1、 ISO 2012 Aluminium fluoride for industrial use Determination of trace elements Wavelength dispersive X-ray fluorescence spectrometric method using pressed powder tablets Fluorure daluminium usage industriel Dtermination dlments traces Mthode par spectromtrie de fluorescence des rayons X dispersion
2、de longueur donde utilisant des pastilles de poudre presse INTERNATIONAL STANDARD ISO 12926 First edition 2012-12-15 Reference number ISO 12926:2012(E) ISO 12926:2012(E)ii ISO 2012 All rights reserved COPYRIGHT PROTECTED DOCUMENT ISO 2012 All rights reserved. Unless otherwise specified, no part of t
3、his 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 at the address below or ISOs member body in the country of the requester. ISO copyright office Case postale 56 CH-1
4、211 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 ISO 12926:2012(E) ISO 2012 All rights reserved iii Contents Page Foreword iv Introduction v 1 Scope . 1 2 Normative references 1 3 Principle 1 4 Reagents and materials . 2 5 Ap
5、paratus . 2 6 Test procedure 3 6.1 Test specimen preparation . 3 6.2 Addition of binder method . 3 6.3 Backing method 4 6.4 X-ray fluorescence spectrometer application . 4 6.5 Monitor sample for correction of instrumental drift . 6 6.6 Analysis, calculation and expression of results . 6 7 Precision
6、. 6 7.1 General . 6 7.2 How to use Table 4 using sodium (Na) as an example . 7 7.3 How to use Table 4 using sulfur (S) as an example . 7 8 Test report . 8 Annex A (informative) Conversion table 9 Bibliography .10 ISO 12926:2012(E) Foreword ISO (the International Organization for Standardization) is
7、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 which a technical committee has been established has the right to be represent
8、ed 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 all matters of electrotechnical standardization. International Standards are dra
9、fted 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 circulated to the member bodies for voting. Publication as an International St
10、andard 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 responsible for identifying any or all such patent rights. ISO 12926 was prepared
11、 by Technical Committee ISO/TC 226, Materials for the production of primary aluminium.iv ISO 2012 All rights reserved ISO 12926:2012(E) Introduction Aluminium fluoride is used as an electrolyte additive to the aluminium smelting bath to regulate the acidity, or excess aluminium fluoride, level of th
12、e electrolyte. This use is critical in the operation of all electrolysis cells used for the production of aluminium. Aluminium fluoride is also used in the cast house as an additive to metal in crucibles in the Treatment of Aluminium in a Crucible process (TAC). ISO 2012 All rights reserved v Alumin
13、ium fluoride for industrial use Determination of trace elements Wavelength dispersive X-ray fluorescence spectrometric method using pressed powder tablets 1 Scope This International Standard describes an X-ray fluorescence spectrometric (XRF) method for the determination of aluminium fluoride (AlF 3
14、 ) from the content of fluorine and the content of trace elements in the test specimen. The method does not determine the oxygen content. The calibration reference materials are not specified in this method. The method is applicable to industrial-grade aluminium fluoride where the concentration rang
15、e for aluminium fluoride and each trace element is within the concentration range given in Table 1. The validity and precision of test results for concentrations outside these ranges has not been determined (see Note). Table 1 Concentration range for aluminium fluoride (from fluorine) and trace elem
16、ents Compound or element Symbol Concentration range mass % Aluminium fluoride AlF 3 86,5 to 95,75 Sodium Na 0,05 to 0,25 Silicon Si 0,001 to 0,14 Phosphorus P 0,001 to 0,02 Sulfur S 0,01 to 0,6 Calcium Ca 0,001 to 0,10 Iron Fe 0,005 to 0,05 NOTE The determination of fluorine has an uncertainty due t
17、o mineralogical variation among origins of aluminium fluoride. Batches from different origins with the same fluorine contents can give different intensities when determined by this method and pressed tablet preparation does not eliminate this problem. An AlF 3sample of unusual mineralogical origin s
18、hould be tested with an absolute method to verify that, when using this test method, the fluorine concentration range reported is valid. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited appl
