SIST ISO 10752:1998

SLOVENSKI STANDARD
SIST ISO 10752:1998
01-november-1998
1DSUDYH]DVRUWLUDQMHSUHPRJD9UHGQRWHQMHXþLQND
Coal sizing equipment -- Performance evaluation
Charbon -- Équipement pour la granulométrie -- Évaluation de l'aptitude à l'emploi
Ta slovenski standard je istoveten z: ISO 10752:1994
ICS:
73.120 Oprema za predelavo rudnin Equipment for processing of
minerals
SIST ISO 10752:1998 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST ISO 10752:1998

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SIST ISO 10752:1998
INTERNATIONAL
ISO
STANDARD 10752
First edition
1994-05-15
Coal sizing equipment - Performance
evaluation
- Equipement pour Ia granulom&rie - Evaluation de I ’aptitude
Charbon
a I ’emploi
Reference number
ISO 10752: 1994(E)

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SIST ISO 10752:1998
ISO 10752:1994(E)
Contents
Page
1
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1 Scope
1
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*.
2 Normative references
1
3 Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .*.
2
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4 Performance criteria
2
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5 Performance Parameters
. . . . . . . . . . 2
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6 Performance test procedures
3
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7 Analytical procedures
. . . . 3
8 Evaluation and presentation of Performance characteristics
6
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9 Tabular and graphical presentation
Annexes
A Calculation of the yield of each product of a size Separation from size
. . . . . . . . . . . . . . . . . . . . . . . .*. 13
analyses of feed and product materials
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
B Worked example - Vibrating Screen
................................................. 22
C Worked example - Cyclone
............................................... 29
D Worked example - Deduster
0 ISO 1994
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced
or utilized In any form or by any means, electronie or mechanical, inciuding photocopying and
microfilm, withoui Permission in writing from the publisher.
International Organization for Standardization
Gase Postale 56 l CH-1 211 Geneve 20 l Switzerland
Printed in Switzerland
ii

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SIST ISO 10752:1998
ISO 10752:1994(E)
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 carried out through ISO
technical committees. Esch 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 with 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 an International
Standard requires approval by at least 75 % of the member bodies casting
a vote.
International Standard ISO 10752 was prepared by Technical Committee
lSO/TC 27, Solid mineral fuels, Subcommittee SC 1, Coal preparation.
Terminology and performante.
Annex A forms an integral patt of this International Standard. Annexes B,
C and D are for information only.
. . .
Ill

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SIST ISO 10752:1998
ISO 10752:1994(E)
0 ISO
Introduction
A Standard expression of Performance is required to define the accuracy
of Separation of a particular item, to assist in the comparison of the per-
formante of different items of coal sizing equipment and in the prediction
of Separation results.
iv

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SIST ISO 10752:1998
ISO 10752:1994(E)
INTERNATIONAL STANDARD 0 ISO
Coal sizing equipment - Performance evaluation
ISO 1170: 1977, Coal and coke - Calculation of ana-
1 Scope
lyses to different bases.
This International Standard describes the principles
ISO 1213-1: 1993, Solid mineral fuels - Vocabulary -
and methods for the expression of results of per-
Part 1: Terms rela ting to coal preparation.
formante tests on sizing equipment used in coal
preparation, and includes methods for the evaluation
ISO 1953:i 972, Hard coals - Size analysis.
of Performance Parameters. Performance test pro-
cedures and size measurement techniques are rec-
ISO 1988:1975, Hard coal - Sampling.
ommended.
3 Definitions
This International Standard applies to all types of siz-
ing equipment, categorized as follows:
For the purposes of this International Standard, the
definitions given in 1213-1 and the following defi-
a) screens;
nitions apply.
b) classifiers;
3.1 General
c) others.
3.1.1 actual feed (F): Material fed to the sizing
equipment during the test period and including any
The procedure described in this International Standard
recirculated material.
applies to two-product Separations. Performance as-
sessment of multiproduct Separations tan be
3.1.2 coarser material: Material that is coarser than
achieved by consideration of a series of two-product
the reference size.
Separations.
3.1.3 finer material: Material that is finer than the
reference size.
3.1.4 product: Material discharged from the sizing
equipment Prior to any further treatment or recircu-
lation.
2 Normative references
3.1.5 coarser product (c): That product of size sep-
The following Standards contain provisions which,
aration that contains a greater Proportion of coarser
through reference in this text, constitute provisions
material than does the feed.
of this International Standard. At the time of publica-
tion, the editions indicated were valid. All Standards
3.1.6 finer product (f): That product of size separ-
are subject to revision, and Parties to agreements
ation that contains a greater Proportion of finer ma-
based on this International Standard are encouraged
terial than does the feed.
to investigate the possibility of applying the most re-
3.1.7 sharpness of Separation: An assessment of
cent editions of the Standards indicated below.
the deviation from a perfett Separation, usually ex-
Members of IEC and ISO maintain registers of cur-
pressed in terms of mean probable error (&.,).
rently valid International Standards.
1

