1、BS ISO20292:2009ICS 71.060.50; 71.100.10NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBRITISH STANDARDMaterials for theproduction of primaryaluminium Denserefractory bricks Determination ofcryolite resistanceThis British Standardwas published underthe authority of theStandard
2、s Policy andStrategy Committee on 30November 2009 BSI 2009ISBN 978 0 580 61736 2Amendments/corrigenda issued since publicationDate CommentsBS ISO 20292:2009National forewordThis British Standard is the UK implementation of ISO 20292:2009.The UK participation in its preparation was entrusted to Techn
3、icalCommittee CII/24, Raw materials for the aluminium industry.A list of organizations represented on this committee can be obtained onrequest to its secretary.This publication does not purport to include all the necessary provisionsof a contract. Users are responsible for its correct application.Co
4、mpliance with a British Standard cannot confer immunityfrom legal obligations.BS ISO 20292:2009Reference numberISO 20292:2009(E)ISO 2009INTERNATIONAL STANDARD ISO20292First edition2009-05-15Materials for the production of primary aluminium Dense refractory bricks Determination of cryolite resistance
5、 Matriaux pour la production de laluminium de premire fusion Briques rfractaires denses Dtermination de la rsistance de la cryolite BS ISO 20292:2009ISO 20292:2009(E) PDF disclaimer This PDF file may contain embedded typefaces. In accordance with Adobes licensing policy, this file may be printed or
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10、 + 41 22 749 09 47 E-mail copyrightiso.org Web www.iso.org Published in Switzerland ii ISO 2009 All rights reservedBS ISO 20292:2009ISO 20292:2009(E) ISO 2009 All rights reserved iiiContents Page Foreword iv 1 Scope 1 2 Principle1 3 Sampling.1 4 Reagents.1 5 Apparatus.1 6 Procedure.3 7 Precision sta
11、tement 5 8 Test report6 Bibliography7 BS ISO 20292:2009ISO 20292:2009(E) iv ISO 2009 All rights reservedForeword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is norma
12、lly 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 represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in th
13、e work. ISO collaborates 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 2. The main task of technical committees is to prepare
14、International Standards. Draft International Standards adopted by the technical committees 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
15、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 20292 was prepared by Technical Committee ISO/TC 226, Materials for the production of primary aluminium.BS ISO 20292:2009INTERNATIONAL STANDARD I
16、SO 20292:2009(E) ISO 2009 All rights reserved 1Materials for the production of primary aluminium Dense refractory bricks Determination of cryolite resistance 1 Scope This International Standard covers materials for the production of primary aluminium. This International Standard specifies a method f
17、or the determination of the resistance of dense refractory bricks to cryolite melt with excess sodium fluoride. 2 Principle A mixture of fine powders ( 100 m) of cryolite and sodium fluoride are allowed to react at 950 C in a furnace for 24 h in air, on a crucible-shaped test piece made of the dense
18、 refractory brick material to be tested. Reacted and/or infiltrated areas of brick material are calculated. Together with the calculation, a visual description of the reaction extent is recommended and photographs should also be used to illustrate the attack. 3 Sampling Take a number of different br
19、icks from within the batch to be tested. Take a minimum of two sample bricks to prepare test pieces. The test pieces are taken from different bricks. 4 Reagents 4.1 Cryolite (Na3AlF6) powder, with a minimum purity of 97 % mass fraction and a particle size 100 m. 4.2 Sodium fluoride (NaF) powder, wit
20、h a minimum purity of 99 % mass fraction and a particle size 100 m. IMPORTANT The electrolyte used in aluminium electrolysis will penetrate through the carbon block materials and then into the refractory. It is essential that this electrolyte penetration be stopped by reaction with the refractory. I
21、t is hence important to test the different refractory materials for resistance towards penetration. This test correlates well with penetration in industrial cells. 5 Apparatus 5.1 Diamond saw, with water cooling. 5.2 Core drilling apparatus, standard drilling machine with water cooling. BS ISO 20292
