1、BRITISH STANDARD BS 6043-1.9: 1989 ISO 9055:1988 Methods of sampling and test for Carbonaceous materials used in aluminium manufacture Part 1: Electrode pitch Section 1.9 Determination of sulphur content (bomb method) UDC 669.713.7:66.041 65:621.357.9:665.775:543.845:543.822BS6043-1.9:1989 This Brit
2、ish Standard, having been prepared under the directionof the Chemicals Standards Policy Committee, waspublished under the authorityof the Board of BSIandcomes into effect on 31 August 1989 BSI 10-1999 The following BSI references relate to the work on this standard: Committee reference CIC/24 Draft
3、for comment 87/53935 DC ISBN 0 580 17478 6 Committees responsible for this British Standard The preparation of this British Standard was entrusted by the Chemicals Standards Policy Committee (CIC/-) to Technical Committee CIC/24, upon which the following bodies were represented: Aluminium Federation
4、 British Ceramic Research Ltd. British Tar Industry Association Chemical Industries Association Institute of Petroleum Refractories Association of Great Britain Amendments issued since publication Amd. No. Date of issue CommentsBS6043-1.9:1989 BSI 10-1999 i Contents Page Committees responsible Insid
5、e front cover National foreword ii 1 Scope 1 2 Normative reference 1 3 Principle 1 4 Reagents 1 5 Apparatus 1 6 Sampling and test sample preparation 2 7 Procedure 2 8 Expression of results 3 9 Test report 4 Annex A (informative) Bibliography 5 Table 1 2 Table 2 2 Table 3 2 Table 4 4 Publication refe
6、rred to Inside back coverBS6043-1.9:1989 ii BSI 10-1999 National foreword This British Standard has been prepared under the direction of the Chemicals Standards Policy Committee to provide methods of sampling and test for carbonaceous materials used in the production of aluminium. The standard is pu
7、blished in two Parts, each Part being divided into Sections. The two Parts are: Part 1: Electrode pitch; Part 2: Electrode coke. Part 1 comprises the following Sections: The UK did not approve the determination of density (by pyknometer) method given in ISO6999:1983 and a national version using the
8、buoyancy method has been published. Other international methods of test for electrode pitch are under consideration and, subject to approval by the United Kingdom, will be published as they become available. This Section is identical with ISO9055 “Carbonaceous materials used in the production of alu
9、minium Pitch for electrodes Determination of sulfur content by the bomb method”, published by the International Organization for Standardization (ISO). Additional information. With reference to clause 4, water complying with grade3 of BS3978 “Specification for water for laboratory use” is suitable.
10、This standard describes a method of test only, and should not be used or quoted as a specification defining limits of purity. Reference to this Section should state that the method of test used is in accordance with BS6043-1.9:1989. A British Standard does not purport to include all the necessary pr
11、ovisions 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. Section Subject Identical with 1.1 Sampling ISO 6257 1.2 Water content (Dean and Stark method) ISO 5939 1.3
12、Softening point (ring and ball method) ISO 5940 1.4 Content of toluene-insoluble material ISO 6376 1.5 Content of quinoline-insoluble material ISO 6791 1.6 Coking value ISO 6998 1.7 Density 1.8 Ash ISO 8006 1.9 Sulphur content ISO 9055 Cross- reference International Standard Corresponding British St
13、andard ISO 6257:1980 BS 6043 Methods of sampling and test for carbonaceous materials used in aluminium manufacture Part 1 Electrode pitch Section 1.1:1981 Sampling (Identical) Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages1 to 6, an inside back c
14、over 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.BS6043-1.9:1989 BSI 10-1999 1 WARNING Strict adherence to all of the provisions prescribed in this Internationa
15、l Standard should ensure against explosive rupture of the bomb, or a blow-out, provided that the bomb is of proper design and construction and in good mechanical condition. It is desirable that the bomb beenclosed in a shield of steel plate at least13mm thick, or that equivalent protection be provid
16、ed against unforseeable contingencies. 1 Scope This International Standard specifies a method for determining the sulfur content of pitch used in the production of aluminium. The method is applicable to pitches of both coal tar and petroleum origin, provided that they contain at least 0,1% (m/m) sul
17、fur. 2 Normative reference The following standard contains provisions which, through reference in this text, constitute provisions of this International Standard. At the time of publication, the edition indicated was valid. All standards are subject to revision, and parties to agreements based on th
