1、BRITISH STANDARD BS 1902-9.2: 1987 Incorporating Amendment No. 1 Methods of testing Refractory materials Part 9: Chemical analysis by instrumental methods Section 9.2 Analysis of silica refractories by X-ray fluorescence UDC 666.762.2:543.42.062BS1902-9.2:1987 This British Standard, having been prep
2、ared under the direction of the Refractory Products Standards Committee, was published under the authority of the Board of BSI and comes into effect on 31March1987 BSI 06-1999 The following BSI references relate to the work on this standard: Committee reference RPM/1 Draft for comment 85/39184 DC IS
3、BN 0 580 15534 X Committees responsible for this British Standard The preparation of this British Standard was entrusted by the Refractory Products Standards Committee (RPM/-) to Technical Committee RPM/1, upon which the following bodies were represented: British Ceramic Research Ltd. British Steel
4、Industry Electricity Supply Industry in England and Wales Engineering Equipment and Materials Users Association Refractories Association of Great Britain Refractory Contractors Association Society of Glass Technology Amendments issued since publication Amd. No. Date of issue Comments 6576 April 1991
5、 Indicated by a sideline in the marginBS1902-9.2:1987 BSI 06-1999 i Contents Page Committees responsible Inside front cover Foreword ii 1 Scope 1 2 Principle 1 3 Preparation of the analysis sample 1 4 Reagents 1 5 Apparatus 2 6 Preparation of beads 3 7 Presentation of beads 4 8 XRF spectrometer 4 9
6、Ratio standard beads and calibration 5 10 Analysis 6 11 Correction for tungsten carbide contamination and loss on ignition 6 12 Reporting of results 7 13 Test report 7 Appendix A Tungsten carbide corrections with cobalt or nickel bonds 8 Appendix B Recommended composition of ratio standard beads 8 A
7、ppendix C Analysis of silica sands used in glass manufacturing 9 Figure 1 Combined vessel for top surface presentation 7 Table 1 Ranges of content 1 Table 2 Reproducibility of spectrometer 4 Table 3 Maximum allowable detection limits 5 Table 4 Recommended composition of ratio standard bead 8 Table 5
8、 Recommended composition of second ratio standard bead 9 Publications referred to Inside back coverBS1902-9.2:1987 ii BSI 06-1999 Foreword This Section of BS 1902-9 has been prepared under the direction of the Refractory Products Standards Committee. It is one of a series of Sections covering chemic
9、al analysis by instrumental methods, and describes the X-ray fluorescence (XRF) technique. The method is based on the fused, cast bead technique which is the current accurate industrial method for the preparation of oxide materials for XRF in the United Kingdom and much of Europe. The flux used is o
10、f low melting point, which greatly assists mixing and dissolution of the samples. The flux has successfully been applied to the analysis of silica/alumina materials from sand through clays, feldspars, etc. to pure alumina materials, and is also suitable for a whole range of other materials including
11、 zircon, steatite, glazes, frits, fluxes, glasses, fluorspar and gypsum. The standard was amended in1991 to include an appendix covering the analysis of silica sands used in glass manufacturing. A British Standard does not purport to include all the necessary provisions of a contract. Users of Briti
12、sh Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages1 to 12, an inside back cover and a back cover
13、. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover.BS1902-9.2:1987 BSI 06-1999 1 1 Scope This Section of BS 1902-9 describes a method for analysing silica refractories using X-ray flu
14、orescence. The method is intended for materials containing more than92% of silica (SiO 2 ) on the ignited basis. The ranges of content of constituents are given inTable 1 except for those used in glass manufacture which are given inAppendix C. Appendix C gives modifications to this method which are
15、required where it is to be used for the analysis of silica sands used in glass manufacture. Table 1 Ranges of content NOTEThe titles of the publications referred to in this standard are listed on the inside back cover. 2 Principle The powdered sample is fused with a flux to destroy its mineralogical
16、 and particulate composition. The resultant melt is cast into a glass bead which is introduced into an X-ray fluorescence spectrometer. The intensities of the fluorescent X-rays of the required elements in the bead are measured and the chemical composition of the sample is analysed by reference to p
17、reviously determined calibration graphs or equations. 3 Preparation of the analysis sample The sample shall be finely ground (the bulk to be finer than1254m equivalent spherical diameter), either by using a suitable mechanical device and appropriate grinding times, or by hand. The grinding media sha
