GB2414427A

GB2414427A - Reducing contaminants in biomass material using air density separators

Info

Publication number: GB2414427A
Application number: GB0412216A
Authority: GB
Inventors: Tony Lees
Original assignee: FAIRPORT ENGINEERING GROUP Ltd
Current assignee: FAIRPORT ENGINEERING GROUP Ltd
Priority date: 2004-05-29
Filing date: 2004-05-29
Publication date: 2005-11-30
Also published as: CN1984725B; HK1083324A1; CN1984725A; GB0412216D0

Abstract

A process and apparatus for the production of a range of improved biomass material products suitable for use as a fuel and which have been derived from municipal solid waste (MSW). The process comprises the steps of delivering a stream of mixed, MSW derived biomass material (2) into a series of density separators (16, 22, 42), and directing air streams through the biomass material to entrain selected lighter components therein and to direct entrained components out of the density separators (16, 22, 42), through first outlets and, collecting the remaining MSW and directing it to second outlets (18, 26, 44) of the separators (16, 22, 42). Further disclosures relate to the specific separators, namely a heavy density separator (fig. 2), a positive density separator (fig 3) and a negative density separator (fig 5).

Description

i; Biomass Material The present invention relates to a process for the

production of a range of improved biomass material products, and in particular to the improvement of a biomass material which has been formed as a bi-product from the treatment of' municipal solid waste (MSW). The invention further relates to an apparatus for the production of' such range ot' improved biomass material products and the range of biomass materials produced thereby. The biomass material products produced are particularly suitable for use as a fuel for power generation, gasification, hospitals, industrial heating and domestic heating. The biomass materials products produced are suitable as an alternative fuel to fossil fuels, or standard biomass fuels formed from for example shredded dried wood and/or grass.

Incineration is a previously known method for the disposal of MSW. MSW generally comprises a combination of waste materials such as paper, vegetation, food, rubbers, textiles, wood, leather, plastics, glass and metals, or could contain waste from ] 5 commercial outlets for example fast-food restaurants having a substantial mix of food, plastics and paper. Combustion of the MSW produces a heat energy which, for example, can be used to produce electricity. However, burning produces ash and noxious fumes which must be contained and further processed to enable their safe disposal.

Many governments now place restrictions on the burning of fuels in order to strictly limit the amount of noxious substances released into the environment. It is therefore desirable to process the MSW in a manner which enables the separation and recovery of inorganic and organic material therefrom. The separated organic material after further processing can then be used as a fuel which can be burnt in an environmentally more friendly manner.

Traditionally it is known to separate the organic and Inorganic matters by saturating the MSW with water and/or steam, whilst heating and rotating the MSW to cause pulping of the organic material therein. The treated organic matter is then separated from the inorganic components of the waste by allowing it to fall through a screen. Examples of such processes are described in US 5,l 90,226 and US 5,556,445.

However, these known processes provide a pulped organic matter with a water lO content of between 35 /0 to 70"/0, which is extremely wet and therefore further processing is required to reduce the water content to render the pulp suitable for use as a compost or fuel. Also, the pulped material will still contain some non combustible material such as metals, rubble, glass etc. and combustible toxic materials such as plastics and rubbers which are of a size which has enabled their passage through the perforations of the screen with the thus recovered organic matter.

I'he presence of such non-combustble material and toxic materials reduces the value of the biomass fuel produced from the recovered organic matenal, since burning of such fuel still results in the production of some noxious gas and ash, lowering its potential energy density.

International Patent Application No. WO 03/092922 describes an improved method for the treatment of MSW which provides an organic pulped material having a moisture content of up to 15% which is highly suitable for further processing to i l i produce a fuel or compost. However, the improved organic pulped material is stir] separated from the non-organic components of the waste by its passage through a trommel screen, and thus still contains some non-organic and toxic components.

It is an object of the present invention to provide a method of processing organic pulped material separated from the MSW during its treatment which produces at least one high quality biomass material containing less non-organic and toxic contaminants and which has when burnt improved noxious emissions, a much reduced ash content, whilst maintaimng a good calorific value.

