MXPA05004742A - Improvements relating to the removal of soluble components from tobacco material and apparatus therefor. - Google Patents

Abstract

A multi-stage tobacco extraction process for removal of soluble components from tobacco material, wherein the tobacco material is sequentially substantially submerged in a solvent within a series of extraction tanks, which tanks are each inclined at a negative angle to the horizontal. The present invention also provides extraction apparatus comprising a plurality of inclined extraction tanks.

Description

IMPROVEMENTS IN THE EXTRACTION OF SOLUBLE COMPONENTS PRESENT IN TOBACCO AND APPARATUS MATERIAL FOR THIS END FIELD OF THE INVENTION The present invention relates to a process for the extraction of soluble components of material present in tobacco and with an apparatus for this purpose.

BACKGROUND OF THE INVENTION Due to the existence of chemical differences between the grades and types of tobacco, for example the Virginia and Burley tobaccos, compositions or mixtures of various grades or types are needed in order to obtain a final tobacco blend with chemical compositions. and sensorially balanced for use in smoking articles, for example, in cigars. Certain grades or types of tobacco contain certain substances in amounts that exceed the desired levels, which makes it necessary to dilute the tobacco before using it in articles for smoking. Some sensory attributes are natural to, and specific to, certain types of tobacco in such a way that in some cases they become indispensable. The dilution of tobacco types can reduce the applicability or make the use of certain types of tobacco and / or tobacco grades inflexible. So far it has been proposed to extract several components of the tobacco material to obtain a product with altered chemical and physical characteristics. Products with altered physical characteristics usually require an additional processing step for the purpose of being usable in a smoking article, for example as a reconstituted tobacco product. In order to overcome the often costly need for an additional process of the physically altered tobacco material, several processes have been described in which a chemical alteration of the tobacco material is effected without significantly altering the physical characteristics thereof. It is proposed in US Pat. No. 5,360,022 that the water-soluble components be extracted from the tobacco material in a one-step process using a liquid solvent. The process uses a housing of a single extraction, in a configuration inclined with respect to the horizontal plane, in which the solvent and tobacco material flow in countercurrent within the housing. The extraction process requires that the tobacco material be removed from the solvent during the rotation of a screw conveyor located inside the housing, the screw conveyor can be operated in the front direction as well as in the reverse direction.

