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1、BRITISH STANDARD BS 1728-22: 1972 Method for The determination of magnesium in aluminium and aluminium alloys (volumetric CDTA method) Licensed Copy: sheffieldun sheffieldun, na, Fri Nov 24 08:09:28 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 1728-22:1972 This British Standard, having been approve
2、d by the Non-ferrous Metals Industry Standards Committee, was published under the authority of the Executive Board on 14 September 1972 BSI 11-1999 The following BSI references relate to the work on this standard: Committee reference NFE/-/3 Draft for comment 71/40285 ISBN 0 580 07257 6 Co-operating
3、 organizations The Non-ferrous Metals Industry Standards Committee, under whose supervision this British Standard was prepared, consists of representatives from the following Government departments and scientific and industrial organizations: Aluminium Federation* Association of Bronze and Brass Fou
4、nders British Bronze and Brass Ingot Manufacturers Association British Electrical and Allied Manufacturers Association British Lead Manufacturers Association British Non-ferrous Metals Federation British Non-ferrous Metals Federation High Conductivity Copper Group British Non-ferrous Metals Research
5、 Association* Copper Development Association Department of Trade and Industry (Marine Division) Electric Cable Makers Confederation Institute of British Foundrymen Institute of Metals Institution of Mechanical Engineers (Automobile Division) Institution of Mining and Metallurgy Institution of Produc
6、tion Engineers Institution of Structural Engineers Lead Development Association Light Metal Founders Association* London Metal Exchange Magnesium Industry Council Ministry of Defence, Army Department* Ministry of Defence, Navy Department National Brassfoundry Association Non-ferrous Metal Stockists
7、Post Office Royal Institute of British Architects Society of Motor Manufacturers and Traders Ltd. Tin Research Institute Zinc Development Association Individual manufacturer The Government department and scientific and industrial organizations marked with an asterisk in the above list, together with
8、 the following, were directly represented on the sub-committee entrusted with the preparation of this British Standard: Association of Light Alloy Refiners and Smelters Ltd. Department of Trade and Industry Laboratory of the Government Chemist Individual analysts Amendments issued since publication
9、Amd. No.DateComments Licensed Copy: sheffieldun sheffieldun, na, Fri Nov 24 08:09:28 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 1728-22:1972 BSI 11-1999i Contents Page Co-operating organizationsInside front cover Forewordii 1Introduction1 2Apparatus1 3Solutions required1 4Sampling2 5Procedure2 6S
10、tandardization3 7Calculation4 8Notes4 Licensed Copy: sheffieldun sheffieldun, na, Fri Nov 24 08:09:28 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 1728-22:1972 ii BSI 11-1999 Foreword This standard makes reference to the following British Standards: BS 1499, Sampling non-ferrous metals. BS 3978, Wa
11、ter for laboratory use. This method for the determination of magnesium is the twenty-second of a series which will form a complete British Standard under the collective title “Methods for the analysis of aluminium and aluminium alloys”, each being published as a separate part. Other methods in the s
12、eries are as follows: Part 1: Copper; Part 2: Magnesium; Part 3: Zinc (mercuric potassium thiocyanate method); Part 5: Copper (absorptiometric method); Part 6: Iron (volumetric: titanous chloride method); Part 8: Iron (absorptiometric 1 : 10-phenanthroline method); Part 9: Manganese (volumetric:arse
13、nite/nitrite method); Part 10: Manganese (absorptiometric method); Part 11: Silicon (perchloric acid method); Part 12: Silicon (absorptiometric molybdenum blue method); Part 13: Titanium (absorptiometric chromotropic acid method); Part 14: Nickel (gravimetric method); Part 15: Nickel (photometric me