22、:2009ISO 20292:2009(E) 2 ISO 2009 All rights reserved5.3 Three drill pieces, to be mounted on the drilling machine: a) a 50 mm diamond core drill that gives a (57 1) mm hole; b) a 30 mm core drill; c) a 48 mm to 50 mm steel disk mounted on a stem, where pieces from a diamond core drill, that are 3 m
23、m high with the same radius of curvature as the disk, are glued on underneath (see Figure 1). 5.4 Furnace, capable of heating the test crucibles as required to (950 5) C. 5.5 Thermocouples, at least three, capable of measuring temperatures of 950 C. 5.6 Drying cabinets, capable of drying the test cr
24、ucibles as required at (110 5) C. 5.7 Photocopy machine. 5.8 Photocopy paper. 5.9 Balance, accurate to 0,01 g. SAFETY PRECAUTIONS During exposure, fluoride gas will be generated. The corrosive gasses will react and accumulate in the refractory lining in the furnace. The laboratory performing this te
25、st should preferably have a special (gastight) furnace for this test method. There is also a risk of the fluoride melt penetrating through the crucible and into the bottom lining of the furnace. The furnace should be placed in a well-ventilated room or be equipped with a spot extraction fan. Dimensi
26、ons in millimetres Key 1 steel base 2 pieces from a diamond core drill Figure 1 Underside of the steel disk for bottom smoothing BS ISO 20292:2009ISO 20292:2009(E) ISO 2009 All rights reserved 36 Procedure 6.1 Preparation of test crucibles Cut the sample bricks with the watercooled diamond saw (5.1)
27、 into test pieces with sides of length approximately 110 mm and height approximately 65 mm. Produce test crucibles with a borehole of diameter (57 1) mm and a depth of (40 1) mm in the middle of each test piece (see Figure 2). The borehole is produced using the core drilling apparatus (5.2) in the f
28、ollowing way. Use the 30 mm core drill (see 5.3) to make a hole in the middle of the test piece. Do not drill the hole all the way down to 40 mm. Pry the core loose. Then, apply the 50 mm core drill outside the first hole and remove the inside material. The disk with the mounted diamond pieces is us
29、ed to smooth the bottom and obtain the proper depth (see Figure 2). Use water cooling during all operations. Dimensions in millimetres Figure 2 Dimensions of test piece Cut the sample bricks with the diamond saw (5.1) into lids of suitable size and 10 mm thick to cover the borehole. Dry the test cru
30、cibles for at least 8 h at (110 5) C before the experiment. 6.2 Verification of suitability of furnace Verify the suitability of the furnace (5.4) to ensure that the test piece experiences a uniform temperature at (950 5) C as follows. Define and mark a sample location in the furnace. Place a test p
31、iece in the sample location. Place at least three thermocouples in the furnace, two positioned at opposite sides and one on the top of the test piece. Read the furnace temperatures from the thermocouples. At steady state (soaking), the temperature difference between the three thermocouples shall not
32、 exceed 8 C. To ensure completely identical test conditions, only one test piece is exposed at a time. 6.3 Test procedure Prepare a powder mixture consisting of 60 % mass fraction cryolite (4.1) and 40 % mass fraction sodium fluoride (4.2). Stir the mixture thoroughly with a glass rod for 1 min and
33、place 150 g of it in the borehole. Cover with the 10 mm lid (see third paragraph of 6.1) of the same material as the testing material. The lid should rest on the brick surface. Place the test crucibles in the furnace at the marked sample location (see 6.2). BS ISO 20292:2009ISO 20292:2009(E) 4 ISO 2
34、009 All rights reservedRaise the temperature of the furnace at a heating rate of 300 C/h up to 900 C. Then, continue heating from 900 C to 950 C at a heating rate of 50 C/h to prevent the furnace temperature overshooting. Keep the sample at (950 5) C for 24 h. The test is carried out in air. The flu
35、oride mixture will be liquid at 950 C. After completion of the 24 h stage at 950 C, switch off the furnace and allow it to cool. Remove the cooled crucible and saw through it diagonally (see Figure 3) in such a way that one cut plane includes the axis of the drilled hole. To ease the subsequent calc
