《BS-3338-2-1961.pdf》由会员分享，可在线阅读，更多相关《BS-3338-2-1961.pdf（10页珍藏版）》请在三一文库上搜索。
1、BRITISH STANDARD BS 3338-2: 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 alloys Licensed Copy: sheffieldun sheffieldun, na, Wed Nov 29 07:54:29 GMT+00:00 2006, Uncontrolled Copy,
2、(c) BSI BS 3338-2:1961 This British Standard, having been approved by the Non-ferrous Metals Industry Standards Committee and endorsed by the Chairman of the Engineering Divisional Council, was published under the authority of the General Council on 23 February 1961 BSI 12-1999 The following BSI ref
3、erences relate to the work on this standard: Committee references NFE/27/, NFE/27/1 Draft for comment A(NFE) 9199 ISBN 0 580 03027 X Co-operating organizations The Non-ferrous Metals Industry Standards Committee, under whose supervision this British Standard was prepared, consists of representatives
4、 from the following Government departments and scientific and industrial organizations: Admiralty*Institution of Mining and Metallurgy Aluminium Development AssociationInstitution of Structural Engineers Aluminium Industry CouncilLead Development Association Association of Bronze and Brass FoundersL
5、ead Sheet and Pipe Manufacturers Association of Consulting Engineers Federation (Incorporated)Light Metal Founders Association British Bronze and Brass Ingot London Metal Exchange* Manufacturers AssociationMagnesium Industry Council British Electrical and Allied Manufacturers Ministry of Aviation* A
6、ssociation*National Brassfoundry Association British Non-ferrous Metals FederationNon-ferrous Metal Stockists British Non-ferrous Metals Research Post Office* Association*Royal Institute of British Architects Cable Makers Association*Society of British Aircraft Constructors Copper Development Associ
7、ationSociety of Motor Manufacturers and Crown Agents for Oversea Governments and Traders Ltd.* AdministrationsTin Research Institute* High Commission of IndiaWar Office* High Conductivity Copper AssociationZinc Development Association Institute of British FoundrymenIndividual manufacturers Institute
8、 of Metals Institution of Mechanical Engineers (Automobile Division) The Government departments and scientific 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 Britis
9、h Standard: British Railways, The British Transport Solder Makers Association CommissionTin Producers Association British Tin Box Manufacturers FederationTinplate Conference (1925) Electronic Engineering AssociationWhite Metal Bearing Manufacturers Gas CouncilIndividual manufacturers Institution of
10、Gas Engineers London Transport Executive, The British Transport Commission Amendments issued since publication Amd. No.Date of issueComments 7163June 1992Indicated by a sideline in the margin Licensed Copy: sheffieldun sheffieldun, na, Wed Nov 29 07:54:29 GMT+00:00 2006, Uncontrolled Copy, (c) BSI B
11、S 3338-2:1961 BSI 12-1999i Contents Page Co-operating organizationsInside front cover Forewordii Introduction1 Apparatus1 Solutions required1 Other reagents1 Sampling1 Procedure3 Calculation3 Figure 1 Arrangement for filtering off precipitate2 Licensed Copy: sheffieldun sheffieldun, na, Wed Nov 29 0
12、7:54:29 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 3338-2:1961 ii BSI 12-1999 Foreword This standard makes reference to the following British Standard: BS 410, 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 Britis
13、h Standard 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
14、 the standardization of methods for the sampling and analysis of non-ferrous metals. Other methods in the series are as follows: Part 1: Sampling of ingot tin; Part 3: Determination of antimony in ingot tin; Part 4: Determination of copper in ingot tin and tin-lead solders; Part 5: Determination of
15、lead in ingot tin and tin-antimony solders; Part 6: Determination of copper in high purity ingot tin; Part 7: Determination of silver in solders; Part 8: Determination of bismuth in ingot tin, tin-lead solders and white metal bearing alloys; Part 9: Determination of arsenic in ingot tin, tin-lead so
