Residual textile fibre content in granulates

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Residual textile fibre
content in granulates
Aliapur’s R&D department
has developed a reliable and
reproducible process for determining
textile fibre content in batches of
end-of-life-tyre granulates.
This process is currently being used
to help in establishing
an AFNOR standard.
Residual textile fibre content in granulates
Definition
Mass fraction of textile fibres contained in a laboratory sample of granulates obtained from end-of-life tyres.
Reference value
Residual content of loose textile fibres in granulates of between 0% and 0.3% in weight.
Origin of the textile fibres
The percentage of fibres in end-of-life tyres is between 0% and 6% of the weight of the tyres, depending on whether
they are from truck tyres or passenger car tyres.
Composition of an end-of-life truck tyre
Composition of an end-of-life passenger car tyre
Mass fraction
Mass fraction
Rubber between 75% and 80%
Rubber between 80% and 85%
Wire between
10% and 15%
Wire between
20% and 25%
Textile fibres 5%
For end-of-life tyres to be integrated into the various industrial production processes and thus recycled, they must
be of constant and optimum quality. After the various shredding phases, the textile fibres are removed from the
granulates by aspiration.
The presence of fibres in the end-of-life tyre granulates can be a problem in certain applications, for example
visually, or when the granulates are incorporated into binding agents that the fibres tend to absorb. It is thus
important to ensure that the textile fibre content is as low as possible.
Industrial production of
granulates
+
Shred
Granulates with maximum
0.3% textiles fibres
+
Wire with between
3 and 50%* of rubber
Textile fibres with
between 20 and 50%*
of rubber
* depending on which industrial process is used
Method recommended and studied by Aliapur
At Aliapur’s request, the BRGM1 adapted the ASTM D5603 – 01 standard to measure the textile fibre content
in a 500 g sample of granulates. In addition to the loose textile fibres, the laboratory technicians identified and
weighed the visible textile fibres still bound to the granulates. The laboratory confirmed the repeatability and
reproducibility of this method.
Illustration of the general principle
500 g of granulates
Remove from each sieve:
balls of loose textile fibres,
n textile fibres bound to granulates,
n granulates.
n
ELT granulates
Sifter
Operating method
Masses
Granulates
Sieve 1
m1 G
Loose fibres Bound fibres
m1 FLoose m1 FBound
Sieve 2
m2 G
m2 FLoose
m2 FBound
Sieve 3
m3 G
m3 FLooses
m3 FBound
Sieve 4
m4 G
m4 FLoose
m4 FBound
Sieve 5
m5 G
m5 FLoose
m5 FBound
Sieve 6
m6 G
m6 FLoose
m6 FBound
n First of all, carry out particle size distribution analyses in accordance with the standard XP T 47-752.
Remark: this characterization can be carried out in parallel with the particle size distribution analysis of the products.
n Manually remove from each sieve the loose textile fibres, as well as any textile fibres bound to granulates
(visible with the naked eye).
n Then weigh on scales the bound textile fibres, the loose textile fibres, the remaining granulates for each particle
size category.
Results
The measurements carried out on a dozen products
obtained from the sampling plan in accordance with the
“Samples and sampling” sheet, and from four different
sites (samples of 500 g of granulates) give fibre content
values of between 0% and 0.3% in weight.
Measurements of the bulk density of fibres produced the
following values: from 0.12 to 0.13 g/cm3 (standard
NF EN ISO 61 – Plastics – Determination of apparent
density of moulding material that cannot be poured from
a specified funnel.
(1) Bureau de Recherches Géologiques et Minières.
The concentration of granulates still bound to textile
fibres (visible with the naked eye) varies between 0%
and 5.4%. Studying the different products analysed
revealed the presence of granulates bound to fibres
essentially in granulates of more than 2 mm; below this
particle size, the concentration was very low.
This operating method is currently the subject of a study
with a view to establishing an AFNOR standard.
Conclusion
The processes for separating out textile fibres used in granulation factories make it possible to attain extremely
low free-textile content, or even no fibres. The measurements obtained give values for the residual fibre content
of between 0% and 0.3% in weight.
References
n Projet de norme expérimentale à l’étude – Pneus
usagés non réutilisables (PUNR) – Détermination
du taux de fibres textiles dans les granulats issus
de PUNR à l’issue de procédés de granulation –
Méthode basée sur une séparation manuelle après
tamisage mécanique des produits.
n ASTM D5603 – 01 Standard Classification
for Rubber Compounding Materials – Recycled
Vulcanizate Particulate Rubber.
Sample sites
Reference studies
“Échantillonnage et caractérisation de granulats
de pneus usagés non réutilisables – BRGM pour le
compte d’Aliapur – Juillet 2006”.
n
“Échantillonnage et caractérisation de granulats
de pneus usagés non réutilisables en vue de la
comparaison de différents procédés de granulation –
BRGM pour le compte d’Aliapur – Février 2007”.
n
“Analyses de granulats, de fibres textiles et de fibres
métalliques issus du broyage de PUNR véhicules
légers (VL) et poids lourds (PL) – LRCCP pour le compte
d’Aliapur – Juin 2005”.
n
The studies carried out by Aliapur used a variety
of batches of ELT granulates from four European
granulation factories using different processes and
raw materials. These batches correspond to the main
products marketed by these sites.
The four sites from which the samples were taken
collectively represent the main configurations of what
can be found in terms of processes and types of tyre
used. Aliapur used a wide variety of products for its
analyses, guaranteeing an overall view of the sector
and good representativeness of the results.
n
n
n
n
1
Factory 1: successive shredding of truck tyres.
F actory 2: successive shredding of passenger car
tyres.
F actory 3: shredding by crushing of truck and
passenger car tyres.
F actory 4: cryogenics followed by shredding of
truck and passenger car tyres.
2
4
3
Editorial coordination: R&D Aliapur - Graphic Coordination: communication Aliapur - Design/production: Crayon Bleu - Photo credits:Aliapur DR, Michel Djaoui – March 2010
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Standards
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71, cours Albert Thomas - 69003 Lyon - FRANCE
Tel: +33 (0)4 37 91 43 20 - Fax: +33 (0)4 78 54 67 14
www.aliapur.fr - [email protected]
Used tyre recovery in France