1、BRITISH STANDARD BS3907-8: 1970 Method for The determination of total rare earths in magnesium alloys (Gravimetric method) Methods for the analysis of magnesium and magnesium alloysBS3907-8:1970 This BritishStandard, having been approved by the Non-ferrous Metals IndustryStandards Committee,was publ
2、ished underthe authority ofthe Executive Board on 30October1970 BSI12-1999 The following BSI references relate to the work on this standard: Committee references NFE/23 andNFE/23/4 Draft for comment69/22088 ISBN 0 580 06174 4 Co-operating organizations The Non-ferrous Metals Industry Standards Commi
3、ttee, under whose supervision this BritishStandard was prepared, consists of representatives from the following Government departments and scientific and industrial organizations: Aluminium Federation Institution of Mining and Metallurgy Association of Bronze and Brass Founders Institution of Produc
4、tion Engineers Association of Consulting Engineers Institution of Structural Engineers Board of Trade Lead Development Association British Bronze and Brass Ingot Manufacturers Light Metal Founders Association Association London Metal Exchange British Lead Manufacturers Association Magnesium Industry
5、 Council* British Non-ferrous Metals Federation Ministry of Defence (Army)* British Non-ferrous Metals FederationsHigh Ministry of Defence (Navy) Conductivity Copper Group National Brassfoundry Association British Non-ferrous Metals Research Non-ferrous Metal Stockists* Association* Post Office Copp
6、er Development Association Royal Institute of British Architects Crown Agents for Oversea Governments and Society of Motor Manufacturers and Traders Administrations Ltd.* Electric Cable Makers Confederation Tin Research Institute Institute of British Foundrymen Zinc Development Association Institute
7、 of Metals Individual manufacturers Institution of Mechanical Engineers (Automobile Division) The Government department 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 pr
8、eparation of this BritishStandard: Institute of Sheet Metal Engineering Individual analysts Ministry of Technology Ministry of TechnologyLaboratory of the Government Chemist Amendments issued since publication Amd. No. Date CommentsBS3907-8:1970 BSI 12-1999 i Contents Page Co-operating organizations
9、 Inside front cover Foreword ii 1 Introduction 1 2 Apparatus 1 3 Solutions required 1 4 Sampling 1 5 Procedure 1 6 Calculation 2BS3907-8:1970 ii BSI 12-1999 Foreword This standard makes reference to the following BritishStandards: BS1499, Sampling non-ferrous metals. BS3978, Water for laboratory use
10、. This method for the gravimetric determination of total rare earths in magnesium alloys is the eighth of a series which will form a complete BritishStandard under the collective title “Methods for the analysis of magnesium and magnesium alloys” each being published as a separate part. Other methods
11、 in the series are as follows: Part 1: Aluminium (gravimetric method); Part 2: Iron (photometric 1:10 phenanthroline method); Part 3: Copper (photometric method); Part 4: Manganese (photometric periodate method); Part 5: Manganese (photometric periodate method) (low contents); Part 6: Zirconium (pho
12、tometric method); Part 7: Nickel (photometric method); Part 9: Zinc (ion-exchange-volumetric EDTA method); Part 10: Manganese in magnesium alloys containing zirconium, rare earths, thorium and/or silver (photometric method); Part 11: Silicon (photometric method); Part 12: Aluminium (photometric meth
13、od) 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 non-ferrous metals. The methods have been found to give reliable and reprod
14、ucible 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 as the corresponding method approved by ISO/TC79, which will be published as
15、 ISO/R. 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 not of itself confer immunity from legal obligations. Summary of pages This document
16、 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 amendment table on the inside front cover. 1) In course of preparation.BS3907-8:19
17、70 BSI 12-1999 1 1 Introduction 1.1 Principle. The sample is dissolved in hydrochloric acid. Zirconium is precipitated with ammonia and filtered off. Rare earths are separated from the filtrate in the form of sebacate. The precipitate is redissolved and the rare earths are precipitated as oxalates,
18、ignited and weighed as rare earths oxides. 1.2 Range. The method is suitable for rare earth contents between0.2 and10%. 1.3 Reproducibility. Experiments have been carried out independently by a number of analysts using this method. The degree of reproducibility that can be expected is shown by the f
19、ollowing analysis of the results obtained. 1.4 Application. The method is not applicable to alloys containing thorium as this element precipitates with the rare earths. 2 Apparatus Class A volumetric glassware complying with the appropriate BritishStandards shall be used throughout. 3 Solutions requ
20、ired All reagents shall be of the highest purity obtainable and either distilled or demineralized water complying with BS3978 2)shall be used throughout. Solutions shall be freshly prepared and where necessary filtered. Ammonia (50%v/v): Dilute50ml of ammonia solution (sp.gr.0.91) to100ml and mix. A
