WO2010086698A1

WO2010086698A1 - Mixing device and related method for mixing or emulsifying at least two substances

Info

Publication number: WO2010086698A1
Application number: PCT/IB2009/055330
Authority: WO
Inventors: Marina Scremin
Original assignee: Marina Scremin
Priority date: 2009-01-29
Filing date: 2009-11-25
Publication date: 2010-08-05
Also published as: ITMI20090102A1

Abstract

A mixer comprises a mixing chamber (2), access ports (3) adapted to enable access to the mixing chamber and propulsion means (4) acting on the mixing chamber for moving a mixture M or at least two substances to be mixed inside it; the mixing chamber extends along an operating axis (2a) and comprises an elongating portion (2b) adapted to impart a deforming stretching in the direction of the operating axis along which the mixing chamber itself extends, to a flow of material F disposed inside the mixing chamber, and at least one stratifying portion (2c) connected without a break to the elongating portion and adapted to internally define a multi-layer accumulation of the material flow F coming out of the elongating portion.

Description

MIXING DEVICE AND RELATED METHOD FOR MIXING OR EMULSIFYING AT LEAST TWO SUBSTANCES

D e s c r i p t i o n

The present invention relates to a mixing device to be used (although not in a limiting sense) for mixing or emulsifying or, more generally, forming a colloidal solution (or still more generally forming any aggregation, solution, composition or mixture) between two or more components in a homogeneous or heterogeneous aggregation phase.

It is known that in different operating steps use of "fluid" or "powdered" products is made necessary, which products in fact, from a physico-chemical point of view, appear in the form of particular aggregations (or mixtures, or yet compounds) made up of two or more substances; these forms of aggregations can consist, by way of example, either of more or less homogeneous substances of granular and/or powdered materials or of aggregations of substances in different aggregation states (powders that are soluble or insoluble in liquids, mutually insoluble liquids which however can be finely emulsified with each other, and so on) .

In order to form these mixtures (or different aggregations, such as emulsions, gels or colloidal suspensions, depending on current requirements) it is therefore necessary to use suitable machines, exactly referred to as mixers, the function of which is to cause mutual and physical and/or chemical penetration of the two substances into each other; at the end of the operating cycle of a mixer, the obtained mixture is sent into a suitable container. Among the great number of different mixers of known type, relatively widespread is a construction architecture in which a mixing chamber is positioned horizontally to the ground and is fed from opposite sides through inlet ports mutually facing in the mixing chamber; by co-ordinated and cyclical thrust actions of the two substances through such inlet ports mixing in the chamber occurs.

This first type of structure however has some serious operating drawbacks; in fact, the particular positioning of the mixing chamber does not allow the air remaining in the chamber at the beginning of the operating cycle to efficiently escape; this air therefore will tend to take up room also inside the mixture being formed, thus altering homogeneity and reducing density of same.

The air left in the mixing chamber (or at all events introduced thereinto at the moment of admission of particular substances, because it is entrapped in the hollow spaces between the powder grains, for example) is then incorporated into the mixture M, constituting an element worsening the overall quality and purity of said mixture.

In addition, the pneumatic resistance of this residual air creates discontinuity in the movement of the substances to be mixed, through expansion and/or contraction in an unforeseeable manner; this creates an inconstant flow and brings to decay of the finished product, when the compound (gel or other) being prepared is to be forced to a high speed, for example. The problems connected with the presence of residual air therefore involve oversizing of the mixer, while at the same time making it necessary to provide various sealing means counteracting and controlling an uncontrolled air diffusion.

One alternative type of known mixers contemplates a "continuously working" operation, or in other words is not based on a movement cycle of the substances to be mixed within a closed volume; these mixers practically consist of an extruder, in the end portion of which a particular device is present which imparts a high turbulence to the outgoing fluid and/or divides it into threads which are then mixed again being oriented on "collision trajectories".

These devices however, although of simple general structure, are therefore bound up with the fact that the mixture must be necessarily obtained by a single passage of the substances through the extrusion head, and this involves serious limitations in terms of quality and homogeneity of the obtained mixture.

In fact, if on the one hand for maximising the efficiency of mixing in a single "passage" through the end portion of the extruder, very high delivery pressures are required to be used during working, on the other hand, these high delivery pressures cause too high shearing stresses in the flow of the substances to be mixed, giving rise to decay of these substances from the molecular point of view; this is undesirable both in "chemical" and in "physical" terms.

In more detail, from the "chemical" point of view it is in fact possible to notice that the mixtures thus obtained are damaged by a substantial impoverishment of their features or are subjected to a drastic drop in the homogeneity and/or density (to such an extent that they can take too liquid a consistency) ; at the same time, from the "physical" point of view it is possible to notice that the high delivery pressures, combined with inner geometries of the extrusion heads that are not always optimal or suitable for optimisation, lead to a high wear of the inner parts of the mixer itself, and at all events generate problems of accumulation and/or clogging of the material in the regions where the flow stagnates; as regards the last mentioned case, rather often sintering phenomena of the powders pressed through these mixers are created, and these phenomena lead to creation of practically irreversible clogging conditions .

