RU2681328C1 - Rotary drum-type furnace - Google Patents

Abstract

FIELD: heating.

SUBSTANCE: invention relates to a rotary drum-type furnace with a small slope, heated from the outside, for processing mineral and/or man-made ores or concentrates with fluoride and/or ammonium hydrofluoride during the processing of titanium-containing raw materials. Rotary drum-type furnace contains a body insulated from the inside, mounted on racks. Body is made in the form of a parallelepiped and rigidly fixed on the frame. Thermal insulation material is placed on the inner surface of the case, a hollow frame is installed on the thermal insulation material. Drum is cylindrical and mounted on a frame with bearings. Balls and two metal rods are placed in the drum. One end of the drum protrudes from the body and is inserted into the box, the screw feeder is inserted into the end of the drum through the box and the hole in the end of the drum. Box above is equipped with the main pipe for removal of gaseous products, and from the bottom - the pipe for unloading fine solid reaction products, carried away countercurrent from the drum. Shaft protruding from the body is welded to the other end of the drum. End of the shaft through the gearbox connected to the engine. Portion of the drum surface on the shaft side is made with perforations and is placed inside the intermediate box, which is connected to the bottom with a collection of solid reaction products, and is provided with a pipe for discharging gaseous reaction products from above.

EFFECT: prevents the loading mixture from setting with the inner wall of the drum in the heating process, heating the raw material directly through the wall of the drum.

1 cl, 1 dwg

Description

The invention relates to heating furnaces, namely to rotary drum furnaces with a small slope, heated from the outside, and can be used in the chemical processing of mineral or man-made materials containing non-ferrous metals, for example, by processing mineral and / or technogenic ores or concentrates with fluoride and / or ammonium hydrofluoride in the processing of titanium-containing raw materials.

Known rotary kiln for processing fine material [SU 478169 A1, IPC F27B 7/00, F28B 3/18, publ. 07/25/1975], containing an inclined cylindrical body, provided inside with a perforated spiral nozzle, a device for loading and unloading material and coolant. The furnace has a lined rotary drum lined from the inside with bandages and a drive gear having internal pockets. The drum covers the housing and is rigidly connected with it and a pipe for supplying gaseous coolant, docked with the drum. The drum is rigidly connected to the body of a coaxially mounted muffle furnace equipped with a perforated insert. The furnace is docked on one side with a material loading chamber having transfer channels and a nozzle. On the opposite side of the furnace is a flue gas exhaust chamber. The chamber for removing process gases is equipped with a channel, a loading device and a pipe.

During the operation of this furnace, it is impossible to separately control the grinding time of the clumping product and the time for further heat treatment of the powder resulting from grinding. The furnace has a rather complicated structure for servicing in case of product sticking to the inner surface of the furnace between the spiral nozzle.

Known rotary kiln for processing clumping product, [RU 2388979 C1, IPC F27B 7/10 (2006.01), publ. 05/10/2010], selected as a prototype, containing an inclined cylindrical body, equipped inside with a perforated drum with grinding elements, a device for loading raw materials and outlet pipes for gaseous and solid products. The cylindrical housing rotates from the drive in bearings. The housing has openings for the exit of products: the upper openings are for gaseous, the lower ones are for solid. A drum in the form of a truncated cone is mounted coaxially inside the housing and rotates from its second drive in its bearings. The drum is filled with balls. The drum has two sections: a section with a solid wall at the smaller base of the cone and a section with a perforated wall adjacent to the larger base. The initial product is loaded into the drum by a screw feeder rotating from a third drive. The drum is mounted on the smaller base of the cone towards the feeder. The case is heated by a heater and equipped with thermal insulation. The bearings are mounted in a bearing assembly, which is screwed to a fixed stand. To be able to adjust the angle of inclination of the furnace and, accordingly, the housing, relative to the horizon, the bearing assembly can be moved vertically with a screw, and the opposite side of the housing, together with the feeder and the third drive, is mounted on a hinge and a stand. The furnace body is installed with an inclination towards the nozzle for the exit of solid products. The half-opening angle of the drum should be greater than the maximum angle of inclination of the body.