19、ies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 1619, Cryolite, natural and artificial Preparation and storage of test samples 3 Principle A representative sample of aluminium fluoride is milled. A test portion is packed and pressed
20、on a powder tablet press to make the test tablets. The test tablets are analysed on an X-ray fluorescence spectrometer instrument that has been calibrated using a series of aluminium fluoride reference materials covering the required concentration range of the elements to be determined. INTERNATIONA
21、L ST ANDARD ISO 12926:2012(E) ISO 2012 All rights reserved 1 ISO 12926:2012(E) 4 Reagents and materials 4.1 Lithium tetraborate backing, analytical pure lithium tetraborate. 4.2 Acetone, analytical pure. 4.3 Aluminium tablet dish, of diameter suitable for the tablet press (5.3) and tapered to hold p
22、ressed pellets. 4.4 Mylar film, for keeping the test portion separate from press surfaces. 4.5 Binding agent, suitable for sample preparation. The following are some examples of materials that have been found satisfactory: polyethylene binder, PE-160, PE-190 mill and press additive, HMPA40 - Herzog
23、mill and press additive 1) XRF Multi-Mix RXR-250, Premier Lab Supply 2) Retsch - Licowax C micropowder binder (formerly known as Hoechst Wax or Hoechst LICO wax C Micropowder 3) wax, Clairiant Licowax PE-190 4) mixture, 9:1 of BASF styrene EMU 120 FD 5)to Hoechst Ceridust 9615A Wax. 4.6 Cleaning age
24、nt, if required. Dupont Vertrel XF (MS-782) 6)has been found suitable. 5 Apparatus 5.1 Wavelength dispersive X-ray fluorescence spectrometer, with vacuum path and equipped with crystals required as shown in Table 3. 1) HMPA40 - Herzog mill and press additive is the trade name of a product supplied b
25、y Hertzog Automation Corporation This information is given for the convenience of users of this document 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 the same results. 2) XRF Multi-Mix RXR-250 is the trade name o
26、f a product supplied by Premier Lab Supply. This information is given for the convenience of users of this document 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 the same results. 3) Licowax C micropowder (formerly
27、 Hoechst wax) is the trade name of a product supplied by Retsch, Socachim, Spectro. This information is given for the convenience of users of this document 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 the same res
28、ults. 4) Clairiant Licowax PE-190 is the trade name of a product supplied by Clariant Ltd (formerly Hoechst). This information is given for the convenience of users of this document and does not constitute an endorsement by ISO of the product named. Equivalent products may be used if they can be sh
29、own to lead to the same results. 5) BASF styrene EMU 120 FD is the trade name of a product supplied by BASF . This information is given for the convenience of users of this document and does not constitute an endorsement by ISO of the product named. Equivalent products may be used if they can be sho
30、wn to lead to the same results. 6) Dupont Vertrel XF (MS-782)is the trade name of a product supplied by Dupont This information is given for the convenience of users of this document and does not constitute an endorsement by ISO of the product named. Equivalent products may be used if they can be s
31、hown to lead to the same results.2 ISO 2012 All rights reserved ISO 12926:2012(E) 5.2 Vibratory disc mill, with tray, ring and puck made of non-contaminating material, tungsten- carbide and chrome steel have been found to be satisfactory. 5.3 Tablet press, capable of providing a 20 ton or up to 400
32、kN load for 10 s. 5.4 Mould with Mylar film, for forming tablets in press. 5.5 Desiccator, with a non-contaminating desiccant for storing calibration materials and monitor samples. 5.6 Balance, with precision 0,01 g. 5.7 Flat spatula. 6 Test procedure 6.1 Test specimen preparation Two methods of sam
33、ple preparation are described: the addition of binder method and the backing method. Either method may be used. NOTE The addition of binder method is most used but the preparation of the precision statement showed that several different methods of sample preparation gave good and sufficient within-l
34、aboratory repeatability. See ISO 1619 for guidance. 6.2 Addition of binder method 6.2.1 Dry the sample to constant mass at (110 to 120) C. 6.2.2 Take a test portion and weigh it, taking care to always use the same mass as for the calibration reference material. A typical test portion is 10,0 g. 6.2.