18、ll be agate, boron carbide or tungsten carbide. If the latter is used, the contamination shall be monitored and the appropriate corrections applied to the analysis and loss on ignition figure (see clause11). 4 Reagents 4.1 Flux 1) . The flux shall be a mixture of one part by mass lithium tetraborate
19、 (Li 2 B 4 O 7 ) to four parts by mass lithium metaborate (LiBO 2 ), the ratio being of the dry fluxes. It shall be of an analytical quality. In practice the flux will contain a certain amount of moisture. This shall be corrected for in one of two ways. a) Ignite the entire quantity of flux required
20、 overnight at700C immediately before it is used for analysis and then store in a desiccator. b) Carry out duplicate losses on ignition on1g portions of the well mixed contents of each kilogram of flux used. The ignition is either at700C for1h or at1200C for10min. Keep the flux tightly sealed except
21、when in use. The loss on ignition, expressed as a percentage L, is then used to calculate a factor f (see equation1) which is in turn used to calculate the mass of the unignited flux needed to produce the required mass of flux on the ignited basis (f required mass of ignited flux=required mass of un
22、ignited flux). Carry out this loss on ignition weekly, or for each kilogram of flux used, whichever is the more frequent. Re-check calibrations when batches of flux are changed. 4.2 Oxides or carbonates for glass beads. The reagents used to prepare the standard beads for cations shall be pure oxides
23、 or carbonates of at least99.95% purity (excluding moisture or CO 2 ) for minor constituents and of at least99.99% purity for silica. Oxide Range % Silica (SiO 2 ) Titanium oxide (TiO 2 ) Alumina (Al 2 O 3 ) Iron (III) oxide (Fe 2 O 3 ) Calcium oxide (CaO) Magnesium oxide (MgO) Sodium oxide (Na 2 O)
24、 Potassium oxide (K 2 O) Tungsten oxide (WO 3 ) Cobalt oxide a(Co 3 O 4 ) Nickel oxide a(NiO) 92 to 100 0.01 to 0.5 0.01 to 2.0 0.01 to 2.0 0.01 to 3.0 0.03 to 0.5 0.05 to 0.5 0.01 to 2.0 0.02 to 1.0 0.01 to 1.0 0.01 to 1.0 NOTEOther elements may be added as necessary. a These ranges are for the ana
25、lysis of the binder in the tungsten carbide mortar, which may be either cobalt or nickel. The appropriate analysis should be carried out. 1) For information on the availability of suitable premixed fluxes, apply to the Enquiry Section, BSI, Linford Wood, Milton Keynes MK146LE, enclosing a stamped ad
26、dressed envelope for reply. (1) where L is the loss on ignition (in%). f 100 100 L - =BS1902-9.2:1987 2 BSI 06-1999 In order to obtain the reagents in a known stoichiometry in terms of content they shall be treated before use as follows. a) Silica, alumina and magnesium oxide. Determine the loss on
27、ignition as follows. Ignite the material at1200C and keep it at this temperature for30min before use. Cool in a desiccator to room temperature. After allowing for this loss weigh the appropriate amount of the unignited material to prepare the standard bead. b) Titanium oxide. Ignite the material at1
28、000C and keep it at this temperature for30min before use. Cool in a desiccator to room temperature. c) Iron (III) oxide. Ignite the material at700C and keep it at this temperature for30min before use. Cool in a desiccator to room temperature. d) Calcium carbonate, tungsten oxide, potassium carbonate
29、 and sodium carbonate. Dry at220C to constant mass before use. Cool in a desiccator to room temperature. NOTE 1A 2h treatment is usually sufficient for drying. NOTE 2Tungsten carbide (WC) will be introduced as a contaminant if this media is used for grinding. Laboratories using tungsten carbide for
30、sample grinding should calibrate for WO 3 in order to monitor its presence in samples, and hence correct the analysis and the loss on ignition for WC contamination (see clause11). Unlike the chemical analysis procedure, X-ray fluorescence determinations are not subject to any significant interferenc
31、e due to tungsten and furthermore the contaminant tungsten can be easily monitored. 5 Apparatus 5.1 Vessels used for the fusion of samples with flux, with the exception of the lids(5.5) shall be constructed from a platinum alloy that is not wetted by the melt. The casting moulds shall be made from a
32、ny suitable material not wetted by the melts, which does not contaminate the sample or cause reduction. NOTEA mould consisting of95% platinum and5% gold is suitable. 5.2 Fusion dishes of sufficient capacity to hold the quantity of unfused flux and sample required by the size of the casting mould. NO
33、TEFor a 35 mm diameter bead where1.5g sample and7.5g flux are used, a fusion dish of50mL capacity is suitable. 5.3 Casting moulds 2)designed to give a circular bead of a diameter within the range25mm to40mm and of thickness to exceed the critical depth for the element lines used in analysis. The sid
34、es shall be set at a suitable angle to the vertical to ensure that the beads are readily released. If the top surface of the bead is to be used for analysis, there shall be a horizontal rim to the casting mould and the mass of melt shall be sufficient to fill the mould and give a reproducible curved
