1、BRITISH STANDARD BS3907-9: 1969 Method for The determination of zinc in magnesium alloys (Ion-exchange Volumetric EDTA method) Methods for the analysis of magnesium and magnesium alloysBS3907-9:1969 This BritishStandard, having been approved by the Non-ferrous Metals Industry Standards Committee, wa
2、s published under the authority ofthe Executive Board on 18March1969 BSI12-1999 The following BSI references relate to the work on this standard: Committee references NFE/23 andNFE/23/4 Draft for comment67/32423 ISBN 0 580 04389 4 Co-operating organizations The Non-ferrous Metals Industry Standards
3、Committee, under whose supervision this BritishStandard was prepared, consists of representatives from the following Government departments and scientific and industrial organizations: The Government department and scientific and industrial organizations marked with an asterisk in the above list, to
4、gether with the following, were directly represented on the committee entrusted with the preparation of this BritishStandard: Aluminium Federation Institution of Mining and Metallurgy Association of Bronze and Brass Founders Institution of Production Engineers Association of Consulting Engineers Ins
5、titution of Structural Engineers Board of Trade Lead Development Association British Bronze and Brass Ingot Light Metal Founders Association Manufacturers Association London Metal Exchange British Electrical and Allied Manufacturers Magnesium Industry Council* Association Ministry of Defence, Army D
6、epartment* British Lead Manufacturers Association Ministry of Defence, Navy Department British Non-ferrous Metals Federation National Brassfoundry Association British Non-Ferrous Metals Federation Non-ferrous Metal Stockists* High Conductivity Copper Group Post Office British Non-ferrous Metals Rese
7、arch Royal Institute of British Architects Association* Society of British Aerospace Companies Ltd. Copper Development Association Society of Motor Manufacturers and Crown Agents for Oversea Governments Traders Ltd.* and Administrations Tin Research Institute Electric Cable Makers Confederation Zinc
8、 Development Association Institute of British Foundrymen Individual manufacturer Institute of Metals Institution of Mechanical Engineers (Automobile Division) Institute of Sheet Metal Engineering Individual analysts Ministry of Technology Ministry of Technology Laboratory of the Government Chemist A
9、mendments issued since publication Amd. No. Date CommentsBS3907-9:1969 BSI 12-1999 i Contents Page Co-operating organizations Inside front cover Foreword ii 1 Introduction 1 2 Apparatus 1 3 Solutions required 1 4 Sampling 1 5 Procedure 1 6 Standardization 2 7 Calculation 2 8 Notes 2BS3907-9:1969 ii
10、BSI 12-1999 Foreword This standard makes reference to the following BritishStandards: BS1499, Sampling non-ferrous metals. BS3978, Water for laboratory use. This method for the determination of zinc in magnesium alloys is the ninth of a series which will form a complete BritishStandard under the col
11、lective title “Methods for the analysis of magnesium and magnesium alloys” each being published as a separate part. Other methods in the series are as follows: Part1: Aluminium (gravimetric method); Part2: Iron (photometric1.10 phenanthroline method); Part3: Copper (photometric method); Part4: Manga
12、nese (photometricperiodate method); Part5: Manganese (photometricperiodate method) (low contents); Part6: Zirconium (photometric method); Part7: Nickel (photometric method); Part8: Total rare earths (gravimetric method) 1) ; Part10: Manganese in magnesium alloys containing zirconium, rare earths, th
13、orium and/or silver (photometric method); Part11: Silicon (photometric method) 1) . 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 standardization of methods for the sampling and analysis of
14、non-ferrous metals. 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 appreciated that they are primarily intended as “referee” methods to be used in cases of dispute. This method is substantially the same a
15、s the corresponding method approved by ISO/TC79 which will be published as ISOR . . . . 1) . 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 no
16、t of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pagesi andii, pages1 and 2 and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the
17、amendment table on the inside front cover. 1) In course of preparation.BS3907-9:1969 BSI 12-1999 1 1 Introduction 1.1 Principle. The sample is dissolved in hydrochloric acid and zinc is separated from other elements by absorption on to an anion exchange resin from a2N hydrochloric acid solution. Zin
18、c is removed from the resin with N/200 hydrochloric acid and determined volumetrically with EDTA. 1.2 Range. The method is recommended for zinc contents between0.10% and8.0%. 1.3 Reproducibility. Experiments have been carried out independently by a number of analysts using this method. The degree of
19、 reproducibility that can be expected is shown by the following analysis of the results obtained: 1.4 Application. This method is not suitable for magnesium alloys containing cadmium. 2 Apparatus 2.1 Class A volumetric glassware complying with the appropriate BritishStandards shall be used throughou
