AU732033B2 - Counter-current extractor - Google Patents

Description

WO 99/11349 PCT/AU98/00698 1 COUNTER-CURRENT EXTRACTOR This invention relates to a counter-current extractor for extracting an extract from a material to be extracted. The invention has particular application to producing an extract which has a desired aroma, colour or alcohol concentration, from grape fermented waste, which can be added back to wine to enhance the wine and increase the yield of wine from a particular volume of grapes.

However, the invention also has application generally in the food processing industry for extraction of liquids and fine solid particulate matter from associated solid material.

Counter-current extractors are well known and generally comprise an inclined elongate housing which may take the form of a trough or enclosed cylinder. The housing supports a screw conveyor and has an inlet for receiving material to be extracted and an outlet for discharge of solid material after extraction has taken place. The screw conveyor is arranged in the housing for conveying the material to be extracted from the inlet to the outlet. The housing is usually inclined so that the inlet is lowermost and a lower portion of. the housing defines a sump for the collection of extract. An extracting liquid inlet is provided in an upper portion of the housing for the supply of extracting liquid which flows downwardly in countercurrent to the material to be extracted so the extract will build up in the sump. The extract which builds up in the sump is drawn off from the sump and circulated back into the housing where it is sprayed onto solid material being extracted and which is being conveyed by the screw conveyor. Usually, the extract which is drawn off is heated before resupply to the housing takes place. The extract is circulated through the housing until the extract achieves the desired characteristics such as colour, aroma WO 99/11349 PCT/AU98/00698 2 or alcohol concentration and then may be drawn off from the sump.

The object of the present invention is to provide a counter-current extractor which improves the yield from the material to be extracted and which also may increase the quality of the extract which is produced.

The invention in a first aspect may be said to reside in a counter-current extractor for extracting an extract from a material being extracted, including: a housing having a feed inlet for receiving the material to be extracted and a discharge outlet for discharge of the material to be extracted after extraction has taken place, the housing including a sump region for collection of the extract; material moving means in the housing for moving the material from the inlet to the discharge; an outlet for the extract; a leaching fluid inlet for introduction of leaching fluid into the housing so that the leaching fluid can flow in counter-current with respect to the material being extracted; means for extracting vapour from the housing; and a condenser for condensing the vapour.

The means for extracting vapour enables volatile substances which are produced during the extraction process to be collected and condensed for future use. Such volatile substances include alcohol, essence and aromas produced during wine fermentation and which may be condensed and used as desired to increase the quality of the extract which is produced.

Preferably the housing is a substantially completely sealed housing so that vapour is not lost from the housing.

WO 99/11349 PCT/AU98/00698 3 Preferably the condenser is coupled to the outlet so that the condensed vapour is supplied to the outlet for mixing with extract drawn off through the outlet.

Preferably the means for extracting the vapour is a blower located in a conduit between the housing and the condenser for sucking vapour from the housing and supplying the vapour to the condenser.

Preferably extract collected in the sump is supplied to a separator for separation of a liquid phase from a solid phase.

Preferably the separator iscoupled to the housing for spraying the liquid phase back onto the extracting material so that fine particles in the liquid phase are filtered by the material being extracted as the material is moved by the moving means.

Preferably the separator is also coupled to the housing for the supply of the solid phase back to the housing onto the material being extracted as the material is moved from- the inlet to the discharge.

Preferably the separator comprises a hydro-cyclone.

Preferably the discharge is coupled to a press so that the material is supplied to the press from the discharge and is pressed to remove remaining excess liquid from the material after discharge.

Preferably the press is coupled to a tank for receiving the liquid produced by the press.

Preferably the tank is also coupled by a conduit to the housing so that liquid which drains from the material being extracted at the discharge end of the housing is supplied WO 99/11349 PCT/AU98/00698 4 to the tank.

Preferably the tank has an outlet which is coupled to the housing by a conduit for supplying liquid from the tank to the housing for spraying onto the material being extracted as the material moves from the inlet to the discharge.

Preferably the conduit which couples the tank to the housing supplies the liquid from the tank to the housing at a distance approximately 75% of the distance from the inlet to the discharge.

Preferably the sump is coupled to the separator by a conduit which includes a heat exchanger for-supplying-heat to the extract circulated from the sump-to the separator.

