AU779714B2 - Process for treating biomass fibrous material - Google Patents

Description

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION STANDARD PATENT a a Applicant(s): STAR POWER INTERNATIONAL HOLDINGS LTD.

Invention Title: PROCESS FOR TREATING BIOMASS FIBROUS MATERIAL The following statement is a full description of this invention, including the best method of performing it known to me/us: 2 PROCESS FOR TREATING BIOMASS FIBROUS MATERIAL Technical Field This invention relates to a process for the manufacture of multiple valuable products from processing biomass fibrous material especially waste products such as those generated during the processing of sugar cane.

Background Art The sugar cane industry generates vast quantities of wastes and residues during the production of its primary product. These include sugar cane bagasse and liquor streams containing large quantities of low grade sugars.

Bagasse is usually burned inefficiently in boilers to generate steam and power. The liquid waste streams, mostly molasses, are usually sold as low grade cattle feed.

The sugar cane industry is presently low in profits. One approach to reverse this situation is to convert these wastes and residues into saleable products that can add to the revenues of the industry.

The value of this approach has been recognised in recent years and considerable research has been undertaken to identify useful products that can be generated from these wastes.

A new type of pulping technology, known as organosolv pulping, has distinct advantages for the sugar cane industry. It has almost no environmental problems, is less capital intensive than kraft, it produces multiple coproducts, is ideally suited to pulping non-wood biomass that contain high levels of inorganic materials, and can be profitably operated on a much smaller scale than conventional pulping processes. Even more attractive for the sugar cane industry is its compatibility with an agricultural economy. One of its primary process chemical needs is ethanol, which can be easily produced by fermentation of waste sugars and starch. Furthermore, many of the co-products of the process find immediate use and \\melbfiles\home$\Luisa\Keep\Speci\AU Process for treating biomass fibrous material Skrine.doc 8/08/00 3 value in agriculture, such as animal feed supplements and slow release fertiliser and pesticides. Integration in a single mill of organosolv pulping of biomass residues with the processing and fermentation of aqueous waste streams will result in major profits for the sugar cane industry.

At the same time such a strategy will result in a high degree of environmental protection and support for the development of adjacent industrial activities based on the co-products of this process.

Summary of the Invention In a first aspect the present invention provides .a process for delignifying biomass fibrous material comprising: digesting biomass fibrous material in a liquor comprising a mixture of alcohol (such as ethanol) and water at elevated temperature and pressure for a time sufficient to at least partially delignify the biomass fibrous material and form a pulp, 20 separating spent liquor from the pulp, washing the pulp with a fresh mixture of alcohol and water, recovering the fresh mixture of alcohol and water to be recycled as the liquor, 25 reducing the pressure to cause alcohol and water remaining with the pulp to partially or fully evaporate, recovering the pulp, o reducing the pressure of the spent liquor to OV0* enable volatile material to evaporate and be recovered, thereby leaving a lignin-rich condensed liquor, diluting the condensed liquor with aqueous stillage, lowering the pH of the condensed liquor to below 3 and cooling the condensed liquor to cause lignin to precipitate from a mother liquor, separating lignin from the mother liquor, distilling the delignified mother liquor to recover ethanol and furfural therefrom leaving the aqueous H:\susanp\keep\STAR ?OWER 51888-00 amended pgs.doc 9/12/04 3a stillage, allowing the aqueous stillage to settle removing oily and waxy substances from an upper layer of the aqueous stillage thereby leaving an aqueous layer containing xylose, xylan and other sugars, and fermenting the aqueous layer to produce ethanol.

The process may include the step of treating spent liquor from the spent liquor tank to recover lignin, acetic acid, furfural, xylose and other co-products, as well as recovering alcohol for re-use in the process and subjecting various liquid waste streams of the process and from a sugar cane mill to fermentation in order to produce ethanol and other fermentation products which may be used in the process.

In a second aspect the invention provides an ooeo* o* o* oo *o H:\susanp\keep\STAR POWER 51888-00 amended pgs.doc 9/12/04 4 integrated process for producing pulp and ethanol from biomass, the process including the steps of: digesting biomass fibrous material in a liquor comprising a mixture of ethanol and water to produce a pulp and spent liquor, separating pulp from the spent liquor, recovering ethanol from the spent liquor, and fermenting an extract from the spent liquor and/or effluent from upstream processing of the biomass to produce ethanol.

