1、BRITISH STANDARD BS 6200-3.19.3: 1992 Sampling and analysis of iron, steel and other ferrous metals Part 3: Methods of analysis Section 3.19: Determination of molybdenum Subsection 3.19.3: Molybdenum oxide and high grade molybdenite ores:gravimetric methodBS6200-3.19.3:1992 This British Standard, ha
2、ving been prepared under the directionof the Iron and SteelStandards Policy Committee, was published underthe authority of theStandards Board andcomes into effect on 15June1992 BSI 09-1999 The following BSI references relate to the work on this standard: Committee reference ISM/18 Draft for comment9
3、1/44341 DC ISBN 0 580 20796 X Committees 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
4、 Department of Trade and Industry (Laboratory of the Government Chemist) Ferro Alloys and Metals Producers Association Ministry of Defence Amendments issued since publication Amd. No. Date CommentsBS6200-3.19.3:1992 BSI 09-1999 i Contents Page Committees responsible Inside front cover Foreword ii 1
5、Scope 1 2 Principle 1 3 Reagents 1 4 Apparatus 1 5 Sampling 1 6 Procedure 1 7 Calculation and expression of results 2 8 Test report 3 Table 1 Precision data 2 Publication(s) referred to Inside back coverBS6200-3.19.3:1992 ii BSI 09-1999 Foreword This Subsection of BS6200 has been prepared under the
6、direction of the Iron and Steel Standards Policy Committee and supersedes method3 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 ferro
7、us metals. A list of contents, together 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 its
8、elf confer immunity from legal obligations. 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 indic
9、ated in the amendment table on the inside front cover.BS6200-3.19.3:1992 BSI 09-1999 1 1 Scope This Subsection of BS6200 describes a gravimetric method for the determination of molybdenum in molybdenum oxide and high grade molybdenite ores. The method is applicable to the range of molybdenum content
10、s normally found in these materials. NOTEThe titles of the publications referred to in this Subsection of BS6200 are listed on the inside back cover. 2 Principle After dissolution of the test portion in acid, molybdenum is precipitated as its quinolin-8-ol compound in the presence of ethylenediamine
11、tetra-acetic acid disodium 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. 3
12、.2 Ammonia solution, =0.91g/ml, diluted1+1. 3.3 Ammonium oxalate 3.4 Ethylenediaminetetra-acetic acid disodium salt (EDTA.Na 2 ),100g/l solution. Dissolve10g of EDTA.Na 2in80 ml of water, dilute to100ml and mix. 3.5 Hydrochloric acid, =1.16g/ml to1.18g/ml. 3.6 Hydrochloric acid =1.16g/ml to1.18g/ml,
13、 diluted1+1. 3.7 Hydrofluoric acid, 40% (m/m). 3.8 Nitric acid, = 1.42g/ml. 3.9 Nitric acid, = 1.42g/ml, diluted1+3. 3.10 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 a
14、pproximately40 C. Add ammonia solution(3.1) dropwise 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. 3.11 Sulfuric acid, =1.84g/ml, diluted1+1. To80ml of water add cautiousl
15、y, with cooling and stirring,100ml of sulfuric acid, =1.84g/ml, cool, dilute to200ml and mix. 4 Apparatus 4.1 Ordinary laboratory apparatus 4.2 Volumetric glassware, in accordance with classA of BS1792. 4.3 Polytetrafluoroethylene beakers 4.4 pH meter 4.5 Crucibles, sintered glass, pore size index4m
16、 to10m, in accordance with BS1752. Use the following procedures for handling and cooling sintered glass crucibles. a) Before use, wash the crucible several times with hot nitric acid(3.9) and finally with water, using gentle suction. b) After suction washing, wash the outer crucible wall with hot wa
17、ter, dry on filter paper and from that stage do not touch with bare hands. Preferably, handle 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 desic
18、cator and allow to stand at balance room temperature for1h before weighing. Repeat the drying 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 cruc
19、ible with nitric acid(3.8). Heat the beaker until fumes of sulfur trioxide are evolved, cool, remove the crucible and pass approximately100ml of hot water through the sinter under gentle suction. Treat the washed crucible as in b) and c) above. 5 Sampling Carry out sampling in accordance with accept
20、ed practice. NOTESuitable procedures will be included in BS6200-2 which is currently in preparation. On its publication this Subsection will be amended to include sampling in accordance with BS6200-2. 6 Procedure 6.1 Test portion Weigh, to the nearest0.001g, a test portion of1.0g. 6.2 Determination
