1、 g49g50g3g38g50g51g60g44g49g42g3g58g44g55g43g50g56g55g3g37g54g44g3g51g40g53g48g44g54g54g44g50g49g3g40g59g38g40g51g55g3g36g54g3g51g40g53g48g44g55g55g40g39g3g37g60g3g38g50g51g60g53g44g42g43g55g3g47g36g58Determination of particles passing a 20 micrometre aperture sieveICS 71.100.10Aluminium oxide used
2、for the production of aluminium BRITISH STANDARDBS ISO 23202:2006BS ISO 23202:2006This British Standard was published under the authority of the Standards Policy and Strategy Committee on 30 March 2007 BSI 2007ISBN 978 0 580 50460 0Amendments issued since publicationAmd. No. Date Commentscontract. U
3、sers are responsible for its correct application.Compliance with a British Standard cannot confer immunity from legal obligations. National forewordThis British Standard was published by BSI. It is the UK implementation of ISO 23202:2006.The UK participation in its preparation was entrusted to Techn
4、ical Committee CII/24, Raw materials for the aluminium industry.A list of organizations represented on CII/24 can be obtained on request to its secretary.This publication does not purport to include all the necessary provisions of a Reference numberISO 23202:2006(E)INTERNATIONAL STANDARD ISO23202Fir
5、st edition2006-06-01Aluminium oxide used for the production of aluminium Determination of particles passing a 20 micrometre aperture sieve Oxyde daluminium utilis pour la production de laluminium Dtermination de la finesse des particules: mesure du passant 20 micromtres BS ISO 23202:2006ii iiiConten
6、ts Page Foreword iv Introduction v 1 Scope . 1 2 Normative references . 1 3 Principle. 1 4 Safety . 1 5 Reagents 1 6 Apparatus 2 7 Sampling and sample preparation 3 8 Procedure 3 9 Calculation and expression of results 5 10 Precision 5 11 Quality control. 5 12 Test report . 6 Annex A (informative) R
7、esults of test programme . 7 Annex B (normative) Determination of effective aperture of the test sieve. 8 Bibliography . 10 BS ISO 23202:2006iv Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of pr
8、eparing 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 represented on that committee. International organizations, governmental and non-governmental, i
9、n 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 drafted in accordance with the rules given in the ISO/IEC Directives, Part 2. The main tas
10、k 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 Standard requires approval by at least 75 % of the member bodies casting a vote. Attentio
11、n 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 23202 was prepared by Technical Committee ISO/TC 226, Materials for the production of primary aluminium.
12、BS ISO 23202:2006vIntroduction This International Standard is based on Australian method, AS 2879.2-2003, Alumina Determination of particles passing a 20 micrometre aperture sieve. The Minus 20 Micron reference material ASCRM 026 was released in December 2003 by SAI Global, along with a Technical Re
13、port on its preparation (TR 2.26-2003, Certified reference materials Alumina Preparation and certification of ASCRM 026). These are available from SAI through their website: http:/.au/ BS ISO 23202:2006blank1Aluminium oxide used for the production of aluminium Determination of particles passing a 20
14、 micrometre aperture sieve 1 Scope This International Standard sets out a wet-sieving procedure for the determination of the percentage by mass of particles of smelter-grade alumina passing a 20 m aperture sieve. This procedure is applicable for aluminas with a 20 m content up to 4 %. 2 Normative re
15、ferences The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 802:1976, Aluminium oxide primarily
16、used for the production of aluminium Preparation and storage of test samples ISO 806:2004, Aluminium oxide primarily used for the production of aluminium Determination of loss of mass at 300 C and 1 000 C ISO 3310-3, Test sieves Technical requirements and testing Part 3: Test sieves of electroformed
17、 sheets 3 Principle A test sample of alumina is sieved on a 20 m electroformed sieve, using acetone, and the retained material is determined gravimetrically after drying at 300 C. 4 Safety Chemicals used may be hazardous or toxic and reference should be made to the appropriate Material Safety Data S
18、heets. CAUTION ACETONE PRESENTS A FLAMMABILITY RISK AND SHOULD BE USED IN A SUITABLE EXTRACTION HOOD. 5 Reagents 5.1 Acetone, analytical reagent grade. 5.2 Desiccant. Phosphorous pentoxide, activated alumina and molecular sieves have been found to be suitable. Silica gel is not a suitable desiccant.
