BE1021363B1 - PROJECTOR MACHINE. - Google Patents

Abstract

Spraying machine (1) comprising a mixing arm placed in a mixing chamber and extended by an eccentric screw (21) ending in a compression stage (11) of a pump, the pump being arranged to simultaneously pump a mixture to a mixing outlet (12) and to pump a solid phase to said mixing chamber (4), a control means (25) is connected to a rheological variable sensor of the mixture associated with a projection lance, and to a speed regulator arranged to act on said speed of rotation of the mixing arm.

Description

PROJECT MACHINE

The present invention relates to a device for spraying a mixture comprising a kneader provided with at least one liquid phase feed and at least one solid phase feed, said kneader having a kneading chamber, said kneading chamber comprising an output connected to an input of a compression stage of a pump, said compression stage comprising an output of said mixture connected to a first inlet of a projection lance arranged to project said mixture through a second orifice projection device in an external environment, said mixer comprising at least one rotary mixing arm passing through said mixing chamber, arranged to be set in motion at a rotation speed by a motor and for mixing said solid phase with said liquid phase to form a mixing mixture.

This device, known from FR2732263, comprises an inlet of said mixture provided by a piston pump, the mixture being pumped to a projection lance connected by one of its ends to the piston pump, to be then projected by a nozzle placed in the extension of a second end of the lance.

This device is used to apply a layer of a spray mix, particularly wet cement or tempered concrete, from a liquid phase and a solid phase.

The wet cement is first obtained conventionally in a mixer as described above, the output of the mixing chamber is connected to the compression stage of the piston pump.

However, such a mixer suffers from several pitfalls. On the one hand, in operation, it happens very often, for example on a site, that the liquid phase inlet flow, for example water, in the mixer and therefore in the mixing chamber varies over time . This variation may be due to the fact that the water supply to the mixer is connected to a common water intake from which another water supply is connected.

This variation in water flow affects the quality of the mixture to be sprayed. For example, if the water flow increases, the mixture formed is too liquid and does not stick, and, once projected, does not hold uniformly on the support, conversely, if the water flow decreases, the plaster formed is too thick and its projection is of lower quality since the projection of a mixture too thick compromises the uniformity of the mixture layer on the wall. On the other hand, the water flow rate may be low enough to obtain a mixture in the mixing chamber which has a high viscosity so that the rotational movement of the rotary arm is blocked at the compression chamber which can lead to a breakage of the latter which is always driven in a rotational movement. This risk is even higher than the mixture is characterized by a fast setting time. Generally, to overcome this problem, the known projection devices of the state of the art are provided with an emergency stop system for the rotation of the rotating arm, this system comprises a water flow sensor connected to a control means which controls the stopping of the rotation of the arm and therefore of the projection when the water flow passes under a predefined threshold value.

If this stop system makes it possible to block the projection in time to avoid a dramatic increase in the viscosity of the mixture to be sprayed, it is not a satisfactory alternative insofar as it involves a stop of the projection which compromises de facto the insurance to have an even layer of mixture.

To overcome these drawbacks, the device disclosed in the document FR2732263 comprises a flow control system in wet cement, fluidizing additive, and air which is provided by a system of flow sensors connected to a control panel.

In the device of the state of the art, the wet cement pumped from the mixer to the spray lance is mixed at the jet nozzle with a fluidizing additive and with compressed air, so that the mixture projected wet cement can achieve optimum quality, ie it has a viscosity that does not vary during the projection, and that its projection rate is constant so that its projection on a support, for example on a wall or on the walls of a tunnel, allows the formation of a layer of mixture as uniform as possible on the support.

In operation, the flow rate of fluidizing admixture in the pipe is measured and transmitted to a control panel and then compared to a threshold value. As soon as the adjuvant flow rate changes, a signal is emitted from the control panel to the wet cement pump motor and the compressed air pump motor with the appropriate pump flow rates.

Unfortunately, such a device suffers from several pitfalls. On the one hand, if the above-mentioned device makes it possible to correct the viscosity of the mixture which is produced at the outlet of the lance by injecting a fluidizing additive, it does not in any case make it possible to obtain a homogeneous projected mixture since no stage of mixing this additive with the tempered cement is provided in this device. On the other hand, if the device according to FR2732263 makes it possible to correct small differences in viscosity at the projection outlet, it nevertheless has a high degree of inertia insofar as a correction of the viscosity achieved at the outlet of the lance does not make it possible to maintain constant the rheological properties of the mixture when there is a large variation in the flow rate of arrival in the liquid phase or in the solid phase in the kneading chamber of the kneader.