21、6.2.1 Preparation of the test solution Place the test portion in a150ml polytetrafluoroethylene beaker(4.3). Add10ml of sulfuric acid(3.11),5ml of nitric acid(3.8) and5ml of hydrofluoric acid(3.7). Evaporate until fumes of sulfur trioxide are evolved, and continue fuming for15min. Cool, add5ml of hy
22、drochloric acid(3.5) and5ml of nitric acid(3.8), warm for10min, and dilute to approximately50ml.BS6200-3.19.3:1992 2 BSI 09-1999 Add10ml of EDTA.Na 2solution(3.4), neutralize with ammonia solution(3.1) then add5ml excess. Heat at50 C to60 C for15min then cool. Transfer to a500ml volumetric flask, di
23、lute to the mark and mix thoroughly. If insoluble carbon is present at this stage, filter through a dry filter paper into a dry beaker. 6.2.2 Precipitation of molybdenum with quinolin-8-ol Transfer a100ml aliquot to a400ml beaker, dilute to approximately200ml, add3g of ammonium oxalate(3.3) and warm
24、 gently to dissolve. Cool to room temperature and, using the pH meter(4.4), adjust to pH4.0 with hydrochloric acid(3.6) and ammonia solution(3.2). Heat to70 C to80 C for10min then allow to stand at room temperature for not less than2h. If calcium is present the calcium oxalate will precipitate. Filt
25、er through a small filter paper and wash with water, adding the washings to the solution to attain a final volume of approximately250ml. NOTEWhatman No.540 filter paper has been found to be suitable. Heat the solution to boiling and continue the boiling during the addition of20ml of quinolin-8-ol so
26、lution(3.10). IMPORTANT NOTE. It is essential that this operation is carried out in boiling solution. When precipitation 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 so
27、metimes gives low recoveries. 6.2.3 Filtration and weighing of the molybdenum quinolin-8-ol precipitate Allow to stand for5min to10min at80 C to90 C with occasional stirring and filter through a dried and weighed sintered glass crucible(4.5) using gentle suction. Completely remove the precipitate fr
28、om the walls of the beaker using a rubber-tipped glass rod and transfer to the crucible. Then wash theprecipitate in the crucible with approximately100ml of hot water at80 C to90 C. During filtration, add the solution at such a rate that not more than half the crucible is filled at any time. This pr
29、ocedure facilitates the efficient washing of the crucible and frees the precipitate of soluble salts. Dry at125 C overnight, cool and weigh. Re-dry 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.
30、1 Calculation Calculate the molybdenum content Mo, expressed as a percentage by mass, from the equation: 7.2 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 resu
31、lts obtained, the95% confidence limits(2s) have been calculated in accordance with BS5497-1 and are given in 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
32、, not more than once in20cases in the normal and correct operation of the method. The difference between two single and 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
33、 in the normal and correct operation of the method. Table 1 Precision data where m is the mass of the test portion (in g); m 1 is the mass of the empty dried crucible (ing); m 2 is the final stable weight of the crucible and precipitate (in g); V a is the volume of the aliquot (in ml). Mo 23.05 m 2
34、m 1 ()500 m V a - = Material Molybdenum Repeatability r Reproducibility R Molybdenum oxide “pure” “crude” % (m/m) 66.51 59.54 0.271 0.359 0.396 0.410BS6200-3.19.3:1992 BSI 09-1999 3 8 Test report The test report shall include the following information: a) all information necessary for the identifica
35、tion 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 operation not specified in this British Standard or any
36、 optional operation which may have influenced the results.4 blankBS6200-3.19.3:1992 BSI 09-1999 Publication(s) referred to BS1752, Specification for laboratory sintered or fritted filters including porosity grading. BS1792, Specification for one-mark volumetric flasks. BS3978, Specification for wate
37、r for laboratory 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) . BS
38、6200-2, Methods 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 6200-3.19.3: 1992 BSI 389 Chiswick High Road London W4 4AL BSIBritishStandardsInsti
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