Extraction of the components of the tobacco material is facilitated by the operation of the screw conveyor alternately in the front direction as well as in the reverse direction while the tobacco is fed at the upstream end of the extraction housing and the solvent at the end downstream of the extraction housing. As would be apparent to one skilled in the art, removal of the tobacco material from the solvent by each rotation of the screw conveyor would prolong the total time taken to facilitate the extraction of the necessary components of the tobacco material. A prolonged extraction time is costly as well as laborious and ultimately affects the physical characteristics of the tobacco material by prolonged exposure to the solvent. U.S. Patent 5,791,353 discloses a method for denitrifying the vapor phase tobacco material using a pressurizing apparatus in which the single extraction extraction housing is placed in a configuration inclined with respect to the horizontal axis and comprises a conveyor screw that removes tobacco material from the solvent through each rotation thereof. An overpressure within the system reduces the extraction time, however it needs the use of a pressurization system and, therefore, the operating costs of the system are considerable. The present invention is based on the applicant's observation as to the importance that during the extraction of components of the tobacco material the residence time of the tobacco material in a solvent is minimized, in such a way that the characteristics of the tobacco material remain practically unaltered by the extraction process and that the necessary extraction efficiency of the process would use the minimum possible volume of solvent. As mentioned in this document, the necessary extraction efficiency must be interpreted as meaning that it is the proportion of a soluble component necessary to extract it from the tobacco material in order to obtain a tobacco product with the necessary chemical composition. It is an object of the present invention to provide efficient and commercially practical extraction of soluble components of tobacco material. It is another object of the present invention to provide a process and apparatus for the extraction of soluble components present in tobacco material thanks to which the environmental impact of the process is minimized by maximizing the efficiency of the use of the solvent during the process. It is even another objective of the present invention to provide a process for extracting soluble components from the tobacco material through which a chemically altered tobacco material is produced, this material having a greater flexibility in terms of its uses in mixed tobacco products, at the same time that the physical characteristics of the tobacco material remain practically unchanged by the process. The present invention provides a multi-step process for the extraction of soluble components present in tobacco material, wherein the tobacco material is practically and sequentially immersed in a solvent within a series of sloped extraction tanks. Preferably the tobacco material practically and sequentially is submerged in three extraction tanks. Preferably at each stage of the multi-stage process the tobacco material is fed into an additional extraction tank, each of these extraction tanks being practically filled with solvent. The tobacco material is preferably transported through each extraction tank from the upstream end to the downstream end thereof, while being substantially submerged in the solvent. The tobacco material is then removed from each extraction tank and subsequently fed to another extraction tank or extracted from the extraction apparatus. As stated in the foregoing, the tobacco material is practically and sequentially immersed in a solvent within a series of inclined extraction tanks, the passage of the tobacco material through the series of extraction tanks is carried out in a predetermined direction, i.e., from one end upstream to one end downstream of each tank. It is very preferable that the solvent is supplied sequentially to the series of extraction tanks in a direction opposite to that which carries the flow of tobacco material. Therefore, within the series of extraction tanks, the supply of tobacco material and solvent flow in countercurrent. Advantageously, within each extraction tank, the solvent and tobacco material flow in the same direction. Even more favorably, the solvent and tobacco material, within each extraction tank, flow from the upstream end to the downstream end of that tank. Consequently, the transport of tobacco material through the extraction tank is improved by the action of a recycling pump for the solvent. The recycling pump for the solvent can be operated to extract the solvent from the downstream end of the extraction tank via a recycling pipe, and to pump the solvent to the upstream end of the same extraction tank. The suction provided by the recycling pump for the solvent extracts the tobacco material through the extraction tank to the downstream end thereof. Preferably, the tobacco material that is extracted according to the process of the present invention, is fed continuously to a first extraction tank before experiencing a sequential extraction in the first, second and third (if any) tanks of extraction. Preferably, the solvent is fed continuously to the third extraction tank and is fed sequentially from the third extraction tank to the second extraction tank and then to the first extraction tank. It will be apparent to those skilled in the art that in the process of the present invention more than three extraction tanks may be employed, however, two extraction tanks may be sufficient. Preferably the residence time of the tobacco material in each extraction tank is between about 5 minutes and 15 minutes, more preferably between about 5 minutes and 10 minutes and even more preferably about 5 minutes. It will be clear to those skilled in the art that the residence time for the tobacco material in each extraction tank will depend on the tobacco material undergoing the extraction and the solvent used to extract the soluble components of this material. The residence time for the tobacco material in each tank will also depend on the extraction efficiency needed for the tobacco material. Preferably the temperature of the solvent in each extraction tank will be in the range of about 70 ° C to 95 ° C and even more preferably between about 80 ° C and 85 ° C. Heat exchangers can be used between the extraction tanks in order to maintain the temperature of the solvent. Heat exchangers can also be used in the solvent recycling piping of each extraction tank, in order to maintain the temperature of the solvent inside each extraction tank. Suitable solvents for use in the process of the present invention can be selected from the group consisting of water or alcohol; aqueous mixtures Those skilled in the art will know other suitable solvents.