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SIST ISO 10752:1998
ISO 10752:1994(E) 0 ISO
3.2 Performance Parameters the reference size, preferably expressed as both
b)
partition size and equal errors size;
3.2.1 theoretical yield (sizing): The maximum yield
NOTE 5 It is recognized that partition size is not al-
of a product at a reference size, as determined from
ways obtainable from the results of a size Separation
the size distribution curve for the reconstituted feed.
and that an alternative reference size therefore has to
be employed. To allow comprehensive comparison of
3.2.2 coarser material placement eff iciency (EC) :
Performance, it is recommended that Parameters based
The percentage of coarser material in the reconsti-
on equal errors size as the reference be included, in
tuted feed that reports to the coarser product.
addition to those based on partition size.
3.2.3 finer material placement efficiency (~5,): The
the sharpness of Separation, expressed in terms
d
percentage of finer material in the reconstituted feed
of probable error;
that reports to the finer product.
the distribution of misplaced material in each
d)
3.2.4 Overall Separation index: The sum of the product, presented graphically with respect to
coarser material placement efficiency and the finer size, and the particular values of misplaced ma-
material placement efficiency minus 100. terial in each product on both feed and product
bases, each determined at the reference size of
Separation;
4 Performance criteria
e) the material placement efficiencies expressed as
The following criteria should be determined where
applicable: coarser material placement efficiency (EC),
1)
finer material placement efficiency (EJ,
a) feed rate; 2)
Overall Separation index derived from 1) and
reference size of Separation; 3)
b)
.
2) I
sharpness of Separation;
d
the degree of difficulty of Separation, expressed
misplaced material;
d) in terms of near-size material;
material placement efficiencies;
e) other relevant characteristics of the feed material.
9)
the degree of difficulty of Separation;
Performance test procedures
6
g) material characteristics.
-rI
I ne equipment to be tested, the actual feed compo-
NOTES
sition, and the means of handling the feed and prod-
1 Th e above criteria will be in fluenced by test conditions ucts vary widely. A Single Standard procedure is not
which should therefore be fully reported.
applicable. The following general recommendations
are made.
2 lt is essential that p rediction of Separation results takes
into a ccount the nfluen ce of test conditions.
a) The average feed rate and/or product flow rates
should be determined by the most accurate
itions are made
3 lt is essential that test cond compatible
method possible in the particular circumstances.
to ensure valid compa risons.
Typical procedures that may be used are
4 Conditions should be kept uniform during a test.
1) direct assessment of the mass and/or volume
of the whole of the feed or product during the
5 Performance Parameters test;
For the Standard expression of Performance of a sep- 2) continuous assessment by means of a cali-
aration, the criteria in clause 4 should be determined brated belt weigher or flowmeter and inte-
by the following Parameters: gration during the test;
3) weighing timed increments taken at regular
a) the feed rate, expressed on mass and/or volume
bases; intervals during the test.
2

