[bs 1016-104.3-1998] -- methods for analysis and testing of coal and coke..pdf

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BRITISH STANDARD BS 1016-104.3:1998ISO 562:1998

Methods for analysisand testing of coal and

coke

Part 104: Proximate analysis

Section 104.3: Determination of volatilematter content

ICS 73,040; 75.160.10


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This British Standard, havingbeen prepared under thedirection of the Sector Boardfor Materials and Chemicals,was published under theauthority of the StandardsBoard and comesinto effect on15 April 1998

BSI 04-1999

ISBN 0 580 29677 6

National foreword

This British Standard is the UK implementation of ISO 562:1998. Itsupersedes BS 1016-104.3:1991 which is withdrawn.

The UK participation in its preparation was entrusted to Technical CommitteeSFI/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 anyenquiries on the interpretation, or proposals for change, and keep the UKinterests informed;

monitor related international and European developments andpromulgate them in the UK.

A list of organizations represented on this committee can be obtained onrequest to its secretary.

Cross-references

The British Standards which implement international or Europeanpublications referred to in this document may be found in the BSI StandardsCatalogue under the section entitled International Standards CorrespondenceIndex, or by using the Find facility of the BSI Standards ElectronicCatalogue.

A British Standard does not purport to include all the necessary provisions ofa contract. Users of British Standards are responsible for their correctapplication.

Compliance with a British Standard does not of itself confer immunityfrom legal obligations.

Summary of pages

This document comprises a front cover, an inside front cover, pages i and ii,the ISO title page, page ii, pages 1 to 6 and a back cover.

This standard has been updated (see copyright date) and may have hadamendments incorporated. This will be indicated in the amendment table onthe inside front cover.

Amendments issued since publication

Amd. No. Date Comments


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Contents

Page

National foreword Inside front cover

Foreword iiiIntroduction 1

1 Scope 1

2 Normative references 1

3 Principle 1

4 Reagent 1

5 Apparatus 1

6 Preparation of the test sample 4

7 Procedure 4

8 Expression of results 5

9 Precision 5

10 Test report 5Annex A (informative) Bibliography 6

Figure 1 Example of suitable furnace 2

Figure 2 Silica crucible and lid 3

Figure 3 Crucible stands 4

Table 1 5


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ii blank


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Foreword

ISO (the International Organization for Standardization) is a worldwidefederation of national standards bodies (ISO member bodies). The work ofpreparing International Standards is normally carried out through ISO technicalcommittees. Each member body interested in a subject for which a technicalcommittee has been established has the right to be represented on that committee.

International organizations, governmental and non-governmental, in liaison withISO, also take part in the work. ISO collaborates closely with the InternationalElectrotechnical Commission (IEC) on all matters of electrotechnicalstandardization.

Draft International Standards adopted by the technical committees are circulatedto the member bodies for voting. Publication as an International Standard requiresapproval by at least 75 % of the member bodies casting a vote.

International Standard ISO 562 was prepared by Technical CommitteeISO/TC 27, Solid mineral fuels, Subcommittee SC 5, Methods of analysis.

This second edition cancels and replaces the first edition (ISO 562:1981), whichhas been technically revised.

Annex A of this International Standard is for information only.

Descriptors:Solid fuels, fossil fuels, coal, pit-coal, coke, tests, determination of content, volatilematter, gravimetric analysis, test equipment.


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Introduction

The volatile matter is determined as the loss in

mass, less that due to moisture, when coal or coke isheated out of contact with air under standardizedconditions. The test is empirical and, in order toensure reproducible results, it is essential that therate of heating, the final temperature and theoverall duration of the test are carefully controlled.It is also essential to exclude air from the coal orcoke during heating to prevent oxidation. The fit ofthe crucible lid is therefore critical. The moisturecontent of the sample is determined at the sametime as the volatile matter so that the appropriatecorrection can be made.

Mineral matter associated with the sample may alsolose mass under the conditions of the test, themagnitude of the loss being dependent on both thenature and the quantity of the minerals present.

NOTE When applying this International Standard forclassification purposes, to samples obtained directly from coalseams, special care has to be given to the ash content.

The apparatus and procedure are specified so thatone or more determinations may be performedsimultaneously in the furnace.

1 Scope

This International Standard specifies a method of

determining the volatile matter of hard coal and ofcoke. It is not applicable to brown coals and lignites.

