1、BRITISH STANDARD BS 6200-3.1.5: 1985 ISO 4139:1979 Sampling and analysis of iron, steel and other ferrous metals Part 3: Methods of analysis Section 3.1 Determination of aluminium Subsection 3.1.5 Ferrosilicon: atomic absorption spectrometric method ISO title: Ferrosilicon Determination of aluminium
2、 content Flame atomic absorption spectrometric method UDC 669.1:543.422.062:546.62BS 6200-3.1.5:1985 This British Standard, having been prepared under the directionof the Iron and Steel Standards Committee, was published under the authority of the Board of BSI and comes intoeffect on 28February1985
3、BSI 09-1999 The following BSI references relate to the work on this standard: Committee reference ISM/18 Draft for comment78/70864 DC ISBN 0 580 14262 0 National foreword This Subsection of BS6200 has been prepared under the direction of the Iron and Steel Standards Committee. It is identical with I
4、SO4139:1979 “Ferrosilicon Determination of aluminium content Flame atomic absorption spectrometric method” published by the International Organization for Standardization (ISO). Terminology and conventions. The text of the International Standard has been approved as suitable for publication as a Bri
5、tish Standard without deviation. Some terminology and certain conventions are not identical with those used in British Standards; attention is drawn especially to the following. The comma has been used as a decimal marker. In British Standards it is current practice to use a full point on the baseli
6、ne as the decimal marker. Wherever the words “International Standard” appear, referring to this standard, they should be read as “British Standard”. Additional information. No standard is quoted to refer to for sampling. Appropriate procedures will be incorporated in BS6200-2 “Methods of sampling an
7、d sample preparation”, which will be published in due course. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity fro
8、m legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages1 to 4, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendmen
9、t table on the inside front cover. Amendments issued since publication Amd. No. Date of issue CommentsBS 6200-3.1.5:1985 BSI 09-1999 i Contents Page National foreword Inside front cover 1 Scope and field of application 1 2 Principle 1 3 Reagents 1 4 Apparatus 1 5 Sample 2 6 Procedure 2 7 Expression
10、of results 3 8 Test report 3 Publication referred to Inside back coverii blankBS 6200-3.1.5:1985 BSI 09-1999 1 1 Scope and field of application This International Standard specifies a method for the determination of the aluminium content of ferrosilicon by flame atomic absorption spectroscopy. The m
11、ethod is applicable to ferrosilicon having an aluminium content between0,05 and5% (m/m). 2 Principle Dissolution of a test portion in nitric, hydrofluoric and perchloric acids. Evaporation of the solution until perchloric fumes are evolved. Separation and fusion of the residue with a mixture of sodi
12、um carbonate and boric acid; dissolution of the fused residue in the main solution. Aspiration of the solution in a dinitrogen monoxide-acetylene flame, and direct determination of the aluminium by absorption spectroscopy of the309,3nm line emitted by an aluminium hollow-cathode lamp. 3 Reagents Dur
13、ing the analysis, use only reagents of recognized analytical grade, and only distilled water or water of equivalent purity. 3.1 Sodium carbonate, anhydrous. 3.2 Nitric acid, 1,40g/ml, solution approximately68% (m/m). 3.3 Hydrofluoric acid, 1,16g/ml, solution approximately48% (m/m). 3.4 Perchloric ac
14、id, 1,68g/ml, solution approximately70% (m/m). 3.5 Hydrochloric acid, 1,19g/ml, solution approximately38% (m/m). 3.6 Hydrochloric acid, solution diluted1+9 Mix 1 volume of the hydrochloric acid solution (3.5) with9 volumes of water and stir to mix. 3.7 Boric acid, crystalline. 3.8 Iron solution No.