So that the projection gives rise to the formation of a layer of mixing as uniform as possible on the support, the consistency of the projected mixture must be homogeneous and must not vary during the projection, it is also preferable that the mixture is projected at a constant projection rate. The aim of the invention is to overcome the disadvantages of the state of the art by providing a simpler construction projection device which makes it possible to guarantee a homogeneous and constant consistency of the mixture at the output of the mixer and at a constant or at least almost constant flow rate. during the projection process so that the projection of the mixture is as uniform as possible.

In order to overcome these drawbacks, provision is made according to the invention for a device as indicated at the beginning, characterized in that the said mixing arm is extended by an eccentric screw extending through the said outlet and ending in the said stage. compressing said pump, said pump being arranged for simultaneously pumping said mixture to said mixing outlet of said mixer and for pumping said solid phase to said mixing chamber, and in that it comprises a control means connected to a variable sensor rheological said mixture and a speed regulator of said engine, said sensor being associated with said spray lance of said mixture and said speed regulator being arranged to act on said speed of rotation of the mixing arm, said control means being arranged to receive a signal transmitted by the variable sensor and sending a signal to said controller based on a measured value by the sensor.

In this way, the consistency of the mixture is determined at any time during the projection by measuring a rheological variable value which is transmitted to the control means in the form of a signal. If this measured rheological variable value differs from a predetermined threshold value corresponding to a desired mixing consistency, the control means in turn sends a signal to the regulator which changes the rotational speed of the arm until the mixture at the end of mixing has the desired consistency.

Thus, unlike the device of the state of the art, the projection device according to the invention allows a correction of the consistency of the mixture carried out either after the mixture has been formed but rather during the formation of the mixture by mixing, which makes it possible, on the one hand, to have a device that is more responsive to variations in flow rates in the liquid phase or in the solid phase and whose regulation is simpler because it involves the use of only one sensor at level of the projection lance.

The present invention is based on the surprising effect that the modification of the speed of rotation of the kneading arm makes it possible to maintain a homogeneous and constant consistency over time while not affecting, or at least affecting, only very little, the output flow of the mixture so that the projection of the mixture is as uniform as possible.

Advantageously, said control means is a proportional-integral-derivative type corrector.

This type of regulator has the advantage of being easy to implement physically and can therefore be applied to regulate a device already in production. It also makes it possible to adapt the regulation to the evolution of parameters such as wear of the parts of the device, such as the rotor and the stator, or even the increase of the temperature in the compression stage.

In addition, in a particular embodiment, said regulator is a frequency converter and the motor is an AC motor.

In a particular embodiment, the sensor is a pressure sensor, preferably a strain gauge.

Preferably, said liquid phase comprises water.

Advantageously, said solid phase is a pulverulent inorganic material, in particular hydraulic material, preferably comprising at least one element chosen from the group consisting of gypsum, sand and dry cement.

In a particularly advantageous embodiment of the device according to the invention, said liquid phase supply is located at a level lower than that of said solid phase supply.

In this way, the compression stage and a lower part of the mixing chamber are constantly saturated with water so that, during mixing and pumping of the mixture, there is no formation of lumps or bubbles. air in the mixture. Other embodiments of the device according to the invention are indicated in the appended claims. The invention also relates to a method comprising the preparation of a mixture of a solid phase or of a pasty phase with a liquid phase, comprising: a supply of a liquid phase at a first flow rate in a chamber of kneading a rotary kneader, - supplying a solid phase at a second flow rate into said kneading chamber of said rotary kneader, - rotating kneading in said kneading chamber of said solid phase with said liquid phase to form a mixture of kneading by a kneading arm passing through said kneading chamber and arranged to be moved at a rotational speed by a motor; - pumping said mixture at a third pumping rate to a mixing outlet of said kneader connected to a first orifice input of a projection lance; projection of said mixture by a second projection orifice of said projection lance traversed by said mixture originating from said mixing output, - a measure of at least one rheological variable of said mixture, preferably the pressure, giving a first rheological variable value which is encoded as a first signal, - a reception of said first signal by a generating control means a second output signal to a speed controller of said rotary motor.

