1、BRITISH STANDARD BS3338-2: 1961 Incorporating Amendment No.1 Method for The determination of tin in ingot tin (Aluminium reduction method) Methods for the sampling and analysis of tin and tin alloysBS3338-2:1961 This BritishStandard, having been approved by the Non-ferrous Metals Industry Standards
2、Committee and endorsed by the Chairman oftheEngineering Divisional Council, was published under theauthority of the General Council on 23February1961 BSI 12-1999 The following BSI references relate to the work on this standard: Committee referencesNFE/27/, NFE/27/1 Draft for comment A(NFE)9199 ISBN
3、0 580 03027X Co-operating organizations The Non-ferrous Metals Industry Standards Committee, under whose supervision this BritishStandard was prepared, consists of representatives from the following Government departments and scientific and industrial organizations: Admiralty* Institution of Mining
4、and Metallurgy Aluminium Development Association Institution of Structural Engineers Aluminium Industry Council Lead Development Association Association of Bronze and Brass Founders Lead Sheet and Pipe Manufacturers Association of Consulting Engineers Federation (Incorporated) Light Metal Founders A
5、ssociation British Bronze and Brass Ingot London Metal Exchange* Manufacturers Association Magnesium Industry Council British Electrical and Allied Manufacturers Ministry of Aviation* Association* National Brassfoundry Association British Non-ferrous Metals Federation Non-ferrous Metal Stockists Bri
6、tish Non-ferrous Metals Research Post Office* Association* Royal Institute of British Architects Cable Makers Association* Society of British Aircraft Constructors Copper Development Association Society of Motor Manufacturers and Crown Agents for Oversea Governments and Traders Ltd.* Administrations
7、 Tin Research Institute* High Commission of India War Office* High Conductivity Copper Association Zinc Development Association Institute of British Foundrymen Individual manufacturers Institute of Metals Institution of Mechanical Engineers (Automobile Division) The Government departments and scient
8、ific and industrial organizations marked with an asterisk in the above list, together with the following, were directly represented on the committee entrusted with the preparation of this BritishStandard: British Railways, The British Transport Solder Makers Association Commission Tin Producers Asso
9、ciation British Tin Box Manufacturers Federation Tinplate Conference(1925) Electronic Engineering Association White Metal Bearing Manufacturers Gas Council Individual manufacturers Institution of Gas Engineers London Transport Executive, The British Transport Commission Amendments issued since publi
10、cation Amd. No. Date of issue Comments 7163 June1992 Indicated by a sideline in the marginBS3338-2:1961 BSI 12-1999 i Contents Page Co-operating organizations Inside front cover Foreword ii Introduction 1 Apparatus 1 Solutions required 1 Other reagents 1 Sampling 1 Procedure 3 Calculation 3 Figure 1
11、 Arrangement for filtering off precipitate 2BS3338-2:1961 ii BSI 12-1999 Foreword This standard makes reference to the following BritishStandard: BS410, Test sieves. This method for the determination of tin in ingot tin is the second of a series of methods which will form a complete BritishStandard
12、under the collective title “Methods for the sampling and analysis of tin and tin alloys”, each method being published as a separate part. The preparation of this series of methods has been authorized by the Non-ferrous Metals Industry Standards Committee as part of a general programme for the standa
13、rdization of methods for the sampling and analysis of non-ferrous metals. Other methods in the series are as follows: Part1: Sampling of ingot tin; Part3: Determination of antimony in ingot tin; Part4: Determination of copper in ingot tin and tin-lead solders; Part5: Determination of lead in ingot t
14、in and tin-antimony solders; Part6: Determination of copper in high purity ingot tin; Part7: Determination of silver in solders; Part8: Determination of bismuth in ingot tin, tin-lead solders and white metal bearing alloys; Part9: Determination of arsenic in ingot tin, tin-lead solders and white met
15、al bearing alloys; Part10: Determination of iron in ingot tin, tin-lead solders and white metal bearing alloys; Part11: Determination of tin in solders; Part12: Sampling of solders. The complete BritishStandard methods will be found suitable for the grades of metals covered by BS3252, “Ingot tin”, B
16、S219, “Soft solders”, and BS3332, “White metal bearing alloy ingots”. In the methods for determining impurities, sample weights and aliquots have been chosen to cover the range of impurity content usually found in commercial tin ingots, solders and white metal bearing alloy ingots. For amounts of im
17、purity outside this range, sample weights or aliquots should be adjusted accordingly. The methods have been found to give reliable and reproducible results, and, while in some instances they may appear to be lengthy, it should be realized that they are put forward as “referee” methods to be used in
