EP2822744B1

EP2822744B1 - Mobile mixer installation for controlled continuous mixing of granular material with at least one admixture

Info

Publication number: EP2822744B1
Application number: EP13715118.9A
Authority: EP
Inventors: Guy KEMPENEERS
Original assignee: ETS Gygro NV
Current assignee: ETS Gygro NV
Priority date: 2012-03-05
Filing date: 2013-03-05
Publication date: 2016-05-18
Anticipated expiration: 2033-03-05
Also published as: WO2013131152A2; EP2822744A2; BE1020517A3; WO2013131152A3

Description

The invention concerns a mobile mixer installation for the controlled continuous mixing of granular materials with an admixture. The mobile mixer installation may assume a transport condition and a working condition and has a basic frame with a supply side and a delivery side. On this basic frame are provided a dosing device, at least one silo, preferably a feed belt and a mixer.
In said working condition, an outlet of the dosing device opens above the feed belt on the supply side of the mixer installation. The feed belt opens into an inlet of the mixer in order to put supplied granular materials in the mixer. The mixer has an output on the delivery side. Further, an outlet of said silo also opens in the inlet of the mixer.
Such a mixer installation is used for example to immobilize unwanted contaminants in a soil. To this end, the soil is excavated over a certain thickness and the excavated soil containing the contaminants is mixed with an admixture, optionally while adding water, in order to immobilize the contaminants. After the mixing is completed, the mixture of ground and admixture is spread out over the soil again.
Another application for the use of such a mixer installation is stabilizing a substrate in order to improve the bearing capacity of this substrate, for example, so as to make it suitable for raising building structures. In that case, the available soil is mixed with an admixture such as lime, cement and/or fly ash, optionally while adding water, and spread out again in a compact layer over the soil.
Mobile mixer installations are also frequently used in road constructions. A granular material such as for example gravel is hereby mixed with an admixture, such as cement and/or lime, and water in order to produce a finished product, for example concrete, which can be used as a foundation for roads.
When performing works with a mobile mixer installation, it is extremely important that the used mixing ratio of the granular materials and admixtures can be checked and adjusted if necessary. In addition, it is necessary that a large flow rate of granular material can be processed in a short time since the bottom surfaces for which such mixer installations are used are normally very substantial.
Documents WO 2007/105017 A1 and EP 2266770 A2 disclose mixer installations for the production of various concrete compositions.
Further, document GR 1006037 B2 discloses a mobile mixer installation according to the preamble of claim 1.
It turns out, however, that it is not possible with the existing mobile mixer installations and methods to allow for a continuous operation at a large flow rate in this context while at the same time continuously checking the mixing ratio of granular material and admixture. Since mobile mixer installations must normally be transported over public roads, there are significant limitations on the size of these installations, in particular as far as their height, length and width is concerned. This has consequences for the size of the feed-through openings for granular material, admixture and finished product and of the silo in the existing mixer installations. In particular, these feed-through openings are relatively small in relation to the flow rate of finished product one wishes to obtain, which often results in obstructions. Moreover, each time the silo with admixture is empty, the operation of the mixer installation must be interrupted in order to fill the silo with admixture again. Indeed, when the silo is filled during the operation of the mixer installation, it is no longer possible to determine the actual mixing ratio of granular material and admixture in a correct manner by weighing.
The invention aims to remedy these disadvantages by providing a mobile mixer installation in accordance with claim 1 which make it possible to move the mixer installation in a transport condition and to mix a large flow rate of granular material and admixture in a working condition in a continuous manner without any interruptions while the mixing ratio is continuously checked even though admixture is being added to the mixer installation.
To this aim, said mixer is hinge-mounted to the basic frame on said delivery side via a mixer pivot shaft, whereas the inlet of the mixer is hinge-mounted to the delivery end of said feed belt, whereby the silo is hinge-mounted via a silo pivot shaft to a first end of a supporting arm whose opposite second end is hinge-mounted to the basic frame. Thus, said silo is put from the working condition into the transport condition by rotating said supporting arm around the hinged connection on said second end, such that said first end of the supporting arm is moved to said supply side. The silo is hereby moved to the supply side into a lower position. The mixer is moved from the working condition into the transport condition by subjecting it to a rotation around the mixer pivot shaft into a lower position.
Preferably, said silo works in conjunction with a silo weighing device.
According to a preferred embodiment of the mixer installation according to the invention, it contains at least two separate silos which are each provided with a silo weighing device. Preferably, these silos extend parallel to one another and they are moved together between the transport condition and the working condition of the mixer installation.
According to a special embodiment of the mixer installation according to the invention, said feed belt comprises a belt weighing device.
Advantageously, said silo has at least one supporting member on its supply side, one far end of which is fixed to said silo, whereas the opposite far end of this supporting member is led by a guide when the silo is being moved between the working position and the transport position. This guide is provided on said basic frame, such that its height increases from the supply side to the delivery side.
According to a particularly interesting embodiment of the mixer installation according to the invention, it contains a delivery conveyor belt which extends as of the delivery side of the basic frame. The outlet of said mixer hereby opens in this delivery conveyor belt in the working condition.
Further, the mixer installation according to the invention optionally contains at least one water tank which is connected to the inlet of said mixer.
Other particularities and advantages of the invention will become clear from the following description of some specific embodiments of the mobile mixer installation according to the invention. This description is merely given as an example and does not restrict the scope of the claimed protection in any way; the reference numbers used hereafter relate to the accompanying figures.