15、1, corresponding to10g of Fe per litre. Weigh, to the nearest0,001g, 10g of very pure, aluminium-free iron, transfer to a600ml beaker and dissolve in50ml of the hydrochloric acid solution (3.5). Heat gently until dissolution is complete. Transfer the contents of the beaker quantitatively into a1000m
16、l volumetric flask. Make up to the mark with water and mix. 3.9 Iron solution No. 2, corresponding to10g of Fe per litre. Weigh, to the nearest0,001g, 5g of very pure, aluminium-free iron, transfer to a600ml beaker and dissolve in25ml of the hydrochloric acid solution (3.5). Heat gently until dissol
17、ution is complete. Add25ml of the perchloric acid solution(3.4). Heat until white perchloric fumes are evolved. Cool, and add50ml of the hydrochloric acid solution (3.5). Wait until the solution becomes clear then add50ml of water. Plunge into this solution a platinum crucible, in which has previous
18、ly been melted a mixture of5g of the sodium carbonate(3.1) and2,5g of the boric acid (3.7), using a muffle furnace set at1000 C. Heat gently until complete dissolution of the melt residue. Withdraw the crucible from the beaker and rinse it carefully into the beaker. Cool. Transfer the contents of th
19、e beaker quantitatively into a500ml volumetric flask. Make up to mark with water and mix. 3.10 Solution used in calibration to restore the operating conditions of the analysis. Into a 250ml beaker place30ml of the hydrochloric acid solution (3.5), 15ml of perchloric acid (3.4) and50ml of water. Plun
20、ge into this solution a platinum crucible in which has previously been melted a mixture of5g of the sodium carbonate(3.1) and2,5g of the boric acid (3.7), using a muffle furnace set at1000 C. Heat slowly until complete dissolution of the melt residue. Withdraw the crucible from the beaker and rinse
21、it carefully into the beaker. Cool. Transfer the contents of the beaker quantitatively into a200ml volumetric flask. Make up to the mark with water and mix. 3.11 Aluminium, standard solution corresponding to1g of Al per litre Weigh, to the nearest0,001g, 1g of aluminium, purity99,99%. Transfer to a6
22、00ml beaker and dissolve in30ml of the hydrochloric acid solution(3.5). Transfer the solution quantitatively into a1000ml volumetric flask. Make up to the mark with water and mix. 4 Apparatus Usual laboratory equipment, and in particular: 4.1 Platinum crucibles, capacity approximately40ml. 4.2 Polyt
23、etrafluorethylene (PTFE) beakers or platinum dishes, of suitable capacity. 4.3 Atomic absorption spectrophotometer, equipped with a burner fed by dinitrogen monoxide and acetylene.BS 6200-3.1.5:1985 2 BSI 09-1999 4.4 Aluminium hollow-cathode lamp 5 Sample Sampling and preparation of samples of ferro
24、-alloys will form the subject of a subsequent International Standard. 6 Procedure WARNING Perchloric acid fumes may produce explosions in the presence of ammonia or organic substances in general. 6.1 Test portion Take a test portion of1 0,001g. 6.2 Blank test Carry out a blank test in parallel with
25、the determination, following the same procedure and using the same quantities of all the reagents, but use in all instances50ml of the iron solution No.1 (3.8). 6.3 Determination 6.3.1 Preparation of the test solution Transfer the test portion (6.1) to a150ml PTFE beaker or a platinum dish (4.2) of
26、capacity approximately100ml and add10ml of the nitric acid solution (3.2). Then add, carefully and gradually, shaking after each addition to enable the reaction to develop in a gradual manner, 10ml of the hydrofluoric acid solution (3.3). Let the reaction continue at room temperature until effervesc
27、ence ceases. If the silicon content of the sample is equal to or greater than65%, add to the solution so obtained30ml of the iron solution No.1 (3.8). In all cases add5ml of the perchloric acid solution(3.4). Place the beaker on a hot-plate, at a temperature not exceeding350 C, and heat until copiou
28、s white perchloric fumes are emitted. Cool. Add to the beaker30ml of the hydrochloric acid solution (3.6) and heat until all soluble salts have dissolved. Filter the residue, using a fine texture filter, and collect the filtrate in a250ml beaker. Wash the residue and the filter with about100ml of wa
29、rm water in order to remove the last trace of perchloric acid. Place the filter in a platinum crucible (4.1). Incinerate in a muffle furnace, set first of all at a low temperature, then calcine at1000 C for about15min. Allow to cool in a desiccator. Add to the crucible1g of the sodium carbonate (3.1
