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1、BRITISH STANDARD BS 6200-3.24.2: 1992 Sampling and analysis of iron, steel and other ferrous metals Part 3: Methods of analysis Section 3.24 Determination of phosphorus Subsection 3.24.2 Ferrochromium, ferromanganese and ferromolybdenum: spectrophotometric method Licensed Copy: sheffieldun sheffield
2、un, na, Wed Dec 06 15:08:22 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6200-3.24.2:1992 This British Standard, having been prepared under the direction of the Iron and Steel Standards Policy Committee, was published under the authority of the Standards Board and comes into effect on 15 June 1992
3、BSI 09-1999 The following BSI references relate to the work on this standard: Committee reference ISM/18 Draft for comment 91/44342 DC ISBN 0 580 20798 6 Committees responsible for this British Standard The preparation of this British Standard was entrusted by the Iron and Steel Standards Policy Com
4、mittee (ISM/-) to Technical Committee ISM/18, upon which the following bodies were represented: BCIRA British Steel Industry Department of Trade and Industry (Laboratory of the Government Chemist) Ferro Alloys and Metals Producers Association Ministry of Defence Amendments issued since publication A
5、md. No.DateComments Licensed Copy: sheffieldun sheffieldun, na, Wed Dec 06 15:08:22 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6200-3.24.2:1992 BSI 09-1999i Contents Page Committees responsibleInside front cover Forewordii 1Scope1 2Principle1 3Reagents1 4Apparatus1 5Sampling1 6Procedure1 7Calcula
6、tion and expression of results3 8Test report3 Table 1 Calibration data2 Table 2 Precision data3 Table 3 Predicted values of r and R3 Publication(s) referred toInside back cover Licensed Copy: sheffieldun sheffieldun, na, Wed Dec 06 15:08:22 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6200-3.24.2:1
7、992 ii BSI 09-1999 Foreword This Subsection of BS 6200 has been prepared under the direction of the Iron and Steel Standards Policy Committee and supersedes method 3 for the determination of phosphorus in BSI Handbook No. 19, to which it is technically equivalent. BS 6200 is a multipart British Stan
8、dard, covering all aspects of the sampling and analysis of iron, steel and other ferrous metals. A list of contents, together with general information, is given in Part 1. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are respon
9、sible 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, pages 1 to 4, an inside back cover and a back cover. This standard has bee
10、n updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover. Licensed Copy: sheffieldun sheffieldun, na, Wed Dec 06 15:08:22 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6200-3.24.2:1992 BSI 09-19991 1 Scope This S
11、ubsection of BS 6200 describes a spectrophotometric method for the determination of phosphorus in ferrochromium, ferromanganese, and ferromolybdenum. The method is applicable to the range of phosphorus contents normally found in these alloys. NOTEThe titles of the publications referred to in this Su
12、bsection of BS 6200 are listed on the inside back cover. 2 Principle After dissolving the sample in an oxidizing acid mixture, or in the case of high carbon ferrochromium after decomposition by fusion with disodium peroxide, the phosphorus is converted to phosphovanadomolybdate in perchloric-nitric
13、solution. With citric acid present to complex arsenic, the phosphovanadomolybdate is extracted into 4-methylpentan-2-one and determined spectrophotometrically. 3 Reagents During the analysis use only reagents of recognized analytical grade and only grade 3 water as specified in BS 3978. NOTEIt is es
14、sential that only reagents low in phosphorus are used. 3.1 Ammonium molybdate solution, 150 g/l. Dissolve 75 g of ammonium molybdate, (NH4)6Mo7O24.4H2O, in water, dilute to 500 ml and mix. 3.2 Ammonia solution, diluted 1 + 1. To 500 ml of water add 500 ml of ammonia solution, density = 0.91 g/ml, an
15、d mix. 3.3 Ammonia solution, diluted 3 + 97. To 500 ml of water add 30 ml of ammonia solution, = 0.91 g/ml, dilute to 1 l and mix. 3.4 Ammonium metavanadate solution, 2.5 g/l. Dissolve 1.25 g of ammonium metavanadate in water, dilute to 500 ml and mix. 3.5 Citric acid solution, 500 g/l. Dissolve 125
16、 g of citric acid, H8C6O7.H2O, in water, dilute to 250 ml and mix. 3.6 Disodium peroxide 3.7 Hydrochloric acid, = 1.16 g/ml to 1.18 g/ml. 3.8 Hydrochloric acid, = 1.16 g/ml to 1.18 g/ml, diluted 1 + 1. 3.9 Iron, high purity, containing 0.001 % (m/m) phosphorus, or less. 3.10 4-Methylpentan-2-one (al
17、so known as isobutyl methyl ketone). 3.11 Nitric acid, = 1.42 g/ml. 3.12 Nitric acid, = 1.42 g/ml, diluted 1 + 4. 3.13 Perchloric acid, = 1.54 g/ml. Use a low phosphorus grade. 3.14 Potassium permanganate solution, 10 g/l. Dissolve 1 g of potassium permanganate in water, dilute to 100 ml and mix. 3.