This process concept is applicable to other biomass residues as well as cane-sugar residues. The potential advantages of integrating these two formerly separate activities into a single operating unit are numerous. They include lower total capital costs, combining different liquor streams for common product recovery, opportunities for process heat and energy reduction, internal process chemical production, reduced transportation costs, substantial environmental improvement and the potential for the use of larger, more efficient equipment in a shared operation. Separate facilities operating in isolation may not be economic. This identifies the unit processes and the product flows in an integrated total process that would provide these 25 advantages to the sugar cane industry.

Methanol may also be used together with or as a replacement for ethanol especially when its price is low.

Fresh, wet bagasse is brought to the processing plant in a conventional manner. In a preferred embodiment, the water saturated bagasse is transferred to a batch digester and pulped with aqueous ethanol at an appropriate concentration (35%-65% w/w) for about 1-2 hr, at 175°- 185 0 C. This cooking can be done either in one or two stages depending on the type of pulp and properties required. Following cooking, part of the liquor is pumped from the digester to a spent liquor tank and the pulp and some of the liquor is blown from the digester. The spent \\melbfiles\home$\Luisa\Keep\Speci\AU Process for treating biomass fibrous material Skrine.doc 8/08/00 5 liquor is pumped to a flash tank from which the alcoholrich vapours are condensed and recovered.

Following removal of the pulp from the digester, the brown-stock bagasse pulp may be passed through a refiner or hydropulper, screened and cleaned by conventional pulp processing equipment and sent on to a bleach plant of appropriate design for the type of pulp desired as the final product. It should be noted here that ethanol-based organosolv pulps are normally more easily bleached than kraft pulps and therefore the bleach plant could be of relatively simple design. Furthermore, organosolv pulps generally have a yield advantage over kraft pulps. The combined effluent from the bleaching stages can then be treated by wet oxidation to 15 produce sodium acetate for sale as a commodity chemical.

Because of the integrated nature of the process, wet oxidation of other high BOD concentrated effluents derived from the sugar refining operations can be carried out simultaneously or sequentially in the same equipment. This would avoid the installation of large-scale effluent treatment systems and furthermore convert a costly treatment step into a revenue source.

The spent aqueous ethanol liquors recovered from the digester are concentrated in the flash tank and 25 combined with acidified stillage from the distillation tower. Acetic acid obtained from a later stage could be used for this acidification. Upon dilution with the acidified stillage, bagasse lignin precipitates from the spent liquor and can be recovered on a drum filter. The lignin cake can be washed on the drum filter with a shower of clean condensate obtained from the stillage evaporator, and then dried in a drier of appropriate design, before bagging and sale. This pure form of lignin has multiple high value uses including as an animal feed efficiency enhancer and as a natural antioxidant in rubber, oils and greases.

The liquor stream from the drum filter can be fed \\melb_files\homeS\Luisa\Keep\Speci\AU Process for treating biomass fibrous material Skrine.doc 8/08/00 6 to a distillation column for recovery of ethanol for recycle in the process. Because of normal process losses there is a need for make-up ethanol. In this invention the required make-up ethanol may be provided internally by first concentrating the distillation tower bottoms (stillage) in an evaporator. After decanting residual lignin and supplementing this liquor with nitrogen and phosphorus-rich effluent from the processing plant, together with waste sugar or starch, it can be fermented by either yeast or anaerobic bacteria to produce ethanol for process make-up or mixed solvents (butanol/acetone/ethanol). Xylose could be recovered from the concentrated stillage prior to this step. In the case of ethanol production the fermented broth can be filtered 15 and combined with the distillation feed stream from the lignin filter and ethanol co-recovered in the same tower.

S" The stillage from this recovery would be rich in acetic acid. Upon evaporation of this stillage an acetic acidrich condensate can be recovered which can be used partly for lignin washing and the remainder sent to acetic acid recovery. The output from this plant can be used partly to acidify the stillage for lignin precipitation and the remainder can be sold as food-grade acetic acid, or combined with the wet oxidation liquor for sale as sodium 25 acetate. Market conditions would determine the highest value use for this material. The solids separated from the fermented broth are rich in protein and minerals and could be a suitable animal feed supplement or be used as a fertiliser on the cane fields.

