CEN/TR 14061:2021

SLOVENSKI STANDARD
01-november-2021
Nadomešča:
SIST CR 14061:2002
Gnojila - Določanje količine prahu
Fertilizers - Determination of dust content
Düngemittel - Bestimmung des Staubgehaltes
Engrais - Détermination de la teneur en poussière
Ta slovenski standard je istoveten z: CEN/TR 14061:2021
ICS:
65.080 Gnojila Fertilizers
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

CEN/TR 14061
TECHNICAL REPORT
RAPPORT TECHNIQUE
June 2021
TECHNISCHER BERICHT
ICS 65.080 Supersedes CR 14061:2000
English Version
Fertilizers - Determination of dust content
Engrais - Détermination de la teneur en poussière Düngemittel - Bestimmung des Staubgehaltes

This Technical Report was approved by CEN on 23 May 2021. It has been drawn up by the Technical Committee CEN/TC 260.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2021 CEN All rights of exploitation in any form and by any means reserved Ref. No. CEN/TR 14061:2021 E
worldwide for CEN national Members.

Contents Page
European foreword . 3
Introduction . 4
1 Scope . 5
2 Normative references . 5
3 Terms and definitions . 5
4 Symbols and abbreviated terms . 5
4.1 Technical Symbols . 5
4.2 Statistical symbols and abbreviations . 6
5 Calculation of the spouting bed apparatus . 6
5.1 Particle terminal velocity . 6
5.2 Spouting section . 7
5.3 Maximum spoutable bed height . 7
5.4 Design of apparatus . 7
5.5 Flowmeter . 8
6 Initial testing . 8
6.1 Determination of dust weight . 8
6.2 Setting the test time . 8
6.3 Preliminary ringtests . 8
7 Conclusive ring test . 9
7.1 General. 9
7.2 Apparatus . 9
7.3 Sample preparation . 9
7.4 Procedure, test plan . 9
7.5 Statistical methods . 9
7.5.1 Statistical model . 9
7.5.2 Outliers . 9
7.5.3 Regression analysis . 9
7.5.4 Correction for adapter-effect . 9
7.5.5 ANOVA-analysis . 9
7.6 Statistical analysis of test data . 10
7.6.1 Deviation from test plan . 10
7.6.2 Example — granulated NPK . 10
7.6.3 Summary of ANOVA . 14
8 Other methods . 15
9 Conclusion . 15
Annex A (informative) Method for the determination of dust potential . 16
Annex B (informative) Optical methods for determination of fertilizer dust . 22
Bibliography . 23

