1、BRITISH STANDARD BS 6200-3.12.1: 1986 Sampling and analysis of iron, steel and other ferrous metals Part 3: Methods of analysis Section 3.12 Determination of copper Subsection 3.12.1 Steel and cast iron: volumetric method UDC 669.1:543.24:546.56BS6200-3.12.1:1986 This British Standard, having been p
2、repared under the directionof the Iron and Steel Standards Committee, was published under the authority ofthe Board of BSI and comes intoeffect on 30 September 1986 BSI 09-1999 The following BSI references relate to the work on this standard: Committee reference ISM/18 Draft for comment 85/36502 DC
3、ISBN 0 580 15279 0 Foreword This Subsection of BS6200 has been prepared under the direction of the Iron and Steel Standards Committee. It supersedes method 1 for the determination of copper in BSI Handbook No.19, to which it is technically equivalent. BS 6200 is a multipart British Standard covering
4、 all aspects 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
5、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 front cover, pagesi andii, pages1 and2, an inside back cover and a back cover. This
6、 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. Amendments issued since publication Amd. No. Date of issue CommentsBS6200-3.12.1:1986 BSI 09-1999 i Contents Page Foreword Inside front c
7、over 1 Scope 1 2 Principle 1 3 Reagents 1 4 Apparatus 1 5 Sampling 1 6 Procedure 2 7 Calculation and expression of results 2 8 Test report 2 Publications referred to Inside back coverii blankBS6200-3.12.1:1986 BSI 09-1999 1 1 Scope This Subsection of BS6200 describes a volumetric method for the dete
8、rmination of copper in steel and cast iron. The method is applicable to copper contents exceeding0.1%m/m. NOTEThe titles of the publications referred to in this Subsection on BS6200 are listed on the inside back cover. 2 Principle In an oxidized hydrochloric acid solution of the sample, iron is redu
9、ced by boiling with sulphurous acid. Copper is precipitated as cuprous thiocyanate from a neutralized solution made slightly acid with sulphuric acid. The precipitate is filtered off, washed and dissolved in acid. The determination is completed volumetrically by releasing the iodine equivalent of th
10、e copper with potassium iodide and titrating with sodium thiosulphate. 3 Reagents During the analysis, use only reagents of recognized analytical reagent grade and only distilled water or water of equivalent purity, free from copper. 3.1 Acetic acid, glacial, density ( ) 1.048g/mL to1.050g/mL. 3.2 A
11、mmonia solution, 0.91g/mL, diluted1+1. 3.3 Copper, standard solution, corresponding to 1 mg of copper per mL. Dissolve 1.000 g of high purity copper in30mL of nitric acid (3.6). Boil to remove nitrous fumes and cool. Transfer to a1L volumetric flask, dilute to the mark and mix. 3.4 Hydrochloric acid
12、, 1.16g/mL to1.19g/mL. 3.5 Nitric acid, 1.42g/mL. 3.6 Nitric acid, 1.42g/mL, diluted2 +3. 3.7 Potassium iodide, 600 g/L solution. Dissolve 60g of potassium iodide in water, dilute to100mL and mix. 3.8 Potassium thiocyanate, 200 g/L solution. Dissolve 200g of potassium thiocyanate in water, dilute to
13、1L and mix. 3.9 Sodium fluoride 3.10 Sodium sulphite, 250 g/L solution. Dissolve 250 g of sodium sulphite in water, dilute to1L and mix. 3.11 Sodium sulphite-acid wash To 1 L of sulphuric acid (3.15) add10mL of sodium sulphite solution (3.10), 5mL of potassium thiocyanate solution (3.8) and mix. 3.1
14、2 Sodium thiosulphate, 4 g/L solution, corresponding to1mg of copper per mL. 3.12.1 Preparation. Dissolve 4 g of sodium thiosulphate pentahydrate (Na 2 S 2 O 3 .5H 2 O) in water containing0.1g of sodium carbonate. Transfer to a1L volumetric flask, dilute to the mark and mix. 3.12.2 Standardization.