35、 top surface. NOTE 1Calibration and analysis are carried out using the same pattern and size of casting mould throughout. NOTE 2Once a size and type of mould has been selected, it should be used throughout; if it is changed, re-calibration is required. 5.4 Fusion moulds 2) NOTE 1As an alternative me
36、thod to fusion in a dish followed by casting into a mould, it is permissible to use a combined vessel which functions both as a fusion dish and a casting mould (seeFigure 1). The volume of the dish shall be sufficient to hold the unfused sample and flux required to fill the mould part of the vessel
37、when fused. The mould part of the vessel shall comply with5.2. In addition, if it is intended that the top surface of the bead produced by the vessel is to be used for presentation to the X-ray fluorescence spectrometer, a horizontal rim shall be interposed between the top of the mould and the sides
38、 of the dish. NOTE 2If the rim is not present concave top surfaces will be produced on the beads, which are not conducive to accurate analysis. NOTE 3Once a size and type of mould has been selected it should be used throughout; if it is changed, re-calibration is required. 5.5 Lids for dishes and fu
39、sion moulds large enough to completely cover the dishes; they are not required to be of a non-wetted alloy of platinum. NOTEPlatinum itself is suitable. 5.6 Heat reservoir for casting mould (optional) NOTE 1A heat reservoir is usually required when using moulds of small sizes, so that the mould does
40、 not cool too rapidly when removed from the furnace. NOTE 2A small piece of flat refractory material is suitable, e.g.a piece of sillimanite batt with approximate dimensions10mm thick by50mm square. 5.7 Air jet (optional) NOTE 1An air jet is usually required to free the melt from the dish and to coo
41、l the former rapidiy. This can be any device whereby a narrow jet of air can be directed to the centre of the base of the casting dish. NOTE 2A convenient way of doing this is to use the base of a bunsen burner without the barrel. 2) For information on the availability of suitable casting and fusion
42、 moulds, apply to the Enquiry Section, BSI, Linford Wood, Milton Keynes MK146LE, enclosing a stamped addressed envelope for reply.BS1902-9.2:1987 BSI 06-1999 3 6 Preparation of beads 6.1 Loss on ignition NOTE 1The mass of sample resulting after the loss on ignition determination should be sufficient
43、 to produce an adequate mass of sample for the fusion procedure. In practice the mass required will be1g to2g, which should be weighed to 0.0005g. Dry the ground sample at1105C for at least4h, or to constant mass. Store the samples over a drying agent in desiccators while cooling. NOTE 2Silica gel,
44、calcium chloride or any similar desiccant is suitable. Weigh 1.000g into a suitable platinum alloy vessel (see5.2 and5.4) of known mass. Almost completely cover the vessel with a lid, and then either place the vessel in a muffle furnace and slowly raise the temperature to1025 25C; or start the ignit
45、ion over a low flame, taking care to ensure oxidizing conditions, and slowly increase the temperature to a dull red heat over a period of20min, then transfer the vessel to a furnace at1025 25C. NOTE 3A suitably programmed tunnel kiln may be used to carry out the slow increase in temperature and subs
46、equent ignition. Ignite to constant mass at this temperature. NOTE 4Ignition for 30min is usually sufficient. Remove the vessel from the furnace, completely cover with the lid, cool to room temperature in a desiccator and reweigh immediately. Correct the recorded loss on ignition figure for the effe
47、ct of any tungsten carbide introduced into the sample being oxidized to WO 3(see clause11). 6.2 Fusion of samples and casting of beads NOTEAt several of the stages, a choice of procedures is given. Once a choice has been made, the procedure should be adhered to throughout, unless a re-calibration is
48、 carried out. 6.2.1 General. Before fusing the samples and casting the beads, the following requirements shall be satisfied. a) Duplicate or single beads may be prepared; the method used shall be stated in the test report (see clause13). NOTEDuplicate beads are preferable to single beads. However, i
49、f all the elements inTable 1 are determined, an analytical total will be achieved which acts as a check on the accuracy of the analysis. b) The total mass of sample and flux shall be chosen for the particular casting mould type used, and this mass shall always be the same. c) The ratio by mass of the flux to the sample shall be5:1. d) The melts produced shall be homogeneous. e) There shall be no measurable loss of any component from the sample during fusion, e.g.loss of Fe 2 O 3by reduction or loss of alkalis due to evaporat
