BS 6200-3 1 1-1991 Sampling and analysis of iron steel and other ferrous metals - Methods of analysis - Determination of aluminium - Steel cast iron low carbon ferro-chromium and c.pdf

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1、BRITISH STANDARD BS6200-3.1.1: 1991 Sampling and analysis of iron, steel and other ferrous metals Part3: Methods of analysis Section3.1 Determination of aluminium Subsection3.1.1 Steel, cast iron, low carbon ferro-chromium and chromium metal: volumetric methodBS6200-3.1.1:1991 This British Standard,

2、 having been prepared under the directionof the Iron and SteelStandards Policy Committee, was published underthe authority of the Standards Board and comes into effect on 20 December1991 BSI10-1999 The following BSI references relate to the work on this standard: Committee reference ISM/18 Draft for

3、 comment91/38339DC ISBN 0 580 20227 5 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

4、Industry 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 CommentsBS6200-3.1.1:1991 BSI 10-1999 i Contents Page Committees responsible Inside front page Foreword

5、 ii 1 Scope 1 2 Principle 1 3 Reagents 1 4 Apparatus 2 5 Sampling 2 6 Procedure 2 7 Calculation and expression of results 5 8 Test report 5 Figure 1 Mercury cathode assembly 3 Table 1 Data for test portion, dissolution and electrolysis 2 Publication(s) referred to Inside back coverBS6200-3.1.1:1991

6、ii BSI 10-1999 Foreword This Subsection of BS6200 has been prepared under the direction of the Iron and Steel Standards Policy Committee and supersedes method1 for the determination of aluminium in BSI Handbook No.19, to which it is technically equivalent. BS6200 is a multipart British Standard, cov

7、ering 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 Part1. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for

8、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 to6, an inside back cover and a back cover. This standard has been updated (see

9、 copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover.BS6200-3.1.1:1991 BSI 10-1999 1 1 Scope This Subsection of BS6200 describes a volumetric method for the determination of aluminium in steel and cast iron and in grades o

10、f low carbon ferro-chromium and chromium metal which are soluble in dilute sulfuric acid. The method is applicable to the range of aluminium content normally found in these materials. NOTEThe titles of the publications referred to in this Subsection of BS6200 are listed on the inside back cover. 2 P

11、rinciple Major amounts of interfering elements are removed by mercury cathode electrolysis, followed by precipitation first with ammonia and then with cupferron. Any remaining traces of interfering elements are complexed in ammoniacal tartrate-cyanide solution, from which the aluminium is precipitat

12、ed with quinolin-8-ol. The determination is completed by titration of the quinolin-8-ol with potassium bromate and sodium thiosulfate. 3 Reagents During the analysis use only reagents of recognized analytical grade and only grade3 water as specified in BS3978. WARNING. Prepare reagents3.5, 3.6 and3.

13、7 in a fume cupboard. 3.1 Acetic acid, density =1.048g/mL to1.050g/mL. 3.2 Ammonia solution, =0.91g/mL. 3.3 Ammonia solution, =0.91g/mL, diluted1+1. 3.4 Ammonium chloride 3.5 Ammonium sulfide solution, =1.01g/mL. Pass a rapid stream of hydrogen sulfide gas from a generator or cylinder through1L of a

14、mmonia solution(3.3) until the density is1.01g/mL approximately. 3.6 Ammonium sulfide wash solution. Add5mL of ammonia solution(3.2) to950mL of water and pass hydrogen sulphide gas from a generator or cylinder until just acid to litmus paper. Add a further5mL of ammonia solution(3.2), dilute to1L an

15、d mix. 3.7 Bromine water, saturated solution. To100mL of water add5mL of bromine, shake and allow to stand until saturated. 3.8 Cupferron,50g/L solution. Dissolve5g of cupferron (also known as N-nitroso-N-phenylhydroxylamine, ammonium salt) in water, dilute to100mL and mix. The solid reagent and its

16、 solution deteriorate in storage; prepare this solution from fresh reagent immediately before use. 3.9 Cupferron-acid wash solution. To900mL of water add10mL of sulfuric acid(3.27) and5mL of cupferron solution(3.8), dilute to1L and mix. 3.10 Hydrochloric acid, =1.16g/mL to1.18g/mL. 3.11 Hydrochloric

17、 acid, =1.16g/mL to1.18g/mL, diluted1+1. 3.12 Hydrofluoric acid,40% (m/m). 3.13 Indigo carmine,10g/L solution. Dissolve1g of indigo carmine in50mL of water, filter, dilute to100mL and mix. 3.14 Iron(III) chloride,5g/L solution. Dissolve0.5g of high purity iron in20mL of hydrochloric acid(3.10), heat

18、 to boiling, oxidize with the minimum amount of nitric acid(3.17) and continue boiling to expel nitrous fumes. Cool, dilute to100mL and mix. 3.15 Mercury. Use clean mercury. Methods of recovering used mercury include filtration through a sintered glass funnel, and distillation of the remaining amalg

