1、BRITISH STANDARD BS 6200-3.24.2: 1992 Sampling and analysis of iron, steel and other ferrous metals Part3: Methods of analysis Section3.24 Determination of phosphorus Subsection3.24.2 Ferrochromium, ferromanganese and ferromolybdenum: spectrophotometric methodBS6200-3.24.2:1992 This British Standard
2、, having been prepared under the directionof the Iron and Steel Standards Policy Committee, waspublished under the authorityof the Standards Boardand comes into effect on 15June1992 BSI09-1999 The following BSI references relate to the work on this standard: Committee reference ISM/18 Draft for comm
3、ent91/44342DC 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 Committee (ISM/-) to Technical Committee ISM/18, upon which the following bodies were represented: BCIRA British Steel Indus
4、try Department of Trade and Industry (Laboratory of the Government Chemist) Ferro Alloys and Metals Producers Association Ministry of Defence Amendments issued since publication Amd. No. Date CommentsBS6200-3.24.2:1992 BSI 09-1999 i Contents Page Committees responsible Inside front cover Foreword ii
5、 1 Scope 1 2 Principle 1 3 Reagents 1 4 Apparatus 1 5 Sampling 1 6 Procedure 1 7 Calculation and expression of results 3 8 Test report 3 Table 1 Calibration data 2 Table 2 Precision data 3 Table 3 Predicted values of r and R 3 Publication(s) referred to Inside back coverBS6200-3.24.2:1992 ii BSI 09-
6、1999 Foreword This Subsection of BS6200 has been prepared under the direction of the Iron and Steel Standards Policy Committee and supersedes method3 for the determination of phosphorus in BSI Handbook No.19, to which it is technically equivalent. BS6200 is a multipart British Standard, covering all
7、 aspects of the sampling and analysis of iron, steel and other ferrous metals. A list of contents, together with general information, is given in Part1. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their cor
8、rect 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, pagesi andii, pages1 to4, an inside back cover and a back cover. This standard has been updated (see copyrigh
9、t date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover.BS6200-3.24.2:1992 BSI 09-1999 1 1 Scope This Subsection of BS6200 describes a spectrophotometric method for the determination of phosphorus in ferrochromium, ferromanganese, and
10、 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 Subsection of BS6200 are listed on the inside back cover. 2 Principle After dissolving the sample in an oxidizing acid mixture, or in
11、the case of high carbon ferrochromium after decomposition by fusion with disodium peroxide, the phosphorus is converted to phosphovanadomolybdate in perchloric-nitric solution. With citric acid present to complex arsenic, the phosphovanadomolybdate is extracted into4-methylpentan-2-one and determine
12、d spectrophotometrically. 3 Reagents During the analysis use only reagents of recognized analytical grade and only grade3 water as specified in BS3978. NOTEIt is essential that only reagents low in phosphorus are used. 3.1 Ammonium molybdate solution,150g/l. Dissolve75g of ammonium molybdate, (NH 4
13、) 6 Mo 7 O 24 .4H 2 O, in water, dilute to500ml and mix. 3.2 Ammonia solution, diluted1+1. To500ml of water add500ml of ammonia solution, density =0.91g/ml, and mix. 3.3 Ammonia solution, diluted3+97. To500ml of water add30ml of ammonia solution, =0.91g/ml, dilute to1 l and mix. 3.4 Ammonium metavan
14、adate solution,2.5g/l. Dissolve1.25g of ammonium metavanadate in water, dilute to500ml and mix. 3.5 Citric acid solution,500g/l. Dissolve125g of citric acid, H 8 C 6 O 7 .H 2 O, in water, dilute to250ml and mix. 3.6 Disodium peroxide 3.7 Hydrochloric acid, =1.16g/ml to1.18g/ml. 3.8 Hydrochloric acid
15、, =1.16g/ml to1.18g/ml, diluted1+1. 3.9 Iron, high purity, containing0.001%(m/m) phosphorus, or less. 3.10 4-Methylpentan-2-one (also known as isobutyl methyl ketone). 3.11 Nitric acid, =1.42g/ml. 3.12 Nitric acid, =1.42g/ml, diluted1+4. 3.13 Perchloric acid, =1.54g/ml. Use a low phosphorus grade. 3