21、mmonia (25%v/v): Dilute25ml of ammonia solution (sp.gr.0.91) to100ml and mix. Ammonia (2%v/v): Dilute2ml of ammonia solution (sp.gr.0.91) to100ml and mix. Nitric acid-hydrogen peroxide: Dilute30ml of hydrogen peroxide (100vol.) with150ml of water and add30ml of nitric acid (sp.gr.1.42). Oxalic acid
22、(saturated): Dissolve150g of oxalic acid in1litre of hot water, allow to cool, and filter. Oxalic acid wash solution: Dilute70ml of oxalic acid solution (saturated) to500ml and mix. Sebacic acid (5%w/v): Dissolve50g of sebacic acid HOOC (CH 2 ) 8 COOH in400ml of ammonia solution (sp.gr.0.91) and300m
23、l of water. Filter, dilute to one litre and mix. Sodium hydroxide (0.5%w/v): Dissolve5g of sodium hydroxide in water, dilute to one litre and mix. Bromophenol blue (0.4%w/v): Transfer0.4g of bromophenol blue to a mortar, add8.25ml of sodium hydroxide solution (0.5%) and crush to complete dissolution
24、. Transfer to a100ml volumetric flask, dilute to the mark and mix. 4 Sampling Recommended methods of obtaining a suitable sample for the analytical procedure given below are described in BS1499, “Sampling non-ferrous metals”. 5 Procedure 5.1 Adjust the weight of sample and quantity of hydrochloric a
25、cid to be used as follows: 5.2 Transfer the appropriate weight of sample to a600ml beaker. Add the appropriate volume of water, cover the beaker with a watchglass, then carefully add in small portions the appropriate volume of hydrochloric acid (sp.gr.1.161.18). When the vigorous reaction subsides,
26、boil the solution for a few minutes and filter through a medium texture filter paper containing a little paper pulp, collecting the filtrate in a second600ml beaker. Thoroughly wash the original beaker and filter with hot water and add the washings to the filtrate. Adjust the volume to about100ml an
27、d cool. Discard the residue. 5.3 Add three drops of bromophenol blue indicator(0.4%) to the solution and neutralize first with ammonia solution (50%) then with ammonia solution (25%) until the colour of the indicator changes to purple. Heat to boiling, remove the beaker and allow to stand for5minute
28、s, stirring frequently. 5.4 Filter through a medium textured filter paper and thoroughly wash the paper and precipitate with boiling water. Adjust the volume to250ml (filtrateA). Rare earth content Standard deviation % 1.03 1.52 2.65 0.011 0.014 0.018 2) BS3978, “Water for laboratory use”. Rare eart
29、h content Weight of sample Hydrochloric acid (sp.gr.1.161.18) Water % 0.22 25 510 g 5 0.001 2 0.001 1 0.001 ml 50 20 10 ml 100 40 20BS3907-8:1970 2 BSI 12-1999 5.5 Dissolve the precipitate on the filter with10ml of boiling nitric acidhydrogen peroxide added in small portions, washing with boiling wa
30、ter after each addition. Finally complete the washing of the filter with hot water (5or6washings) and adjust the volume to about25ml (filtrateB). 5.6 Add10g of ammonium chloride to filtrate A (see5.4) and adjust the pH of the solution to between8.5 and9.5 by adding ammonia solution(50%). Heat on a h
31、ot plate just to boiling, remove the beaker and while stirring, add20ml of sebacic acid solution (5%). Allow to stand for15minutes, stirring from time to time. 5.7 Filter through a medium textured filter paper and thoroughly wash with ammonia solution (2%). Place the filter and the precipitate in a
32、porcelain crucible (previously ignited at950 C, cooled in a desiccator and weighed) and heat in an electric oven at800 C for approximately30minutes. Remove the crucible and allow to cool. 5.8 Transfer the contents of the crucible to the beaker containing filtrateB (see5.5), heat and then add2 or3 dr
33、ops of hydrogen peroxide (100vol.) to complete the dissolution of rare earth oxides. 5.9 Remove the beaker from the source of heat, wash the walls and dilute to approximately125ml. Add slowly while stirring25ml of oxalic acid solution (saturated). Place the beaker on a boiling water bath for30minute
34、s, then allow to stand for12hours (overnight) at room temperature. 5.10 Filter the precipitate through a close textured filter paper and thoroughly wash with oxalic acid wash solution. Transfer the filter and the precipitate to the porcelain crucible already used (see5.7), gently heat the filter at
35、about500 C until combustion of the filter is complete, then ignite to constant weight at950 C. 6 Calculation Rare earth metals %= where A =weight (g) of precipitate (“rare earth oxides”) W =weight (g) of sample taken f =factor a . a In a mixture of rare earth oxides ignited at950 C cerium is present
36、 as CeO 2 , lanthanum as La 2 O 3 , neodymium as Nd 2 O 3 , and praeseodymium as Pr 6 O 11 . The value f depends upon the relative proportions of each rare earth element present. Normally the factor f =0.832 is used for mixtures of rare earth elements in the ratio Ce50%, La25%, Nd14% andPr6%. Where
37、the major constituent of the rare earths is neodymium the factor0.857 should be used. Af 100 W -blankBS3907-8: 1970 BSI 389 Chiswick High Road London W4 4AL BSIBritishStandardsInstitution BSI is the independent national body responsible for preparing BritishStandards. It presents the UK view on stan
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