The distillation tower could recover not only ethanol for recycle, but also furfural and ethyl acetate, two valuable products that are generated during the bagasse cooking stage. Both can be sold, probably as crude products suitable for upgrading at a centralised facility.

Such activities would encourage the formation of additional local industries designed to support the sugar cane processors using the technology described in this \\melbfiles\home$\Luisa\Keep\Speci\AU Process for treating biomass fibrous material Skrine.doc 8/08/00 7 invention. Other local industries could take the lignin produced in these mills and convert it to value-added products, such as concrete admixtures and dye dispersants.

Other options presented by this invention include the recovery of xylose (a sugar present in large quantities, mostly as xylan, in bagasse). This could be sold in the world market for pure xylose that is used as a starting material in the production of the anti-caries sweetener, xylitol. Xylose can also be converted to furfural. If market prices support this option then xylose recovery could be maximised by extended steaming of the bagasse prior to cooking. Xylose would be recovered from the steaming condensate.

Utilising this option would lead to higher value 15 pulps because they would now have high alpha-cellulose content and therefore be suitable for rayon production.

The result for the sugar cane industry of practising this invention would be the elimination of costly environmental control operations and the production of significant 20 revenues from the sale of several value-added products.

These products would in turn create opportunities for the introduction of ancillary industries.

Description of the Drawing 25 In the accompanying drawing, which illustrates by way of example an embodiment of this invention, Fig.l is a flow diagram identifying the unit process steps of an integrated process for the production of pulp and several useful by-products from bagasse, a biomass residue of the sugar cane industry. While not every unit process is essential for the economic success of the invention, the combination of all these unit processes provides maximum utility of the invention.

Figure 1 depicts a rotatable spherical digester 1 connected by pipelines to a first liquor tank 2, a second liquor tank 3 and a spent liquor tank 4. The first liquor tank 2 and the second liquor tank 3 are also connected to a \\melbfiles\home$\Luisa\Keep\Speci\AU Process for treating biomass fibrous material Skrine.doc 8/08/00 8 fresh alcohol tank 5. The spent liquor tank 4 is connected to flash tank 6, which in turn is connected to lignin precipitation tank 7 by line 8, as well as to a recovered alcohol tank 9 by means of line 10. Digester 1 has a "top line" 45 and a "bottom" exit line 47. When rotated through 900 from the position depicted in Figure 1, the exit line is protected by screen 42. Bagasse from hopper 40 can be fed by conveyor 41 through a hatch in digester 1. Liquor from second liquor tank 3 may be pumped by pump 43 through heat exchanger 44 into digester 1 through line The lignin precipitation tank 7 is connected to a drum filter 11 by line 12. Mother liquor 13 can be pumped to distillation column 14 through line 15 by pump 16. The bottom of distillation column 14 is connected to the top of 15 the lignin precipitation tank 7 as well as an evaporator 19.

Vapour from the evaporator 19 is condensed by condenser 20 before passing to an acetic acid recovery unit 21. Underflow from the evaporator is led via line 22 to "20 decanter 23. The top of the decanter 23 is connected to a xylose recovery unit 24. Waste sugar from the xylose recovery unit is taken via line 25 to fermenters 26.

Detailed Description of the Preferred Embodiment 25 The present invention is directed at a single integrated process that converts biomass residues from the sugar cane industry, sometimes referred to as bagasse, into a series of valuable products including, but not limited to, papermaking pulps. The process is integrated with the element of fermentation of waste and low grade molasses to produce ethanol, other fermentation products and high protein animal feed. Other sources of low grade, but fermentable carbohydrate may be substituted for molasses in this invention. A key element incorporated into the process is organosolv delignification of bagasse. This element utilizes some of the alcohol generated in the fermentation element. The organosolv element generates products such as \\melb files\homeS\Luisa\Keep\Speci\AU Process for treating biomass fibrous material Skrine.doc 8/08/00 9 lignin, xylose, furfural, acetic acid and pulp for use in papermaking, dietary fibre, or as chemical cellulose. Much utility is gained by integrating these several elements into a single process. The advantages include heat and energy reduction through process integration, capital reduction through the co-processing of various process streams and waste minimization opportunities through the combining of several process streams. These elements and advantages are illustrated in the process flow diagram, Fig.l.

