RU2413148C1 - Reverberatory furnace for aluminium scrap re-melting - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: furnace consists of case made with refractory external side, front and back end walls, of storage bath and of inclined platform restricted with sole and walls, of roof, of tap hole, of gas duct and of welded frame whereon everything is arranged. Walls of the furnace are externally heat insulated with four layers of sheet asbestos cardboard. The inclined platform and the storage bath are laid out of sole blocks MLS-62 on two layers of asbestos cardboard and on a pad out of dry high-silica sand which facilitates maintaining heat in the furnace bath preventing its emittance to the frame. Inside the frame of the furnace is lined with three rows of light-weight-bricks and two rows of sheet asbestos cardboard reducing heat emission from the bath via the frame. On top the roof of the furnace has a layer with triple heat-insulating coating, a layer of light-weight bricks and a layer of refractory heat insulating mats on it to additionally save heat in the furnace. In the side wall of the furnace there are arranged three burners; also, two-row eight-mixing and GBG-1.2 burners are directed to the inclined platform, while one burner GBG-1.2 is directed to the sole of the furnace. The furnace consists of the tap hole in the side wall made out of quick removable tap bricks in a box, of lined rotating pan with a lined chute welded to it and rotating at angle of 130° for casting metal into casting equipment positioned in a sector at angle of 130° and of a drive for lifting and lowering a door of a charging hole. The drive consists of an electric engine, of a clutch, of a worm reducer, of two shafts with pulleys, of counter-weights, of cables, of chains and of the door.

EFFECT: simplified design, low losses of heat and ecologically safe scrap re-melting.

7 cl, 3 dwg

Description

The invention relates to ferrous metallurgy, and in particular to smelting units for remelting secondary aluminum scrap and waste aluminum alloys into ingots and ingots. The furnace can be used for refining, producing alloys, averaging the chemical composition.

A known analogue is a reflective furnace for remelting metal (RF patent information No. 2155304), which contains, as in the claimed furnace, a housing formed by side, front and rear end walls, a storage bath limited by a hearth and walls, an inclined platform, a vault, a drain drain flue.

The disadvantages of this furnace are:

1. The complexity of the design due to the presence of two arches (small above the inclined platform and large above the storage bath).

2. The lack of external thermal insulation of the furnace, reducing heat loss to the external environment.

3. Lack of dust and gas cleaning.

4. From the description of the furnace it follows that the furnace is equipped with only one nozzle, which is clearly not enough to ensure a high rate of penetration of the charge and maintaining a forced melting mode. Due to the above disadvantages, the furnace cannot provide a solution to the technical problem.

A known analogue is a reflective furnace for remelting metal (information source RF patent No. 2047663), containing, as in the claimed furnace, a housing formed by side, front and rear end walls, a storage bath and an inclined platform, a vault, a drainage gap limited by a hearth and walls flue.

The disadvantages of this furnace are:

1. The high cost and complexity of the accumulating heat pillows (lightweight refractory bricks, blooms).

2. The large depth of the liquid metal in the bath makes the mixing process difficult, as a result of which the liquid metal will not be homogeneous.

3. The lack of external thermal insulation of the furnace, reducing heat loss to the external environment.

4. Lack of dust and gas cleaning.

5. From the description of the furnace it follows that the storage bath is made of fireclay bricks of grade SB, which has low refractoriness and a low temperature of the onset of softening, which leads to frequent repairs of the furnace. Due to the above disadvantages, the furnace cannot provide a solution to the technical problem.

A known analogue is a reflective furnace for remelting metal (information source RF patent No. 2361162), which is the closest (prototype), containing, as in the claimed furnace, a housing formed by refractory outer side, front and rear end walls, limited by the hearth and the walls of the storage bathtub and incline platform, arch, drain tap hole, gas duct.

The disadvantages of this furnace are:

1. The great complexity of the manufacturing process of external wall insulation.

2. Raising and lowering the slag and working window dampers is done manually.

3. The furnace uses stationary chutes for casting the weld metal.

4. Lack of dust and gas cleaning.

Due to the above disadvantages, the furnace cannot provide a solution to the technical problem.