European foreword
This document (CEN/TR 14061:2021) has been prepared by Technical Committee CEN/TC 260
“Fertilizers and liming materials”, the secretariat of which is held by DIN.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
This document supersedes CR 14061:2000.
Significant changes between this document and CR 14061:2000 are as follows:
a) modification of the figures to contain neutral language;
b) adaption to current principles and rules for structure and drafting.
This document is published by the European Committee for Standardization. It is published for
information only and does not have the status of a European Standard.
The Annexes A and B are informative.
Introduction
0.1 General
In production and handling of fertilizers dust generation is of great concern by both producers and users
of the fertilizer products. For health and environmental reasons, it is of great interest to control and
reduce the amount of dust generation. In the fertilizer industries there are a wide variety of apparatus
for dust determination, most being used as “in-house” methods in plants and laboratories.
The content of this document was developed by CEN/TC 260/WG 2 between 1991 and 2000 in order to
develop a standard dust test. A spouting bed apparatus was designed for gravimetric determination of
dust, and after two preliminary ringtests a conclusive ringtest involving six laboratories was carried out.
Not being able to develop a statistical significant method for the determination of dust, TC 260 decided
by resolution 105/1997 to change the deliverable of this work item into a CEN Technical Report. The
change of deliverable has been approved by CEN/BT with its resolution BT C172/1999.
0.2 General background
When handling fertilizer grains, dust is at every moment generated on the surface. The fertilizer thus
contains more or less free dust, and has a potential for generating more dust (abrasion dust) when subject
to subsequent handling.
In all existing gravitational test methods dust will be generated during the testing time, and the two types
of dust will be measured simultaneously. The scope of the method is expressed in Annex A and the aim is
to:
“.specify a method for the determination of the dust potential of solid fertilizers and is applicable to
granular and prilled fertilizers.
Dust particles, which cause reduced visibility in air are too small to be determined by this method.”
0.3 Background for choice of method
Fluidized particle powders are generally divided into four characterizing groups (A, B, C, D) [1]. Group C
particles are small, cohesive and are difficult to fluidize. Aeratable powders belong to group A, and many
fluidized bed catalysts characterize this group. Sand typifies group B, in which inter-particle forces are
negligible, in contrast with group A powders. Large and/or dense particles in general belong to group D,
and fertilizer particles (2 mm to 4 mm) in air are in this group. A flow diagram can be used to broadly
identify flow regimes appropriate to combinations of gas velocity and particle properties. It can be shown
that the fertilizer system is in the lower part of the spouted bed regime.
A criterion that can be used to distinguish between group B and D is the numerical inequality that
classifies a powder as spoutable if:
1,24
(ρ – ρ ) ⋅ d > 0,23
p f p
For a typical fertilizer this value will be about 1,4 and about 0,5 for an urea prill.
From previous experiments with other methods based on a fluidized bed and the above calculations, it
was decided to base the method upon the spouted bed principle.
1 Scope
This document is applicable to the determination of dust potential of solid fertilizer, obtained in prilling
or granulation process. Compacted or crystalline materials were not considered.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
No terms and definitions are listed in this document.
ISO and IEC maintain terminological 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/
4 Symbols and abbreviated terms
4.1 Technical Symbols
C drag coefficient
D
d particle diameter, expressed in metres (m)
p
d average spout diameter, expressed in metres (m)
s
D average particle diameter, expressed in metres (m)
p
D diameter of spouting section, expressed in metres (m)
D inner orifice diameter, expressed in metres (m)
i
g gravity, expressed in kilograms per metres per square seconds (kg/m s )
H bed height, expressed in metres (m)
Re Reynolds number
v terminal velocity, expressed in metres per seconds (m/s)
t
v minimum spouting height
ms
ρ particle density, expressed in kilograms per metres to the third power (kg/m )
p
ρ fluid density, expressed in kilograms per metres to the third power (kg/m )
f
μ viscosity, expressed in Newton seconds per square metres (Ns/m )
4.2 Statistical symbols and abbreviations
df degrees of freedom
F mean square between groups/mean square within groups
F tabulated value form the F-distribution for a significance level of 0,05 confidence interval
crit
MS mean square
P-value significance level corresponding to a given F (should be less than 0,05 to reject the null-
hypothesis)
SS sum of squares
5 Calculation of the spouting bed apparatus
5.1 Particle terminal velocity
A particle falling freely in a fluid will finally reach its terminal velocity. The forces acting on it are
gravitational, accelerating, buoyancy force and drag (friction) force. The drag force can be expressed by
a drag coefficient C , which is expressed by Formula (1):
D
ρρ− dg
( )
p f p
C = (1)
D
ρ v
ft
By calculation and plotting log C against log Re (Reynolds number) the so-called “standard drag-curve”
D
can be obtained which has three broad regions:
— Laminar region, Re < 0,2;
— Transitional region (tr), 0,2 < Retr < 1000;
— Turbulent region, Re > 1000.
2 2 2 2
The drag coefficient equation can be multiplied with ρ v d /μ and rearranged as:
f t p
ρρ− dg
( )
p f p
C Re =  (2)
D t
µ
The group C Re is dimensionless containing only the physical properties of the particle/fluid system
D tr
including the particle diameter d . The Re-number and the terminal velocity (v ) can be estimated by
p t
graphical methods.
Calculations prove that transitional flow describes the system of fertilizer dust in air, thus giving Table 1.
Table 1 — System of fertilizer dust in air
Particle size d C Re Re v
p D tr tr t
µm   m/s
100 88 3,0 0,5
150 300 7,7 0,8
200 704 15,0 1,3
-----------------
...