ISO 5146:2023

INTERNATIONAL ISO
STANDARD 5146
First edition
2023-11
Coal and coke — Coal preparation
plant — Density tracer testing for
measuring performances of coal
density separators
Charbon et coke — Installation de préparation du charbon —
Essais des traceurs de densité pour la mesure des performances des
séparateurs de charbon en fonction de la densité
Reference number
© ISO 2023
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ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Test method . 2
4.1 General . 2
4.2 Apparatus . 2
4.2.1 Density tracers . 2
4.2.2 Density tracer retrieval or detection equipment . 3
4.3 Procedure . 3
4.3.1 Density tracer selection . 3
4.3.2 Insertion of density tracers . 3
4.3.3 Density tracer retrieval or detection and data capture . 5
4.4 Data processing. 5
4.4.1 Data acceptability . 5
4.4.2 Calculation of partition coefficients . 7
4.4.3 Confidence intervals for partition points. 7
4.4.4 Two forms of the partition curve. 8
4.4.5 Fitting the partition curves . 9
4.4.6 Asymmetry factor for 5-parameter logistic . 10
4.5 Test report . 10
Annex A (informative) Density tracer properties .14
Annex B (informative) Test duration and aids for density tracer retrieval or detection .16
Annex C (informative) Selection of density tracers .19
Annex D (informative) Density tracer test report template .21
Annex E (informative) Interpretation of partition curves .24
Annex F (normative) Working with partition coefficients to floats .26
Annex G (informative) Formulae in linear format .27
Bibliography .28
iii
Foreword
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Coal preparation: Terminology and performance.
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iv
Introduction
The objective of this document is to provide the coal preparation industry with an accurate, safe, rapid
and site-based method for determining the density partitioning performances of density separators
and, to utilize statistical and mathematical procedures to avoid personal biases in fitting partition
curves to the observed data. To meet the second objective, this document includes formulae which can
be incorporated in a user spreadsheet.
v
INTERNATIONAL STANDARD ISO 5146:2023(E)
Coal and coke — Coal preparation plant — Density tracer
testing for measuring performances of coal density
separators
1 Scope
This document specifies the requirements for testing the performances of coal density separators using
density tracers and provides a method for the presentation of test results.
This document is partly based on AS 5213.
This document is applicable to dense medium cyclones (DMCs) and dense medium baths, as follows:
a) for a single separator;
b) for a group of separators where the feed is distributed between them at a point downstream of
density tracer insertion;
c) for density tracers of any size; but rarely used for particles with maximum dimension less than
2 mm.
This document also provides guidance for testing the performances of other types of density separators
with density tracers.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
AS 2418, Coal and coke — Glossary of terms
3 Terms and definitions
For the purposes of this document, the terms and definitions given in AS 2418 and the following apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
cut-off time
time which follows the time of last density tracer (3.3) insertion (3.5) by 5 min plus the greater of floats
transit time or sinks transit time
Note 1 to entry: Floats transit time is the average time in minutes since insertion into a separator feed for particles
collected from, or detected in, a separator floats stream. Sinks transit time is the average time in minutes since
insertion into a separator feed for particles collected from, or detected in, a separator sinks stream.
3.2
density separator
device for the cleaning of coal, in which particles are separated into two or more streams according to
their densities
3.3
density tracer
non-porous particle of defined shape and density that is not easily broken or abraded
Note 1 to entry: Types include radio frequency identified (RFID) density tracers and non-RFID recoverable
density tracers.
3.4
average probable deviation
écart probable moyen
E
pm
half of the difference between the densities corresponding to the 75 % and 25 % partition coefficients
as obtained from the partition curve
3.5
insertion
placement of a density tracer (3.3) into a separator feed stream, typically by dropping into a feed
preparation screen oversize launder
4 Test method
4.1 General
The test method specified in 4.2 to 4.5 covers the following:
a) generation and capture of density tracer test data utilizing either:
1) retrieved, re-usable non-RFID density tracers; or
2) automatically detected RFID density tracers;
b) use of those data to estimate density partition coefficients;
c) presentation of those data and results in tabular and graphical forms;
d) fitting one of two alternative mathematical forms for the partition curve to the density partition
coefficients;
e) determination, from the partition curves, of key partitioning criteria.
