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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 method Licensed Copy: sheffieldun sheffieldun, na
2、, Wed Dec 06 14:54:09 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6200-3.19.3:1992 This British Standard, having been prepared under the direction of the Iron and Steel Standards Policy Committee, was published under the authority of the Standards Board and comes into effect on 15 June 1992 BSI 09
3、-1999 The following BSI references relate to the work on this standard: Committee reference ISM/18 Draft for comment 91/44341 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
4、 (ISM/-) to Technical Committee ISM/18, upon which the following bodies were represented: BCIRA British Steel Industry 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
5、.DateComments Licensed Copy: sheffieldun sheffieldun, na, Wed Dec 06 14:54:09 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6200-3.19.3:1992 BSI 09-1999i Contents Page Committees responsibleInside front cover Forewordii 1Scope1 2Principle1 3Reagents1 4Apparatus1 5Sampling1 6Procedure1 7Calculation a
6、nd expression of results2 8Test report3 Table 1 Precision data2 Publication(s) referred toInside back cover Licensed Copy: sheffieldun sheffieldun, na, Wed Dec 06 14:54:09 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6200-3.19.3:1992 ii BSI 09-1999 Foreword This Subsection of BS 6200 has been prepa
7、red under the direction of the Iron and Steel Standards Policy Committee and supersedes method 3 for the determination of molybdenum in BSI Handbook No. 19, to which it is technically equivalent. BS 6200 is a multipart British Standard, covering all aspects of the sampling and analysis of iron, stee
8、l and other ferrous metals. A list of contents, together with general information, is given in Part 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 Standa
9、rd does not of itself confer immunity from legal obligations. Summary of pages This 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 incorporat
10、ed. This will be indicated in the amendment table on the inside front cover. Licensed Copy: sheffieldun sheffieldun, na, Wed Dec 06 14:54:09 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6200-3.19.3:1992 BSI 09-19991 1 Scope This Subsection of BS 6200 describes a gravimetric method for the determina
11、tion of molybdenum in molybdenum oxide and high grade molybdenite ores. The method is applicable to the range of molybdenum contents normally found in these materials. NOTEThe titles of the publications referred to in this Subsection of BS 6200 are listed on the inside back cover. 2 Principle After
12、dissolution of the test portion in acid, molybdenum is precipitated as its quinolin-8-ol compound in the presence of ethylenediaminetetra-acetic acid disodium salt and ammonium oxalate, filtered, dried and weighed as the anhydrous compound, MoO2(C9H6ON)2. 3 Reagents During the analysis use only reag
13、ents of recognized analytical grade and only grade 3 water as specified in BS 3978. 3.1 Ammonia solution, density = 0.91 g/ml. 3.2 Ammonia solution, = 0.91 g/ml, diluted 1 + 1. 3.3 Ammonium oxalate 3.4 Ethylenediaminetetra-acetic acid disodium salt (EDTA.Na2), 100 g/l solution. Dissolve 10 g of EDTA
14、.Na2 in 80 ml of water, dilute to 100 ml and mix. 3.5 Hydrochloric acid, = 1.16 g/ml to 1.18 g/ml. 3.6 Hydrochloric acid = 1.16 g/ml to 1.18 g/ml, diluted 1 + 1. 3.7 Hydrofluoric acid, 40 % (m/m). 3.8 Nitric acid, = 1.42 g/ml. 3.9 Nitric acid, = 1.42 g/ml, diluted 1 + 3. 3.10 Quinolin-8-ol, 30 g/l s
15、olution. Dissolve 3 g of quinolin-8-ol (also known as 8-hydroxyquinoline or oxine) in 12 ml of acetic acid, = 1.048 g/ml to 1.050 g/ml, add 60 ml of water and warm to approximately 40 C. Add ammonia solution (3.1) dropwise until a slight permanent precipitate is formed. Just redissolve the precipita
16、te with dropwise additions of acetic acid, = 1.048 g/ml to 1.050 g/ml, cool, dilute to 100 ml and mix. 3.11 Sulfuric acid, = 1.84 g/ml, diluted 1 + 1. To 80 ml of water add cautiously, with cooling and stirring, 100 ml of sulfuric acid, = 1.84 g/ml, cool, dilute to 200 ml and mix. 4 Apparatus 4.1 Or
17、dinary laboratory apparatus 4.2 Volumetric glassware, in accordance with class A of BS 1792. 4.3 Polytetrafluoroethylene beakers 4.4 pH meter 4.5 Crucibles, sintered glass, pore size index 4 m to 10 m, in accordance with BS 1752. Use the following procedures for handling and cooling sintered glass c
18、rucibles. 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 water, dry on filter paper and from that stage do not touch with bare hands. Preferably, handle the crucib
19、le with tweezers or tongs or for a minimum period in a gloved hand. Dry at 125 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 for 1 h before weighing. Repeat the drying and coo
20、ling 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 containing 5 ml to 10 ml of sulfuric acid (3.11) and fill the crucible with nitric acid (3.8). Heat the beaker until fumes of sulfur trioxide are evolved, cool, r
21、emove the crucible and pass approximately 100 ml 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 accepted practice. NOTESuitable procedures will be included in BS 6200-2 which is currently in prep
