1、BRITISH STANDARD BS 6200-3.19.2: 1992 Sampling and analysis of iron, steel and other ferrous metals Part3: Methods of analysis Section3.19 Determination of molybdenum Subsection3.19.2 Ferromolybdenum: gravimetric methodBS6200-3.19.2:1992 This British Standard, having been prepared under the directio
2、nof the Iron and Steel Standards Policy Committee, waspublished under the authorityof the Standards Boardand comes into effect on 15June1992 BSI 09-1999 The following BSI references relate to the work on this standard: Committee reference ISM/18 Draft for comment91/44340 DC ISBN 0 580 20795 1 Commit
3、tees responsible for this British Standard The preparation of this British Standard was entrusted by the Iron and Steel Standards Policy Committee (ISM/-) to Technical Committee ISM/18, upon which the following bodies were represented: BCIRA British Steel Industry Department of Trade and Industry (L
4、aboratory of the Government Chemist) Ferro Alloys and Metals Producers Association Ministry of Defence Amendments issued since publication Amd. No. Date CommentsBS6200-3.19.2:1992 BSI 09-1999 i Contents Page Committees responsible Inside front cover Foreword ii 1 Scope 1 2 Principle 1 3 Reagents 1 4
5、 Apparatus 1 5 Sampling 1 6 Procedure 2 7 Calculation and expression of results 2 8 Test report 3 Table 1 Precision data 3 Publication(s) referred to Inside back coverBS6200-3.19.2:1992 ii BSI 09-1999 Foreword This Subsection of BS6200 has been prepared under the direction of the Iron and Steel Stan
6、dards Policy Committee and supersedes method2 for the determination of molybdenum in BSI Handbook No.19, to which it is technically equivalent. BS6200 is a multipart British Standard, covering all aspects of the sampling and analysis of iron, steel and other ferrous metals. A list of contents, toget
7、her with general information, is given in Part1. 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 oblig
8、ations. Summary of pages This document 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 i
9、nside front cover.BS6200-3.19.2:1992 BSI 09-1999 1 1 Scope This Subsection of BS6200 describes a gravimetric method for the determination of molybdenum in ferromolybdenum. The method is applicable to the range of molybdenum contents normally found in ferromolybdenum. NOTEThe titles of the publicatio
10、ns referred to in this Subsection of BS6200 are listed on the inside back cover. 2 Principle After dissolution of the test portion in acid, and separation of iron with sodium hydroxide, molybdenum is precipitated as its quinolin-8-ol compound in the presence of ethylenediaminetetra-acetic acid disod
11、ium salt and ammonium oxalate, filtered, dried and weighed as the anhydrous compound (MoO 2 (C 9 H 6 ON) 2 ). 3 Reagents During the analysis use only reagents of recognized analytical grade, and only grade3 water as specified in BS3978. 3.1 Ammonia solution, density =0.91g/ml, diluted1+1. 3.2 Ammoni
12、um oxalate 3.3 Ethylenediaminetetra-acetic acid disodium salt (EDTA.Na 2 ),100g/l solution. Dissolve10g of EDTA.Na 2in80ml of water, dilute to100ml and mix. 3.4 Hydrochloric acid, =1.16g/ml to1.18g/ml. 3.5 Hydrochloric acid, =1.16g/ml to1.18g/ml, diluted1+1. 3.6 Hydrofluoric acid,40% (m/m). 3.7 Nitr
13、ic acid, =1.42g/ml. 3.8 Nitric acid, =1.42g/ml, diluted1+3. 3.9 Quinolin-8-ol,30g/l solution. Dissolve3g of quinolin-8-ol (also known as8-hydroxyquinoline or oxine) in12ml of acetic acid, =1.048g/ml to1.050g/ml, add60ml of water and warm to approximately40 C. Add ammonia solution, =0.91g/ml, dropwis
14、e until a slight permanent precipitate is formed. Just redissolve the precipitate with dropwise additions of acetic acid =1.048g/ml to1.050g/ml, cool, dilute to100ml and mix. 3.10 Sodium hydroxide,460g to480g per litre solution. To a1l polyethylene beaker, containing500ml of water, add slowly, cauti
15、ously and with cooling and stirring,460g to480g of sodium hydroxide. Cool, dilute to1l and store in a stoppered polyethylene bottle. 3.11 Sulfuric acid, =1.84g/ml, diluted1+1. To80ml of water add cautiously, with cooling and stirring,100ml of sulfuric acid, =1.84g/ml, cool, dilute to200ml and mix. 4
