TOM 5 styczeń - luty 2001 r. Sta& tM M W f' nr 1
Alexander Bedjukh*, Hares Youssef **
Recycling of post-consumer tires with metallic cord by magnetic shock method***
This presentation considers experim ental results o f m etal and rubber separation inside post-consum er tires by m agnetic shock m ethod and some calculations o f commercial tire recycling with the method. An electric pulses installation with energy less than 9 kJ and only 2% efficiency had realized m etal separation in sam ples fro m tire with sizes about 20x4 cm 2. Energy consum ed at the separation is less than 0.01 kWh p e r 1 kg o f tire weight.
Full recycling technology includes fu rth e r m echanical crushing and m odification o f rubber crumb. A s the result one can have the material suitable fo r the vulcanization directly into rubber goods. Such param eters o f commercial recycling as estim ated cost and cost o f l ton o f the m odified rubber crumbs are given.
Key words: post-consum er tire recycling, tires with metallic cord, magnetic shock m ethod
Recykling zużytych opon z kordem stalo
wym metodą wstrząsu magnetycznego
Kom unikat obejmuje wyniki badań oddzielania metalu od gumy wewnątrz zużytych opon m etodą w strząsów m agnetycznych oraz obliczania kosztów recyklingu opon przeprow adzonego tą metodą w skali technicznej.
W przypadku oddzielania metalu z wycinka opony o wymiarach 20x4 cm2 wystarczy pulsacja elektryczna o energii mniejszej niż 9 kJ i wydajności zaledwie 2%. Zużycie energii na oddzielenie metalu je s t mniejsze niż 0,01 kWh na 1 kg masy opony.
Technologia recyklingu obejm uje dalsze rozdrabnianie m ech a n iczne i m odyfikację zm ielonej gumy. W wyniku całego procesu uzyskuje się m ateriał odpowiedni do form ow ania i wulkanizacji wyrobów gumowych.
P odano p a ra m e try ekonom iczne pro cesu recyklingu, takie ja k koszty i cenę 1 tony miału gumowego.
Słowa kluczowe: recykling zużytych opon, opony z kordem stalowym, m etoda wstrząsu magnetycznego
* Taras Shevchenko University, Kyiv
** Hares Youssef Handels Ges.m.b.H.
*** Paper presented at International Conference Elastomery’2000, 14-15.11.2000, Warsaw
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Sfa& toH H & itt nr 1 styczeń - luty 2001 r. TOM 5
1. Introduction
Since the using of tires reinforced by metallic wi
res, utilization of these tires with a purpose of reusing its raw materials is remained a difficult problem.
The direct mechanical crushing of tires with me
tallic cord is characterized by high amortization of equ
ipment and high-energy consumption (up to 1.5 kWh per 1 kg of rubber crumb). The resulting crumb has got a few metallic inclusions (0. 0 1 % - 0.1 %).
The cryogenic m ethod perm its to obtain rubber crumb w ithout the m etallic inclusions. However, the crumb lost its elasticity and the energy consum ption is higher (up to 2.5 kW h per 1 kg of rubber crumb).
Others m ethods one could use such as the m i
crowave heating of m etal or different explosive m e
thods still didn’t give satisfactory results.
In this work we examine a new magnetic shock method of metal separation inside a tire. We also present some calculated results of commercial tire recycling.
2. Experimental results
A high-voltage (up to 4 kV) electric pulse instal
lation had been devised for creating electric dischar
ges with energy about 9 kJ (less than 0.003 kWh). A period of electric fading oscillations was about 200 ms.
Experim ental study of the metal separation has been realized in the follow ing way. A sample cut out from a tread part of car tire (sizes about 20x4 cm 2) was placed in special means. The means had got two conducting fixing members that connected all cord wire ends from one layer of m etallic cord to the installa
tio n’s high-voltage outlets. One of the members had got a long conductive protrusion and all cord wires of the sample had been arranged parallel to the protru
sion.
A high-voltage electric pulse had gated in oppo
site directions through the cord wires and said protru
sion that causes a m agnetic shock betw een the wires and th e p r o tr u
sio n . T h e tre a d rubber part of the sample had been f a s te n e d to th e means. As the re
sult we had got a separating of the
wires and the rubber in the sample.
The cord wires separated from adjoining rubber have got yellow color. W hich means a thin film of brass is rem ained around cord wires. So, the separation has been done very clean.
Under the action of electric pulse the cord wires had got heating. The average tem perature of the wires was raised to 500°C but the rubber has got heating to 35-40°C only.
In the experim ents we have done a ratio between electric pulse energies consumed to the magnetic shock and to the metal heating had been equal about 1/50.
This is only 2% efficiency of the installation. Despite this, the metal separation has been realized in the sam
ples in size of about 1/30 of a car tire. So, the energy consum ption to m etal separation by m agnetic shock is less than 0.01 kW per 1 kg of a tire weight even in our experiments.
A devise realized the m agnetic shock for a full tire is described in [1].
3. Recycling method
According to the recycling method a tire’s rub
ber released from m etallic cord is crushed in crumb by usual m echanical equipm ent.
The energy consum ed in the crushing is about 0.3-0.5 kW per 1 kg of the crumb. That is in 2-3 times less than one would use a usual mechanical equipment, because, in this case, the energy is consumed both to crushing metal and rubber together and to their addi
tional separation.
