IES87012B2 - A method and a system for separating elements of waste materials of non-fibrous material from elements of waste materials of fibrous material in a waste materials separation system - Google Patents

Abstract

A system (1) for separating elements of waste materials of non-fibrous material from elements of waste materials of fibrous material in a waste materials separation system which separates material elements of recyclable material, comprises a materials intake building (6) which receives unsorted recyclable material elements and conveys the unsorted recyclable material elements to a materials processing building (7) where the unsorted recyclable material elements undergo a number of material pre-sorting steps and material separation steps. With the recyclable material elements sorted by material and grade of material, a first optical separator (37) is configured to displace non-fibrous material elements from fibrous material elements in a stream of elements passing through the first optical separator (37) in response to the distance detected between a non-fibrous material element and the nearest fibrous material element exceeding a predefined distance. The fibrous material elements and the remaining non-fibrous material elements in the stream of elements which pass through the first optical separator (37) are conveyed to a second optical separator (48) in which non-fibrous material elements are displaced from the stream of elements. The remaining elements which pass through the second optical separator (48) are baled into bales of fibrous material elements with fibrous material elements of a substantially similar grade of material.

Description

“A method and a system for separating elements of waste materials of non-fibrous material from elements of waste materials of fibrous material in a waste materials separation system” The present invention relates to a method and a system for separating elements of waste material elements of non-fibrous material, for example, cans, bottles and containers of ferrous and non-ferrous metals materials, bottles and containers of plastics materials and the like from elements of waste material elements of fibrous material, for example, paper, cardboard and the like in a waste materials separation system and specifically in a waste materials separation system which separates and sorts different types of recyclable material elements.

Waste materials separation systems sort and separate different types of elements of recyclable waste materials from each other, and the different types of elements of recyclable waste materials are then formed into respective bales of recyclable waste material elements for subsequent sale. It is important that each bale as well as being of a substantially similar material must also be of a substantially similar grade of material, and with little or no contamination. In general, the maximum allowable contamination level is approximately two percent. In other words the maximum amount of material allowed in a bale, which is not similar to or of a similar grade as that of the bale, is approximately two percent.

It is difficult to reach the maximum two percent contamination target. In general, the lowest contamination levels that can be achieved in known waste materials separation systems is a contamination level of not less than six percent.

Furthermore, due to inefficiencies in know separation systems a large volume of elements of otherwise recyclable material become classified as non-recyclable material waste, which in general, subsequently ends up as solid recoverable fuel. This has a negative impact on the environment and also results in the loss of otherwise elements of recyclable materials.

There is therefore a need for a system and a method for separating elements of waste materials of non-fibrous material from elements of waste materials of fibrous material in waste materials separation systems which address at least some of these issues.

The present invention is directed towards providing such a system and a method.

According to the invention there is provided a method for separating elements of waste materials of non-fibrous material from elements of waste materials of fibrous material, the method comprising sequentially urging a stream of elements of nonfibrous material and elements of fibrous material through a first separating means and a second separating means, displacing from the stream of elements in the first separating means, elements of the non-fibrous material spaced apart a distance greater than a predefined distance from the nearest element thereto of the fibrous material, and allowing the remaining non-fibrous material elements and fibrous material elements to pass through the first separating means, and displacing any remaining elements of non-fibrous material from the stream of elements in the second separating means.

Advantageously, the predefined distance in a direction parallel to the direction of travel of the stream of elements is greater than 100 millimetres, preferably, the predefined distance in the direction parallel to the direction of travel of the stream of elements is greater than 50 millimetres, and ideally, the predefined distance in the direction parallel to the direction of travel of the stream of elements is greater than 10 millimetres.

Preferably, the predefined distance in a direction transverse to the direction of travel of the stream of elements is greater than 100 millimetres, advantageously, the predefined distance in the direction transverse to the direction of travel of the stream of elements is greater than 50 millimetres, and ideally, the predefined distance in the direction transverse to the direction of travel of the stream of elements is greater than 10 millimetres.

In one aspect of the invention any remaining non-fibrous material elements in the stream of elements are displaced in the second separating means such that only elements of fibrous material remain in the stream of elements which exits the second separating means.

In another aspect of the invention the stream of elements falling under gravity onto the second separating means disperses the remaining elements of non-fibrous material from the elements of fibrous material in the stream of elements in the second separating means.

