SEED TREATMENT METHOD

Abstract

A seed treatment method, using a composition obtained extemporaneously by mixing at least one powder substance and an aqueous medium, comprising the steps consisting of: producing the mixture in an automatic and cyclic manner, in at least one first vessel (10; 10), by introducing into same first at least a portion of the aqueous medium and next the powder substance, the latter being sucked into the aqueous medium in the vessel by means of a vacuum created in the vessel, at least partially draining the content of the vessel, by means of at least one blast of compressed gas in the vessel, to a seed treatment device where the mixture is brought into contact with the seeds.

Claims

1. A seed treatment process, using a composition obtained extemporaneously by mixing at least one pulverulent substance and an aqueous medium, comprising the steps consisting in: automatically and cyclically carrying out the mixing in at least a first tank by introducing into said tank first at least one portion of the aqueous medium and then the pulverulent substance, the latter being sucked into the aqueous medium in the tank by virtue of a negative pressure created in the tank, at least partially emptying its content to a seed treatment device where the mixture is brought into contact with the seeds, said emptying being carried out by means of at least one blast of a compressed gas in the tank.

2. The process as claimed in claim 1, wherein the pulverulent substance is a hydratable compound.

3. The process as claimed in claim 1, wherein the volume of the mixture in the tank is less than or equal to 15 l.

4. The process as claimed in claim 1, wherein the first blast is carried out at the latest 60 s after the end of the introduction of the pulverulent substance into the tank and the final blast is carried out, where appropriate, at the latest 30 min after the end of the introduction of the pulverulent substance into the tank.

5. The process as claimed in claim 1 wherein the injection of the pulverulent substance into the tank is carried out through a tapping with an internal diameter of less than or equal to 17 mm.

6. The process as claimed in claim 5, wherein the mixture is subjected to stirring according to a condition that is weaker at the time of the at least partial emptying, compared with the sequence going from the beginning of the introduction of the pulverulent substance to the beginning of the emptying.

7. The process as claimed in claim 1, wherein the minimum level of negative pressure in the tank just before the suctioning of the pulverulent substance is between ?0.05 and ?1 bar.

8. The process as claimed in claim 7, wherein the minimum level of negative pressure is maintained in the tank throughout the injection of the pulverulent substance.

9. The process as claimed in claim 1, wherein the level of overpressure in the tank during the at least partial emptying operation is between 0.05 and 2 bar.

10. The process as claimed in claim 1, wherein the discharging of the content of the tank is carried out at the latest 5 min after the end of the introduction of the pulverulent substance into the tank.

11. The process as claimed in claim 1, wherein the hydration resulting from the application of the content of the tank on the seeds is sufficiently low for the treated seeds to be able to neither agglomerate nor germinate during their storage.

12. A facility for preparing a seed treatment composition, said facility comprising at least one tank comprising: at least one tapping located below the level of the aqueous medium in the tank, where appropriate taking into account the vortex from stirring the aqueous medium, and connected to a pulverulent substance feed, one or more tappings connected to a tank water feed pipe, this pipe itself comprising one or more tappings allowing injection of active agent(s) into said pipe, a vent, a vacuum source, a compressed air source, and an outlet for emptying the tank to a treatment device where the mixture is brought into contact with the seeds to be treated.

13. The facility as claimed in claim 12, comprising a washing head in the tank, connected to the tank water feed pipe by means of a bypass.

14. The facility as claimed in either of claim 12, wherein the tank has a volume of less than or equal to 50 l, and a volume of greater than or equal to 0.1 l.

15. The facility as claimed in claim 12, comprising an automated device for controlling solenoid valves, motors and/or pumps making it possible to cyclically control the filling, including the metering, of the tank with liquid, the metering and then the injection of the pulverulent substance into the tank, the emptying of the tank, and the stirring in said tank.

Description

[0107] A nonlimiting example of implementation of the invention will now be described, with reference to the appended drawing, in which

[0108] FIGS. 1 to 4 represent a treatment facility according to the invention, and

[0109] FIG. 5 represents a detailed implementation of a pulverulent substance feed tapping variant.

DETAILED DESCRIPTION

[0110] The process according to the invention may be carried out using a facility as represented diagrammatically in FIGS. 1 to 4.

