1、BRITISH STANDARD BS 6200-3.29.1: 1986 Sampling and analysis of iron, steel and other ferrous metals Part 3: Methods of analysis Section3.29 Determination of tantalum Subsection3.29.1 Steel: spectrophotometric method UDC 669.1:543.42.062:546.883BS6200-3.29.1:1986 This British Standard, having been pr
2、epared under the directionof the Iron and SteelStandards Committee, waspublished under the authorityof the Board of BSI andcomes into effect on September1986 BSI 09-1999 The following BSI references relate to the work on this standard: Committee reference ISM/18 Draft for comment85/36494 DC ISBN 0 5
3、80 15282 0 Foreword This Subsection of BS6200 has been prepared under the direction of the Iron and Steel Standards Committee. It supersedes method1 for the determination of tantalum in BSI Handbook No.19, to which it is technically equivalent. BS6200 is a multipart British Standard covering all asp
4、ects of the sampling and analysis of iron, steel and other ferrous metals. A list of contents, together with general information, will be given in Part1, to be published in due course. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standar
5、ds 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, pagesi andii, pages1 to4, an inside back cover and a back cover. This standar
6、d 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. Amendments issued since publication Amd. No. Date of issue CommentsBS6200-3.29.1:1986 BSI 09-1999 i Contents Page Foreword ii 1 Scope 1 2 Princip
7、le 1 3 Reagents 1 4 Apparatus 1 5 Sampling 1 6 Procedure 2 7 Calculation and expression of results 3 8 Test report 3 Table 1 Precision data 3 Publications referred to Inside back coverii blankBS6200-3.29.1:1986 BSI 09-1999 1 1 Scope This Subsection of BS6200 describes a spectrophotometric method for
8、 the determination of lead in steel. The method is applicable to lead contents from0.0005% m/m to0.05% m/m. NOTEThe titles of the publications referred to in this Subsection of BS6200 are listed on the inside back cover. 2 Principle Tantalum is precipitated with phenylarsonic acid using zirconium an
9、d niobium as carriers. It is then separated from interfering elements by extraction into4-methylpentan-2-one. Tantalum is converted to its pyrogallol complex and the determination is completed spectrophotometrically. 3 Reagents During the analysis use only reagents of recognized analytical reagent g
10、rade and only distilled water or water of equivalent purity. 3.1 Ammonium oxalate,40g/L solution. Dissolve40g of ammonium oxalate (COONH 4 ) 2 .H 2 O in hot water, cool, dilute to1L and mix. 3.2 Boric acid, saturated. Shake20g of boric acid with100mL of water. 3.3 Hydrochloric acid, density ( )1.16g
11、/mL to1.19g/mL. 3.4 Hydrochloric acid, 1.16g/mL to1.19g/mL, diluted1+4. 3.5 Hydrochloric acid, 1.16g/mL to1.19g/mL, diluted1+9. 3.6 Hydrochloric acid, 1.16g/mL to1.19g/mL, diluted1+19. 3.7 Hydrofluoric acid,40%m/m. 3.8 Hydrofluoric acid,40%m/m, diluted1+4. Use only polyethylene apparatus for measuri
12、ng and storing. 3.9 Hydrogen peroxide,30%m/m. 3.10 Iron, of high purity, free from tantalum. 3.11 4-methylpentan-2-one (isobutylmethylketone). 3.12 Niobium metal powder, of high purity, less than0.05%m/m tantalum. 3.13 Oxalic acid,80g/L solution. Dissolve80g of oxalic acid (COOH) 2 .2H 2 O in warm w
13、ater, cool, dilute to1L and mix. 3.14 Phenylarsonic acid 3.15 Phenylarsonic acid wash Dissolve0.5g of phenylarsonic acid(3.14) and1g of ammonium nitrate in hot water. Dilute to1L and mix. 3.16 Orthophosphoric acid, 1.75g/mL, diluted1+3. 3.17 Potassium hydrogen sulphate, (KHSO 4 ). 3.18 Pyrogallol,35
14、0g/L solution. Dissolve35g of pyrogallol in about60mL of warm sulphuric acid(3.21). Cool and make up to100mL with sulphuric acid(3.21). 3.19 Sulphuric acid, 1.84g/mL. 3.20 Sulphuric acid, 1.84g/mL, diluted1+4. To400mL of water cautiously add200mL of sulphuric acid(3.19). Mix, cool, dilute to1L and m
15、ix. 3.21 Sulphuric acid, 1.84g/mL, diluted1+49. To80mL of water cautiously add2mL of sulphuric acid(3.19). Cool, dilute to100mL and mix. 3.22 Tantalum, standard solution corresponding to0.1mg tantalum per mL. Fuse5g of potassium hydrogen sulphate(3.17) in a platinum vessel. Allow the melt to solidif