In accordance with a first aspect of the present invention there is provided a process for the treatment of municipal solid waste (MSW) derived biomass material to reduce the level of contaminants therein comprising the steps of: delivering a stream of mixed, MSW derived biomass material into a density separator; providing an air stream and directing it through the mixed, MSW derived biomass material in the density separator to entrain selected lighter components therein and to direct such lighter components to a first outlet ot the density separator; and collecting the remaining MSW and directing it to a second outlet of the density separator.

The air stream may be a positive pressure conveying air stream which directs the mixed, MSW derived biomass material through the density separator to the first outlet, and the step of collecting may include the provision of an adjustable separator adjacent the conveying air stream to capture and remove selected heavier components from within the stream of mixed, MSW derived biomass material.

The air stream may be directed obliquely at said stream of mixed, MSW derived biomass material, and the step of delivering may include conveying by positive pressure said mixed MSW derived biomass material through the density separator. The process may further comprise the step of distributing and separating the components of the mixed biomass material within the conveying air stream.

The step of delivering may include the step of allowing the mixed MSW derived biomass material to fall as an adjustable continuous curtain through the density separator, and the step of directing includes directing the air stream in substantially the opposite direction to the falling curtain of material.

The process may include the step of separating dust from the separated lighter components in a cyclone separator.

The process may include directing the separated lighter component from the density separator and/or cyclone to at least one further density separator and/or collection point.

The separated lighter components may be in the form of plastics and may be further separated into various component parts by adjusting the temperature and/or air flow in the separator.

Before the step of delivering the mixed, MSW derived biomass material may be sieved to remove components therein havmg a dimension greater than 50mm, more preferably I ()mm, most preferably 3mm. l l

In accordance with a second aspect of the present invention there is provided an apparatus for the treatment of municipal sohd waste (MSW) derived biomass material comprising a density separator having at least one inlet and two outlets, the inlet being adapted to admit a stream of mixed, MSW derived biomass material, at least one duct to direct the biomass material through a first of the outlets, and means to supply a current of air and direct it through the stream of biomass to separate out selected lighter components therein and to direct such to the other outlet.

The separator may be a heavy density separator and the means to supply the current of air may be a positive pressure air conveying system which directs the biomass material through the heavy density separator, the heavy density separator may further comprise an adjustable beak provided adjacent the at least one duct to enable selected heavier components of the MSW to fall from the conveying stream towards the other outlet. This has the advantage that heavier components such as glass and rubble can simply be rolled out of the stream of conveyed mixed, biomass material as it is conveyed through the separator. The density of such can be preselected by adjusting the size of the Internal beak, and/or adjusting the speed and/or quantity of air flow.

The apparatus may comprise a positive pressure air conveying system to direct the biomass material through the density separator and the separator may comprise at least one adjustable channel to respectively change the direction of flow of the biomass material strean. The separator may comprise means for directing the airflow at the stream of mixed, MSW derived biomass material as it changes direction.

1 I f I The apparatus may comprise a second inlet for admitting said current of air, and at least one air duct for directing the current of air obliquely at the stream of mixed, MSW derived biomass material.

The apparatus may include a separator in the form of a negative pressure density separator having an air mlet to direct air in substantially an opposed direction to the flow of the stream of biomass material, a duct may be provided to collect and channel the separating lighter component in the biomass material to the first outlet.

The separator may comprise a separation column through which the biomass material may freefall and may comprise an adjustable product chute to enable distribution or separation of the material into component parts.

in accordance with the third aspect of the present invention there is provided an improved biomass material product as an end product of the process for reducing contaminants in the municipal solid waste (MSW) derived biomass material. The improved biomass material product may find particular application as a fuel and may have a total moisture content of less than 1 7 X,, and/or ash content of less than 16%.

The process additionally yields a number of byproducts such as glass, rubble, plastics, and non-combustible material each ot which can be recycled and/or further processed to tonn a number of further products, or blended to provide a lower grade fuel.

By way ot example only specific embodiments of the present invention will 2() now be described with reference to the accompanying drawings, in whieh: { ; Il.