Preferably the extractor includes extract level control means for maintaining the liquid level in the sump substantially constant as extract is drawn off from the outlet by causing the leaching fluid inlet to open to supply additional leaching fluid to the housing.

A further aspect of the invention may be said to reside in a counter-current extractor for extracting an extract from a material being extracted, including: a housing having a fee& inlet for receiving the material to be extracted and a discharge outlet for discharge of the material to be extracted after extraction has taken place, the housing including a sump region for collection of the extract; material moving means in the housing for moving the material from the inlet to the discharge; an outlet for the extract; a leaching fluid inlet for introduction of leaching fluid into the housing so that the leaching fluid can flow in counter-current with respect to the material being extracted; and WO 99/11349 PCT/AU98/00698 5 a separator coupled to the sump for receiving extract from the sump and for separating a liquid phase in the extract from a solid phase in the extract and for supplying the liquid phase and solid phase separately back to the housing so that the solid phase is deposited on material being extracted as the material moves from the inlet to the discharge and the liquid phase is sprayed onto the material as the material moves from the inlet to the discharge.

This aspect of the invention enhances extraction by separating the solid and liquid phases of the extracted material and depositing the solid material back onto the material in the housing whilst spraying the liquid phase across the material as the material moves from the inlet to the discharge. Any fine particles in the liquid phase are effectively filtered by the material and therefore the amount of solid particles in the extract finally discharged through the outlet from the sump is reduced or controlled to a desired level.

Preferably the extractor includes means for extracting vapour from the housing and a condenser for condensing the vapour.

Preferably the housing is a substantially completely sealed housing so that vapour is not lost from the housing.

Preferably the condenser is coupled to the outlet so that the condensed vapour is supplied to the outlet for mixing with extract drawn off through the outlet.

Preferably the means for extracting the vapour is a blower located in a conduit between the housing and the condenser for sucking vapour from the housing and supplying the vapour to the condenser.

WO 99/11349 PCT/AU98/00698 6 Preferably the separator comprises a hydro-cyclone.

Preferably the discharge is coupled to a press so that the material is supplied to the press from the discharge and is pressed to remove remaining excess liquid from the material after discharge.

Preferably the press is coupled to a tank for receiving the liquid produced by the press.

Preferably the tank is also coupled by a conduit to the housing so that liquid which drains from the material being extracted at the discharge end of the housing is supplied to the tank.

Preferably the tank has an outlet which is coupled to the housing by a conduit. for supplying liquid. from. the. tank-to..

the housing for spraying onto the material being extracted as the material moves from the inlet to the discharge.

Preferably the conduit which couples the tank to the housing supplies the liquid from the tank to the housing- at a distance approximately 75% of the distance from the inlet to the discharge.

Preferably the sump is coupled to the separator by a conduit which includes a heat exchanger for supplying heat to the extract circulated from the sump to the separator.

Preferably the extractor includes extract level control means for maintaining the liquid level in the sump substantially constant as extract is drawn off from the outlet by causing the leaching fluid inlet to open to supply additional leaching fluid to the housing.

A third aspect of the invention may be said to reside in a counter-current extractor for extracting an extract from a WO 99/11349 PCT/AU98/00698 7 material being extracted, including: a housing having a feed inlet for receiving the material to be extracted and a discharge outlet for discharge of the material to be extracted after extraction has taken place, the housing including a sump region for collection of the extract; material moving means in the housing for moving the material from the inlet to the discharge; an outlet for the extract; a leaching fluid inlet for introduction of leaching fluid into the housing so that the leaching fluid can flow in counter-current with respect to the material being extracted; a press coupled to the discharge for receiving material which exits the discharge and for pressing the material to extract liquid remaining in the material; and a conduit between the press and the housing for supplying the liquid extracted by the press back to the..

housing.

The inclusion of the press removes additional liquid from the discharge material which would otherwise be wasted when the discharge material is discarded, and resupplies that liquid back to the housing to increase leaching of desired components from the material, thereby increasing the yield and quality of the extract.

Preferably the conduit between the press and the housing supplies the liquid into the housing and onto the material at a position about 75% of the way from the inlet to the discharge.

Preferably a pressed liquid tank is located in the conduit between the press and the housing for collection of the liquid from the press.

