loss of mass at 1 000 C as follows. a) Transfer the crucible and lid containing the dried test portion (see 7.2) to the furnace (5.4). Remove the lid from the crucible and place in the desiccator or leave in the furnace. A
34、llow the furnace to regain the operating temperature of (1 000 10) C. Maintain this temperature for 120 min. b) Remove the crucible from the furnace, place in the heat sink in the desiccator (5.1) and cover with the lid. Immediately evacuate the desiccator and allow to cool for 30 min. c) Slowly rel
35、ease the vacuum in the desiccator through a moisture trap without disturbing the test portion. Immediately weigh the crucible and lid and record the mass to the nearest 0,000 1 g (m 4 ). Minimize exposure to atmosphere, e.g. while the desiccator lid is off or while weighing, so as to prevent rapid m
36、oisture absorption of dried test portions. 8 Calculation Calculate the loss of mass at 300 C, w 300 , expressed as a percentage using Equation (1) 23 300 21 100 mm w mm = (1) where m 1is the mass, expressed in grams, of the empty crucible plus lid after conditioning (see 7.1), expressed in grams; m
37、2is the mass, expressed in grams, of the crucible, lid and test portion; m 3is the mass, expressed in grams, of the crucible, lid and dried test portion. The loss of mass on ignition, i.e. between 300 C and 1 000 C, may be reported either on an undried or on a dried basis (300 C) and shall be calcul
38、ated as a percentage using Equations (2) or (3). ISO 806:2004(E) 4 ISO 2004 All rights reservedCalculate the percent loss of mass on ignition (300 C to 1 000 C, denoted by 1000) on an undried basis, w 1000,u , using Equation (2): 34 1000,u 21 100 mm mm w = (2) where m 1 , m 2 , m 3are as defined in
39、Equation (1); m 4is the mass, expressed in grams, of the crucible, lid and ignited test portion. Calculate the percent loss of mass on ignition (300 C to 1 000 C, denoted by 1000) on a dried basis, w 1000,d , using Equation (3): 34 1000,d 31100mm w mm = (3) where m 1 , m 2 , m 3and m 4are as defined
40、 in Equations (1) and (2). Results shall be reported to the nearest 0,01 %. 9 Precision A planned trial of the method was carried out in accordance with AS 2850. Samples of five smelter grade aluminas were analysed on an “as-received” basis ranging from 0,5 % to 3,0 % moisture and 0,7 % to 0,9 % los
41、s of mass on ignition. Results were provided in quadruplicate by six laboratories. Loss of mass on ignition results were calculated on a dried basis. The within laboratory (r) and between laboratory (R) precision data (at 95 % confidence limits) calculated from the results are given in Table 1. Tabl
42、e 1 Precision data for loss of mass Values in percent Manual method Instrumental method Loss of mass Range of results Repeatability r Reproducibility R Repeatability r Reproducibility R 1 0,07 (5) 0,21 0,04 0,22 At 300 C (Moisture) W 1 0,05 0,12 0,04 0,20 At 1 000 C (Loss on ignition) All 0,06 0,12
43、0,03 0,07 10 Test report The test report shall include the following information: a) identification of the sample; b) reference to this International Standard (ISO 806:2004); ISO 806:2004(E) ISO 2004 All rights reserved 5c) the loss of mass at 300 C (moisture) and 1 000 C (loss on ignition), express
44、ed as a percentage by mass of the test portion, and a statement as to whether the sample was handled on an “as-received” or “air-equilibrated” basis; d) whether the loss of mass at 1 000 C (loss on ignition) percentage was calculated on a dried (300 C) or undried basis; e) the date on which the test
45、 was carried out; f) any unusual observations made during the course of the test which may have had an effect on the result. 11 Instrumental analysis The development of modern thermogravimetric instruments has allowed the determination of the moisture content and loss on ignition of smelter-grade al
46、umina to be automated. To ensure that the use of thermogravimetric instruments does not result in any loss of either analytical accuracy or precision, the following aspects of the determination have to be understood before they can be successfully applied. Parameters that are critical in the manual
47、determination, such as the time at 300 C and 1 000 C, the ability of an oven to be controlled at (300 2) C, a furnace that can be controlled at (1 000 10) C and a balance capable of weighing to the nearest 0,000 1 g and capable of weighing the total mass of crucible plus test portion, are just as si
48、gnificant for the determinations to be carried out in a thermogravimetric instrument. In addition, thermogravimetric instruments take time to reach 300 C. While reaching this temperature, the atmosphere in the furnace needs to be dry and it is necessary to purge the furnace with dry air. Even under
49、a dry atmosphere, the time to reach 300 C should not exceed 15 min and the time to increase from 300 C to 1 000 C should not exceed 20 min in order not to deviate significantly from the manual procedure. The use of thermogravimetric instruments is acceptable, provided that it can be demonstrated that the results so generated have an equivalent accuracy to those obtained by the manual method and have, for the particular material under test, a pre