Fig. 1 is a schematic view of an apparatus for the production of an improved biomass material constructed in accordance with a first embodiment of the present invention; Fig. 2 is a sectional view of the heavy density separator of Fig. 1; Fig. 3 is a sectional view of the positive pressure density separator of Fig. 1; Fig. 4 is a schematic view of an apparatus for the production of an improved biomass material constructed in accordance with a second embodiment of the present invention; and Fig. 5 is a sectional view of the negative density separator of Fig. 4.

The starting point for the present process, in accordance with a first embodiment is the provision of a coarse mixed biomass waste material 2 produced as an end product of the treatment of municipal solid waste (MSW) and which comprises pulped organic material, and non-organc and toxic components having no dimension greater than 50mm. A suitable biomass material of such high quality is produced as an end product by the method of treatment described in international Patent AE,phcaton No. WO 03/() 92922.

Referring to Fig. I mixed biomass material 2 is fed into a storage hopper 4 for use in the process. From the hopper 4 the biomass material 2 is fed at a controlled rate and then transported via conveyors 6 into a feed hopper 8. From the feed hopper 8, via a rotary valve 10 at its outlet, the biomass material 2 is scavenge fed at entry junction 12 at a controlled rate into a positive pressure conveying system, with the propelling air being provided by conveying fan 14. l

At a first stage the mixed biomass material 2 is conveyed mto a heavy density separator 16 (to be described m more detail further herein under) in which the larger pieces of glass, ceramics, metal, rubble etc are removed using air travelling at a low velocity and by gravity separation. The thus removed inorganic components, such as glass and rubble, are discharged via a rotary valve 18 into a receiving bay 20.

The remaining mixed biomass material then passes through a positive pressure density separator 22 (to be described in more detail further herein under). At this stage of the process the combustible material is separated from the heavier non- combustible material. The heavy non-combustible material thus separated from the mixed biomass material is discharged into a receiving bay 24 via a rotary valve 26.

Secondary air which is required for this process is provided by air fan 28.

The remaining mixed biomass material 2 is then conveyed by the air flow out of the positive pressure density separator 22 into a transfer cyclone 30. The vortex created therein separates dust from the mixed biomass material 2 and discharges it through outlet 32 from where it is conveyed to dust filter 34. The remaining mixed biomass material is discharged through outlet rotary valve 36 into entry junction 38 of a positive pressure conveying system, with propelling air being provided by conveying fan 40. The mixed biomass material is then conveyed into a further positive pressure density separator 42 (to be described in more detail further herein under) which is specifically designed to take out the larger pieces of plastics from the biomass combustible material allowing the remaining mixed biomass material, the resultant high quality biomass fuel product, to discharge through rotary valve 44 into a receiving bay 46. Secondary air required for this process Is provided by fan 45.

The removal of these heavy plastics reduces the chlorine content and other noxious emissions and thereby provides an environmentally friendly, high quality biomass fuel product.

The separated pieces of plastics are conveyed into a high efficiency cyclone 48 in which the plastics are separated *om the conveying air and are discharged via rotary valve 50 into a receiving bay 52. The removed air is then directed mto the dust filter 34 which contains a fabric filter. The filtered air is emitted via exhaust fan 54, whilst the dust collected by the dust filter 34 is discharged via rotary valve 56 into a storage hopper (not illustrated) to feed to a tanker or for blending back into the fuel products.

in the heavy density separator 16, as best illustrated in Fig. 2, waste delivered from the feed hopper 8 enters via pipeline 58, which is fitted into a sealed chamber 60. The pipeline 58 has a section 62 removed *om its lower surface. A moveable section 64, fitted with an adjustable beak 66, is positioned by means of a screw rod 68 relative to the open section 62. T his arrangement allows the denser components of the mixed biomass waste to roll out of the air stream and to drop into chamber 60 for evacuation by a rotary valve 18, whilst ensuring that the lighter products remain in the air stream and continue down the pipe 58 and out of the separator 16 without being collected in the chamber 60.