Generally, mixers of known type are usually designed for treating a very limited number of substances, or in any case are not able to operate with a satisfactory flexibility in terms of variety of the substances to be used and/or of overall volumes of the obtainable mixture.

Nevertheless, the hitherto highlighted drawbacks have a further worsening factor if the substances to be treated are designed for very advanced or delicate applications or at all events substances having a very high cost (to be mentioned is for example the hyaluronic acid with a high purity degree, to be used in tissue reconstruction or also the polysaccharides or hydratable powers, maybe those of gelatine, compounds of the hyaluronic acid, alginates and polymers of various kinds, thermoplastic or not) ; these materials are to be prepared in the form of mixtures, typically turned into gel, having precise features, and the machines that must govern this preparation have to ensure a high product yield with an important elimination of waste products or of products remaining inside the machines (that are therefore to be ejected by "washing" ) .

In the light of the known art exemplified above, it is an aim of the present invention to make available a mixer capable of obviating the above mentioned drawbacks .

In particular, the present invention aims at conceiving a mixer that can offer high operating capabilities in terms of homogeneity and density of the obtainable mixture, eliminating all operating problems connected with the presence of residual air (or other undesirable substance) within the mixing chamber.

At the same time, the present invention aims at conceiving a mixer that can operate on a wide variety of substances and is able to generate a wide range of volumes of obtainable mixture in each operating cycle, while at the same time minimising possible waste or residues of unworked material or material that cannot be extracted from the machine at the end of the production cycle.

In addition, the present invention aims at providing a mixer having a high reliability and reduced costs for planning, installation and servicing.

The foregoing and further aims are achieved by a mixer in accordance with the present invention having the features set out in the appended claims and hereinafter illustrated in one embodiment thereof, given by way of non-limiting example, and in the accompanying drawings, in which :

- Fig. 1 is a scheme in section of a mixer according to the invention;

Figs. 2 to 9 show different steps of a first operating cycle to be carried out with the mixer seen in Fig. 1;

- Figs. 10 to 17 show different steps of a second operating cycle to be carried out with the mixer seen in Fig. 1; and - Fig. 18 is a scheme in section of an alternative embodiment of the mixer according to the invention.

With reference to the drawings, the mixer of the invention is generally identified with reference numeral 1 and substantially comprises at least one mixing chamber 2 which in turn has an operating volume adapted to contain at least two substances Sl and S2 to be mixed.

Depending on current requirements, the mixing chamber 2 can be provided with additional particular operating functions, for instance it can be interlocked with thermoregulation means for determining a given temperature and/or inner thermal energy condition; the mixing chamber 2 may also have at least one transparent portion to enable an operator/controller to visually evaluate the progress of the production cycle.

To the aims of the present invention, it is also possible to notice that this operating volume, in the course of the operating cycle of mixer 1, will also contain at least one mixture M exactly derived from the above mentioned substances to be mixed.

Also present is a given number of access ports 3 which are adapted to allow access to the mixing chamber 2, and simultaneously present are propulsion means 4 operatively acting on the mixing chamber 2 to move the mixture M or the at least two substances to be mixed Sl and/or S2.

Advantageously, the mixing chamber 2 extends along an operating axis 2a and comprises an elongating portion 2b adapted to impart a deforming stretching in the operating or axial direction 2a to a material flow F inside the mixing chamber (or at least in the running direction of the flow within the elongating portion 2b itself during the operating cycle of mixer 1) , and in succession also comprises at least one stratifying portion 2c which on the contrary is connected without a break to the elongating portion 2b and is adapted to internally define a multi-layer accumulation of the material flow F coming out of the elongating portion 2b.

For better explaining the structural and functional features of the present invention, it is at this point suitable to specify that the expression "material flow F" means a mass of material moving inside the mixer and more specifically inside the mixing chamber 2; conveniently, this mass at any "intermediate" moment of the operating cycle of mixer 1, will comprise the mixture M that has been already partly obtained and/or the substances to be mixed.

Still as regards the operating cycle of the present device, it is to be noted that the material flow F is cyclically and reversibly movable through the elongating portion and the stratifying portion; as a result of this, the present mixer differs from the "single passage" extruders described in connection with the known art, since the mixture M is obtained through several passages in a closed volume (the mixing chamber 2) which is then discharged, when appropriate.

