WO2014057328A2

WO2014057328A2 - Process for preparing a mixture of stone dust with air for dusting excavations and excavations stone-duster

Info

Publication number: WO2014057328A2
Application number: PCT/IB2013/002193
Authority: WO
Inventors: Tomasz AWŁASEWICZ; Radosław KOWALEWSKI; Krzysztof STRYKIER
Original assignee: Auto-Hit S.A.
Priority date: 2012-10-03
Filing date: 2013-10-03
Publication date: 2014-04-17
Also published as: PL401043A1; WO2014057328A3

Abstract

The method involves the simultaneous supply into the mixing chamber (4) of stone dust and compressed air and the discharge of ready to use mixture. Stone dust from the hopper (3) is fed into the mixing chamber (4) by means of a horizontal screw feeder (2) through the inlet hole (28) with the flap valve (32). The mixing chamber (4) comprises a substantially vertical front wall (21), a substantially vertical rear wall (9) and side walls (22) parting from the bottom to the top. Compressed air is fed to the mixing chamber (4) through single inlet hole (29) situated in the lower part of the rear wall (9) of the mixing chamber (4). Screw feeder (2) has a screw (7) with a substantially constant outer diameter (D3) and inner diameter (D2), and with constant helix angle, which rotates in a horizontal tube guide (8) fixed to the rear wall (9) of the mixing chamber (4). The stone dust inlet hole (28) there is in the rear wall (9) of the mixing chamber (4) above the compressed air inlet hole (29). The surface area of the stone dust inlet hole (28) ranges from 30 to 43% of the cross-sectional area of the tube guide (8) of the screw feeder (2). The ready to use mixture of stone dust with air is discharged from the mixing chamber (4) via outlet (25) situated in the lower part of the front wall (21) opposite the of compressed air inlet hole (29).

Description

Process for preparing a mixture of stone dust with air for dusting excavations and excavations stone-duster

Technical Field

The presented invention relates to a process for preparing a mixture of stone dust with air for dusting excavations, and the excavations stone duster, designed to bind to dangerously explosive coal dust.

Background Art

The hazard of coal dust created during mining of coal is very well known. The coal dust, after mixing in the appropriate proportions with the air, forms a highly explosive gas mixture. Explosion of coal dust in the mine, in addition to the typical effects of any explosion, instantly increases the level of carbon monoxide in the air. For several decades to neutralize coal dust is used a mixture of stone dust with the air that is dusted with pit mining and which effectively binds the pulverized coal into not explosive condition.

GB 514946 discloses a device for mixing the pulverized stone with the compressed air and blowing the mixture on the walls of the mine. This device contains an elongated hopper, the bottom of which there is a screw rotatable mounted at both ends. After filling hopper with stone dust rotating screw moves the powder to the chamber which receives the compressed air and then the mixture of air and dust is discharged from the chamber to the selected location. In one of the variants of this device, compressed air enters the bottom of the inclined chamber in the middle of the length of which is supplied stone dust, and from the top is received in a chamber formed mixture. In another variant, to geometrically similar chamber stone dust is fed from the bottom, while the air supply special nozzle, whose outlet is located in the upper part of the chamber. In yet another variant of the solution chamber has a shape similar to the letter U. The pulverized stone is delivered to the centre of the chamber side, and compressed air through the vertical nozzle. US2489090 discloses a duster having a longitudinal hopper at the bottom of which is mounted screw feeder with the bearing on one side of the hopper. On the other side of the hopper screw feeder enter a tube guide closed with spring loaded valve. Surrounds the tube guide channel with compressed air, which grabs stone dust ejected by the feeder.

The duster nearest to the object of the invention is disclosed in GB634272. As in the previous solution, the feeding screw, which is located in the lower part of the hopper, is mounted on one side of the hopper. On the opposite side of the hopper screw enters a tube guide, which outlet is in the interior of the horizontal mixing chamber. Compressed air is supplied to the chamber with two oblique channels, having the outlet at the same level as the outlet of the feeding screw. Outlet of the screw feeder is provided with a flap valve which closes by gravity and opens towards the interior of the mixing chamber.

Disclosure of Invention

Object of the invention was to obtain structurally simple, yet sustainable and efficient source of air-stone powder mixture for pit mining dusting.

