Particle size distribution - Aliapur · Particle size distribution Definition A set of geometric characteristics that define the state of a divided solid. Expression of the distribution

Particle size distribution

Particle size distribution is an essential measurement for the industrialists that

produce and use granulates.The particle size distribution methods applied to end-of-life tyre granulates

(ELT) require certain precautions if the measurements produced are to be both

reliable and reproducible.Aliapur’s Research & Development

department has focused on designing, testing and validating a process

for determining particle size distribution for this type of product.

This process was used as the basis for the AFNOR standard published in

February 2007.

Particle size distribution

Definition

A set of geometric characteristics that define the state of a divided solid. Expression of the distribution of a material that has been fragmented between the different particle size categories of which it is composed.

Particle size distribution is the measurement of the size of the granulates contained in a batch of material and their distribution in relation to size. Sieving is a particle size distribution method.

Application to granulates obtained from ELT

End-of-Life Tyre (ELT) granulates are obtained by means of a variety of processes for grinding rough shedded tyre. Their size generally ranges between 0.8 and 20 mm in the different productions observed. The size depends on the process used by the granulaters.

By means of successive sieving, the main produ-cers produce at least three main types of granulate: from 0.5 to 2.5 mm, to be used for example as the under-layer in synthetic turf; from 1 to 4 mm, particu-larly used in the shock-absorbing under-layer in play

areas and industrial surfaces; and from 2 to 8 mm to be used, for example, in the composition of eques-trian floors or athletics tracks. Certain industrialists also produce “powder”, sized between 0 and 1 mm. This latter category can be used to produce moulded objects.

RemarkToday, thanks to the studies carried out by Aliapur, it has been possible to specify the categories “powder”, “granulate” and “shred”.

Shred

Sorting of the granulates by means of sieving

n Powder: batches of tyre particles the size of which is comprised between 0 and 0.8 mm, with no textile fibres or wire.

n Granulates: batches of tyre particles the size of which is comprised between 0.8 and 20 mm, with no textile fibres or wire.

All batches of tyre particles of more than 20 mm in size are commonly called “shred”. They generally contain textile fibres and wire.

Method

On the basis of existing standards in the fields of mineral granulates, agricultural granules and cork granulates, the laboratories and experts in the ELT-Afnor standardization commission have tested a range of different sifters and sieves, as well as the optimum quantity of granulates to be processed in a single operation. The results of their studies have shown that the most robust and most reliable method consists in using the following operating method.

SANDdensity = 2

GRANULATESdensity = 0,4

How can you guarantee the reproducibility of the measurements of a product that is less well-suited to sieving (low density, elasticity)?

Operating mode

n Weigh the mass of the laboratory sample: 500 g.

n Set up the nest of test sieves on the beater bar (see photo): 6 x 400 mm diameter sieves of different mesh sizes depending on the product to be obtained.

n Lift the cover and put the laboratory sample in the upper sieve in the nest.

n Put the cover back into position and turn the beater bar on for 5 minutes (frequency of 15 Hz).

n Recover the material from the recipients and clean each side of the sieves (top and bottom) with large and/or small brushes, and include any residue with each corresponding particle size category.

n Then weigh on the scales the quantities of granulates held in each sieve and the quantity recovered from the bottom.

This operating mode was used to establish a standard in February 2007: Afnor XP T47-752. This standard specifies the type and number of sieves to be used and defines how to put the products into categories. It is cited as a reference standard in the standard project, “PR NF P90-112 – Sols sportifs – Terrains de grands jeux en gazon synthétique – Conditions de réalisation”.

Method recommended and studied by Aliapur

Results

n d is the size of the mesh of the smallest sieve allowing between 1 and 10 % of the granulates (in mass in relation to total mass) to pass through. For example, if a sieve with a mesh size of 0.08 mm lets less than 1 % of the granulates through, d will then be equal to the mesh size of the next sieve up that let between 1 and 10 % of the granulates through.

n D is the size of the mesh of the largest sieve allowing between 90 and 99 % of the granulates (in mass in relation to total mass) to pass through.

Defining the d/D ratioThis ratio makes it possible to quantify the particle size of a sample.

Typologies of products analysed

The table below identifies the types of products analysed in the various factories.

Factory 1 Factory 2 Factory 3 Factory 4

Powder <0.8 mm

Granulates 0.5-2 mm

Granulates 1-4 mm

Granulates 1-6 mm

Remarks

If one or both of these values cannot be determined, it is necessary to redo the measurement using better adap-ted sieves.