The objective of the invention is the creation of a gas bath of a reflective type furnace for remelting aluminum scrap of a simple design, which allows the process of remelting on natural and artificial traction with a dust and gas cleaning system, to reduce the loss of metal and heat to the environment, and also to increase its life and productivity.

EFFECT: developed furnace is simple in design, having high productivity, low metal waste, long service life, which allows: to use scrap unsorted from foreign inclusions, to reduce heat loss to the environment due to special thermal insulation, to conduct the remelting process on natural and artificial traction with a dust and gas cleaning system, which makes it environmentally friendly.

The specified technical result is achieved due to the fact that a culvert, a drain drain and a flue are introduced into the reflective furnace for remelting aluminum scrap, containing a casing formed by refractory outer side, front and rear end walls, an accumulation bath and an inclined platform bounded by a hearth and walls. welded frame, which has a lining of three rows of lightweight bricks and two layers of sheet asbestos board, laid out in the frame under the bottom of the storage bath and an inclined platform. Three rows of lightweight bricks and two layers of sheet asphalt board can reduce heat loss from the bathtub and the inclined platform through the frame to the floor.

In addition, the storage bath and the inclined platform are made of MLS-62 hearth blocks laid on two layers of asbestos board and have a pad of dry quartz sand. Hearth blocks have high refractoriness and resistance (service life according to practical data is up to 6.5-7.5 years). Two layers of asbestos board and dry quartz sand allow you to further maintain the temperature of the metal in the furnace bath and the inclined platform.

At the same time, the furnace has a notch in the side wall for the release of molten metal, a lined rotary bowl with a lined chute welded to it, which can be rotated through an angle of 130 °, providing casting of metal in casting equipment located in a sector with an angle of 130 °. The tap hole is made in quick-change flying brick in a box to ensure the possibility of their replacement without stopping the furnace.

At the same time, a steel box is welded to the furnace frame, which has thermal insulation between it and each wall, consisting of four layers of sheet asphalt board. Four layers of sheet asphalt board allow you to further maintain the temperature of the walls of the furnace.

It is important to note that the arch of the proposed furnace has a layer with a triple heat-insulating coating on top, a layer of lightweight brick and a layer of refractory heat-insulating mats on it to further retain heat in the furnace.

In addition, in order to maintain the temperature in the furnace bath, to warm the recess, and if necessary, to overheat the alloy, as well as to increase productivity and maintain a forced melting mode, the following were installed in the side wall: two burners (two-row injection eight-mixing and GBG-1.2) are directed to an inclined platform and one burner GBG-1,2 is directed to the bottom of the furnace. The furnace can work with the power off due to the use of an injection double-row eight-mixing burner.

Moreover, the design of the proposed furnace introduced a drive for raising and lowering the shutter of the loading (working) window, consisting of: an electric motor, a coupling, a worm gear, two shafts with pulleys, counterweights, cables, chains and a shutter.

It should be noted that the installation of a dust and gas treatment was introduced into the composition of the proposed furnace, which allows the melting process to be carried out on natural and artificial draft with the cleaning of flue gases from harmful substances and dust.

Introduction to the proposed furnace of the above provides a solution to the problem.

Figure 1 is a longitudinal section of a furnace.

Figure 2 is a transverse section of the furnace (view of the chimney).

Figure 3 is a plan view of the furnace.