Division of the mixing chamber into the two portions 2b and 2c mentioned above is designed to obtain a well precise state of efforts and deformation internal to the material flow F; actually, the elongating portion gives the material flow F a change in shape involving reduction of the passage section (and consequently, due to the constant volume, a longitudinal expansion and arising of forces of mutual penetration transverse to the flow direction) , the volume remaining constant, by virtue of which the substances will be forced to penetrate into each other thus carrying out a first mechanism promoting mixing.

Immediately after being "extruded" from the elongating portion 2b, the material flow F (that internally has generated the mentioned forces of mutual penetration) will be in a condition at which the viscous efforts generated inside it during its forcing through portion 2b will tend to have an effect from a kinematic point of view, giving rise to curves and bending in the flow itself; in addition, by its impacting against the walls confining the stratifying portion 2c, the material flow F will tend to gather upon itself, thus creating a three-dimensional accumulation of loops resting on each other (which can then collapse one after the other due to the intrinsic weight of the material itself) ; thus a further mixing mechanism is promoted that is amplified due to all possible ways in which the loops of the flow (that is continuous and substantially oriented in a single direction) coming out of portion 2b can approach or overlap each other in the space of the portion 2c itself.

It is finally to be noted that by virtue of the cyclical operation this three-dimensional accumulation, in which the degree of disorder is obviously greater than in the case of a "one-way" flow that has come out of the elongating portion 2b, will then be reintroduced into the elongating portion 2b itself and this will further promote mixing. In other words, it is possible to see that in the present invention the mixing chamber 2 first of all comprises an elongating portion adapted to impose isochoric deformations (i.e. of constant volume) and uniaxial deformations to the material flow F, and also comprises a stratifying portion 2c imposing substantially random and/or multi- ways spatial distortions to the material flow F; these distortions are carried out due to the action of the inner efforts accumulated/generated in the material flow F during its passage in the elongating portion 2b.

According to a further innovatory and original feature of the present invention, the mixing chamber 2 can advantageously comprise a collecting portion adapted to receive the material flow F by effect of the force of gravity, as well as a vent portion connected to the collecting portion and adapted to receive at least one foreign substance X relative to the substances to be mixed and/or to mixture M and/or relative to the material flow F.

From a structural point of view, this vent portion is connected without a break to the collecting portion and can take a position overlying the collecting portion. It should be pointed out that division of the mixing chamber 2 into a "collecting portion" and a "vent portion" as herein described (and claimed in the following) can also be independent of the division into an "elongating portion" and a "stratifying portion"; the choice of combining these pairs of functional features or not can be done based on current requirements, such as for instance the determination of a more or less high mixing/homogeneity degree and so on.

In other words, the present invention can also introduce (in a manner also independent of the above description) a particular division of the mixing chamber which is conveniently shaped for exploiting the effect of spontaneous separation between mixture M that will be obtained and one or more "foreign substances" (such as the residual air remaining within the mixing chamber at the beginning of the production cycle) that are characterised by having a smaller weight and/or density than the product-mixture M to be obtained: actually, due to the difference in the density and/or weight (or also in the specific weight) the present invention can advantageously provide a chamber in which the product-mixture M can be separated in ah autonomous and "automatic" manner from the undesirable substances at the end of the mixing process.

Turning back to the embodiment herein illustrated, and with reference to the drawings, it is possible to see at least two stratifying portions 2c which are connected to opposite ends of the elongating portion

2b; in this construction architecture the so-called

"collecting portion" is coincident with the stratifying portion in which the material flow F and/or the foreign substance X have a potential energy of a minimum value, while the so-called "vent portion" is coincident with the stratifying portion 2c (or also, depending on the spatial arrangement of the mixing chamber 2, with the elongating portion 2b or even with only part of the latter) in which the material flow F and/or the foreign substance X have a potential energy of a maximum value.

In addition, within the scope of the present invention, and taking into account the above discussed features, different spatial arrangements of the mixing chamber 2 are possible; for instance, the elongating portion 2b can be disposed in a vertical direction relative to the ground, while two stratifying portions 2c also disposed in a vertical direction are present and they are connected to opposite ends of the elongating portion

2b; in this case, the operating axis 2a is ideally defined by a continuous vertical straight segment passing through the stratifying portions 2c and the elongating portion 2b.

Alternatively, the elongating portion 2b can be disposed in a horizontal direction relative to the ground, while the two stratifying portions 2c are disposed in a vertical direction (and can protrude in the half-space above or under the lying plane containing the elongating portion 2b) , although they are always connected through suitable curved or angled connecting portions, to opposite ends of the elongating portion 2b; in this case, the operating axis 2a is defined by a broken line having two vertical end stretches passing through the stratifying portions 2c and a median horizontal stretch passing through the elongating portion 2b. Depending on current requirements, the elongating portion may also have developments different from the straight one; in fact provision can be made for a C- or V- or U-shaped development or a development in the form of a siphon with one or more curves, and so on.