Preferably the housing includes an upper liquid outlet in WO 99/11349 PCT/AU98/00698 8 proximity to the discharge for collecting liquid from the material at the discharge end and for supplying the liquid to the pressed liquid tank.

Preferably extract collected in the sump is supplied to a separator for separation of a liquid phase from a solid phase.

Preferably the separator is coupled to the housing for spraying the liquid phase back onto the extracting material so that fine particles in the liquid phase are filtered by the material being extracted as the material is moved by the moving means.

Preferably the separator is also coupled to the housing for the supply of the solid phase back to the .housing onto the material being extracted- as- the- material is moved from the inlet to the discharge.

Preferably the separator comprises a hydro-cyclone.

Preferably the extractor includes means for drawing off vapour- from- the- housing and a condenser for condensing the vapour.

A further aspect of the invention may be said to reside in a press for removing liquid from a material, the press including: a first chamber; a plurality of outlet slots in the first chamber; a second chamber in communication with the first chamber; an outlet from the second chamber; closing means for partially closing the outlet from the second chamber; and pressing means in the first and second chambers for pressing material which enters the first chamber so WO 99/11349 PCT/AU98/00698 -9that the material is extruded out of the second chamber with the compression of the material causing liquid to be squeezed out of the material and exit the first chamber through the outlet slots.

Preferably the first chamber is surrounded by a collection chamber for collecting liquid which exits the first chamber through the outlet slots.

Preferably the pressing means comprises a screw conveyor for transferring material from an inlet end of the first chamber to the outlet of the second chamber so that material is compressed by the screw conveyor as it. moves from the inlet to the outlet and it is extruded from the outlet.

Preferably the closing means comprises a gate element which is movable to partially overlap the outlet to provide a reaction surface for- pressing- of- the -material whilst allowing the material to extrude through the partially blocked outlet.

Preferably a locating means is provided for locating the gate over the outlet.

Preferably the locating means comprises a screw member, ram or the like.

A preferred embodiment of the invention will be described, by way of example, with reference to the accompanying drawings in which: Figure 1 is a view of an extractor embodying the invention; Figure 2 is a view of a press used in the embodiment of Figure 1; and Figure 3 is a view along the line III-III of Figure 2.

WO 99/11349 PCT/AU98/00698 10 With reference to Figure 1, a counter-current extractor is shown which includes a housing 12 in the form of a closed cylinder or tube which, as is shown in Figure 1, is supported on an incline so a feed end 14 is lower than a discharge end 16. The housing 12 has a feed inlet 18 for receipt of solid material such as fermented grape waste which may include grape seeds, stalks and skin which are left after initial fermentation of grapes to produce wine.

The discharge end 16 includes a discharge tube 20 which is coupled to an integral press 22, which will be defined in more detail with reference to Figures 2 and 3. Arranged within the housing 12 is a screw conveyor 24 which is of known design and which is rotated by a motor 26 in a known manner. A perforated screen 28 is arranged at the feed end 14 and a second perforated screen 30 is also arranged at the discharge end 20. An outer sleeve 32 is arranged at the discharge end 16 around the perforated screen 30 for defining a discharge chamber 34 about the screen The inclination of the housing 12 (as is shown in Figure 1) defines a sump region 35 at the feed end 14 of the housing 12 for collection of extract. An outlet conduit 36 extends from the sump 35 within the screen 28 so that extract from the sump 35 can be drawn off from the outlet conduit 36.

The outlet conduit 36 is positioned part way up the sump as is shown in Figure 1 to allow clarified material with low suspended solids to be removed from the extractor. The outlet conduit 36 branches into an extract outlet conduit 38 which has a valve 40, and a recirculation conduit 42. A liquid level conduit 44 is also provided at the discharge end 14 and has a liquid level meter or device 46 for monitoring the liquid level in the sump 35. Solids which collected the bottom of the sump 35 can be discharged through the conduit 34 as needed.

The valve 40 and liquid level monitoring device 46 are WO 99/11349 PCT/AU98/00698 11 coupled to a controller 47 which monitors the flow rate of extract through the extract outlet valve 40 and also the liquid level in the sump 35 and provides a control feedback to a leaching liquid supply 48.