The process starts with the preparation of the bagasse into a form suitable for packing into a pressure vessel, identified in Fig. 1 as a digester 1. The preferred T f r form is stem sections of approximately ten centimeters in length, but any similar form is appropriate. A compressed pellet is also appropriate as feed for the digester 1. As illustrated the digester 1 is one of a series of batch digesters that may be rotating spheres, or a continuous conveyed inclined or horizontal tube configuration, but could also be a vertical tubular batch or continuous design. In Fig.l a preferred configuration of a rotating spherical batch digester 1 is illustrated. The operations described below for one digester are identical to those for the additional digesters that are operated sequentially at appropriate intervals to allow optimal use of the remaining equipment in the process.

Following preparation of the fibrous residue (bagasse) into the useful form described above it is conveyed by conveyor 41 to the top of the digester for loading into the digester. Once the digester is filled with a pre-determined amount of bagasse, the conveyer 41 is stopped and the digester is closed. An exhaust valve located behind a screen 42 in the bottom of the digester is now opened and low-pressure steam (less than 50 psi) is allowed to enter the top of the digester 1. This steaming, which is required to displace air in the fibre bed, continues until temperature sensors in the exhaust line \\melb_files\homeS\Luisa\Keep\Speci\AU Process for treating biomass fibrous material Skrine.doc 8/08/00 10 indicate that steam is exiting from the bottom of the digester 1. Any condensate of the steaming exits through the same line. Alternatively, if the moisture content of the bagasse is too high, nitrogen gas may be substituted for steam for the air displacement. All valves are now closed and the pump 43 in the line exiting the 2 d liquor tank 3 is turned on. The 2 nd liquor tank 3 is full of aqueous alcohol at the desired concentration and temperature. This liquor was used as a wash liquor from a previous digester cook and was retained between cooks in the 2 nd Liquor Tank 3. The preferred alcohol concentration in water is in the range of 35%-70% and the preferred temperature is in the range of 170 0 -205 0 C. This liquor is pumped through a heat exchanger 44 to maintain its desired o* 15 temperature and then into the top of the digester 1 through the top liquor line 45. Once the digester starts to fill, liquor exits the bottom of the digester from behind a screen 42 constructed around the outlet line at the bottom of the digester, from where it is returned to the top of the 2 nd Liquor Tank 3. This hot liquor circulation is continued for the appropriate time necessary to raise the contents of the digester to the desired cooking temperature. At this point the liquor exit valve 46 is closed and the desired weight of hot liquor, usually 2 to times the dry weight of the bagasse, is pumped into the digester from the 2 nd Liquor Tank 3. Liquor flow is then stopped, steam is continually sent to a jacket surrounding the digester to maintain its temperature at the desired cooking temperature and the spherical digester 1 is rotated for the desired cooking time. This time is normally between minutes and 3 hours, with the preferred time being between one and two hours. At the end of this time the rotation of the digester 1 is stopped with the liquor outlet line 47 and surrounding screen 42 at the bottom of the digester 1. Part of the hot black liquor is then flashed into a Flash Tank 6. The valve at the top of the 2 d Liquor Tank 3 is then closed and the return liquor is \\melbfiles\home$\Luisa\Keep\Speci\AU Process for treating biomass fibrous material Skrine.doc 8/08/00 11 diverted to the Spent Liquor Tank 4. Residual liquor in the 2 nd Liquor Tank 3 is pumped down to a level sufficient to keep the suction side of the pump 43 flooded. Liquor remaining in the Digester 1 is drained through the lower screens 42 into a drain line from where it is also pumped to the Spent Liquor Tank 4. Next, clean aqueous alcohol at the concentration and temperature previously described is pumped from the 1 st Liquor Tank 2 into the top 45 and bottom lines 47 of the Digester and returned to the 2 nd Liquor Tank 3 using the appropriate valves and pumps. After the 1 st Liquor Tank 2 has been almost emptied liquor flow to the Digester 1 is stopped and the remaining liquor in the Digester 1 is drained down and pumped to the 2 nd Liquor Tank 3 through the appropriate lines and valves. The o 15 Digester is now depressurized by opening the valves in the i top line 45 and the vapors passed to a Blow-Down Condenser 35. The alcohol-rich vapors are condensed and returned to the Recovery Alcohol Tank 9 for re-use in the process. The partially-delignified fibres are now sluiced from the 20 Digester 1 through the bottom valve, using water or preferably condensate from the evaporator. This sluiced pulp is sent to a tank 51 from which it is pumped continuously to conventional pulp refining 52, washing 53, screening, cleaning and bleaching operations. The liquor 25 from these operations can be processed by conventional means for alcohol recovery and sodium acetate recovery.