In one aspect ofthe invention the non-fibrous material elements to be displaced from the elements stream in the first separating means are displaced therefrom in response to the proximity between the non-fibrous material element and the nearest fibrous material element thereto, exceeding a distance in the range of 10 millimetres to 100 millimetres.

In another aspect ofthe invention the distance between the non-fibrous material elements and the fibrous material elements is optically detected in the first separating means. Advantageously, the distance between non-fibrous material elements and fibrous material elements in the stream of elements in the first separating means is detected by analysing an image of the stream of elements in the first separating means.

In another aspect ofthe invention the non-fibrous material elements ofthe stream of elements are optically detected in the first separating means. Advantageously, the non-fibrous material elements of the stream of elements are detected by analysing a reflected optical signal in the first separating means, and preferably, by analysing a reflected optical signal which occurs in the light spectrum.

In another aspect ofthe invention the reflected optical signal which occurs in the light spectrum is compared with a reference light spectrum, preferably, the light spectrum is an infra red light spectrum, and advantageously, a near infra red light spectrum.

In another aspect ofthe invention the non-fibrous material elements are displaced by being blown out of the stream of elements in the first separating means.

In a further aspect of the invention the stream of elements is urged through the first separating means on a conveyer.

Advantageously, the first separating means comprises an optical separator.

In another aspect of the invention the non-fibrous material elements and the fibrous material elements pass through the first separating means in response to the first separating means detecting at least one of -a non-fibrous material element being located immediately adjacent a fibrous material element, or -one of a non-fibrous material element and a fibrous material element overlapping the other one of a non-fibrous material element and a fibrous material element, or -a non-fibrous material element being located on a fibrous material element such that a peripheral edge of the fibrous material element substantially surrounds a peripheral edge of the non-fibrous material element.

In another aspect of the invention the non-fibrous material elements of the stream of elements are optically detected in the second separating means. Advantageously, the non-fibrous material elements of the stream of elements are detected by analysing a reflected optical signal in the second separating means, and preferably, by analysing a reflected optical signal which occurs in the light spectrum.

In another aspect of the invention the reflected optical signal which occurs in the light spectrum is compared with a reference light spectrum, preferably, the light spectrum is an infra red light spectrum, and advantageously, a near infra red light spectrum.

In another aspect of the invention the non-fibrous material elements are displaced by being blown out of the stream of elements in the second separating means.

In a further aspect of the invention the stream of elements is urged through the second separating means on a conveyer.

Advantageously, the second separating means comprises an optical separator.

In one aspect of the invention the displaced non-fibrous material elements are displaced into a second stream of elements which comprises elements of nonfibrous material and elements of fibrous material.

In another aspect of the invention the second stream of elements is sequentially urged through a density separating means, preferably, the density separating means separates elements from the second stream of elements based on the weight of the elements in the second stream.

In another aspect of the invention the elements located in the second stream with a weight greater than a predefined weight are displaced from the second stream in the density separating means, preferably, the elements which pass through the density separating means are of a weight less than or equal to the predefined weight, advantageously, the predefined weight is in the range of 50 grams to 1000 grams, and preferably, the predefined weight is 100 grams.

In another aspect of the invention the elements of the second stream with a weight less than or equal to the predefined weight are convoyed on an updraught of air, from an infeed conveyor onto a rotational element, and ideally, the elements of the second stream with a weight less than or equal to the predefined weight pass over a highest portion of the rotational element.

In a further aspect of the invention the density separating means comprises a density separator.

In a further aspect of the invention the elements of the second stream are sequentially urged through a third separating means, preferably, the third separating means displaces fibrous material elements from the second stream in the third separating means in response to the third separating means detecting fibrous material.

In another aspect of the invention the fibrous material elements of the second stream of elements are optically detected in the third separating means. Advantageously, the fibrous material elements of the second stream of elements are detected by analysing a reflected optical signal in the third separating means, and preferably, by analysing a reflected optical signal which occurs in the light spectrum. Advantageously, the reflected optical signal which occurs in the light spectrum is compared with a reference light spectrum, preferably, the light spectrum is an infra red light spectrum, and ideally, a near infra red light spectrum.

In another aspect of the invention the fibrous material elements are displaced in the third separating means by being blown out of the second stream of elements.

Advantageously, the third separating means comprises an optical separator.

In a further aspect of the invention the elements of the second stream are urged through the third separating means on a conveyer.

In a one aspect of the invention the elements of the second stream and a third stream of elements which comprises elements of non-fibrous material and elements of fibrous material are urged through the third separating means on the conveyer, preferably, the elements of the second stream and the elements of the third stream are segregated on the conveyer, and ideally, the third separating means displaces fibrous material elements from the third stream.