Figure 1 is a schematic side view of a mobile mixer according to the invention in the working condition.
Figure 2 is a schematic side view of the mobile mixer from figure 1 in the transport condition.
Figure 3 is a schematic top view of the mobile mixer from figures 1 and 2 when it is in the working condition.
Figure 4 is a schematic top view to a larger scale of the silos of the mixer installation from the preceding figures.

In the different figures, the same reference numbers refer to identical or analogous elements.
The mixer installation according to the invention, as represented in the figures, has a basic frame 1 with a supply side 2 and a delivery side 3. This basic frame 1 is provided with a dosing device 4, two silos 5 and 6, a feed belt 7 and a mixer 8.
According to the invention, this mixer installation may assume two conditions. In a working condition, as represented in figures 1 and 3, the mixer installation can be used for mixing a granular material with an admixture, possibly while adding water in a continuous mixing process. Figure 2 represents the mixer installation in its transport condition. In this transport condition, the installation can be moved independently or it can be loaded on a semi-trailer, and by means of this semi-trailer it can be moved on public roads.
As shown in figure 1, the dosing device 4 consists of a container with an open top side 9 via which it can be loaded with granular materials to be mixed. The bottom side of the dosing device 4 has an outlet 10 which opens above the supply side 11 of said feed belt 7.
This feed belt 7 is inclined, such that its height increases from the supply side 2 to the delivery side 3 of the basic frame 2. The feed belt 7 opens at the inlet 12 of the mixer 8, such that granular material of the dosing device 4 can be fed into the mixer 12.
Further, the feed belt 7 preferably comprises a belt weighing device making it possible to practically continuously measure the weight of the granular material which is being moved over the conveyor belt. In particular, it is possible to determine the weight of the granular material which is moved from the dosing device 4 to the mixer 8 per unit of time. Thus, it is possible to check the amount of granular material which is put in the mixer 8.
Naturally, the amount of granular material which is moved to the mixer 8 can be determined in alternative ways. Thus, it is possible for example to determine this amount by measuring the volume of the granular material being added to the mixer per unit of time. The latter can be done by measuring the volume of granular material being moved over the conveyor belt electro-optically, for example by means of a moving laser beam. More specifically, various mass transport measuring systems can be applied for measuring the amount of granular material which is put in the mixer 8.
At the bottom, the mixer 8 has an output 13 on the delivery side 3 of the basic frame 1. In particular, the mixer 8 consists of a double-axle mixer formed of a container in which two parallel mixing shafts 14 and 15 extend in the longitudinal direction of the mixer installation, as shown in figure 3. The longitudinal direction of the mixer installation corresponds to the direction of the product flow from the supply side 2 to the delivery side 3. These mixing shafts are provided with blades 16 and they rotate around their axes when granular materials are to be mixed with admixture. Each of the mixing shafts 14 and 15 is driven by an electric or hydraulic motor 17.
Further, said silos 5 and 6 each have a downward directed outlet 18 and 19 respectively. These outlets 18 and 19 also open into the inlet 12 of the mixer 8 in said working condition.
Each of the silos 5 and 6 cooperates with a corresponding silo weighing device. To this end, the silos 5 and 6 are mounted independently and separately from one another in a silo frame 22, and they each rest via at least one sensor, for example pressure sensors 23 and 24, on this silo frame 22. To this end, the silo frame 22 has a horizontally extending support beam 25 on which said pressure sensors 23 and 24 are mounted. This support beam 25 of the silo frame 22 is represented in figures 3 and 4.
In general, the silo weighing device may contain one, two, three or more sensors, for example pressure sensors, per silo which make it possible to measure the weight of each of the silos, preferably continuously, and possibly to record it as well.
The silo weighing device makes it possible to measure the weight of each silo 5 and 6 individually and to thus determine how much admixture leaves the silo 5 or 6 per unit of time. Since the silos 5 and 6 are mounted independently and separately from one another in the silo frame 22, it is possible to top up a silo 5 while admixture from the other silo 6 is being processed in the mixer installation, whereby it is thus continuously determined how much admixture is being put in the mixer 8.
Each of the silos 5 and 6 is formed of a closed container which is provided with a worm screw 26 and 27 in the bottom, driven by an electric engine 28. Thus, by driving the worm screw 26 or 27, admixture can be led to the respective outlets 18 or 19 of the silos 5 or 6.
On the delivery side 3 of the basic frame 1 is mounted a delivery conveyor belt 20 which is inclined, such that under its free end 21 for example a lorry with an open stowage space can be placed so as to load it with finished product which has left the mixer 8. To this end, the outlet 13 of the mixer 8 opens above the lower end of the delivery conveyor belt 20 in the working condition.
