《BS-6200-3.11.2-1991.pdf》由会员分享，可在线阅读，更多相关《BS-6200-3.11.2-1991.pdf（12页珍藏版）》请在三一文库上搜索。
1、BRITISH STANDARD BS 6200-3.11.2: 1991 Sampling and analysis of iron, steel and other ferrous metals Part 3: Methods of analysis Section 3.11 Determination of cobalt Subsection 3.11.2 Steel, irons and steelmaking materials: spectrophotometric method for trace amounts Licensed Copy: sheffieldun sheffi
2、eldun, na, Wed Dec 06 15:04:02 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6200-3.11.2:1991 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 20 Decembe
3、r 1991 BSI 09-1999 The following BSI references relate to the work on this standard: Committee reference ISM/18 Draft for comment 91/38344 DC ISBN 0 580 20228 3 Committees responsible for this British Standard The preparation of this British Standard was entrusted by the Iron and Steel Standards Pol
4、icy Committee (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 public
5、ation Amd. No.DateComments Licensed Copy: sheffieldun sheffieldun, na, Wed Dec 06 15:04:02 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6200-3.11.2:1991 BSI 09-1999i Contents Page Committees responsibleInside front cover Forewordii 1Scope1 2Principle1 3Reagents1 4Apparatus1 5Sampling1 6Procedure1 7
6、Calculation and expression of results3 8Test report4 Appendix A Application to steelmaking materials5 Table 1 Calibration data for optical path lengths, additions of cobalt solution (3.2) and equivalent cobalt percentage by mass3 Table 2 Precision data from steels and irons3 Table 3 Regression data
7、for steels and irons: values for inter-laboratory agreement (2.83Sb, P = 95 %)4 Table 4 Precision data from steelmaking materials5 Table 5 Regression data for steelmaking materials: values for inter-laboratory agreement (2.83Sb, P = 95 %)5 Publication(s) referred toInside back cover Licensed Copy: s
8、heffieldun sheffieldun, na, Wed Dec 06 15:04:02 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6200-3.11.2:1991 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 2 for the determination of co
9、balt in BSI Handbook No. 19, to which it is technically equivalent. BS 6200 is a multipart British Standard, 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 n
10、ot 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 from legal obligations. Summary of pages This document comprises a front cover, an inside
11、front cover, pages i and ii, pages 1 to 6, 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 amendment table on the inside front cover. Licensed Copy: sheffieldun sheffieldun, na, Wed Dec
12、 06 15:04:02 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6200-3.11.2:1991 BSI 09-19991 1 Scope This Subsection of BS 6200 describes a spectrophotometric method for the determination of trace amounts of cobalt in steel, iron, and steelmaking materials. The method is applicable to cobalt contents fr
13、om 0.002 % (m/m) to 0.04 % (m/m). NOTEThe titles of the publications referred to in this Subsection of BS 6200 are listed on the inside back cover. 2 Principle The test portion is dissolved in hydrochloric acid and oxidized with nitric acid. Iron and chromium are removed with zinc oxide. Cobalt is s
14、eparated from nickel using 1-nitroso-2-naphthol, with a small addition of iron as a carrier. After ignition, the residue is dissolved in acid and the reddish-brown coloured complex of cobalt with nitroso-R-salt is developed in a phosphoric-sulfuric acid solution buffered with sodium acetate. Complex
15、es of interfering elements are decomposed with nitric acid and the cobalt complex is evaluated spectrophotometrically. 3 Reagents During the analysis, use only reagents of recognized analytical grades and only grade 3 water as specified in BS 3978. 3.1 Cobalt standard solution, 1 mg cobalt per milli
16、litre. Dissolve 1 g of high purity cobalt sheet in 20 mL of nitric acid (3.6). Cool, transfer to a 1 L volumetric flask, dilute to the mark and mix. 3.2 Cobalt standard solution, 0.025 mg cobalt per millilitre. By means of a pipette, transfer 25 mL of cobalt solution (3.1) to a 1 L volumetric flask,
17、 dilute to the mark and mix. 3.3 Hydrochloric acid, density = 1.16 g/mL to 1.18 g/mL. 3.4 Hydrochloric acid, = 1.16 g/mL to 1.18 g/mL, diluted 1 + 9. 3.5 Iron(III) chloride solution, 5 mg iron per millilitre. Dissolve 0.5 g of high purity iron free from cobalt in 20 mL of hydrochloric acid (3.3), he
18、at to boiling, oxidize with the minimum amount of nitric acid (3.6), and continue boiling to expel nitrous fumes. Cool, dilute to 100 mL and mix. 3.6 Nitric acid, = 1.42 g/mL. 3.7 Nitric acid, = 1.42 g/mL, diluted 1 + 1. To 50 mL of water add 50 mL of nitric acid (3.6) and mix. 3.8 1-nitroso-2-napht