The ratio of total mass flow rate of the tobacco material to the total mass flow rate of the solvent in the series of extraction tanks may be between approximately 1: 2 and 1:30 and preferably may be between about 1: 4 and 1:20 and even more preferably between about 1: 4 and 1:10. That is, for example, for each 1 specific weight of the tobacco material that enters tank 1, 10 specific weights of solvent enter the final tank in the series of tanks used in the process. The ratio of the total mass flow rate of the tobacco to the total mass flow rate of the solvent will depend on the physical characteristics required in the tobacco product that is produced by the extraction process, that is, the extraction efficiency needed of process. The tobacco material suitable for the process of the present invention can suitably be cut into lamellae, chips, powder or fine particles. Advantageously, when the tobacco material is in the form of chips, the chips have a particle size between about 22 mm (7/8 inches) and 51 mm (2 inches). The process of the present invention is particularly useful for the extraction of tobacco-specific nitrites, nitrates and nitrosamines (TSNA) from tobacco material. The present invention further provides an extraction apparatus consisting of a plurality of inclined extraction tanks, each extraction tank comprising an extraction housing, a transportation means, an inlet for the tobacco material and an outlet means, and an inlet for the solvent and a means of exit. Advantageously, the extraction apparatus comprises three extraction tanks. According to the claim, the extraction tanks are advantageously inclined at a negative angle with respect to the horizontal axis. As mentioned in this document, a negative angle with respect to the horizontal axis must be taken to mean that it is that end upstream of the extraction tank that is greater, relative to the ground, to the downstream end thereof. , so that the extraction tank is configured in a slope from its upstream end to its downstream end. Preferably, the extraction tank is inclined at a negative angle with respect to the horizontal axis to approximately 5o, and more preferably is at a negative angle of between approximately 3o and 4 ° with respect to the horizontal axis. Advantageously, the extraction housing is a substantially cylindrical hollow tube. Preferably, the transportation means is a screw conveyor. Alternatively, the conveying means may be a conveyor belt comprising a means for holding the tobacco material, for example fastening pins. Other suitable means of transportation will be of common use to those skilled in the art. Preferably, the transportation means is located within the extraction housing. Advantageously, the screw conveyor comprises fins. Preferably, the fins are placed to form a helical path on the screw conveyor. Preferably, the screw conveyor is axially aligned with the longitudinal axis of the extraction housing. More preferably, the screw conveyor is coaxially aligned with the longitudinal axis of the extraction housing. Preferably, the screw conveyor is mounted rotatably in the extraction housing and can be rotated by motor means operably attached the. Conveniently, the rotation speed of the screw conveyor is selected according to the desired residence time of the tobacco material in the extraction tank. An alternative means of transportation may be another that is not in axial alignment with the extraction housing. Alternative means of transportation, for example, it can be configured at an angle with respect to the longitudinal axis of the extraction housing. When the transportation means is configured at an angle with respect to the longitudinal axis of the extraction housing, the fins attached to the transportation means are configured to rotate within the extraction housing without any obstruction. The tobacco inlet means of each extraction tank is preferably a hopper and, alternatively, a conveyor belt, which, together with an opening in the extraction housing, allows the tobacco material to enter the extraction housing at the end. upstream of it. Each extraction tank comprises a tobacco outlet means at the downstream end thereof. Preferably, the tobacco outlet means comprises a drainage means, by means of which the tobacco material can be extracted from the extraction tank through the opening located in the tank.

Advantageously, the drain means is a drain screw. Preferably, the drain screw extends into a solvent tank with a drain means, which solvent tank with a drain means forms an integral part of the exhaust housing at the downstream end thereof. Preferably, the drain screw comprises a helical hollow screw (as illustrated in the WANGROUP brochure) that can be operated to extract tobacco from the extraction tank. More preferably, the drain screw has a hollow spiral configuration. Conveniently, the drain screw can be rotated by a drive means. Advantageously, the drain screw is configured at a positive angle with respect to the horizontal axis so that, during operation, excess solvent flows back into the extraction tank while the tobacco material is withdrawn from the tank. Preferably, the drain means can further comprise a press at one end thereof, the end of which is distant from the extraction housing, the press can be operated to extract excess solvent from the tobacco material. Preferably one or more of the extraction tanks comprises a drain means with a press at one end thereof. It is much more preferred that at least the final extraction tank comprises a drain means with a press at one end thereof. Preferably, each extraction tank is provided with a means for recycling the solvent. Conveniently, the solvent recycling means is a pump that can be operated to extract the solvent from the downstream end of the extraction tank via a recycling pipe, and to enter the solvent at the upstream end of the same tank. extraction. Each extraction tank comprises a solvent outlet means, which means is preferably configured in such a way that the solvent leaves the extraction housing from the solvent tank with drain screw. Even more preferably, the solvent outlet means leaves the extraction housing from an upper part of the solvent tank with drain screw. Advantageously, the solvent outlet medium of an extraction tank is connected to the solvent inlet medium of the preceding tank via a solvent pipe. Advantageously, the solvent comes from a solvent container, the solvent container contains solvent without other components dissolved therein. Conveniently, the solvent outlet means has a pump means operably attached thereto. Preferably, the solvent outlet medium of the first extraction tank is connected to a waste solvent treatment medium via a solvent pipe. It is much more preferable that heat exchangers are provided between the extraction tanks and between the solvent container and the solvent inlet medium of the final extraction tank. The heat exchangers can be operated to maintain the temperature of the solvent within the series of extraction tanks. Advantageously, the heat exchangers can be provided in the solvent recycle pipe of each of the extraction tanks, whereby the temperature of the solvent is maintained within each of the extraction tanks. From the above description it will be understood that within each extraction tank, the tobacco material and the solvent flow in the same direction from the upstream end of the extraction tank to the downstream end thereof. Still further, in the process of the present invention, it will be understood that the overall overall flow of tobacco material through the series of extraction tanks is in the frontal direction from the first forward extraction tank, while the flow General overall of the solvent through the series of extraction tanks is in the reverse direction, that is, from the last extraction tank towards the penultimate extraction tank or towards the first extraction tank. From the first extraction tank, the solvent can be transported to a waste treatment process where the soluble components can be extracted from the solvent and, if necessary, recycle the solvent to be used again in the extraction process . Within each of the extraction tanks, a partial equilibrium is allowed to form between the components in the tobacco material and the components thereof dissolved in the solvent within that tank. The residence time of the tobacco material in each of the extraction tanks, the temperature of the solvent and the ratio of total mass flow rate of the tobacco material to the total mass flow rate of the solvent in the series of tanks of extraction will affect the partial equilibrium, and consequently, the extraction efficiency of the process. The process parameters can be set to produce a tobacco product having the required chemical characteristics after extraction. The creation of a concentration gradient of the solvent extract within the series of extraction tanks facilitates the efficient use of the solvent to produce the extraction efficiency required for the process. The concentration of the solvent extract is higher in the first extraction tank and lower in the last extraction tank. In order that the present invention can be easily understood and carried out quickly, reference will now be made, by way of example, to the following examples and accompanying drawings, in which: BRIEF DESCRIPTION OF THE DRAWINGS OR FIGURES Figure 1 shows an extraction tank of the present invention in longitudinal cross-section, and Figure 2 shows a multi-stage extraction apparatus in accordance with an embodiment of the present invention.