18、is International Standard are encouraged to investigate the possibility of applying the most recent edition of the standard indicated below. Members of IEC and ISO maintain registers of currently valid International Standards. ISO 6257:1980, Carbonaceous materials used in the production of aluminium
19、 Pitch for electrodes Sampling. 3 Principle Oxidation of the sample by combustion in a bomb containing oxygen under pressure. Gravimetric determination of the sulfur, in the form of sulfate in the bomb washings, as barium sulfate. 4 Reagents During the analysis, use only reagents of recognized analy
20、tical grade and only distilled water or water of equivalent purity. 4.1 Hydrochloric acid, approximately 1,19 g/ml, approximately 37% (m/m) solution. 4.2 Bromine water, saturated. 4.3 Barium chloride, 85 g/l solution. Dissolve 100g of barium chloride dihydrate (BaCl 2 .2H 2 O) in water and dilute to
21、 1 000ml. 4.4 Sodium carbonate, 50g/l solution. Dissolve 135g of sodium carbonate decahydrate (Na 2 CO 3 .10H 2 O) or its equivalent mass in water and dilute to 1000ml. 4.5 Oxygen, free of combustible material and sulfur compounds, available at a pressure of 4,053 MPa 1) . 4.6 White oil: liquid para
22、ffin B.P. or equivalent. 5 Apparatus Ordinary laboratory apparatus and 5.1 Bomb, of capacity of not less than 300ml, and so constructed that it will not leak during the test and that quantitative recovery of the liquids from the bomb may be readily achieved. The inner surface of the bomb may be made
23、 of stainless steel or any other material that will not be affected by the combustion process or products. Materials used in the bomb assembly, such as the head gasket and the lead-wire insulation, shall be resistant to heat and chemical action, and shall not undergo any reaction that will affect th
24、e sulfur content of the liquid in the bomb3. 5.2 Platinum sample cup, of outside diameter24mm at the bottom and 27mm at the top, height 12mm and mass 10g to 11g. 5.3 Platinum firing wire, 0,4mm diameter approximately. 5.4 Ignition circuit, capable of supplying sufficient current to ignite the cotton
25、 wicking or nylon thread without melting the wire. The current shall not be drawn directly from the mains and the voltage shall not exceed 25V. WARNING The switch in the ignition circuit shall be of a type which remains open, except when held in a closed position by the operator. 5.5 White cotton wi
26、cking, or white nylon sewing thread. 5.6 Emery polishing paper, No. 00 or equivalent. 5.7 Chromium(III) oxide paste, grit free. 5.8 Cold water bath 5.9 Porcelain filter crucible, P10 series (porosity44m to 104m). 1) 1 MPa = 1 MN/m 2BS6043-1.9:1989 2 BSI 10-1999 6 Sampling and test sample preparation
27、 6.1 Sampling Sample the pitch for electrodes in accordance with ISO6257. 6.2 Preparation of test sample Prepare the test sample immediately before the determination. If it is sufficiently hard, grind the whole of the test sample with a pestle and mortar to a particle size of less than2004m. If the
28、pitch is too soft for grinding, melt and mix the sample, ensuring that its temperature does not exceed 150 C and that the melting period does not exceed 10min. The material for the test portion may be taken from the molten sample. 7 Procedure 7.1 Preparation of bomb and test portion Cut a piece of f
29、iring wire (5.3) 100mm in length. Coil the middle section (about20mm) and attach the free ends to the terminals. Arrange the coil so that it will be above and to oneside of the sample cup (5.2). Insert between twoloops of the coil a wisp of the cotton or nylon thread (5.5) of such length that one en
30、d will extend into the sample cup. Place about 5ml of the sodium carbonate solution (4.4) in the bomb (5.1) and rotate the bomb in such a manner that the interior surface is moistened by the solution. Introduce into the sample cup the quantities ofsample and, if required, white oil (4.6) specifiedin
31、Table 1, weighing the sample to the nearest 0,1mg. (When white oil is used, stir the mixture with a short length of silica rod and allow the rod to remain in the sample cup during the combustion.) WARNING Do not use more than 0,8g total of sample and white oil or other low-sulfur combustible materia
32、l. Table 1 After repeated use of the bomb for sulfur determinations, a film may be noticed on the inner surface. This dullness shall be removed by periodic polishing of the bomb. A satisfactory method for doing this is to rotate the bomb in a lathe at about300 r/min and polish the inside surface wit
33、h emery polishing paper (5.6), coated with a light machine oil to prevent deep cutting, and then with the chromium(III) oxide paste (5.7) and water. This procedure will remove all but very deep pits and put a high polish on the surface. Before using the bomb, it shall be washed with soap and water t
34、o remove oil or paste left from the polishing operation. Use of sample masses containing over 20mg of chlorine may cause corrosion of the bomb. To avoid this, it is recommended that, for samples containing over 2% (m/m) chlorine, the sample mass be based on the chlorine content as given in the follo