18、15 Phosphorus, standard solution, equivalent to 0.01 mg of phosphorus per millilitre. Dissolve 0.4393 g of potassium dihydrogen orthophosphate, previously dried to constant weight at 105 C, in water. Cool, transfer to a 1 l volumetric flask, dilute to the mark and mix. Transfer 100 ml of this soluti
19、on to a 1 l volumetric flask, dilute to the mark and mix. 3.16 Sodium nitrite solution, 50 g/l. Dissolve 25 g of sodium nitrite in water, dilute to 500 ml and mix. 3.17 Sulfuric acid, diluted 1 + 3. To 500 ml of water, add cautiously and with cooling and stirring, 250 ml of sulfuric acid, = 1.84 g/m
20、l. Dilute to 1 l and mix. 4 Apparatus 4.1 Ordinary laboratory apparatus 4.2 Volumetric glassware, in accordance with class A of BS 846, BS 1583 or BS 1792, as appropriate. 4.3 Spectrophotometer, suitable for measuring absorbance at a wavelength of 425 nm. 4.4 Cells, having an optical path length of
21、2 cm. 5 Sampling Carry out sampling in accordance with BS 1837. NOTEBS 6200-2, which will supersede BS 1837, is currently in course of preparation. On its publication this Subsection will be amended to include sampling in accordance with BS 6200-2. 6 Procedure 6.1 Test portion Weigh, to the nearest
22、0.001 g, a test portion of 0.5 g. 6.2 Blank test In parallel with the determination and following the same procedure, carry out a blank test using the same quantities of all reagents. Licensed Copy: sheffieldun sheffieldun, na, Wed Dec 06 15:08:22 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6200-3
23、.24.2:1992 2 BSI 09-1999 6.3 Determination 6.3.1 Preparation of the test solution of high carbon ferrochromium by fusion Place the test portion in a nickel crucible containing 5 g of disodium peroxide (3.6). Mix and fuse. Cool, and extract the melt by boiling with 100 mL of water. Rinse and remove t
24、he crucible. Acidify with nitric acid (3.12) and boil to dissolve soluble salts. Then neutralize with ammonia solution (3.2) and add sufficient excess to completely precipitate iron(III) hydroxide and phosphate. Filter through an open-texture filter paper and wash with ammonia solution (3.3). NOTEA
25、Whatman No. 541 paper is suitable. Dissolve the precipitate from the paper with hot hydrochloric acid (3.8) into the original beaker and rinse with hot water. Continue as in 6.3.3. 6.3.2 Preparation of the test solution of other ferroalloys by dissolution in acid Place the test portion in a 125 ml c
26、onical beaker, add a mixture of 5 ml of nitric acid (3.11) and 5 ml of hydrochloric acid (3.7), cover the beaker and heat until solvent action ceases. For samples which do not dissolve readily in this mixture (for example low carbon ferrochromium) make further additions of 5 ml of hydrochloric acid
27、(3.7), up to a maximum of 20 ml. For phosphorus contents greater than 0.08 % (m/m), for example in ferromanganese, transfer the solution to a 200 mL volumetric flask, dilute to the mark and mix. Take a suitable aliquot containing not more than 0.4 mg of phosphorus. 6.3.3 Oxidation of chromium with p
28、erchloric acid To the solution obtained in accordance with 6.3.1 or 6.3.2, add 10 ml of perchloric acid (3.13). In the case of ferromolybdenum, substitute 10 ml of sulfuric acid (3.17). Evaporate to fuming and continue for 5 min to 10 min at a temperature such that there is a steady reflux of perchl
29、oric acid on the walls of the beaker, or that strong fumes of sulfur trioxide are maintained. For low carbon ferrochromium, remove most of the chromium, when fully oxidized by the fuming perchloric acid, by addition of 5 ml of hydrochloric acid (3.7). Continue fuming until the chromium is again full
30、y oxidized and then repeat the treatment with hydrochloric acid (3.7). Finally repeat the fuming to leave the small residual amount of chromium fully oxidized. 6.3.4 Formation of the phosphovanadomolybdate complex Cool, add 25 ml of nitric acid (3.12) and a few glass beads, then boil for 1 min or 2
31、min. Add 5 ml of potassium permanganate solution (3.14), boil for 2 min, then add 10 ml of sodium nitrite solution (3.16) and boil until freed from nitrous fumes. Cool to approximately 20 C, add 10 ml of ammonium metavanadate solution (3.4) and 15 ml of ammonium molybdate solution (3.1), mix and all
32、ow to stand for a minimum of 7 min. NOTEIt is recommended that the above and all subsequent additions of reagents are made by pipette, safety pipette where appropriate, or burette. 6.3.5 Solvent extraction of the phosphovanadomolybdate complex Transfer the solution to a stoppered 250 ml separating f
33、unnel marked at 100 ml, dilute to the mark with water and mix. Add 10 ml of citric acid (3.5), mix and immediately add 40 ml of 4-methylpentan-2-one (3.10). Stopper and shake the funnel for 30 s. Allow the two layers to separate and discard the lower (aqueous) layer. Dry the inside of the stem of th