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SIST ISO 10752:1998
0 ISO
ISO 10752:1994(E)
b) Samples should be taken from the actual feed and 2) In circumstances that prevent the weighing
from each of the products. Sampling techniques, of sufficient streams, size analyses of feed
initial number of increments and minimum mass and products tan be used to determine the
of each increment should be Chosen so that all percentage yield of each product, as de-
scribed in annex A.
samples taken are representative. Sampling tech-
niques, initial number of increments and minimum
NOTE 12 In all circumstances, the method used to de-
mass of increment for solids being conveyed by
termine the actual yield of each product should be reported
a fluid should comply with existing International
with each respective value in table3.
Standards if available; for solids under other con-
ditions, ISO 1988 applies.
7 Analytical procedures
Representative samples should be taken
NOTE 6
from all relevant streams to and from the equipment to
The method and procedure of size analysis should be
be tested, to facilitate checking of results and assess-
selected, as far as possible, to be in agreement with
ment of the effects of degradation.
the principle of the equipment under test, to produce
c) lt is essential to determine the feed rate and the
results in compatible terms. For example, the results
actual yield of each product on a dry basis in ac- of size analysis by sieving would be compatible with
cordante with ISO 1170. This should be achieved vibrating screens, and the results of size analysis by
in accordance with one of the following pro- a series of small cyclones would be compatible with
cedures. cyclone separators. Size analysis by sieving should be
carried out in accordance with ISO 1953. The method
1) The mass of each product should be deter-
and apparatus used, and the basis of the percentages
mined by one or more of the following meth-
(by mass or volume), shall be stated in the data sheet
ods:
and in table 1.
a. direct weighing of the whole of each The feed Sample and each of the product samples
product collected over the duration of the should be subjected to size analyses in which the ratio
test or through continuous weighing and of the upper and lower size limits does not exceed
integration over the duration of the test; 2:l for each size fraction. lt is recommended that this
ratio for size limits be reduced to 2 :l for a mini-
Ir
b. taking regular timed increments over the
mum of two fractions, both above and below the ref-
duration of the test;
erence srze.
NOTES
C. weighing each product collected simul-
taneously over a selected timed period
13 In some circumstances, a ratio of size limits closer than
during the test.
2 :1 may be necessary in the region of the reference size,
J-
to ensure that each of the size fractions contains not more
NOTES
than 10 % of the Sample.
7 The methods given in 1) are listed in Order of
14 Size distribution curves for the products tan be used
reliability.
for
8 If it is feasible to measure both the mass of the
providing data for additional partition coefficients;
a)
feed (by belt weigher, weigh hopper, flowmeter,
etc.) and the mass of the products, this provides a
b) averaging analytically determined values to improve the
check.
derived partition curve.
9 If the mass of one of the products cannot be
measured, it tan be obtained from a mass balance
between the feed and products.
8 Evaluation and presentation of
Performance characteristics
10 Where the solids are conveyed by a fluid, it
may be more convenient to make volumetric
measurements.
8.1 General
11 Representative samples should be taken from
All data shall be evaluated and presented in one data
relevant streams to determine moisture contents
sheet, three tables and three figures as follows:
or concentrations of solids as appropriate, so that
the results tan be reported on a dry basis.
data sheet - test and equipment data;
a)