The leaching liquid supply 48 is coupled to upper discharge portion 16 of the housing 12 via conduit 50 for supply of leaching liquid to the housing 12. In the embodiment described which relates to the extraction of a wine extract, the leaching liquid is grape water which is a condensate taken from grapes during concentration during the wine making process to ensure that the extract produced by the counter-current extractor meets wine industry standards for use in the production of wine extract. In other embodiments, the leaching liquid supplied through the conduit 50 may be water or other leaching liquid suitable for the type of material being extracted.

As the liquid level in sump 35 changes due to extract being drawn- off through the outlet valve 40 or circulated through the circulation conduit 42, the feedback signal is supplied to the supply 48 to cause supply valve 52 to be opened so that the leaching liquid is supplied at the required rate to maintain the level in sump 35 substantially constant. A flow monitor 54 is also arranged in the conduit 50 for monitoring the flow rate of leaching liquid through the conduit 50 and an output is supplied to- the- valve- 5-2- forcontrolling the valve to set the require flow rate to maintain the level in the sump 35 substantially constant.

The circulation conduit 42 passes through a pair of heat exchange tubes 54 and 56 and then via conduit portion 42a of the conduit 48 to a hydro-cyclone 58. The heat exchange tubes 54 and 56 are coupled to a hot water circulation conduit 60, 62 and 64 so that hot water can flow through the conduit 64 from an inlet 63 through tube 56, conduit 62, tube 54 and conduit 60 back to the conduit 64 for WO 99/11349 PCT/AU98/00698 12 recirculation. Since the conduit 42 passes through the tubes 54 and 56 which have hot water running through them, heat exchange takes place with the extract in the recirculation conduit 42 to thereby heat the extract in the conduit 42.

Temperature of the hot water flowing through the tubes 54 and 56 is maintained at a desired temperature by heat exchanger 70 which is arranged on the conduit 64. The heat exchanger 70 includes a steam conduit 72 which passes through the exchanger 70 to a steam trap 74 to allow condensed steam to flow away. The steam flowing through the conduit 72 is controlled by a valve 76 which is coupled to a controller 78 which monitors the temperature of the hot water in the conduit 64 via a heat. sensor 78 to control the valve 76 to in turn control the amount of steam passing through the conduit 72 so that the hot water flowing through the conduit 64 is heated to the desired temperature to ensure that the extract flowing through the recirculation conduit 42 is heated to the desired temperature.

The hydro-cyclone 58 separates a liquid phase of the extract circulated through conduit 42 from a solid phase of that extract and supplies the liquid phase via conduit to a spray tube 82 arranged within the housing 12 above the material being moved and compressed by the screw conveyor 24 from the inlet 18 to the discharge 20. The tube 82 has a plurality of spray outlet nozzles 84 so the recirculated liquid phase is sprayed onto the material being compressed and conveyed from the inlet end 14 to the discharge end 16.

The liquid phase sprayed from the tube 82 by the nozzles 84 is sprayed over approximately two thirds of the length of the solid material being conveyed by the screw conveyor 24.

The solid phase separated in the hydro-cyclone 58 is supplied via valve 86 from the hydro-cyclone 58 back into WO 99/11349 PCT/AU98/00698 13 the housing 12 to deposit it on the material moving from the inlet end 14 to the discharge end 16. The discharge from the valve 86 takes place at determined time intervals and occurs approximately two thirds of the distance from the inlet 18 to the discharge Fine particles in the liquid phase which is resupplied to thehousing 12 via the conduit 80 and spray nozzles 84 are sprayed onto the material in the housing 12 being conveyed by the conveyor 24 and the material effectively acts as a filter for filtering out the fine particles to reduce the amount of solid matter in the extract in the sump The discharge material which exits the discharge chute and is supplied to the press 22 is pressed in the press 22 as will be described hereinafter so.that liquid remaining in the material is forced out of the material and collected via a conduit 88 for recirculation to the housing 12 through conduit portion 88a of the conduit 88.. The conduit 88 includes a liquor tank 90 for collection and storage of the liquid supplied from the press 22. The collection chamber 34 is also coupled to the tank 90 via a conduit 92 so that liquid which flows from the material at the discharge end 16 passes through the perforated screen into the chamber 34 and is supplied from chamber 34 via conduit 92 to the tank 90. The tank 90 has an outlet valve 94 arranged in the conduit portion 88a and a liquid level monitoring device 96 for controlling a flow valve 98 so as to control flow out of the tank 90 so that the liquid level in the tank 90 remains substantially constant and also ensures a continuous flow of liquid through the conduit portion 88a back to the housing 12. The tank 90 has an outlet valve 99 for draining of the tank 90 and cleaning of the tank when desired. The outlet 102 of the conduit 88 is preferably provided in the housing 12 a distance 75% of the way from the inlet 18 to the discharge 20 for resupply of the liquid from the tank 90 back onto the material being WO 99/11349 PCT/AU98/00698 14 conveyed from the conveyor screw 24 from the inlet 18 to the discharge An outlet conduit 110 is provided from the upper portion of discharge end 16 and is coupled to a blower 102 for extracting volatile material such as alcohol vapour from the housing 12. The blower 12 is coupled to a conduit 112 which passes through heat exchange tubes 114, 113 and 116.