19、am in an iron or mild steel pot still in a fume cupboard 1) . 3.16 Methyl red,1g/L solution. Dissolve0.1g of methyl red in60mL of ethanol, dilute to100mL with water and mix. 3.17 Nitric acid, =1.42g/mL. 3.18 Potassium bromate, standard solution. Dissolve2.477g of potassium bromate (previously dried

20、to constant weight at105 C) and50g of potassium bromide(3.19) in water. Cool, transfer to a1L volumetric flask, dilute to the mark and mix.1mL of this solution is equivalent to0.2mg of aluminium. 3.19 Potassium bromide 3.20 Potassium cyanide,100g/L solution. Dissolve10g of potassium cyanide in water

21、, dilute to100mL and mix. 3.21 Potassium hydrogen sulfate 3.22 Potassium iodide,200g/L solution. Dissolve20g of potassium iodide in water, dilute to100mL and mix. 3.23 Quinolin-8-ol,50g/L solution. Dissolve5g of quinolin-8-ol (also known as8-hydroxyquinoline and oxine) in6mL of acetic acid(3.1), dil

22、ute to100mL and mix. 1) Methods of Analysis Committee. Mercury cathode electrolysis and its application to steel analysis. Journal of the Iron and Steel Institute 176, January1954,2936.BS6200-3.1.1:1991 2 BSI 10-1999 3.24 Sodium carbonate,150g/L solution. Dissolve150g of sodium carbonate in water, d

23、ilute to1L and mix. 3.25 Sodium thiosulfate, standard solution. Dissolve22g of sodium thiosulfate, 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.1mL of this solution is equivalent to approximately0.2mg of aluminium. 3

24、.26 Starch indicator,5g/L solution. Make a suspension of0.5g of starch in10mL of water. Pour into80mL of boiling water. Cool, dilute to100mL and mix. 3.27 Sulfuric acid, =1.84g/L. 3.28 Sulfuric acid, diluted1+9. To400mL of water, add cautiously100mL of sulfuric acid(3.27). Mix, cool, dilute to1L, an

25、d mix. 3.29 Sulfuric acid, diluted1+99. To400mL of water, add cautiously10mL of sulfuric acid(3.27). Mix, cool, dilute to1L and mix. 3.30 Tartaric acid,200g/L solution. Dissolve20g of tartaric acid in water, dilute to100mL and mix. 4 Apparatus 4.1 Ordinary laboratory apparatus 4.2 Volumetric glasswa

26、re, in accordance with classA of BS846, BS1583, or BS1792, as appropriate. 4.3 Mercury cathode cell. The mercury cathode cell shown in Figure 1 is recommended 2) , for a test portion of mass5g to10g. The capacity of the beaker can be varied to suit a test portion of any particular mass. The mass of

27、mercury shall be at least150times the mass of the test portion. 5 Sampling Carry out sampling in accordance with BS1837. NOTEBS6200-2, which will supersede BS1837, is currently in preparation. On its publication this Subsection will be amended to include sampling in accordance with BS6200-2. 6 Proce

28、dure 6.1 Test portion Weigh to the nearest0.001g, a test portion containing from1mg to10mg of aluminium. SeeTable 1 for the mass of test portion appropriate to the anticipated aluminium content. Table 1 Data for test portion, dissolution and electrolysis 6.2 Blank test In parallel with the determina

29、tion and following the same procedure carry out a blank test using the same quantities of all reagents. 6.3 Determination 6.3.1 Preparation of the test solution Place the test portion in a500mL squat beaker. Add12mL of sulfuric acid(3.28) for each1g of test portion (but16mL for each1g in the case of

30、 ferro-chromium or chromium) and40mL excess. (SeeTable 1.) Digest until solvent action ceases, and only a residue of carbides and insoluble non-metallic matter remains. Filter through a paper-pulp pad and wash with hot sulfuric acid(3.29). 6.3.2 Recovery of insoluble aluminium Transfer the pad and r

31、esidue to a platinum dish and ignite at a low temperature to remove carbonaceous matter. Cool, add0.5mL of sulfuric acid(3.28), and2mL of hydrofluoric acid(3.12). Heat gently to expel the acids, and re-ignite. Fuse the residue with a minimum amount of potassium hydrogen sulfate(3.21), cool, extract

32、the melt with water containing a few drops of sulfuric acid(3.27) and add to the filtrate. 2) Methods of Analysis Committee. Mercury cathode electrolysis and its application to steel analysis. Journal of the Iron and Steel Institute 176, January1954,2936. Aluminium expected Test portion optimum mass

33、 Volume of sulfuric acid(3.28) Volume of mercury, minimum Steel, etc. FeCr, Cr %(m/m) 0 to0.10 0.10 to 0.20 0.20 to 0.50 0.50 to 1.0 g 10 5 2 1 mL 160 100 65 50 mL 200 120 70 55 mL 120 60 25 12BS6200-3.1.1:1991 BSI 10-1999 3 NOTEDimension is in millimetres. Figure 1 Mercury cathode assemblyBS6200-3.

