ITMI20111087A1 - COLLOIDAL MIXER TO PRODUCE FLUID CEMENT MIXTURES, AND MOBILE SYSTEM PROVIDED WITH THIS MIXER - Google Patents

Description

COLLOIDAL MIXER TO PRODUCE FLUID CEMENTITIOUS MIXTURES, AND MOBILE SYSTEM EQUIPPED WITH THIS MIXER

Field of the invention

[1] The present invention relates to a colloidal mixer particularly suitable for being part of mobile plants on trucks, vehicles or trailers, for the production of mortars and other fluid cement mixtures, including cellular concrete or cement slurries in general.

State of the art

[2] Fixed plants for producing cellular concrete equipped with a colloidal mixer are currently known; the latter makes possible a better and more intimate mixing of the cement granules in the water. Cement has a faster setting and greater mechanical resistance; settling less or not settling at all can be pumped more easily. The colloidal mixer is also of considerable help in the pumping of mortars or cement slurries, for example for filling large underground cavities, mines, in the pumping of sheaths in prestressed cables, or of mortars at great distances.

[3] Plants for the production of cellular concrete or even generic mortars or concretes, mounted on trucks, are also known. These mobile plants are equipped with cement silos, sand tanks, tanks for mixing water, tanks for additives, foaming agents, and are particularly advantageous for making substrates for civil and industrial buildings.

[4] Current colloidal mixers have a relatively complex construction, with impellers driven, by means of shafts, by motors located outside the chambers in which the impellers themselves are housed, thus requiring appropriate sealing gaskets and generally complicating the mechanical construction of the mixer.

The mechanical construction of known mixers is also complicated because the impellers are fixed to an upper end of their transmission shaft, or are housed in a chamber outside the mixing tank; in particular, for this reason too, seals are required.

[5] For the above reasons, known colloidal mixers are not suitable for being part of truck-mounted cellular concrete production plants. In addition, due to the high rotational speeds of the driveshaft or other components, the seals are subject to considerable wear and must be replaced frequently.

Cellular concrete production plants mounted on trucks or other vehicles, and equipped with a colloidal mixer would be highly desirable because they would combine the aforementioned advantages of the colloidal mixer with those of mobility on a vehicle or more generally on a vehicle.

[6] Therefore an object of the present invention is to provide a colloidal mixer for producing fluid mixtures of water and cement which is more suitable, than known colloidal mixers, to be mounted on a truck or other motor vehicle.

Summary of the invention

[7] This object is achieved, in a first aspect of the invention with a colloidal mixer having the characteristics according to claim 1.

In a second aspect of the invention, this object is achieved with a mobile plant for producing fluid cement mixtures having the characteristics according to claim 13.

[8] Further characteristics of the device are the subject of the dependent claims.

The advantages achievable with the present invention will become more evident to those skilled in the art from the following detailed description of a particular non-limiting example of embodiment, illustrated with reference to the following schematic figures.

List of Figures

Figure 1 shows a perspective view of a colloidal mixer according to a particular embodiment of the invention;

Figure 2 shows a sectional view, according to a vertical section plane II-II, of the colloidal mixer of Figure 1;

Figure 3 shows a sectional view, according to a vertical section plane III-III, of the colloidal mixer of Figure 1;

Figure 4 shows a sectional view, according to the section plane IV-IV, of the turbulence chamber and the rotor of the colloidal mixer of Figure 1;

Figure 5 shows the side view of a mobile plant for fluid cement mixtures mounted on a truck and comprising the colloidal mixer of Figures 1-4;

Figure 6 shows the rear view of the mobile implant of Figure 5.

Detailed description

[9] Figures 1-6 relate to a colloidal mixer for producing fluid cement mixtures, such as for example water and cement based mixtures to obtain cellular concrete, according to a particular embodiment of the invention.

This mixer, indicated with the overall reference 1, comprises a main body 3 made for example of welded metal sheet, a inside which a premixer 5 and a fine mixer 7 are housed (Figure 1).

[10] The premixer 5 in turn comprises a mixing chamber 9 designed to receive, even separated from each other, the water and cement to be mixed together and to favor at least a first, coarser one, mixing forming a mixture coarse fluid of water and cement. The fine mixer 7 comprises a mixing rotor 11, a shaft or other transmission system 13 and a swirl chamber 15 containing the mixing rotor 11 and the transmission shaft 13 (Figure 2).