16、y and cool. Weigh0.1221g of high purity tantalum pentoxide and transfer to the vessel containing the fused solid. Fuse over a burner, cool and extract the melt with ammonium oxalate solution(3.1). Transfer to a1L volumetric flask, dilute to the mark with ammonium oxalate solution(3.1) and mix. 3.23
17、Zirconyl nitrate,3g/L solution. Dissolve0.3g of zirconyl nitrate in50mL of hydrochloric acid(3.4). Dilute to100mL and mix. 4 Apparatus Use ordinary laboratory apparatus. Use only volumetric glassware in accordance with class A of BS846, BS1583 or BS1792, as appropriate. Use also the following. 4.1 S
18、pectrophotometer 4.2 Cells, having an optical path length of4cm. 5 Sampling Sampling shall be carried out in accordance with BS1837. NOTEBS6200-2 “Methods of sampling and sample preparation”, which will supersede BS1837, is currently in preparation. On its publication, this Subsection will be amende
19、d to include a requirement to sample in accordance with BS6200-2.BS6200-3.29.1:1986 2 BSI 09-1999 6 Procedure 6.1 Test portion Weigh, to the nearest0.001g, a test portion of10g. NOTEWhen the tantalum content exceeds0.005%m/m, the sample mass should be reduced proportionately and the test portion mad
20、e up to10g with high purity iron(3.10). 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 the reagents. 6.3 Determination Place the test portion and5mg of high purity niobium metal powder(3.12) in an800mL squat
21、 beaker. Add50mL of hydrochloric acid(3.3), cover the beaker and heat. If necessary, add more of the hydrochloric acid in small increments until solvent action ceases. Oxidize cautiously with15mL of hydrogen peroxide(3.9). Dilute to about100mL with cold water and filter through a paper-pulp pad into
22、 an800mL tall-form beaker. Remove any particles adhering to the beaker with a rubber-tipped glass rod and wash the beaker and filter with hot hydrochloric acid(3.6). Reserve the filtrate. Transfer the filter to a platinum vessel, dry and ignite at a low temperature until carbonaceous matter is remov
23、ed. Then ignite at800 C. Cool. Add a few drops of oxalic acid solution(3.13) and1mL of hydrofluoric acid(3.7) and evaporate to dryness. Then ignite at a low temperature and finally at800 C. Cool. Fuse the residue with2g of potassium hydrogen sulphate(3.17), extract the melt with10mL of sulphuric aci
24、d(3.20) and add the extract to the reserved filtrate. Add5mL zirconyl nitrate solution(3.23). Dilute to500mL with hot water, heat to boiling and then add1g of phenylarsonic acid(3.14), freshly dissolved in about20mL of hot water. Stir and add a little paper pulp. Heat to boiling and simmer for about
25、5min. Allow to stand at about90 C for1h. Filter through a paper-pulp pad and wash six times with hot phenylarsonic acid wash solution(3.15). Dry the filter in a porcelain dish and ignite at a temperature not exceeding700 C. NOTE 1Platinum dishes should not be used for the ignition as they are readil
26、y attacked by the arsenical compound. Cool, transfer the residue to a platinum vessel, moisten with a few drops of water, dissolve the oxides with about5mL of hydrofluoric acid(3.7) and evaporate to dryness. Redissolve by warming gently with5mL of hydrofluoric acid(3.8), then cool. Pour the solution
27、 into a50mL separating funnel containing1mL of boric acid solution(3.2). NOTE 2The use of a plastic funnel for this addition will prevent any possibility of hydrofluoric acid attack on the neck of the separating funnel. Rinse the vessel with5mL of hydrochloric acid(3.5) and add to the separating fun
28、nel. Add10mL of4-methyl-pentan-2-one(3.11) and shake for30s. Allow the phases to separate, then run off the lower (aqueous) layer into a second separating funnel containing1mL of boric acid solution(3.2), retaining the organic layer in the first separating funnel. Add5mL of4-methylpentan-2-one(3.11)
29、 to the second separating funnel and shake for30s. Discard the lower (aqueous) layer, then combine the two organic extracts. Add1mL of boric acid solution(3.2),5mL of hydrofluoric acid(3.8) and5mL of hydrochloric acid(3.5); shake and allow the phases to separate. Discard the lower (aqueous) layer an
30、d pour the organic extract into a50mL platinum vessel. Rinse the separating funnel with a little4-methylpentan-2-one(3.11) and add to the platinum vessel. Cautiously evaporate to dryness under an infra-red lamp, in a current of air if possible. Heat gradually up to800 C and maintain at this temperat