Referring now to the functional concept of the "collecting portion", the latter can be defined as a portion of the mixing chamber 2 placed to a minimum height from the ground, while the "vent portion" is made up of a portion of the mixing chamber 2 placed to a maximum height from the ground.

In order to allow the beginning and end of the production cycle (and also for allowing the foreign substance X to be taken out at any moment of the production cycle) , charging and discharging means 5 can be present which is adapted to selectively determine entry and/or exit of the substances to be mixed and/or mixture M and/or the material flow F and/or the foreign substance X relative to the mixing chamber 2.

In more detail, the charging and discharging means 5 comprises a predetermined number of injectors 5a preferably placed at the opposite ends of the elongating portion 2b (but also, if necessary, in one or more of the stratifying portions 2c or even in the propulsion means 4) and a predetermined and corresponding number of closure members 5b that can be operatively activated on the respective injectors 5a so as to reversibly configure them between an access condition and an isolation condition relative to the mixing chamber 2.

As already mentioned above, the elongating portion 2b has a constant section extending along the operating axis 2a, while a typical conformation of the stratifying portion 2c is characterised by a varying development of its section along the operating axis 2a; in particular, in order to impart the torsional/curving effect to the material flow F coming out of the elongating portion 2b, at least one stratifying portion 2c has an increasing section on moving away from the elongating portion 2b (thus defining a conical or pyramidal three-dimensional shape the inner space of which allows formation and subsequent overlapping/accumulation of the above mentioned "loops") .

If a further increase in the working degree of mixture M is required, the presence of at least one turbulence- inducing element 6 can be advantageously provided, which element is inserted in the mixing chamber 2 and acts at least on the material flow F.

Depending on current requirements, different types and/or geometries can be adopted for the turbulence- inducing element 6: for instance, it can be connected in an irremovable manner to the mixing chamber 2 or it can be provided with a rotational and/or translational movement relative to said mixing chamber 2; at all events, irrespective of the structure or type of the turbulence-inducing element 6, it is useful to the aims of the present invention the fact that this device is adapted to impart a predetermined deforming state that is obtained by applying shearing stresses and/or speed and/or direction and/or acceleration variations to the material flow F.

Still depending on current requirements, the turbulence-inducing element 6 can be positioned anywhere; for instance, at least one turbulence- inducing element 6 can be placed between the elongating portion 2b and at least one stratifying portion 2c, so as to amplify the stirring-up effects on the material flow F.

Paying now particular attention to the propulsion means 4 it is possible to see that in the embodiment shown said means comprises a predetermined number of pushers 4a (and in particular one pusher 4a for each portion of the mixing chamber that can be defined as a "stratifying portion") acting by their movements in at least one stratifying portion 2c.

Conveniently, by giving the elements of the present invention suitable sizes and/or shapes, the propulsion means can also act in the elongating portion 2b or in both portions 2b and 2c of chamber 2; at all events, pushers 4a can be moved in the different portions of chamber 2 with a reciprocating motion.

With reference to the drawings, the propulsion means 4 comprises at least one pair of pushers 4a acting on the mixing chamber 2 in order to impose movement directions that can be alternately inverted to the flow material F and/or the foreign substance X; advantageously, these pushers 4a can be movable in mutual synchronism (and more particularly, they can be synchronised in such a manner that while one of them approaches the elongating portion 2c, the other moves away therefrom and vice versa) .

Obviously, the mutual synchronism between pushers 4c can also be eliminated, and they can move in a substantially autonomous and mutually independent manner; typically, the above described mutual synchronism can be implemented in the "central" steps of the production cycle when the material flow F is required to carry out different "passages" through the elongating portion 2b, while during a discharging step of chamber 2 it may be useful that both pushers 4a would simultaneously approach the elongating portion 2b; likewise, during a charging step of chamber 2, both pushers 4a could usefully carry out a simultaneous moving-apart movement.

For the sake of completeness, it is to be pointed out that the operating possibilities of the present invention can also contemplate displacement of only one of the two pushers 4a belonging to a given pair, while the other remains substantially immobile; in this regard Figs. 2 and 3 or also Figs. 12 and 13 can be taken as examples.

The separation efficiency already achieved between mixture M (under preparation) and the foreign substance X (be it residual air or any other substance the presence of which is undesirable in the final product) , thanks to the hitherto described features, can be further increased by means of a purification assembly 7 adapted to eliminate the foreign substance X from the mixing chamber 2 and/or the material flow F; it is to be pointed out that the purification or suction unit 7 is not only able to eliminate the foreign substance X that has carried out a spontaneous separation from the mixture M being formed, but is also capable of promoting egress and separation of the foreign substance X that remains entrapped into the material flow F; this removal mechanism can be conveniently based on different chemical or physical principles, depending on the nature and/or the aggregation state of the foreign substance X.