This method is characterized in that said kneading arm passing through said kneading chamber is extended in a compression stage of a pump where said step of pumping said mixture takes place, said kneading arm controlling said second delivery flow of said kneading chamber. solid phase to said mixing chamber and said third pumping rate of said mixture, and in that the step of measuring said rheological variable is performed at said projection lance, said speed regulator processing said second output signal for then controlling said motor rotating said kneading arm and regulating said rotational speed of said kneading arm and inducing a variation simultaneously of said second feed rate of said solid phase and said third pumping rate of said mixture.

In particular, this method further comprises a first comparison step in which said first signal is compared with a first reference signal corresponding to a second reference rheological variable value with the aid of a first comparison calculator of said first reference signal. control inputting said first signal and said first reference signal to output said second signal and send it to said speed controller.

Preferably, said second signal corresponds to a difference calculated between, on the one hand, said first rheological variable value and, on the other hand, said second reference rheological variable value, said second signal being processed at the input of said regulator of the rheological variable. a speed which decodes said second signal and translates it into an output simultaneously a variation of said second feed rate of said solid phase and said third flow rate of said mixture.

Advantageously, the step of processing said second signal by said speed controller is a proportional-integral-derivative type regulation step.

Optionally, said variation of said second feed rate of said solid phase and said third pumping rate of said mixture is carried out until said at least one rheological variable reaches a predetermined value.

In particular, said at least one rheological variable of said mixture is the pressure. Other embodiments of the process according to the invention are indicated in the appended claims. Other features, details and advantages of the invention will become apparent from the description given below, without limitation and with reference to the accompanying drawings.

Figure 1 schematically shows the projection device according to the present invention.

This device is particularly intended to form a mixture, for example plaster, from a liquid phase, for example water, and a solid phase, for example gypsum, and to project this mixture so as to form an even layer of this mixture for example on a wall.

Preferably, the liquid phase is water and the solid phase is a pulverulent mineral material, in particular hydraulic, preferably comprising at least one element selected from the group of gypsum, sand, dry cement.

In a preferred embodiment of the device according to the invention, the kneader may be fed with a pasty phase instead of a solid phase, the pasty phase is a moist mineral material comprising at least one element selected from the group of cement damp, slaked lime, and mortar.

Preferably, said mixture has a liquid phase: solid phase ratio of between 0.3 and 1, preferably between 0.4 and 0.8, advantageously between 0.5 and 0.7.

As can be seen in FIG. 1, the projection device 1 of a mixture comprises a kneader 2 divided into a lower part corresponding to a kneading chamber 4 and an upper part 3 situated above the kneading chamber 4 and traversed by an inlet for a solid phase 5, connected to a first solid phase feed 6, and an inlet for a liquid phase 7 connected to a second liquid phase feed 8, the orifice the inlet of the liquid phase 7 being placed at a level lower than that of the inlet of the solid phase 5. Each of the feeds 6, 8 may optionally be connected to a container 9 which may be a hopper 9 or a tank 9 '.

Said mixing chamber 4 is traversed by a first mixing outlet orifice 10 connected to a compression stage of a pump 11 provided with a second mixing outlet orifice 12 connected to an inlet port 13 of a lance 14 of projection. This lance is arranged to project the mixture from a second outlet orifice 15 connected to a projection nozzle 16 on a wall 17.

The kneader 2 is provided with a rotary kneading arm 18 arranged to pass through the upper part 3 and the kneading chamber 4, said kneading arm possibly being provided with one or more blades 19 and extended at a first end. 20, facing the mixing outlet port 10, by an eccentric "pigtail" screw 21 which extends through the mixing outlet port 10 to terminate in the compression stage 11 of the pump and form a Sparrow type pump comprising a rotor which is the eccentric screw and a stator which is the compression stage.

When the rotor is inserted into the stator, a double chain of sealed cavities (also called "cells") to the volume defined by the dimensions and shapes of the rotor and the stator is formed. When the rotor rotates inside the stator, the cells progress along the axis of rotation of the eccentric screw of the pump, which transfers the pumped mixture from the outlet of the mixing chamber of the pump to the outlet of the mixture.

The stator may comprise an inner wall coated with a rubberized material, this pump being arranged to simultaneously pump the solid phase from the upper part 3 to the mixing chamber 4, and the mixing of the mixing chamber to the orifice input 13 of the projection lance 14.