18、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 application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This d
19、ocument comprises a front cover, an inside front cover, pagesi andii, pages1 to4, an inside back cover and a back cover. This 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.BS3338-2:1961
20、 BSI 12-1999 1 Introduction a) Principle. The sample is dissolved in hydrochloric acid, interfering impurities are removed, by precipitation with metallic iron, and filtered off. The tin is then reduced with aluminium and titrated with standard potassium iodate/iodide solution. b) Range. From99.0 to
21、99.8 per cent tin. c) Reproducibility. 0.05 per cent. Apparatus a) 500ml flat bottomed flasks fitted with rubber stoppers carrying carbon dioxide leads and “eduction bulb” spray traps (seeFigure 1). b) 1in Jena slit-sieve funnel or alternatively a small heat-resistant mercury filter, porosity1, fitt
22、ed into a rubber stopper carrying also a suction lead, the stopper being of the size required to fit the above flasks. c) A reduction apparatus consisting of hot plate, water trough with running cold water for cooling the flasks, and a carbon dioxide manifold with an Arnold bottle serving as a bubbl
23、ing indicator and a glass tap for each flask. d) 10ml burette, preferably graduated in0.02ml. e) Any volumetric glassware used shall be of Class A accuracy as defined in the appropriate BritishStandards, or where no BritishStandard exists, as described in the National Physical Laboratory Publication
24、 “Volumetric Tests on Volumetric Glassware”. Solutions required All reagents shall be of the highest purity obtainable and distilled water shall be used throughout. Solutions shall be freshly prepared and, where necessary, filtered. Antimony chloride (0.1 per cent w/v). Dissolve0.1g metallic antimon
25、y in100ml of hydrochloric acid (sp. gr.1.16 to1.18) with the aid of bromine. Hydrochloric acid (sp. gr.1.16 to1.18). Test as follows: To100ml of hydrochloric acid (sp. gr.1.16 to1.18) add100ml of water in a500ml round bottomed flask, together with2.5g of aluminium strip, and dissolve under carbon di
26、oxide. Boil for a few minutes and allow to cool under the same atmosphere. When cold, disconnect from the gas supply, add3g of pure potassium iodide (free from iodate) dissolved in a little previously boiled and cooled water and5ml of starch solution. Reconnect and allow to stand. No blue colour sho
27、uld appear within15minutes. Hydrochloric acid (50per cent v/v). Dilute500ml of hydrochloric acid (sp. gr.1.16 to1.18) to1litre. Hydrochloric acid (10per cent v/v). Dilute100ml of hydrochloric acid (sp. gr.1.16 to1.18) to1litre. Potassium iodate/iodide (1ml=0.0030g potassium iodate). Dissolve3g of po
28、tassium iodate (previously ground to pass90mesh 1) ) weighed accurately to0.0001g (Note1), 3g of potassium iodide and0.5g of sodium hydrogen carbonate in previously boiled and cooled water and dilute to1litre in a graduated flask. Sodium chlorate (20per cent w/v). Dissolve200g of sodium chlorate in
29、water and dilute to1 litre. Starch. Make a suspension of0.5g of starch in10ml of water. Add to90ml of boiling water. Cool and dilute to100ml. Prepare freshly each day. Other reagents Aluminium strip. 99.5per cent pure, 1 / 2in(12.7mm) 1 / 16in (1.59mm) cut into lengths weighing about2.5g just under2
30、 in (50.8mm). Iron powder. A mixture of approximately equal parts by volume of pure iron powder reduced by hydrogen (“Ferrum reductum”) and electrolytic iron powder, Grade200 mesh to dust. Pure tin foil. For use as standards. Sampling Recommended methods of obtaining a suitable sample for the analyt
31、ical procedure given below are described in BS3338-1 “Sampling of ingot tin”. 1) BS410, “Test sieves”.BS3338-2:1961 2 BSI 12-1999 Figure 1 Arrangement for filtering off precipitateBS3338-2:1961 BSI 12-1999 3 Procedure Weigh accurately to0.0001g (Note1) six portions (see table below for quantities) o
32、f potassium iodate (previously ground to pass90 mesh) and transfer each to a small beaker. To each add1g of sodium hydrogen carbonate, and50ml of previously boiled and cooled water, cover the beaker, warm gently to dissolve the iodate and allow to cool and reserve. Weigh accurately to0.0001g (Note1)
33、 triplicate portions of2.5g of sample, and of pure tin, and transfer each to a250ml tall unspouted beaker. To each of the assay portions and standards add50ml of hydrochloric acid (sp. gr.1.16 to1.18) and one drop of antimony chloride solution(0.1percent), cover the beaker, and heat to about45 C on
34、a warm plate. Maintain at this temperature until the tin has dissolved leaving only a small black residue of impurities (Note2). Oxidizethe warm solution with4ml (measured to within0.1ml) of sodium chlorate solution(20percent) added slowly, with swirling. Cool to about30 C in a shallow water trough.