As shown in Figures 2, 3, the turbulence chamber 15 can have a substantially cylindrical shape, for example.

[11] Figure 4 shows in top view a possible shape of a rotor 11 usable in the mixer 1. The transmission shaft 13 comprises an actuation portion 130 arranged to receive motion from a suitable motor, for example an electric motor , hydraulic or compressed air. As shown in Figure 3, the transmission system 13 can comprise a transmission belt 133 which engages with the drive portion 130 by means of suitable pulleys.

[12] Preferably the motor or more generally the mixer 1 is arranged to rotate the mixing rotor 11, during its normal operation, at a rotation speed between 100 and 2000 rpm, more preferably between 1600- 2000 rpm and, even more preferably around 1800 rpm. Advantageously, the motor or, more generally, the mixer 1 is arranged to accelerate the rotor up to these speeds, and to decelerate it until it stops, in a sufficiently long time and with sufficiently gradual and contained accelerations and decelerations, for example with ramps of substantially linear acceleration or deceleration lasting not less than 3 seconds, more preferably not less than 5 seconds, and even more preferably not less than 10 seconds. The gradual accelerations and decelerations improve the mixing of the various components, especially when entering the mixing chamber 9; they stress the treated mixture less; moreover, they lengthen the operating life of the mixer 1 making the high number of starts and stops which often characterizes the use of this type of machines less harmful. In fact, these machines are often turned on for no longer than 3-4 minutes at a time, even tens or hundreds of times a day.

For these purposes the mixer 1 is provided with a motor speed regulation system, for example a system with inverters.

[13] According to an aspect of the invention, during the normal operation of the colloidal mixer 1 the mixing rotor 11 is arranged to favor, by rotating on itself, a second, more intimate and fine mixing of water and cement, activated by the mixing system transmission, and the mixing rotor 11, as shown in Figures 1-3, is arranged substantially lower than the drive portion 130. For this purpose, preferably the drive shaft 13 is arranged to be arranged and rotated, during the normal operation, around a vertical axis AR, where by "vertical", in the present description, is meant inclined with an angle not exceeding 40 degrees with respect to the direction of a plumb line.

As shown in Figures 2, 3, preferably the drive shaft 13 extends through the mixing chamber 9. Preferably the portion of the drive shaft 13 which extends through the mixing chamber 9 and in the possible intermediate chamber 17 is substantially free of radial blades or pins designed to mix the contents of the chamber itself; this allows a better and more efficient mixing of the cement powder and the water entering the chamber 9, even in the face of very high speeds of rotation of the shaft 13 as exemplified above.

[14] Advantageously, the drive shaft 13 is substantially straight. Advantageously, the drive shaft 13 reaches the swirl chamber being mounted as a cantilever beam forming a free end, and the mixing rotor 11 is closer to this free end than to the drive portion 130 (Figures 2, 3) . For this purpose, advantageously, during normal operation, the turbulence chamber 15 is arranged substantially under the mixing chamber 9.

As shown in Figures 2, 3, the mixing chamber 9 can have a substantially cylindrical upper part. Advantageously, the mixing chamber 9 has a lower end 90 which tapers progressively downwards, so as to collect and direct the coarse mixture of water and cement formed in the mixing chamber towards the turbulence chamber 15. This lower end 90 can for example, have a substantially truncated cone shape (Figures 2, 3), truncated pyramid or stepped.

[15] Advantageously, an intermediate chamber 17 is interposed between the mixing chamber 9 and the swirl chamber 15, communicating with the mixing chamber 9 through a first supply opening 149, and communicating with the swirl chamber through a second opening power supply 150.

The first 149 and the second supply opening 150 have passage sections substantially smaller than the maximum cross sections of the mixing chamber 9, the intermediate chamber 17 and the swirl chamber 15. In the present description, the maximum and non-maximum cross sections of the chamber of the mixing chamber 9 and of the turbulence chamber 15, are to be understood as referring to ideal section planes perpendicular to the axis of the drive shaft 13. As shown in Figure 2, advantageously the drive shaft 13 enters the turbulence chamber 15 by passing through the second feed opening 150.