In the positive density separators 22, 42, as best illustrated m Fig. 3, the mixed biomass material entering from the heavy density separator 16 or transfer cyclone 30 l ' travels from transfer duct 86 at a predetermined velocity into a vertical duct 88 and then passes into an adjustable distribution chamber 90. The distribution chamber 9() is designed to distribute and separate the products of the mixed biomass material within the conveying air stream. The separating biomass material then passes through an adjustable annulus 92, where an initial separation takes place, In that the lighter components of the biomass material turn through 180 and carries on up through a second annulus 94 and out through spigot 96. The lighter components of the biomass waste are thus conveyed upwards by secondary air 102 blown up the separator 22, 24.

The heavier components slide down cone 98 and fall mto a second separation chamber 100. As the heavier components tall down through the second separation chamber 100, the secondary air 102 is blown in the opposite direction up the chamber in order to separate out any lighter components which could not turn through 180 at the adjustable annulus 92. The thus separated lighter components Join the previously separated lighter components and exit at spigot 96. The remaining heavier components, which are generally non-combustible in density separator 22 and biomass material m separator 42 carry on down the chamber 100 and are evacuated via a rotary valve t'rom the base 104 of the conical hopper 99.

The secondary air 102 is provided via t'an 28, 45 and is fed into the system at 106 and is then Ted through a series of chambers 108, 110 to arrive at the base of the second separation chamber 100 at point 112 and at a predetermined velocity.

The size of the annulus 92 is adjusted by lit'ting or lowering the distribution chamber 90 by use of a screw 114. The geometry of the annulus 94 can be adjusted by replacing distribution chamber 90 by a larger or smaller unit 1 l 8 (shown m dotted lines). The size of the chamber lOO can be adjusted by replacing inner sleeve 116 with a smaller or larger unit.

In separator 22 the lighter, combustible waste leavmg the spigot 96 Is conveyed into the cyclone separator 30 whilst in separator 42 the lighter plastics is conveyed to cyclone separator 48.

In a second embodiment as best illustrated in Figs. 4 and 5, the starting point is the provision of a finer mixed biomass waste material produced as described with respect to the first embodiment but having no dimension greater than lOmm of non organic and toxic contaminants therein.

As best illustrated in Fig. 4 the fine biomass material I is fed into storage hopper 3 for use in the process. From the hopper 3 the biomass material I is fed at a controlled rate and then transported via conveyors 5 into a feed hopper 9.

From the feed hopper 9, via rotary valve 70 at its outlet, the fine biomass material 2 is scavenge into a negative pressure density separator 71 (to be described in more detail further hereinunder) in which the tine combustible material Is separated from the fine non-combustble material. The non-combustible material thus separated from the fine mixed biomass material is discharged mto a receiving bay 75 via a rotary valve 73.

2() The remaining fine biomass material is then conveyed In the airflow out of the negative pressure density separator into transfer cyclone 31. The vortex created therein separates dust from the fine material and discharges it through outlet 33 from . Il where it is drawn through fan 55 and then conveyed to the dust filter 34. The remaining fine mixed biomass material, the resulted fine high quality biomass fuel product is discharged via rotary valve 51 into a receiving bay 53.

In the negative density separator 71, as best Illustrated in Fig. 5 the fine mixed biomass material is fed at a controlled rate via a rotary airlock 70 onto an adjustable product feed chute 72. This converts a single stream of waste into a uniform wide band of material I that will hall as a continuous curtain of waste at junction 74 into a separation column 76.

The density separator 71 is operated under vacuum. A controlled amount of air 78 is drawn via tan 55 into the separator 71, at air inlet 8() and passes down into the Inside of the separator 71 to Junction 82, whereat it turns through 180" and flows upwards through separation column 76 In the opposite direction to the thaw of material 1. This arrangement enables the denser components of the waste to Pall down the separation column 76 and from there to be discharged via rotary valve 73.

The rotary valve 73 enables the separator to be operated under vacuum. Meanwhile the remamng lighter components of the waste are picked up in the air stream 78 moving up the separation column 76 and are carried Into an acceleration chamber 84 via a 45 bend in a transfer duct 86.

The degree of separation is controlled by adjusting the geometry of the separation column 76 to Increase or decrease the width of angles within by means of adjuster 88, 89 and/or adjusting the velocity of the airflow 78, 78 within the separation column 76.