4.2 Apparatus
4.2.1 Density tracers
For the purposes of this document, density tracers shall have the following properties:
a) shape and dimensions: any that can be fully described in the density tracer test report;
EXAMPLE Cubic, with edge length 13 mm.
b) tolerance on dimensions: 100 % within ±10 % of nominal;
c) nominal densities: any;
d) tolerances on density, for cubic tracers of 8 mm edge length and larger:
1) for nominal relative density (RD) values up to 1,60: 99 % within ±0,006 RD of the nominal
value;
2) for nominal RD values greater than 1,60: 99 % within ±0,011 RD of the nominal value.
e) density designation:
1) non-RFID density tracers: by engraving or colour-coding;
2) RFID density tracers: electronically written to an internal memory chip.
NOTE See Annex A for details of suitable density tracers.
4.2.2 Density tracer retrieval or detection equipment
If a test is to be conducted using non-RFID density tracers, apparatus for use as aids for retrieval shall
be suitable for the circumstances (see Annex B).
If a test is to be conducted using RFID density tracers, radio equipment shall be present for retrieval
of data from each density tracer in the floats and sinks streams from the density separator(s) (see
Annex B).
4.3 Procedure
4.3.1 Density tracer selection
Density tracer selection shall be as follows.
a) Decide on one or more nominal sizes.
b) For each nominal size, decide the nominal densities (guidance is provided in Annex C).
c) For each nominal size, decide the number of density tracers to be used at each nominal density,
being:
1) no less than 30;
2) equal to the number selected at every other nominal density.
d) Assemble those density tracers.
4.3.2 Insertion of density tracers
The following procedure shall be used for the insertion of density tracers.
a) Decide on the insertion point and required test duration and calculate the required interval
between density tracer insertions as the test duration in seconds divided by the total number of
density tracers selected.
NOTE Annex B provides further information on test durations.
b) Ensure that retrieval personnel or detection equipment are in place and activated.
c) Record the time at which the first density tracer was inserted.
d) At approximately the calculated intervals, insert or drop the density tracers into the feed stream
of the density separator(s) to be tested (see Figure 1), either manually or using a mechanical
dispenser. The density order of density tracer insertions shall be either:
1) pseudo-random, by mixing the selected density tracers prior to one-by one selection and
insertion; or
2) following a protocol whereby one density tracer of every selected size and density is inserted,
one-by-1, followed by a second density tracer of every selected size and density, etc.
e) Record the time at which the last density tracer was inserted.
Unplanned interruptions to plant feed of up to 10 min duration can be tolerated, but tracer insertion
shall be stopped, restarted when feed is resumed and documented.
Figure 1 shows typical locations for the insertion of density tracers and for the retrieval or detection of
density tracers.
Key
1 real-time display of partition curve 7 DMC module
2 typically, density tracers would be added here 8 non-radio density tracers would be retrieved here
3 medium 9 sinks drain and rinse screen
4 de-sliming screen 10 floats drain and rinse screen
5 sump or wing tank 11 detectors for radio density tracers
6 pump
NOTE 1 This is a simplified typical flowsheet showing points of addition and retrieval of density tracers.
NOTE 2 In this case, the separator is a dense medium cyclone.
NOTE 3 For RFID density tracers, alternative locations for detectors are at the drain-and-rinse screens.