16、.14 Potassium permanganate solution,10g/l. Dissolve1g of potassium permanganate in water, dilute to100ml and mix. 3.15 Phosphorus, standard solution, equivalent to0.01mg of phosphorus per millilitre. Dissolve0.4393g of potassium dihydrogen orthophosphate, previously dried to constant weight at105 C,
17、 in water. Cool, transfer to a1 l volumetric flask, dilute to the mark and mix. Transfer100ml of this solution to a1 l volumetric flask, dilute to the mark and mix. 3.16 Sodium nitrite solution,50g/l. Dissolve25g of sodium nitrite in water, dilute to500ml and mix. 3.17 Sulfuric acid, diluted1+3. To5
18、00ml of water, add cautiously and with cooling and stirring,250ml of sulfuric acid, =1.84g/ml. Dilute to1l and mix. 4 Apparatus 4.1 Ordinary laboratory apparatus 4.2 Volumetric glassware, in accordance with classA of BS846, BS1583 or BS1792, as appropriate. 4.3 Spectrophotometer, suitable for measur
19、ing absorbance at a wavelength of425nm. 4.4 Cells, having an optical path length of2cm. 5 Sampling Carry out sampling in accordance with BS1837. NOTEBS6200-2, which will supersede BS1837, is currently in course of preparation. On its publication this Subsection will be amended to include sampling in
20、 accordance with BS6200-2. 6 Procedure 6.1 Test portion Weigh, to the nearest0.001g, a test portion of0.5g. 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.BS6200-3.24.2:1992 2 BSI 09-1999 6.3 Determ
21、ination 6.3.1 Preparation of the test solution of high carbon ferrochromium by fusion Place the test portion in a nickel crucible containing5g of disodium peroxide(3.6). Mix and fuse. Cool, and extract the melt by boiling with100mL of water. Rinse and remove the crucible. Acidify with nitric acid(3.
22、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 Whatman No.541 paper is suitable. Dissolve
23、the precipitate from the paper with hot hydrochloric acid(3.8) into the original beaker and rinse with hot water. Continue as in6.3.3. 6.3.2 Preparation of the test solution of other ferroalloys by dissolution in acid Place the test portion in a125ml conical beaker, add a mixture of5ml of nitric aci
24、d(3.11) and5ml 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 of5ml of hydrochloric acid(3.7), up to a maximum of20ml. For phosphorus contents gr
25、eater than0.08%(m/m), for example in ferromanganese, transfer the solution to a200mL volumetric flask, dilute to the mark and mix. Take a suitable aliquot containing not more than0.4mg of phosphorus. 6.3.3 Oxidation of chromium with perchloric acid To the solution obtained in accordance with6.3.1 or
26、6.3.2, add10ml of perchloric acid(3.13). In the case of ferromolybdenum, substitute10ml of sulfuric acid(3.17). Evaporate to fuming and continue for5min to10min at a temperature such that there is a steady reflux of perchloric acid on the walls of the beaker, or that strong fumes of sulfurtrioxide a
27、re maintained. For low carbon ferrochromium, remove most of the chromium, when fully oxidized by the fuming perchloric acid, by addition of5ml of hydrochloric acid(3.7). Continue fuming until the chromium is again fully oxidized and then repeat the treatment with hydrochloric acid(3.7). Finally repe
28、at the fuming to leave the small residual amount of chromium fully oxidized. 6.3.4 Formation of the phosphovanadomolybdate complex Cool, add25ml of nitric acid(3.12) and a few glass beads, then boil for1min or2min. Add5ml of potassium permanganate solution(3.14), boil for2min, then add10ml of sodium
29、 nitrite solution(3.16) and boil until freed from nitrous fumes. Cool to approximately20 C, add10ml of ammonium metavanadate solution(3.4) and15ml of ammonium molybdate solution(3.1), mix and allow to stand for a minimum of7min. NOTEIt is recommended that the above and all subsequent additions of re
30、agents are made by pipette, safety pipette where appropriate, or burette. 6.3.5 Solvent extraction of the phosphovanadomolybdate complex Transfer the solution to a stoppered250ml separating funnel marked at100ml, dilute to the mark with water and mix. Add10ml of citricacid(3.5), mix and immediately