' ; ' A chemical burn analysis of the final high quality biomass fuel product, this being a mixture of end filet products obtained *om the process -'f embodiments I and 2 described above, when compared to the mixed biomass product at the start of the process is shown in table 1. From which it is apparent that contaminants and potentially noxious components have been considerably reduced, whilst yielding a product with a good caloritic value. l;

Table I

_ Units Biomass Biomass Fuel Comments Material Product Alter Before Processing Processing Total Moisture % 15-20 12- 17 Reduced

_ _ _

Ash 'ho 15-20 10- 16 Reduced _.

Volatile Matter % 60-65 _.

Sulphur _ % 1.()-0.6 0.4-().8 Reduced Chlorine % 0.4-0.6 0.1 -0.3 Reduced

__ _

Gross CaloriiNc Kj/Kg 13- 18 13- 16 Decreased* Value _. _.

Net Calorific Value Kj/Kg 12- 16 12- 14 Decreased* _ Energy Density _ Gj/M _. 3-4 Arsenic Mg/Kg 3- 10 3-5 Reduced Dry

_

Antimony Mg/Kg 3- 10 3- 10 Dry Cadmium Mg/Kg 0.4- 1 0.2-0.5 Reduced Dry Chromium Mg/Kg 15-30 10-20 Reduced Dry Copper Mg/Kg 25-65 25-35 Reduced Dry _ _. .. _.

Lead Mg/Kg 50- 15() 50- 100 Reduced Dry. __ Mercury Mg/Kg < I 0.05-0. 2 Reduced Dry Nickel Mg/Kg 12-25 10- 15 Reduced Dry _ Vanadium Mg/Kg 25- 5() 20-30 Reduced Dry _. _ Zinc 50- 120 50- 120 _ The calorific value is slightly reduced due to the removal of plastics, plastics having a high calorific value. The reduction In plastics contaminants leads to a significant reduction In environmental pollutants such as for example chlorine.

The resultant high quality biomass fuel product is additionally environmentally friendly when compared with a fossil fuel such as coal and compares with the environmental agency limits set t'or power stations to obtain government renewable obligations certificates (ROCS) for burning biomass fuels. The results of the test conducted are shown in table 2.

Table 2

Parameter Units Environmental Blomass Fuel Coal Typical Agency Product Biomass After _L,_nits ROCS Processing _ Total Moisture % 25 12- 17 6-8 Ash 10 10-16 5- 12 Volatile Matter % 60-65 26-37 Sulphur % 0.4 0.4-0.8 0.X-3 Chlorine % 0. 4 0.1 -0.3 0.1 -0.4 _.... _ - Gross Calorific Kj/Kg 13- 16 Value _. , . ..

Net Calorific Kj/Kg > 14 12- 14 23 -31 Value Energy Gj/M3 3 -4 24 Density

_

Arsenic Mg/Kg 5 2-5 Not available Dry Antimony Mg/Kg 3- 10 Not available Dry _. _..

Cadmi urn Mg/Kg 0.2 0.2-().5 Not available Dry

__ __

Chromium Mg/Kg 30 10-20 Not available Dry

_ __

Copper Mg/Kg 50 25-35 Not available __ Dry __ Lead Mg/Kg 20 50- 100 Not available Dry

_ _

Mercury Mg/Kg 0.05 ().05-0.2 Not available Dry _. _. _ Nickel Mg/Kg 30 10- 15 Not available _ Dry. l

Table 2 cont..

Parameter Units | Environmental Biomass Fuel Coal Typical Agency Product Biomass After Limits ROCS Processing _.

Vanadium Mg/Kg 20 20-30 Not available Dry __ Zinc Mg/Kg 80 5()-120 Not available Dry _ _ As an alternative a lower range of quality fuel products can be produced by adjusting the controls in the density apparatus 22, 42. Such fuel products collected are suitable for use m gassifiers, cement and paper industries, low grade biomass fuel product for coal fired power stations, local community and industrial heating schemes, and for blending to produce other fuels such as a household fuel.

The various stages of separation each result in a different waste product. The glass and rubble received in bay 20, the non-combustible material in bay 24 and plastics in bay 52, can each be further separated for recovery and recycling of the various components therein.