In another aspect of the invention the fibrous material elements of the third stream of elements are displaced in the third separating means by being blown out of the third stream of elements.

In another aspect of the invention the fibrous material elements of the third stream of elements are optically detected in the third separating means.

The invention also provides a system for separating elements of waste materials of non-fibrous material from elements of waste materials of fibrous material in a waste materials separation system, the system comprising a first separating means and a second separating means configured to carry out a method according to the invention for separating elements of waste materials of non-fibrous material from elements of waste materials of fibrous material.

The advantages of the invention are many. A particularly important advantage of the invention is that by virtue of the fact the first separating means displaces elements of non-fibrous material from elements of fibrous material based on the distance between non-fibrous material elements and the nearest fibrous material element in a stream of elements, and the second separating means displaces any remaining elements of non-fibrous material from the stream of elements passing through the second separating means regardless of the distance between a non-fibrous material element and any fibrous material element in the second separating means, means the accuracy of first and second separating means for displacing non-fibrous material elements from a stream of elements is controlled so the volume of nonfibrous material elements which exit the second separating means is greatly reduced or even eradicated which in turn reduces the level of contamination that remains in the stream of elements that exit the second separating means which are to be baled.

A further advantage of the invention is, by locating a density separator and a third separating means which displaces fibrous material elements from a stream of elements which comprise elements of non-fibrous material and elements of fibrous material, the level of recovery of fibrous material elements which can be baled is greatly increased which in turn greatly reduces the volume of elements of fibrous material being classified as non-recyclable material waste and subsequently ending up as solid recoverable fuel.

The invention will be more clearly understood from the following description of a preferred embodiment thereof, which is given by way of example only, with reference to the accompanying drawings, in which: Fig. 1 is a block representation of a system according to the invention for separating elements of waste materials of non-fibrous material from elements of waste materials of fibrous material in a waste materials separation system, Fig. 2 is a side elevation view of one detail of the system of Fig. 1, Fig. 3 is a top plan view of the detail of Fig. 2 of the system of Fig. 1, Fig. 4 is a side elevation view of another detail of the system of Fig. 1, Fig. 5 is a top plan view of the detail of Fig. 4 of the system of Fig. 1, Fig. 6 is a side elevation view of another detail of the system of Fig. 1, Fig. 7 is a top plan view of.the detail of Fig. 6 of the system of Fig. 1, Fig. 8 is a side elevation view of a further detail of the system of Fig. 1, Fig. 9 is a side elevation view of a still further detail ofthe system of Fig. 1, and Fig. 10 is a top plan view ofthe detail of Fig. 9 ofthe system of Fig. 1.

Referring to the drawings there is illustrated a waste materials separation system according to the invention indicated by the reference numeral 1, for separating elements of recyclable fibrous materials from elements of recyclable non-fibrous materials, and for forming the elements of similar fibrous material and a similar grade of material into respective bales. In this embodiment ofthe invention, the elements of recyclable fibrous material comprise, for example, elements of paper and cardboard, such as cardboard containers, boxes and other paper and cardboard elements. The elements of recyclable non-fibrous material comprise, for example, elements of ferrous and non-ferrous metals materials and plastics materials, such as metal containers and cans, plastic containers and bottles of natural and coloured highdensity polyethylene material, polyethylene terephthalate material and other recyclable plastics material.

The waste materials separation system comprises two buildings, namely, a materials intake building 6 and a materials processing building 7, neither of which are shown but are represented by the broken lines 6 and 7 in Fig. 1. The materials intake building 6 is configured to receive and store both unsorted bagged elements of recyclable material and loose unsorted elements of recyclable material for recycling. The materials processing building 7 is configured to sort and separate the elements of recyclable materials and to form the sorted and separated elements of recyclable materials into respective bales thereof. A series of materials pre-sorting processes and materials separation processes located in the materials processing building 7 are configured to sort and separate fibrous material elements from non-fibrous material elements by processing the unsorted elements of recyclable materials from the materials intake building 6.

The materials intake building 6 comprises material conveying lines, namely, first conveying line 10 and second conveying line 11 which convey a respective stream of unsorted recyclable materials elements from the materials intake building 6 to the materials processing building 7. A third conveying line 12 is provided in the materials intake building 6 in which the bagged elements of recyclable material are debagged and delivered onto the first conveying line 10. The first and second conveying lines 10 and 11 deliver a stream of unsorted recyclable materials elements to respective first sorting screens 14a and 14b which are similar to each other and are located in the materials processing building 7.