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SIST ISO 10752:1998
Q ISO
ISO 10752:1994(E)
size distribution of feed and products;
b) table 1 - 8.4 Partition curve
table 2 - partition coefficients and misplaced
d
The partition curve is constructed as shown in
material data;
figure 1, by plotting the value of each partition co-
efficient against the corresponding mean size. lt is
d) table3 - Statement of sizing equipment per-
recommended that each size fraction be represented
formante;
by its geometric mean size. Geometrie mean sizes
and partition coefficients are calculated in table 2, col-
figure 1 - partition curve;
e)
umns 13 and 14. The recommended scales are
figure2 - size distribution curve for the recon-
f )
size: log,, 1 cycle = 50 mm
stituted feed;
partition coefficient: 1 % = 2 mm
figure3 - misplaced material curves.
9)
NOTES
The presentation of the test data may be accom-
19 As an alternative to geometric mean size, each size
plished by the procedure described below. The
fraction may be represented by its mid-mass particle size,
specified tabular and graphical formats are given in
derived from a known functional relationship or estimated
clause 9. Specific worked examples are included in
from the reconstituted feed curve.
annexes B, C and D.
20 As an alternative method of construction, partition co-
NOTES
efficients tan be plotted as a histogram on a reconstituted
feed base, producing an area representative of mass. An
15 Primary calculation procedures are shown in tables 1
intermediate curve is then drawn by equalizing areas within
and 2. A column number in parentheses denotes a respec-
each size fraction. Performance Parameters are derived by
tive value taken from that column.
applying values obtained from the intermediate curve to the
size distribution curve for the reconstituted feed.
16 The origins of plotted values are shown in figures 1 and
reference to table and column numbers.
2 bY
8.5 Partition size
-17 Reference to definitions of Performance Parameters in
clause 3 supports the brief explanation of their derivation
The partition size, S,,, is obtained directly from the
given in relevant subclauses and in tables 1 and 2.
partition curve and is entered as a Performance par-
ameter in the Statement of sizing equipment per-
formante in table 3.
8.2 Basic data
NOTE 21 The partition size tan be determined from the
misplaced material curves (figure3) at the minimum value
The data obtained from a Performance test comprise of total misplaced material.
the size analyses of the actual feed and the coarser
and finer products and the proportion of material re-
86 . Sharpness of Separation
porting to each product. These basic data are com-
piled in table 1, columns 1 to 8, and calculated on a
The 25 %, &, and 75 %, & intercepts are each read
reconstituted feed basis in columns 9 to 12.
from the partition curve (figure 1) and are entered as
primary Parameters in the Statement of sizing equip-
ment Performance in table3. For symmetrical partition
curves, the sharpness of Separation may be ex-
8.3 Reconstituted feed size distribution
pressed in terms of the mean probable error (Z&,,) as
follows:
The size distribution curve for the reconstituted feed
S75 - s25
is constructed as shown in figure 2, by plotting the
. . .
E
(1)
pm =
2
cumulative percent less than the upper size limit (col-
umn 12 of table 1) against the upper size limit
In the more common case of skewed partition curves,
(column 1 of table 1).
the sharpness of Separation may be expressed in
terms of the upper and lower probable errors as fol-
NOTE 18 It is convenient to use a logarithmic scale for
lows:
particle size when plotting size distribution curves, to cover
a wide range of sizes and to cater for size Iimits that are in
Upper probable error = S75 - S,,
geometric Progression.
4

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SIST ISO 10752:1998
0 ISO
ISO 10752:1994(E)
Lower probable error = S,, - SZ, 8.9 Equal errors size
The upper probable error and lower probable error
Parameters may be used separately if one of the in-
tercepts is undefined.
The equal errors size (Se) is determined by reading the
size that corresponds to the Point of intersection of
the misplaced material curves for coarser and finer
products. Alternatively, the equal errors size tan be
8.7 Misplaced material curves
determined from the size distribution curve for the
reconstituted feed, as the size corresponding to the
The misplaced materials in the coarser and finer
yield of the finer product. The equal errors size is en-
products are calculated, as a percentage of the re-
tered into the Statement of sizing equipment per-
constituted feed, in table 2, columns 15 and 16. Cor-
formante in table 3.
responding values are summed to give total
misplaced material tabulated in column 17 of table 2.
The misplaced material cutves are constructed, as
shown in figure3, by plotting values for coarser prod-
ucts (column 15 of table 2), finer products (column 16
of table 2) and total misplaced materials (column 17
of table2), each against the corresponding upper size
8.10 Theoretical yield
limit S, (column 1 of table 1. The recommended scales
are
size: log,, 1 cycle = 50 mm
The theoretical yield value at the reference size, or
sizes, is determined, for each of the products, from
misplaced material: 1 % = 5 mm
the size distribution curve for the reconstituted feed.
NOTE 22 If it is necessary to use an alternative scale, this
Alternatively, each respective theoretical yield value
should be a simple multiple of the recommended scale; for
tan be determined by subtracting the misplaced ma-
an example see annex C, figure C.3.
terial in the product under consideration from the ac-
tual yield (Y, or Yf) and adding the misplaced material
in the complementary product.
8.8 Misplaced material
EXAMPLE
. . .
Y e+=Yc--Mc+Mf
(2)
The misplaced material is read from each respective brk
curve at the reference size, or sizes (see note 23), and
the values are entered into the Statement of sizing where
equipment Performance in table3. The value of mis-
Y is the theoretical yield of the coarser
placed material for each respective product is con-
c,t
product;
verted to a percentage of that product (see note 24),
and the converted values are entered into the state-
is the yield value of the coarser product;
Yc
ment in table3.
is the misplaced material in the coarser
MC
NOTES
product;
23 lt is convenient to construct an Ordinate on the curves,
is the misplaced material in the finer prod-
at the reference size, or sizes, being considered (e.g. &
uct.
&, S,), to assist in reading the three intercepting misplaced
values.
Theoretical yield values are entered into the state-
24 All values of misplaced material obtained from the
ment of sizing equipment Performance in table3.
curves are in terms of percentages of the reconstituted
feed. Conversion to percentage of the respective product NOTES
tan be obtained by multiplying the corresponding curve by
26 Misplaced materi al values are in terms of percentages
100 and dividing by the yield value of the product under
consideration (i.e. Yc or Yf>. of reconstituted feed.
25 The procedure tan be repeated for any other reference 27 The theoretical yield of the complementary product tan
size. be obtained by differente from 100 %.
5