Such the object implements a method according to the invention comprising comprising the simultaneous supply of stone dust and air into the mixing chamber, and discharge of a ready to use mixture. The supplying of stone dust into the mixing chamber is realized by means of a horizontal screw feeder. Stone dust inlet hole for the mixing camber is provided with a flap valve closed by gravity and opened towards the interior of the mixing chamber. The supplying of the screw feeder with stone dust occurs by gravity from the top using a hopper. The method is characterized by that for mixing the stone dust with the air is used a mixing chamber which comprises a substantially vertical front wall, a substantially vertical rear wall and side walls parting from the bottom to the top, while the compressed air is fed to the mixed chamber through a single inlet hole situated in the lower part of the rear wall of the mixing chamber. For feeding the stone dust is used a screw feeder with a screw with a substantially constant outer diameter and inner diameter, and with constant helix angle, placed in a horizontal tube guide fixed to the rear wall of the mixing chamber. The stone dust supplied by the screw feeder is introduced to the mixing chamber through a stone dust inlet hole situated in the rear wall of the mixing chamber above the compressed air inlet. The surface area of the stone dust inlet hole ranges from 30 to 43% of the cross-section area of the guide of screw feeder. The ready to use mixture of the stone dust with air is discharged from the mixing chamber via outlet situated in the lower part of the front wall opposite of the compressed air inlet hole.

In one embodiment of the method according to the invention, the screw feeder is provided with a drive shaft coupled coaxially with the screw feeder. The shafts rotatable supported by two bearings located on the outside of the tube guide of the feeder. These bearings are located on the opposite side feeder than the mixing chamber. For supply stone dust is used a screw, whose outer diameter ranges from 90 to 97% of the inner diameter of the tube guide of the feeder, and the stone dust inlet hole whose lower part of its outline is tangent to the the lower part of outline of the cross section of the tube guide of the feeder (2).

In another embodiment of the invention the mixing chamber is fed with air at a pressure of at least 0.5 atmosphere and in an amount of at least 0.8 m³/min, and with stone dust having a particle size of not more than 1 mm in an amount at least 22 kg/min.

In another embodiment of the invention the rear end of the of screw feeder is sealed by means of a cylindrical sealing member with a spiral groove on its cylindrical surface, with a twist of the helix coinciding with a turn of the helix screw. Outer diameter of the cylindrical sealing member ranges from 101 to 105% of the inner diameter of the tube guide (8) and its length ranges from 85 to 100% of the outer diameter of this member. The cylindrical sealing member is connected coaxially to the end of the screw and located in a cylindrical enlargement of the rear end of the tube guide with a diameter ranging from 102 to 106% of the outside diameter of the cylindrical sealing member.

In another embodiment of the invention the drive shaft of the screw feeder is rotated by a pneumatic motor powered from a compressed air source, from which the mixing chamber is also fed.

In another embodiment of the invention the drive shaft of the screw feeder is rotated by a twin shaft hydraulic motor. A second shaft of the motor drives an air blower, being a source of the compressed air supplied into the mixing chamber. In another embodiment of the invention the drive shaft of the screw feeder is rotated by a twin shaft electric motor. A second shaft of the motor drives an air blower, being a source of the compressed air supplied into the mixing chamber. In yet another embodiment of the invention the drive shaft of the screw feeder is rotated by a hydraulic motor with its axis of rotation parallel to the axis of rotation of the drive shaft. Transmission from the hydraulic motor to the drive shaft is done via a gear located between the bearings supporting the shaft. The free end of the drive shaft drives an air blower, being a source of the compressed air supplied into the mixing chamber.

Duster according to the invention the present invention comprises a mixing chamber for mixing of air with stone dust, horizontal screw feeder with a hopper supplying by gravity from the top the screw feeder with the stone dust. Supplying the stone dust to the mixing chamber take place through inlet hole with the flap valve closed by gravity and opened towards the interior of the mixing chamber. The duster is characterized by that the mixing chamber comprises a substantially vertical front wall, a substantially vertical rear wall and side walls parting from the bottom to the top. The screw feeder consists of a horizontal tube guide fixed to the rear wall of the mixing chamber and of rotating inside said guide a screw with a substantially constant outer diameter and inner diameter and with constant helix angle. In the lower part of the rear wall of the mixing chamber there is an inlet hole for the compressed air for the mixing chamber. A stone dust inlet hole with the flap valve is situated in the rear wall of the mixing chamber above the compressed air inlet hole. The surface area of the stone dust inlet hole ranges from 30 to 42% of the cross-section area of the tube guide of the screw feeder. In the lower part of the front wall of the mixing chamber, opposite the compressed air inlet hole, there is an outlet for ready to use mixture of stone dust with air.