DESCRIPTION OF XA INVENTION In both figures the common aspects in both Figure 1 and Figure 2 are denoted with the same reference numbers. Figure 1 relates to an extraction apparatus for use in a single stage of the process of the present invention. Each stage of the process employs a single extraction tank, in general terms denoted by the reference number (24). The extraction tank comprises an extraction housing (3), the extraction housing (3) is a hollow, almost cylindrical tube. A means of transportation (4) is located within the extraction housing (3). In this mode, the means of transportation is a screw conveyor (4). The screw conveyor (4) is aligned coaxially with the longitudinal axis of the extraction housing (3) and is placed inside the extraction housing (3) so that the conveyor (4) does not extend at the downstream end of the housing extraction (3). The screw conveyor (4) can be rotated by a drive means (not shown), for example a motor. The rotation speed of the screw conveyor (4) alternates to effect a change in the residence time of the tobacco material within the extraction housing (3). The screw conveyor (4) further comprises fins (5), these fins (5) are placed to form a helical path on the screw conveyor (4). The extraction tank further comprises a tobacco inlet means and a tobacco outlet means (2, 25). The tobacco inlet means (2) is a hopper (not shown) located at the upstream end of the extraction housing (3). The tobacco outlet means (25) is placed at the downstream end of the extraction housing (3). Figure 1 shows an embodiment of the invention in which the tobacco outlet means (25) is a drain screw. The drain screw extends towards the extraction housing (3), through an opening found therein, in a solvent tank (11) with a drain screw, the tank (11) forms an integral part of extraction housing (3) at the downstream end thereof. The drain screw comprises a housing (13) of the drain screw and a helical screw path (14) of the drain screw having a spiral configuration having a central bore (not shown) located below the longitudinal axis thereof. The drain screw can be rotated by a drive means (not shown), for example a motor. During the operation, the drain screw rotates and removes the tobacco material from the extraction housing (3), through an opening located in the screw, at the same time that the excess solvent drains through the central hole of the screw of drain in the solvent tank (11) with drain screw. The drain screw is configured in such a way that the solvent is allowed to drain into the central hole at any point along the length of the screw. The drain screw has a press (15) located at one end thereof, this end is distant from the extraction housing (3). The press (15) can be operated to extract the excess solvent from the tobacco material before the material is taken out of a first extraction tank (24), through tobacco outlet (16), and fed into another extraction tank (24) or, alternatively, it is removed from the extraction apparatus. The extraction tank (24) has a means of solvent inlet and a solvent outlet means (1, 12). The means of entry of the solvent (1) is a pipe that enters the extraction housing (3) at the upstream end thereof. The solvent outlet means (12) is a pipe that allows the solvent to exit the extraction housing (3) at the downstream end thereof. The solvent outlet means (12) is placed so that the solvent leaves the extraction housing (3) from the top of the solvent tank (11) with a drain screw. The solvent outlet means has a pump (18) for the solvent operably linked thereto. The extraction tank (24) may further comprise a sensor (17) of the temperature of the solvent and / or a sensor (10) of the level of the solvent. Figure 1 also shows a system for recycling the integral solvent with the extraction housing (3). A recycling pump (8) can be operated to extract the solvent, via a line of recycle tubing (7), from the downstream end of the extraction housing (3) and to return the solvent to the extraction housing (3) at the upstream end thereof via an inlet of the recycled solvent ( 6). A heat exchanger (9) is integral with the recycling line (7). The solvent passes through the heat exchanger (9) before returning to the extraction housing (3). Figure 2 shows a complete apparatus in accordance with one embodiment of the present invention. The apparatus comprises three extraction tanks (24), each of the extraction tanks (24) is shown in Figure 1. The extraction tanks (24) form a modular system and a person skilled in the art from the The above description will understand that alternative embodiments of the present invention may comprise two or more extraction tanks. In accordance with the embodiment shown in Figure 2, a first extraction tank (24) has a solvent inlet (1) which is connected by means of a solvent pipe (19) with the solvent outlet (12) of the second extraction tank (24). The second extraction tank (24) has a solvent inlet (1) which is connected by means of a solvent pipe (21) with the solvent outlet (12) of the third extraction tank. The third extraction tank (24) has a solvent inlet (23) that joins with a clean solvent container (not shown). The solvent outlet (12) from the first extraction tank (24) is joined with a waste treatment system (not shown). Optionally, the heat exchangers (20, 22) are provided between the first and second extraction tanks (24), and between the second and third extraction tanks (24), respectively. During the operation, the extraction apparatus is supplied with solvent from an external solvent container (not shown). The solvent is pumped into the third extraction tank (24), via the solvent inlet (23), and each of the extraction tanks (24) is filled with solvent until the sensors (10) of the solvent level in each of the extraction tanks (24) indicate that the solvent feed should cease. The sensors (17) of the temperature of the solvent in each of the extraction tanks monitor precisely the temperature of the solvent and that of the heat exchangers (20) and (22) to ensure that the solvent remains at the correct temperature for the removal. The solvent practically fills the extraction tanks in such a way that a large part of the transportation means is immersed in the solvent. Each of the extraction tanks (24) is tilted at a negative angle with respect to the horizontal axis, which ensures that approximately a quarter of the screw conveyor is free of solvent at the upstream end thereof. During the extraction process, the solvent is fed continuously to the extraction apparatus from the clean solvent container (not shown), via a heat exchanger (not shown), into the solvent inlet (23) of the third extraction tank (24). The solvent of the third extraction tank (24) is extracted therefrom via a solvent outlet (12) and is pumped via a solvent pipe (21), through a heat exchanger (22), to a solvent inlet (1) of the second extraction tank (24). The solvent of the second extraction tank (24) is pumped via a solvent pipe (19), via a heat exchanger (20), to the solvent inlet (1) of the first extraction tank. The solvent outlet from the first extraction tank (24) is pumped into a waste solvent treatment process (not shown). Therefore, the general flow direction of the solvent in the extraction apparatus is in the reverse direction. The recycling system internal for each of the extraction tanks (24) is activated with the use of a pump (8). The recycled solvent passes through a heat exchanger (9) in order that the temperature of the solvent remains constant inside each of the extraction tanks (24). The recycled solvent is then returned to the same extraction tank (24) from which it had been extracted via an inlet of the recycled solvent (6). The action of the recycling pump (8) can also be assisted in moving the tobacco material within each of the extraction tanks (24) in a frontal direction. The ratios of solvent inlet and outlet flow should be balanced in such a way that the levels of the solvent inside the extraction tanks (24) remain relatively constant during the extraction process. The solvent flow rate of the solvent in the extraction apparatus should be set to use the smallest volume of solvent required to achieve the desired extraction efficiency of the process. Optimally, the ratio of the mass flow rate of the tobacco material to the mass flow rate of the solvent within the extraction apparatus should be in the order of approximately 1: 8. The screw conveyors (4) and the drain screws (14) in each of the extraction tanks should be fixed at the desired speed of rotation. Optimally, the rotation speed of the screw conveyor (4) should be such that the tobacco material that is removed should remain in each extraction tank for a residence time of approximately 5 minutes. The tobacco material, with an appropriate particle size, is fed into the first extraction tank through a tobacco input means (2). When the tobacco material is in the form of tobacco chips, the appropriate particle size is between about 22 mm (7/8 inches) and 51 m (2 inches). The tobacco material initially floats on the surface of the solvent until it is forced to submerge in the solvent as the screw conveyor (4) rotates in a frontal direction. The negative angle with respect to the horizontal axis of the extraction tank (24) helps force the tobacco material to be submerged in the solvent. A negative angle of up to about 5 ° is optimal for tobacco material with a particle size of between about 22 mm (7/8 inches) and 51 mm (2 inches). The tobacco material is transported through the first extraction tank (24) by the action of the screw conveyor (24) until the extracted tobacco material is withdrawn from the solvent tank (11) with drain screw from the first tank. extraction by means of the drain screw (14). The excess solvent flows back to the solvent tank (11) with the drain screw via the central hole of the drain screw (14). Optionally a press (15) is attached to that end of the drain screw (14) that is located distant from the extraction housing (3). The press can be operated to extract the excess solvent from the tobacco material before the tobacco material is fed to the second extraction tank. The process described is repeated in the second and third extraction tanks. A press (15) attached to the drain screw (14) of the final extraction tank (24) can be operated to extract excess solvent from the tobacco material before the material leaves the extraction apparatus. The following example is provided for the purpose of further illustrating one embodiment of the invention but it is not to be considered as limiting the scope thereof.

