1、BRITISH STANDARD BS 1016-106.6.1: 1997 ISO 587:1997 Methods for analysis and testing of coal and coke Part 106: Ultimate analysis of coal and coke Section 106.6 Determination of chlorine content Subsection 106.6.1 Eschka method ICS 75.160.10BS1016-106.6.1:1997 This British Standard, having been prep
2、ared under the directionof the Sector Board forMaterials and Chemicals, waspublished under the authorityof the Standards Boardand comes into effect on 15September1997 BSI09-1999 ISBN 0 580 28417 4 National foreword This British Standard is the UK implementation of ISO587:1997. Together with BS1016-1
3、06.6.2 it will supersede BS1016-8:1977. The UK participation in its preparation was entrusted to Technical Committee SFI/3, Analysis and testing of coal and coke, which has the responsibility to: aid enquirers to understand the text; present to the responsible international/European committee any en
4、quiries on the interpretation, or proposals for change, and keep the UK interests informed; monitor related international and European developments and promulgate them in the UK. Under a scheme for the rationalizing and restructuring of BS1016, the parts numbered from 1 to 21 are being gradually wit
5、hdrawn and replaced with parts in a new series. The full list of parts in the new series, together with the corresponding numbering of the old series and related ISO standards is given in BS 1016-100 General introduction and sampling report. A list of organizations represented on this committee can
6、be obtained on request to its secretary. Cross-references The British Standards which implement international or European publications referred to in this document may be found in the BSI Standards Catalogue under the section entitled “International Standards Correspondence Index”, or by using the “
7、Find” facility of the BSI Standards Electronic Catalogue. 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 le
8、gal obligations. Summary of pages This document comprises a front cover, an inside front cover, pagesi andii, theISO title page, pages ii to iv, pages1 to5 and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the am
9、endment table on the inside front cover. Amendments issued since publication Amd. No. Date CommentsBS1016-106.6.1:1997 BSI 09-1999 i Contents Page National foreword Inside front cover Foreword iii Text of ISO 587 1ii blankBS1016-106.6.1:1997 ii BSI 09-1999 Contents Page Foreword iii 1 Scope 1 2 Norm
10、ative references 1 3 Principle 1 4 Reagents 1 5 Apparatus 1 6 Preparation of the test sample 2 7 Procedure 2 8 Expression of results 3 9 Precision 4 10 Test report 4 Annex A (informative) Derivation of factors used in calculations inthisInternational Standard 5 Descriptors: Fossil fuels, solid fuels
11、, coal, lignite, coke, chemical analysis, determination of content, chlorine, extraction methods.BS1016-106.6.1:1997 BSI 09-1999 iii Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing Int
12、ernational Standards is normally carried out through ISO technical committees. 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 liaison w
13、ith ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as
14、an International Standard requires approval by at least75% of the member bodies casting a vote. International Standard ISO587 was prepared by Technical Committee ISO/TC27, Solid mineral fuels, Subcommittee SC5, Methods of analysis. This third edition cancels and replaces the second edition (ISO 587:
15、1981), which has been technically revised. Annex A of this International Standard is for information only.iv blankBS1016-106.6.1:1997 BSI 09-1999 1 1 Scope This International Standard specifies a method of determining the chlorine content of hard coal, brown coals and lignite, and coke using Eschka
16、mixture. 2 Normative references The following standards contain provisions which, through reference in this text, constitute provisions of this International Standard. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements base
17、d on this International Standard are encouraged to investigate the possibility of applying the most recent editions of the standards indicated below. Members of IEC and ISO maintain registers of currently valid International Standards. ISO 331:1983, Coal Determination of moisture in the analysis sam
18、ple Direct gravimetric method. ISO 687:1974, Coke Determination of moisture in the analysis sample. ISO 1015:1992, Brown coals and lignites Determination of moisture content Direct volumetric method. ISO 1170:1977, Coal and coke Calculation of analyses to different bases. ISO 1988:1975, Hard coal Sa
19、mpling. ISO 2309:1980, Coke Sampling. ISO 5068:1983, Brown coals and lignites Determination of moisture content Indirect gravimetric method. 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