In one embodiment of the duster according to the invention the screw feeder has a drive shaft connected coaxially with the screw of the feeder. The drive shaft is rotationally supported by two bearings located on the outside of the tube guide of the feeder, on the opposite side of the tube guide (8) than of the mixing chamber. The outer diameter the screw ranges from 90 to 97% of the inner diameter of the tube guide. The lower part of the outline of the stone dust inlet hole is tangent to the lower part of the cross-section outline of the tube guide of the feeder.

In another embodiment of the duster according to the invention the flap valve opening angle does not exceed 42°.

In a further embodiment of the duster according to the invention the rear end of the of screw feeder is sealed by means of a cylindrical sealing member with an outer diameter ranging from 101 to 105% of the internal diameter of the tube guide and with a length ranging from 85 to 100% of the outer diameter of this member. The cylindrical sealing member is connected coaxially to the end of the screw, its cylindrical surface has a helical groove with a twist of the helix coinciding with a turn of the helix of the screw and is located in a cylindrical enlargement of the rear end of the tube guide with a diameter ranging from 102 to 106 % of the outside diameter of the cylindrical sealing member.

In a further embodiment of the duster according to the invention the drive shaft of the screw feeder is linearly coupled with a pneumatic motor.

In another embodiment of the duster according to the invention the drive shaft of the screw feeder is linearly coupled with a two-shaft hydraulic motor, the second shaft of which is linearly coupled with an air blower, which is a source of the compressed air supplied into the mixing chamber.

In another embodiment of the duster according to the invention the drive shaft of the screw feeder is linearly coupled with a twin shaft electric motor, the second shaft of which is linearly coupled with an air blower, which is a source of the compressed air supplied into the mixing chamber.

In yet another embodiment of the duster according to the invention the drive shaft of the screw feeder is coupled with a hydraulic motor with axis of rotation parallel to the axis of rotation of the drive shaft of the feeder. The coupling is realized via a gear located between the bearings supporting the shaft. The free end of the drive shaft is linearly coupled with an air blower which is a source of the compressed air supplied into the mixing chamber.

The invention allows for obtaining a homogeneous mixture of stone dust and air with parameters to ensure effective bonding of coal dust even after transporting the mixture by a flexible pipe with a length of 60 meters. Possibility to use hoses of different lengths provides precise coating of stone dust on the walls of the excavation, together with reducing operating times. Duster according to the invention has a simple structure and low susceptibility to damage. The ability to work of screw feeder and mixing chamber with any drive allows you to run dusting pits regardless of the type of media available in the mine, and the compact design allows you to use the duster even in tight and hard to reach areas. Using of screw with constant cross-section eliminates the risk of blocking the feed stone dust as a result of accidentally getting into the hopper of small stones or other small foreign objects.

Brief Description of Drawings

The invention is schematically shown in the embodiment in the drawing, in which Fig. 1 shows a perspective view of the duster according to the invention. Fig. 2 shows a section of a vertical plane through a screw feeder and a mixing chamber. Figures 3, 4 , 5, 6 , 7 and 8 show the body of the screw feeder respectively in a perspective view, top view, side view, vertical plane cross-section and the front and rear views. Figures 9, 10 and 11 show the screw feeder respectively in a perspective view, side view and in longitudinal section. Figures 12, 13 , 14 and 15 show the front portion of the mixing chamber respectively in a perspective view, front view, side view and in vertical plane cross-section. Fig.16 and Fig. 17 show the flap valve, respectively in a perspective view in an open state and a vertical section of the closed valve. In order to provide greater clarity is not drawn to the same scale for all figures. Figures 18, 19 and 20 are block diagrams of different variants of drive of the duster according to the invention.

