ISO 5074:1980

ational Standard 74
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IALISATION
INTERNATIONAL ORGAN1 ATION FOR STANDARDIZATION*ME~YHAPOAHAR OPrAHM3Ai4HR il0 CTAH~APTH3AUHHOûRGANlSATlON INTERNATIONALE DE N(
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e- Hard coa - Determination of Hardgrove grindability
index
Houille - Détermin tion de l'indice de broyabilité Hardgrove
First edition - 1980-10-15
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UDC 662.66 : 640.1 : 539.562
Ref. No. ISO507r O (E)
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Descriptors : coal, te ts, grindability, test specimen conditioning, calibrating, grain size analysis, test equipment.
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Foreword
IS0 (the International Organization for Standardization) is a worldwide federation of
national standards institutes (IS0 member bodies). The work of developing Inter-
national Standards is carried out through IS0 technical committees. Every member
body interested in a subject for which a technical committee has been set up has the
right to be represented on that committee. International organizations, governmental
and non-governmental, in liaison with ISO, also take part in the work.
Draft International Standards adopted by the technical committees are circulated to
the member bodies for approval before their acceptance as International Standards by
the IS0 Council.
International Standard IS0 5074 was developed by Technical Committee ISO/TC 27,
Solid mineral fuels, and was circulated to the member bodies in November 1978.
It has been approved by the member bodies of the following countries :
Australia Denmark Romania
Austria France South Africa, Rep. of
Belgium Germany, F. R. Spain
Bulgaria India United Kingdom
Canada Japan USA
China Korea, Rep. of USSR
Czechoslovakia Netherlands Yugoslavia
No member body expressed disapproval of the document.
O International Organization for Standardization, 1980 O
Printed in Switzerland

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AL STANDARD IS0 5071
1980 (E)
- Determination of Hardgrove grindability
index
1 Scope and ield of application 5.4 Crusher : a laboratory crusher capable (
reducing
4.75 mm coal particles to 1,2 mm with the prod tion of a
method for determin-
minimum of material finer than 600 pm. In the cas of a plate
hard coal') using the Hardgrove
mill, the plates shall be serrated and about 100 mm diameter,
for calibrating the test
the distance between the plates being adjustat and the
machine and for pre aring the standard reference coal samples.
relative frequency of rotation of the plates no1 Ixceeding
200 min -1. Roll mills or hammer mills shall not be ed .
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2 References
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5.5 Sieves :
5.5.1 Wire cloth test sieves, complying
requirements of IS0 3310/1, Series R 40/3, of ap
1,18 mm, 600 pm and 75 pm respectively, and ha\
and receiver of diameter about 200 mrn.
3 Definition
5.5.2 Protective sieve, with round or square ape
range 16 to 19 mrn, capable of nesting in the te$
definition applies. plate sieve with round holes is recommended; if a st
cloth sieve is used, it may become distorted throu
protective sieve and should, therefore, be marked a
for test sieving.
5.6 Mechanical sieving machine, capable of a
assembly of vertically nested sieves and a cover an<
diameter about 200 mm. The machine shall be able
ed sample of coal of limited size range
the motions of hand sieving. This may be achieve
ns in a laboratory apparatus of standard-
under defined c
ting a horizontal oscillatory motion of amplitude 2E
Hardgrove machine). Derivation of the
at a frequency of approximately 300 min-', whilst
top of the oscillating assembly with a mass of 1,9
through a vertical distance of about 25 mm under tl
reference material.
of gravity, at a frequency of approximately 150
minute.
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5 Apparatus
Alternatively, the nest of sieves, cover and recei
vibrated by an electromagnetic device, provided
5.1 Balance, capall le of weighing up to 100 g to an accuracy
performance is equivalent to the mechanically vibrat
of 0,Ol g.
described.
5.2 Balance, capible of weighing up to 1 500 g to an
5.7 Hardgrove grindability machine, as
accuracy of 1 g.
and with the essential tolerances shown in fi
a stationary grinding bowl, of hardened iro
Sample divide , as specified in A.6.3 of IS0 1988.
5.3 horizontal track in which run eight steel balls
11 The term "hard coal ' is used here as an indication of maturity or rank in the coalification sequence and is not related to the physical pr
the coal.

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I 4-1980 (E)
25,4 mm. The balls shall be driven by an upper grinding ring 8.2 Weigh a test portion of 50 I 0.01 g of the de-dusted
material, distribute it evenly in the grinding bowl and smooth
rotated at 19 to 21 min- 1. The upper grinding ring, which shall
the surface. Assemble the top grinding ring to the bowl and
be of similar material to the bowl, shall be connected to a spin-
fasten the bowl in position to the driving spindle, making sure
dle and shall be driven by an electric motor through reduction
that the load is evenly applied. Preset the counter and adjust
gears. A load shall be added to the spindle so that the total ver-
the automatic stopping device so that the machine will operate
tical force on the balls due to the top ring, gear, load and spin-
for 60 k 0,25 revolutions. Start the apparatus.
dle is 284 & 2 N, i.e. closely equivalent to a total mass of 29 tr
0,2 kg. The machine shall be fitted with a revolution counter
and an automatic device for stopping the machine after 60 k
8.3 When the rotation has stopped, switch off the machine
0,25 revolutions. It shall be calibrated by the method described
and dismantle the bowl assembly. Brush any adherent coal
in clause 8, before use for the determination of Hardgrove
dust onto the protective sieve (see 5.5.2) nested on the 75 pm
indices.
sieve and receiver. Empty the grinding balls and ground coal
onto the protective sieve. Brush any coal from the bowl and the
NOTE - The grinding bowl, balls and top grinding ring should be pro-
balls into the protective sieve and set them aside. Brush any
tected from rusting when not in use.
coal and dust from the inside and underside of the protective
sieve into the 75 pm sieve and set it aside.
6 Sampling
8.4 Replace the cover on the 75 pm sieve and shake the
assembled receiver, 75 pm sieve and cover for 10 min in the
'The gross sample shall be collected and prepared in accordance
sieving machine. Invert the sieve over a collector and carefully
with the requirements of IS0 1988, except that the initial
brush along the warp and weft of the cloth so that all the coal
crushing shall be to 4,75 mm instead of to 10 mm. The gross
on the sieve enters the collector. Return the cleaned sieve to
sample shall be reduced to a final sample of about 1 kg by using
the nest, add the coal from the collector and sieve for a further
a sample divider of suitable size and capacity (see 5.3).
5 min. Repeat this operation. Finally clean the sieve by
brushing so that the coal retained on the sieve and in the aper-
tures enters the collector, while all the coal that has passed
7 Preparation of test sample
through the apertures enters the undersize receiver.
Air-dry the final sample (see IS0 1988) and determine the
7.1
mass of the dried sample to the nearest gram.
8.5 Weigh separately, to the nearest 0,Ol g, the coal brushed
off the 75 pm sieve and the coal passing the 75 pm sieve. If the
Sieve the dried sample on a nest of sieves consisting of a
sum of th
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