1、BRITISH STANDARD BS1728-6: 1955 Method for The determination of iron in aluminium and aluminium alloys (volumetric: titanous chloride method) BS1728-6:1955 This British Standard, having been approved by the Non-ferrous Metals Industry Standards Committee and endorsed by the Chairman oftheEngineering
2、 Divisional Council, was published undertheauthority of the GeneralCouncil on 28February1955 BSI 11-1999 The following BSI references relate to the work on this standard: Committee referenceNFE/-/3 Draft for commentCR5205 ISBN 0 580 01509 2 Co-operating organizations The Non-ferrous Metals Industry
3、Standards Committee, under whose supervision this British Standard was prepared, consists of representatives from the following Government departments, and scientific and industrial organizations: Admiralty High Conductivity Copper Association Aluminium Development Association Institute of British F
4、oundrymen Aluminium Industry Council Institute of Metals Association of Bronze and Brass Founders Institution of Mechanical Engineers Association of Consulting Engineers, (Automobile Division) Incorporated Institution of Mining and Metallurgy Association of Non-ferrous Metal Stockists Institution of
5、 Structural Engineers Brass and Copper Tube Association Lead Sheet and Pipe Manufacturers Brass Wire Association Federation British Bronze and Brass Ingot Manufacturers Light Metal Founders Association* Association London Metal Exchange British Electrical and Allied Manufacturers Manufactured Copper
6、 Association Association Ministry of Supply* British Non-ferrous Metals Research National Brassfoundry Association Association* Nickel Silver Association Cable Makers Association Royal Institute of British Architects Cold Rolled Brass and Copper Association Sheet Makers Conference Copper Development
7、 Association Society of British Aircraft Constructors Crown Agents for Oversea Governments and Tin Research Institute Administrations Zinc Development Association General Post Office Individual manufacturers* High Commission of India The Government department and scientific and industrial organizati
8、ons marked with an asterisk in the above list, together with the following, were directly represented on the sub-committee entrusted with the preparation of this British Standard: ALAR (Association of Light Alloy Refiners) Individual analysts Department of the Government Chemist Amendments issued si
9、nce publication Amd. No. Date CommentsBS1728-6:1955 BSI 11-1999 i Contents Page Co-operating organizations Inside front cover Foreword ii Introduction 1 Reagents required 1 Sampling 1 Procedure 1 Figure 1 Apparatus for storing titanous chloride solution under hydrogen 3BS1728-6:1955 ii BSI 11-1999 F
10、oreword This standard makes reference to the following British Standard: BS1499, Sampling non-ferrous metals. This method for the determination of iron is the sixth of a series of methods for the analysis of aluminium and aluminium alloys. The series will form a complete British Standard, each metho
11、d being published as a separate part. Other methods in this series are as follows: Part1: Copper; Part2: Magnesium; Part3: Zinc (mercuric potassium thiocyanate method); Part4: Zinc (polarographic method); Part5: Copper (absorptiometric method); Part7: Zinc (zinc oxide method). The preparation of thi
12、s series of methods has been authorized by the Non-ferrous Metals Industry Standards Committee as part of a general programme of the standardization of methods for the analysis of non-ferrous metals. The methods given have been found to give reliable and reproducible results and, while in some insta
13、nces the methods may appear to be lengthy, it should be realized that they are put forward as “referee” methods to be used in cases of dispute. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct appl
14、ication. 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 to3 and a back cover. This standard has been updated (see copyright date) and may have had amendm
15、ents incorporated. This will be indicated in the amendment table on the inside front cover.BS1728-6:1955 BSI 11-1999 1 Introduction a) Principle. The alloy is dissolved in mixed acids and fumed with sulphuric acid. The siliceous residue is filtered off and any traces of retained iron are recovered b
16、y subsequent treatment of the ignited residue. Copper is precipitated by hydrogen sulphide and the copper sulphide is filtered off. The hydrogen sulphide is removed from the filtrate by boiling and the iron is oxidized and then determined by titration with titanous chloride solution. b) Range. The m
17、ethod is suitable for iron contents between0.1 and5.0per cent. c) Reproducibility. Experiments have been carried out by a number of independent analysts using the method recommended in this standard. The degree of reproducibility that can be expected is shown by the following analysis of the results
18、 obtained. Reagents required All reagents shall be of recognized analytical quality and distilled water shall be used throughout. Nitric acid (sp. gr.1.42). Sulphuric acid (sp. gr.1.84). Hydrofluoric acid (40per cent). Sulphuric acid 50per cent v/v in water. Sulphuric acid wash solution (1per cent v
19、/v in water). Hydrogen sulphide wash solution (1per cent v/v sulphuric acid freshly saturated with hydrogen sulphide). Potassium bisulphate powdered. Potassium permanganate solution approx. N/10. Potassium permanganate solution approx. N/56. Potassium thiocyanate solution 10per cent aqueous solution