31、add40ml of4-methylpentan-2-one(3.10). Stopper and shake the funnel for30s. Allow the two layers to separate and discard the lower (aqueous) layer. Dry the inside of the stem of the separating funnel with a small piece of filter paper. Filter the ketone layer through a dry rapid paper into a small dr
32、y beaker. NOTEA Whatman No.541 paper is suitable. 6.3.6 Measurement of absorbance Measure the absorbance of the4-methylpentan-2-one layer, at20 1 C, in a2cm cell(4.4) using the spectrophotometer(4.3) at a wavelength of425nm. Measure the absorbance of the blank solution under the same conditions. 6.4
33、 Preparation of the calibration graph Weigh and transfer0.5g portions of high purity iron(3.9) to a number of125ml conical beakers and make additions of phosphorus standard solution(3.15) as shown in Table 1. Table 1 Calibration data Phosphorus solution Phosphorus equivalent ml 0.0 5.0 10.0 15.0 20.
34、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 0.080BS6200-3.24.2:1992 BSI 09-1999 3 Table 2 Precision data Treat as described in6.3.2 to6.3.6. Prepare a calibration graph by plotting the absorbance of each solution against the equivalent percentage of phosphorus. 7 Calc
35、ulation and expression of results 7.1 Calculation Read the phosphorus content of the blank and the test portion from the calibration graph (see6.4) and make the appropriate correction. If an aliquot was taken in6.3.2, multiply the result by the ratio of the total volume of200ml to the volume in mill
36、ilitres of the aliquot. 7.2 Precision 7.2.1 Precision 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, the95% confidence limits have been calculated
37、in accordance with BS5497-1 and are given in Table 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 in20 cases in the normal and correct operat
38、ion of the method. The difference between two single 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 in20 cases in the normal and correct operation of the method. 7.2.2 Regre
39、ssion data Statistical analysis of the results showed a logarithmic relationship between phosphorus content P and the values of repeatability r and reproducibility R summarized by the following logarithmic regression equations: logr =0.6473logP 1.7377 correlation coefficient =0.937 logR =0.8001logP
40、1.2956 correlation coefficient =0.976 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 laborator
41、y and the date of analysis; b) the method used, by reference to this Subsection of BS6200; 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 BritishStandard or any optional operation which may have
42、 influenced the results. Alloy type Phosphorus Repeatability r Reproducibility 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.
43、023 Phosphorus Repeatability, r Reproducibility, 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 0.0194 blankBS6200-3.24.2:1992 BSI 09-1999 Publication(s) referred to BS846, Specification for burettes. BS1583, Specification for one-mark pipettes. BS17
44、92, Specification for one-mark volumetric flasks. BS1837, Methods for the sampling of iron, steel, permanent magnet alloys and ferro-alloys. BS3978, Specification for water for laboratory use. BS5497, Precision of test methods. BS5497-1, Guide for the determination of repeatability and reproducibili
45、ty for a standard test method by inter-laboratory tests. BS6200, Sampling and analysis of iron, steel and other ferrous metals. BS6200-1, Introduction and contents 1) . BS6200-2, Methods of sampling and sample preparation 2) . BSI Handbook No.19, Methods for the sampling and analysis of iron, steel
46、and other ferrous metals 1) . 1) Referred to in the foreword only. 2) In preparation.BS 6200-3.24.2: 1992 BSI 389 Chiswick High Road London W4 4AL BSIBritishStandardsInstitution BSI is the independent national body responsible for preparing BritishStandards. It presents the UK view on standards in E
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