The rotary kneading arm 18 is connected by a second end 22, opposite to the first end 20, to a motor 23 arranged to rotate the rotary arm at a rotational speed along an axis of rotation r passing through the ends 20 and 22 of the arm.

The arm, once rotated, kneads the solid phase with the liquid phase to form the mixture.

The lance 14 of the projection device is associated with a rheological variable sensor 24 chosen from the following rheological variables of the mixture: pressure, viscosity, density, and stress. Preferably, the sensor is a strain gauge measuring the pressure of the mixture at the mixing outlet.

The device further comprises a control means 25, preferably a proportional-integral-derivative type calculator, connected by a first transmission line 11 to the sensor 24 and by a second transmission line 12 to a speed regulator 26 of the engine 23, this regulator is arranged to act on the speed of rotation of the mixing arm 18 on the basis of a value of the rheological variable measured by the sensor 24.

The control means is arranged to receive a first signal S1 emitted by the sensor 24 and send a second signal S2 to the speed regulator arranged to act on the speed of the motor via an actuator A which may be for example an inverter when said regulator 26 is a frequency converter and when the motor is an AC motor.

In operation and with reference to FIG. 1, the liquid phase is brought to a first fixed flow D1 from the upper part 3 to the mixing chamber 4 of the rotary kneader 2. The solid phase is brought to a second flow D2, which can be fixed or variable, from the upper part 3 to the mixing chamber 4.

The solid phase is conveyed at a flow rate D3 from a first container 9 to the upper part 3 of the kneader, while the liquid phase is conveyed at a flow rate D4 from a second container 9 'to the upper part 3 of the kneader.

The mixture is then formed by rotary kneading in the mixing chamber 4 of the liquid phase and the solid phase by the kneading arm 18 passing through this chamber and rotated at a speed of rotation by the motor 23.

Ideally, this mixture has a liquid phase: solid phase ratio between 0.3 and 1, preferably between 0.4 and 0.8, advantageously between 0.5 and 0.7.

The mixture is then driven, by the rotational movement of the eccentric screw of the rotary arm in the compression stage 11, from the mixing chamber 4 to the inlet port of the projection lance 14, and passes through the compression stage of the Moineau 11 pump which pumps the mixture to a pumping rate D5.

The mixture, driven to the pumping rate D5, passes through the lance 14 to reach the projection nozzle 16 and be projected on the wall. The pumping rate D5 must be determined as a function of the length L of the lance measured between the inlet orifice 13 and the outlet orifice 15.

Indeed, the longer the length L is, the greater the pumping rate D5 required to project the mixture so as to obtain a uniform layer must be high and therefore higher must be the speed of rotation of the rotary arm.

In stationary mode operation, that is to say at a speed in which the speed of rotation of the rotary arm is constant and in which the feed rates of the liquid phase D1 and the liquid phase D2 to the chamber of mixing, the flow rates of the liquid phase D3 and the solid phase D4 to the upper part of the mixer to the upper part of the mixer, and the pumping rate D5 of the mixture to the lance do not vary with time. In this stationary regime, the mixing chamber is mixed until a first level 27 separating the mixing chamber to the upper part 3 of the mixer. As soon as the water is brought into the upper part 3 at a level lower than that from which the solid phase is fed, there is formation in the kneader of a plurality of layers. This plurality of layers is successively composed, from the low level of the mixer 28 passing through the mixing outlet 10, to the high level of the mixer 29: a first mixing layer located between the levels 27 and 28, a second layer the liquid phase between levels 27 and 30, and a third layer of the solid phase between levels 29 and 30.

In stationary mode, it is the speed of rotation of the rotary arm of the Moineau pump which simultaneously governs the flow rate D5 of the mixture and the feed rate of the solid phase D2 to the mixing chamber.

In operation, it may happen that the delivery rate in liquid phase D3 (or solid phase D4) in the mixer, and therefore that the amount in the liquid phase (or the amount in solid phase) contained in the mixing chamber, vary over time.

For example, during the operation of the pump, the rotating rotor in the stator can induce a temperature increase localized in the compression stage which causes an expansion of the rubber sheath and results in a deformation of the cells which induces a reduction in their volume which has the effect that the solid phase flow to the mixing chamber is decreased. The mixture produced and pumped sees its solid phase load decreased and its reduced viscosity: it is more liquid and it does not stick to the wall.