16、lders and white metal bearing alloys; Part 10: Determination of iron in ingot tin, tin-lead solders and white metal bearing alloys; Part 11: Determination of tin in solders; Part 12: Sampling of solders. The complete British Standard methods will be found suitable for the grades of metals covered by
17、 BS 3252, “Ingot tin”, BS 219, “Soft solders”, and BS 3332, “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
18、 ingots. For amounts of impurity 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 “refer
19、ee” 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 application. Compliance with a British Standard does not of itself confer immunity from legal obligation
20、s. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages 1 to 4, 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 in
21、side front cover. Licensed Copy: sheffieldun sheffieldun, na, Wed Nov 29 07:54:29 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 3338-2:1961 BSI 12-19991 Introduction a) Principle. The sample is dissolved in hydrochloric acid, interfering impurities are removed, by precipitation with metallic iron, a
22、nd filtered off. The tin is then reduced with aluminium and titrated with standard potassium iodate/iodide solution. b) Range. From 99.0 to 99.8 per cent tin. c) Reproducibility. 0.05 per cent. Apparatus a) 500 ml flat bottomed flasks fitted with rubber stoppers carrying carbon dioxide leads and “ed
23、uction bulb” spray traps (see Figure 1). b) 1 in Jena slit-sieve funnel or alternatively a small heat-resistant mercury filter, porosity 1, fitted 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 o
24、f hot plate, water trough with running cold water for cooling the flasks, and a carbon dioxide manifold with an Arnold bottle serving as a bubbling indicator and a glass tap for each flask. d) 10 ml burette, preferably graduated in 0.02 ml. e) Any volumetric glassware used shall be of Class A accura
25、cy as defined in the appropriate British Standards, or where no British Standard exists, as described in the National Physical Laboratory Publication “Volumetric Tests on Volumetric Glassware”. Solutions required All reagents shall be of the highest purity obtainable and distilled water shall be use
26、d throughout. Solutions shall be freshly prepared and, where necessary, filtered. Antimony chloride (0.1 per cent w/v). Dissolve 0.1 g metallic antimony in 100 ml of hydrochloric acid (sp. gr. 1.16 to 1.18) with the aid of bromine. Hydrochloric acid (sp. gr. 1.16 to 1.18). Test as follows: To 100 ml
27、 of hydrochloric acid (sp. gr. 1.16 to 1.18) add 100 ml of water in a 500 ml round bottomed flask, together with 2.5 g of aluminium strip, and dissolve under carbon dioxide. Boil for a few minutes and allow to cool under the same atmosphere. When cold, disconnect from the gas supply, add 3 g of pure
28、 potassium iodide (free from iodate) dissolved in a little previously boiled and cooled water and 5 ml of starch solution. Reconnect and allow to stand. No blue colour should appear within 15 minutes. Hydrochloric acid (50 per cent v/v). Dilute 500 ml of hydrochloric acid (sp. gr. 1.16 to 1.18) to 1
29、 litre. Hydrochloric acid (10 per cent v/v). Dilute 100 ml of hydrochloric acid (sp. gr. 1.16 to 1.18) to 1 litre. Potassium iodate/iodide (1 ml = 0.0030 g potassium iodate). Dissolve 3 g of potassium iodate (previously ground to pass 90 mesh1) weighed accurately to 0.0001 g (Note 1), 3 g of potassi
30、um iodide and 0.5 g of sodium hydrogen carbonate in previously boiled and cooled water and dilute to 1 litre in a graduated flask. Sodium chlorate (20 per cent w/v). Dissolve 200 g of sodium chlorate in water and dilute to 1 litre. Starch. Make a suspension of 0.5 g of starch in 10 ml of water. Add
31、to 90 ml of boiling water. Cool and dilute to 100 ml. Prepare freshly each day. Other reagents Aluminium strip. 99.5 per cent pure, 1/2 in (12.7 mm) 1/16 in (1.59 mm) cut into lengths weighing about 2.5 g just under 2 in (50.8 mm). Iron powder. A mixture of approximately equal parts by volume of pur
32、e iron powder reduced by hydrogen (“Ferrum reductum”) and electrolytic iron powder, Grade 200 mesh to dust. Pure tin foil. For use as standards. Sampling Recommended methods of obtaining a suitable sample for the analytical procedure given below are described in BS 3338-1 “Sampling of ingot tin”. 1)