The delivery conveyor belt 20 further has a horizontal pivot shaft 29, such that a first part 30 on the side of the free end 21 of this delivery conveyor belt can be moved around this pivot shaft in relation to a second part 31 thereof. To this end, the first part 30 is driven for example in relation to the second part 31 by a hydraulic piston which is not represented in the figures.
According to an interesting embodiment of the mixer installation according to the invention, it contains at least one water tank which is connected to the inlet 12 of the mixer 8. In the mixer installation represented in the figures, two such water tanks 46 and 47 are provided on the basic frame 1. These water tanks 46 and 47 extend more specifically on either side of the feed belt 7 and under the silo frame 22, and they open in the inlet 12 of the mixer 8 via a water pipe and pump installation which are not represented in the figures.
The delivery conveyor belt 20 preferably cooperates with a belt weighing installation so as to continuously measure the weight of the finished product after it has left the mixer 8. On the basis of this weight measurement, the moisture content of the finished product is then determined, taking into account the amount of granular material and admixture which have been fed in the mixer 8. The determined moisture content is then compared with the desired moisture content of the finished product, such that the flow rate of the water supply to the mixer 8 may possibly be adjusted.
The moisture content of the finished product can be determined in an alternative manner by providing a moisture meter or a sensor in the product flow or on the output of the mixer 8. Such a sensor works for example by means of microwaves and allows to measure the moisture content of the finished product almost continuously. An appropriate sensor is for example the so-called "Hydro-Probe II" of Hydronix Ltd. from Guildford, Surrey, Great-Britain.
As a function of the measured moisture content of the finished product, water is added to the mixer so as to obtain a finished product with a desired moisture content.
In order to put the mixer installation from the above-described working condition into the transport condition, said mixer 8 is hinge-mounted to the basic frame 1 on the delivery side 3 thereof via a mixer pivot shaft 32. Further, the inlet 12 of the mixer 8 is hinge-mounted to the delivery end 33 of said feed belt 7.
Such an assembly allows to move the mixer 8 from the working condition into the transport condition by subjecting it to a rotation around the mixer pivot shaft 32 into a lower position until it rests with its supply side on a bearing surface of the basic frame 1, which surface is not represented in the figures.
Since the feed belt 7 is hinge-mounted to the inlet 12 of the mixer 8, its delivery end 33 is moved down as well. In order to allow this, the supply side 11 of said conveyor belt 7 is movably connected to the basic frame 1.
In the preferred embodiment of the invention as represented in the figures, the feed belt 7 on the supply side 2 of the basic frame 1 is suspended on each side by means of a cylindrical cam 34 which is fixed to the basic frame 1 and whose axis extends transversely to the longitudinal direction of the conveyor belt 7. This cam 34 is guided in an elongated slot 35 provided laterally to the feed belt 7. Such a movable connection allows the feed belt 7 to be subjected to a translation as well as to a rotation in relation to the basic frame 1.
Naturally, it is also possible to provide a cylindrical cam on either side of the feed belt 7, whereby this cam is then guided in a corresponding slot which is fixed to the basic frame 1.
Further, in the working condition, the mixer 8 is supported by an elongated upright support element 43 which is hinge-mounted with one far end to the mixer 8. The far end 44 of this supporting element 43 which is opposite to the mixer 8 rests on a bearing surface 45 of the basic frame 1 in this working condition.
In order to put the mixer 8 in said transport condition, the support element is rotated around its hinged end whereby the opposite end 44 thereof slides over the bearing surface 45 until it adopts an inclined or horizontal position when the mixer 8 is in said transport condition.
When the feed belt 7 and the mixer 8 have thus been put in the transport condition, as shown in figure 2, it is possible to lower the silo frame 22 with the silos 5 and 6 to the thus freed space.
To this end, the silos 5 and 6 are connected with hinges, via a silo pivot shaft 36, to a first end 37 of a supporting arm 38 whose opposite second end 39 is hinge-mounted to the basic frame 1. The silos are more specifically connected with hinges to said supporting arm 38 via said support frame 22. The supporting arm 38 is driven by a hydraulic piston 48, one end of which is laterally attached to the basic frame 1 on a support 49 provided to that end.
The silos 5 and 6 are thus put from the working condition into the transport condition by rotating said supporting arm 38 around the hinged connection on said second end 39, such that said first end 37 of the supporting arm 38 is moved towards said supply side. The silos 5 and 6 are thus moved into a lower position together with the support frame 22.