The spent liquor under pressure in the Spent Liquor Tank 4 is flashed into a Flash Tank 6 and the vapors condensed through the Blow-Down Condenser 35 and returned to the Recovery Alcohol Tank 9 for re-use. The condensed liquor in the Flash Tank 6, containing the extracted lignin, is then pumped to the Lignin Precipitation Tank 7 where it is mixed rapidly with stillage from the Distillation Tower 14 and the pH adjusted to below 3.0 with acid and the mixture cooled to about 17°. Lignin precipitates from the mixture and forms a slurry. This is pumped to a suitable filtering device, such as a drum \\melbfiles\homeS\Luisa\Keep\Speci\AU Process for treating biomass fibrous material Skrine.doc 8/08/00 12 filter 11, where the lignin is removed as a wet cake that is sent to an appropriate drier, while the filtrate is pumped to a Recovery Feed Tank 54. From this tank 54 the filtrate is pumped to an appropriately designed Distillation Tower 14. Such a tower would have a lower steam stripping section and an upper rectifying section, or be composed of two columns having these functions. In this tower alcohol, together with some esters, is recovered as an overhead condensate and returned to the Recovery Alcohol Tank 9 for re-use in the process. Furfural, which is present in the filtrate, accumulates at one of the lower trays in the rectifier section where it is drawn off, cooled and mixed with water before being sent to the Decanter 50. The lower liquid phase in the decanter is 15 crude furfural, which is up-graded to merchant furfural in a commercially available system. The upper layer is aqueous alcohol, which is passed back to the Distillation Tower 14 to recover the alcohol by mixing with the tower feed stream. Steam to power the stream stripping section is provided by Reboilers 36 at the bottom of the tower.

Aqueous stillage from the bottom of the Distillation Tower 14 containing sugars, some lignin and minerals, is sent to an appropriately designed multi-stage evaporator 19 where it is concentrated to about 25% solids.

25 This concentrate is pumped to an Evaporator Concentrate Decanter 23 where a lower layer of oily lignin is recovered and dried. The upper aqueous layer containing xylose, xylans, other sugars and minerals, is sent to a commercially available xylose recovery unit 24 for production of purified xylose. The effluents from this unit include waste hexose sugars, which are passed to the fermentation operations for alcohol production, and an aqueous solution of minerals, which are returned to the cane fields as fertilizer.

The aqueous condensate from the Evaporator 19 is passed to a commercially-available solvent extraction unit 21, such as those employing tri-octyl phosphine oxide, \\melb_files\homeS\Luisa\Keep\Speci\AU Process for treating biomass fibrous material Skrine.doc 8/08/00 13 (TOPO), for recovery of acetic acid, formic acid, furfural and ethanol as separate marketable products. The clean water that exits this unit is useful in the pulp washing and bleaching operations.

Molasses and/or preconcentrated sugar mill effluents is used as the fermentation raw material in a fermentation plant employing yeast to produce ethanol and other fermentation products. This medium may be supplemented with additional sugars from acid-hydrolysis products of waste cellulose, as required for maximum productivity. Additional minerals that may be required at this stage can be supplied from the waste liquor stream of the xylose recovery plant. After fermentation is complete in a sequential battery of batch Fermenters 26, the beer is pumped to a Filter 37 where yeast and other solids are removed and dried for sale as high-protein animal feed supplement. The clarified beer is then passed to the Recovery Feed Tank 54, mixed with the filtrate from the Lignin Recovery Filter and pumped to the Distillation Tower for recovery of ethanol and other components.

By this invention a range of valuable products is produced from the solid and liquid residues of the sugar cane industry.

In the figures, the numerals refer to the 25 following features: 9 ooooo9 9 9 9 *9999 .99.

1 Spherical digestor, 50m 3 2 1 s t liquor tank 3 2 nd liquor tank 4 Spent liquor tank Fresh alcohol tank 6 Flash tank 7 Lignin precipitation tank 8 Feed line 9 Recovered alcohol tank Feed line 11 Drum filter H:\susanp\keep\STAR POWER 51888-00 amended pgs.doc 9/12/04 14 .9 9@ 9 9 99 9 99 9 9 90* 9.9.