19、hol solution. Dissolve 7 g of 1-nitroso-2-naphthol in 100 mL of acetic acid, = 1.049 g/mL. Prepare this solution immediately before use. 3.9 Nitroso-R-salt, 3 g/L solution. Dissolve 0.3 g of nitroso-R-salt, (sodium 1-nitroso-2-naphthol-3,6 disulfonate), in water, dilute to 100 mL and mix. Prepare th
20、is solution immediately before use. 3.10 Perchloric acid, = 1.54 g/mL. 3.11 Phosphoric-sulfuric acid mixture. To 600 mL of water, add cautiously 150 mL of phosphoric acid, = 1.75 g/mL, 150 mL of sulfuric acid = 1.84 g/mL, and mix. Cool, dilute to 1 L and mix. 3.12 Sodium acetate, 500 g/L solution. D
21、issolve 500 g of sodium acetate, CH3COONa.3H2O, in water, dilute to 1 L and mix. 3.13 Sulfuric acid, = 1.84 g/mL, diluted 1 + 1. To 400 mL of water, add cautiously, 500 mL of sulfuric acid = 1.84 g/mL, with cooling and stirring. Cool, dilute to 1 L and mix. 3.14 Sulfurous acid. Pass sulfur dioxide g
22、as into 1 L of water until a saturated solution is obtained. 3.15 Zinc oxide suspension. To 200 mL of water, add 50 g of finely powdered zinc oxide, and stir or shake until a smooth cream is obtained. Stir the suspension immediately before use, and also between additions during use. 4 Apparatus 4.1
23、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 525 nm. 4.4 Cells, having optical path lengths of 4 cm or 2 cm. 5 Sampling Carry out sampling
24、in accordance with BS 1837. Prepare samples with cobalt-free cutting tools. NOTEBS 6200-2, which will supersede BS 1837, is currently in 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 neares
25、t 0.001 g, a test portion of 2.5 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 reagents. NOTEThe blank is usually less than 0.0005 % (m/m) cobalt. Licensed Copy: sheffieldun sheffieldun, na, Wed Dec 06 15:04
26、:02 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6200-3.11.2:1991 2 BSI 09-1999 6.3 Determination 6.3.1 Preparation of the test solution NOTESee Appendix A for modifications to this procedure for particular steelmaking materials. Place the test portion in a 650 mL conical beaker. Add 20 mL of hydro
27、chloric acid (3.3), cover the beaker and heat until solvent action ceases. Oxidize with nitric acid (3.6). For high chromium steels only (for example more than 10 % (m/m) chromium) follow the procedure described in 6.3.2. Evaporate to approximately 10 mL, add 30 mL of water, cool, and dilute to appr
28、oximately 300 mL. 6.3.2 Removal of chromium Boil to remove nitrous fume and add 30 mL of perchloric acid (3.10). Evaporate to fumes and continue fuming until the chromium is oxidized. Add dropwise approximately 1 mL of hydrochloric acid (3.3), then reheat until the residual chromium is re-oxidized.
29、Repeat the treatment with hydrochloric acid followed by intermediate heating to fuming three or four times until most of the chromium has been volatilized. Cool, add 50 mL of water and heat to dissolve salts, and add a few drops of sulfurous acid (3.14) to reduce residual chromate. Boil to remove ex
30、cess of sulfur dioxide, add 1 mL of nitric acid (3.6), and boil again to re-oxidize any reduced iron. Cool and dilute to approximately 300 mL. Continue as described in 6.3.3. 6.3.3 Zinc oxide separation of iron Add zinc oxide suspension (3.15) about 5 mL at a time, mixing thoroughly after each addit
31、ion, until the solution is neutralized and a faint permanent precipitate of iron-group hydroxides is obtained; then make a final addition of 10 mL of zinc oxide suspension (3.15) to complete the precipitation. It is indicated by a definite change from a clear dark-coloured solution to a turbid brown
32、 solution due to the precipitation of hydroxides. The addition of 10 mL excess of zinc oxide suspension (3.15) causes the brown precipitate to appear lighter in colour and the supernatant liquid to assume a slightly milky white appearance. Transfer to a 500 mL volumetric flask and dilute to the mark
33、. Pour into a dry 650 mL conical beaker, mix and allow to stand for 5 min. Filter through a dry medium fast texture 24 cm fluted filter paper into a 250 mL volumetric flask. NOTEWhatman No. 12 or equivalent is suitable. Rinse the flask with the first few mL of the filtrate, and then collect a 250 mL
34、 aliquot. Transfer the aliquot to a 650 mL conical beaker. 6.3.4 Separation of cobalt Add 10 mL of hydrochloric acid (3.3) and 1 mL of iron(III) chloride solution (3.5) and heat to boiling. Remove from the source of heat, add 15 mL of 1-nitroso-2-naphthol solution (3.8), stir in a little paper-pulp