In addition, as discussed above, in particular, the variation of the amount of water in the kneader can also alter the consistency of the mixture to be sprayed.

To overcome these disadvantages, it is provided according to the invention a method of mixing the liquid phase with the solid phase to form a mixture in which the sensor 24 measures, preferably continuously, the rheological variable at the level of the projection lance 14 giving a first value of rheological variable. This rheological variable value corresponds to the measurement of a parameter of the consistency of the mixture and may be, for example, the pressure of the mixture measured when the latter passes through the lance 14.

The sensor furthermore generates the first signal S1 transmitted to the control means 25 via the transmission line 11 which receives this first signal and generates the second signal S2 sent to the speed regulator 26 by the second transmission line 12. speed then processes the second signal and controls said motor rotating said kneading arm to regulate said speed of rotation of said kneading arm and thus regulate the second feed rate of said solid phase D2 and the pumping rate of the mixture D5 .

At the level of the control means, the first signal S1 is compared with a first reference signal corresponding to a second reference rheological variable value with the aid of a first comparison calculator of the control means. The second rheological variable value corresponds to a desired pressure value of the mixture associated with a consistency of the mixture that it is desired to reach at the outlet of the projection lance.

The first computer processes the first signal and the first reference signal as input to output the second signal S2 and send it to the speed controller.

This second signal S2 corresponds to a difference Δ calculated between, on the one hand, the first rheological variable value and, on the other hand, the second reference rheological variable value. In particular, the difference Δ corresponds to an absolute difference value between the first value (value measured by the sensor) and the second value (reference value).

The second signal, corresponding to an absolute deviation value Δ, is then processed at the input of the speed controller which decodes the second signal, compares with a second calculator the value of absolute deviation Δ at a second value. absolute difference threshold. If the first absolute difference value differs from the threshold value which may be a zero or non-zero value, the controller translates the second signal it has received into a variation of the rotation speed of the rotary arm via the actuator A for inducing a variation at a first amplitude simultaneously of the second feed rate of said solid phase D2 and the pumping rate of the mixture D5.

If the threshold value is defined as zero, it means that it is desired that the rheological variable value measured at the level of the lance 14 is strictly equal to the second reference rheological variable value. On the other hand, if the threshold value is set as a non-zero value, the measured rheological variable value is allowed to deviate from that of a second amplitude corresponding to said threshold value.

The variation of the second feed rate of said solid phase D2 and of the pumping rate of the mixture D5 is carried out until the first rheological variable value reaches the reference value or a value situated in a range of values determined by a non-zero threshold value.

In a particular embodiment of the device according to the invention, the sensor 24 is a strain gauge provided with a contact piece passing through the lance to be in contact with the mixture and which is arranged to undergo a deformation induced by the pressure. of the mixture. In operation, the strain gauge reflects this deformation undergone by the contact piece in variation of electrical resistance. This variation of electrical resistance is associated with a variation in intensity of an electric current corresponding to the signal S1 generated by the sensor and sent to the control means.

In a second particular embodiment of the invention, the control means is a proportional-integral-derivative type corrector. In this type of corrector, the first amplitude of the variation of the feed rates of the solid phase D2 and of the pumping of the mixture D5 is determined proportionally to the value of absolute difference Δ and to the integration of the deviation value. absolute in time, that is to say in practice to the sum of absolute deviation values Δ, measured over a given period of time.

It is understood that the present invention is in no way limited to the embodiments described above and that many modifications can be made without departing from the scope of the appended claims.

It is understood that the present invention is in no way limited to the embodiments described above and that many modifications can be made without departing from the scope of the appended claims.

Claims (15)

