GB2348428A

GB2348428A - Reclaiming thin film plastics waste

Info

Publication number: GB2348428A
Application number: GB9907566A
Authority: GB
Inventors: George Louis Bridge
Original assignee: PLASALLOY Ltd
Current assignee: PLASALLOY Ltd
Priority date: 1999-04-01
Filing date: 1999-04-01
Publication date: 2000-10-04
Also published as: GB9907566D0

Abstract

Thin film plastics waste is reclaimed by spraying the waste with oil at elevated temperature through nozzles (18). The effect is to densify and make rigid the waste into lump form for ease of further processing. The mixture of waste and oil collects in a coalescence chamber (11) from which the waste, in lump form, is removed by conveyor (17) for further processing. Preferably, the temperature of the oil on leaving the nozzles (18) is approximately 150{C.

Description

Reclaiminq thin film plastics waste This invention relates to a process for reclaiming thin film plastics waste.

Generally, re-processing of thin film plastics waste in the form of bags, rolls of film and loose sheets, is effected by means of granulators. However, because of their irregular shape and configuration, the waste products often do not feed into the re-processing equipment and, in consequence, there is a break-down in the process.

According to the present invention, there is provided a process for reclaiming thin film plastics waste including subjecting the waste to oil at elevated temperature so as to effect coalescence of the waste and thereby densify and make rigid the waste into lump form for further processing.

Following is a description, by way of example only and with reference to the accompanying drawing, of one method of carrying the invention into effect.

The drawing is a diagrammatic representation of apparatus for carrying out the process, the apparatus comprising, in series, a weir chamber 10, a coalescence chamber 11 and a drain chamber 12.

The weir chamber 10 is separated from the coalescence chamber 11 by means of a weir wall 13, which is of smaller vertical dimension than external walls of the weir chamber 10, one of which external walls 14 is provided with an inlet 15. The weir chamber 10 contains a lower portion of a conveyor 16, an upper end portion of which extends outwardly of the external wall 14.

The coalescence chamber 11 also contains a lower portion of a conveyor 17, an upper portion of which extends over the drain chamber 12, and a plurality of overhead spray nozzles 18. The coalescence chamber 11 is provided with two outlets 19,20 one of the outlets 19 being connected to the inlet 15 by means of a conduit 21 including, in series, a valve 22, a pump 23 and a heat exchanger 24 and the other of the outlets 20 being connected to the nozzles 18 by means of a conduit 25 including, in series, a valve 26, a pump 27 and a heat exchanger 28.

The drain chamber 12 includes a pair of cooperating rollers 29 located adjacent an upper end portion of the conveyor 17 extending from the coalescence chamber 11 and a delivery conveyor 30 a lower end portion of which is located below the rollers 29.

An in-feed conveyor 31 is provided for supplying plastic waste to the weir chamber 10.

In operation, oil at a temperature of 80 C-90 C is supplied from the heat exchanger 24 to the weir chamber 10 via the inlet 15 and oil at a temperature of 150 C is supplied to the nozzles 18 of the coalescence chamber 11.

Waste is deposited into the weir chamber 10 by means of the in-feed conveyor 31. The waste is contacted in the weir chamber 10 by the hot coalescing oil therein which separates the light plastic material from any heavy contaminants, such as metal objects. The flow of hot coalescing oil conveys the plastic waste over the weir wall 13 and into the coalescing chamber 11. Heavy material which was separated from the plastic waste in the weir chamber 10 is removed by the abstraction conveyor 16 and discarded.

The coalescing chamber 11 comprises a high temperature zone in which the carried forward plastic is heat coalesced by hot coalescing oil spray directed form the nozzles 18. The effect of the coalescence is to densify and make rigid the plastic into irregular lump form. This form is suitable for downstream processing in conventional re-processing equipment, for example granulators.

The coalesced plastic in the coalescing chamber 11 is conveyed forward through the oil contained in the chamber 11 by the forwarding conveyor 17. The coalesced plastic passes between the rollers 29 where it is de-oiled and falls onto the delivery conveyor 30 for delivery to the next processing stage. The coalescing oil is recirculated via the heat exchangers 24,28 such that the temperature for coalescence is maintained.

Claims

Claims 1. A process for reclaiming thin film plastics waste including subjecting the waste to oil at elevated temperature so as to effect coalescence of the waste and thereby densify and make rigid the waste into lump form for further processing.
2. A process as claimed in Claim 1 wherein the oil is sprayed onto the waste.
3. A process as claimed in Claim 2 wherein the waste is initially supplied to a weir chamber containing hot oil at elevated temperature for separating contaminants from the waste.
4. A process as claimed in any one of the preceding Claims wherein the waste in lump form is passed through de oiling rollers.
5. A process as claimed in any one of the preceding Claims wherein the oil is recirculated through heat exchange means so that the oil is maintained at a temperature necessary for coalescence.
6. A process as claimed in any one of the preceding Claims wherein the waste coalesced into lump form in a coalescing chamber and is removed therefrom by a conveyor.
7. A process for reclaiming thin film plastics waste substantially as hereinbefore described and as illustrated in the accompanying drawing.