20、 9411-1:1994, Solid mineral fuels Mechanical sampling from moving streams Part 1: Coal. ISO 9411-2:1993, Solid mineral fuels Mechanical sampling from moving streams Part 2: Coke. 3 Principle A known mass of sample is ignited in intimate contact with Eschka mixture in an oxidizing atmosphere to remov
21、e combustible matter and to convert the chlorine to alkaline chlorides. These are extracted with nitric acid or water and determined by either the Volhard or the Mohr method, or by potentiometric titration using an Ion Selective Electrode (ISE). 4 Reagents WARNING Care should be exercised when handl
22、ing reagents, many of which are toxic and corrosive. During analysis, unless otherwise stated, use only reagents of recognized analytical grade and only distilled water, or water of equivalent purity. 4.1 For all methods 4.1.1 Eschka mixture Mix two parts by mass of light, calcined magnesium oxide w
23、ith one part of anhydrous sodium or potassium carbonate. The mixture shall entirely pass a test sieve of 0,212mm nominal aperture. 4.1.2 Nitric acid, concentrated, chlorine-free, approximately 70 % (m/m). 4.2 For the Volhard and ISE methods 4.2.1 Silver nitrate, standard volumetric solution, c(AgNO
24、3 ) = 0,025 mol/l. Heat crushed, crystalline silver nitrate at 125 C for two to three hours. Dissolve 4,247 g in water and dilute to 1l. Store in an amber glass bottle. 4.3 For the Volhard method only 4.3.1 3, 5, 5-trimethylhexan-1-ol. 4.3.2 n-Hexan-1-ol. 4.3.3 Potassium thiocyanate, standard volume
25、tric solution, c(KSCN) . 0,025 mol/l. Dissolve 2,4g of potassium thiocyanate in water and dilute to 1l. Titrate against the silver nitrate solution (4.2.1) and calculate the exact equivalence. 4.3.4 Iron(III) alum (ammonium iron(III) sulfate) indicator, saturated solution. Saturate100ml of water wit
26、h approximately125g or iron(III) alum (NH 4 ) 2 SO 4 Fe 2 (SO 4 ) 3 24H 2 O and add sufficient nitric acid (4.1.2) to remove the brown colour. 4.4 For the Mohr method only 4.4.1 Silver nitrate, standard volumetric solution, c(AgNO 3 ) = 0,050 mol/l. Weigh 8,494g of silver nitrate, dried as in (4.2.1
27、), dissolve in water and dilute to 1l. Store in an amber glass bottle. 4.4.2 Potassium chromate, indicator solution. Dissolve5g of potassium chromate in100ml of water. 5 Apparatus 5.1 Analytical balance, capable of weighing to the nearest0,1mg.BS1016-106.6.1:1997 2 BSI 09-1999 5.2 Graduated glasswar
28、e, conforming to the requirements for Grade A in the International Standards prepared by ISO/TC 48,Laboratory glassware and related apparatus. 5.3 Electrically heated muffle furnace, capable of being maintained at a temperature of 675 C 25 C, with adequate ventilation. 5.4 Crucible, of platinum, sil
29、ica or glazed porcelain, of approximately 25ml capacity. 5.5 Flat plate, 6mm thick, of silica or other suitable refractory material, which fits easily into the muffle furnace (5.3). 5.6 Potentiometric titration assembly, equipped with a chloride ion selective electrode and double junction reference
30、electrode. 6 Preparation of the test sample The test sample is the general analysis test sample prepared in accordance with ISO 1988, ISO 2309, ISO 5069-2, ISO 9411-1 or ISO 9411-2 as appropriate. Ensure that the moisture content of the sample is in equilibrium with the laboratory atmosphere, exposi
31、ng it, if necessary, in a thin layer for the minimum time required to achieve equilibrium. Before commencing the determination, thoroughly mix the equilibrated test sample for at least one minute, preferably by mechanical means. If the results are to be calculated other than on an “air-dried” basis
32、(see clause8), then, after weighing the test portion (see7.1), determine the moisture content using a further portion of the test sample by the method described in ISO331, ISO687, ISO1015 or ISO5068, as appropriate. 7 Procedure 7.1 Combustion Weigh, to the nearest 0,1mg, a test portion of approximat
33、ely 1g, for samples with an expected chlorine content greater than 0,1% (m/m), or2g for samples with a lower expected chlorine content. Cover the bottom of the crucible (5.4) uniformly with0,5g of the Eschka mixture (4.1.1). Thoroughly mix the test portion with2,5g of the Eschka mixture in a suitabl
34、e container. Transfer the mixture to the crucible, level the contents by gently tapping the crucible on the bench and cover uniformly with a further1g of the Eschka mixture. NOTE 1It is convenient to weigh out initially4g of the Eschka mixture and to extract the portions required for the bottom and