On the supply side 2 of the basic frame, the silos, more specifically the basic frame 22, have a supporting member 40, one end of which is fixed in relation to the silos, whereas the opposite far end of this supporting member 40 is led by a guide 41 when the silo is being moved between the working position and the transport position.
Said supporting member 40 is formed in particular of a substantially vertically extending beam which is rigidly connected to the silo frame 22. To this end, this silo frame has a beam 42 extending horizontally under the silos 5 and 6 onto which one far end of the supporting member 40, in other words the vertical beam, is rigidly connected.
Said guide 41 for the opposite end of the supporting member 40 is formed of a flat strip provided transversally to an upright wall of the basic frame on either side of the feed belt 7. The height of this guide 41 hereby increases from the supply side 2 towards the delivery side 3. For the sake of completeness, it should also be mentioned that two supporting members 40 are provided which each extend on one side of the feed belt 7.
The basic frame 1 is supported on either side by caterpillars 50, such that the mobile mixer installation can be moved into the transport condition.
In order to mix a granular material, such as for example sand or gravel, with an admixture, such as lime or cement, possibly while adding water, in order to obtain a finished product, the granular material is loaded in the dosing device 4 and led from this dosing device 4 to the mixer 8 by the feed belt 7. The amount of granular material which is led to the mixer 8 is hereby continuously measured by measuring the weight and the speed of movement of the granular material while it is being moved over the feed belt 7. Thus is determined the amount of granular material being fed to the mixer 8 per unit of time. As mentioned above, also a volumetric measurement of the amount of granular material being brought to the mixer is possible.
Further, an admixture from a first silo 5 is added to the granular material in the mixer 8 while the weight of this silo 5 is being measured almost continuously in order to determine the amount of admixture being fed to the mixer 8 per unit of time. The granular material and the admixture are continuously mixed in the mixer 8 and, after having been mixed, they leave the mixer 8 via the outlet 13 as a finished product. This finished product is thus cast onto the delivery conveyor belt 20 and loaded for example in a lorry via the latter.
When the first silo 5 is almost emptied, the addition of admixture from this first silo 5 is interrupted, and admixture from the second silo 6 is then added to the granular material in the mixer 8. The weight of this second silo 6 is hereby also measured almost continuously. Meanwhile, the first silo 5 is filled again with admixture.
Naturally, in order to determine the amount of admixture being brought into the mixer from each of the silos, a weight measurement of these silos is not strictly necessary. Thus, it is also possible to measure the volume of the admixture available in the silos or to measure the volume which leaves the silo concerned. In general, any system whatsoever can be applied which allows to determine the mass transport from each individual silo to the mixer.
By proceeding in this manner, it is possible to mix a very large flow rate of granular materials and admixtures without having to stop the operation of the mixer installation for example to top up admixtures in one of the silos.
If required, apart from said admixtures also other additives can be added to the mixture in the mixer, such as for example plasticizing additives.
For the sake of completeness should be mentioned that the inclination of the mixer in relation to a horizontal plane can be adjusted in order to regulate the length of stay of the mixture in the mixer. By for example relatively raising the position of the output of the mixer in relation to the inlet thereof, the length of stay of the mixture in the mixer increases, which consequently results in a more intense mix. To this end, the mixer is supported for example by a hydraulic piston which allows to move the mixer into a desired inclined position.
The amount of granular material and the amount of admixture and/or the ratio of these amounts being fed to the mixer 8 are continuously registered.
According to a further variant an extraction system which is not represented in the figures is mounted on said mixer 8. This extraction system is equipped with a dust filter and draws air from the enclosed volume of the mixer 8 in order to generate an air flow from the silo, which supplies admixture to the mixer, towards the mixer 8. Thus, the content of the silo concerned and the mixer are at a negative pressure with respect to the environment. This makes sure that practically no admixture in the shape of dust leaves the silo or the mixer and ends up in the environment.
Naturally, the invention is not restricted to the above-described embodiments of the mixer installation. It goes without saying that within the scope of the invention as defined by the claims several variants are possible.
Thus, it is possible, for example, that the silo frame contains only one or more than two silos. For example, the use of four silos can be considered when two different admixtures must be supplied to the mixer. In that case, two silos are used for each admixture, such that they can be refilled by turns and a continuous operation of the mixer installation is thus guaranteed.
Further, it is not necessary that all silos are supported by one and the same silo frame; a separate silo frame can be used for each silo.

