WO1999059167A1

WO1999059167A1 - Process and apparatus for recycling jelly filled cable

Info

Publication number: WO1999059167A1
Application number: PCT/AU1999/000289
Authority: WO
Inventors: David Thomas Rowe
Original assignee: Individual
Current assignee: Individual
Priority date: 1998-05-07
Filing date: 1999-04-20
Publication date: 1999-11-18
Anticipated expiration: 2000-11-07
Also published as: EP1084499A1; TW434582B; CA2331346A1

Abstract

A process for recycling jelly filled cable places the cable in a receptacle (14). Air is recirculated by a fan (2) through ducting (18) into the receptacle (14) through a false base (19) out of the receptacle (14) through a hood (11) and ducting (16, 3) past a heater and back to the fan (2). On the resulting heating of the cable to a temperature in excess of 115 °C, the jelly is absorbed by the polyethylene coating of the cable.

Description

1 Title of Invention:

Process and Apparatus for Recycling Jelly Filled Cable.

Technical Field: This invention relates to the recycling of metal strands from cable, particularly telecommunications cable.

Background Art:

The recycling of telecommunications cable to recover copper strands has traditionally been carried out by cutting the cable into very small pieces, then separating the plastic and copper components by specific gravity. For this process to work effectively, the cable needs to be free from grease, wax, jelly, or other sticky substances, to allow the plastic and copper components to easily separate from each other.

Telecommunications cables are usually made up of internal copper strands surrounded by a polyethylene coating. During manufacture, some telecommunications cables are pumped full of wax or 'jelly', in order to counter problems caused by the ingress of water into telecommunications cable once in use.

Problems have been encountered with the recycling of jelly filled cable so as to recover copper, usually in a granulated form, clean, dry and free from any stickiness or jelly residue.

Attempts have been made to find a way of effectively processing this jelly cable but to date no known process has been able to recover totally clean copper without specifically treating the end copper product with solvents in order to remove the jelly residue. Known processes separate the jelly and plastic residue from the copper by using as a fluid separating mechanism either hot water, hot water and detergent, or a combination of hot water, detergents and/or solvents. These treatments still leave the recovered copper granules feeling 'sticky' to the touch, with a tendency to clump together, unlike the clean and dry copper granules obtained recycling cable free of jelly » 2 In addition, with these processes using detergents and/or solvents, additional costs are incurred in the purchase of these solvents, and also in disposing of them in an environmentally acceptable manner. Further, there is, in some processes, a loss of a percentage of the copper granules which remain adhered to the sticky plastic/jelly waste. It is not possible to recover any of this lost copper without expenditure disproportionate to the value of the copper.

Furthermore, it is necessary to establish a separate dedicated plant, to avoid having any jelly residue contaminating the machinery used for processing non-jelly filled cable. This has limited the number of recyclers capable of processing jelly cable on a worldwide scale.

This invention accordingly provides a process of recycling jelly filled cable by providing a pretreatment step in order to recover copper free or substantially free of jelly residue and which avoids the use of hazardous solvents or burning. Although the invention is described in relation to the recovery of copper, it has application to the recovery of any metal from jelly filled cables.

Summary of the Invention: In one form the invention resides in a process for recycling metal from polyethylene coated jelly filled cable, including heating the cable to a temperature in excess of 115°C so as to cause the jelly to be absorbed by the polyethylene coating.

In another form the invention resides in apparatus for recycling metal from polyethylene coated jelly filled cable, including a receptacle for holding cable during the process, and a heater for heating a medium to a temperature in excess of 115°C.

Preferred Aspects of the Invention:

Preferably the apparatus further includes means for recirculating the medium from the heater into the receptacle and back to the heater.

Preferably the medium is air. An alternative preferred form of the medium is water. 3

Where the medium is water, it is preferred that the process include the step of chopping or shredding the cable into segments before heating.

Preferably, the cable is bathed in the medium while it is being heated.

Preferably, the metal is copper.

Preferably, the cable is heated to a temperature between 115°- 135°.

It is particularly preferred that the cable be heated to a temperature of 125°C.

Preferably, the cable treated according to the above process is free or substantially free of any jelly residue and can be treated by conventional known methods in order to recover copper free or substantially free from j elly residue.

Brief Description of the Drawings:

Figure 1 is a perspective view of apparatus according to an embodiment of the present invention.

Figure 2 is an elevational view, partly in section, of the apparatus of Figure 1.

Figure 3 is a cross-sectional view along the line 3-3 of Figure 2.

In order that the invention may be more readily understood, preferred embodiments of it will now be described with reference to the drawing.

Description of the Preferred Embodiments:

Apparatus 1 according to one embodiment of the present invention includes a high temperature, high pressure 'furnace' fan 2 connected to ducting 3 which contains a heater (not illustrated). The heater may be powered by any suitable source, such as natural gas or electricity 4

The fan 2 and ducting 3 are fixedly mounted on a base 4. Support members 6 and 7 project upwardly from base 6, and are braced by diagonal members 8 and 9.

The upright members 6 and 7 the diagonal members 8 and 9 and the base 4 define a bay for the reception of a removable receptacle 14 to hold cable (not illustrated) which is being treated in accordance with the process. Preferably, the receptacle 14 is double- skinned and contains thermal insulation (not illustrated) between the skins.

There is an opening 20 in the side wall of receptacle 14. Ducting 18 communicates between the outlet of the fan 2 and opening 20 in receptacle 14. The receptacle 14 has a 'false bottom' in the form of a fabricated metal grid 19. The base of the receptacle 14 includes a trough shaped region 17. An outlet 21 in the lower rear centre of the receptacle 14 communicates with the interior of the trough and is closed off by a tap (not illustrated) exterior to the trough 17.