14、thod); Part 16: Chromium (photometric method); Part 17: Chromium (volumetric method); Part 18: Zinc (ion-exchange volumetric EDTA or polarographic method); Part 19: Magnesium (atomic absorption method); Part 20: Lead (atomic absorption method); Part 21: Zinc (atomic absorption method)1). The prepara
15、tion 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 reproducible results and,
16、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/TC 79 which will be published as International Stand
17、ard (ISO)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 Thi
18、s 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 inside front cover. 1) In
19、 course of preparation. Licensed Copy: sheffieldun sheffieldun, na, Fri Nov 24 08:09:28 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 1728-22:1972 BSI 11-19991 1 Introduction 1.1 Principle. The sample is dissolved in hydrochloric acid and the magnesium is co-precipitated with added iron from sodium
20、hydroxide solution. The precipitate is dissolved in hydrochloric acid, and residual iron, manganese, aluminium and titanium are precipitated with zinc oxide and potassium permanganate. The magnesium is titrated with CDTA in the presence of masking agents. 1.2 Range. The method is recommended for mag
21、nesium contents between 0.10 and 5 %. 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 following analysis of the results obtained. 2 Apparatus 2.1 Class A volumetric glas
22、sware complying with the appropriate British Standards shall be used throughout. 2.2 pH meter 3 Solutions required All reagents shall be of the highest purity obtainable2) and distilled or demineralized water complying with BS 39783) shall be used throughout. Standard magnesium (1 ml N 1 mg of magne
23、sium). Dissolve 1.0 g of high purity magnesium in 30 ml of hydrochloric acid (50 %). Transfer to a 1 litre volumetric flask, dilute to the mark and mix. Standard magnesium (1 ml N 0.2 mg of magnesium). Transfer 100 ml of standard magnesium solution (1 ml N 1 mg of magnesium) to a 500 ml volumetric f
24、lask, dilute to the mark and mix. CDTA (0.0 4M). Dissolve 15 g of CDTA (cyclohexanediamine-tetra-acetic acid) (HOOC.CH2)2N-CH(CH2)4CH-N(CH2COOH)2.H2O in about 500 ml of water containing 10 ml of sodium hydroxide solution (20 %) and mix. Then add sodium hydroxide solution (20 %) slowly with stirring
25、until the solid suspension dissolves. Dilute to about 800 ml and filter through a close textured filter paper into a 1 litre volumetric flask. Wash the filter with water and collect the washings in the volumetric flask. Dilute to the mark and mix. CDTA (0.01M). Transfer 250 ml of CDTA solution (0.04
26、M) to a 1 litre volumetric flask. Dilute to the mark and mix. Ammonia (50 % v/v). Dilute 500 ml of ammonia solution (sp. gr. 0.880.91) to 1 litre and mix. Ammonia (10 % v/v). Dilute 100 ml of ammonia solution (sp. gr. 0.880.91) to 1 litre and mix. Bromine water (saturated). To 100 ml of water add 5
27、ml of bromine, shake and allow to stand until saturated. EGTA (2 % w/v). Dissolve 2.0 g of EGTA ethylene glycol-bis (3-aminoethyl ether) tetra-acetic acid: (HOOC.CH2)2.NCH2CH2OCH2CH2OCH2CH2N(CH2COOH)2 in 25 ml of sodium hydroxide solution (2 %) and dilute to 100 ml. Ferric chloride (0.5 % w/v). Diss
28、olve 0.5 g of ferric chloride (FeCl3. 6H2O) in 10 ml of hydrochloric acid (20 %). Dilute to 100 ml and mix. Hydrochloric acid (50 % v/v). Dilute 500 ml of hydrochloric acid (sp. gr. 1.161.18) to 1 litre and mix. Hydrochloric acid (20 % v/v). Dilute 200 ml of hydrochloric acid (sp. gr. 1.161.18) to 1
29、 litre and mix. Hydrochloric acid (2.5 % v/v). Dilute 25 ml of hydrochloric acid (sp. gr. 1.161.18) to 1 litre and mix. Magnesium contentStandard deviation % 0.20.7 1.0 4.2 0.0060 0.018 0.033 2) For certain reagents an extra high quality is now available but this special grade of material is not req
30、uired unless specifically stated. 3) BS 3978 “Water for laboratory use”. Licensed Copy: sheffieldun sheffieldun, na, Fri Nov 24 08:09:28 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 1728-22:1972 2 BSI 11-1999 Hydroxylammonium chloride (2 % w/v). Dissolve 2.0 g of hydroxylammonium chloride in water.