19、 BS ISO 23202:20062 WARNING PHOSPHOROUS PENTOXIDE IS A HAZARDOUS MATERIAL AND REFERENCE SHOULD BE MADE TO THE APPROPRIATE MATERIAL SAFETY DATA SHEET. 5.3 Ethanol or methanol, technical grade. 6 Apparatus Ordinary laboratory equipment and the following. 6.1 Test sieve, consisting of a frame, nominall
20、y of diameter 75 mm to 150 mm, with an electroformed 20 m aperture mesh constructed and tested in accordance with ISO 3310-3. The aperture shape shall be round and the sieving medium shall be supported by a suitable grid to provide adequate strength. The construction materials shall be such that the
21、 sieve is resistant to chemical corrosion and no physical damage shall occur as a result of heating to 110 C. The mesh shall be attached to the frame of the sieve such that particles cannot lodge in any part of the joining seam. NOTE Two suitable mesh sizes are commonly available, 317# and 570#. The
22、 open area of the mesh is approximately 17 % for the 570#, and 3,5 % for the 317#. Thus, the 570# sieve is more efficient but more fragile than the 317# sieve. 6.2 Sieve brush, which is acetone-compatible, of high quality with an unpainted handle and soft bristles. Any paint on the brush shall be re
23、moved. NOTE 1 Westart Akrilik Filbert #6 or #8 brushes have been found suitable. This information is given for the convenience of users of this International Standard and does not constitute an endorsement by ISO of the product named. Equivalent products may be used if they can be shown to lead to t
24、he same results. NOTE 2 A stiff-bristled brush (e.g. hogs bristle) is not suitable, as it may bias the analysis high and may also damage the sieve mesh. NOTE 3 A dark-bristled brush is useful, as any alumina particles adhering to the bristles are easily seen. 6.3 Ovens, fitted with mechanical air ci
25、rculation and capable of being controlled at (300 10) C. 6.4 Vacuum desiccator, containing an aluminium heat sink, in accordance with ISO 806, and a tray containing desiccant. A tray containing approximately 250 g of desiccant is suitable. 6.5 Platinum crucibles, of 25 ml capacity and approximate di
26、mensions of 35 mm diameter and 40 mm depth and fitted with lids. Two crucible and lid sets are required for each determination. The crucible and lid sets shall be conditioned by placing in an oven maintained at (300 10) C for 30 min, then cooled and stored in the heat sink in the desiccator. 6.6 Was
27、h bottle, made of polyethylene and filled with reagent-grade acetone. 6.7 Ultrasonic bath. 6.8 Sample scoop, made of stainless steel or brass with a handle. Nominally this scoop shall take up to 0,5 g of alumina when loaded. (See Figure 1.) Dimensions in millimetres BS ISO 23202:20063aWall thickness
28、 (nominal). Figure 1 Typical sampling scoop 7 Sampling and sample preparation A 50 g test sample shall be prepared from the laboratory sample as specified in ISO 802, taking particular care to avoid loss of fine particles through dusting. The test sample shall be mixed well by manual or mechanical t
29、umbling in a sealed container that is not more than 75 % full. After tumbling, let the container rest to allow fines to settle. Each test portion shall be extracted with the sample scoop (6.8), taking a number of grabs to make up the required mass. Manual tumbling shall be repeated between extractio
30、n of test portions. A flat-bladed spatula or vibrating spatula should not be used, as segregation may occur. 8 Procedure 8.1 Check the sieve The sieve shall be checked to ensure that the mesh is not ruptured and that there is not excessive aperture blinding. When holding the sieve up to a light sour
31、ce, areas of blinding are visible as being darker in appearance. If more than 30 % of the sieve mesh is blinded, the sieve shall be cleaned as specified in 8.2. Larger ruptures in the sieve may be seen by visual inspection. To see smaller ruptures, magnification is required. Inspection using a stere
32、o-microscope is recommended; scan the entire mesh area and the edges to check for ruptures. NOTE Ruptures can be successfully repaired using silver solder. When a repair is carried out, check the repaired area under magnification to ensure that the rupture is covered and that the solder is bonded to
33、 the mesh. 8.2 Cleaning sieve The procedure shall be as follows. a) Submerge the sieve in a beaker containing 50 % ethanol or methanol in water. The beaker should be of sufficient diameter to hold the sieve on its side. b) Place the beaker in an ultrasonic bath and sonicate for 10 min. c) Remove the
34、 sieve and inspect for aperture blinding. d) Repeat sonication if blinding is still greater than 30 %. NOTE The sieve is placed on its side during sonication to prevent damage. BS ISO 23202:20064 8.3 Test procedure The procedure shall be as follows: a) Using the sample scoop (6.8), transfer a (2 0,1