34、e separating funnel with a small piece of filter paper. Filter the ketone layer through a dry rapid paper into a small dry beaker. NOTEA Whatman No. 541 paper is suitable. 6.3.6 Measurement of absorbance Measure the absorbance of the 4-methylpentan-2-one layer, at 20 1 C, in a 2 cm cell (4.4) using
35、the spectrophotometer (4.3) at a wavelength of 425 nm. Measure the absorbance of the blank solution under the same conditions. 6.4 Preparation of the calibration graph Weigh and transfer 0.5 g portions of high purity iron (3.9) to a number of 125 ml conical beakers and make additions of phosphorus s
36、tandard solution (3.15) as shown in Table 1. Table 1 Calibration data Phosphorus solutionPhosphorus equivalent ml 0.0 5.0 10.0 15.0 20.0 25.0 30.0 35.0 40.0 % (m/m) nil 0.010 0.020 0.030 0.040 0.050 0.060 0.070 0.080 Licensed Copy: sheffieldun sheffieldun, na, Wed Dec 06 15:08:22 GMT+00:00 2006, Unc
37、ontrolled Copy, (c) BSI BS 6200-3.24.2:1992 BSI 09-19993 Table 2 Precision data Treat as described in 6.3.2 to 6.3.6. Prepare a calibration graph by plotting the absorbance of each solution against the equivalent percentage of phosphorus. 7 Calculation and expression of results 7.1 Calculation Read
38、the phosphorus content of the blank and the test portion from the calibration graph (see 6.4) and make the appropriate correction. If an aliquot was taken in 6.3.2, multiply the result by the ratio of the total volume of 200 ml to the volume in millilitres of the aliquot. 7.2 Precision 7.2.1 Precisi
39、on data A planned trial of the method was carried out by five analysts, each from a different laboratory; six determinations were made by each analyst on each of five samples. From the results obtained, the 95 % confidence limits have been calculated in accordance with BS 5497-1 and are given in Tab
40、le 2. The difference between two single results found on identical material by one analyst using the same apparatus within a short time interval will exceed the repeatability r, on average, not more than once in 20 cases in the normal and correct operation of the method. The difference between two s
41、ingle and independent results found by two operators working in different laboratories on identical test material will exceed the reproducibility R, on average, not more than once in 20 cases in the normal and correct operation of the method. 7.2.2 Regression data Statistical analysis of the results
42、 showed a logarithmic relationship between phosphorus content P and the values of repeatability r and reproducibility R summarized by the following logarithmic regression equations: log r = 0.6473 log P 1.7377 correlation coefficient = 0.937 log R = 0.8001 log P 1.2956 correlation coefficient = 0.97
43、6 The predicted values of r and R from these equations are shown in Table 3. Table 3 Predicted values of r and R 8 Test report The test report shall include the following information: a) all information necessary for the identification of the sample, the laboratory and the date of analysis; b) the m
44、ethod used, by reference to this Subsection of BS 6200; c) the results, and the form in which they are expressed; d) any unusual features noted during the determination; e) any operation not specified in this British Standard or any optional operation which may have influenced the results. Alloy typ
45、ePhosphorusRepeatability rReproducibility R High carbon ferrochromium Low carbon ferrochromium Ferromolybdenum High carbon ferromanganese Low carbon ferromanganese % (m/m) 0.018 0.025 0.08 0.23 0.31 0.0017 0.0017 0.0021 0.0085 0.0096 0.0024 0.0027 0.0045 0.017 0.023 PhosphorusRepeatability, rReprodu
46、cibility, R % (m/m) 0.02 0.05 0.10 0.20 0.30 0.0015 0.0026 0.0041 0.0065 0.0084 0.0022 0.0046 0.0080 0.014 0.019 Licensed Copy: sheffieldun sheffieldun, na, Wed Dec 06 15:08:22 GMT+00:00 2006, Uncontrolled Copy, (c) BSI 4 blank Licensed Copy: sheffieldun sheffieldun, na, Wed Dec 06 15:08:22 GMT+00:0
47、0 2006, Uncontrolled Copy, (c) BSI BS 6200-3.24.2:1992 BSI 09-1999 Publication(s) referred to BS 846, Specification for burettes. BS 1583, Specification for one-mark pipettes. BS 1792, Specification for one-mark volumetric flasks. BS 1837, Methods for the sampling of iron, steel, permanent magnet al
48、loys and ferro-alloys. BS 3978, Specification for water for laboratory use. BS 5497, Precision of test methods. BS 5497-1, Guide for the determination of repeatability and reproducibility for a standard test method by inter-laboratory tests. BS 6200, Sampling and analysis of iron, steel and other fe
49、rrous metals. BS 6200-1, Introduction and contents1). BS 6200-2, Methods of sampling and sample preparation2). BSI Handbook No. 19, Methods for the sampling and analysis of iron, steel and other ferrous metals1). 1) Referred to in the foreword only. 2) In preparation. Licensed Copy: sheffieldun sheffieldun, na, Wed Dec 06 15:08:22 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6200-3.24.2: 1992 BSI 389 Chiswick High Road London W4 4AL BSI British Standards Institution BSI is the independent national body responsible for preparing Briti