35、and allow to stand for at least 3 h, but preferably overnight. Filter through a paper-pulp pad, wash the pad and precipitate three times with hydrochloric acid (3.4), and then three times with cold water. Transfer the filter and precipitate to a platinum dish. Ignite at a low temperature until freed
36、 from carbonaceous matter and finally at a temperature not exceeding 800 C. Dissolve the residue in 10 mL of hydrochloric acid (3.3), add 5 mL of phosphoric-sulfuric acid (3.11), and evaporate to fuming. Cool, dissolve in 5 mL of water, transfer to a 25 mL volumetric flask, dilute to the mark and mi
37、x. 6.3.5 Development of the colour Transfer two 10 mL aliquots of the solution into separate 50 mL volumetric flasks. Make this transfer and all subsequent reagent additions by means of a safety pipette or burette. To the first aliquot add 10 mL nitroso-R-salt solution (3.9) and mix. Add 10 mL of so
38、dium acetate solution (3.12), mix and allow to stand for 5 min at room temperature. Add 10 mL of nitric acid (3.7) mix, dilute to the mark and mix. Allow to stand for a further 5 min at room temperature. 6.3.6 Compensating solution To the second aliquot add 10 ml of sodium acetate solution (3.12), 1
39、0 mL of nitric acid (3.7), dilute to the mark and mix. 6.3.7 Spectrophotometric measurement Measure the absorbance of the test portion and blank solution at a wavelength of 525 nm, and at 20 1 C, using cells of 2 cm or 4 cm optical path length in accordance with the cobalt content and calibration gr
40、aph described in 6.4. Record the absorbance readings. 6.4 Preparation of the calibration graph To a series of 250 mL conical beakers add 1 mL of iron(III) chloride solution (3.5) and 5 mL of phosphoric-sulfuric acid mixture (3.11). Make additions of the standard cobalt solution (3.2) as given in Tab
41、le 1, and according to the concentration of cobalt expected. Licensed Copy: sheffieldun sheffieldun, na, Wed Dec 06 15:04:02 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6200-3.11.2:1991 BSI 09-19993 Table 1 Calibration data for optical path lengths, additions of cobalt solution (3.2) and equivalen
42、t cobalt percentage by mass Evaporate to fuming. Cool, dissolve in 5 mL of water, transfer to a 25 mL volumetric flask, dilute to the mark and mix. Treat the calibration solutions exactly as described in 6.3.5 to 6.3.7. Prepare calibration graphs by plotting the differences of the absorbance reading
43、s of the cobalt standard solutions and the zero cobalt solution against the equivalent cobalt percentage by mass. 7 Calculation and expression of results 7.1 Calculation From the difference in absorbance of the test solution and its compensating solution, read the cobalt percentage by mass from the
44、calibration graph corresponding to the optical path length of the cell used. If necessary, subtract a cobalt blank correction determined from the absorbance readings obtained from the blank solution and its compensating solution. 7.2 Precision 7.2.1 Precision data Planned trials of this method were
45、carried out by nine to 11 analysts, each from a different laboratory and using 11 steels. The mean results for each laboratory given in the original report1), have been examined statistically to obtain values for between- laboratory standard deviation Sb. In the absence of individual results it is n
46、ot possible to calculate repeatability r, and reproducibility R, as defined in BS 5497-1:1987. From the results reported, the statistical limits (2.83Sb) for probability P = 95 %, for agreement between laboratory means have been calculated, and are given in Table 2. The difference between the mean r
47、esults of two laboratories found on identical test material will exceed the 95 % probability level not more than once in 20 cases, on average, in the normal and correct operation of the method. Table 2 Precision data from steels and irons 4 cm cell2 cm cell Cobalt solution Cobalt equivalent Cobalt s
48、olution Cobalt equivalent mL% (m/m)mL% (m/m) 0.0nil0.0nil 2.50.00512.50.025 5.00.01015.00.030 7.50.01517.50.035 10.00.02020.00.040 22.50.045 1) Methods of Analysis Committee. The absorptiometric determination of trace amounts of cobalt in iron and steel and some associated materials. Journal of the
49、Iron and Steel Institute, March 1959, 191, 236-240. Alloy type: elementCobalt content Inter-laboratory agreement 2.83Sb CSiMnCrVMoNiCu % (m/m)% (m/m)% (m/m)% (m/m)% (m/m)% (m/m)% (m/m)% (m/m)% (m/m) 0.00020.00040.00020.0001 0.001 18.08.00.00300.00142 0.020.43 0.01 0.02 0.02 0.020.00330.00074 0.340.01150.00139 0.230.300.470.04 0.0050.190.010.010.01250.00184 0.350.320.501.010.211.490.01700.00314 0.040.60.7521.00.240.02650.00200 0.190.190.480.100.05 0.010.180.120.02660.00303 0.150.190.480.080.040.040.030.060.02070