A fter crushing the crum b can be m odified in a special apparatus. The modification is realized at room tem perature and m odified additions are present. As the result one could have got a raw material fitting to vulca
nizatio n in rubb er goods directly. The energy c o n sum ed on this is less than 0.02 kW h per 1 kg of m odified crum b.
Let us give the tire-recy clin g diagram in F i
gure 1.
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TOM 5 styczeń - luty 2001 r. S ’bzA&MKe'Uf nr 1
As com pared to others m ethods, our one has the following advantages:
■ Energy consum ption is low er in 2 ... 3 times;
■ Waste material is practically absent (mechanical or cryogenic technologies give now about 30% of waste);
■ Obtained rubber crum b is of higher quality, becau
se it does not lost its elasticity as with cryogenic processing, and it has not metal inclusions as with mechanical crushing;
■ The m odification of crum b perm its us to obtain the raw m aterial one could use instead a primary rub
ber in m ost of rubber goods.
This recycling m ethod is an appropriate techno
logy due to absence of large rubber heating or cooling.
4. Calculated results of the com
mercial recycling
The commercial realization of tire recycling con
sists of three stages. These are a pilot electric-pulse installation, a pilot factory for car tire recycling and than a factory for truck tire recycling. The first stage, a pilot electric-pulse installation, would be needed for a testing of recycling method, a training of electric-pul
se equipm ent and an optim ization of the metal separa
tion process. This stage duration will be about six months. The second stage (about nine m onths of dura
tion), a pilot factory of car tire recycling, would help us to test and control the recycling process in general.
At last, the third stage, a creation of the truck tire-re
Table 1. Estim ated cost
cycling factory, will complete the realization of the first pilot recycling factory and will last nine months.
Let us represent the estim ated cost for creating the first pilot-recycling factory.
The first production line (car tire recycling) will start after 15 months of the project duration. The fac
tory output will be about 300 kg of m odified rubber crumb per hour (or about 100 tons per month) during next 9 months. A fter 24 months from the project dura
tion the factory output will be increased up to 600 tons of m odified rubber crumb per month.
Let us give a calculated cost of 1 ton of the m o
dified rubber crumb:
Salary was calculated in the following way:
An average salary of an employee will be $ 1500 per m onth. The staff w ill include about 10 persons.
The factory output w ill be about 600 tons o f a m o
dified rubber crum b per m onth. So, a part o f w ages in crum b’s cost will be equal to $1500x 10/600=$25.
Equipment depreciation was calculated in the following way:
20% of annual equipm ent depreciatio n w ill be about $650000/5=$ 130000. The annual output is equal to 6000 tons o f crum b. So, a part o f expense for equipm ent depreciation in cru m b ’s cost w ill be equal to $ 1 30000/6000~$25.
Production costs (including electrical energy) was calculated in the following way:
Energy consum ption is calculated in such way:
$0.05 (it is a price of 1 kW h)x400 (it is the energy consumption of 1 ton crumb produced) = $20. Let other costs (heating, illumination, transport and so on) are equal $ 10. So, in total, production cost will be added up to $20+$ 10= $30.
N°
Cost estimate (in thousands of US
dollars)
First stage, the electric-pulse
installation
Second stage, the pilot factory for car
tires
Third stage, the pilot factory for
truck tires
Total
1 Wages 25 60 60 145
2 Charge extra wages 12.5 30 30 72.5
3 Equipment
■ electric pulse - 50 250 300
■ mechanical - 120 100 220
■ for modification - 80 50 130
4 Materials 24 40 30 94
5 Other direct costs 2 4 3 9
6 Travel 4 6 7 17
7 Subcontracts - 100 60 160
8 Overhead 7.5 40 60 107.5
9 Estimated total cost 75 530 650 1255
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SfaatO iH & U f, nr 1 styczeń - luty 2001 r. TOM 5
All parts of calculated cost is given in Table 2.
Table 2. Calculated cost o f 1 ton o f the m odified rub
ber crumbs
N° Component parts of the cost (in US
dollars)
1 Wages 25
2 Charge extra wages (40% from wages) 10
3 Equipment depreciation 25
4 Production costs (including electrical energy) 30
5 Cost 90
6 Total taxes 20
7 Total cost 110
The m odified rubber crum b could replace a pri
mary rubber. M arket price of the rubber is now about
$1000-2000 per 1 ton. One could sell the modified rub
ber crumb at the price of $300-400 per 1 ton. In this case the selling profit will be large enough to increase the es
timated cost for 1 year of the factory’s work.
5. Conclusion
The magnetic shock m ethod of tire recycling will be able to solve the problem of tire recycling cost- efficiently and with ecological safety.
Due to com plete separation of metal is realized:
■ the energy consum ption is m aterially reduced (less than. 0.5 kW h per 1 kg of the crumb);
■ the equipm ent depreciation is reduced;
■ the rubber crum b will be m uch better and cheaper than present rubber crumb.
References
1. A. Bedjukh, T Parubochya, V Butko. „Devise fo r de
stroying tires with metal cord using electric discharges ”.
International claim fo r invention rights. Number o f in
ternational publication is WO 99/51412from 14.09.1999
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