This rotary kiln has a complex structure. During operation of the furnace, heating of the supplied mixture of raw materials and ammonium fluoride (hydrodifluoride) requires heating of the cylindrical body, which in turn warms the inner conical drum to the reaction temperature, which requires increased energy costs.

The proposed design of a rotary rotary kiln allows to prevent the mixture from setting with the inner wall of the drum during heating and to heat the raw material directly through the drum wall without spending additional energy.

The rotary rotary kiln, as in the prototype, contains a body insulated from the inside, mounted on racks, a drum filled with balls is placed inside the drum, part of the drum surface is perforated, bearings, a screw feeder connected to the engine, a feed hopper mounted above the screw feeder, heaters, outlet pipes for gaseous and solid reaction products.

According to the invention, the housing is made in the form of a parallelepiped and is rigidly fixed to the frame. Thermal insulation material is placed on the inner surface of the housing; a hollow frame is installed on the thermal insulation material. The drum is cylindrical and mounted on the frame using bearings. Two metal rods are additionally placed in the drum. One end of the drum protrudes from the housing and is inserted into the box, through which a screw feeder is inserted through the hole in the end of the drum. The box on top is equipped with a main pipe for the removal of gaseous products, and from the bottom - a pipe for unloading finely dispersed solid reaction products carried away in countercurrent from the drum. A shaft protruding from the housing is welded to the other end of the drum. The end of the shaft through the gearbox is connected to the motor. A portion of the drum surface on the shaft side is perforated and placed inside the intermediate box, which is connected to the collector of solid reaction products from below and equipped with a pipe for removing gaseous reaction products from above.

The presence of holes in the end of the drum in the feed zone of the feedstock allows the removal of gaseous reaction products by countercurrent. The presence of rods inside the drum, in addition to balls, allows you to "scrape" and further mix the raw materials and fluoride (ammonium hydrodifluoride), preventing the balls from sticking to the inner wall of the drum.

Heating directly the drum itself with the reaction mixture can reduce the cost of metal, and as a result, the cost of heating the furnace.

The proposed design of the furnace requires lower costs for materials, compared with the prototype, and is simpler to manufacture and install.

In FIG. 1 shows a longitudinal section through a rotary kiln.

A rotary rotary kiln contains two pairs of racks 1 and 2, on which a rectangular frame 3 is mounted, equipped with transverse stiffeners. In the upper part of one pair of racks 1, holes 4 are made for placing eyebolts fixing the angle of inclination of the frame 3 relative to the horizon. The casing 5 in the form of a parallelepiped is rigidly fixed to the frame 3. On the inner surface of the casing 5 there is a heat-insulating material 6 on which a hollow frame 7 is provided, equipped with transverse stiffeners. Between the stiffeners of the frame 7 on the insulating material 6 installed tubular electric heaters 8.

A cylindrical drum 11 is mounted on the frame 3 using thrust bearings 9, on the one hand, and a thrust bearing 10, on the other hand. One end of the drum 11 protrudes from the housing 5 and is inserted into the box 12, which is provided with a main pipe 13 for removal of gaseous reaction products, and from the bottom - pipe 14 for unloading a finely divided solid reaction product and ammonium fluoride. A shaft 15 protruding from the housing 5 is welded to the other end of the drum 11. The end of the shaft 15 is connected to the engine 17 through the gear 16. The gear 16 and the motor 17 are mounted on a platform fixed to the end of the frame 3. Thermocouples 18 are inserted inside the frame 7 and are located near the outer the walls of the drum 11.

Grinding bodies are placed inside the drum 11: two metal rods 19 and balls 20. The surface portion of the drum 11, on the shaft 15 side, is perforated 21 and placed inside the intermediate box 22, which is connected to the collector of the solid reaction product 23 from below. equipped with an additional pipe 24 for the removal of gaseous reaction products, and from below a valve (in Fig. 1 shown).

In the protruding from the housing 5, the end face of the drum 11 through the hole 25 and the box 12 is inserted a screw feeder 26 connected to the engine with a control unit 27. Above the screw feeder 26 is installed a hopper 28 for supplying raw materials.

The screw feeder 26, the engine with the control unit 27, the hopper 28 is fixed to one end of the frame 3.

