《ISO-5931-2000.pdf》由会员分享，可在线阅读，更多相关《ISO-5931-2000.pdf（14页珍藏版）》请在三一文库上搜索。
1、INTERNATIONAL STANDARD ISO 5931 First edition 2000-08-15 Reference number ISO 5931:2000(E) ISO 2000 Carbonaceous materials used in the production of aluminium Calcined coke and calcined carbon products Determination of total sulfur by the Eschka method Produits carbons utiliss pour la production de
2、laluminium Coke calcin et produits carbons calcins Dosage du soufre total par la mthode Eschka ISO 5931:2000(E) ii ISO 2000 All rights reserved PDF disclaimer This PDF file may contain embedded typefaces. In accordance with Adobes licensing policy, this file may be printed or viewed but shall not be
3、 edited unless the typefaces which are embedded are licensed to and installed on the computer performing the editing. In downloading this file, parties accept therein the responsibility of not infringing Adobes licensing policy. The ISO Central Secretariat accepts no liability in this area. Adobe is
4、 a trademark of Adobe Systems Incorporated. Details of the software products used to create this PDF file can be found in the General Info relative to the file; the PDF-creation parameters were optimized for printing. Every care has been taken to ensure that the file is suitable for use by ISO membe
5、r bodies. In the unlikely event that a problem relating to it is found, please inform the Central Secretariat at the address given below. ISO 2000 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, elec- tronic or m
6、echanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or ISOs mem- ber body in the country of the requester. ISO copyright office Case postale 56 CH-1211 Geneva 20 Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail copyrightiso.ch Web ww
7、w.iso.ch Printed in Switzerland ISO 5931:2000(E) ISO 2000 All rights reserved iii ContentsPage 1Scope .1 2Normative references .1 3Principle 1 4Reagents 1 5Apparatus .2 6Preparation of test sample 2 7Procedure .3 8Expression of results 4 9Precision .5 10Test report 5 Annex ADerivation of factors use
8、d in the calculation in clause 8 .6 Bibliography.7 ISO 5931:2000(E) iv ISO 2000 All rights reserved Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally
9、carried out through ISO technical com- mittees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liai- son with ISO, also take part in th
10、e work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 3. Draft International Standards adopted by the technic
11、al committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. Attention is drawn to the possibility that some of the elements of this International Standard may be the subject of patent r
12、ights. ISO shall not be held responsible for identifying any or all such patent rights. International Standard ISO 5931 was prepared by Technical Committee ISO/TC 47,Chemistry, Subcommittee SC 7, Aluminium oxide, cryolite, aluminium fluoride, sodium fluoride, carbonaceous products for the aluminium
13、industry. Annex A of this International Standard is for information only. ISO 5931:2000(E) ISO 2000 All rights reserved v Introduction Instrumental methods for a more rapid determination of total sulfur are now available. lf such a method is to be used, it is important to demonstrate that the method
14、 is free from bias when compared to this reference method and will give levels of repeatability and reproducibility which are the same as, or better than, those quoted for this reference method (see clause 9). INTERNATIONAL STANDARDISO 5931:2000(E) ISO 2000 All rights reserved 1 Carbonaceous materia
15、ls used in the production of aluminium Calcined coke and calcined carbon products Determination of total sulfur by the Eschka method 1Scope This International Standard specifies a reference method for determining the total sulfur content of calcined coke and calcined carbon products by the Eschka me
16、thod, provided that they contain a minimum ofby mass and prefer- ably less thanby mass of sulfur. 2Normative references The following normative documents contain provisions which, through reference in this text, constitute provisions of this International Standard. For dated references, subsequent a
17、mendments to, or revisions of, any of these publica- tions do not apply. However, parties to agreements based on this International Standard are encouraged to investi- gate the possibility of applying the most recent editions of the normative documents indicated below. For undated references, the la
18、test edition of the normative document referred to applies. Members of ISO and IEC maintain registers of currently valid International Standards. ISO 4787:1984,Laboratory glassware Volumetric glassware Methods for use and testing of capacity. ISO 4788:1980,Laboratory glassware Graduated measuring cy