The furnace contains a housing formed by refractory outer side 1, front 2 and rear 3 end walls, an accumulation bath 4 and an inclined platform 5. The walls are laid out in three bricks made of direct fireclay bricks ША 1 No. 5 and one and a half ША 1 No. 12 GOST 8691-73 ( figure 1). The body is mounted on a welded frame 6, which is welded from I-beam No. 22. Under the furnace 7 and the inclined platform 5 are laid out from the bottom blocks MLS-62 (GOST 24704-81) (thickness 300 mm, width 400 mm, length 1000 mm or 500 mm). The threshold of the loading window of the furnace is also laid out from the bottom blocks MLS-62 (thickness 300 mm, width 400 mm, length 1000 mm). Hearth blocks МЛС-62 contain more alumina, have greater refractoriness and a higher softening temperature than the hearth blocks of the MKRS-50 prototype. Under the furnace 7 consists of three rows of hearth blocks of six pieces in each row, laid on a welded frame 6 and a sand pad, from the bottom of which the sideboard 8 is laid in two layers. Inclined platform 5 consists of three rows of hearth blocks, four in each row and one row of hearth blocks with a saw for the best cleaning of a part of the hearth and inclined platform, laid on a row of lightweight brick 9, placed on an edge, which is located on a sand block, below which laid asbokarton 8 in two layers. Hearth blocks have high refractoriness and resistance (service life according to practical data is up to 6.5-7.5 years). Two layers of asbestos board 8 and dry quartz sand allow you to further maintain the temperature of the metal in the bathtub of the furnace and the inclined platform.

The welded frame 6 inside has a lining of three rows of lightweight brick 10 and two layers of sheet asbestos board 11. Three rows of lightweight brick 10 and two layers of sheet asbestos board 11 can reduce heat loss from the bathtub and the inclined platform through the welded frame 6 to the floor.

As a binder, a refractory solution is used, consisting of refractory clay (20%), fireclay powder (75%), water glass (3%) and phosphon (aluminochromophosphate mixture, 2%).

The thickness of the seams is 1-2 mm.

The furnace has a notch 12 in the side wall 1 for the release of molten metal, a lined rotary bowl 13 with a lined chute 14 welded to it, which can be rotated by an angle of 130 °, providing casting of metal in casting equipment located in a sector with an angle of 130 ° ( figure 3 shows a carousel, and, in principle, in a sector with an angle of 130 ° can be installed, for example, a casting conveyor and large molds, etc.). Letka 12 is made in quick-change flying brick 15 in the box to ensure that they can be replaced without stopping the furnace. In the event of wear of a quick-change summer brick (cracks, a significant increase in the diameter of a notch, potholes, slagging, etc.), it can be replaced without stopping the furnace for repair and without destroying the walls and arch. A notch 12 for the release of molten metal is located in the side wall of the furnace.

A steel box 16 is welded to the welded frame 6 of the furnace, having heat insulation between it and each wall, consisting of four layers of sheet asbestos-board 17. Four layers of sheet asbestos-board 17 can further maintain the temperature of the walls of the furnace. The fastening of the steel box 16 to the welded frame 6 is carried out by vertical channels No. 14 (18) (Fig. 2). To prevent the expansion of the masonry furnace vertical channels have a bunch of horizontal channels No. 14 (19) (figure 3).

In the front end wall 2 of the housing, a loading window 20 is made. The loading window 20 has a vault 21 laid out according to the pattern from a chamotte end wedge ША 1 No. 22, 23 (Fig. 1). A slag window is laid out in the side wall, closed by a lined rotary damper 22 (Fig. 3, designed to clean most of the hearth and tap hole from slag). In the rear end wall 3, a gas duct 23 is laid out, having an arched arch 24, supported by heel bricks 25, in addition, there is an explosive valve 26.

To maintain the temperature in the bathtub 4 of the furnace, to heat up the notch 12 and, if necessary, to overheat the alloy, as well as increase productivity and maintain forced melting mode, two burners are installed in the side wall 1: two-row injection eight-mixing (27) and GBG-1,2 (28 ) to an inclined platform, and one burner GBG-1,2 (29) is directed to under 7 furnaces. The furnace can work with the power off due to the use of an injection double-row eight-mixing burner. Each burner has its own gas control valve and its own burner tunnel for stable flame burning.

The arch of the proposed furnace has a layer with a triple heat-insulating coating 30, a layer of lightweight brick 31 and a layer of refractory heat-insulating mats 32 on it for additional heat storage in the furnace.

Arch 33 of the furnace is made according to the template from the wedge of the butt ША 1 No. 22, 23 GOST 8691-73 and is based on the heel bricks 34 ША 1 No. 67 GOST 8691-73.