[16] Advantageously, the area of the passage section of the first 149 and / or second supply opening 150, net of the dimensions of the shaft 13, is substantially equal to or less than one third of the maximum cross section of the swirl chamber 9 or of the mixing chamber 15.

[17] Advantageously, the area of the passage section of the first 149 and / or of the second supply opening 150 is substantially equal to or less than 0.15 times the maximum cross section of the mixing chamber 15.

Alternatively, advantageously, the diameter or in any case the width of the first 149 and / or second feeding opening 150 are comprised between three quarters and three eighths of the maximum diameter or width of the rotor 11.

As shown in Figure 1, the intermediate chamber 17 and the turbulence chamber 15 can be closed at the top each by a respective circular plate 154, 155 in which the first 149 and the second supply opening 150 are respectively obtained. Preferably the plates 154, 155 are basically flat. Advantageously, between the edges of the plates 149, 150 and the sides of the drive shaft 13 there is a relatively abundant passage opening. For this purpose, preferably the surface of this passage opening is equal to or greater than about four times the cross section of the shaft 13 at the height of the openings 149, 150 respectively. More preferably the area of the passage openings of the openings 149 and / o 150 is equal to or greater than about eight times the aforementioned cross section of shaft 13.

[18] Thanks to the above dimensions of the first 149 and second feed opening 150 and of the shaft 13, a better, more intimate and finer mixing of the cement in water in the turbulence chamber is obtained; the drive shaft 13 is able to enter the turbulence chamber 15 without any need for sealing gaskets, and with a very simple mechanical construction allowing to create light colloidal mixers, not bulky and suitable to be mounted on trucks, other vehicles or in any case as part of plants for the production of fluid mixtures of water and cement or other fluid cementitious mixtures.

[19] Preferably the mixing chamber 9 communicates with the outside through an upper access opening 92 which allows water and cement powder and any other components of the mixture to be introduced by pouring them (Figure 1). Advantageously, the upper access opening opens in the upper part of the main body 3.

Advantageously, the aforementioned actuation portion 130 is located outside the mixing chamber and much higher than the normal level of the cement mixture present in the mixing chamber 9 during normal operation. In this way the drive shaft 13 can enter the mixing chamber through a simple hole 94 without gaskets (Figures 1-3).

[20] Advantageously where the drive shaft 13 is arranged in a substantially eccentric position with respect to the mixing chamber 9 (Figure 3): this facilitates and makes the introduction of water, cement powder and any other components easier and more convenient of the mixture to be produced.

Advantageously, the colloidal mixer 1 comprises a recirculation duct 19 designed to withdraw the fine fluid mixture from the turbulence chamber 15, and introduce at least part of it into the mixing chamber 9 (Figure 2). The fine mixture produced in the turbulence chamber 15 can be extracted from the mixer 1 through a discharge mouth 21 which branches off from the recirculation duct 19. For this purpose, preferably the discharge mouth 21 can be reversibly closed and opened by means of a plug or a suitable tapping valve 23.

[21] Advantageously, in general, the discharge mouth 21 is arranged to discharge the fluid cement mixture from the mixer 1 by simple fall, or in any case by simple gravity and without resorting to pumps, compressors or other motors. In this way the content, pre-dosed, is easily and completely discharged.

The recirculation duct preferably opens in the upper part of the mixing chamber 9 through the mouth 190, and the fine fluid cement mixture formed in the turbulence chamber can rise along the recirculation duct 19 thanks to the head created by the rotor 11. Preferably the flow duct recirculation 190 enters the mixing chamber 9 with a tangential direction, or mainly tangential, with respect to the walls or the central axis of the chamber 9 itself so that the jet of mixture coming out of the mouth 190 gives a swirling motion to the material already present in the mixing chamber 9.

[22] An example of operation of colloidal mixer 1 is now described.

The water and the cement powder are introduced into the mixing chamber 9, for example by pouring them into the upper access opening 92, and are remixed by the jet of fluid fine cement mixture already formed coming out of the mouth 190. The coarse fluid mixture of water and cement thus formed in the mixing chamber 9 descends by gravity into the intermediate chamber 17 and from there into the turbulence chamber 15 passing through the first 149 and the second supply opening 150, in particular passing through the abundant passage gaps between the shaft 13 and the edges of openings 149 and 150.