Each first sorting screen 14a and 14b is configured to displace elements with at least one dimension greater than 0.45 meters, for example, large cardboard elements from the corresponding stream of elements. The displaced elements are discharged from the first sorting screens 14a and 14b onto a displaced material conveying line 15. The remaining elements which pass through the respective first sorting screens 14a and 14b are delivered on conveyers 16a and 16b through manual pre-sorting stations 17a and 17b. The stream of displaced large cardboard elements from the first sorting screens 14a and 14b are conveyed through a manual material presorting station 17c on displaced material conveying line 15.

The remaining elements on conveyers 16a and 16b have elements of film material and elements of solid recoverable material manually removed therefrom in the corresponding manual material pre-sorting station 17a and 17b. Displaced material conveying line 15 has any non-cardboard material elements manually removed therefrom in the manual material pre-sorting station 17c. The elements of cardboard material which pass through the manual material pre-sorting station 17c are delivered to cardboard material storage for subsequent formation into bales of cardboard material elements in a bale forming apparatus 21.

The stream of elements on conveying lines 16a and 16b which pass through the respective manual material pre-sorting stations 17a and 17b are conveyed from the corresponding manual material pre-sorting stations 17a and 17b through a series of respective material pre-sorting screens, namely, second, third and fourth sorting screens 18a and 18b, 19a and 19b and 20a and 20b which each carry out an imprecise material sorting and grading process.

The second sorting screens 18a and 18b are similar to each other and are configured to displace elements with a maximum dimension of 24 millimetres, for example, glass fines from the corresponding stream of elements passing therethrough, and convey the remaining elements of the stream through the corresponding second sorting screen 18a and 18b. The displaced fines material is conveyed to fines storage for subsequent removal from site. The remaining elements in each respective stream of elements which pass through the second sorting screens 18a and 18b, are delivered from the corresponding second sorting screen 18a and 18b to corresponding third sorting screens 19a and 19b.

The third sorting screens 19a and 19b are similar to each other and are configured to displace fibrous material elements such as paper with at least one dimension greater than 200 millimetres from the respective stream of remaining elements. The third sorting screens 19a and 19b may also displace non-fibrous material elements with at least one dimension greater than 200 millimetres, for example, elements of film material, plastic bottles and containers, and metal cans and containers. All the displaced materials from the third sorting screens 19a and 19b, both fibrous and non-fibrous material elements are conveyed from the respective third sorting screens 19a and 19b and join a single high quality grade paper conveying line 22. The remaining material elements which pass through the corresponding third sorting screens 19a and 19b are conveyed to respective fourth sorting screens 20a and 20b.

The fourth sorting screens 20a and 20b are similar to each other and are configured to displace any remaining fibrous material elements with at least one dimension greater than 100 millimetres from the respective remaining stream of elements. The fourth sorting screens 20a and 20b may also displace non-fibrous material elements with at least one dimension greater than 100 millimetres, for example, elements of film material, plastic bottles and containers, and metal cans and containers. All the displaced materials from the fourth sorting screens 20a and 20b are conveyed from the respective fourth sorting screens 20a and 20b and join a single low quality grade paper conveying line 23.

Such material pre-sorting processes will be well known to those skilled in the art and further description is not required.

The remaining elements in the corresponding stream of elements which pass through the corresponding fourth sorting screens 20a and 20b, comprise predominantly non-fibrous material elements, for example, plastic bottles and containers, metal cans and containers, and may also comprise fibrous material elements, for example, small pieces of paper. The remaining elements from each corresponding stream of elements which pass through fourth sorting screens 20a and 20b are combined into a single stream of elements and join a single recovery conveying line 25. The stream of elements which join the recovery conveying line 25 is conveyed through a metals and plastics recovery process 26.

In the metals and plastics recovery process 26 the stream of elements on the recovery conveying line 25 are sequentially urged under a recovery over belt magnet 28 which is configured to displace non-fibrous material elements of ferrous metal material from the stream of elements on recovery conveying line 25, over a recovery eddy current generator 29 which is configured to displace non-fibrous material elements of non-ferrous metal material from the stream of elements on recovery conveying line 25 and through three consecutive recovery optical separators, namely, first, second and third recovery optical separators 31, 32 and 33 which are each configured to displace different types of non-fibrous material elements of plastics material from the stream of elements on the recovery conveying line 25.