31、ure for a few minute. Fuse the residue with2g of potassium hydrogen sulphate(3.17), extract with25mL of ammonium oxalate solution(3.1) into a100mL conical beaker and cool. Add2mL phosphoric acid(3.16) and20mL of pyrogallol solution(3.18). Transfer to a50mL volumetric flask, dilute to the mark with a
32、mmonium oxalate solution(3.1) and mix. Adjust the temperature to23 1 C and maintain for20min. NOTE 3Any other temperature between20 C and30 C is permissible provided that it can be controlled within 1 C and that the same temperature is used for the calibration. Set the spectrophotometer(4.1) to zero
33、 absorbance in relation to water. Measure the absorbance of the test solution and blank solution at a wavelength of400nm, using4cm cells(4.2). Convert the readings obtained to milligrams of tantalum by reference to the calibration graph(6.4).BS6200-3.29.1:1986 BSI 09-1999 3 6.4 Preparation of the ca
34、libration graph To a series of six50mL platinum vessels add0.0,1.0,2.0,3.0,4.0, and5.0mL of tantalum standard solution(3.22), corresponding to0,0.1,0.2,0.3,0.4 and0.5mg tantalum respectively. Evaporate to dryness. Finally, heat at800 C and reserve. Place10.0g portions of high purity iron(3.10) into
35、a series of six800mL squat beakers and add5mg portions of high purity niobium metal powder(3.12) to each. Continue in accordance with6.3, but in each case use the reserved platinum vessel containing the evaporated tantalum aliquots for the ignition of the silica precipitates. Prepare the calibration
36、 graph by plotting absorbance readings against the equivalent mass of tantalum. 7 Calculation and expression of results 7.1 Calculation Calculate the tantalum content, expressed as a percentage by mass, from the equation Tantalum content= 7.2 Precision A planned trial of this method was carried out
37、by five analysts, each from a different laboratory; six tests were carried out by each analyst on each of six samples. From the results obtained, the95% confidence limits (2s) have been calculated in accordance with BS5497-1 and are given in Table 1. The difference between two single results found o
38、n identical material by one analyst using the same apparatus within a short time interval will exceed the repeatability, r, not more than once in20 cases in the normal and correct operation of the method. The difference between two single and independent results found by two operators working in dif
39、ferent 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. 8 Test report The test report shall contain the following information: a) identification of the sample; b) the method of ana
40、lysis used, by reference to this Subsection of BS6200; c) the results obtained and the form in which they are expressed; d) any particular details noted during the determination; e) any operations not specified in this standard or any optional operations which may have influenced the results. Table
41、1 Precision data where m 1 is the mass (in mg) of tantalum found in the test solution; m 0 is the mass (in mg) of tantalum found in the blank solution(6.2); m is the mass (in g) of the test portion(6.1). m 1 m 0 10m - Alloy type Tantalum content Repeatability, r Reproducibility, R Low carbon steel %
42、 m/m 0.0007 0.00014 0.00014 18%m/m Cr, 9%m/m Ni, 0.4%m/m Ti stainless steel 0.0017 0.00037 0.00042 Low carbon steel 0.0045 0.00045 0.00071 Low carbon steel 0.011 0.00141 0.00141 19%m/m Cr, 12%m/m Ni, 2.9%m/m Mo, 0.82%m/m Nb stainless steel 0.026 0.00266 0.00311 18%m/m Cr, 9%m/m Ni, 1%m/m Nb stain le
43、ss steel 0.048 0.00402 0.004524 blankBS6200-3.29.1:1986 BSI 09-1999 Publications referred to BS846, Specification for burettes. BS1583, Specification for one-mark pipettes. BS1792, Specification for one-mark volumetric flasks. BS1837, Methods for the sampling of iron, steel, permanent magnet alloys
44、and ferro-alloys. BS5497, Precision of test methods. BS5497-1, Guide for the determination of repeatability and reproducibility for a standard test method. BSI Hand book No.19 1) , Methods for the sampling and analysis of iron, steel and other ferrous metals. 1) Referred to in the foreword only.BS 6
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