22、aration. On its publication this Subsection will be amended to include sampling in accordance with BS 6200-2. 6 Procedure 6.1 Test portion Weigh, to the nearest 0.001 g, a test portion of 1.0 g. 6.2 Determination 6.2.1 Preparation of the test solution Place the test portion in a 150 ml polytetrafluo
23、roethylene beaker (4.3). Add 10 ml of sulfuric acid (3.11), 5 ml of nitric acid (3.8) and 5 ml of hydrofluoric acid (3.7). Evaporate until fumes of sulfur trioxide are evolved, and continue fuming for 15 min. Cool, add 5 ml of hydrochloric acid (3.5) and 5 ml of nitric acid (3.8), warm for 10 min, a
24、nd dilute to approximately 50 ml. Licensed Copy: sheffieldun sheffieldun, na, Wed Dec 06 14:54:09 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6200-3.19.3:1992 2 BSI 09-1999 Add 10 ml of EDTA.Na2 solution (3.4), neutralize with ammonia solution (3.1) then add 5 ml excess. Heat at 50 C to 60 C for 1
25、5 min then cool. Transfer to a 500 ml volumetric flask, dilute 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 a 100 ml aliquot to a 400 ml beaker, dilute
26、to approximately 200 ml, add 3 g of ammonium oxalate (3.3) and warm gently to dissolve. Cool to room temperature and, using the pH meter (4.4), adjust to pH 4.0 with hydrochloric acid (3.6) and ammonia solution (3.2). Heat to 70 C to 80 C for 10 min then allow to stand at room temperature for not le
27、ss than 2 h. If calcium is present the calcium oxalate will precipitate. Filter through a small filter paper and wash with water, adding the washings to the solution to attain a final volume of approximately 250 ml. NOTEWhatman No. 540 filter paper has been found to be suitable. Heat the solution to
28、 boiling and continue the boiling during the addition of 20 ml of quinolin-8-ol solution (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 initiall
29、y gives high recoveries; if dried to constant weight, (perhaps 2 days to 3 days), it sometimes gives low recoveries. 6.2.3 Filtration and weighing of the molybdenum quinolin-8-ol precipitate Allow to stand for 5 min to 10 min at 80 C to 90 C with occasional stirring and filter through a dried and we
30、ighed sintered glass crucible (4.5) using gentle suction. 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 approximately 100 ml of hot water at 80 C to 90 C. During filtration,
31、add the solution at such a rate that not more than half the crucible is filled at any time. This procedure facilitates the efficient washing of the crucible and frees the precipitate of soluble salts. Dry at 125 C overnight, cool and weigh. Re-dry to constant mass. The gain is the mass of anhydrous
32、molybdenum quinolin-8-ol compound, MoO2(C9H6ON)2. 7 Calculation and expression of results 7.1 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 l
33、aboratory; five tests were carried out by each analyst on each of two samples. From the results obtained, the 95 % confidence limits (2s) have been calculated in accordance with BS 5497-1 and are given in Table 1. The difference between two single results found on identical material by one analyst u
34、sing the same apparatus within a short time interval will exceed the repeatability r, on average, not more than once in 20 cases 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 id
35、entical test material will exceed the reproducibility R, on average, not more than once in 20 cases in the normal and correct operation of the method. Table 1 Precision data where mis the mass of the test portion (in g); m1is the mass of the empty dried crucible (in g); m2is the final stable weight
36、of the crucible and precipitate (in g); Vais the volume of the aliquot (in ml). Mo 23.05 m2m1()500 m Va - -= MaterialMolybdenumRepeatability rReproducibility R Molybdenum oxide “pure” “crude” % (m/m) 66.51 59.54 0.271 0.359 0.396 0.410 Licensed Copy: sheffieldun sheffieldun, na, Wed Dec 06 14:54:09
37、GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6200-3.19.3:1992 BSI 09-19993 8 Test report The test report shall include the following information: 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 Subs
38、ection of BS 6200; 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 optional operation which may have influenced the results. Licensed Copy: sheffieldun sheffieldun, na, We
39、d Dec 06 14:54:09 GMT+00:00 2006, Uncontrolled Copy, (c) BSI 4 blank Licensed Copy: sheffieldun sheffieldun, na, Wed Dec 06 14:54:09 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6200-3.19.3:1992 BSI 09-1999 Publication(s) referred to BS 1752, Specification for laboratory sintered or fritted filters
40、 including porosity grading. BS 1792, Specification for one-mark volumetric flasks. BS 3978, Specification for water for laboratory use. BS 5497, Precision of test methods. BS 5497-1, Guide for the determination of repeatability and reproducibility for a standard test method by inter-laboratory test
41、s. BS 6200, Sampling and analysis of iron, steel and other ferrous metals. BS 6200-1, Introduction and contents1). BS 6200-2, Methods of sampling and sample preparation2). BSI Handbook No. 19, Methods for the sampling and analysis of iron, steel and other ferrous metals1). 1) Referred to in the fore
42、word only. 2) In preparation. Licensed Copy: sheffieldun sheffieldun, na, Wed Dec 06 14:54:09 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6200-3.19.3: 1992 BSI 389 Chiswick High Road London W4 4AL BSI British Standards Institution BSI is the independent national body responsible for preparing Brit
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