9 9 9 99 9 9 9 9 6999 9* 12 Feed line 13 Mother liquor 14 Distillation column Feed line 16 Pump 19 Evaporator Condenser 21 Acetic acid recovery unit 22 Feed line 23 Decanter 24 Xylose recovery unit Feed line 26 Fermenters 27 Blow tank 28 Spent alcohol tank 29 Dilute alcohol tank 30 Furfural 31 Formic acid 32 Acetic acid 33 Lignin recovery 34 Lignin to drier 35 Blow-down condenser 36 Reboilers 37 Filter 38 Distillation 39 Waste liquor Hopper 41 Conveyor 42 Screen 43 Pump 44 Heat Exchanger Top line 46 Liquor exit valve 47 Bottom exit line (liquor outlet line) 48 Solids to animal feed 49 Blend Tank H:\susanp\keep\STAR POWER 51888-00 amended pgs.doc 9/12/04 15 Decanter 51 Tank 52 Pulp to refining 53 Pulp washing 54 Recovery feed tank Molasses and/or preconcentrated sugar mill effluents In the claims which follow and in the preceding description of the invention, except where the context requires otherwise due to express language or necessary implication, the word "comprise" or variations such as "comprises" or "comprising" is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention.

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Claims (9)

1. A process for delignifying biomass fibrous material comprising: digesting biomass fibrous material in a liquor comprising a mixture of an alcohol selected from ethanol, methanol or both, and water at elevated temperature and pressure for a time sufficient to at least partially delignify the biomass fibrous material and form a pulp, separating spent liquor from the pulp, washing the pulp with a fresh mixture of alcohol and water, recovering the fresh mixture of alcohol and water 15 to be recycled as the liquor, reducing the pressure to cause alcohol and water ***remaining with the pulp to evaporate, recovering the pulp, reducing the pressure of the spent liquor to enable volatile material to evaporate thereby leaving a lignin-rich condensed liquor, diluting the condensed liquor with aqueous stillage lowering the pH of the condensed liquor to below 3 and cooling the condensed liquor to cause lignin to 25 precipitate from a mother liquor, separating lignin from the mother liquor, distilling the delignified mother liquor to recover alcohol and furfural therefrom leaving the aqueous stillage, allowing the aqueous stillage to settle removing oily and waxy substances from an upper layer of the aqueous stillage thereby leaving an aqueous layer containing xylose, xylan and other sugars, and fermenting the aqueous layer to produce ethanol.

2. A process according to claim 1, wherein the process includes the step of recovering lignin and other chemicals from the spent liquor. H:\susanp\keep\STAR POWER 51888-00 amended pqs.doc 9/12/04 17

3. A process according to claim 1 or claim 2, wherein the liquor is maintained at a temperature in a range from 170 to 205 0 C.

4. A process according to claim 3, wherein the pressure is maintained at a level sufficient to prevent the liquor from vapourising.

A process according to any one of claims 1 to 4, wherein the liquor contains alcohol in a range from 35% to by weight of the liquor.

6. A process according to any one of claims 1 to wherein the time lies in a range from 30 minutes to 3 hours.

7. A process according to claim 6, wherein the time lies in a range from 1 to 2 hours. 15

8. An integrated process for producing pulp and g ethanol from biomass, the process including the steps of: digesting biomass fibrous material in a liquor comprising a mixture of an alcohol and water to produce a pulp and spent liquor, separating pulp from the spent liquor, I recovering alcohol from the spent liquor, and •fermenting an extract from the spent liquor and/or effluent from upstream processing of the biomass to produce ethanol. 25

9. A process according to any one of claims 1 to 8, wherein the liquor comprises a mixture of ethanol, methanol and water. 1A process for producing pulp, ethanol and other useful products from biomass fibrous material substantially as hereinbefore described with reference to the accompanying figure. Dated this 9th day of December 2004 STAR POWER INTERNATIONAL HOLDINGS LTD. By their Patent Attorneys GRIFFITH HACK Fellows Institute of Patent and Trade Mark Attorneys of Australia H:\susanp\keep\STAR POWER 51888-00 amended pgs.doc 9/12/04