[0111] This facility comprises at least one preparation tank 10 and, better still, as illustrated in FIGS. 1 and 2, two tanks 10 and 10.

[0112] Each tank 10 or 10 preferably has a volume of less than or equal to 50 l, better still less than or equal to 20 l, even better still less than or equal to 10 l, and a volume of greater than or equal to 0.1 l, better still greater than or equal to 0.5 l, even better still greater than or equal to 1 l.

[0113] Each tank 10 or 10 has various tappings 11 to 14 in the upper part, and a tapping 15 on the side wall.

[0114] In the example in question, each tank 10 and 10 is for example made of stainless steel that may comprise for example an internal coating of Teflon type and comprises a cylindrical body 16 closed in the lower part by a conical bottom wall 17 and in the upper part by a cover 19.

[0115] A stirring device 23 is associated with each tank 10 and 10, this device comprising a shaft 22 which is driven to rotate on itself by a motor 20. One or more mixing members 21, which may be identical or different, are mounted on the shaft 22 in such a way as to be driven rotationally by said shaft.

[0116] The mixing member(s) 21 may be in particular selected from deflocculation devices or stirrers of Intermig type.

[0117] The tapping 12 feeds at least one nozzle for spraying rinsing water at 60-360? into the tank. In the example in question, the tapping 12 feeds a rotating pulverization ball 24.

[0118] The tapping 12 is connected, by means of a solenoid valve 50, to a pipe 25 fed by a water network 27, for example mains network, represented in FIG. 4.

[0119] As is seen in this FIG. 4, the pipes 25 connected to the tappings 12 of the two tanks 10 and 10 join together downstream of a section 40 supporting various active substance feed tappings 30 to 34, these tappings being for example placed close together according to a clarinet assembly.

[0120] Returning to FIGS. 1 and 2, it is seen that the tapping 13 of each tank 10 or 10 is connected, by means of a bypass 42 comprising a solenoid valve 51, to the corresponding pipe 25, upstream of the solenoid valve 50 and downstream of the section 40.

[0121] Each tapping 14 is connected, on the one hand, by means of a solenoid valve 54, to a vent 55 and, on the other hand, to a compressed air source 57, by means of a solenoid valve not represented. The tappings 11 of the tanks 10 and 10 are connected, each by means of a solenoid valve 58, to a vacuum source 59, in particular comprising a Venturi.

[0122] According to one embodiment, each tapping 14 may be connected at the same time to a vent 55 by means of a solenoid valve 54, to a compressed air source 57 by means of a solenoid valve not represented and to a vacuum source 59 in particular comprising a Venturi, by means of a solenoid valve 58. Such an embodiment makes it possible in particular to reduce the bulkiness of the facility.

[0123] The tappings 30 to 34 of the section 40 are connected, by means of respective solenoid valves 60 to 64, to sources of active agents that may be present in the final mixture.

[0124] The tappings 30 to 34 may be fed by metering pumps through respective flowmeters 70 to 74 which make it possible to accurately know the amount of active agent dispensed.

[0125] Alternatively, the flowmeters 70 to 74 are not considered to be part of the facility according to the invention, these flowmetres possibly in fact being pre-existing and linked to the metering pumps.

[0126] The section 40 may be fed selectively by a compressed air network 82 or by the mains water network 27, by means of solenoid valves 80 and 81, respectively.

[0127] Each tapping 15 opens out into the corresponding tank 10 10, below the nominal level of the liquid in the tank during the mixing operation. This means that each tapping 15 opens out into the corresponding tank 10 or 10, below the level of the liquid in the tank, taking into account where appropriate the stirring vortex. This allows the injection of the pulverulent substance below the level of liquid.

[0128] The tapping 15 opens out for example, as illustrated, substantially at the junction between the cylindrical body 16 of the tank and its bottom wall 17.

[0129] The tapping 15 may, as illustrated in FIGS. 1 and 2, be oriented substantially horizontally or, as illustrated in FIG. 5, be oriented with a non-zero angle a to the horizontal. The tapping 15 is for example oriented obliquely downward, in particular at 45? relative to the axis of the tank. In this case, it will preferably open out on the cylindrical body 16. The tapping 15 may also be oriented obliquely upward. In this case, it will preferably open out on the bottom wall 17. Preferably, the tapping 15 is oriented obliquely downward, in particular at 45? relative to the axis of the tank.