16、 Apparatus 4.1 Ordinary laboratory apparatus 4.2 Volumetric glassware, in accordance with class A of BS1792. 4.3 Polytetrafluoroethylene beakers 4.4 pH meter 4.5 Crucibles, sintered glass, pore size index4m to10 m, in accordance with BS1752. Use the following procedures for handling and cooling sint
17、ered glass crucibles. a) Before use, wash the crucible several times with hot nitric acid(3.8) and finally with water, using gentle suction. b) After suction washing, wash the outer crucible wall with hot water, dry on filter paper and from that stage do not touch with bare hands. Preferably, handle
18、 the crucible with tweezers or tongs or for a minimum period in a gloved hand. Dry at125 C. c) After oven drying, place empty crucibles or those containing the quinolin-8-ol precipitate in an efficient desiccator and allow to stand at balance room temperature for1h before weighing. Repeat the drying
19、 and cooling until the weight is constant. d) After use, remove the bulk of precipitate with a jet of water, place the crucible in a small beaker containing5ml to10ml of sulfuric acid(3.11) and fill the crucible with nitric acid(3.7). Heat the beaker until fumes of sulfur trioxide are evolved, cool,
20、 remove the crucible and pass approximately100ml of hot water through the sinter under gentle suction. Treat the washed crucible as inb) andc) above. 4.6 Funnel, modified for slow addition by drawing down the stem of a75mm funnel to produce a jet size of approximately1mm diameter. 5 Sampling Carry o
21、ut sampling in accordance with BS1837. NOTEBS6200-2, which will supersede BS1837, is currently in preparation. On its publication this Subsection will be amended to include sampling in accordance with BS6200-2.BS6200-3.19.2:1992 2 BSI 09-1999 6 Procedure 6.1 Test portion Weigh to the nearest0.001g,
22、a test portion of1g for75% (m/m) ferromolybdenum or a test portion of1g for50% (m/m) ferromolybdenum. 6.2 Determination 6.2.1 Preparation of the test solution Place the test portion in a150ml polytetrafluoroethylene beaker(4.3). Add10ml of sulfuric acid(3.11) and warm. Add nitric acid(3.7) dropwise
23、to dissolve the test portion and then0.5ml in excess. Add5ml of hydrofluoric acid(3.6) and evaporate until fumes of sulfur trioxide are evolved, and continue fuming for15min. Cool, add5ml of hydrochloric acid(3.4) and5ml of nitric acid(3.7), warm for10min and dilute to approximately50ml. 6.2.2 Separ
24、ation of iron To a tall form beaker of650ml to800ml capacity, add50ml of sodium hydroxide solution(3.10) and50ml of water, heat to boiling and place a funnel(4.6) in the mouth of the beaker. Transfer the test portion solution slowly via the funnel into the beaker, maintaining the sodium hydroxide so
25、lution in the boiling state. Rinse the polytetrafluoroethylene beaker with hot water at85 C to90 C and transfer to the funnel. Rinse the funnel and upper surface of the tall form beaker, boil the solution for2min to3min, dilute to approximately450ml and cool. Transfer to a500ml volumetric flask, dil
26、ute to the mark and mix thoroughly. Dry the original tall form beaker, transfer the solution from the volumetric flask back to it and allow to stand for15min to20min. Filter a portion of the solution through a dry rapid and hardened filter paper and transfer a100ml aliquot to a400ml beaker. NOTEWhat
27、man No.541filter paper has been found to be suitable. 6.2.3 Precipitation of molybdenum with quinolin-8-ol Dilute the aliquot to approximately200ml, add10ml of EDTA.Na 2solution(3.3) and3g of ammonium oxalate(3.2). Warm gently to dissolve the ammonium oxalate, cool to room temperature and, using the
28、 pH meter(4.4), adjust to pH4.0 with hydrochloric acid(3.5) and ammonia solution(3.1). Heat the solution to boiling and continue the boiling during the addition of20ml of quinolin-8-ol solution(3.9). IMPORTANT NOTE. It is essential that this operation is carried out in boiling solution. When precipi