30、) and0,500g of the boric acid (3.7). Heat on a hot-plate, set at250 C, for15min. Place the crucible in a muffle furnace set at1000 C and leave for15min. Allow the crucible to cool, then place it in the beaker containing the filtrate from the residue of the acid attack. Add15ml of the hydrochloric ac
31、id solution(3.5) and heat gently until the melt residue completely dissolves. Withdraw the crucible from the beaker, rinse it carefully into the beaker, and concentrate the solution by moderate heating until a volume of about60ml is attained. Cool. Transfer the contents of the beaker quantitatively
32、into a100ml volumetric flask. Make up to the mark with water and mix. The preparation of solution A is thus complete. 6.3.1.1 ALUMINIUM CONTENTS OF LESS THAN 0,50% (m/m) Carry out the measurement specified in6.3.2 using solution A. 6.3.1.2 ALUMINIUM CONTENTS BETWEEN 0,50 AND 1,25% (m/m) Take 20ml of
33、 solution A and transfer to a50ml volumetric flask. Add, from a burette, 24ml of the iron solution No.2 (3.9). Make up to the mark with water and mix. The preparation of solution B is thus complete. Carry out the measurement specified in6.3.2 using solution B. 6.3.1.3 ALUMINIUM CONTENTS BETWEEN 1,25
34、 AND 5% (m/m) Take 5ml of solution A and transfer to a50ml volumetric flask. Add, from a burette, 36ml of the iron solution No.2 (3.9). Make up to the mark with water and mix. The preparation of solution C is thus complete. Carry out the measurement specified in6.3.2 using solution C. NOTEDepending
35、upon the sensitivity of the equipment used, greater dilutions can be accommodated. 6.3.2 Spectrometric measurement Switch on the flame atomic absorption spectrometer (4.3) and the aluminium hollow-cathode lamp (4.4) a sufficient time in advance to ensure their stability.BS 6200-3.1.5:1985 BSI 09-199
36、9 3 Adjust the wavelength to309,3nm. Adjust the pressure of the dinitrogen monoxide and the acetylene according to the burner characteristics. Obtain the optimum signal using an aluminium solution of known concentration, which may vary according to the apparatus, to obtain maximum sensitivity and st
37、ability. Measure the absorbance of the test solution (6.3.1.1 or6.3.1.2 or6.3.1.3) after having adjusted the instrument zero reading with respect to the solution for the blank test on the reagents for the calibration curve (6.4). Prepare a calibration curve (see6.4) for each series of measurements.
38、NOTEAluminium is partly ionized in the dinitrogen monoxide-acetylene flame. Iron acts as an ionization buffer and thus enhances the signal from aluminium. Trials have shown that under the conditions used, the enhancement is constant for a range of3 to10g of Fe per litre. 6.4 Establishment of the cal
39、ibration curve To each of a series of eight 100 ml volumetric flasks transfer: 50 ml of the iron solution No. 2 (3.9), and 20 ml of the solution for restoration of the operating conditions of the analysis (3.10). Then add respectively the volumes of the standard aluminium solution (3.11) given in th
40、e table below: Make up to volume with water and mix. Carry out the absorbance measurements on each reference solution under the conditions specified in6.3.2. Plot the calibration curve, indicating as abscissae the percentages by mass of aluminium in the ferrosilicon, and as ordinates the correspondi
41、ng absorbance values. 7 Expression of results Calculate, using the calibration curve, the percentage by mass of aluminium in the ferrosilicon corresponding to the absorbance measured. 8 Test report The test report shall include the following particulars: a) identification of the sample; b) the refer
42、ence of the method used; c) the results and the method of expression used; d) any unusual features noted during the determination; e) any operation not included in this International Standard or regarded as optional. Standard aluminium solution (3.11) Corresponding mass of aluminium Corresponding pe
43、rcentage by mass of aluminium in the test portion ml mg Solution A1g/ 100ml Solution B1g/ 250ml Solution C1g/ 1000ml 0 a 0 0 0 0 0,50 0,5 0,05 0,125 0,50 1,00 1,0 0,10 0,25 1,00 2,00 2,0 0,20 0,50 2,00 2,50 2,5 0,25 0,625 2,50 3,00 3,0 0,30 0,75 3,00 4,00 4,0 0,40 1,00 4,00 5,00 5,0 0,50 1,25 5,00 a
44、 Blank test on the reagents for the calibration curve.4 blankBS 6200-3.1.5:1985 BSI 09-1999 Publication referred to See national foreword.BS 6200-3.1.5: 1985 ISO 4139:1979 BSI 389 Chiswick High Road London W4 4AL BSIBritishStandardsInstitution BSI is the independent national body responsible for pre
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