35、 At5 minute intervals (Note3) remove three beakers at a time from the trough, and add to each about1g( 0.25g) of the iron powder. Allow to stand for5 minutes, then replace in the trough. During the5 minutes standing period of the second and subsequent sets of three beakers filter the contents of the
36、 previous three beakers through an ceramic fibre pad on a slit sieve or fritted funnel into500ml flat bottomed flasks, containing180ml of hydrochloric acid (50 per cent) and0.25g of the iron powder. Wash with warm(30 to35 C) hydrochloric acid(10 per cent) and in each case combine the washings with t
37、he filtrate. The volume in each flask should be300 to350ml. Add to each flask5g of aluminium strip, connect to a supply of carbon dioxide, warm if necessary (Note4), until the aluminium is dissolving briskly, then immerse in the cooling trough. Adjust the flow of carbon dioxide to a steady rate of1
38、to2 bubbles a second through the Arnold bottle, and leave the flask in the trough until the aluminium is almost dissolved, when any small residue should be dissolving quietly at the surface of the solution. Loosen the stopper, and rinse down the neck of the flask and the bung with warm hydrochloric
39、acid(10per cent), replace the stopper, and heat the flask slowly to boiling on the hot plate, regulating the rate so that most of the spongy mass of tin has re-dissolved quietly and steadily by the time the boiling point is reached. Continue to boil gently until all the tin has dissolved (as indicat
40、ed by the absence of small frothy bubbles) swirling the flask ifnecessary to collect any specks above the water line. Remove the flask from the hot plate, close the exit tube with a rubber cap, increase the pressure of carbon dioxide and immerse and cool the flask in the cooling trough. Remove each
41、flask from the cooling trough, turn off the carbon dioxide supply, wash and remove the stopper and cap the neck of the flask with palm of the hand while carrying to the burette, and add one of the previously prepared solutions, rinsing this into the flask with previously boiled and cooled water, swi
42、rling gently. Add1 to2ml of starch solution, and titrate with the potassium iodate/iodide solution, using a10ml burette and swirling gently (Note5) until the first faint tinge of blue persists. Calculation NOTE 1All the weighings in the series should be made in close succession. Material Weight of p
43、otassium iodate Pure tin Refined tin, T1 Common tin, T3 g 1.493 1.490 1.478 where A = weight (g) of potassium iodate added to sample. B = weight (g) of potassium iodate added in titration. W = weight (g) of sample taken. F = =weight (g) of tin equivalent to1g of potassium iodate. W 1 = weight (g) of
44、 tin standard. C = weight (g) of potassium iodate added to standard. D = weight (g) of potassium iodate added in titration. Tin per cent AB + ()F W -100 = W 1 CD + -BS3338-2:1961 4 BSI 12-1999 NOTE 2Until judgement has been acquired by experience, a blank should be used consisting of a beaker contai
45、ning50ml of water and a thermometer, on the hot plate. It is essential to avoid approaching boiling point, as this may cause oxidation and loss of stannic chloride. NOTE 3The iron precipitation of impurities should be timed by means of a clock to ensure uniformity of treatment. NOTE 4Initial warming
46、 will probably be necessary only with samples of common tin. NOTE 5Swirling is necessary to avoid undue loss of the carbon dioxide blanket in the flask and to prevent absorption of oxygen from the air. Brisk turbulent agitation should be avoided.BS3338-2:1961 BSI 12-1999 BritishStandards The followi
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