29、tation is made in a solution below boiling point the precipitate is more difficult to wash and initially gives high recoveries; if dried to constant weight (perhaps2days to3days) it sometimes gives low recoveries. 6.2.4 Filtration and weighing of the molybdenum quinolin-8-ol precipitate Allow to sta
30、nd for5min to10min at80 C to90 C with occasional stirring and filter through a dried and weighed sintered glass crucible(4.5), using gentle suction. During filtration, add the solution at such a rate that not more than half the crucible is filled at any time. This procedure facilitates the efficient
31、 washing of the crucible and frees the precipitate of soluble salts. Completely remove the precipitate from the walls of the beaker using a rubber-tipped glass rod and transfer to the crucible. Then wash the precipitate in the crucible with approximately100ml of hot water at80 C to90 C. Dry at125 C
32、overnight, cool and weigh. Redry to constant mass. The gain is the mass of anhydrous molybdenum quinolin-8-ol compound, MoO 2 (C 9 H 6 ON) 2 . 7 Calculation and expression of results 7.1 Calculation Calculate the molybdenum content Mo, expressed as a percentage by mass, from the equation: where 7.2
33、Precision A planned trial of this method was carried out by seven analysts, each from a different laboratory; five tests were carried out by each analyst on each of two samples. From the results obtained, the95% confidence limits(2s) have been calculated in accordance with BS5497-1 and are given in
34、Table 1. The difference between two single results found on identical material by one analyst using the same apparatus within a short time interval will exceed the repeatability r, on average, not more than once in20cases in the normal and correct operation of the method. m is the mass of the test p
35、ortion (in g); m 1 is the mass of the empty dried crucible (ing); m 2 is the final stable mass of the crucible and precipitate (in g); V a is the volume of the aliquot (in ml). Mo 23.05 m 2 m 1 () 500 mV a - =BS6200-3.19.2:1992 BSI 09-1999 3 Table 1 Precision data The difference between two single a
36、nd independent results found by two operators working in different laboratories on identical test material will exceed the reproducibility R, on average, not more than once in20 cases in the normal and correct operation of the method. 8 Test report The test report shall include the following informa
37、tion: a) all information necessary for the identification of the sample, the laboratory and the date of analysis; b) the method used, by reference to this Subsection of BS6200; c) the results, and the form in which they are expressed; d) any unusual features noted during the determination; e) any op
38、eration not specified in this British Standard or any optional operation which may have influenced the results. Alloy type Molybdenum Repeatability r Reproducibility R % (m/m) 50% ferromolybdenum 50.33 0.255 0.339 75% ferromolybdenum 75.34 0.283 0.3684 blankBS6200-3.19.2:1992 BSI 09-1999 Publication
39、(s) referred to BS1752, Specification for laboratory sintered or fritted filters including porosity grading. BS1792, Specification for one-mark volumetric flasks. BS1837, Methods for the sampling of iron, steel, permanent magnet alloys and ferro-alloys. BS3978, Specification for water for laboratory
40、 use. BS5497, Precision of test methods. BS5497-1, Guide for the determination of repeatability and reproducibility for a standard test method by inter-laboratory tests. BS6200, Sampling and analysis of iron, steel and other ferrous metals. BS6200-1, Introduction and contents 1) . BS6200-2, Methods
41、of sampling and sample preparation 2) . BSI Handbook No.19, Methods for the sampling and analysis of iron, steel and other ferrous metals 1) . 1) Referred to in the foreword only. 2) In preparation.BS 6200-3.19.2: 1992 BSI 389 Chiswick High Road London W4 4AL BSIBritishStandardsInstitution BSI is th
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