35、) g test portion of the test sample into a tared weighing vessel. Record the mass to the nearest 0,000 1 g (m1) and transfer to a clean 20 m test sieve (6.1). b) Weigh two conditioned platinum crucible and lid sets (A and B), and record their masses (m2and m3, respectively). Using the sample scoop,
36、transfer another (2 0,1) g test portion to crucible A. Reweigh crucible set A and record the mass (m4). Record all masses to the nearest 0,000 1 g. Crucible set A holds the test portion used for moisture correction and is retained in a desiccator until Step i). Crucible set B is used to dry the siev
37、ed test portion. Both test portions should be weighed out at the same time. NOTE 1 The crucible and lid set conditioning procedure is given in 6.5. c) Place the sieve with the test portion in a fume cupboard. d) Wet the test portion in the sieve with approximately 50 ml of acetone poured from the wa
38、sh bottle (6.6), and then sieve the material by flooding with a jet of acetone delivered from the wash bottle whilst brushing (see 6.2). Wash any alumina that collects on the inside frame wall of the sieve onto the sieve mesh with acetone. Collect the spent acetone and dispose of or recycle in accor
39、dance with environmental good practice. Pressure on the brush should be just sufficient to cause slight bending of the bristles. The purpose of brushing is to suspend the fines in the acetone, to enable them to be washed through the sieve. NOTE 2 Take care not to lose any sample as the jet of aceton
40、e impinges on the sieve. Splashing may result in a loss of sample. e) Continue sieving for 10 min in a manner such that all of the alumina and all parts of the sieve mesh receive equal washing and brushing. f) Remove any alumina from the brush by pressing the brush firmly against the inside wall of
41、the sieve, simultaneously washing with a jet of acetone and rotating the brush. The total volume of acetone passing through the sieve in a single determination should be at least 400 ml. If it is less, not all the fines may be washed through the sieve. A low volume of acetone indicates that the siev
42、e is blinded due to inadequate cleaning and inspection (see 8.2) or the sieve may be overloaded with fines. In the case of the latter, clean the sieve (see 8.2) and repeat the analysis using nominally a 1 g sample. g) Quantitatively transfer the contents of the sieve to crucible B and wash any adher
43、ing alumina from the sieve into the crucible with a jet of acetone. NOTE 3 This step is conveniently accomplished using a funnel held on a retort stand over the receiving crucible. h) Carefully evaporate to dryness in a fume hood, avoiding sample loss. NOTE 4 An infrared lamp is suitable for evapora
44、ting acetone. i) Heat crucible sets A and B in the oven (6.3) maintained at (300 10) C for 2 h. WARNING DO NOT TRANSFER THE CRUCIBLES TO THE OVEN UNTIL THE ACETONE HAS EVAPORATED COMPLETELY. j) Remove the crucible sets from the oven, place in the heat sink in the desiccator (ensuring the lids cover
45、the crucible) and immediately evacuate the desiccator. Allow to cool. BS ISO 23202:20065k) Reweigh crucible sets A and B and record the masses (m5and m6, respectively), to the nearest 0,000 1 g. 9 Calculation and expression of results The mass fraction, in percent of material passing the 20 m apertu
46、re sieve (w20), shall be calculated from the following equation and expressed to one decimal place on an as-received basis: ()( )()63 4220152100100mm mmwmmm=where w20 is the mass fraction, in percent of the material passing the 20 m aperture sieve; m6 is the mass of crucible set B and the +20 m frac
47、tion of the test portion after heating at 300 C, in grams; m3 is the mass of empty crucible set B, in grams; m4 is the mass of crucible set A and sample prior to heating at 300 C, in grams; m2 is the mass of empty crucible set A, in grams; m1 is the mass of sample taken for the sieve test, in grams;
48、 m5 is the mass of crucible set A and sample after heating at 300 C, in grams. 10 Precision A test programme of the method in this International Standard was carried out according to AS 2850. From the results of this programme, a within-laboratory repeatability (r) and between-laboratory reproducibi
49、lity (R) at the 95 % confidence level as given in Table 1 should be achieved. NOTE The results of the test programme are given in Annex A. Table 1 Precision data for 20 m analysis Mass fraction, % (absolute) Repeatability (r) Reproducibility (R) 0,24 0,47 11 Quality control A reference sample, such as ASCRM 026 1), should be run with each batch of samples. Particular care should be taken in the tumble mixing and sampling procedures (see Clause 7) to ma