[0130] The tapping preferably has an internal diameter of less than or equal to 17 mm, for example of between 3 and 17 mm, better still of between 5 and 15 mm.

[0131] Each tapping 15 is connected via a solenoid valve 95 to a pipe 100 for introducing the pulverulent substance into the tank 10 or 10. This pipe 100 is connected, as illustrated in FIG. 3, to a powder metering system 122 which includes a hopper 120 feeding a powder transfer system 105 of worm screw (for example twin screw) or vibrating plate type, all of this optionally being mounted on a weigh scale 121 in order to know, by the difference, the amount delivered.

[0132] According to one embodiment, each tank 10 or 10 may also be mounted on a weigh scale (not represented) in order to measure the amount of liquid and/or of pulverulent substance which is introduced therein.

[0133] The pipe 100 is advantageously made up, or at least one portion of its length, of a flexible hose 106, which is preferably at least partially transparent. This facilitates maintenance in the event of clogging of the pipe 100.

[0134] Compressed air may be injected into the section between the solenoid valve 95 and the powder feed container 123, by means of a solenoid valve (not represented), connected to a compressed air network (not represented), in order to flush the pipe 100 between two introductions of pulverulent substance. Compressed air may also be continuously injected into the section between the solenoid valve 95 and the corresponding tank 10 or 10, in order to limit the liquid rising up into this section.

[0135] The solenoid valve 95 preferably comprises a tap of the full-bore globe type, the outlet pipe which may be attached a short distance away on the wall of the tank so as to limit the dead volume.

[0136] In the embodiment according to which the tapping 15 is oriented substantially horizontally, as illustrated in FIGS. 1 and 2, the solenoid valve 95 may be of piston type.

[0137] The discharging of the content of each tank 10 or 10 is carried out by means of an emptying orifice 126 at the bottom point of the bottom wall 17, this orifice opening out, by means of a solenoid valve 130, onto a discharge pipe 135. The solenoid valve 130 is preferably equipped with a globe-type tap.

[0138] The pipe 135 is connected to a three-way solenoid valve 140, which makes it possible to selectively connect the pipe 135 either to a waste collection container 145, or to a pipe 150 for feeding a training device, such as a coating machine, not represented on the drawing. Preferably, as illustrated, the connection of the solenoid valve 140 to the container 145 and to the treatment device is carried out by means of flexible hoses 147 and 148, respectively, advantageously made of stainless steel braided PTFE, which facilitates discharging the dispersion. An anti-drop valve (not represented) may be installed at the end of the flexible hose 148.

[0139] The three-way solenoid valve 140 is preferably equipped with a globe-type tap.

[0140] A nonintrusive flowmeter (not represented) may be placed downstream of the three-way solenoid valve 140 (that is to say between the seed treatment device and the three-way solenoid valve 140) for controlling said valve in order to interrupt the emptying of the corresponding tank 10 or 10 at the end of each cycle of feeding the treatment device by means of one of the tanks. The flowmeter makes it possible to know the amount of mixture sent to the treatment device. This nonintrusive flowmeter is not required when the content of the tank is totally emptied by means of a single blast of a compressed gas.

[0141] Compressed air may be injected into the section between the solenoid valves 130 and 140 by means of a solenoid valve 170, connected to the compressed air network, in order to flush the pipes at the end of use.

[0142] The shaft 22 of the stirring device may be centered or off-center relative to the axis of the tank.

[0143] The facility operates in the following way. The various solenoid valves, pumps and motors are controlled by an automated device. The latter automated device receives information from various sensors of the facility, in particular pressure, flow and weight sensors.

[0144] The tanks 10 and 10 are preferably used in parallel, in a phase-shifted manner, with preparation, in parallel, of the mixture in one of the tanks while the mixture contained in the other tank is sent to the treatment device, and conversely. In the following text, the process is described for the tank 10 only, since it is the same for the tank 10 in a time-shifted manner.