20、t. 2.2 Anion exchange column. Glass column20mm diameter and about400mm long, fitted with a tap and filled with resin 2)to a bed depth of150mm. First remove any fine particles present in the anion resin by successive washings with hydrochloric acid (N/200). Decant until a clear solution is obtained,
21、then allow the resin to stand for several hours (preferably overnight) in hydrochloric acid (N/200). Place a little glass wool at the bottom of the column above the tap as a support for the resin. Transfer the suspension of resin to the column to a depth of150mm, taking care to avoid the formation o
22、f air bubbles and channels. Wash the column with100ml of hydrochloric acid (N/200) at a rate of5ml to7mlperminute. Condition the exchange column by introducing, at the same rate,200ml of hydrochloric acid(2N) to which0.5ml of nitric acid (sp.gr.1.42) has been added. While the column is being prepare
23、d and during the analysis, the resin should always be covered by the liquid. 3 Solutions required All reagents shall be of the highest purity obtainable and either distilled or demineralized water complying with BS3978 3)shall be used throughout. Solutions shall be freshly prepared and where necessa
24、ry filtered. Standard zinc (1mlN 2mg of zinc). Dissolve2g of high-purity zinc in25ml of hydrochloric acid (sp.gr.1.161.18) diluted with75ml of water, transfer to a1litre volumetric flask, dilute to the mark and mix. EDTA (M/50). Dissolve7.5g of the disodium salt of diaminoethane tetra-acetic acid, (
25、EDTA), in water, transfer to a1litre volumetric flask, dilute to the mark and mix. Acetic acid (6%v/v). Dilute60ml of glacial acetic acid to1litre and mix. Ammonium acetate (50%w/v). Dissolve500g of ammonium acetate in water, dilute to1litre and mix. Dithizone (0.025%w/v). Dissolve0.025g of dithizon
26、e in ethanol and dilute to100ml with ethanol. 4 Sampling Recommended methods of obtaining a suitable sample for the analytical procedure given below and described in BS1499, “Sampling non-ferrous metals”. 5 Procedure 5.1 Weigh4 0.001g of sample and transfer to a400ml beaker. Add about50ml of water,
27、then gradually add30ml of hydrochloric acid (sp.gr.1.161.18). 5.2 Carry out simultaneously a blank determination following the same procedure and using the same amount of reagents as with the sample. Zinc content Standard deviation % 0.6 5.2 0.005 0.05 2) A resin with23% cross-linking, e.g.Permutit
28、Deacidite FF, (SRA62)52+100 mesh, or equivalent is suitable. 3) BS3978, “Water for laboratory use”. Hydrochloric acid (2N) Dilute170ml of hydrochloric acid (sp.gr.1.161.18) to1litre and mix. (N) Dilute85ml of hydrochloric acid (sp.gr.1.161.18) to1litre and mix. (N/200) Dilute5ml of hydrochloric acid
29、 (N) to1litre and mix.BS3907-9:1969 2 BSI 12-1999 5.3 When the reaction appears to be complete, add two drops of hydrogen peroxide(100vol) and heat gently to boiling. Continue boiling gently until all the hydrogen peroxide has decomposed then cool. 5.3.1 For zinc contents of1% or less. Use the whole
30、 of this solution. 5.3.2 For zinc contents greater than1%. Transfer the solution to a(50ml volumetric flask, dilute to the mark and mix, then take an aliquot of this solution as indicated in the table below: and transfer to a250ml beaker. 5.4 Place the beaker on a boiling water bath and evaporate ju
31、st to crystallization Allow to cool; take up with a100ml of hydrochloric acid(2N) and0.5ml of nitric acid (sp.gr.1.42) and heat to facilitate solution. 5.5 If the solution contains insoluble zirconium, or if during the evaporation silica has been precipitated, filter the solution through a fine filt
32、er and wash throughly with small quantities of warm hydrochloric acid solution(2N). 5.6 Cool, then pass the solution through the exchange column at a rate of5ml to7mlperminute. Wash the beaker and the exchange column with four successive25ml portions of hydrochloric acid(2N) followed by200ml of hydr
33、ochloric acid (N) at the rate of5ml to7mlperminute. Discard the effluent. 5.7 Elute the zinc retained on the resin by passing250ml of hydrochloric acid(N/200) through the exchange column at the same rate. 5.8 Collect the eluate in a500ml conical flask. Evaporate to70100ml and cool. Add ammonia solut
34、ion (sp.gr.0.91) dropwise until the solution is neutral to litmus. 5.9 Add20ml of acetic acid(6%) and10ml of ammonium acetate solution50% (Note8.1) then add50ml of acetone and2ml of dithizone indicator solution(0.025%). 5.10 Titrate with EDTA solution (M/50) until the colour of the indicator changes
35、 from red to orange yellow. 6 Standardization 6.1 EDTA (M/50). Transfer25ml of standard zinc solution(1mlN 2mg of zinc) to a conical flask and dilute to about100ml. Add ammonia solution (sp.gr.0.91) dropwise until the solution is neutral to litmus. 6.2 Continue from5.9 of the procedure. 7 Calculatio
36、n 1ml of EDTA solution (M/50)N 1.3076mg of zinc. 8 Notes Check the pH and if necessary adjust to between5 and5.5 with acetic acid or ammonia solution added dropwise. Zinc content Aliquot to be taken Corresponding sample weight % 1 to3 3 to6 6 to8 ml 100 50 25 g 1.6 0.8 0.4 where A = volume(ml) of ED
37、TA solution (M/50) used corrected for blank, B = volume(ml) of EDTA solution (M/50) used for standardization corrected for blank, R = ratio of volume of main solution to volume of aliquot taken, W = weight(g) of sample taken. zinc per cent A 5 R WB - =blankBS3907-9: 1969 BSI 389 Chiswick High Road L
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