35、top layers using a small glass tube, calibrated for each batch of Eschka mixture, to deliver0,5g and1g portions without weighing. The bottom layer of Eschka mixture reduces attack on silica and porcelain surfaces so that extraction of chlorine with hot water is complete even when the surface deterio
36、rates. For coals, place the charged crucible in the cold muffle furnace (5.3) and raise the temperature to675 C 25 C in about one hour. Maintain this temperature for a further two hours. Withdraw the crucible and allow to cool. For coke, place the charged crucible on the cold flat plate (5.5) and in
37、sert into the muffle furnace at a temperature of 675 C 25 C. Maintain this temperature for two hours. Withdraw the crucible and allow to cool. NOTE 2Cracking of the porcelain crucibles is prevented if they are cooled slowly by insertion into supports constructed from a light, porous refractory mater
38、ial after removal from the muffle furnace. 7.2 Completion Complete the determination by either the Volhard(7.2.1), the Mohr (7.2.2) or the ISE method(7.2.3). 7.2.1 Volhard method Transfer the incinerated mixture to a beaker, wash the crucible with about 125ml of hot water and add the washings to the
39、 beaker. If unburnt particles are present, stop the test and repeat the determination, extending the combustion time. Cautiously add20ml of the nitric acid (4.1.2) and cover the beaker with a clock glass, swirling or stirring the contents, if necessary, to help dissolution. If necessary, filter the
40、solution through a rapid-filtering, hardened, acid-washed filter paper, collecting the filtrate in a conical flask. 1)Wash the paper with a small quantity of hot water (for example four lots of5ml to10ml), cool to room temperature and add20ml of the silver nitrate solution (4.2.1) to the flask and m
41、ix thoroughly. Immediately add5ml of the3, 5, 5-trimethylhexan-1-ol (4.3.1) or n-hexan-1-ol (4.3.2), shake the solution for one minute to coagulate the precipitate, add eight to ten drops of the iron(III) alum indicator solution (4.3.4) and titrate with the potassium thiocyanate solution(4.3.3). The
42、 end-point is reached when the solution becomes faintly orange-pink in colour. 1) Filtration is usually unnecessary when using 1g test portions of low-ash fuels, but is required when dealing with larger test portions or with high-ash fuels.BS1016-106.6.1:1997 BSI 09-1999 3 7.2.2 Mohr method Transfer
43、 the incinerated mixture to a beaker, wash the crucible with hot water, collect the washings in the beaker and crush the residue in the beaker with a flat-ended glass rod. If unburnt particles are present, stop the determination and repeat the test extending the combustion time. Heat the solution to
44、 boiling point and filter, using a filter paper pad or rapid filtering paper, collecting the filtrate in a conical flask. Wash the residue with five portions (5ml each) of hot water, collecting the washings in the flask. Neutralize the solution with the nitric acid (4.1.2), using a pH paper. Add ten
45、 drops of the potassium chromate indicator (4.4.2) and titrate with the silver nitrate solution (4.4.1). The end-point is indicated by the first appearance of a brown coloration. 7.2.3 ISE method Transfer the incinerated mixture to a beaker, wash the crucible with50ml to70ml of hot water and add the
46、 washings to the beaker. If unburnt particles are present, stop the determination and repeat the test extending the combustion time. Cautiously add20ml of the nitric acid (4.1.2) and cover the beaker with a clock glass, swirling or stirring the contents, if necessary, to help dissolution. If necessa
47、ry, filter the solution through a rapid-filtering, hardened, acid-washed filter paper, collecting the filtrate in a conical flask. 2)Wash the paper with a small quantity of hot water (the total volume of the filtrate should not exceed 100ml) and cool to room temperature. Titrate with 0,025M silver n
48、itrate solution (4.2.1), using the potentiometric titration assembly (5.6). 7.3 Blank test Carry out a blank test, using the same procedure as described in7.1 and 7.2 but omitting the test portion. This assesses both the chlorine in the reagents and any contamination in the laboratory atmosphere. Th
49、is shall not be quantitatively significant. 8 Expression of results 8.1 Volhard method The chlorine content (W Cl ) of the sample, as analyzed, expressed as a percentage by mass, is given by the formula where 8.2 Mohr titration The chlorine content (W Cl ) of the sample, as analyzed, expressed as a percentage by mass, is given by the formula where 8.3 ISE method The chlorine content (W Cl ) of the sample, as analyzed, expressed as a percentage by mass, is given by the formula where 2) Filtration is usually unnecessa