A drum rotary kiln operates as follows. The initial product, which is a mixture of rare-metal raw materials, in particular titanium-containing raw materials (ilmenite concentrate, titanium slag, etc.) and fluoride and / or ammonium hydrofluoride, is loaded from hopper 28 by screw feeder 26 into drum 11. The feed rate of the mixture is varied by adjusting the frequency revolutions using the engine control unit 27. The process of decomposition of raw materials is initiated by heating the drum 11 to 150-250 ° C with tubular electric heaters 8. depending on the required process temperature. The temperature of the outer wall of the drum is determined by thermocouples 18. Thermal insulation material 6 prevents heat dissipation. The loaded material moves along the rotating drum 11, inclined relative to the horizon at a certain angle. The angle of inclination of the frame 3 relative to the horizon is varied by raising its edge from the loading side and then fixing it with eyebolts, which are inserted into the holes 4 of the pairs of struts 1.

The rotation of the drum 11 is provided by the operation of the engine 17 and the gearbox 16, as well as the supporting 9 and thrust bearings 10. When heated, a reaction occurs between the components of the mixture with the formation of a viscous product with high adhesive properties. Then there is the release of water and gas, which leads to the drying of the product and its seizure. Due to the collisions of the rods 18 and the balls 19 with each other and with the inner wall of the drum 11, the product adhering to their surfaces is removed and crushed to a size that allows them to pass through the perforation 21. When passing through the perforation 21, the solid reaction product enters the box 22, from where it unloaded into a removable collector 23. In the process of changing the collector 23, it is possible to block the duct 22 with a valve. The gaseous reaction products formed in the process are discharged countercurrently through the opening in the drum 25 to the box 12. This captures part of the finely dispersed solid reaction product and ammonium fluoride or bifluoride, most of which settles in the box 12. When filling the box 12, the accumulated finely divided solid is unloaded the reaction product through the pipe 14. The gaseous product obtained during the reaction is sent through the pipe 13 to the gas purification system. The beginning of the removal of gaseous reaction products through the pipe 24 indicates the need to increase the vacuum in the drum 11 through the hole 25.

The length of time the mixture stays in the drum 11 of the furnace depends on the angle of inclination of the furnace relative to the horizon, and the angle of inclination of the drum 11 is adjusted by changing the location of the beginning of the frame 3 relative to the beginning of the struts 1 supporting it.

The rotational speed of the drum 11 affects the mode of grinding the mixture. The most effective for grinding this type of material is the waterfall mode, when the ball 20 at the upper point of rise breaks away from the wall and returns to the lower point along a parabolic path with impact. However, the rotation speeds corresponding to this regime are close to critical when the balls 20 begin to rotate together with the drum 11 without crushing the material. Together with the balls 20, two metal rods 19 are placed in the chemical reaction zone, the trajectories of which do not allow the balls 20 covered with a viscous adhesive layer by the reaction product to grasp the inner wall of the drum 11.

After grinding the reaction product to a size that allows it to pass through the perforation 21, the reaction product through the box 22 is discharged into a removable collector 23. The product is a fluoroammonium compound, further processing of which allows oxides and other compounds to be obtained.

Claims (1)

A rotary rotary kiln containing an inside insulated casing mounted on racks, inside of which there is a drum filled with balls, a part of the drum surface being perforated, bearings, a screw feeder connected to the engine, a feed hopper installed above the screw feeder, heaters, outlet pipes for gaseous and solid reaction products, characterized in that the casing is made in the form of a parallelepiped and is rigidly fixed to the frame, the insulating material is placed on and on the inner surface of the housing, a hollow frame is installed on the heat-insulating material, the drum is made cylindrical and mounted on the frame using bearings, two metal rods are additionally placed in the drum, while one end of the drum protrudes from the housing and is inserted into the box through which there is an opening in the end a screw feeder is inserted in the drum, the box on top is equipped with a main pipe for discharging gaseous products, and from the bottom - a pipe for unloading finely divided solid reaction products carried away by the countercurrent from the drum, and a shaft protruding from the housing is welded to the other end of the drum, the shaft end through the gearbox is connected to the aforementioned motor, the drum surface portion from the shaft side is perforated and placed inside the intermediate box, which is connected to the collector of solid reaction products from below and from above equipped with a pipe for the removal of gaseous reaction products.

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