The conduit 112 is coupled into outlet conduit 38 and recirculation conduit 42. Vapour which is sucked from the housing 12 by the blower 102 and supplied to the condenser 115 is condensed into a liquid such as alcohol and resupplied to the outlet 38 and recirculation conduit 42 via the conduit 112. In order to condense the vapour supplied from the blower 110, chilled water passes from an inlet conduit 118 into tube 116 via tube 120 into tube 113 via conduit 120 into tube 114 and out through outlet conduit 122 so as to cool the conduit 112 which passes through the tubes 114, 113 and 116 to effect heat exchange to cool the vapour and thereby condense the vapour into liquid form for resupply back to the conduits 38 and 42.

Liquid extract is allowed to circulate through conduit 42, having its solid and liquid phases separated by the hydrocyclone 58 and resupplied as described back into the housing 12 together with resupply of liquid through conduit 88a and condensed volatile vapour through conduit 112 until the extract in the sump 35 achieves the required characteristics such as aroma, colour or alcohol content.

Typically, the extract may be circulated in the above described way for half an hour or longer until the desired characteristics are achieved. The extract may then be drawn off through the outlet valve 40 for addition to partly process wine to enrich the colour and aroma of the wine whilst also increasing the volume of wine for a given volume of grape.

WO 99/11349 PCT/AU98/00698 15 Figures 2 and 3 show the press 22 in more detail. The press 22 has a first chamber 150 defined by a cylindrical wall 152. The first chamber 150 has an inlet end 154 which is in communication with discharge chute 20 from the housing 12. The cylindrical wall 152 has a plurality of narrow cuts or slots 156 within it to provide liquid outlets as will be described in more detail hereinafter.

An outer casing 158 surrounds the first chamber 150 and defines with the cylindrical wall 152 an outlet chamber 160. The outlet chamber 160 communicates with the conduit 88 for supply of liquid to the tank 90. The- first chamber 150 is coupled to a second chamber 170 which is defined by a solid cylindrical wall 172 and which has an outlet 174.

The cylindrical walls 152 and 172 which define the first chamber 150 and second chamber 170- may have end flanges 176 and 178 which are coupled together by bolts or the like (not shown) to couple the first chamber 150 in communication with the second chamber 170. In other embodiments, the second chamber 170 may-merely be a continuation or extension of the first chamber 150 defining a portion without the slots 154.

A screw conveyor 180 is arranged within the chambers 150 and 170 for moving material supplied from the discharge sheet 20 from the inlet 154 to the outlet 174. A gate 190is provided at the outlet 174 for partially blocking theoutlet 174. The gate 190 includes a plurality of slots 192 which receive pins 194 which project from a flange 196 at the outlet 174 so that the gate 190 can be moved to overlie the outlet 174. The gate 190 can be moved by a screw threaded shaft 198 controlled by a motor 199 or by any other suitable device such as a hydraulic or pneumatic ram or the like. Movement of the gate 190 is accommodated relative to pins 194 by the slots 192 in the gate 190.

As the material is conveyed by the screw threaded conveyor 180, the gate 190 provides an abutment surface so that WO 99/11349 PCT/AU98/00698 16 material is compressed as it is moved by the conveyor 180 from the inlet 154 to the outlet 174. The compression of the material causes liquid still remaining in the material to be squeezed out of the material and to exit the first chamber 150 through the cuts or slots 154 into the chamber 160 and then from the chamber 160 via conduit 88 into the tank 90. The material is extruded out of the restricted opening 174 in the form of a tightly compacted-mass for disposal.