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SIST ISO 10752:1998
ISO 10752:1994(E) 0 ISO
Other relevant characteristics of the feed material that
8.11 Material placement eff iciency
influence the degree of difficulty of Separation are
entered into the test and equipment data sheet,
Material placement efficiencies are evaluated and en-
which varies according to the type of equipment un-
tered into the Statement of sizing equipment per-
der consideration. Examples of data sheets are given
formante in table3. The calculations are as follows.
in annexes B, C and D.
Coarser material placement efficiency (EC)
a)
8.13 Test and equipment data
Yc - Mc
x 100 . . .
(3)
EC= y
c,t
The presentation of the results of Performance tests
on coal sizing equipment shall include a report of the
defined in 8.10 .
where Yc, Mc and Yc t are as
I
equipment details, test conditions and characteristics
of the feed material, particularly those that influence
Finer material placement efficiency (E,)
b)
the degree of difficulty involved in the Separation. This
information is entered into the test and equipment
Yf - Mf
=-x 100 . . .
(4)
Ef
data sheet. Since the Parameters involved will vary for
Yf,t
different categories of equipment, a specimen of the
data sheet is not included in the general illustration,
but models are presented in the specific worked ex-
is the yield value of the finer product; amples given in annexes B, C and D.
is the theoretical yield of the finer
Yr,t
9 Tabular and graphical presentation
product;
Blank tables and specimen figures are given. The use
is as defined in 8.10.
of these is illustrated in annexes B, C and D. The or-
der of presentation shall be as follows:
c) Overall Separation index (Si)
. . .
Si = Ef + EC - 100
(5)
a) data sheet - test and equipment data (see
8.13);
NOTES
table 1 - size distribution of feed and products;
b)
28 Misplaced material values are in terms of percentage
of reconstituted feed.
partition coefficients and misplaced
Cl table 2 -
material data;
e for the evaluation of
29 Alternative methods are availabl
the material placement efficiencies.
figure 1 - partition curve;
d)
8.12 Near-size material
figure2 - size distribution curve for the recon-
e)
stituted feed;
The near-size material, i.e. material within + 25 % of
the reference size or sizes, is determined from the
figure3 - misplaced material curves;
f )
size distribution curve for the reconstituted feed in
figure 2, and is entered into the Statement of sizing g) table3 - Statement of sizing equipment per-
formante.
equipment Performance in table 3.