For instance, should the foreign substance X consist of air or a residual gaseous mixture M, this purification assembly 7 is advantageously adapted to create a predetermined (partial or full) vacuum degree in the mixing chamber; in this manner, not only the foreign substance X already accumulated in the "vent portion" is eliminated due to a pneumatic effect, but all possible micro-bubbles of air and/or gas entrapped in the material flow F are forced to expand and burst due to the difference in the static pressure that is formed around each "entrapped" micro-bubble, which will give rise to release of the foreign substance X that is sucked by the purification assembly 7.

In the above embodiment given by way of example the purification assembly 7 is preferably connected to at least one access port 3 and can be typically connected to the vent portion of the mixing chamber 2 in such a manner that it will act in that part of chamber 2 where accumulation of the foreign substance X already spontaneously separated from the material flow F during the operating cycle of mixer 1 is more likely to occur.

If the foreign substance X has a different aggregation state and/or different physico-chemical properties, it is possible to provide a purification assembly 7 utilising different principles; for instance, for eliminating magnetically permeable metal slags the purification assembly can comprise a series of magnetically active elements attracting these slags towards the outside of chamber 2, or for eliminating electrostatic charges the purification assembly can apply suitable electric fields and provide appropriate "earthing" circuits.

Note that the purification assembly 7 hitherto described can also be applied to other types of machines and/or mixers, irrespective of the structural features of the mixer of the present invention.

In the described embodiment it is possible to see that the mixing chamber 2 comprises different portions that in turn are defined by volumes fixed over time; however, always within the scope of the present invention, a mixer can be also defined in which the mixing chamber 2 comprises at least one portion (that could be an elongating portion and/or a stratifying portion, or yet the collecting portion and/or the vent portion) having a shape and/or volume varying over time.

In particular, as seen with reference to Fig. 18, in this embodiment a turbulence-inducing element 6 can be present which is slidable relative to the operating axis 2a; this turbulence-inducing element 6 therefore divides the overall volume of chamber 2 into at least one, and preferably two, stratifying portions 2c corresponding to the chamber parts disposed upstream or downstream of said element 6, while the elongating portion 2b is represented by, or at all events comprises, the inner passage section formed in the turbulence-inducing element 6 itself.

By suitably moving element 6, for instance through appropriate actuating means 6a (for instance, electromagnetic actuating means like those shown in Fig. 18, where a solenoid is placed externally around the mixing chamber 2 and by creation of a variable magnetic field moves the turbulence-inducing element 6 made of a magnetically permeable material) , a flow of material is created through said element 6 and simultaneously stratifying portions thereof of varying volume are defined.

By virtue of the above described structure it is then possible to carry out the appropriate operations for separating the foreign substance, either if this substance is separated spontaneously from the mixture and/or the material flow, or if it is forced to escape from the already formed mixture by effect of the purification assembly; it is also possible, through opening of one or more access ports 3, to discharge the material or mixture from chamber 2.

It is also an object of the present invention to provide an innovatory and original method of mixing at least two substances, comprising the following steps:

- providing at least one first substance Sl and at least one second substance S2;

- introducing the first and second substances Sl and S2 into a mixing chamber 2;

- defining a material flow F by carrying out a mixing and/or a penetration and/or an emulsion (or more generally any other physico-chemical process leading to mutual mixing between two substances) between the first substance Sl and the second substance S2; and

- discharging a mixture comprising such a material flow F from the mixing chamber 2.

Advantageously, the step of defining the material flow F comprises a sub-step of inducing an elongating deformation in the material flow F, and a subsequent sub-step of determining a multi-layer accumulation of the material flow F itself.

The high degree of mixing, homogeneity and density that can be obtained by the present method are advantageously usable in the production processes requiring high accuracy and in particular in the operating processes dealing with very expensive materials and/or materials requiring the greatest attention in order to avoid decay of the final product; it is for example possible that mixture M obtained by the method of the invention be a gel or similar colloidal solution or dispersion containing hyaluronic acid for medical use, or more generally at least one polysaccharide to be used in the branch of the so- called "tissue engineering" or at all events in the pharmaceutical/medical field.

In greater detail as regards the present method, the latter further comprises a step of spontaneously separating the material flow F and/or mixture M from a foreign substance X; this separating step in turn comprises a sub-step of spontaneously separating mixture M and/or the material flow F from the foreign substance X by effect of the force of gravity or more generally by effect of the different densities of mixture M and/or of the substances to be mixed, as compared with the density of the foreign substance X.