Moreover, the design of the proposed furnace introduced a drive for raising and lowering the shutter of the loading (working) window, consisting of an electric motor 35, a coupling 36, a worm gear 37, two shafts 38 with pulleys 39, counterweights 40, cables 41, chains 42 and shutters 43 Two shafts 38 have pressed pulleys 39 at their ends, which rotate along with the shafts in the rolling bearings located in posts 44. Four posts 44 are welded to the metal structure of the furnace. The four pulleys 39 have grooves in the shape of chains, due to which the chains thrown over the pulleys have a large contact area, during the operation of the drive, slippage of the chains is excluded. The weight of the loading window shutter 43 is balanced by the weight of the two counterweights 40. One cable 41 is connected to the counterweight 40, and the other is wound through the pulley 45 onto the drum 46 for raising and lowering the loading window shutter. The welded furnace damper 43 has thermal insulation consisting of three layers of asbestos board 47 and a lightweight brick lining 48. In the lower position, the damper 43 rests on the window sill 49. Two handles 50 are welded to the damper.

It is significant to note that the heel beams 51 are welded from channels No. 30.

The furnace is mounted on a concrete foundation 52 having a welded frame 53. The charge is loaded into the furnace using a vibro-loading unit 54, into which the charge is loaded by a crane. The smelted metal is poured from the furnace through the chute 14 into the molds 55, placed on the carousel 56. The flue gases generated during the combustion of fuel enter the borovok 57, on which an explosive valve 58 and a gate 59 are installed to adjust the amount of vacuum in the furnace (during natural draft) .

It should be noted that the installation of a dust and gas treatment unit 60 was introduced into the proposed furnace, which allows the remelting process to be carried out on natural and artificial draft with the cleaning of flue gases from harmful substances and dust (the dust and gas treatment installation is shown only in Fig. 3). In order to reduce the temperature of the flue gases to 160-200 ° C, a mixing chamber 62 is installed in front of the exhaust fan 61. Two gates are installed in the mixing chamber: the gate 63 controls the artificial draft, and the gate 64 controls the fresh air supply of the workshop to dilute the flue gases. All gates are serviced from the service site 65. By means of a smoke exhaust pump 61, flue gases are pumped to a dust and gas treatment unit 60, where an adsorbent layer and bag filters pass and, then, a blower 66 is passed through a duct 67 to a chimney (not shown).

The natural draft furnace operates as follows. The mixture is loaded with a crane into a vibro-loading installation 54. A door 12 is plugged, molds 55 are heated on the carousel 56 and they are painted with non-stick paint. The furnace is calcined in accordance with the technological instructions, in the calcined furnace on an inclined platform 5 through the loading window 20 with the aid of a vibro-loading installation 54, un-finished aluminum scrap is loaded with ambient temperature. The flame of three gas burners 27, 28, 29, walled up in special openings of the side wall 1, heats the scrap to the melting temperature. The metal melts and flows down the inclined platform 5 into the bath of the furnace 4. The burners are installed obliquely, so the flame of the burners is inclined at an angle to the inclined platform 5, the bath, and it glides along the charge lying on the inclined platform and the bath with molten metal, smoothly bends around the side wall 1, then, twisting, rises to the arch 33, flows part of it in the opposite direction, passes a second time along the surface of the molten metal, providing its secondary heating, and then the flue gases enter the chimney 23 and, then, through the bore 57 are removed into the fluepipe (not shown). It is important to note that, before the furnace is operating, the metal and alloy smelter rises to the service area 65 and opens the gate 59 on the borovka 57, and closes the gate 63 on the mixing chamber. In the process, heat is accumulated in vault 33, from where it is reflected on the metal. A layer with a triple heat-insulating coating 30, a layer of lightweight brick 31, a layer of heat-insulating mats 32, thermal insulation 17 of the walls, bottom 7, inclined platform 5 and heat-insulating layers of the furnace frame provide high thermal insulation of the furnace. In the smelting process include, if necessary, one, two, three burners. All burners are turned on to achieve high furnace performance, i.e. ensure forced melting mode. During the melting process, the charge is loaded several times, the scrap melts, the moisture in it evaporates, decomposing into oxygen and hydrogen, and all inclusions remain on inclined platform 5, the melting temperature of which is higher than that of the aluminum alloy. These wastes (alterations: cast iron and steel rings, liners, bushings, studs, pushers, valves, etc.) do not fall into the molten metal, since they are periodically removed with a scraper from the surface of the inclined platform 5 to the slag. After the molten scrap loaded into the furnace is completely melted, the liquid metal is flux-treated, the metal is thoroughly mixed in the bath and the spectral analysis laboratory confirms the grade of the obtained alloy, letka 12 is opened and the alloy is cast into molds 55 of carousel 56.