[23] In the intermediate chamber 17, thanks to its suitable construction previously described, the fluid cement mixture formed in the mixing chamber 9 loses speed and increases its pressure, preventing - or in any case reducing - backflow of the mixture from the turbulence chamber upstream, or upwards and towards the intermediate chamber 17 and mixing chamber 9. By rotating at high speed in the turbulence chamber 15, the rotor 11 accelerates again and mixes more intimately and finely the fluid cement mixture coming from the intermediate chamber 17 or in any case from the mixing chamber mixing 9, and pushes it into the recirculation duct 19.

The ready fluid cement mixture can be extracted from the mixer 1 by opening the cap or the tapping valve 23. Otherwise, keeping the cap or the tapping valve 23 closed, but the fluid cement mixture rises along the duct 19 to the opening 190, and through the latter returns to the mixing chamber 9.

[24] Thanks to the previous teachings it is possible to realize a colloidal mixer which is constructively very simple, light, compact and not bulky, and therefore very suitable to be mounted on board trucks, other vehicles or on their trailers, or other vehicles such as railway wagons or boats, or in any case as part of plants for the production of fluid mixtures of water and cement or other fluid cementitious mixtures, with all the consequent advantages set out in the initial part of this application.

[25] A mobile plant 50 for the production of fluid cement mixtures equipped with the colloidal mixer 1 can comprise for example (Figures 4, 5):

- a sand silo 51 with a sand extraction belt 53;

-a powder cement silos 55 provided with one or more extraction augers 57, to send the powder cement to the colloidal mixer 1;

-a tank for mixing water 59 and relative metering pump 61; reference 63 indicates the pipe which carries the water coming out from the delivery of pump 61 to the mixer 1;

- any distributors of powder additives (not shown);

-an ordinary mixer 65 of the non-colloidal type, also referred to in the present description as "low speed mixer 65";

-a generator of

of a per se known type and comprising a pressure pump and air compressor;

-a pump for delivering the mixture of fluid cellular concrete 67, for example with a variable flow rate of 5-25 cubic meters / hour.

[26] The ordinary mixer 65 comprises an upper open tank in which rotates an impeller equipped with suitable blades or radial pins (not shown). The impeller of the mixer 65 rotates at substantially lower angular speeds than the rotor 11 of the colloidal mixer 1, for example not exceeding 40-120 rpm.

The fluid cement mixture produced by the colloidal mixer 1, the sand from the silos 51 and any other powder or granular additives such as expanded polystyrene, perlite or vermiculite can be poured into the tank of the ordinary mixer 65. Alternatively, the upper open tank of the ordinary mixer 65 can be replaced by a substantially closed tank in its upper part.

[27] Advantageously, the ordinary mixer 65 is arranged below or in any case lower than the turbulence chamber 15, so as to be able to discharge the fluid cement mixture produced by the mixer 1 simply by gravity. For this purpose, preferably the aforementioned tank or tank of the mixer 65 is arranged below or in any case lower than the discharge mouth 21, so as to be able to pour the cement mixture coming out of the mouth 21 directly into the ordinary mixer 65.

The mobile plant 50 can be set up to produce:

- is cellular concrete, with foam and with or without sand, of variable density from 200 to 1700 kg / cubic meter;

-both mortars to be used as substrates for building, or high-strength fluid mortars.

[28] To produce cellular concrete, the mixture formed and amalgamated in the mixer 65 is joined to the foam produced by the aforementioned foam generator and then to the delivery pump 67. For the production of non-cellular cements, the mixture coming out of the mixer 65 is instead sent to the pump 67 or other suitable extraction devices.

As shown in Figures 4, 5, the plant 50 can be advantageously mounted for example on a truck 69, preferably on the rear part of the latter.

[29] The embodiments described above are susceptible to various modifications and variations without departing from the scope of protection of the present invention. Furthermore, all the details can be replaced by technically equivalent elements. For example, the materials used, as well as the dimensions, may be any according to the technical requirements. The intermediate chamber 17, substantially cylindrical in shape, can be replaced for example by chambers of different shape or by one or more diffusers having a substantially conical shape.