The arrangement of the first and second chambers and the slots 154 in the first chamber have been found to provide a discharge for the liquid which is not blocked by thematerial as it is compressed within the press 20. The slots 154 also tend to be self-cleaning and non-clogging due to movement of material over the inner surface of wall 152. The arrangement also reduces the amount of solid material which is carried through the slots 154 with the pressed- liquid from the material within the chambers 150 and 170.

In the preferred embodiments of the invention, the speed of the screw conveyor 24 and also the conveyor 180 can be varied to suit the material being extracted and may also have a dwell period to also suit the specific requirements of the material being processed.

Since modifications within the spirit and scope of the invention may readily be effected by persons skilled within the art, it is to be understood that this invention is not limited to the particular embodiments described by way of example hereinabove.

Claims (36)

1. A counter-current extractor for extracting an extract from a material being extracted, including: a housing having a feed inlet for receiving the material to be extracted and a discharge outlet for discharge of the material to be extracted after extraction has taken place, the housing including a sump region for collection of the extract; material moving means in the housing for moving the material from the inlet to the discharge; an outlet for the extract; a leaching fluid inlet for introduction of leaching fluid into the housing so that the leaching fluid can flow in counter-current with respect to the material being extracted; means for extracting vapour from the housing; a condenser for condensing the vapour, the condenser being coupled to the outlet so that the condensed vapour is supplied to the outlet for mixing with extract drawn off through the outlet.

2. The extractor of claim 1, wherein the housing is a substantially completely sealed housing so that vapour is not lost from the housing.

3. The extractor of claim 1, wherein the means for extracting the vapour is a blower located in a conduit between the housing and the condenser for sucking vapour from the housing and supplying the vapour to the condenser.

4. The extractor of claim 1, wherein extract collected in the sump is supplied to a separator for separation of a liquid phase from a solid phase.

The extractor of claim 1, wherein the separator is coupled to the housing for spraying the liquid phase AMENDED SHEET I PR~/AUCl PCT/AU98/00698 Received 13 July 1999 18 back onto the extracting material so that fine particles in the liquid phase are filtered by the material being extracted as the material is moved by the moving means.

6. The extractor of claim 1, wherein the separator is also coupled to the housing for the supply of the solid phase back to the housing onto the material being extracted as the material is moved from the inlet to the discharge.

7. The extractor of claim 1, wherein the separator comprises a hydro-cyclone.

8. The extractor of claim 1, wherein the discharge is coupled to a press so that the material is supplied to the press from the discharge and is pressed to remove remaining excess liquid from the material after discharge.

9. The extractor of claim 1, wherein the press is coupled to a tank for receiving the liquid produced by the press.

The extractor of claim 9, wherein the tank is also coupled by a conduit to the housing so that liquid which drains from the material being extracted at the discharge end of the housing is supplied to the tank.

11. The extractor of claim 9, wherein the tank has an outlet which is coupled to the housing by a conduit for supplying liquid from the tank to the housing for spraying onto the material being extracted as the material moves from the inlet to the discharge.

12. The extractor of claim 11, wherein the conduit which couples the tank to the housing supplies the liquid from the tank to the housing at' a distance approximately of the distance from the inlet to the discharge. -4 -AMENE SHEET.. IPEA/AU PCT/AU98/00698 Received 13 July 1999 19

13. The extractor of claim 1, wherein the sump is coupled to the separator by a conduit which includes a heat exchanger for supplying heat to the extract circulated from the sump to the separator.

14. The extractor of claim 1, wherein the extractor includes extract level control means for maintaining the liquid level in the sump substantially constant as extract is drawn off from the outlet by causing the leaching fluid inlet to open to supply additional leaching fluid to the housing.

A counter-current extractor for extracting an extract from a material being extracted, including: a housing having a feed inlet for receiving the material to be extracted and a discharge outlet for discharge of the material to be extracted after extraction has taken place, the housing including a sump region for collection of the extract; material moving means in the housing for moving the material from the inlet to the discharge; an outlet for the extract; a leaching fluid inlet for introduction of leaching fluid into the housing so that the leaching fluid can flow in counter-current with respect to the material being extracted; and a separator coupled to the sump for receiving extract from the sump and for separating a liquid phase in the extract from a solid phase in the extract and for supplying the liquid phase and solid phase separately back to the housing so that the solid phase is deposited on material being extracted as the material moves from the inlet to the discharge and the liquid phase is sprayed onto the material as the material moves from the inlet to the discharge.