1. Device for projecting a mixture (1) comprising a kneader (2) provided with at least one liquid phase feed (8) and at least one solid phase feed (6), said kneader having a chamber mixer (4), said mixing chamber comprising an outlet (10) connected to an inlet of a compression stage (11) of a pump, said compression stage comprising an outlet of said mixture (12) connected to a first inlet port (13) of a spray lance (14) arranged to project said mixture through a second spray orifice (15) in an external environment (17), said mixer comprising at least one mixing arm (18) rotary apparatus passing through said mixing chamber, arranged to be moved at a rotation speed by a motor and to knead said solid phase with said liquid phase to form a kneading mixture, characterized in that said kneading arm is extended by a excen screw trolley (21) extending through said outlet (10) and terminating in said compression stage (11) of said pump, said pump being arranged to simultaneously pump said mixture to said mixing outlet (12) of said mixer and for pumping said solid phase to said mixing chamber (4), and in that it comprises control means (25) connected to a rheological variable sensor of said mixture (24) and to a speed controller of said engine (26). ), said sensor being associated with said projection lance (14) of said mixture and said speed regulator being arranged to act on said speed of rotation of the mixing arm, said control means being arranged to receive an emitted signal (S1) by the variable sensor and send a signal to said controller (S2) based on a value measured by the sensor. 2. Device according to claim 2, characterized in that said control means (25) is a proportional-integral-derivative type corrector. 3. Device according to any one of the preceding claims, characterized in that said regulator (26) is a frequency converter and the motor is an AC motor. 4. Device according to any one of the preceding claims, characterized in that said sensor (24) is a pressure sensor. 5. Device according to claim 5, characterized in that the pressure sensor (24) is a strain gauge. 6. Device according to any one of the preceding claims, characterized in that said liquid phase supply (8) is located at a level lower than that of said solid phase supply (6). 7. Device according to any one of the preceding claims, characterized in that said liquid phase comprises water. 8. Device according to any one of the preceding claims, characterized in that said solid phase is a pulverulent mineral material, in particular hydraulic, preferably comprising at least one element selected from the group of gypsum, sand, dry cement. 9. Device according to any one of the preceding claims, wherein said mixture has a liquid phase: solid phase ratio between 0.3 and 1, preferably between 0.4 and 0.8, preferably between 0.5 and 0. 7. A process for preparing a mixture of a solid phase with a liquid phase, comprising: a) supplying a liquid phase at a first rate (D1) into a mixing chamber (4) of a rotary kneader (2), b) feeding a solid phase to a second flow rate (D2) in said mixing chamber (4) of said rotary kneader (2), c) rotating kneading in said mixing chamber (4) of said solid phase with said liquid phase for forming a mixing mixture by a mixing arm (18) passing through said mixing chamber (4) and arranged to be set in motion at a rotational speed by a motor (23), d) a pumping said mixture to a third pumping rate (D5) to a mixing outlet (12) of said mixer (2) connected to a first inlet port (13) of a projection lance (14), e) a projection said mixture by a second projection orifice (15) of said projection lance traversed by said pro mixture from said mixing output, f) a measure of at least one rheological variable of said mixture giving a first rheological variable value which is encoded into a first signal (S1), g) a reception of said first signal by a control means (25) generating a second output signal (S2) to a speed controller (26) of said rotary motor (23), characterized in that said mixing arm (18) passing through said mixing chamber (4) is extended into a compression stage of a pump (11) where said step of pumping said mixture takes place, said mixing arm controlling said second flow (D2) for feeding said solid phase to said mixing chamber (4) and said third pumping rate (D5) of said mixture, and in that the step of measuring said rheological variable is performed at said projection lance (14), said speed regulator (26) processing said second output signal (S2 ) for ensu ite controlling said motor rotating said kneading arm and regulating said rotational speed of said kneading arm and inducing a variation simultaneously of said second feed rate of said solid phase and said third flow (D5) of pumping said mixture. The method according to claim 10, characterized in that it further comprises a first comparison step wherein said first signal (S1) is compared with a first reference signal corresponding to a second reference rheological variable value. using a first comparison calculator of said control means (25) inputting said first signal (S1) and said first reference signal to output said second signal (S2) and send it to said speed controller (26). The method according to claim 11, wherein said second signal corresponds to a difference calculated between, on the one hand, said first rheological variable value and, on the other hand, said second reference rheological variable value, said second signal (S2) being processed at the input of said speed regulator (26) which decodes said second signal and translates it into an output simultaneously a variation of said second feed rate of said solid phase (D2) and said third pump flow (D5) said mixture. The method of claim 12, wherein the step of processing said second signal by said speed controller (26) is a proportional-integral-derivative type control step. The method according to any one of claims 10 to 13, wherein said variation of said second feed rate of said solid phase (D2) and said third pump flow (D5) of said mixture is carried out until said at least one rheological variable reaches a predetermined value. The method of any one of claims 1 to 14, wherein said at least one rheological variable of said mixture is the pressure.