The examples and lists of possible variants of this application are intended as non-exhaustive lists.

Claims (15)

CLAIMS 1) Colloidal mixer (1) to produce fluid cement mixtures, for example based on water and cement, comprising a pre-mixer (5) and a fine mixer (7), where: -the premixer (5) in turn comprises a mixing chamber (9) designed to receive, even if separated from each other, the water and cement to be mixed together and favor at least a first, coarser one, mixing forming a coarse fluid mixture of water and cement; -the fine mixer (7) comprises a first mixing rotor (11), a transmission system (13) and a swirl chamber (15) containing the first mixing rotor (11) and at least part of the transmission system (13 ); - the transmission system (13) comprises an actuation portion (130) arranged to receive motion from a motor; - during normal operation of the colloidal mixer (1) the first mixing rotor (11) is designed to favor, by rotating, a second, more intimate and fine mixing of water and cement, activated by the transmission system (13), and the first mixing rotor (11) is arranged substantially lower than the driving portion (130). 2) Colloidal mixer according to claim 1, wherein the transmission system comprises a substantially vertical drive shaft (13). 3) Colloidal mixer according to claim 2, where the drive shaft (13) extends through the mixing chamber (9) and reaches the swirl chamber (15) being mounted as a cantilever and forming a free end , and the first mixing rotor (11) is closer to the free end than to the driving portion (130). 4) Colloidal mixer according to claim 2, wherein the drive shaft (13) is arranged in a substantially eccentric position with respect to the mixing chamber (9). 5) Colloidal mixer according to claim 1, arranged so that, during its normal operation, the turbulence chamber (15) is arranged substantially below or below the mixing chamber (9). 6) Colloidal mixer according to claim 1, comprising an intermediate chamber (17) in fluid communication upstream with the mixing chamber (9) and downstream with the turbulence chamber (15), and arranged in such a way as to slow down the fluid cement mixture coming from the mixing chamber (9) and increase its pressure before it enters the turbulence chamber (15). 7) Colloidal mixer according to claim 1, wherein the mixing chamber (9) has a lower end (90) which gradually narrows downwards. 8) Colloidal mixer according to claim 1, where the turbulence chamber (15) has a second feed opening (150) through which it can receive the coarse fluid mixture of water and cement coming from the mixing chamber, and the second opening of feed (150) has a passage section substantially smaller than the maximum cross sections of the mixing chamber (9) and / or of the swirl chamber (15). 9) Colloidal mixer according to claim 8, where the passage section of the second supply opening (150) is substantially equal to or less than one third of the maximum cross section of the swirl chamber (15) or of the mixing chamber (9). 10) Colloidal mixer according to claim 8, where the passage section of the second supply opening (150) is substantially equal to or less than 0.15 times the maximum cross section of the mixing chamber (9). 11) Colloidal mixer according to claim 1, arranged to rotate the first mixing rotor (11), during its normal operation, at a rotation speed of between 100 and 2000 rpm. 12) Colloidal mixer according to claim 1, comprising a recirculation duct (19) designed to withdraw the fine fluid mixture of water and cement obtained in the turbulence chamber (15) from the second and more intimate and fine mixing of water and cement, and introduce at least part of this fine fluid mixture into the mixing chamber (9). 13) Mobile plant for producing fluid cement mixtures (50), comprising a vehicle (69) on which are mounted a plant for the production of cellular concrete or other fluid mortars, and a colloidal mixer (1) having the characteristics according to one of the claims 1 to 12. 14) Mobile plant (50) according to claim 13, comprising a low speed mixer (65) comprising a tank or tank and a second mixing rotor designed to mix fluid cement mixture by rotating in the tank or tank at angular speeds substantially lower than the speeds of rotation of the first mixing rotor (11), and where: - the low speed mixer (65) designed to be fed with and remixed the fluid cement mixture produced by the colloidal mixer (i); -the tank or tank of the low speed mixer (65) is arranged below or in any case lower than the turbulence chamber (15), so as to be able to discharge the fluid cement mixture produced by the mixer (1) simply by gravity. 15) Mobile plant (50) according to claim 13, where the vehicle (69) is selected from the following group: a truck, a motor vehicle, a motor vehicle trailer, a railway wagon, a boat.