1、BRITISH STANDARD BS 6200-3.12.4: 1986 Sampling and analysis of iron, steel and other ferrous metals Part 3: Methods of analysis Section 3.12 Determination of copper Subsection 3.12.4 Cast iron: volumetric method UDC 669.1:543.24:546.56BS6200-3.12.4:1986 This British Standard, having been prepared un
2、der the directionof the Iron and Steel Standards Committee, was published under the authority ofthe Board of BSI and comes intoeffect on September1986 BSI 09-1999 The following BSI references relate to the work on this standard: Committee reference ISM/18 Draft for comment85/36503 DC ISBN 0 580 1528
3、0 4 Foreword This Subsection of BS6200 has been prepared under the direction of the Iron andSteel Standards Committee. It supersedes method5 for the determination ofcopper in BSI Handbook No.19, to which it is technically equivalent. BS 6200 is a multipart British Standard covering all aspects of th
4、e 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 Standards are res
5、ponsible 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 standard has been
6、 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 CommentsBS6200-3.12.4:1986 BSI 09-1999 i Contents Page Foreword Inside front cover 1 Scope 1 2 P
7、rinciple 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 Precision data 3 Publications referred to Inside back coverii blankBS6200-3.12.4:1986 BSI 09-1999 1 1 Scope This Subsection of BS6200 describes a volumetric method for t
8、he determination of copper in cast iron. The method is applicable to copper contents exceeding0.1% m/m. NOTEThe titles of the publications referred to in this Subsection of BS6200 are listed on the inside back cover. 2 Principle After the removal of iron by extraction with isobutylacetate, copper is
9、 converted to itsdiethyldithiocarbamate complex in ammoniacalcitrate solution containing ethylenediaminetetra-acetic acid disodium salt (EDTA Na 2 ). It is then extracted into chloroform. Organic matter is destroyed and copper is titrated with EDTA Na 2 . 3 Reagents During the analysis, use only rea
10、gents of recognized analytical reagent grade and only distilled water or water of equivalent purity, free from copper. 3.1 Ammonia solution, density ( )0.91g/mL. 3.2 Ammonia solution, 0.91g/mL, diluted1+1. 3.3 Triammonium citrate, 500g/L solution. Dissolve 500g of citric acid (H 8 C 6 O 7 .H 2 O) in
11、500mL of ammonia solution (3.1). Cool, dilute to1L and mix. 3.4 Chloroform 3.5 Copper, standard solution, corresponding to1mg copper permL. Dissolve 1.000g of high purity copper in30mL of nitric acid (3.12). Boil to remove nitrous fumes and cool. Transfer to a1L volumetric flask, dilute to the mark
12、and mix. 3.6 Ethylenediaminetetra-acetic acid disodium salt (EDTA Na 2 ). 3.7 Ethylenediaminetetra-acetic acid disodium saltstandard solution, corresponding to approximately1mg of copper permL. 3.7.1 Preparation. Dissolve5.86g of EDTA Na 2in water. Transfer to a1L volumetric flask, dilute to the mar
13、k and mix. 3.7.2 Standardization. Transfer10.0mL of copper solution (3.5) to a400mL conical beaker and add1mL of perchloric acid (3.13). Evaporate just to fumes of perchloric acid, cool and dissolve in50mL of water. Add 1 mL murexide indicator (3.10) followed by ammonia solution (3.2) dropwise until
14、 the pH of the solution, as indicated by close-range indicator paper, is between7 and9. Titrate with EDTA Na 2standard solution (3.7.1) to a purple end-point, which does not change on further addition of EDTA Na 2standard solution. Record the copper equivalent of the EDTA Na 2standard solution in mg
15、 permL. 3.8 Hydrochloric acid, 1.16g/mL to1.19g/mL. 3.9 Isobutyl acetate 3.10 Murexide, 0.5g/L solution in ethanediol. Dissolve0.05g of murexide in100mL of ethanediol. 3.11 Nitric acid, 1.42g/mL. 3.12 Nitric acid, 1.42g/mL, diluted2+3. 3.13 Perchloric acid, 1.54g/mL. 3.14 Sodium diethyldithiocarbama
16、te, 100g/L solution. Dissolve10g of sodium diethyldithiocarbamate in water, dilute to100mL and mix. 4 Apparatus Use ordinary laboratory apparatus. Use only volumetric glassware in accordance withclass A of BS846, BS1583 or BS1792, as appropriate. 5 Sampling Sampling shall be carried out in accordanc
17、e 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 amended to include a requirement to sample in accordance with BS6200-2. 6 Procedure 6.1 Test portion Weigh, to the nearest0.