Determining d and D is only valid if at least 2 sieves different from these values are situated between these same values.

Cases of common applications

The most common applications: moulded objects, asphalt rubber…Granularity in accordance with standard XP T47-752Sieves used: 0.08 – 0.125 – 0.2 – 0.315 – 0.5 – 0.63 mm

Sieve 0.5 mm

Sieve 1 mm

Sieve 1.25 mm

Sieve 1.4 mm

Sieve 1.6 mm

Sieve 2 mm

0

20%

40%

60%

80%

100%

0

20%

40%

60%

80%

100%

0

20%

40%

60%

80%

100%

SIEVING

SIEVING

SIEVINGE

Factory 1 - d/D = 0.5/2 Factory 3 - d/D = 0.5/1.6 Factory 4 - d/D = 0.5/1.25Fa F FF

Applications la plus courante : gazons synthétiquesselon norme XP T47-752

Factory 1 - d/D = 1.6/5 Factory 3 - d/D = 0.5/4 Factory 4 - d/D = 1.6/5Fa F FF

Applications les plus courantes : aires de jeux, tapis amortissants, sols industriels, pièces moulées…

selon norme XP T47-752

Sieve0.5 mm

Sieve 1.6 mm

Sieve 2 mm

Sieve 3.15 mm

Sieve 4 mm

Sieve 5 mm

Sieve 0.08 mm

Sieve0.125 mm

Sieve 0.2 mm

Sieve 0.315 mm

Sieve 0.5 mm

Sieve 0.63 mm

Factory 3 - d/D = 0.2/0.5 Factory 4 - d/D = 0.2/0.63F FF

Applications les plus courantes : pièces moulées,asphalte rubber, etc.


Sieve 0.5 mm

Sieve 1 mm

Sieve 1.25 mm

Sieve 1.4 mm

Sieve 1.6 mm

Sieve 2 mm

0

20%

40%

60%

80%

100%

0

20%

40%

60%

80%

100%

0

20%

40%

60%

80%

100%

SIEVING

SIEVING

SIEVINGE






Sieve0.5 mm

Sieve 1.6 mm

Sieve 2 mm

Sieve 3.15 mm

Sieve 4 mm

Sieve 5 mm

Sieve 0.08 mm

Sieve0.125 mm

Sieve 0.2 mm

Sieve 0.315 mm

Sieve 0.5 mm

Sieve 0.63 mm




Most common application: synthetic turfGranularity in accordance with standard XP T47-752Sieves used: 0.5 – 1 – 1.25 – 1.4 – 1.6 – 2 mm

Sieve 0.5 mm

Sieve 1 mm

Sieve 1.25 mm

Sieve 1.4 mm

Sieve 1.6 mm

Sieve 2 mm

0

20%

40%

60%

80%

100%

0

20%

40%

60%

80%

100%

0

20%

40%

60%

80%

100%

SIEVING

SIEVING

SIEVINGE






Sieve0.5 mm

Sieve 1.6 mm

Sieve 2 mm

Sieve 3.15 mm

Sieve 4 mm

Sieve 5 mm

Sieve 0.08 mm

Sieve0.125 mm

Sieve 0.2 mm

Sieve 0.315 mm

Sieve 0.5 mm

Sieve 0.63 mm




Sieve 0.5 mm

Sieve 1 mm

Sieve 1.25 mm

Sieve 1.4 mm

Sieve 1.6 mm

Sieve 2 mm

0

20%

40%

60%

80%

100%

0

20%

40%

60%

80%

100%

0

20%

40%

60%

80%

100%

SIEVING

SIEVING

SIEVINGE






Sieve0.5 mm

Sieve 1.6 mm

Sieve 2 mm

Sieve 3.15 mm

Sieve 4 mm

Sieve 5 mm

Sieve 0.08 mm

Sieve0.125 mm

Sieve 0.2 mm

Sieve 0.315 mm

Sieve 0.5 mm

Sieve 0.63 mm




Most common application: play areas, shock-absorber mats, industrial floors, moulded objects…Granularity in accordance with standard XP T47-752Sieves used: 0.5 – 1.6 – 2 – 3.15 – 4 – 5 – 6.3 mm