34、1.1:1991 4 BSI 10-1999 6.3.3 Mercury cathode electrolysis To the filtrate add50mL of sodium carbonate solution(3.24) slowly and with constant stirring to ensure complete solution of any precipitate formed. Cool, transfer to the electrolytic cell(4.3) containing an appropriate volume of clean mercury

35、 (see Table 1) and dilute to approximately400mL. Electrolyse at a current density of0.15A/cm 2 , maintaining the temperature below50 C. The speed of the electrolysis can be increased by using a higher current density provided that the water cooling is adequate to keep the cell temperature below50 C.

36、 Continue the electrolysis until the solution is freed from iron, nickel, chromium,etc. and then for a further15min. Free acid is liberated during electrolysis and this may be sufficient to retard electro-deposition when solutions contain test portions of large mass, particularly with ferro-chromium

37、 and chromium metal. After most of the iron, chromium,etc. has been deposited, for each1g of test portion add10mL of sodium carbonate solution(3.24) to increase the speed of the final stages of electrolysis. Make the addition of sodium carbonate slowly and with constant stirring to avoid the formati

38、on of a permanent precipitate. The colour of the electrolyte is usually a sufficient indication of the completeness of electrolysis, but if desired this can be verified by an external spot test for iron or chromium. Disconnect the current supply, transfer the electrolyte to a1L squat beaker, rinse t

39、he cell several times with sulfuric acid(3.29), and combine the rinsings with the main solution. Filter the solution through a small paper-pulp pad and wash with sulfuric acid(3.29). Transfer to a650mL conical beaker and adjust the volume to250mL to300mL by boiling or dilution. Cool. 6.3.4 Prelimina

40、ry separation of aluminium Add1mL of iron(III) chloride solution(3.14),3mL of bromine solution(3.7) and boil until the solution is freed from bromine. Add1g of ammonium chloride(3.4), adjust to approximately80 C and add ammonia solution(3.3) slowly from a burette until the solution is just alkaline

41、using methyl red indicator(3.16). Boil gently for2min to3min and allow to stand at approximately60 C until the precipitate coagulates. Filter through an open-texture ashless filter paper and wash thoroughly with hot water. NOTEWhatman No.40 or equivalent is suitable. Dissolve the precipitate from th

42、e paper into the original beaker with hot hydrochloric acid(3.11). Add5mL of sulfuric acid(3.27), a few drops of nitric acid(3.17), and evaporate to fuming. Cool, dilute with75mL of water, boil to dissolve salts and cool to10 C. 6.3.5 Removal of interfering elements with cupferron Add cupferron solu

43、tion(3.8) slowly, with stirring, until precipitation is complete, as indicated by the coagulation of the precipitate; further addition of cupferron will produce only a white transient precipitate of the free base. Add1mL of excess cupferron solution(3.8), stir in a little paper-pulp, filter through

44、a paper-pulp pad and collect the filtrate in a400mL beaker. Wash with cold cupferron-acid wash solution(3.9) and discard the precipitate. To the filtrate add20mL of nitric acid(3.17) and evaporate to fuming. If necessary make further additions of the nitric acid and repeat the fuming until organic m

45、atter is destroyed. Cool, add30mL of water and heat until salts are dissolved. Dilute to70mL, add5mL of tartaric acid solution(3.30) and neutralize with ammonia solution(3.3) using methyl red indicator(3.16). Add10mL of potassium cyanide solution(3.20), heat to60 C and add25mL of ammonium sulfide so

46、lution(3.5). Digest at60 C for10min and cool. Filter through a paper-pulp pad into a400mL beaker and wash with ammonium sulfide wash solution(3.6), ensuring that the final volume does not exceed200mL. 6.3.6 Separation of aluminium Heat to boiling and, from a burette, add dropwise8mL of quinolin-8-ol

47、 solution(3.23), stirring throughout the addition. This addition will precipitate up to10mg of aluminium, but when less than2mg of aluminium is present make the addition as slowly as possible. Digest at90 C for10min, filter through a paper-pulp pad and wash with hot water. Dissolve the precipitate f

48、rom the pad into a500mL stoppered flask with100mL of nearly boiling hydrochloric acid(3.11) and wash the pad several times with hot water. Dilute the solution to approximately200mL and cool.BS6200-3.1.1:1991 BSI 10-1999 5 6.3.7 Titration of quinolin-8-ol Add three drops of indigo carmine indicator(3

49、.13) and titrate with potassium bromate solution(3.18) until the blue tint of the indicator is discharged. Add three more drops of indicator(3.13), continue the titration until the solution assumes a clear yellow colour, then add a further2mL of potassium bromate solution(3.18). Stopper the flask, mix, and allow to stand for5min. Remove the stopper, add10mL of potassium iodide solution(3.22), mix, and titrate with sodium thiosulfate solution(3.25) until the brown iodine colour is almost discharged. Add5mL of starch indicator solution(3.2