19、linders. ISO 5069-2:1983,Brown coals and lignites Principles of sampling Part 2: Sample preparation for determination of moisture content and for general analysis. ISO 6375:1980,Carbonaceous materials for the production of aluminium Coke for electrodes Sampling. 3Principle A test portion is ignited
20、in intimate contact with Eschka mixture in an oxidizing atmosphere to remove combustible matter and to convert the sulfur to sulfate. The sulfate is then extracted using a hydrochloric acid solution and the sul- fur content, in the form of sulfate, is determined gravimetrically by precipitation of t
21、he sulfate with barium chloride. 4Reagents WARNING Care should be exercised when handling the reagents, many of which are toxic and corrosive. During the analysis, unless otherwise stated, use only reagents of recognized analytical grade and only distilled water or water of equivalent purity. 4.1Esc
22、hka mixture. Mix two parts by mass of light, calicined magnesium oxide with one part by mass of anhydrous sodium (or potas- sium) carbonate. Pass the mixture entirely through a test sieve ofnominal size of openings. 4.2Hydrochloric acid, concentrated,approximately, approximatelyby mass. 0,1 % 4 % 21
23、2m 1,18 g/ml36 % ISO 5931:2000(E) 2 ISO 2000 All rights reserved 4.3Potassium sulfate, solution. Weigh, to the nearest, aboutof potassium sulfate, previously dried at a temperature ofto. Dissolve in water and dilute to. 4.4Barium chloride, approximatelysolution. Dissolveof barium chloride dihydrate
24、in water and dilute to. Filter before use through a close-textured, dou- bly acid-washed filter-paper or filter-paper pad (see 5.8). 4.5Methyl red, indicator solution. Dissolveof 2-(4-dimethylaminophenylazo) benzoic acid, sodium salt (methyl red) inof water. 4.6Ammonia, concentrated solution, no les
25、s thanby mass. 4.7Silver nitrate,solution. Dissolveof silver nitrate in water and dilute to. Store in a dark glass bottle. 5Apparatus 5.1Analytical balance, capable of weighing to the nearest. 5.2Graduated glassware, complying with the requirements for class A in ISO 4788 and in accordance with ISO
26、4787. 5.3Electrically heated muffle furnace, capable of being maintained at. The ventilation through the muffle furnace shall be such as to give about five air changes per minute. 5.4Crucible, of platinum, silica or glazed porcelain, of approximatelycapacity. 5.5Flat plate,thick, of silica (or other
27、 suitable refractory material), which fits easily into the muffle furnace (5.3). 5.6Gooch crucible, with a maximum pore size of, of glazed porcelain or sintered glass. Before commencing the filtration, dry the Gooch crucible and pad forin the air oven (5.7) atand weigh it to the nearest. 5.7Air oven
28、, capable of being maintained at. 5.8Filter paper or filter-paper pad, doubly acid-washed, ashless, close-textured and/or medium-textured. To prepare the filter-paper pad, shake doubly acid-washed filter-paper clippings (cut into pieces of approximately ) with water in a bottle until the paper is th
29、oroughly disintegrated. Place a porcelain filter cone ofin a funnel. Close the stem of the funnel with a finger and add water until the cone is immersed and the funnel stem is full. Shake sufficient paper pulp to form a padthick onto the cone and level it with a flat-ended glass rod. Allow the exces
30、s water to drain off by removing the finger from the stem and as drainage ceases, lightly tamp the pad around the edges with the glass rod. Finally wash with water to render the filter ready for use. 5.9Dessicator. 0,1 mg2 g105 C 110 C 1 l 85 g/l 100 g1 l 1 g1 l 25 % 17 g/l 17 g1 l 0,1 mg (80025) C
31、25 ml 6 mm 7m 1 h(13010) C 0,1 mg (13010) C 1 cm225 mm 75 mm 5 mm ISO 5931:2000(E) ISO 2000 All rights reserved 3 6Preparation of test sample The test sample is the representative sample prepared in accordance with ISO 6375. Expose the test sample, dis- tributed in a thin layer, to the laboratory at
32、mosphere for the minimum time required for the moisture content to reach approximate equilibrium. Before commencing the determination, thoroughly mix the test sample for at least, preferably by mechanical means. lf the results are to be calculated other than on an “air-dried” basis (see clause 8), t
33、hen, after weighing the test por- tion (see 7.1), determine the moisture content using another portion of the test sample. 7Procedure 7.1Test portion Take two test portions of, each weighed to the nearest. Carry out the procedure given in 7.2 to 7.6 on each test portion. 7.2Loading the crucible Weig
34、hof the Eschka mixture (4.1). Divide this mixture into three portions,and, and weigh each to the nearest. For this purpose, it may be convenient to calibrate two glass tubes for theandpor- tions. Uniformly cover the bottom of the crucible with theportion of the Eschka mixture. In another suitable ve