Sieve 0.5 mm

Sieve 1 mm

Sieve 1.25 mm

Sieve 1.4 mm

Sieve 1.6 mm

Sieve 2 mm

0

20%

40%

60%

80%

100%

0

20%

40%

60%

80%

100%

0

20%

40%

60%

80%

100%

SIEVING

SIEVING

SIEVINGE






Sieve0.5 mm

Sieve 1.6 mm

Sieve 2 mm

Sieve 3.15 mm

Sieve 4 mm

Sieve 5 mm

Sieve 0.08 mm

Sieve0.125 mm

Sieve 0.2 mm

Sieve 0.315 mm

Sieve 0.5 mm

Sieve 0.63 mm




Sieve 0.5 mm

Sieve 1 mm

Sieve 1.25 mm

Sieve 1.4 mm

Sieve 1.6 mm

Sieve 2 mm

0

20%

40%

60%

80%

100%

0

20%

40%

60%

80%

100%

0

20%

40%

60%

80%

100%

SIEVING

SIEVING

SIEVINGE






Sieve0.5 mm

Sieve 1.6 mm

Sieve 2 mm

Sieve 3.15 mm

Sieve 4 mm

Sieve 5 mm

Sieve 0.08 mm

Sieve0.125 mm

Sieve 0.2 mm

Sieve 0.315 mm

Sieve 0.5 mm

Sieve 0.63 mm




*Powder: granulates of less than 0.8 mm.

Interview with a user“With ELT granulates, we have the same requirements as for a manufactured product.”

Didier Miranda, General Director of Eurofield.“We manufacture and market synthetic turf, essentially for sports grounds. ELT granulates are used in the composition of turf for so-called “big games” grounds such as football or rugby, where the surface area can be up to 8,000 m². These granulates provide all the sports qualities needed for our product and play a part in ensuring that the turf interacts well with the athletes. Shock-absorbing, flexibility and energy restitution are some of the qualities we are looking for.

For us, particle size distribution is essential. The granulates must be of a precise particle-size distribution, as well as being reliable and stable, as this raw material is part of the standardization process for our products, as well as for the simple reason that the

appropriate particle size guarantees performance! With ELT granulates, we have the same requirements as for a manufactured product. Not all granulators have fully understood that they must increase appreciation of granulates by being more sensitive to the requirements of the users. If I order 0.5-1.5 mm, I don’t want 0-25 mm. Powder* in particular will pose a problem throughout the lifetime of our product, from installation to use. But particle size is not the only characteristic that is important for us: morphology is just as important. Aliapur plays a part in raising the awareness of the various key players in the sector with regard to the importance of quality, establishing standards, etc. This approach is clearly starting to pay off, but it remains a long-term project.”

Eurofield S65ML2

ConclusionIn the face of the new regulatory context and what is at stake in the field of sustainable development, the recycling sector for used tyres must harmonise and codify its practices in order to develop and extend to an optimum level.

As particle size distribution is one of the most important parameters, Aliapur has aimed to provide its expertise to the task of establishing the common references essential for everyone to work together.

This method, if all the key players adopt it, will make it possible to optimize the use of granulates for certain applications and, amongst other things, control the adjustment parameters for a grinding process.

References

Standardsn Afnor XP T47-752 – February 2007End-of-Life Tyres (ELT) – Determination of the particle size analysis of granulates issued from End-of-Life Tyres – Method based on the mechanical sieving of product.

n ASTM D5644-96 – August 2000Standard Test Method for Rubber Compounding Materials – Determination of Particle Size Distribution of Recycled Vulcanizate Particulate Rubber

n ISO 2030 – November 1990Crude cork granules – Particle size distribution analy-sis using mechanical sieving.

n NF EN 933-1 – December 1997Tests for determining the geometric characteristics of granulates – Part 1: determining granularity. Particle size distribution analysis by sieving.

Reference studies

n "Analyses de granulats, de fibres textiles et de fibres métalliques issus du broyage de PUNR véhi-cules légers (VL) et poids lourds (PL) – LRCCP pour le compte d’Aliapur – Juin 2005".

n "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 compa-raison de différents procédés de granulation – BRGM pour le compte d’Aliapur – Février 2007".

ALIAPUR - Research & Development71, cours Albert Thomas - 69003 Lyon - FRANCETel: +33 (0)4 37 91 43 20 - Fax: +33 (0)4 78 54 67 14www.aliapur.fr - [email protected]

USED TYRE RECOVERY IN FRANCE

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Sample sitesThe studies carried out by Aliapur were based on 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 Factory 1: successive shredding of truck tyres.

n Factory 2: successive shredding of passenger car tyres.

n Factory 3: shredding by crushing of truck and passenger car tyres.

n Factory 4: cryogenics followed by shredding of truck and passenger car tyres.

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Particle size distribution - Aliapur · Particle size distribution Definition A set of geometric characteristics that define the state of a divided solid. Expression of the distribution