15、Transfer25mL of copper solution (3.3) to a250mL conical beaker. Add10mL of sulphuric acid (3.15) and evaporate to fuming. Cool, add with care10mL of water,0.5g of sodium fluoride (3.9) and, when dissolved, add ammonia solution (3.2) until the blue colour of the cuprammonium complex is fully develope
16、d. Cool, acidify with glacial acetic acid (3.1) and add1mL excess. Cool, add 5mL of potassium iodide solution (3.7) and titrate with sodium thiosulphate solution (3.12) until the brown iodine colour is almost discharged. Add5mL of starch indicator (3.13), 10mL of potassium thiocyanate solution (3.8)
17、 and continue the titration until the blue starch-iodine colour is just discharged. Record the copper equivalent of the sodium thiosulphate solution in mg per mL. 3.13 Starch, 5 g/L solution. Make a suspension of 0.5g of starch in10mL of water. Add to90mL of boiling water. Cool, dilute to100mL and m
18、ix. 3.14 Sulphuric acid, 1.84g/mL. 3.15 Sulphuric acid, 1.84g/mL, diluted 3 +17. To 400 mL of water add cautiously150mL of sulphuric acid (3.14). Mix, cool, dilute to1L and mix. 3.16 Sulphuric acid, 1.84g/mL, diluted 1 +99. To 400 mL of water add cautiously10mL of sulphuric acid (3.14). Mix, cool, d
19、ilute to1L and mix. 3.17 Sulphurous acid Pass sulphur dioxide gas into1L of water until a saturated solution is obtained. 4 Apparatus Use ordinary laboratory apparatus. Use only volumetric glassware in accordance with class A of BS846, BS1583 or BS1792, as appropriate. 5 Sampling Sampling shall be c
20、arried out in accordance with BS1837.BS6200-3.12.1:1986 2 BSI 09-1999 NOTEBS 6200-2 “Methods of sampling and sample preparation”, which will supersede BS1837, is currently in preparation. On its publication, this Subsection will be amended to include a requirement to sample in accordance with BS6200
21、-2. 6 Procedure 6.1 Test portion Weigh, to the nearest 0.001g, a test portion in accordance with the following: a) 5 g for samples with presumed copper contents up to0.25% m/m; b) 2 g for samples with presumed copper contents between0.25% m/m and1%m/m; c) 1 g for samples with presumed copper content
22、s between1%m/m and5% m/m; d) 0.5 g for samples with presumed copper contents exceeding5% m/m. 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 in a650mL c
23、onical beaker, add50mL of hydrochloric acid (3.4), cover the beaker and heat until solvent action ceases. For steels which do not dissolve readily in hydrochloric acid, add10mL of nitric acid (3.5). Oxidize with nitric acid (3.5), evaporate to dryness, cool and add30mL of hydrochloric acid (3.4). He
24、at until the salts are dissolved and evaporate to20mL. Add100mL of hot water,100mL of the sulphurous acid (3.17), heat to boiling and filter through a paper-pulp pad into a650mL conical beaker. If tungsten, niobium or titanium is present, allow the solution to stand for1h before filtering. Wash the
25、filter and precipitate with sulphuric acid (3.16). Heat the filtrate to70 C and add ammonia solution(3.2) until a faint permanent precipitate is obtained. Dissolve the precipitate in a minimum amount of sulphuric acid (3.15) and add5mL excess. Add40mL of sodium sulphite solution(3.10), 10mL of potas
26、sium thiocyanate solution (3.8), heat to boiling and boil for2min. Cool to room temperature and filter through a paper-pulp pad, washing with the sodium sulphite-acid wash solution (3.11). For copper contents below0.1% m/m, allow the solution to stand overnight before filtering. Dissolve the precipi
27、tate from the filter into a250mL conical beaker with40mL of nitric acid (3.6), and wash the filter with hot water. NOTE 1It is essential that this operation is carried out under a good fume-extraction hood. Add 10 mL of sulphuric acid (3.15) and evaporate to fuming. Cool, add10mL of water,0.5g of so
28、dium fluoride (3.9) and, when dissolved, add ammonia solution (3.2) until the blue colour of the cuprammonium complex is fully developed. Cool, acidify with glacial acetic acid (3.1) and add1mL excess. NOTE 2No colour will develop in the blank test: changes in acidity should be detected by removing
29、a drop of solution and testing it with litmus paper. Cool, add 5 mL of potassium iodide solution (3.7) and titrate with sodium thiosulphate solution (3.12) until the brown iodine colour is almost discharged. Add5mL of starch indicator (3.13), 10mL of potassium thiocyanate solution (3.8) and continue
30、 the titration until the blue starch-iodide colour is just discharged. 7 Calculation and expression of results 7.1 Calculation Calculate the copper content, expressed as a percentage by mass, from the equation where 7.2 Precision Replicate agreements in accordance with the following may be expected
31、from this method: a) 0.01% for copper contents of0.1% m/m; b) 0.05% for copper contents of5% m/m. 8 Test report The test report shall contain the following information: a) identification of the sample; b) the method of analysis used, by reference to this Subsection of BS6200; c) the results obtained
32、 and the form in which they are expressed; d) any particular details noted during the determination; e) any operation not specified in this standard, or any optional operations which may have influenced the results. V is the volume (in mL) of sodium thiosulphate solution (3.12) required for the test
33、 portion; V 0 is the volume (in mL) of sodium thiosulphate solution (3.12) required for the blank test (6.2); m 1 is the copper equivalent (in mg/mL) of the sodium thiosulphate solution (3.10.2); m is the mass (in g) of the test portion (6.1). Copper content V ( V 0 ) m 1 10m - =BS6200-3.12.1:1986 B
34、SI 09-1999 Publications 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 alloys and ferro-alloys. BSI Handbook No. 19, Methods for th
35、e sampling and analysis of iron, steel and other ferrous metals 1) . 1) Referred to in the foreword only.BS 6200-3.12.1: 1986 BSI 389 Chiswick High Road London W4 4AL BSIBritishStandardsInstitution BSI is the independent national body responsible for preparing BritishStandards. It presents the UK vi
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