35、wing table: Table 2 If the sample is not readily miscible with white oil, some other low-sulfur combustible diluent may be substituted. However, the combined mass of sample and non-volatile diluent shall not exceed 0,8g. 7.2 Addition of oxygen Place the sample cup in position and arrange the cotton
36、wisp or nylon thread so that the end dips into the sample. Assemble the bomb and tighten the cover securely. WARNING Do not add oxygen or ignite the sample if the bomb has been jarred, dropped or tilted. Admit oxygen slowly (to avoid blowing the oil from the cup) until the pressure indicated inTable
37、 3 is reached. Table 3 Sulfur content Mass of test portion Mass of white oil % (m/m) g g u 5 0,6 to 0,8 0 5 0,3 to 0,4 0,3 to 0,4 Chlorine content Mass of sample Mass of white oil % (m/m) g g 2 to 5 0,4 0,4 5 to 10 0,2 0,6 10 to 20 0,1 0,7 20 to 50 0,05 0,7 Capacity of bomb Minimum gauge pressure a
38、Maximum gauge pressure a ml MPa MPa 300 to 350 3,95 4,15 350 to 400 3,65 3,85 400 to 450 3,14 3,34 450 to 500 2,84 3,04 a The minimum pressures are specified to provide sufficient oxygen for complete combustion and the maximum pressures represent a safety requirement.BS6043-1.9:1989 BSI 10-1999 3 7.
39、3 Combustion Immerse the bomb in the cold water bath (5.8). Connect the terminals to the open electrical circuit(5.4). Close the circuit to ignite the sample. WARNING Do not go near the bomb till at least 20s after firing. Remove the bomb from the bath after a further immersion period of at least 10
40、min. Release the pressure at a slow, uniform rate such that the operation requires not less than 1min. Open the bomb and examine the contents. If traces of unburned pitch or sooty deposits are found, discard the determination and thoroughly clean the bomb before again putting it in use. 7.4 Collecti
41、on of sulfur solution Rinse the interior of the bomb, the oil cup, and the inner surface of the bomb cover with a fine jet of water, and collect the washings in a 600ml beaker having a mark to indicate 75ml. Remove any precipitate in the bomb by means of a rubber policeman. Wash the base of the term
42、inals until the washings are neutral to a suitable indicator. (The volume of the washings is normally in excess of 300ml.) Add 10ml of the saturated bromine water (4.2) to the washings in the beaker. Place the sample cup in a 50ml beaker. Add 5ml of the saturated bromine water, 2ml of the hydrochlor
43、ic acid (4.1) and enough water just to cover the cup. Heat the contents of the beaker to just below its boiling point for 3min to 4min and add to the beaker containing the bomb washings. Wash the sample cup and the 50ml beaker thoroughly with water. Remove any precipitate in the cup by means of a ru
44、bber policeman. Add the washings from the cup and the 50ml beaker, and the precipitate, if any, to the bomb washings in the 600ml beaker. Do not filter any of the washings, since filtering would remove any sulfur present as insoluble material. 7.5 Determination Evaporate the combined washings to 200
45、ml on a hotplate or other source of heat. Adjust the heat to maintain slow boiling of the solution and add 10ml of the barium chloride solution (4.3), either in a fine stream or drop by drop. Stir the solution during the addition and for 2min thereafter. Cover the beaker with a fluted watch glass an
46、d continue boiling slowly until the solution has evaporated to a volume of approximately 75ml as indicated by the mark on the beaker. Remove the beaker from the hotplate (or other source of heat) and allow it to cool for 1h before filtering. Filter the supernatant liquid through an ashless, quantita
47、tive filter paper (see note1). Wash the precipitate with water, first by decantation and then on the filter, until free from chloride. Transfer the paper and precipitate to a tared crucible weighed to the nearest 0,1mg and dry (see note2) at low heat until the moisture has evaporated. Char the paper
48、 completely without igniting it, and finally heat at a bright red heat until the residue is white in colour. After combustion is complete, allow the crucible to cool to room temperature, and weigh to the nearest 0,1mg. NOTE 1The tared porcelain filter crucible (5.9) may be used in place of the filte
49、r paper. In this case the precipitate is washed free of chloride and then dried to constant mass at 500 C 25 C. NOTE 2A satisfactory means of drying, charring and combusting the paper and precipitate is to place the crucible containing the wet filter paper in a cold electric muffle furnace and to turn on the current. Drying, charring, and combustion usually will occur at the desired rate. 7.6 Blank Make a blank determination whenever new reagents, white oil or other low-sulfur combustible material are used. When running a blank on white oil,