2 Normative references

The following standards contain provisions which,through reference in this text, constitute provisionsof this International Standard. At the time ofpublication, the editions indicated were valid. Allstandards are subject to revision, and parties toagreements based on this International Standardare encouraged to investigate the possibility ofapplying the most recent editions of the standards

indicated below. Members of IEC and ISO maintainregisters of currently valid International Standards.

ISO 331:1983, Coal Determination of moisture inthe analysis sample Direct gravimetric method.

ISO 687:1974, Coke Determination of moisture inthe analysis sample.

ISO 11722:1), Solid mineral fuels Hard coal Determination of moisture in the analysis sample bydrying in nitrogen.

3 Principle

A portion of the sample is heated out of contact with

air at 900 C for 7 min. The percentage of volatilematter is calculated from the loss in mass of the testportion after deducting the loss in mass due tomoisture.

4 Reagent

Cyclohexane of recognized analytical grade.

5 Apparatus

5.1 Furnace,heated by electricity, in which a zone ofuniform temperature of 900 C 5 C can bemaintained. It may be of the stop-ended type or

fitted at the back with a flue approximately 25 mmdiameter and 150 mm long (see Figure 1).

NOTE It is important for furnaces with flues that the furnacedoor seal well. The flue should not reach far out of the oven andshould be fitted with a butterfly valve to restrict airflow throughthe furnace.

Its heat capacity shall be such that, with an initialtemperature of 900 C, the temperature is regainedwithin 4 min after insertion of a cold stand and itscrucibles. The temperature is measured with athermocouple, as described in 5.2.Normally the furnace will be designed specificallyeither for multiple determinations using a number

of crucibles in one stand or for receiving one crucibleand its stand. In the first case, the zone of uniformtemperature shall be at least 160 mm 100 mm; inthe latter case, a zone of diameter 40 mm will besufficient.

A position for the crucible stand shall be chosenwithin the zone of uniform temperature and thisposition shall be used for all determinations. Thetemperature of 900 C shall be attained as closely aspossible with a specified tolerance of 5 C in orderto compensate for inherent errors in thetemperature measurement and lack of uniformity inthe temperature distribution.

5.2 Thermocouple,unsheathed, of wire no thickerthan 1 mm. It should be long enough to reach thecentre of the underside of each crucible when placedin the zone of uniform temperature on beinginserted through the front or rear of the furnace.The thermojunction shall be placed midwaybetween the base of the crucible in its stand and thefloor of the furnace. If the stand holds more than onecrucible, the temperature under each crucible shallbe checked in the same manner.

1) To be published.


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If desired, a sheathed thermocouple may bepermanently installed in the furnace (see Figure 1)

with its thermojunction as close as possible to thecentre of the zone of uniform temperature; in thiscase furnace temperature readings shall becorrelated at frequent intervals with those of theunsheathed thermocouple, which is thus insertedonly when necessary.

NOTE The temperature/electromotive force relationship of athermojunction maintained at elevated temperatures graduallychanges with time.

5.3 Crucible,cylindrical, with a well-fitting lid, bothof fused silica. The crucible with lid shall have amass between 10 g and 14 g and dimensionsapproximating to those shown in Figure 2. The fit of

the lid on the crucible is critical to the determinationand a lid shall be selected to match the crucible sothat the horizontal clearance between them is nogreater than 0,5 mm. After selection, the crucibleand the lid shall be ground together to give smoothsurfaces and then be given a common distinguishingmark.

NOTE When performing multiple determinations on highlyswelling coals, it may be necessary to use taller crucibles; thesemay be up to 45 mm in height without affecting the determined

volatile matter, provided that the specified rate of temperaturerecovery be maintained.

5.4 Crucible stand,on which the crucible is placed inthe furnace, such that the appropriate rate ofheating can be achieved. For example, it may consistof the following:

a) for single determinations, a ring ofheat-resistant steel wire as shown in Figure 3 a)with ceramic discs, 25 mm diameter and 2 mmthick, resting on the inner projection of its legs or

b) for multiple determinations, a tray ofheat-resistant steel wire as shown in Figure 3 b),of appropriate size, with ceramic plates 2 mmthick supporting the crucibles.

5.5Balance,capable of reading to thenearest 0,1 mg.

Figure 1 Example of suitable furnace


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Figure 2 Silica crucible and lid


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6 Preparation of the test sample

The coal or coke used for the determination ofvolatile matter is the general analysis test sample(ground to pass a sieve of 212 m aperture).

The sample shall be well mixed and in moistureequilibrium with the laboratory atmosphere.

A test portion from the same test sample is

separated for determination of moisture parallel tothe determination of volatile matter.