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SIST ISO 10752:1998
ISO m752:1994(E)
- Size distribution of feed and products
Table 1
t
E
w
c
E
w
E
E
a
.-
E
.I
-
8
N
6
P
iz
3

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SIST ISO 10752:1998
ISO 10752:1994(E)
Q ISO
Table 2 - Partition coefficients and misplaced material data
13 14 1 15 16 17
Size limit Misplaced material
Partition
Geometrie coefficient mm (as a percentage of the reconstituted feed)
mean size (to coarser
Coarser product Finer product
product)
Total
UPPer
Cumulative percent Cumulative percent
mm %
less than S, greater than S,
(9)
x 100
c (IO) 12’
Sl 22 (9) f ‘)
j/GF - ( ‘5) + ( ‘6)
(1 ’)
Note - A column number in parentheses denotes a respective value taken from a column in this table or table 1.
1) Summation to considered value of S, (in column 1 of table 1) from S, equal to Zero.
2) Summation from considered value of S, (in column 2 of table 1) to S, equal to Zero.

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SIST ISO 10752:1998
Partition coefficient, %
(sec table 2, column 14)
2 W
c1) N
0
0 Vi 0
‘TI
-.
r
is
4
I
s
c1
-.
$
Cu2
3E
3fD
-
2
$3
3
3
I I I I I I I I l I I I I I I I
I l *
I I I 1 I I I I ! ! ! I I I I I I ! I
t
I I I I I I I 1 I I I I I I I I I 1 I
0’
0

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SIST ISO 10752:1998
Cumulative percent Less than upper size Limit
kee table 1, column 12)
h) W Ul
0
m
-0 $ 0 0 z 0 z 2 g 0 0
U
i
n
II.
I
m

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SIST ISO 10752:1998

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SIST ISO 10752:1998
ISO 10752:1994(E)
Table 3 - Statement of sizing equipment Performance
Determined values
Performance Parameters
Partition curve
Partition size:
S50
25 % Intercept:
s25
75 % Intercept:
S75
s75 - s25
Mean probable error:
Upper probable error:
(s 75 - s50)
Lower probable error:
(s 50- s 25 >
Misplaced material curves
Equal errors size:
Percentage of feed
Percentage of product
(reconstituted)
Misplaced material in coarser product (M,)
at S50
at designated size (Sd)
Misplaced material in finer product (M,)
at S50
at designated size (SJ
Total misplaced material
at s50
at designated size (SJ
at Se
Method of determination
Product yield and material placement efficiencies
Actual yield of coarser product:
Actual yield of finer product:
at Se
at Sd
Y
Theoretical yield of coarser product:
c,t
Theoretical yield of finer product:
Yr,t
Coarser material placement efficiency:
EC
Finer material placement efficiency:
Ef
Overall Separation index:
4
Degree of difficuity involved
Near-size material
12

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SIST ISO 10752:1998
ISO 10752:1994(E)
Annex A
(normative)
Calculation of the yield of each product of a size Separation from size
analyses of feed and product materials
is the percentage of the ith fraction in the
A.l Introduction
actual feed;
Clause 6 lists the methods recommended, in Order
if(@ is the percentage of the ith fraction in the
of reliability, for the determination of the yields of the
reconstituted feed;
coarser product (Y,) and the finer product (Yf) of a size
Separation.
is the percentage of the ith fraction in the
r;
finer product;
Clause 6 also describes the circumstances under
.
which these yield values may be calculated from the
is the percentage of the ith fraction in the
k
size analyses of the actual feed and the product ma-
coarser product.
terials. The two methods recommended are each
based on the principle of least-squares and are out-
A.2.2
Calculation of yield values from
lined in A.2 .
cumulative size analyses
lt is recognized that several methods exist for the
This method is based on a least-squares principle, the
calculation of the yield values, and each tan be used
yield values being calculated so that the sum of the
with careful interpretation. The recommendations are,
squared deviations between the reconstituted feed
however, based on test work carried out under care-
and the actual feed size fractions, taken in terms of
fully controlled conditions where comparison was
the actual feed size fraction, is at a minimum.
made between yield values calculated by several of
the available methods, using directly determined val-
Thus:
ues as the Standard for comparison.
More sophisticated methods, involving the use of
(A.1)
Computer programs, are being developed, some of
which are already available. Use of these methods tan
-.
Since
sometimes be justified by the nature of the work in-
volved. Such methods are under review for possib
...