A hood 11 is pivotally mounted near the uppermost ends of support members 6 and 7. Preferably, the hood is double-skinned and contains thermal insulation (not illustrated) between the skins. It is preferred that the hood 11 be pivotable between the lower position illustrated in the drawings and the upper position shown in outline in Figure 2 by operation of the hydraulic cylinders 12 and 13.

Flexible ducting 16 communicates between the hood 11 and the ducting 3, which in turn communicates with the inlet of the Fan 2.

When the apparatus is in use, the hood 11 is in the lower position illustrated in the Figures to form a substantially airtight seal with the opening of the receptacle 14. The receptacle 14 is positioned so that a substantially airtight seal is formed between opening 20 and the ducting 18. Airflow induced by the fan 2 is through ducting 18, upwards through the false bottom 19 of receptacle 14, out of the receptacle 14 through flexible ducting 16 into ducting 3 where it flows past the heater (not illustrated) and is heated, and into the inlet of the fan 2. 5

According to the process of the present embodiment, telecommunications cable made up of copper strands having a polyethylene coating and filled with a wax or jelly is then placed in the receptacle 14 where it is exposed to super heated medium and heated to a temperature of 125°C.

At approximately 115°C the jelly will start to be absorbed by the polyethylene coating of the cable. Heating the cable up to 125°C will result in all or substantially all of the jelly being absorbed.

As the cable is heated, but before the cable reaches a temperature where the jelly is absorbed, the jelly expands. As the jelly expands, some jelly is extruded out of the cable ends. This extruded jelly drips through the false bottom 19 of the receptacle 14 and accumulates in the trough 17. Once the absorption process is complete, but before cable is tipped out of the receptacle, jelly which has accumulated in trough 17 may be drawn off through the tap (not illustrated) which is attached to outlet 21.

The absorption of the jelly will take place above 125°C. However, at approximately 135°C and above the polyethylene coating will start to melt into a solid mass. Elevating the temperature further will, depending on how high the temperature is raised, cause the plastic to melt to a liquid state. At this point the plastic will also drip through the false bottom 19 and accumulate, like the liquid jelly, in the trough area 17. The amount of plastic that so melts off will depend on the level to which the temperature is elevated.

After heat treatment, the cable is then subjected to further treatment by conventional means to remove the copper wire from the polyethylene coating. The copper recovered from this process is or is substantially dry and free from jelly residue or 'stickiness'.

Claims

6 Claims

1. Apparatus for recycling metal from polyethylene coated jelly filled cable, including a receptacle for holding cable during the process, and a heater which is adapted to heat the medium to a temperature in excess of 115°C.

2. Apparatus as claimed in claim 1, further including means for recirculating the medium from the heater into the receptacle and back to the heater.

3. Apparatus as claimed in claim 1 or claim 2, wherein the medium is air.

4. Apparatus as claimed in claim 3, further comprising a fan for circulating air from the heater through the receptacle and back to the fan.

5. Apparatus as claimed in claim 3 or claim 4, wherein the receptacle is open-topped and includes: side walls which define the open top; a bottom; and a false bottom which is located above the bottom to allow both the drainage of jelly and the flow of air through the false bottom.

6. Apparatus as claimed in claim 5 wherein the receptacle further includes an opening in a side wall intermediate the false bottom and the bottom.

7. Apparatus as claimed in claim 5 or claim 6 wherein the bottom of the receptacle includes a trough to allow the accumulation of jelly.

8. Apparatus as claimed in any one of claims 3 to 7, wherein the apparatus further comprises a base to which the fan and heater are fixedly mounted and on which the receptacle is removably mountable.

9. Apparatus as claimed in any one of claims 3 to 8, wherein the apparatus further includes a hood which is pivotally mounted to move between an open position and 7 a closed position in which it may form a substantially airtight seal with the top of the receptacle.

10. Apparatus as claimed in claim 9 which further includes a frame which is fixedly mounted on the base and in which the hood is pivotally mounted on the frame.

11. Apparatus as claimed in claim 1 or claim 2, wherein the medium is water.

12. Apparatus as claimed in any one of the preceding claims, wherein the heater is adapted to heat the medium and thus the cable to a temperature between 115°-

135°.

13. Apparatus as claimed in claim 12, wherein the heater is adapted to heat the medium and thus the cable to a temperature of 125°C.

14. Apparatus as claimed in any one of the preceding claims, substantially as described with reference to the drawings.

15. Apparatus substantially as described with reference to the drawings.

16. A process for recycling metal from polyethylene coated jelly filled cable, including heating the cable to a temperature in excess of 115°C so as to cause the jelly to be absorbed by the polyethylene coating.

17. A process as claimed in claim 16, wherein the cable is heated in a medium.

18. A process as claimed in claim 17, wherein the medium is recirculated from the heater into the receptacle and back to the heater.

19. A process as claimed in claim claim 17 or claim 18, wherein the medium is air.

20. A process as claimed in claim 17 or claim 18, wherein the medium is water. 8

21. A process as claimed in claim 20, further including the step of chopping the cable into segments before heating.

22. A process as claimed in claim 20, further including the step of shredding the cable into segments before heating.

23. A process as claimed in any one of claims 16 to 22, wherein the cable is heated to a temperature between 115°-135°.

24. A process as claimed in claim 23, wherein the cable is heated to a temperature of 125°C.

25. A process as claimed in any one of claims 16 to 24, wherein the heating of the cable continues until the cable is substantially free of any jelly residue.

26. A process as claimed in any one of claims 16 to 25 wherein the metal is copper.

27. A process as claimed in any one of claims 16 to 26, substantially as described with reference to the drawings.

28. A process substantially as described with reference to the drawings.