The first recovery optical separator 31 is configured to displace non-fibrous material elements of high-density polyethylene material from the stream of elements on the recovery conveying line 25, the second recovery optical separator 32 is configured to displace non-fibrous material elements of polyethylene terephthalate material from the stream of elements on the recovery conveying line 25 and the third recovery optical separator 33 is configured to displace non-fibrous material elements of other recyclable plastics materials from the stream of elements on the recovery conveying line 25.

Such a metals and plastics recovery process will be well known to those skilled in the art and further description is not required.

The remaining elements in the stream of elements on the recovery conveying line 25 which pass through the metals and plastics recovery process 26 are conveyed from the metals and plastics recovery process 26 and delivered to a separation process which will be described below.

The single low quality grade paper conveying line 23 has a stream of elements of fibrous material elements and non-fibrous material elements located thereon. The non-fibrous material elements are considered as contaminants and require separation from the fibrous material elements before formation of the fibrous material elements into low quality grade paper bales. The non-fibrous material elements are separated from the fibrous material elements of low quality grade paper in a series of materials separation processes.

The stream of elements on the low quality grade paper conveying line 23 are conveyed from the fourth sorting screens 20a and 20b under an over belt magnet 35 which removes non-fibrous material elements of ferrous metal material from the stream of elements on the low quality grade paper conveying line 23, and over an eddy current generator 36 which removes non-fibrous elements of non-ferrous metal material from the stream of elements on the low quality grade paper conveying line 23.

The stream of elements which pass through the over belt magnet 35 and the eddy current generator 36 are divided into two separate streams of elements on conveyors 34a and 34b. Each conveyor 34a and 34b delivers each corresponding stream of elements to a respective first separating means comprising a first optical separator 37.

Each of the first optical separators 37a and 37b are similar to each other and are programmed to displace non-fibrous material elements from the stream of elements in response to the distance between a non-fibrous material element and the nearest fibrous material element exceeding a predefined distance. In this embodiment of the invention the predefined distance is 10 millimetres. The displaced non-fibrous material elements from each first optical separator 37a and 37b are delivered to a conveying line 38 which conveys the displaced elements from the first optical separators 37a and 37b to a density separator for further material separation, which will be described below.

In this embodiment of the invention each first optical separator 37a and 37b is programmed to allow non-fibrous material elements and the fibrous material elements pass through the corresponding first optical separator 37a and 37b in response to the first optical separator 37 detecting at least any of the following: -that a non-fibrous material element is located immediately adjacent a fibrous material element, or -that one of a non-fibrous material element or a fibrous material element is overlapping the other one of a non-fibrous material element or a fibrous material element, or -that a non-fibrous material element is located on a fibrous material element with a peripheral edge of the fibrous material element substantially surrounding a peripheral edge of the non-fibrous material element.

The non-fibrous material elements which are not displaced from the stream of elements in the first optical separator 37, pass through the first optical separator 37 and are delivered to a conveying line 41 which conveys the remaining non-fibrous material elements and the fibrous material elements to a second optical separator 48 for further material separation.

Referring now to Figs. 2 and 3, one of the first optical separators 37a and 37b is illustrated together with a downstream end of one of the conveyors 34a and 34b.

The first optical separator 37 comprises a mechanically driven infeed conveyer 39 which conveys the corresponding stream of elements sequentially through the first optical separator 37. The corresponding stream of elements is delivered onto the infeed conveyer 39 under gravity from the downstream end of the conveyer 34, as shown in Fig. 2.

An infra red detector 40 mounted above the infeed conveyer 39 monitors the stream of elements being conveyed sequentially along the infeed conveyer 39 across the full width of the infeed conveyer 39. The infra red detector 40 generates a signal indicative of a fibrous material which identifies those elements which are of fibrous material and generates a signal indicative of a non-fibrous material which identifies those elements which are of non-fibrous material. A camera 45 of the infra red detector 40 monitors the distance between fibrous material elements and non-fibrous material elements on the infeed conveyer 39 and determines when the distance between a non-fibrous material element and the nearest fibrous material element is greater than 10 millimetres.

An pneumatic ejector 42 comprising a plurality of air jets 43 which extend across the width of the infeed conveyor 39 in a matrix formation, is operated under the control of a control circuit 46 of the infra red detector 40 which responds to signals read from the infra red detector 40 to displace elements over the conveying line 41 onto the conveying line 38.