31、 Dilute to 100 ml and mix. Industrial methylated spirit4)(25 % v/v). Dilute 25 ml of industrial methylated spirit to 100 ml and mix. Nitric acid (40 % v/v). Dilute 400 ml of nitric acid (sp. gr. 1.42) to 1 litre and mix. Potassium cyanide (25 % w/v). Dissolve 25 g of potassium cyanide in water. Dilu
32、te to 100 ml and mix. This solution should be freshly prepared. Potassium permanganate (1 % w/v). Dissolve 1 g of potassium permanganate in water. Dilute to 100 ml and mix. Sodium hydroxide (20 % w/v). Dissolve 200 g of sodium hydroxide in water. Dilute to 1 litre and mix. This solution should be pr
33、epared in a plastics beaker (water-cooled if necessary) and stored in a plastics bottle. Sodium hydroxide (2 % w/v). Dissolve 20 g of sodium hydroxide in water. Dilute to 1 litre and mix. Sulphuric acid (25 % v/v). To 400 ml of water add cautiously 250 ml of sulphuric acid (sp. gr. 1.8.4). Mix, cool
34、, dilute to 1 litre and mix. Indicator. Mix 0.1 g of methyl thymol blue (sodium salt of 3,3bis (NN-dicarboxy-methyl)-aminomethyl-thymol-sulphonphthalein) with 10 g of sodium chloride until homogeneous. 4 Sampling Recommended methods of obtaining a suitable sample for the analytical procedure given b
35、elow are described in BS 1499, “Sampling non-ferrous metals”. 5 Procedure 5.1 Weigh 2 0.001 g of sample and transfer to a 400 ml beaker. Add 50 ml of water. Then add gradually 50 ml of hydrochloric acid (50 %). 5.2 Carry out simultaneously a blank determination following the same procedure and using
36、 the same amounts of reagents as with the sample. 5.3 When the reaction subsides, heat gently to assist the attack and add 10 ml of nitric acid (40 %). Heat without boiling until the evolution of hydrogen ceases. Then boil gently for about 10 minutes. Rinse the walls of the beaker and watchglass wit
37、h hot water, collecting the washings in the same beaker. 5.4 Dilute to about 150200 ml with hot water and filter if necessary (Note 8.1) through a close-textured filter paper containing a small quantity of paper-pulp. Wash the filter and residue carefully eight to ten times with hot hydrochloric aci
38、d (2.5 %), collecting the filtrate and washings in a 400 ml beaker. If there is considerable residue transfer the filter and residue to a platinum crucible and dry in an oven at about 120 C. Then ignite carefully until combustion of the filter is complete (the temperature should not exceed 550 C) ta
39、king care that the filter paper does not catch alight. Cool, add 5 ml of hydrofluoric acid5), 2 ml of sulphuric acid (25 %) and finally add nitric acid (40 %) dropwise until a perfectly clear solution is obtained. Evaporate until elimination of the white sulphuric acid fumes is complete, then heat f
40、or 10 minutes at a temperature not exceeding 700 C. Allow to cool and take up with a few millilitres of hot water and 12 ml of hydrochloric acid (50 %). Heat gently, filter if necessary and add the solution obtained to the test solution. 5.5 Proceed as follows according to the magnesium content: 5.5
41、.1 For magnesium contents up to 1.5 %. Concentrate the solution to about 100 ml. Add 5 ml of ferric chloride solution (0.5 %) and mix. Transfer the solution to a 400 ml beaker containing 100 ml of sodium hydroxide solution (20 %) using the smallest possible quantity of lukewarm water for washing. Mi
42、x carefully, add 3 ml of hydrogen peroxide (100 vol.), then boil for 5 to 10 minutes. Remove from the source of heat, add 7.5 ml of potassium cyanide solution (25 %), then boil gently for 5 minutes. Dilute if necessary to about 270 ml with hot water, cover the beaker with a watchglass and heat gentl
43、y without boiling for 20 minutes. Add a small quantity of paper-pulp, mix, then filter through a close-textured filter paper. Wash the filter and residue carefully five times with hot sodium hydroxide solution (2 %) (Note 8.2). 4) It should be noted that the use of industrial methylated spirit is go
44、verned by The Methylated Spirits Regulations 1952 (SI 1952, No. 2230). 5) This refers to the usual analytical reagent grade of 40 % w/w. Licensed Copy: sheffieldun sheffieldun, na, Fri Nov 24 08:09:28 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 1728-22:1972 BSI 11-19993 5.5.2 For magnesium content
45、s over 1.5 %. Transfer the solution to a 200 ml volumetric flask, dilute to the mark and mix. Take the appropriate aliquot in accordance with the following table, transfer to a 250 ml beaker and dilute if necessary to 100 ml. Add 5 ml of ferric chloride solution (0.5 %) and mix. Transfer the solutio
46、n to a 400 ml beaker containing 70 ml of sodium hydroxide solution (20 %) using the smallest possible quantity of lukewarm water for washing. Mix carefully, add 2 ml of hydrogen peroxide (100 vol.), then boil for 5 to 10 minutes. Remove from the source of heat, add 5 ml of potassium cyanide solution
47、 (25 %), then boil gently for 5 minutes. Dilute if necessary to about 200 ml with hot water, cover the beaker with a watchglass and heat gently without boiling for 20 minutes. Add a small quantity of paper-pulp, mix, then filter through a close-textured filter paper. Wash the filter and residue care
48、fully five times with hot sodium hydroxide solution (2 %) (Note 8.2). 5.6 Open the filter over the beaker used for the hydroxide precipitation and with a jet of hot water wash the precipitate off the paper into the beaker. Wash the filter with a hot mixture of 50 ml of hydrochloric acid (20 %) and 2
49、 ml of hydroxylammonium chloride solution (2 %). Then complete the washing with hot water, taking care to keep the final volume below 80 ml. Heat to complete the dissolution of the precipitate, filter through a medium-textured filter paper, wash the filter and beaker, first with hot water then with hot hydrochloric acid (2.5 %), collecting the filtrate and washings in a 400 ml beaker. Add bromine water (saturated) in small portions until there is a persistent bromine colour, then add 3 ml in excess. Boil to remove