Figure 1 — Example of a simplified density separator flowsheet
4.3.3 Density tracer retrieval or detection and data capture
4.3.3.1 Non-RFID density tracers
The procedure shall be as follows.
a) Retrieve density tracers from the material on the floats drain and rinse screen(s) (see Figure 1) by
hand or using a scoop or net or magnets. Place them in one or more containers marked “Floats” (see
Figure 1, NOTES 1, 2 and 3).
b) Retrieve density tracers from the material on the sinks drain and rinse screen(s) by hand or using
a scoop or net or magnets. Place them in one or more containers marked “Sinks” (see Figure 1,
NOTES 1, 2 and 3).
c) Sort the density tracers retrieved from floats before the cut-off time according to their densities
and record the number for each density.
d) Sort the density tracers retrieved from sinks before the cut-off time according to their densities
and record the number for each density.
In some circuits, screens cannot be readily accessed for density tracer retrieval, and alternative
retrieval points should be sought. For example, primary density separator sinks may be fed directly to
a secondary density separator without passing a drain-and-rinse screen. In that case, density tracers
retrieved from secondary density separator floats and sinks should be reported as primary density
separator sinks.
Any density tracers retrieved from the screens after the cut-off time should not be included in the test
data.
If the density tracers are to be retrieved by magnets, they should be ferromagnetic.
4.3.3.2 Automatically detected RFID density tracers
The procedure shall be as follows.
a) Detect and record the densities of RFID density tracers in the floats stream using RFID apparatus
located downstream of the density separator (see Figure 1). In some cases, circuit configuration
may dictate that two or more detection points are required.
b) Detect and record the densities of RFID density tracers in the sinks stream using RFID apparatus
located downstream of the density separator (see Figure 1). In some cases, circuit configuration
may dictate that two or more detection points are required.
Any density tracers detected after the cut-off time shall not be included in the test data.
If access to suitable locations for detector placement is limited, alternative locations should be sought.
For example, primary density separator sinks may be fed directly to a secondary density separator
without passing a conveyor. In that case, density tracers retrieved from both floats and sinks of a
secondary density separator should be reported as primary density separator sinks.
4.4 Data processing
4.4.1 Data acceptability
4.4.1.1 Selection of tracer densities
To be acceptable, the selected density tracer densities shall include the following eight RDs from Table 1:
a) the four RDs which are closest to the d ;
b) at least one RD in the range 0,05 to 0,10 lower than the d (unless the d is less than 1,31 RD);
50 50
c) at least one RD in the range 0,05 to 0,10 higher than the d ;
d) at least one RD in the range 0,10 to 0,20 lower than the d (unless the d is less than 1,36 RD);
50 50
e) at least one RD in the range 0,10 to 0,20 higher than the d .
See Annex A for more information.
Table 1 — Typical densities and density tolerances of density tracers for coal operations (8 mm
and larger)
Nominal density Tolerance 99 % Nominal density Tolerance 99 % Nominal density Tolerance 99 %
RD units RD units RD units RD units RD units RD units
1,26 ±0,006 1,44 ±0,006 1,62 ±0,011
1,27 ±0,006 1,45 ±0,006 1,64 ±0,011
1,28 ±0,006 1,46 ±0,006 1,66 ±0,011
1,29 ±0,006 1,47 ±0,006 1,68 ±0,011
1,30 ±0,006 1,48 ±0,006 1,70 ±0,011
1,31 ±0,006 1,49 ±0,006 1,72 ±0,011
1,32 ±0,006 1,50 ±0,006 1,74 ±0,011
1,33 ±0,006 1,51 ±0,006 1,76 ±0,011
1,34 ±0,006 1,52 ±0,006 1,78 ±0,011
1,35 ±0,006 1,53 ±0,006 1,80 ±0,011
1,36 ±0,006 1,54 ±0,006 1,82 ±0,011
1,37 ±0,006 1,55 ±0,006 1,84 ±0,011
1,38 ±0,006 1,56 ±0,006 1,86 ±0,011
1,39 ±0,006 1,57 ±0,006 1,88 ±0,011
1,40 ±0,006 1,58 ±0,006 1,90 ±0,011
1,41 ±0,006 1,59 ±0,006 1,95 ±0,011
1,42 ±0,006 1,60 ±0,006 2,00 ±0,011
1,43 ±0,006 2,10 ±0,011
For density tracers smaller than 8 mm, cubes wider 99 % density tolerances may be accepted, but those
tolerances shall be determined and recorded on the density separator performance report.