Upon the infra red detector 40 detecting a non-fibrous material element and determining that the distance of the nearest fibrous material element is greater than a distance of 10 millimetres from the detected non-fibrous material element, the control circuit 46 generates an activation signal which identifies air jets 43 that intersect a locus of travel of the detected non-fibrous material element to be displaced from the infeed conveyer 39. The activation signal also determines when each identified air jet 43 is to be activated.

Upon the ejector 42 receiving the activation signal from the control circuit 46, compressed air from a compressor 47 is directed to the corresponding air jets 43 which intersect the locus of travel of the detected non-fibrous material element to be displaced. A valve (not shown) in each corresponding air jet 43 is opened at the determined time such that the corresponding air jets 43 generate a stream of air which displaces the detected non-fibrous material element from the stream of elements and blows the non-fibrous material element over the conveying line 41 to the conveying line 38 for further material separation processing which will be described below.

Conveying line 41 combines the stream of elements of fibrous material elements and non-fibrous material elements which pass through each first optical separator 37a and 37b and delivers the combined stream of elements to the second optical separator 48.

The second optical separator 48 is substantially similar to each ofthe first optical separators 37a and 37b and operates in a substantially similar manner as the first optical separators 37a and 37b with the exceptions that second optical separator 48 is programmed to displace any remaining non-fibrous material elements from the combined stream of elements regardless of the distance between a non-fibrous material element and any fibrous material element in the stream of elements, and the width of an infeed conveyer 49 of the second optical separator 48 is greater than the width of the infeed conveyer 39 of each first optical separator 37a and 37b. In this embodiment of the invention the width of the infeed conveyer 39 of each first optical separator 37a and 37b is approximately 2 meters and the width of the infeed conveyer 49 of the second optical separator 48 is approximately 2.8 meters.

Referring now to Figs. 4 and 5, the second optical separator 48 is illustrated together with a downstream end of the conveying line 41. The infeed conveyer 49 of the second optical separator 48 is mechanically driven and conveys the combined stream of fibrous material elements and non-fibrous material elements through the second optical separator 48. The combined stream of elements is delivered onto the infeed conveyer 49 of the second optical separator 48 under gravity from the downstream end of the conveying line 41, as shown in Fig. 4. The gravity feed of the stream of elements onto the infeed conveyer 49 is configured to disperse the remaining fibrous material elements from the remaining non-fibrous material elements in the stream of elements on the infeed conveyer 49.

An infra red detector 51 of the second optical separator 48 monitors the stream of elements across the full width of the infeed conveyer 49, and upon a control circuit 53 of the infra red detector 51 detecting a non-fibrous material element on the infeed conveyer 49, an activation signal is generated and sent to a pneumatic ejector 50 which activates corresponding air jets 52 to displace the detected non-fibrous material element from the stream of elements and blows the non-fibrous material element over conveying line 54 to conveying line 38. Conveying line 38 is configured to deliver the displaced elements from the second optical separator 48 to a further material separation process which will be described below.

Conveying line 54 receives the remaining elements of the stream of elements which pass through the second optical separator 48 and conveys the remaining elements through a first quality control station 55, in which any remaining non-fibrous material elements that remain in the stream of elements are manually removed therefrom. Upon exiting the first quality control station 55, the stream of elements on conveying line 54 now contains less than 0.5% non-fibrous material elements. Conveying line 54 delivers the remaining stream of elements located thereon, to a bale forming apparatus 21 for formation into bales of low quality grade paper elements.

The combined stream of elements from the third sorting screens 19a and 19b which comprises non-fibrous material elements with at least one dimension greater than 200 millimetres and fibrous material elements with at least one dimension greater than 200 millimetres are conveyed on the high quality grade paper conveying line 22 to a primary optical separator 56. The non-fibrous material elements located on the high quality grade paper conveying line 22 are considered as contaminants and require removal from the stream of elements in the primary optical separator 56.

The primary optical separator 56 is substantially similar to the second optical separator 48 and operates in a substantially similar manner as the second optical separator 48.

Referring now to Figs. 6 and 7, the primary optical separator 56 is illustrated together with a downstream end of the high quality grade paper conveying line 22. The primary optical separator 56 comprises a mechanically driven infeed conveyer 57 which conveys the corresponding stream of elements sequentially through the primary optical separator 56. The corresponding stream of elements is delivered onto the infeed conveyer 57 under gravity from the downstream end of the high quality grade paper conveying line 22, as shown in Fig. 6.

