Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Process of treating scrap or waste product containing solid...
Reexamination Certificate
2000-12-07
2002-05-21
Michl, Paul R. (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Process of treating scrap or waste product containing solid...
C241S023000, C241S065000
Reexamination Certificate
active
06391930
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a device and method for scrapping and destroying tires with metallic cords, using electric discharges. The device is designed to separate metal and rubber components for their subsequent separate salvage and retrieval, utilizing known, conventional techniques, such as melting the metal and forming rubber crumb for use in the production of flexible pavement and rubber articles, such as roofing, hydraulic insulating materials, heat-insulating and sound-insulating materials.
BACKGROUND OF THE INVENTION
Pneumatic vehicle tires that cannot be repaired or refurbished are a major source of the environmental pollutants and are, at the same time, however, a valuable source of recoverable and recyclable refuse. That is why the recovery of salvageable materials from such tires is a critical issue, especially in the more economically developed, and higher population density countries. Technological means for the solution of this problem must be adapted compatible basic conditions, such as ecological safety, economy and possibility of sufficiently complete salvaging of tires.
Typical tires manufactured today, having metallic cord reinforcements, usually referred to as “steel-belted” tires, have an outer tread surface that comes in contact with the road. The tread is made from rubber only. The tread is attached to two shoulders, one at either side of the tread strip. Each shoulder has a sidewall attached to it. Each sidewall terminates in a bead, which enables the tire to be mounted on and fit into an outer edge of a wheel. The tire has an inner carcass that is typically made from a corded textile material. The breaker is a bracing ply found below the tread. In steel-belted radial tires, the breaker typically includes two layers of metallic cord material. Each layer contains a plurality of separated metallic wires that are surrounded by rubber. The wires in adjacent layers are typically oriented at an angle of about ±70° with respect to a central geometric axis through the tire.
The simplest solution to the problem of the disposal of scrap tires, incineration, was widely used in many countries for many years. Up to 45% of worn-out tires in Germany and The Netherlands, and up to 40% of worn-out tires in Japan used to be incinerated (Tire Recycling Plant Tire Up, “Modern Tire Dealer”, 1987, No. 8, p. 6). However, incineration is accompanied by the formation of a complex of toxic substances, particularly sulfur-containing substances, the release of which into the atmosphere is an environmental hazard that far outweighs any benefits achieved in the recovery of residual metals and the recovery of heat generated by the incineration process.
Therefore, it is more preferable to utilize other technological means to provide for the destruction of worn-out tires and achieve the separation and recovery of useable rubber and metal by-products.
One alternative to incineration that is widely practiced is mechanical crushing. Devices for mechanically crushing tires, which operate at ambient temperature are known (“Gummibereitung”, 1987, Bd. 63, No. 10, p. 102-104). Other known devices are based on the deep freezing of the rubber component of the tires (Vorbildliches Recycling alter Reifen in Kall/Eitel, “Gummibereitung”, 1987, Bd. 63, No. 10, p 97-100). Both mechanical crushing and deep freezing processes are followed by the separation and recovery of components, however, the yields of useable materials are typically quite low.
Processes based on the mechanical shredding of resilient rubber from tires, together with the metallic cord content, followed by crushing of the shreds, are generally highly energy consuming and have low efficiency. Because of the low heat transfer coefficient of rubber, the size of tire shreds to be frozen in deep freezing processes is limited to particles that have a maximum dimension of not greater than 3 cm, which also leads to an increase in the specific energy consumption for shredding and mechanical crushing. Frozen pieces of rubber also do not result in homogeneous (in terms of size grading) semi-finished products. This also results in a certain portion of rubber being discharged together with the metal during magnetic separation.
It is also known that an electric-heat pre-treatment of tires reduces the loss of rubber and simplifies the separation of metallic cords.
In the simplest of devices utilizing this process (DE 2900655 Al), the device itself typically includes the following components:
first conveying means for delivering tires that have had their sidewalls removed to further processing equipment for complete destruction;
a tire destruction system in the form of a current source provided with contacts for connection to metallic cords, such that the source heats the cord wire and causes burning of the adjacent plies of rubber; and
second conveying means for transporting and discharging the by-products of tie destruction from the processing area.
Use of an electric-heat treatment based tire destruction process, over a prolonged period of time, is characterized, however, by one of the above-mentioned disadvantages of tire incineration, albeit to a lower degree, namely, with the discharge of toxic materials that pollute the atmosphere and are dangerous to workers and persons in general. In addition, processes requiring lengthy periods of heating are not efficient and have a high specific energy consumption. Moreover, the devices of such processes are effective only in processing those tires having metallic cords that thread through the breaker strip from one sidewall to the other, because only in such case, can substantially all cord wires be brought into secure electrical contact with a source of current, after the sidewalls have been cut off. Finally, the use of such a device creates a problem of separate salvaging of cut-off sidewalls.
Devices for heating the entire mass of metal inside the tires are known, and are provided, for example, in devices that utilize inductive heaters, such as are disclosed in German patent DE 3911082 A1 and European patent EP 0478774 A1. There are, however, a number of other disadvantages in the electric-heat destruction of tires that are more difficult to overcome.
Such other disadvantages can be overcome with the help of electric pulse destruction of tire cord wires. Such a process generally includes a step of passing short pulses of electric current of high density and power through the cord wires. This leads to heat emission, mainly at the boundaries of crystal grains of metal, and to the destruction of tire cord wires in a dangerous and potentially explosive manner.
One such device of this type is known in the art and is described in Russian patent RU 2050287. The device includes:
means for cutting off tire sidewalls (in one embodiment);
means for delivering tires for destruction;
a tire destruction system comprising:
a pulse-discharge unit based either on a capacitor bank or on an accumulative reactive LC-circuit, and
an axially symmetrical means for galvanic or electromagnetic connection of the pulse-discharge unit to a metallic cord made respectively either in the form of two current conducting members for fixing the tire to be destroyed mounted for relative reciprocating motion and having the working surfaces in the shape of truncated cones facing each other (by the smaller bases in particular) or in the form of the primary winding of a transformer that in any case must be coaxial with the tire to be destroyed and for this reason can be located either along the geometric axis of the tire or encompass the tire;
at least one means for discharging the products of the destruction from the working area and, preferably, protective chamber.
The tire destruction system based on the accumulative reactive LC-circuit and the means for electromagnetic connection of the pulse-discharge unit to a metallic cord in the form of the primary winding of a transformer seems to be preferential as far as it is serviceable for destroying the whole tires a priori. However, the exper
Bedjukh Aleksandr Radiyevich
Butko Valeri Grigoryevich
Parubochaya Tatyana Vasilyevna
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