4.4.1.2 Collection/detection rate
To comply with this document, the collection or detection rate for density tracers over all densities
employed shall be not less than 70 %.
NOTE 1 Tracer losses or non-detections influence the fitted curve parameters. For collection/detection rates
of 90 % or more, the data acceptability provisions are intended to achieve more than 95 % confidence that, by
ignoring those losses or non-detections, the fitted values of:
a) d will be changed by less than 0,01 RD; and
b) E will be changed by less than 25 %.
pm
NOTE 2 For collection/detection rates less than 90 % that confidence level (95 %) is likely to be
disproportionately reduced.
NOTE 3 The 25 % confidence level for E can also be reduced if E falls below about 50 % of the interval
pm pm
between adjacent tracer densities [e.g. below 0,005 (50 % of 0,010 RD)].
4.4.2 Calculation of partition coefficients
For each density tracer density employed in the test, calculate the observed partition coefficient, as a
percentage:
N
s
P =×100 (1)
o
NN+
()
sf
where
P is the observed partition coefficient to sinks;
o
N is the number of density tracers collected from or detected in sinks;
s
N is the number of density tracers collected from or detected in floats.
f
NOTE 1 The numerical factor 100 is used to convert the dimensionless partition coefficient to a percentage,
%.
Alternatively, partition coefficients may be expressed in terms of percent to floats. This requires a
number of changes in the procedures for calculating partition coefficients and for fitting the partition
curves; these are detailed in Annex F.
The conventional procedure for configuring partition curves with the abscissa in terms of percent to
sinks detailed in 4.4 to 4.5 shall be used. In case the relevant formulae on Clause 4 are not used, the
formulae in Annex F shall be used to configure partition curves in terms of percent to floats.
NOTE 2 Refer to ISO 923 for more information on partition coefficients.
4.4.3 Confidence intervals for partition points
4.4.3.1 Tracer densities
The 95 % confidence intervals for the RFID density tracers described in Table 1 shall be taken as:
a) ±0,005 RD for nominal RDs 1,30 to 1,60;
b) ±0,010 RD for other nominal densities.
4.4.3.2 Partition coefficients
4.4.3.2.1 General
For each selected RD, the lower and upper 95 % binomial confidence limits and the overall confidence
interval shall be calculated using Formulae (2) to (4) which are based on the inverse cumulative
distribution function for probability, p .
BETA.INV
4.4.3.2.2 Lower confidence limit, L
CL
Lp=×100 (2)
CL BETA.,INVN()00 25 ()N +1
sf
with the proviso that if the number collected or detected in sinks is zero, the lower confidence level
shall be zero.
4.4.3.2.3 Upper confidence limit, L
CU
Lp=×100 (3)
CU BETA.,INVN00 975 +1 N
()()
sf
with the proviso that if the number collected or detected in floats is zero, the upper confidence level
shall be 100.
4.4.3.2.4 Overall confidence interval, I
CO
IL=−L (4)
CO CU CL
NOTE 1 See Reference [2] for more information on confidence limits. Employing a spreadsheet function, and
for partition coefficients to sinks, examples of confidence limits for cases where 27 density tracers of one RD are
collected or detected are given in Table 2.
Table 2 — Examples of confidence limits
95 % confidence limits
Partition coefficient
N N
s f
estimate
Lower Upper Overall
0 27 0,0 0 12,8 12,8
15 12 55,6 35,3 74,5 39,2
27 0 100,0 87,3 100 12,7
NOTE 2 As an example for
...