20、. Standard titanous chloride solution. 1mlN 0.0008g Fe (for0.13per cent Fe) (seeNote1). Standard iron solution. 1mlN 0.001g Fe (see Note2). Sampling Recommended methods of obtaining a suitable sample for the analytical procedure given below are described in BS1499, “Sampling non-ferrous metals”. Pro
21、cedure Adjust the weight of the sample as follows: Iron content percent Standard deviation 0.19 0.0040 0.561 0.0046 2.06 0.0201 5.00 0.0241 Acid mixture. Sulphuric acid (sp.gr.1.84) 170ml Hydrochloric acid (sp.gr.1.18) 300ml Nitric acid (sp. gr.1.42) 300ml Water 600ml Add the sulphuric acid cautious
22、ly to the water, cool and add the hydrochloric and nitric acids. Iron content per cent Weight of sample Amount of acid mixture g ml 3.05.0 0.5 35 2.03.0 1.0 35 0.5 2.0 2.0 70 0.250.5 3.0 105 0.10.25 5.0 175BS1728-6:1955 2 BSI 11-1999 Place the sample, after removal of any adventitious iron, e.g.by m
23、eans of a magnet in a500800ml conical beaker, cover with a watch-glass and gradually add the appropriate volume of acid mixture. Cool if necessary. When the reaction ceases, raise the watch-glass on a small glass hook placed on the rim of the beaker and evaporate to sulphuric acid fumes. Fume for fi
24、ve minutes, cool to room temperature, add cautiously100150ml of warm water and5ml of50per cent sulphuric acid and boil gently for20minutes to ensure complete solution of the salts. Wash down the watch-glass and the hook with hot water and filter through an ashless paper-pulp pad or a hardened12.5cm
25、filter paper (Whatman No.540 is suitable), containing some ashless paper pulp into a second500ml conical beaker. Wash out the beaker and then wash the paper six to eight times with hot sulphuric acid wash solution. Retain the filtrate. Ignite the siliceous precipitate at a moderate temperature (atle
26、ss than600 C if copper is being determined) until the carbon has completely disappeared and transfer the ash to a platinum crucible. After cooling, treat the residue with0.5ml of sulphuric acid (sp.gr.1.84),23ml of hydrofluoric acid and then with1ml of nitric acid (sp. gr.1.42) added cautiously, add
27、ing more hydrofluoric acid, if necessary. Evaporate and re-ignite and add a weighed amount(23g) of potassium bisulphate. Cover with a platinum lid and heat until the residue has been taken into solution. Cool and extract with warm1per cent sulphuric acid into a100ml beaker. Boil into solution and th
28、en wash into the retained filtrate. Adjust the volume to about300ml. Heat the combined filtrate to6070 C and pass a steady stream of hydrogen sulphide through the solution for20minutes. Add some ashless paper pulp and stand for a few minutes to allow the precipitate to coagulate. Filter on a15cm pap
29、er (Whatman No.40 is suitable) containing ashless paper pulp. Wash out the beaker and then wash the paper six to eight times with warm hydrogen sulphide wash solution. (The precipitate may be retained for copper determination.) Place any convenient form of anti-bumping device, e.g.a bumping rod, in
30、the filtrate and evaporate to half volume. Wash round the inside of the beaker, and cool. Oxidize the iron in the cold solution by dropwise addition of theN/10 potassium permanganate solution until the solution is just pink (alternatively, titration withN/56 potassium permanganate solution gives a r
31、ough check for iron content). At once add10ml of potassium thiocyanate solution and titrate with the standard titanous chloride solution to a colourless end-point or the absence of any red ferric thiocyanate colour (pale pink if cobalt is present, green if chromium or nickel is present). Shake the s
32、ample well during the titration and add the titrant dropwise when within one or two millilitres of the end-point. When coloured ions are present it is advisable to process an extra sample and “overshoot” the end-point to enable the correct colour change to be observed on the samples. Carry out a bla
33、nk determination following the same procedure and using the same amounts of all reagents. Standardization of the titanous chloride solution. By means of a pipette transfer duplicate20ml aliquots of standard iron solution to a500ml conical beaker, dilute to about100ml, add5ml of50per cent sulphuric a
34、cid, oxidize with potassium permanganate and titrate as in the method. NOTE 1Standard titanous chloride solution. Add about100ml of titanous chloride solution (150g/litre) to200ml of concentrated hydrochloric acid in a litre beaker. Heat to boiling and boil for two minutes. Cool rapidly by diluting
35、with cold distilled water. Pour into a5-litre aspirator already nearly filled with distilled water. Mix well and fill to the brim with water. Take out from the tap about400ml in a dry beaker to enable the solution to be well stirred by swirling. Return the solution in the beaker to the aspirator. Ta
36、ke out a further portion in the same manner and mix the main solution. Return the solution in the beaker to the aspirator, so that it is now well mixed and quite full. Place in position the rubber bung carrying the tube to the burette and the hydrogen inlet tube, thus displacing a quantity of the so
37、lution. Remove all air from the tubes and fill all spaces with gas from the generator. Maintain an atmosphere of gas over the solution during storage. (Figure 1 illustrates a suitable apparatus.) NOTE 2Standard iron solution. Dissolve a weight of iron of known purity, not less than99.6per cent, to g
38、ive1.000g iron in50ml of20per cent v/v sulphuric acid, together with small additions of N potassium permanganate solution. Cool and dilute to one litre. 1mlN 0.001g iron.BS1728-6:1955 BSI 11-1999 3 Figure 1 Apparatus for storing titanous chloride solution under hydrogenBS1728-6: 1955 BSI 389 Chiswic
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