Conveniently, in the present method, the foreign substance X can be confined in a vent portion of the mixing chamber, and said foreign substance X can be subsequently discharged from the vent portion itself. Operatively and with reference to the features of mixer 1 as above described and hereinafter claimed, the operating steps illustrated above can be carried out by alternate, synchronised or autonomous, movements of at least one pusher and preferably with synchronised or autonomous alternate movements of two or more pushers exerting pumping and/or suction actions in the mixing chamber.

Advantageously, for further increasing the purity of the obtained mixture M, a step of separating a foreign substance X entrapped in mixture M or in the material flow F can be carried out; this step of releasing the entrapped foreign substance X is put into practice by the above described purification assembly.

In accordance with the invention and with reference to the seguences in Figs. 2 through 9 and 10 through 17, the present method can give rise to an operating cycle essentially consisting of the following steps:

- providing a first pusher 4a in a condition of maximum approach to one end of an elongating portion 2b of a mixing chamber 2 and simultaneously providing a second pusher 4a in a condition of maximum approach to an opposite end of the elongating portion 2b itself;

- introducing a first substance Sl into the mixing chamber 2 by moving a first pusher 4a away from the mixing chamber 2;

- compressing the first substance Sl by moving a second pusher 4a close to the mixing chamber 2 and simultaneously creating a vacuum through an access port 3 of the mixing chamber 2;

- introducing a second substance S2 into the mixing chamber 2 by moving the first pusher, as shown in Fig. 6 and/or the second pusher, as shown in Fig. 14, away from the mixing chamber 2;

- mixing the first and second substances, Sl and S2 by a predetermined number of simultaneous and co-ordinated movements designed to move the first and second pushers close to and away from the mixing chamber 2;

- accumulating a mixture M, preferably by effect of the force of gravity and/or in a manner co-ordinated with the movement of the first pusher 4a approaching the mixing chamber 2 and/or the movement of the second pusher 4b moving away from the mixing chamber 2, in a collecting portion of the mixing chamber 2 itself; and lastly

- discharging this mixture M from the mixing chamber through an access port 3.

Conveniently, during this operating cycle also provided can be a step of discharging, preferably through an access port 3, the foreign substance X that meanwhile may have already experienced a spontaneous separation from substances Sl and/or S2 and/or from mixture M and/or from the material flow F; for instance, this discharging step may take place simultaneously with the step of compressing the first substance Sl, as shown in Fig. 5 or in Fig. 13.

The above described operating cycle can be, in addition, integrated with the following sub-steps:

- subsequently to the step of providing the first pusher and the second pusher in said "condition of maximum approach to the mixing chamber 2", establishing a communication between the mixing chamber 2 and an external environment preferably by opening a first closure member 5b acting on an access port 3; typically a communication of a substance is established between the mixing chamber 2 and a holding tank; - subsequently to the step of introducing the first substance Sl into the mixing chamber 2, stopping the communication (of the substance) between the mixing chamber 2 and the external environment, i.e. the tank of the first substance Sl, preferably by closing the mentioned "first closure member 5b";

- subsequently to the step of compressing the first substance Sl, establishing a communication again between the mixing chamber 2 and an external environment that this time can be a tank for holding the second substance S2, preferably by opening the first closure member 5b again;

- subsequently to the step of introducing the second substance S2 into the mixing chamber, a communication between the mixing chamber 2 and the external environment is stopped again, preferably by a new closure of the first closure member; and

- subsequently to the step of accumulating mixture M, establishing a communication between the mixing chamber 2 and an external environment that in the last- mentioned case can be a "final" vessel for collecting the finished product, preferably by opening of a second closure member 6d acting on an access port 3 preferably placed at the collecting portion.

Conveniently, the method and the production cycle in accordance with the invention can be put into practice by a mixer 1 having one or more of the features included in those hereinbefore described and/or hereinafter claimed.

The invention enables important advantages to be achieved.

First of all, it will be appreciated that the particular construction architecture of this machine enables a substantially spontaneous elimination of the air, or more generally of any substance lighter than the substances that are to be mixed together, by utilising the effect of gravity and therefore obtaining an advantage correlated with the intrinsic simplicity of the structure itself.

It will be also recognised that the present mixer has the advantage, strictly correlated with the above listed one, of enabling highly homogeneous mixtures to be obtained that are also characterised by a high density.

Secondly, the present mixer allows a greatly efficient discharge of the mixing chamber to be achieved, thanks to which the obtained mixture M can be collected with the greatest accuracy, and when mixture M is drawn off the mixing chamber the occurrence of contaminations is avoided.

Moreover, the present mixer is able to implement particularly efficient production cycles, due to its structural and functional features allowing quick charging of the substances to be mixed, a mixing action as quick as the charging operation and a quick and practical step of preliminary preparation before starting a new production cycle.