18、001g, a test portion in accordance with the following: a) 5 g, for samples with presumed copper contents up to0.5% m/m; b) 2 g, for samples with presumed copper contents between0.5% m/m and1.0% m/m; c) 1 g, for samples with presumed copper contents above1% m/m.BS6200-3.12.4:1986 2 BSI 09-1999 6.2 Bl
19、ank 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 a dry400mL squat beaker and, depending on its mass, add a mixture of hydrochloric acid (3.8) and nitric acid
20、 (3.11) in accordance with the following: a) for a 5 g test portion,50mL of hydrochloric acid and15mL nitric acid; b) for a 2 g test portion,35mL of hydrochloric acid and10mL nitric acid; c) for a 1 g test portion,20mL of hydrochloric acid and10mL nitric acid. Add the premixed acids in small portion
21、s (about10mL at a time), waiting until the vigorous reaction subsides before adding the next portion and covering the beaker after each addition. Do not apply heat. NOTE 1Most cast irons will dissolve readily without the application of heat, and usually any apparent drillings remaining5min after the
22、 addition of acid are pseudomorphs of graphite and silica. A gentle effervescence is not evidence that the sample is still dissolving, but is more likely to be due to the oxidation of hydrochloric acid by nitric acid. For alloy irons, in particular high chromium irons, heating may be necessary. This
23、 should be kept to a minimum and prolonged boiling avoided as this leads to loss of hydrochloric acid and decreased efficiency of the isobutyl acetate extraction. When the test portion has dissolved, cool and then filter through a glass filter or dry glass wool pad into a dry250mL conical separating
24、 funnel; wash the beaker and the filter with hydrochloric acid (3.8) from a polyethylene wash bottle. For a 5 g test portion, adjust the volume to about90mL with hydrochloric acid (3.8) and add150mL of isobutyl acetate (3.9). For a2g test portion, adjust the volume to about75mL and add100mL of isobu
25、tyl acetate (3.9). For a1g test portion, adjust the volume to about60mL and add60mL of isobutyl acetate (3.9). Shake vigorously for30s, allow the two layers to separate and run the lower (aqueous) layer into a400mL squat beaker. Add10mL of hydrochloric acid (3.8) to the isobutyl acetate in the separ
26、ating funnel, shake again and transfer the lower (aqueous) layer to the400mL beaker. Repeat this procedure with two further10mL portions of hydrochloric acid (3.8). Allow the separating funnel to stand for2min, then run into the beaker the small amount of acid which has drained down, allowing the in
27、terface to travel to the bottom of the stopcock bore. Rinse the stem of the separating funnel with water into the beaker. Discard the organic phase. Evaporate the solution to about40mL, add5mL of nitric acid (3.11) and10mL of perchloric acid (3.13) and then evaporate to fumes of perchloric acid. Con
28、tinue fuming for3min with the beaker covered. Cool slightly, add35mL of water and heat to boiling, then cool. If the sample contains more than2.5% m/m of copper, transfer to a100mL volumetric flask, dilute to the mark and mix. Take an aliquot containing not more than25mg of copper, dilute if necessa
29、ry to a volume of about50mL and continue as follows, in common with all other test portions. Add 15 mL of the triammonium citrate solution(3.3),2g of EDTA Na 2(3.6), followed by ammonia solution (3.1) dropwise until the solution is alkaline to litmus paper. Then add5mL in excess. Filter through a pa
30、per-pulp pad into a250mL conical separating funnel and washwithcold water. Add10mL of sodium diethyldithiocarbamate solution (3.14) and25mL of chloroform (3.4). Shake vigorously, allow the two layers to separate and run the lower (chloroform) layer into a400mL conical beaker. Add10mL of chloroform (
31、3.4) to the separating funnel and shake again, running the chloroform layer into the conical beaker. Wash with two further10mL portions of chloroform (3.4) and combine all the chloroform extracts. Discard the aqueous phase. Evaporate the chloroform phase just to dryness. Add cautiously5mL of nitric
32、acid (3.11), followed by10mL of hydrochloric acid (3.8) and1mL of perchloric acid (3.13). NOTE 2This and all subsequent reagent additions should be made by means of a pipette or burette. Evaporate to fumes of perchloric acid, cool and dissolve in50mL of water. Add1mL of murexide indicator (3.10) fol
33、lowed by ammonia solution (3.2) dropwise until the pH of the solution, as indicated by suitable close-range indicator paper, is between7 and9. Titrate with EDTA Na 2standard solution (3.7) to a purple endpoint which does not change on further addition of EDTA Na 2standard solution (3.7).BS6200-3.12.
34、4:1986 BSI 09-1999 3 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 A planned trial of this method was carried out by10analysts, each from a different laboratory: three tests were carried
35、out by each analyst on each of four samples. From the results obtained, the95% confidence limits (2s) have been calculated in accordance with BS5497-1 and are given inTable 1. Table 1 Precision data The difference between two single results found on identical material by one analyst using the same a
36、pparatus 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 different laboratories on identical test material will
37、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 analysis used, by reference to this Subsection of BS620
38、0; 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. V is the volume (in mL) of EDTA Na 2standard solution (3.7
39、) used; V 0 is the volume (in mL) of EDTA Na 2standard solution required for the blank test (6.2); m 1 is the copper equivalent (in mg/mL) of the EDTA Na 2standard solution (3.7.2); m is the mass (in g) of the test portion (6.1). Alloy type Copper content Repeatability, r Reproducibility, R % m/m Wh
40、ite cast iron 0.13 0.008 0.014 Grey cast iron 0.49 0.019 0.040 Grey cast iron 1.47 0.029 0.086 13% m/m Ni, 4% m/m Cr austenitic cast iron 5.03 0.038 0.122 Copper content VV 0 () m 1 10m - =4 blankBS6200-3.12.4:1986 BSI 09-1999 Publications referred to BS 846, Specification for burettes. BS 1583, Spe
41、cification 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. BS 5497, Precision of test methods. BS 5497-1, Guide for the determination of repeatability and reproducibility for a s
42、tandard test method. BSI Handbook No. 19, Methods for the sampling and analysis of iron, steel and other ferrous metals 1) . 1) Referred to in the foreword only.BS 6200-3.12.4: 1986 BSI 389 Chiswick High Road London W4 4AL BSIBritishStandardsInstitution BSI is the independent national body responsib
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