Mode for Carrying out Invention

Exemplary duster according to the invention has welded steel base member 1 , on which are mounted screw feeder 2 with hopper 3 and the mixing chamber 4, air blower 5, not shown the engine of the drive and control-steering components. Screw feeder 2 consists of a steel welded body 6 and screw 7. The body 6 is a tube guide 8 of a length L of 470mm and of an inner diameter D1 of 81 .6mm. To the front of the tube guide 8 is welded perpendicularly to its axis the rear wall 9 of the mixing chamber 4, which constitutes at the same time the front support of body 6. In the upper portion of the guide 8 there is a pour cut 10 starting about half of the length of the guide 8 measuring from its front and extending over a length of about 35% of the total length L of the guide 8. The pour cut 10 is surrounded by a lower part 3' of the of the hopper 3, finished at the top with the rectangular flange 11. To the flange 11 is fastened by bolts upper (wider) part 3" of the hopper 3. The guide 8 has in the rear of the two supports 12. Right-hand feeder screw 7 has a shaft 13 and a screw element 14 form an integral whole. The diameter D2 of the shaft 13 of the screw 7 is 30 mm, outer diameter D3 of the screw is 76 mm, and the pitch of the screw portion 14 is 48 mm. On the rear end of the shaft 13 is mounted sealing-coupling cylindrical member 15 with an outer diameter D4 of 88 mm and a length of 78 mm. In the cylindrical member 15 is nonrotatably mounted (with the groove 16) drive shaft 17 of the screw feeder 2. The shaft 17 is supported by two bearings 18 fixed to the base 1 of duster. Cylindrical member 15 has on its cylindrical surface a right-hand helical groove 19 width of 3 mm and a pitch of 6 mm. After placing the screw 7 in the tube guide 8 the cylindrical member 15 is located in the enlaged portion 8' of the tube guide 8 having an inner diameter D5 of 92 mm. The grooved cylindrical member 15 forms with the widened portion 8' of the guide 8 a shaped seal. Mixing chamber 4 form the rear wall 9 and a front body 20 fastened with screws to the wall. The front body 20 constitute a substantially vertical front wall 21 , two side walls 22 parting from the bottom to the top at an angle of about 34 degrees as well as curved bottom wall 23 and curved top wall 24, respectively connecting the lower and upper ends of the side walls 22. The bottom wall 23 is a portion of tube outlet 25 from the chamber 4. At the outlet 25 there is mounted a stub pipe 26 of - not shown in the drawing - hose discharging the mixture of stone dust with air produced in the chamber 4. The side walls 22, bottom wall 23 and top wal 24 are surrounded by a fastening flange 27 located on the opposite side of the wall than the front wall 21. The mixing chamber 4 has a stone dust inlet hole 28, a compressed air inlet hole 29 and an outlet hole 30 for mixture of stone dust with air. The stone dust inlet hole 28 having D6 diameter of 50 mm and a compressed air inlet hole 29 having a diameter 56 mm are located in the rear wall 9 of the mixing chamber 4 and are located one above the other. Compressed air is supplied to the inlet hole 29 by conduit not shown in the drawing and fitted on a stub pipe 31. The outlet hole 29 of the prepared mixture is located in the lower part of the front wall 21 of the mixing chamber 4, opposite the compressed air inlet hole 29. The lower part of the outline of the stone dust inlet hole 28 is tangent (Fig. 8) to the lower part of the outline of the cross section of the tube guide 8 of the screw feeder 2. The stone dust inlet hole 28 is provided with a with a flap valve 32 consisting of a seat 33 surrounding the inlet hole 28 and of a flap 34 closed by gravity and opened towards the interior of the mixing chamber 4. The opening angle of the flap 34 does not exceed 42° and this restriction is a consequence of the dimensions of the valve 32 and its distance from the front wall 21 of the front body 20. The drive shaft 17 of the screw feeder 2 can be rotated by different engines. In one embodiment of the invention, the shaft 17 is rotated by a pneumatic vane motor 35, powered by compressed air source 36, from which the compressed air is delivered to the mixing chamber 4. In another embodiment of the invention the drive of the screw feeder 2 is implemented as a twin shaft motor 37, electric or hydraulic. The first shaft 38 of the motor 37 is coupled linearly with the drive shaft 17 of the feeder 2. The second shaft 39 of the motor 37 is linearly coupled with an air blower 5, which is a source of the compressed air supplied to the mixing chamber 4. In yet another embodiment of the duster according to the invention the drive shaft 17 of the screw feeder 2 is rotated by a one shaft hydraulic motor 40 - gerotor or toothed. The motor 40 axis of rotation is parallel to the axis of rotation of the drive shaft 17. Transmission from the hydraulic motor 40 to the shaft 17 is carried out via a belt drive 41 cooperating with the pulley 42 located at the shaft 17 between the bearings 18 supporting the shaft 17. The free end of the shaft 17 drives the air blower 5 which is a source of the compressed air supplied to the mixing chamber 4.