[0145] The tank 10 is first fed with active agents by the tapping 13, then with water by the tapping 12, and the level of liquid in the tank corresponds to a predefined amount which depends on the final concentration to be obtained of pulverulent material in the mixture. This level of liquid is sufficient for the tapping 15 to be immersed, where appropriate taking into account the stirring vortex. The volume of the mixture is preferably less than or equal to 15 l, better still less than or equal to 10 l. During the filling, the solenoid valve 54 is open, in order to open the communication to the vent 55. The water feed via the washing head 24 makes it possible to clean away from the emerging portion of the tank, any deposits left by the previous preparation cycle.

[0146] Then, the solenoid valves 50, 51 and 54 being closed, the solenoid valve 58 is opened, so as to place the tank under negative pressure via the tapping 11. Once the sufficient level of negative pressure has been reached, the solenoid valve 95 is opened so as to allow the injection of at least one pulverulent substance previously weighed and stored in the powder feed tank 123 below the level of liquid, where appropriate taking into account the vortex from stirring the latter during the injection. The minimum level of negative pressure in the tank just before the suctioning of the pulverulent substance is preferably between ?0.05 and ?1 bar, in particular between ?1 and ?0.8 bar, better still between ?0.3 and ?0.5 bar. Such a level of negative pressure allows satisfactory suctioning of the pulverulent substance while at the same time preventing the latter from being suctioned too violently and from passing through the liquid to the cover, which would cause foul of the emerging walls and the emission of dust. During the injection of pulverulent substance, the negative pressure is maintained at a sufficient value. The mixture is then subjected to stirring according to a first condition.

[0147] Next, the solenoid valves 58 and 95 are closed, and the mixture is subjected to a second stirring condition. This second condition is stronger, typically by a factor of 1.1 to 4, than the first. This second condition may be prolonged until the beginning of the emptying of the tank 10.

[0148] Once the mixture is ready to be sent to the seed treatment device, which is for example a coating machine, compressed air is sent via the tapping 14 and then the solenoid valve 130 is opened.

[0149] Once the anticipated amount has been delivered, the solenoid valve 130 is closed.

[0150] The mixture may be subjected, during the discharging of the tank 10, to stirring according to a third condition which is weaker, typically by a factor of 0.05 to 0.9 (or even zero), than the second.

[0151] The total emptying of the content of the tank may be carried out either by means of a single blast of a compressed gas, or by means of several consecutive blasts of a compressed gas. Preferably, the total emptying of the contents of the tank is carried out by means of a single blast of a compressed gas.

[0152] The discharging of the content of the tank may thus be carried out batchwise, in order to avoid too great an afflux of mixture to the treatment device. In this case, the solenoid valve 130 is opened at intervals.

[0153] The first blast may be carried out at the latest 60 s after the end of the introduction of the pulverulent substance into the tank, better still at the latest 30 s after said introduction, and the final blast may be carried out, where appropriate, at the latest 30 min after the end of the introduction of the pulverulent substance into the tank, better still at the latest 15 min after said introduction, even better still at the latest 5 min after said introduction and even better still at the latest 75 s after said introduction, or even at the latest 60 s after said introduction.

[0154] The level of overpressure in the tank 10 during the at least partial emptying operation is preferably between 0.05 and 2 bar, in particular between 0.1 and 1 bar. For example, the level of overpressure in the tank during the at least partial emptying operation may be less than or equal to 0.5 bar, for example between 0.1 and 0.5 bar.

[0155] When the emptying of the tank is fractionated, that is to say when it is carried out by several consecutive blasts of a compressed gas, the volumes emptied out during each blast may be identical or different. These volumes are determined according to the amount of seeds to be treated.

[0156] Once the tank 10 has been substantially emptied, the next preparation cycle may be started, while the mixture prepared in the tank 10 may be sent to the seed treatment device.

[0157] Of course, the invention is not limited to the example which has just been described.

[0158] The facility may comprise just one preparation tank, or, as a variant, more than two tanks.

[0159] The facility may also be used, where appropriate, for preparing a mixture without pulverulent substance, by introducing one or more active agents via the tappings 30 to 34, and by optionally mixing them with water sent to the tank 10 or 10.

[0160] Several powder metering systems may be used to feed the tank with different pulverulent substances. Thus, the mixture may comprise different pulverulent substances.