35、ssel, mix the test portion thoroughly with theportion of the Eschka mixture. Transfer this mixture to thecrucible. Level the contents by tapping the crucible gently on the laboratory benchtop and cover the contents uniformly with portion of the Eschka mixture. NOTEThe layer of Eschka mixture below t
36、he test portion mixture reduces attack on the porcelain surface, so that the extraction of sulfate with hot water is complete even when the surface deteriorates. 7.3Ignition Place the loaded crucible (or crucibles) on the cold insulating plate (5.5) and insert into the muffle furnace (5.3) main- tai
37、ned at, and heat for at least. Withdraw the crucible (or crucibles) and allow to cool. NOTEThe cracking of porcelain crucibles can be prevented, if they are slowly cooled by insertion into supports of light porous firebrick upon removal from the muffle furnace. 7.4Recovering the residue Transfer the
38、 ignited mixture from the crucible to abeaker containingtoof water. lf unburnt parti- cles are present, stop the determination and repeat the test. Wash the crucible thoroughly with aboutof hot water, then add the washings to the contents of the beaker. 7.5Extraction Place a watch-glass on the beake
39、r and, tilting the watch-glass to leave an opening, carefully add enough hydrochloric acid (4.2) to dissolve the solid matter (will normally be required) while warming the contents of the beaker to enhance solution. Boil forto expel carbon dioxide. Filter (5.8) and collect the filtrate in aconical b
40、eaker. NOTEA medium-textured, doubly acid-washed filter-paper or a filter-paper pad can be used to speed filtration. 1 min 1 g0,1 mg 4 g0,5 g 1,0 g2,5 g 0,1 mg0,5 g1,0 g 0,5 g 2,5 g25 ml 1,0 g 800 C 3 h 400 ml25 ml30 ml 50 ml 17 ml 5 min400 ml ISO 5931:2000(E) 4 ISO 2000 All rights reserved Wash the
41、 filter with fiveportions of hot water. Add 2 or 3 drops of the methyl red indicator solution (4.5) to the combined filtrate and washings, and then cautiously add the ammonia solution (4.6) until the colour of the indicator changes and a trace of precipitate is formed. Add just enough hydrochloric a
42、cid (4.2) to redissolve the precipitate and then addin excess. 7.6Precipitation of barium sulfate After extraction, dilute the solution, if necessary, to approximatelyand cover the beaker containing the solution with a watch-glass. Heat the covered beaker until the solution boils then reduce the hea
43、t slightly until the solution ceases to boil. Using a pipette, add, over a period of,of the cold barium sulfate solution to the middle of the hot, stirred solution. Keep the solution just below the boiling point for. Filter the solution using one of the following techniques: a)by gravity through an
44、ashless, close-textured, doubly acid-washed filter-paper (see 5.8) of diameterto . Carefully fold the filter-paper and fit it into a fluted, long-stemmedfunnel, so that the stem remains full of liquid during the filtration; b)by gravity through a filter-paper pad prepared from ashless, doubly acid-w
45、ashed filter-paper (see 5.8); c)by suction through a pad of filtration mineral fibre in a Gooch crucible (5.6). Wash the precipitate with hot water, using no more than, until the lastof the washings give no more than a faint opalescence with the silver nitrate solution (4.7). lf technique a) or b) i
46、s used, place the wet filter-paper or pad in the previously ignited and weighed crucible (5.4) on the cold flat plate (5.5). If technique b) is used, after transferring the filter-paper pad to the crucible, wipe the funnel successively with two halves of an ashless filter-paper and place this paper
47、in the crucible with the pad. Insert the crucible slowly into the muffle furnace (5.3) maintained at, and heat for. Cool in a desiccator (5.9) and reweigh to the nearest . lf technique c) is used, dry the Gooch crucible (5.6) and pad for 1 h in the air oven (5.7) at, cool in a desicca- tor (5.9) and
48、 reweigh to the nearest. 7.7Blank Carry out a blank determination using the same procedure specified in 7.2 to 7.6, but omitting the test portion . In 7.5, using a one-mark pipette, addof the potassium sulfate solution (4.3) to the filtrate before adding the methyl red indicator solution (4.5). 8Exp
49、ression of results The sulfur content, of the sample, expressed as a percentage by mass, is given by the equation where is the mass, expressed in grams, of the test portion; is the mass, expressed in grams, of barium sulfate found in the determination; is the mass, expressed in grams, of barium sulfate found in the control; 20 ml 1 ml 200 ml 20 s 10 ml 30 min 100 mm 125 mm60 250 ml20 ml 800 C 15 min 0,1 mg 130 C 0,1 mg 25,0 ml wS wS= 13,74(m2 m3+0,033 48K2SO4) m1 m1 m2 m3 ISO 5931:2000(E) ISO 2000 A