Finally, it is to be noted that the present invention allows accomplishment of the machine being the subject matter of the invention itself with a high degree of reliability and repeatability and high operating flexibility, both in terms of substances that can be treated and of volumes of mixture M that can be produced, all that combined with low costs for production, validation of the process, cleaning/servicing and sale.

Claims

1. A mixer comprising:

- a mixing chamber (2) having an operating volume (2) adapted to contain at least two substances (Sl, S2) to be mixed and/or at least one mixture (M) derived from said substances to be mixed;

- a predetermined number of access ports (3) adapted to enable access to said mixing chamber (2); and - propulsion means (4) operatively acting on the mixing chamber (2) for moving said mixture (M) or said at least two substances to be mixed, characterised in that the mixing chamber (2) extends along an operating axis (2a) and comprises: - an elongating portion (2b) adapted to impart a deforming stretching in the direction of the operating axis (2a) to a flow of material (F) disposed inside the mixing chamber, said material flow (F) comprising the mixture (M) and/or the substances to be mixed; and - at least one stratifying portion (2c) connected without a break to the elongating portion (2b) and adapted to internally define a multi-layer accumulation of the material flow F coming out of the elongating portion (2b) .

2. A mixer as claimed in claim 1, wherein the material flow (F) is cyclically and reversibly movable through the elongating portion (2b) and the stratifying portion (2c) .

3. A mixer as claimed in claim 1 or 2, wherein the mixing chamber comprises a collecting portion adapted to receive at least the material flow (F) and/or the mixture (M) , by effect of the force of gravity; and - a vent portion connected to said collecting portion and adapted to receive at least one foreign substance

(X) relative to the substances to be mixed and/or relative to the mixture (M) and/or to the material flow

(F) , said vent portion being connected without a break to the collecting portion and being preferably placed in a position at which it overlies the collecting portion.

4. A mixer as claimed in claim 3, wherein at least two stratifying portions (2c) are present which are connected to opposite ends of the elongating portion (2b) , the collecting portion being coincident with at least one of said two stratifying portions (2c) and preferably being coincident with at least one stratifying portion (2c) in which the material flow (F) and/or the foreign substance (X) have a potential energy of a minimum value, the vent portion most preferably being coincident with at least one stratifying portion (2c) or with the elongating portion (2b) in which the material flow (F) and/or the foreign substance (X) have a potential energy of a maximum value .

5. A mixer as claimed in claim 4, wherein an elongating portion (2b) is present which is disposed in a vertical direction to the ground and wherein also present are two stratifying portions (2c) disposed in a vertical direction and connected to opposite ends of the elongating portion (2b) , the operating axis (2a) being defined by a continuous straight vertical segment passing through the stratifying portions (2c) and the elongating portion (2b) .

6. A mixer as claimed in claim 4, wherein an elongating portion (2b) is present which is disposed in a horizontal direction relative to the ground and wherein also present are two stratifying portions (2c) disposed in a vertical direction and connected, through connecting portions, to opposite ends of the elongating portion (2b) , the operating axis (2a) being defined by a broken line having two vertical end stretches passing through the stratifying portions (2c) and a horizontal median stretch passing through the elongating portion

(2b) .

7. A mixer as claimed in anyone of the preceding claims, wherein the collecting portion consists of a portion of the mixing chamber (2) placed to a minimum height from the ground, the vent portion being made up of a portion of the mixing chamber (2) placed to a maximum height from the ground.

8. A mixer as claimed in anyone of the preceding claims, wherein also present is charging and discharging means (5) adapted to selectively determine an entry and/or an exit of the substances to be mixed and/or the mixture (M) and/or the material flow (F) and/or the foreign substance (X) relative to the mixing chamber (2) .

9. A mixer as claimed in claim 8, wherein the charging and discharging means (5) comprises a predetermined number of injectors (5a) preferably placed at opposite ends of the elongating portion (2b) and a predetermined number of closure members (5b) that can be operatively activated on the respective injectors (5a) so as to reversibly configure them between an access condition and an isolation condition relative to the mixing chamber (2) .

10. A mixer as claimed in anyone of the preceding claims, wherein the elongating portion (2b) has a constant section extending along the operating axis (2a) , at least one stratifying portion (2c) having a varying, and preferably increasing, section extending away from the elongating portion (2b) .

11. A mixer as claimed in anyone of the preceding claims, wherein also present is a turbulence-inducing element (6) inserted in the mixing chamber (2) and acting at least on the material flow (F) , said turbulence-inducing element (6) being connected in an irremovable manner to, or being susceptible of movement relative to the mixing chamber (2) and being adapted to impart a predetermined deforming state that is obtained by applying shearing stresses and/or speed and/or direction and/or acceleration variations to the material flow F, the turbulence-inducing element (6) being preferably placeable between the elongating portion (2b) and at least one stratifying portion (2c) .

