Drum furnaces. For melting various metals Drum zinc melting furnaces
Zinc is a heavy, fusible metal; Tmelt = 420 °C, p = 7.13 kg/dm3. The low boiling point of zinc (*boil = 907 °C) limits the permissible temperature of the metal when melting all the alloys in which it is included. The enthalpy of zinc at 500 °C (about 300 kJ/kg) is three times lower than the enthalpy of molten aluminum. The electrical resistivity of zinc melt is 0.35-10~6 Ohm.
At low temperatures in air, zinc oxidizes, forming a dense protective film of Zn03* 3Zn(OH)2. However, in smelting furnaces, zinc is oxidized by the following reactions:
2Zn + 02 = 2ZnO, Zn + H20 = ZnO + H2, Zn + C02 = ZnO + CO.
To protect against oxidation, smelting can be carried out in a protective or neutral atmosphere, for example in a nitrogen environment. However, in practice, in most cases it is sufficient to prevent the metal from overheating above a temperature of 480 °C, at which intense oxidation and saturation of zinc with gases begins. At this temperature, zinc and its alloys do not have a noticeable effect on the refractory lining of the furnace and the cast iron or steel crucible. An increase in temperature leads to the dissolution of the iron of the crucible in the molten zinc.
Furnaces for melting zinc alloys
Given the low melting and boiling point of zinc, zinc alloys are usually smelted in crucible furnaces, heated by burning fuel or using electrical resistance and induction. Zinc alloys should not be melted in arc furnaces, since the inevitable local overheating of the metal near the combustion of the arc leads to intense evaporation and oxidation of zinc. Channel induction furnaces are used for melting zinc alloys. At KamAZ, the TsAM10-5 alloy for injection molding was smelted in three induction channel furnaces with a capacity of 2 tons each with a neutral lining. However, overheating of the metal in the channel leads to instability of the electrical melting mode (the so-called zinc pulsation) and forces the power transferred to the furnace to be limited.
Melting technology
The main part of the charge usually consists of zinc foundry alloys in pigs, return and scrap of zinc alloys. A mixture of calcium, potassium and sodium chlorides, ammonium chloride or cryolite are used as coating fluxes. For blending, primary aluminum in pigs, cathode copper and metallic magnesium are used. All components of the charge must be cleaned of oils, moisture and other impurities. Melting is carried out without allowing the bath to overheat above 480 °C. Based on the results of the express analysis, the chemical composition is adjusted.
A steel bell is used to introduce magnesium. Once the desired chemical composition is obtained, the metal is overheated to 440...450°C and poured into a ladle heated to the same temperature. In a ladle under an exhaust hood, the melt is refined using tablets of the complex degasser “Degaser”, which contain 87% hexachloroethane, 12.7% NaCl, 0.3% ultramarine. Refining can also be carried out by settling, purging with inert gases and filtration.
Theoretical essence of the process
The essence of furnace smelting is the processing of a mixture of rich sulfide lead concentrate with solid fuel using a jet of compressed air. In this case, partial roasting of PbS occurs with the formation of PbO and PbSO 4 and the interaction reaction between PbS and the products of its oxidation - PbO and PbSO 4. Roasting and reaction smelting are carried out simultaneously; In addition, part of the lead is reduced by fuel carbon.
The firing reaction of PbS and its thermal effect is as follows:
2PbS + ZO 2 = 2PbO + 2SO 2 + 201,360 cal (8450 kJ), (1)
the above reaction is summary, since the oxidation of lead sulfide occurs in several steps;
2PbO + 2SO 2 + O 2 = 2PbSO 4 + 183,400 cal (7680 kJ).(2)
Noticeable amounts of lead sulfate are formed during the oxidation of sulfide already at 200-300°C; the process proceeds extremely slowly.
After partial firing, the charge contains the following chemical lead compounds in the solid state: PbS, PbO and PbSO 4 . When these substances, taken in a certain ratio, are heated, the following reactions occur:
PbS + 2Pb0 = 33b + SO 2 - 52,540 cal (2200 kJ), (3)
PbS + PbSO 4 = 2Pb + 2SO 2 - 97,380 cal (4070 kJ). (4)
At a certain temperature and pressure of SO 2, chemical equilibrium occurs: reactions proceed at the same speed in both directions. As the temperature increases, the equilibrium is disturbed, and reactions proceed from left to right towards the formation of Pb and SO 2. Thus, increasing the temperature is beneficial for reaction smelting, since it increases the yield of metallic lead and accelerates the roasting of PbS. But both for firing (to avoid clumping) and for the reaction smelting itself, the charge must be kept in a solid state. Therefore, the reaction smelting process is carried out at temperatures no higher than 800-850°C. At higher temperatures, PbO melts, delamination by density occurs, which disrupts the contact between lead sulfide and lead oxide and the melting of lead stops.