33、 BS 410, “Test sieves”. Licensed Copy: sheffieldun sheffieldun, na, Wed Nov 29 07:54:29 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 3338-2:1961 2 BSI 12-1999 Figure 1 Arrangement for filtering off precipitate Licensed Copy: sheffieldun sheffieldun, na, Wed Nov 29 07:54:29 GMT+00:00 2006, Uncontrol
34、led Copy, (c) BSI BS 3338-2:1961 BSI 12-19993 Procedure Weigh accurately to 0.0001 g (Note 1) six portions (see table below for quantities) of potassium iodate (previously ground to pass 90 mesh) and transfer each to a small beaker. To each add 1 g of sodium hydrogen carbonate, and 50 ml of previous
35、ly boiled and cooled water, cover the beaker, warm gently to dissolve the iodate and allow to cool and reserve. Weigh accurately to 0.0001 g (Note 1) triplicate portions of 2.5 g of sample, and of pure tin, and transfer each to a 250 ml tall unspouted beaker. To each of the assay portions and standa
36、rds add 50 ml of hydrochloric acid (sp. gr. 1.16 to 1.18) and one drop of antimony chloride solution (0.1 per cent), cover the beaker, and heat to about 45 C on a warm plate. Maintain at this temperature until the tin has dissolved leaving only a small black residue of impurities (Note 2). Oxidize t
37、he warm solution with 4 ml (measured to within 0.1 ml) of sodium chlorate solution (20 per cent) added slowly, with swirling. Cool to about 30 C in a shallow water trough. At 5 minute intervals (Note 3) remove three beakers at a time from the trough, and add to each about 1 g ( 0.25 g) of the iron p
38、owder. Allow to stand for 5 minutes, then replace in the trough. During the 5 minutes standing period of the second and subsequent sets of three beakers filter the contents of the previous three beakers through an ceramic fibre pad on a slit sieve or fritted funnel into 500 ml flat bottomed flasks,
39、containing 180 ml of hydrochloric acid (50 per cent) and 0.25 g of the iron powder. Wash with warm (30 to 35 C) hydrochloric acid (10 per cent) and in each case combine the washings with the filtrate. The volume in each flask should be 300 to 350 ml. Add to each flask 5 g of aluminium strip, connect
40、 to a supply of carbon dioxide, warm if necessary (Note 4), until the aluminium is dissolving briskly, then immerse in the cooling trough. Adjust the flow of carbon dioxide to a steady rate of 1 to 2 bubbles a second through the Arnold bottle, and leave the flask in the trough until the aluminium is
41、 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 acid (10 per cent), replace the stopper, and heat the flask slowly to boiling on the hot plate, regulati
42、ng 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 indicated by the absence of small frothy bubbles) swirling the flask if necessary to collect any specks above
43、 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 flask from the cooling trough, turn off the carbon dioxide supply, wash and remove the stopper and ca
44、p 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, swirling gently. Add 1 to 2 ml of starch solution, and titrate with the potassium iodate/iodide solution
45、, using a 10 ml burette and swirling gently (Note 5) 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 potassium iodate Pure tin Refined tin, T1 Common tin, T3 g 1.493 1.490 1.478 where A = weight (g
46、) 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 to 1 g of potassium iodate. W1= weight (g) of tin standard. C = weight (g) of potassium iodate added to standard. D = weight (g) of potassiu
47、m iodate added in titration. Tin per cent AB+()F W - -100= W1 CD+ - - Licensed Copy: sheffieldun sheffieldun, na, Wed Nov 29 07:54:29 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 3338-2:1961 4 BSI 12-1999 NOTE 2Until judgement has been acquired by experience, a blank should be used consisting of a
48、beaker containing 50 ml 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 4
49、Initial warming 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. Licensed Copy: sheffieldun sheffieldun, na, Wed Nov 29 07:54:29 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 3338-2:1961 BSI 12-1999 British Standards The following are available on application: YEARBOOK Including subject index and nume