The mixing chamber 4 is fed with the compressed air at a pressure of at least 0.5 atmosphere and in an amount of at least 0.8 m³/min. The speed of rotation of feeder screw 7 is adjusted so the stone dust with a grain size of less than 1 mm poured into the hopper 3 reaches the mixing chamber 4 in an amount of at least 22 kg/min.

Claims

1. A method for preparing a mixture of stone dust with the air for dusting excavations, comprising the simultaneous supply of stone dust and air into the mixing chamber, and discharge of a ready to use mixture, wherein the supplying of stone dust into the mixing chamber is realized by means of a horizontal screw feeder through the inlet hole provided with a flap valve closed by gravity and opened towards the interior of the mixing chamber, while the supplying of the screw feeder with stone dust occurs by gravity from the top using a hopper, characterized in that to mix the stone dust with the air is used a mixing chamber (4) which comprises a substantially vertical front wall (21), a substantially vertical rear wall (9) and side walls (22) parting from the bottom to the top, the compressed air is fed to the mixed chamber (4) through a single inlet hole (29) situated in the lower part of the rear wall (9) of the mixing chamber (4), for feeding the stone dust is used a screw feeder (2) with a screw (7) with a substantially constant outer diameter (D3) and inner diameter (D2), and with constant helix angle, placed in a horizontal tube guide (8) fixed to the rear wall (9) of the mixing chamber (4), wherein the stone dust supplied by the screw feeder (2) is introduced to the mixing chamber (4) through a stone dust inlet hole (28) situated in the rear wall (9) of the mixing chamber (4) above the compressed air inlet (29), the surface area of the stone dust inlet hole (28) ranges from 30 to 43% of the cross-sectional area of the guide (8) of screw feeder (2), while the ready to use mixture of the stone dust with air is discharged from the mixing chamber (4) via outlet (25) located in the lower part of the front wall (21) at the height of the compressed air inlet hole (29).

2. The method according to claim 1 , characterized in that the screw feeder (2) is provided with a drive shaft (17) connected coaxially with the screw (7) of the feeder (2), wherein the shaft (17) is rotatable supported by two bearings (18) located on the outside of the tube guide (8) of the feeder, on its side opposite the mixing chamber (4), while for stone dust feeding is used screw (7) whose outer diameter (D3) ranges from 90 to 97% of the inner diameter (D1) of the tube guide (8) of the feeder (2), and the stone dust inlet hole (28) whose lower part of its outline is tangent to the the lower part of outline of the cross section of the tube guide (8) of the feeder (2).

3. The method according to claim 1 or 2, characterized in that the mixing chamber (4) is fed with air at a pressure of at least 0.5 atmosphere and in an amount of at least 0.8 m³/min, and with stone dust having a particle size of not more than 1 mm in an amount at least 22 kg/min.

4. The method according to claim 1 or 2 or 3, characterized in that the rear end of the of screw feeder (2) is sealed by means of a cylindrical sealing member (15) with a spiral groove (19) on its cylindrical surface, with a twist of the helix coinciding with a turn of the helix screw, wherein the outer diameter (D4) of the cylindrical sealing member (1.5.) ranges from 101 to 105% of the inner diameter (D6) of the tube guide (8) and its length ranges from 85 to 100% of the outer diameter (D4) of this member (15), the cylindrical sealing member ( 5) is connected coaxially to the end of the screw (7) and located in a cylindrical enlargement (8') of the rear end of the tube guide (8) with a diameter (D5) ranging from 102 to 106 % of the outside diameter (D4) of the cylindrical sealing member (15).

5. The method according to claim 2 or 3 or 4, characterized in that the drive shaft (17) of the screw feeder (2) is rotated by a pneumatic motor (35) powered from a compressed air source (36), from which the mixing chamber (4) is fed.

6. The method according to claim 2 or 3 or 4, characterized in that the drive shaft (17) of the screw feeder (2) is rotated by a twin shaft hydraulic motor (37), and a second shaft (39) of the motor (37) drives an air blower (5), being a source of the compressed air supplied into the mixing chamber (4).

7. The method according to claim 2 or 3 or 4, characterized in that the drive shaft (17) of the screw feeder (2) is rotated by a twin shaft electric motor (37), and a second shaft (39) of the motor drives an air blower (5), being a source of the compressed air supplied into the mixing chamber (4).