Example 1 Initially, pieces of Burley-type tobacco are cut to obtain a particle size of between about 22 mm (7/8 inches) and 51 mm (2 inches). The moisture content of the chips, before extraction, is in the region of 12.8%. Hot water, which can be used as the solvent in the extraction process, is allowed to flood the extraction apparatus, the apparatus comprises 3 extraction tanks configured at a negative angle with respect to the horizontal axis of the 3rd. The water is heated to approximately 80 ° C before it enters the extraction apparatus, and the heat exchangers are calibrated to keep the water at the selected temperature. The mass flow ratios of the chips and water are set to maintain a ratio of chips: water of 1: 8 within the extraction apparatus. The rotation speed of each of the screw conveyors is set so that the residence time of the extraction is 5 minutes. Table 1 shows the results of the extraction of pieces of Burley-type tobacco via the process of the present invention, the process parameters are those of Example 1.

Table 2 shows the typical reduction of typical TSNA and nitrates resulting from the extraction of the Burley-type tobacco chips using the process of the present invention, the process parameters are described in Example 1.

TSNA Nitrates Snippets of TSNA (ppm) Nitrates after after snuff type before the la Burley to extraction extraction extraction extraction moisture content 4.2 ppm 0.11% of 12.8% 14.8 4.47% (-72%) (-98% )

Claims (42)