35、3 Mix the test portion with binding agent (see the list of examples in 4.5) before grinding in the disc mill (5.2), taking care to always use the same mass and proportion of sample and binding agent as for the calibration reference materials. Some examples of binders in use are given in Table 2. NOT
36、E The binding agent can decrease the level of segregation in the sample and make it easier to remove the tablet from the grinding vessel. Table 2 Some examples of test portion size and binding agents (4.5) in the addition method Test portion g Binder addition a 10,0 8 pills Hoechst PE-190 amounting
37、to 1,0 g 5,0 + 4,0 ml Dupont Vertrel XF Cleaning Agent (MS-782) + 0,5 g binder tablet Premier Lab Supply (XRF Multi-Mix RXR-250) 10,0 2,5 g of 9:1 BASF styrene EMU 120 FD: Hoechst Ceridust 9615A Wax 4,0 2,0 g binder (Lico wax C Micropowder) aThese materials can be replaced with products with similar
38、 properties 6.2.4 Mill (5.2) the sample until all particles are below 63 micrometer fineness. NOTE 1 Examples of milling t imes are 10 s to 10 min, typical is (1 to 4) min. Short milling times give larger spread in within-laboratory precision. The particle size should be determined by using a suitab
39、le sieving technique. ISO 2012 All rights reserved 3 ISO 12926:2012(E) NOTE 2 Results are particle size dependent, and erroneous data will be collected if analytical samples contain particles varying significantly in size that cause different beam penetration depth and a different surface roughness
40、from those in the calibration reference samples. 6.3 Backing method 6.3.1 Pack with 2 mm of lithium tetraborate backing (4.1) in the aluminium tablet dish (4.3) or directly in the die, on fresh Mylar film (4.4). 6.3.2 Transfer a sufficient test portion to produce a cylindrical tablet 4 mm to 7 mm th
41、ick. When using an aluminium tablet dish, make a pile of maximum height above the lip of the dish, and hand pack with a flat spatula (5.7) until the ground mix is level with the lip of the dish. 6.3.3 Place fresh Mylar film on top so the press does not touch the tablet surface. 6.3.4 Press to achiev
42、e a stable tablet. Use the same time for pressure, pressure load and pressure time for the test portions as for the calibration reference material, i.e. use the same pressure profile for the calibration reference materials and test samples. Example of pressure and time are 20 ton to 40 ton for (10 t
43、o 30) s, typical is 25 ton and 20 s with a 40 mm diameter tablet. Release the pressure slowly. 6.3.5 Remove the tablet from the die and inspect the tablet surface to ensure that it is smooth and free from cracks. Mark the pellet for identification. NOTE Aluminium fluoride tablets can fracture follow
44、ing removal from the press. This problem is described in the literature as a problem of slight deformation of the die or sample cup under high pressure. See Reference3: V. Buhrke et al., Preparation of specimen for X-ray fluorescence and X-ray diffraction analysis, Wiley-VCH, 1998, page 41. Laborato
45、ries report that a certain level of experience with this sample preparation is needed to reduce this problem of fracture of tablets. 6.4 X-ray fluorescence spectrometer application 6.4.1 Instrumental conditions Follow the control setting and operation instructions of the spectrometer (5.1) manufactu
46、rer including monitoring and calibrating angles and monitoring and correcting for X-ray tube intensity. Suggested conditions of measurement are given in Table 3. All measurements shall be made under vacuum. The K analytical lines are preferred. Use spectral lines overlap correction if required; also
47、 correct for background; several lines are recommended in the table for this. NOTE 1 The preparation of the precision statement showed that several choices of measurement lines gave good and sufficient within-laboratory repeatability. For this reason, these lines are included. NOTE 2 Regarding count
48、ing times in Table 3, this gives some guidance but if the XRF is less sensitive than typical these times may be short.4 ISO 2012 All rights reserved ISO 12926:2012(E) Table 3 Measurement lines and suggested conditions of measurement Element Crystal Angle Counter Time Collima- tor Voltage Current Bac
49、k- ground 2 s kV mA 2 F XS-55 K 60 0,46 27 111 F AXO6 Na XS-55 K 30 to 100 0,46 27 111 Na TlAP 55,1 Flow 30 to 100 0,6 40 60 2 2 Na PX1 30 to 100 Na AXO6 30 to 100 Si PET K 20 to 30 0,46 27 111 Si PET a 109,215 Flow 20 to 30 0,6 40 60 Si InSb 7, 52 Flow 20 to 30 0,6 40 60 Si InSb 144,95 Flow 20 to 30 0,6 40 60 142,85; 147,05 Si PX1 P PET K 20 0,46 27 111 P PET a 89,56 Flow 20 0,6 40 60 P Ge(III) 141,03 t