16. The extractor of claim 15, wherein the extractor includes means for extracting vapour from the housing and a -AMENDED SHE PCT/AU98/00698 Received 13 July 1999 20 condenser for condensing the vapour.

17. The extractor of claim 15, wherein the housing is a substantially completely sealed housing so that vapour is not lost from the housing.

18. The extractor of claim 15, wherein the condenser is coupled to the outlet so that the condensed vapour is supplied to the outlet for mixing with extract drawn off through the outlet.

19. The extractor of claim 11, wherein the means for extracting the vapour is a blower located in a conduit between the housing and the condenser for sucking vapour from the housing and supplying the vapour to the condenser.

The extractor of claim 15, wherein the separator comprises a hydro-cyclone.

21. The extractor of claim 15, wherein the discharge is coupled to a press so that the material is supplied to the press from the discharge and is pressed to remove remaining excess liquid from the material after discharge.

22. The extractor of claim 21, wherein the press is coupled to a tank for receiving the liquid produced by the press.

23. The extractor of claim 21, wherein the tank is also coupled by a conduit to the housing so that liquid which drains from the material being extracted at the discharge end of the housing is supplied to the tank.

24. The extractor of claim 22, wherein the tank has an outlet which is coupled to the housing by a conduit for supplying liquid from the tank to the housing for spraying onto the material being extracted as the material moves IPENAAU PCT/AU98/00698 Received 13 July 1999 21 from the inlet to the discharge.

The extractor of claim 24, wherein the conduit which couples the tank to the housing supplies the liquid from the tank to the housing at a distance approximately of the distance from the inlet to the discharge.

26. The extractor of claim 15, wherein the sump is coupled to the separator by a conduit which includes a heat exchanger for supplying heat to the extract circulated from the sump to the separator.

27. The extractor of claim 15, wherein the extractor includes extract level control means for maintaining the liquid level in the sump substantially constant as extract is drawn off from the outlet by causing the leaching fluid inlet to open to supply additional leaching fluid to the housing.

28. A counter-current extractor for extracting an extract from a material being extracted, including: a housing having a feed inlet for receiving the material to be extracted and a discharge outlet for discharge of the material to be extracted after extraction has taken place, the housing including a sump region for collection of the extract; material moving means in the housing for moving the material from the inlet to the discharge; an outlet for the extract; a leaching fluid inlet for introduction of leaching fluid into the housing so that the leaching fluid can flow in counter-current with respect to the material being extracted; a press coupled to the discharge for receiving material which exits the discharge and for pressing the material to extract liquid remaining in the material; and a conduit between the press and the housing for 4) S- AMENDED -SHEET-- IPEA/AU PCT/AU98/00698 Received 13 July 1999 22 supplying the liquid extracted by the press back to the housing.

29. The extractor of claim 28, wherein the conduit between the press and the housing supplies the liquid into the housing and onto the material at a position about of the way from the inlet to the discharge.

The extractor of claim 28, wherein a pressed liquid tank is located in the conduit between the press and the housing for collection of the liquid from the press.

31. The extractor of claim 28, wherein the housing includes an upper liquid outlet in proximity to the discharge for collecting liquid from the material at the discharge end and for supplying the liquid to the pressed liquid tank.

32. The extractor of claim 28, wherein extract collected in the sump is supplied to a separator for separation of a liquid phase from a solid phase.

33. The extractor of claim 28, wherein the separator is coupled to the housing for spraying the liquid phase back onto the extracting material so that fine particles in the liquid phase are filtered by the material being extracted as the material is moved by the moving means.

34. The extractor of claim 28, wherein the separator is also coupled to the housing for the supply of the solid phase back to the housing onto the material being extracted as the material is moved from the inlet to the discharge.

The extractor of claim 28, wherein the separator comprises a hydro-cyclone.

36. The extractor of claim 28, wherein the extractor AMENDED SHEET IPEA/AU PCT/AU98/00698 Received 13 July 1999 23 includes means for drawing off vapour from the housing and a condenser for condensing the vapour. AMENDED SHEET IPEA/AU