Claims

Mobile mixer installation having a transport condition and a working condition, with a basic frame (1) with a supply side (2) and a delivery side (3) on which are provided a dosing device (4), at least one silo (5,6), a feed belt (7) and a mixer (8), whereby, in said working condition, an outlet (10) of the dosing device (4) opens on the supply side (2) above the feed belt (7) which opens at an inlet (12) of the mixer (8) having an output (13) on the delivery side (3), whereby an outlet (18,19) of said silo (5,6) also opens at the inlet (12) of the mixer (8), characterised in that said mixer (8) is hinge-mounted to the basic frame (1) on said delivery side (3) via a mixer pivot shaft (32), whereas the inlet (12) of the mixer (8) is hinge-mounted to the delivery end (33) of said feed belt (7), whereby the silo (5,6) is hinge-mounted, via a silo pivot shaft (36), to a first end (37) of a supporting arm (38) whose opposite second end (39) is hinge-mounted to the basic frame (1), whereby said silo (5,6) is put from the working condition into the transport condition by rotating said supporting arm (38) around the hinged connection on said second end (39) such that said first end (37) of the supporting arm (38) is moved to said supply side (2), whereby the silo (5,6) is moved to this supply side (2) into a lower position, while the mixer (8) of the working condition is moved into the transport condition by subjecting it to a rotation around the mixer pivot shaft (32) into a lower position.
Mixer installation according to claim 1, whereby said silo (5,6) cooperates with a silo weighing device.
Mixer installation according to claim 1 or 2, whereby it contains at least two separate silos (5,6) which are each equipped with a silo weighing device.
Mixer installation according to any one of the preceding claims, whereby said feed belt (7) comprises a belt weighing device.
Mixer installation according to any one of the preceding claims, whereby said silo (5,6) has at least one supporting member (40) on its supply side (2), one far end of which is fixed to said silo (5,6), whereas the opposite end of this supporting member (40) is led by a guide (41) when the silo (5,6) is being moved between the working position and the transport position, whereby this guide (41) is provided on said basic frame (1), such that its height increases as of the supply side (2) to the delivery side (3).
Mixer installation according to any one of the preceding claims, whereby said mixer (8) is supported in the working condition by an elongated upright support element (43) which is hinge-mounted to the mixer (8) with one far end, whereby the opposite end (44) of this support element (43) rests on a bearing surface (45) of the basic frame (1), while in said transport condition this support element (43) is rotated around the hinged end into an inclined or horizontal position.
Mixer installation according to any one of the preceding claims, whereby it contains a delivery conveyor belt (20) which extends as of the delivery side (3) of the basic frame (1), whereby the outlet (13) of said mixer (8) opens above said delivery conveyor belt (20) in said working condition.
Mixer installation according to claim 7, whereby said delivery conveyor belt (20) has a horizontal pivot shaft (29), such that a first part (30) of this delivery conveyor belt (20) can be moved around this pivot shaft (29) in relation to a second part (31) thereof.
Mixer installation according to any one of the preceding claims, whereby said feed belt (7) is suspended on the supply side (2) of the basic frame (1) by means of a cylindrical cam (34) which is fixed to the basic frame (1) of the feed belt (7) and which is guided in an elongated slot (31) provided in the feed belt (7) or the basic frame (1) respectively.
Mixer installation according to any one of the preceding claims whereby it contains at least one water tank (46,47) which is connected to the inlet (12) of said mixer (8).