8. The method according to claim 2 or 3 or 4, characterized in that the drive shaft (17) of the screw feeder (2) is rotated by a hydraulic motor (40) with its axis of rotation parallel to the axis of rotation of the drive shaft (17), transmission from the hydraulic motor (40 ) to the drive shaft (17) is done via a gear (41) located between the bearings ( 8) supporting the shaft (17), wherein the free end of the drive shaft (17) drives an air blower (5), being a source of the compressed air supplied into the mixing chamber (4).

9. An excavations stone duster comprising a mixing chamber for mixing of air with stone dust, horizontal screw feeder with a hopper supplying by gravity from the top the screw feeder with the stone dust, and with inlet hole with the flap valve closed by gravity and opened towards the interior of the mixing chamber, characterized in that the mixing chamber (4) comprises a substantially vertical front wall (21), a substantially vertical rear wall (9) and side walls (22) parting from the bottom to the top, the screw feeder (2) consists of a horizontal tube guide (8) fixed to the rear wall (9) of the mixing chamber (4) and of rotating inside said guide (8) a screw (7) with a substantially constant outer diameter (D3) and inner diameter (D2), and with constant helix angle, in the lower part of the rear wall (9) of the mixing chamber (4) there is an inlet hole (29) for the compressed air for the mixing chamber (4), a stone dust inlet hole (28) with the flap valve (32) is situated in the rear wall (9) of the mixing chamber (4) above the compressed air inlet hole (29), the surface area of the stone dust inlet hole (28) ranges from 30 to 42% of the cross-sectional area of the tube guide (8) of the screw feeder (2), while in the lower part of the front wall (21) of the mixing chamber (4), opposite the compressed air inlet hole (29), there is an outlet (25) for ready to use mixture of stone dust with air.

10. The duster according to claim 9, characterized in that the screw feeder (2) has a drive shaft (17) connected coaxially with the screw (7) of the feeder (2), wherein the drive shaft (17) is rotationally supported by two bearings (18) located on the outside of the tube guide (8) of the feeder (2), on the opposite side of the tube guide (8) than of the mixing chamber (14), the outer diameter (D3) the screw (7) ranges from 90 to 97% of the inner diameter (D1) of the tube guide (8) and the lower part of the outline of the stone dust inlet hole (28) is tangent to the lower part of the cross-section outline of the tube guide (8) of the feeder (2)

11. The duster according to claim 9 or 10, characterized in that the flap valve (32) opening angle does not exceed 42°.

12. The duster according to claim 9 or 10 or 11 , characterized in that the rear end of the of screw feeder (2) is sealed by means of a cylindrical sealing member (15) with an outer diameter (D4) ranging from 101 to 105% of the internal diameter (D1) of the tube guide and with a length ranging from 85 to 100% of the outer diameter (D4) of this member (15), wherein the cylindrical sealing member (15) is connected coaxially to the end of the screw (7), on its cylindrical surface has a helical groove (19) with a twist of the helix coinciding with a turn of the helix of the screw and is located in a cylindrical enlargement (8') of the rear end of the tube guide (8) with a diameter (D5) ranging from 102 to 106 % of the outside diameter (D4) of the cylindrical sealing member (15).

13. The duster according to claim 10 or 11 or 12, characterized in that the drive shaft ( 7) of the screw feeder (2) is linearly coupled with a pneumatic motor (35).

14. The duster according to claim 0 or 1 or 12, characterized in that the drive shaft (17) of the screw feeder (2) is linearly coupled with a two-shaft hydraulic motor (37), the second shaft of which (39) is linearly coupled with an air blower (5), which is a source of the compressed air supplied into the mixing chamber (4).

15. The duster according to claim 10 or 11 or 12, characterized in that the drive shaft (17) of the screw feeder (2) is linearly coupled with a twin shaft electric motor (37), the second shaft of which (39) is linearly coupled with an air blower (5), which is a source of the compressed air supplied into the mixing chamber (4).

16. The duster according to claim 10 or 11 or 12, characterized in that the drive shaft (17) of the screw feeder (2) is coupled with a hydraulic motor (40) with axis of rotation parallel to the axis of rotation of the drive shaft (17) via a gear (41) located between the bearings (18) supporting the shaft (17) and the free end of the drive shaft (17) is linearly coupled with an air blower (5), which is a source of the compressed air supplied into the mixing chamber (4).