Although the processes of the first and second embodiments have been described as running independently of each other, they could be combined within the same plant by either running each process side by side to produce two separate final biomass products which can be used separately or they could alternatively be combined. Or the apparatus of the second embodiment could be incorporated into the apparatus of the first embodiment, that is run m tandem, to tong a continuous process l whereby an end product of the apparatus of the first embodiment Is further refined by the apparatus of the second embodiment. Furthermore, at the end of the method of treatment of MSW described in WO 03/()92922 the mixed biomass material is passed over a trommel screen where at it is further separated into component recyclable parts.

This trommel could be arranged in two screening stages whereby biomass material having no component part greater than lOmm can fall through a first screen for further processing in the apparatus of the embodiment of Fig. 2, and remaining material which cannot pass through this fine screen then passes through a second screen which prevents component parts greater than 50mm passing therethrough. The resultant fine (no component part greater than lOmm) and coarse (no component part greater than 50mm) biomass materials can then be passed to respective storage hoppers 3 and 4 for use in the respective process described herein. Although the starting material for the first and second embodiments have been described as havmg no component part greater than 50mm and I ()mm respectively, this could be interchanged or the starting material could have components of deferent maximum dimensions.

Although the starting point of mixed biomass waste has been described as being produced by the method of treatment of MSW described in WO 03/092922, it is to be understood that the present process could be applied to other types of biomass waste. Furthermore one or more of the various stages could be omitted from the present process to achieve a lower grade biomass fuel.

Although the process has been described as separating out plastics into recevmg bay 52 using the positive density separator 42, the process could be adapted 1 1 : l i to further separate the plastics whereby adjusting the temperature and airflow within the separator recyclable plastics such as P.E.T. could be separated from the less reusable plastics such as P.V.C. At selected temperature the P.E.T. melts into and collates into a more coherent mass which can be blown into a separate collecting bay.

Recyclable plastics thus separated provide a reusable bi-product and further reduce the amount of material destined for disposal by landfill While the invention has been described in detail in terms of specific embodiments thereof, it will be apparent that venous changes and modifications can be made therein by one skilled in the art without departing from the scope thereof.

Claims

Claims A process for the treatment of municipal solid waste (MSW) derived

biomass material to reduce the level ol contaminants therein comprising the steps of delivering a stream of mixed, MSW derived biomass material into a density separator; providing an air stream and directing it through the mixed, MSW derived biomass material m the density separator to entrain selected lighter components therein and to direct such lighter components to a first outlet of the density separator; and collecting the remaining MSW and directing it to a second outlet of the density separator for collection in a receiving bay.
2. A process as claimed in claim 1, wherem the air stream is a positive pressure conveying air stream which directs the mixed, MSW derived biomass material through the density separator to the first outlet, the step of collecting includes the provision of an adjustable separator adjacent the conveying air stream to capture and remove selected heavier components front within the stream of mixed, MSW derived biomass material.
3. A process as claimed in claim], wherein the air stream is directed obliquely at said stream of mixed, MSW derived biomass material, and the step of delivering includes conveying by positive pressure said mixed MSW derived biomass material through the density separator.