36、ulation of the reacted and infiltrated area, it is recommended to draw a pencil line along the diagonal of the sample. The diamond-saw cut should be made along this line in such a way that the original dimension of the borehole is not changed during the cutting and remains as 57 mm 1 mm (see Figure
37、3). Examine this part of the test piece. Dimensions in millimetres Figure 3 Cutting of test piece 6.4 Evaluation 6.4.1 Calculation of reacted area Place the cut face of the test crucible in the photocopy machine (5.7) on a transparent plastic foil (to protect the machine). Take a paper photocopy of
38、the cut face. From the paper photocopy image, cut out the area corresponding to the dissolved area and weigh the paper piece (m1) to the nearest 0,01 g (see Figure 4). From the same paper, cut out 100 cm2and weigh to find the mass equivalent to 1 cm2(m2). BS ISO 20292:2009ISO 20292:2009(E) ISO 2009
39、All rights reserved 5Key 1 photocopy of tested brick after cutting 2 marking of original borehole dimensions 3 extracting the area for cryolite resistance determination (by cutting the paper with scissors) 4 reacted and infiltrated area used to determine cryolite resistance of tested brick Figure 4
40、Procedure to determine reacted area Calculate the dissolved area, A, in square centimetres (cm2), from the following equation: 12mAm= where A is the reacted area that has been dissolved, in square centimetres; m1is the mass, in grams, of the paper representing the dissolved area; m2is the mass per s
41、quare centimetre of the photocopy paper. Image-analysis equipment may also be used. In some cases, the electrolyte runs through the sample. This should only be given as a qualitative result. 6.4.2 Infiltrated area Usually the electrolyte reacts with the refractory. In some cases, an additional infil
42、tration without reaction is observed. A remark should be made if this is the case and the infiltrated area estimated. The same method as described in 6.4.1 can be used for calculating the infiltrated area. (Infiltration of a fluoride melt in refractory bricks is usually diffuse and not clearly defin
43、ed, which makes the calculations less accurate.) 7 Precision statement 7.1 Repeatability The results obtained with the same method on identical test pieces in the same test or measuring facility by the same operator using the same equipment within short intervals of time shall, in not less than 95 %
44、 of cases, differ by less than 0,7 cm2. BS ISO 20292:2009ISO 20292:2009(E) 6 ISO 2009 All rights reserved7.2 Reproducibility The results obtained with the same method on identical test pieces in different test or measurement facilities with different operators using different equipment shall, in not
45、 less than 95 % of cases, differ by less than 1,5 cm2. The precision is independent of the measured level of cryolite resistance in the range 2,0 cm2to 6,0 cm2. 8 Test report The test report shall include the following information: a) a reference to this International Standard; b) the place and date
46、 of testing; c) details necessary for the identification of the material tested (e.g. client, manufacturer, type, dimensions, etc.); d) number of crucible-shaped test pieces, dimensions of crucible and borehole; e) origin of the cryolite and sodium fluoride; f) type of furnace used for the experimen
47、t, dimensions of the furnace chamber; g) number of crucibles tested; h) test temperature; i) description of the crucible halves after the test, i.e. the appearance of the dissolved area and of the possibly infiltrated area; j) photocopies of the cut face; k) calculated areas of dissolved and possibl
48、y infiltrated areas, in square centimetres, to the nearest 0,1 cm. BS ISO 20292:2009ISO 20292:2009(E) ISO 2009 All rights reserved 7Bibliography 1 SILJAN, OLE-JACOB; SCHONING, CHRISTIAN and GRANDE, TOR: State-of-the-Art Alumino-Silicate Refractories for Al Electrolysis Cell, JOM, Vol. 54, No. 5, May
49、 2002, pp. 46-54; 63. BS ISO 20292:2009ISO 20292:2009(E) ICS 71.060.50; 71.100.10 Price based on 7 pages ISO 2009 All rights reserved BS ISO 20292:2009This page has been intentionally left blank BS ISO20292:2009BSI GroupHeadquarters 389Chiswick High Road,London, W4 4AL, UKTel +44 (0)20 8996 9001Fax +44 (0)20 8996 7