12. A mixer as claimed in anyone of the preceding claims, wherein the propulsion means (4) comprises a predetermined number of pushers (4a) movably acting in at least one stratifying portion (2c) and/or in the elongating portion (2b) with a reciprocating motion.

13. A mixer as claimed in claim 12, wherein the propulsion means (4) comprises at least one pair of pushers (4a) acting on the mixing chamber (2) to impose alternately reversible movement directions to the material flow (F) and/or the foreign substance (X) , said at least one pair of pushers (4a) preferably comprising pushers (4a) moving in mutual synchronism and/or co-ordination.

14. A mixer as claimed in anyone of the preceding claims, wherein also present is a purification assembly (7) adapted to eliminate the foreign substance (X) from the mixing chamber (2) and/or the material flow (F), said purification assembly (7) being preferably adapted to create a predetermined degree of vacuum (7) in the mixing chamber (2) .

15. A method of mixing at least two substances, comprising the steps of:

- providing at least one first substance (Sl) and at least one second substance (S2) ;

- introducing said first (Sl) and said second substance (S2) into a mixing chamber (2); - defining a material flow (F) by carrying out a mixing and/or a penetration and/or an emulsion between said first substance (Sl) and said second substance (S2); and

- discharging a mixture (M) comprising such a material flow (F) from the mixing chamber (2), characterised in that said step of defining a material flow (F) comprises a sub-step of inducing an elongating deformation in the material flow (F) , and a following sub-step of determining a multi-layer accumulation of the material flow (F) itself.

16. A method as claimed in claim 15, wherein also present is a step of spontaneously separating the material flow (F) and/or the mixture (M) from a foreign substance (X) , said step of separating the material flow (F) and/or the mixture (M) from said foreign substance (X) preferably comprising a sub-step of spontaneously separating the mixture (M) and/or the material flow (F) from the foreign substance (X) by effect of the force of gravity.

17. A method as claimed in claim 15 or 16, wherein also present is a step of separating a foreign substance (X) entrapped in the mixture (M) or in the material flow (F) .

18. A method as claimed in anyone of the preceding claims 15 to 17, wherein also present are the following sub-steps :

- providing a first pusher (4a) in a condition of maximum approach to one end of an elongating portion

(2b) of a mixing chamber (2) and simultaneously providing a second pusher (4a) in a condition of maximum approach to an opposite end of said elongating portion (2b) ; - introducing a first substance (Sl) into the mixing chamber (2) by moving a first pusher (4a) away from the mixing chamber (2) and/or by moving the second pusher

(4a) away from said chamber (2);

- compressing said first substance (Sl) by moving the second pusher (4a) close to the mixing chamber (2) and simultaneously creating a vacuum through an access port (3) of the mixing chamber (2);

- introducing a second substance (S2) into the mixing chamber (2) by moving the first pusher (4a) away from the mixing chamber (2) ;

- mixing the first and second substances (Sl and S2) by a predetermined number of simultaneous and co-ordinated movements designed to move the first and second pushers close to and away from the mixing chamber (2); - accumulating a mixture (M) , preferably by effect of the force of gravity and/or in a manner co-ordinated with the movement of the first pusher (4a) approaching the mixing chamber (2) and/or the movement of the second pusher (4b) moving away from the mixing chamber (2), in a collecting portion of the mixing chamber (2) itself ;

- discharging, preferably through an access port (3) , a foreign substance (X) spontaneously separated from the first and/or the second substances (Sl and/or S2) and/or from the mixture (M) and/or from the material flow (F) ; and

- discharging said mixture (M) from the mixing chamber through an access port (3) .

19. A method as claimed in claim 18, wherein also present are the following sub-steps: subsequently to the step of providing the first pusher and the second pusher in said condition of maximum approach to the mixing chamber (2), establishing a communication between the mixing chamber (2) and an external environment preferably by- opening a first closure member (5b) acting on an access port (3);

- subsequently to the step of introducing the first substance (Sl) into the mixing chamber (2), stopping a communication between the mixing chamber (2) and the external environment, preferably by closing said first closure member (5b) ;

- subsequently to the step of compressing the first substance (Sl), establishing a communication again between the mixing chamber (2) and an external environment preferably by opening the first closure member (5b) again;

- subsequently to the step of introducing the second substance (S2) into the mixing chamber (2), stopping again a communication between the mixing chamber (2) and the external environment, preferably by a new closure of the first closure member (5b); and

- subsequently to the step of accumulating the mixture (M) , establishing a communication between the mixing chamber (2) and an external environment, preferably by opening of a second closure member (6d) acting on an access port (3) placed at the collecting portion (4).

20. A method of mixing at least two substances, wherein one or more of the operating steps as claimed in anyone of the preceding claims 15 through 19 are carried out by a mixer (1) in accordance with anyone of the preceding claims 1 through 14.