An infra red detector 58 of the primary optical separator 56 monitors the stream of elements across the full width of the infeed conveyer 57, and upon the infra red detector 58 detecting a non-fibrous material element on the infeed conveyer 57, an activation signal is generated and sent to a pneumatic ejector 59 which activates corresponding air jets 60 of the pneumatic ejector 59 to displace the detected nonfibrous material element from the stream of elements and blows the non-fibrous material element over conveying line 62 to conveying line 38, conveying line 38 is configured to deliver the displaced elements from the primary optical separator 56 to a further material separation process which will be described below.

Conveying line 62 receives the remaining elements of the stream of elements which pass through the primary optical separator 56 and conveys the remaining elements through a second quality control station 64, in which any remaining non-fibrous material elements that remain in the stream of elements are manually removed therefrom. Upon exiting the second quality control station 64 the stream of elements on conveying line 62 now contains less than 0.5% non-fibrous material elements. Conveying line 62 delivers the remaining stream of elements located thereon, to a bale forming apparatus 21 for formation into bales of high quality grade paper elements.

Conveying line 38 conveys the displaced elements from the first optical separators 37a and 37b, the second optical separator 48 and the primary optical separator 56, to an infeed conveyer 69 of a density separating means which comprises a density separator 65. The stream of elements located on the conveying line 38 comprises non-fibrous material elements, and may contain some fibrous material elements, for example, smaller pieces of paper which may have been displaced with non-fibrous material elements in the corresponding optical separators.

The density separator 65 is configured to displace elements with a weight less than or equal to a predefined weight from elements with a weight greater than the predefined weight. In this embodiment of the invention the predefined weight is 100 grams.

Referring now to Fig. 8, in which the density separator 65 is illustrated. The density separator 65 comprises the infeed conveyer 69, a fan apparatus 70 that is located at a level lower than the infeed conveyer 69 and is configured to generate an updraught of air upon which elements with a weight less than or equal to 100 grams are conveyed across a gap 71 onto a rotational element, namely, a rotational drum 72 and over the rotational drum 72. A highest portion 75 of the rotational drum 72 is located at a height greater than the height of the infeed conveyer 69 so that the rotational drum 72 acts as barrier and prevents elements with a weight greater than 100 grams from passing over the rotational drum 72. The elements which pass over the rotational drum 72 are delivered onto conveying line 73 and form a light faction stream of elements 66. The elements which do not pass over the rotational drum 72, pass through the air updraught of the fan apparatus 70 and fall through a chute 74 onto conveying line 76 to form a heavy faction stream of elements 67.

The light faction stream of elements 66 comprises lighter material elements, for example, fibrous material elements of smaller pieces of paper and non-fibrous material elements of plastics film material, and the heavy faction stream of elements 67 comprises heavier non-fibrous material elements, for example, cans, bottles and plastics containers.

The location of the infeed conveyer 69 is selectable and movable relative to the location of the fan apparatus 70. The location of the fan apparatus 70 is selectable and movable relative to the location of the infeed conveyer 69. The speed of the fan apparatus 70 is also manually selectable which in turn determines the force of the air updraught generated by the fan apparatus 70. The force required by the air updraught from the fan apparatus 70 is determined based on the predefined maximum weight of the elements which are to form the light faction stream of elements 66 and the spacing of the gap 71 between the infeed conveyer 69 and the rotational drum 72. The speed of rotation and the height of the rotational drum 72 are also manually selectable.

Conveying line 76 conveys the heavy faction stream of elements 67 from the density separator 65 to the metals and plastics recovery process 26 and delivers the heavy faction stream of elements 67 to the recovery conveying line 25 where the heavy faction stream of elements 67 is combined with the stream of elements on the recovery conveying line 25.

Conveying line 73 conveys the light faction stream of elements 66 from the density separator 65 and delivers the light faction stream of elements 66 to a third separating means which comprises a third optical separator 80.

The third optical separator 80 is substantially similar to the second optical separator 48 and operates in a substantially similar manner as the second optical separator 48 with the exception that the third optical separator 80 is programmed to displace fibrous material elements from the stream of elements located on a divided infeed conveyer 81 in response to the third optical separator 80 detecting fibrous material on the divided infeed conveyer 81.