:' ll; f l
4. A process as claimed in claim 3, wherein the process comprises the step of dstnbuting and separating the components of the mixed biomass material withm the conveying air stream.
5. A process as claimed in clam1 1, wherein the step of delivering includes the step of allowing the mixed MSW derived biomass material to ball as an adjustable continuous curtain through the density separator, and the step of directing includes directing the air stream in substantially the opposite direction to the falling curtain of material.
6. A process as claimed in any one of the preceding claims, wherein the process lO includes the step of separating dust *om the separated lighter components in a cyclone separator.
7. A process as claimed in any one of the preceding claims, wherein the process includes directing the separated lighter component *om the density separator and/or cyclone to at least one second density separator and/or at least one receiving bay.
8. A process as claimed in claim 7, wherein the process includes the step of using a positive, pressure air conveying stream to direct the separatett lighter components from the density separator and/or cyclone to said second density separator.
9. A process as claimed in any one of the preceding claims, wherein the separated lighter components are further separated mto component parts within the separator by adjusting the temperature and/or airflow.
10. A process as claimed in any one of the preceding claims, wherein before the step of delivering the mixed, MSW derived biomass material is sieved to remove l components therein having a dimension greater than 50mm, more preferably lOmm, most preferably 3mm.
11. An apparatus for the treatment of municipal solid waste (MSW) derived biomass material comprising a density separator having at least one inlet and two outlets, the inlet being adapted to admit a stream of mixed, MSW derived biomass material, at least one duct to direct the biomass material through a first of the outlets, and means to supply a current of air and direct it through the stream of biomass to separate out selected lighter components therein and to direct such to the other outlet.
12. An apparatus as clanged in clang 11, wherein the separator Is a heavy density 1() separator and the means to supply the current of air Is a positive pressure air conveying system which directs the biomass material through the heavy density separator, the heavy density separator comprises an adjustable beak provided adjacent the at least one duct to enable selected heavier components of the MSW to fall from the conveying stream towards the other outlet.
13. An apparatus as claimed in claim 11, wherein the separator is a positive pressure density separator and has a second mlet for admitting said current of air, and at least one air duct for directing the current of air obliquely at the stream of mixed, MSW derived biomass material.
14. An apparatus as claimed in any one of claims I I or 13, comprising a positive pressure air conveying system to direct the biomass material through the density separator and the separator comprises at least one adjustable channel to respectively l change the direction of flow of said lighter components in the biomass material stream.
15. An apparatus as claimed m claim 14, wherem the separator comprises means for directing the airflow at the stream of mixed, MSW derived biomass material as it changes direction.
16. An apparatus as claimed in claims 14 or 15, wherein the separator comprises a distribution chamber upstream of the adjustable channel.
17. An apparatus as claimed m claims 14, 15 or 16, wherein the separator comprises means to direct the airflow through the remaining stream of biomass 1 () material downstream of said adjustable channel.
18. An apparatus as claimed in claim 11, wherein the separator is a negative pressure density separator and has a second inlet for admitting said current of air, and at least one air duct for directing the current of air in substantially the opposite direction through the stream of biomass material.
19. An apparatus as claimed in claim 18, wherein the at least one duct comprises an adjustable separation column and an adjustable feed chute upstream of the adjustable separation column, the at least one air duct incorporating the separation column in its path and a transfer duct extending obliquely from the separation column to the other outlet.
20. An apparatus as claimed in any one of claims 1 1 to 19, comprising at least one cyclone having an air inlet connected to the other outlet of the separator and at least two outlets, a first of which outlets being connected to the mlet of a dust filter, the ' 1. , second of which outlets bomg connected to at least one second density separator and/or collection bay for collection of the improved biomass product.
21. An apparatus as claimed in any one of claims 11 to 20 comprising at least two density separators the other outlet ot a first of said density separators being connected to the inlet of the other density separator.
22. An apparatus as claimed in any one of claims 11 to 21, comprising at least one tan for providing a positive pressure conveying system for transforming mixed MSW biomass material at least partially through the apparatus.
23. An improved biomass material product as produced by the process as described in any one of claims I to 10.
24. An improved biomass material product as claimed m claim 23 having a gross calorific value of 13 to 16 Kj/Kg.
25. An unproved biomass material product as claimed in claim 23 or 24 having a total moisture content of 12 to 17%.
26. An improved biomass material product as claimed in claim 23, 24 or 25 having a chlorine content of less than 0.3 /0.
27. Use of an improved biomass material product as produced by the process as described in any one of claims I to 10 as a fuel for power generation.
28. A range of products produced by the process as described In any one of claims I to 10 fonned from the remaimng MSW collected in the or each recevmg bay including at least one plastics and/or glass and rubble and/or non-combustible matenal. l l;
29. A process for treatment of municipal solid waste (MSW) derived biomass material to reduce the love] of contaminants therein substantially as herein described with reference to the accompanying drawings.
30. An apparatus for the treatment of municipal sohd waste (MSW) derived biomass material to reduce the level of eontammants therein constructed and adapted to operate substantially as described herein with reference to the accompanying drawings.
31.An improved biomass material products substantially as described herem.