After the casting of the metal, a tap hole 12 is plugged, and the process is repeated.

An artificial draft furnace operates as follows.

Before the furnace starts, the metal and alloys smelter rises to the service area 65, closes the gate 59 on the borovka 57, and opens the gates 63 and 64 on the mixing chamber 62. Next, dust with spent adsorbent is removed from the dust and gas treatment unit 60. Fresh adsorbent (activated carbon 12 kg and fluff lime in the amount of 40 kg) is loaded onto the rotary grate with a large number of holes.

The installation of dust and gas cleaning is included. The operations carried out on the furnace are the same as during the operation of the furnace on natural traction. The flue gases released during the melting of the metal in the furnace pass through mixing chamber 62, are diluted with fresh air from the workshop, and their temperature drops from 950-1050 ° C to 160-200 ° C. Next, the smoke exhauster 61 flue gases are pumped into the installation of dust and gas cleaning, where they are cleaned from harmful substances and dust. When flue gases pass through the adsorbent layer, a "fluidized bed" is formed, in which flue gases are intensively cleaned of harmful substances. In the upper part of the dust and gas cleaning installation, flue gases are cleaned from dust in eight bag filters. Then the cleaned flue gas blower 66 is fed through the duct 67 into a chimney (not shown). After casting the liquid metal, the bottom of the slag is cleaned, the notch 12 is plugged, and the cycle repeats.

The furnace is distinguished by its simplicity of design, low heat loss and can operate on natural and artificial traction with a dust and gas cleaning system, which makes the process of remelting aluminum scrap environmentally friendly.

Claims (7)

1. Reflective furnace for remelting aluminum scrap, comprising a housing formed by refractory outer side, front and rear end walls, an accumulation bathtub and an inclined platform defined by a hearth and walls, a roof, a drain drain and a gas duct, characterized in that the furnace body is placed on a welded the frame, which has a lining of three rows of lightweight brick and two layers of sheet asbestos board, laid out in the frame under the bottom of the storage bath and inclined platform, while the storage bath and inclined platform They are made of hearth blocks of the MLS-62 brand, laid on two layers of asbestos-cardboard, and are lined with dry quartz sand. 2. The furnace according to claim 1, characterized in that it is equipped with a dust and gas cleaning installation to enable remelting on natural and artificial draft with the cleaning of flue gases from harmful substances and dust. 3. The furnace according to claim 1, characterized in that it has a notch in the side wall for the release of molten metal, made in a quick change brick in the duct, lined with a rotary bowl with a lined chute welded to it, made with the possibility of rotation through an angle of 130 ° for casting metal into casting equipment located in a sector with an angle of 130 °. 4. The furnace according to claim 1, characterized in that a steel box is welded to the furnace frame, having heat insulation between it and each wall, consisting of four layers of sheet asbestos board. 5. The furnace according to claim 1, characterized in that the arch has a layer with a triple heat-insulating coating on top, a layer of lightweight brick and a layer of refractory heat-insulating mats on it. 6. The furnace according to claim 1, characterized in that an injection two-row eight-mixing burner and a block gas burner GBG-1,2 directed to an inclined platform and a block gas burner GBG-1,2 directed to the bottom of the furnace are installed in the side wall. 7. The furnace according to claim 1, characterized in that it is equipped with a drive for raising and lowering the shutter of the loading window, comprising an electric motor, a coupling, a worm gear, two shafts with pulleys, counterweights, cables, chains and a shutter.

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