Referring now to Figs. 9 and 10, the third optical separator 80 is illustrated together with a downstream end of conveying line 73 and a downstream end of recovery conveying line 25. The mechanically driven divided infeed conveyer 81 comprises two segregated lanes, namely, a first lane 83 and a second lane 84. The first lane 83 receives the light faction stream of elements 66 from the conveying line 73 and the second lane 84 receives the remaining elements from the recovery conveying line 25 which have passed through the metals and plastics recovery process 26.

An infra red detector 87 of the third optical separator 80 monitors the stream of elements across the full width of the divided infeed conveyer 81, and upon the infra red detector 87 detecting a fibrous material element on the divided infeed conveyer 81, an activation signal is generated and sent to a pneumatic ejector 88 which activates corresponding air jets 89 of the pneumatic ejector 80 to displace the detected fibrous material element from the stream of elements and blows the fibrous material element over waste conveying line 91 to conveying line 92.

Waste conveying line 91 receives the remaining elements of the stream of elements which pass through the third optical separator 80 and conveys the stream of elements located thereon to waste storage.

Conveying line 92 conveys the displaced elements from the third optical separator 80 through a third quality control station 94, in which any remaining non-fibrous material elements that remain in the stream of elements on conveying line 92 are. manually removed therefrom. Upon exiting the third quality control station 94 the stream of elements on conveying line 92 now contains less than 0.5% non-fibrous material elements. Conveying line 92 delivers the remaining stream of elements located thereon, to a bale forming apparatus 21 for formation into bales of low quality grade paper elements.

While in the embodiment of the invention described with reference to Figs. 1 to 10, the first and second optical separators 37a, 37b and 48 of the system 1 have been described as configured to remove contaminants of non-fibrous material elements from the stream of elements of the high quality grade paper line and the low quality grade paper line, respectively, it will be appreciated that the first and second optical separators 37a, 37b and 48 may be configured for displacing any other type of detectable material from a stream of elements which comprise elements of a specified material to be recovered in order to reduce the contamination level in a bale of elements of the specified material to be recovered.

It will be appreciated that the first and second optical separators 37a, 37b and 48 may be configured to displace elements of fibrous material, of ferrous material, of non-ferrous material, of polyethylene terephthalate material and other recyclable plastics material elements from high-density polyethylene material elements in order to reduce the contamination level in a bale of high-density polyethylene material elements.

It will also be appreciated that the first and second optical separators 37a, 37b and 48 may be similarly configured to reduce the contamination level in a bale of polyethylene terephthalate material elements.

It will also be appreciated that while the predefined distance of the first optical separators has been described in this embodiment of the invention as being 10 millimetres, any suitable predefined distance value of the first optical separators may be selected, and possibly a predefined distance value less than 10 millimetres may be selected.

While the fan apparatus of the density separator has been described as being located below the level of the infeed conveyer in order to generate an updraught to divide the elements passing through the density separator between a light faction stream of elements and a heavy faction stream of elements, it will be appreciated that dividing of the stream of elements into a light and heavy faction may be achieved by any suitable means and possibly by providing a vacuum apparatus to generate an updraught above the level ofthe infeed conveyer.

The invention is not limited to the embodiment hereinbefore described which may be 5 varied in construction and detail.

Claims (5)

1. A method for separating elements of waste materials of non-fibrous material from elements of waste materials of fibrous material, the method comprising sequentially urging a stream of elements of non-fibrous material and elements of fibrous material through a first separating means and a second separating means, displacing from the stream of elements in the first separating means, elements of the non-fibrous material spaced apart a distance greater than a predefined distance from the nearest element thereto of the fibrous material, and allowing the remaining nonfibrous material elements and fibrous material elements to pass through the first separating means, and displacing any remaining elements of non-fibrous material from the stream of elements in the second separating means.

2. A method as claimed in Claim 1 in which the predefined distance, in a direction parallel to the direction of travel of the stream of elements and in a direction transverse to the direction of travel of the stream of elements, is greater than 10 millimetres.

3. A method as claimed in Claim 1 or 2 in which any remaining non-fibrous material elements in the stream of elements are displaced in the second separating means such that only elements of fibrous material remain in the stream of elements which exits the second separating means.

4. A method as claimed in any preceding claim in which the stream of elements falling under gravity onto the second separating means disperses the remaining elements of non-fibrous material from the elements of fibrous material in the stream of elements in the second separating means.

5. A system for separating elements of waste materials of non-fibrous material 5 from elements of waste materials of fibrous material in a waste materials separation system, the system comprising a first separating means and a second separating means configured to carry out a method as claimed in any preceding claim.