7 Procedure

7.1 Furnace temperature checking

Adjust the temperature of the zone in thefurnace (5.1), containing either a stand with onecrucible and lid [Figure 3 a)] or a stand with therequisite number of crucibles and lids [Figure 3 b)],to 900 C 5 C as indicated by the correctly located

thermocouple (5.2). Check that the temperatureunder each crucible, at the same height, lies withinthe temperature tolerance of the uniform zone.

Figure 3 Crucible stands


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NOTE Temperature checking should be made before startingdeterminations. However, when several analyses are performedper day, a daily temperature check is sufficient. The check of the

temperature recovery criterion (5.1) should be dealt with in asimilar way.

7.2 Volatile matter determination

Fill either a stand with one empty crucible and lid[Figure 3 a)] or a stand with the requisite number ofempty crucibles and lids [Figure 3 b)] and insert inthe oven. Maintain at 900 C 5 C for 7 min.Remove the crucible(s) from the furnace and allowto cool to room temperature on a thick metal plate.

As soon as they are cool, weigh each empty crucibleand lid and weigh into each crucible, to thenearest 0,1 mg, 1 0,1 g of test sample. Replace the

lid and tap each crucible on a clean hard surfaceuntil the test portion forms a layer of even thicknesson the bottom of the crucible. If the sample is ofcoke, remove the lid of the charged crucible, add 2to 4 drops of cyclohexane (4) and replace the lid.

NOTE The addition of cyclohexane prevents oxidation of thecoke but does not prevent adsorption of gases, e.g. nitrogen.

Place the charged crucible(s) in a cold stand,transfer to the furnace, close the door and leavefor 7 min 5 s. Remove and allow to cool to roomtemperature. When cool, weigh the crucible(s) tothe nearest 0,1 mg in the same manner as for theempty crucible(s).

NOTE 1 The same treatment of the crucible before and after thedetermination minimizes the effect of any film of water adsorbedon its surface, while the rapid cooling reduces absorption ofmoisture by the coal or coke residue.

NOTE 2 If multiple determinations are being made, any vacantplaces in the stand should be filled with empty crucibles.

8 Expression of results

The volatile matter Vin the sample as analysed,expressed as a percentage by mass, is given by theequation:

where

Report the result, as the mean of duplicatedeterminations, to the nearest 0,1 % (m/m). The

results of the determination described in thisInternational Standard are reported on theair-dried basis. Calculation of the results to otherbases is dealt with in ISO 1170.

9 Precision

Table 1

9.1 Repeatability limit

The results of the duplicate determinations

(performed within a short period of time, but notsimultaneously) in the same laboratory by the sameoperator using the same apparatus on tworepresentative test portions taken from the samegeneral analysis test sample, shall not differ bymore than the values given in Table 1.

9.2 Reproducibility critical difference

The means of the results of duplicatedeterminations, performed in each of two differentlaboratories on representative test portions takenfrom the same general analysis test sample shall notdiffer by more than the above values.

10 Test report

The test report shall include the followinginformation:

a) the identification of the sample tested;

b) the method used;

c) the date of the determination;

d) results of the determination performed,together with the relevant analysis basis(e.g. air dry);

e) any unusual features noted during thedetermination;

f) a reference to this International Standard;

g) any operation not included in thisInternational Standard or regarded as optional.

m1 is the mass, in grams, of the emptycrucible and lid;

m2 is the mass, in grams, of the crucible andlid and test portion before heating;

m3 is the mass, in grams, of the crucible andlid and contents after heating;

M is the moisture, as a percentage by mass,in the sample as analysed, determinedaccording to the method specified inISO 331 (to be superseded by ISO 11722)or ISO 687.

V100 m2 m3( )

m2 m1( )-------------------------------------- M=

Volatile matter

Maximum acceptable differencesbetween, results obtained

(calculated to the same moisture content)

Repeatabilitylimit

Reproducibilitycritical difference

Hard coal ofvolatilematter < 10 %

0,3 % absolute 0,5 % absolute

Hard coal ofvolatilematter >10 %

3 % of themean result

0,5 % absoluteor 4 % of themean result,whichever isgreater

Coke 0,2 % absolute 0,3 % absolute


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Annex A (informative)Bibliography

[1] ISO 1170:1977, Coal and coke Calculation of analyses to different bases.

[2] ISO 1213-2:1992, Solid mineral fuels Vocabulary Part 2: Terms relating to sampling testing andanalysis.


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