1. CLAIMS 1. A multi-stage process for the extraction of the soluble components of the tobacco material, wherein the tobacco material is practically sequentially immersed in a solvent within a series of inclined extraction tanks; and wherein this solvent is sequentially supplied to this series of extraction tanks in a direction opposite to that of the flow of this tobacco material. 2. A multi-stage process according to claim 1, wherein the tobacco material is substantially and sequentially immersed in three extraction tanks. 3. A multi-stage process according to claim 1 or claim 2, wherein each of these extraction tanks is practically filled with solvent. 4. A multi-stage process according to any of claims 1 to 3, wherein the tobacco material is transported through each of these extraction tanks from an upstream end to a downstream end of this extraction tank. A multi-stage process according to any of the preceding claims, wherein within each of these extraction tanks the solvent and the tobacco material flow in the same direction. 6. A multi-stage process according to claim 5, wherein this solvent and this tobacco material, within each extraction tank, flow from an upstream end to a downstream end of this extraction tank. A multi-stage process according to any of the preceding claims, wherein this tobacco material is fed continuously into a first extraction tank before undergoing a sequential extraction in this first extraction tank, a second extraction tank and optionally a third extraction tank. 8. A multi-stage process according to claim 7, wherein the solvent is fed continuously into this third extraction tank (if any) and fed sequentially from this third extraction tank into this second tank. extraction and in this first extraction tank. 9. A multi-stage process according to any of the preceding claims, wherein the residence time of this tobacco material in each of these extraction tanks is between about 5 minutes and 15 minutes. 10. A multi-stage process according to claim 9, wherein this residence time is between about 5 minutes and 10 minutes. 11. A multi-stage process according to claim 10, wherein this residence time is approximately 5 minutes. 12. A multi-stage process according to any of the preceding claims, wherein the temperature of the solvent in each of these extraction tanks is in the range of about 70 ° C to 95 ° C. 13. A multi-stage process according to claim 12, wherein this temperature of the solvent is between about 80 ° C and 85 ° C. 14. A multi-stage process according to any of the preceding claims, wherein this solvent is selected from the group consisting of water or mixtures of water: alcohol. A multi-stage process according to any of the preceding claims, wherein the ratio of total mass flow rate of the tobacco material to the total mass flow rate of the solvent is this series of extraction tanks is between approximately 1 : 2 and 1:30. 16. A multi-stage process according to claim 15, wherein this ratio is between about 1: 4 and 1:20. 17. A multi-stage process according to claim 16, wherein this ratio is between about 1: 4 and 1:10. 18. A multi-stage process according to any of the preceding claims, wherein this tobacco material is cut into lamellae, chips, powder or fine particles. 19. A multi-stage process according to claim 18, wherein when this tobacco material is in the form of chips, the chips have a particle size of between about 22 mm (7/8 inch) and 51 mm (2 inches). 20. An extraction apparatus comprising a plurality of inclined extraction tanks, wherein each of these extraction tanks is inclined at a negative angle with respect to the horizontal axis and each extraction tank comprises an extraction housing, a means of transportation, a means of entry of the tobacco material and a means of exit of the tobacco material and a means of entry of the solvent and a means of exit of the solvent. 21. An extraction apparatus according to claim 20, wherein said apparatus comprises three extraction tanks. 22. An extraction apparatus according to claim 21, wherein this angle is up to about 5o. 23. An extraction apparatus according to claim 22, wherein this angle is between about 3o and o. 24. An extraction apparatus according to any of claims 20 to 23, wherein said extraction housing is a hollow, substantially cylindrical tube. 25. An extraction apparatus according to any of claims 20 to 24, wherein this conveying means is a screw conveyor. 26. An extraction apparatus according to any of claims 20 to 24, wherein this conveying means is a conveyor belt, this conveyor comprises a means for holding the tobacco material. 27. An extraction apparatus according to any of claims 20 to 26, wherein this means of transportation is placed within the extraction housing. 28. An extraction apparatus according to claim 25, wherein said screw conveyor is axially aligned with the longitudinal axis of this extraction housing. 29. An extraction apparatus according to claim 25, wherein said screw conveyor is rotatably mounted in this extraction housing. 30. An extraction apparatus according to any of claims 20 to 29, wherein this means of entry of the tobacco is a hopper or a conveyor belt. 31. An extraction apparatus according to any of claims 20 to 30, wherein said tobacco outlet means is at a downstream end of this extraction tank. 32. An extraction apparatus according to claim 31, wherein said tobacco outlet means comprises a drain means, by means of which the tobacco is extracted from this extraction tank. 33. An extraction apparatus according to claim 32, wherein said drainage means is a drain screw. 34. An extraction apparatus according to claim 33, wherein this drain screw extends into a solvent tank with drainage means, this solvent tank with drainage means forms an integral part of this extraction housing at the current end down from this accommodation. 35. An extraction apparatus according to any of claims 33 and 34, wherein said drain screw comprises a helical hollow screw that can be operated to extract the tobacco from this extraction tank. 36. An extraction apparatus according to any of claims 33 to 35, wherein this drain screw is fixed at a positive angle with respect to the horizontal axis such that, during operation, the excess solvent flows back into this extraction tank while the tobacco material is extracted from this tank. 37. An extraction apparatus according to any of claims 32 to 36, wherein said drain means further comprises a press at one end thereof, this end is remote from this extraction housing. 38. An extraction apparatus according to any of claims 20 to 37, wherein each of these extraction tanks is supplied with a means for recycling the solvent. 39. An extraction apparatus according to any of claims 20 to 38, wherein each of these extraction tanks comprises a solvent outlet means, this means of exit of the solvent is located in such a way that the solvent leaves each extraction housing from the solvent tank with drain screw. 40. An extraction apparatus according to any of claims 20 to 39, wherein the solvent outlet means of an extraction tank is attached to the solvent inlet medium of the preceding tank via a solvent pipe. 41. An extraction apparatus practically as described above, with reference to Figures 1 and 2. 42. A multi-stage process practically as described above with reference to Example 1.