Excess lead oxide is reduced by C and CO according to the reactions:
PbO + C = Pb + CO; (5)
PbO + CO = Pb + CO 2. (6)
To carry out these reactions, a certain amount of carbonaceous fuel is introduced into the furnace charge. Usually this is coke breeze in an amount of 4-10% of the weight of the charge. The more intense the process and the more sulfide sulfur in the charge, the less fuel is required for furnace smelting.
The optimal coke size is from 5 to 15 mm. Larger coke particles contribute to the segregation of the charge, and smaller ones are carried away with dust.
The short-drum furnace is a steel riveted casing lined with high-alumina brick of the composition,%: 65-70 A1 2 O 3; 20-25 SiO 2; 3TiO2; 5Fe 2 O 3 ; 0.5CaO. Between the furnace casing and the refractory lining there is a compacted layer of plastic clay 50 mm thick in case the lining expands when it is heated.
Melting is carried out intermittently, each operation lasts about 4 hours. Having loaded several tons of charge, the short-drum furnace is rotated at a speed of 0.5-1.0 rpm and vigorously heated with burned coal dust to the temperature of intensive reaction (1100°C). The oven can rotate in two opposite directions. Rotation ensures good contact between lead sulfides and lead oxides, which is necessary for successful reaction smelting. Flue gases pass through the waste heat boiler and are filtered in bag filters.
By the end of the smelting, its products (lead, speis, matte, slag) are well separated by density in a furnace with a deep bath and are released separately.
The invention relates to non-ferrous metallurgy, namely to melting units for processing (remelting) non-ferrous metal waste, in particular for remelting secondary aluminum scrap and waste aluminum alloys into ingots and pigs. The furnace can be used for refining, producing alloys, and averaging the chemical composition of scrap.
A device for a rotating metallurgical melting furnace for remelting metal is known (RF patent No. 2009423 C1), which is an analogue of the invention.
Just like the proposed invention, the analogue contains a cylindrical body, a loading hole, a burner, a tap hole for releasing molten metal and a tap hole for draining slag.
1. The complexity of loading, which is caused by the need to use a special casting crane, and the complexity of the process of pouring metal from the furnace to the casting machine, which requires an intermediate pouring ladle.
2. Lack of a dust and gas purification system that would reduce the harmful effects of smelting in a furnace on the external environment.
A device for a rotating metallurgical melting furnace for processing waste non-ferrous metals is also known (RF patent No. 2058623), which is an analogue of the invention.
The furnace described in the patent contains, like the proposed one, a cylindrical body, a burner device, a loading hole, and a tap hole for draining the molten metal.
The disadvantages of this oven are:
1. The location of the tap hole for releasing the molten metal and the tap hole for draining slag from the end of the furnace complicates the process of feeding metal to the casting machine, since this requires the presence of an intermediate pouring ladle.
2. The location of the loading hole on the cylindrical part of the furnace complicates its design, since it is necessary to provide a special sealing device in the lid of the loading hole, because the furnace rotates.
3. Lack of a dust and gas purification system that would reduce the harmful impact on the environment during smelting.
4. There is no thermal insulation that would reduce heat loss to the environment.
Due to the presence of the above-mentioned shortcomings, the furnace cannot solve the technical problem.
The closest analogue (prototype) in relation to the claimed melting furnace is a rotating melting furnace for processing non-ferrous metal waste (RF patent No. 2171437), which, like the claimed furnace, contains a cylindrical body, a burner device, a loading hole, and a tap hole for draining the molten metal. The prototype of the inventive furnace has the following disadvantages:
1. The stove does not have a quick-change lightweight brick, which allows for quick repairs in case of wear.
2. Lack of a dust and gas purification system that would reduce the harmful impact on the environment.
3. There is no thermal insulation that would reduce heat loss to the environment.
Due to the presence of the above-mentioned shortcomings, the furnace cannot solve the technical problem.
The objective of the invention is to create a rotating drum melting furnace of simple design for processing (remelting) non-ferrous metal waste, in particular, for processing aluminum scrap, which allows reducing emissions of harmful gases into the atmosphere, reducing heat loss to the environment, and also increasing its service life. More precisely, the creation of a rotating drum melting furnace, which during the melting process rotates relative to the horizontal axis in both directions at an angle of 105° using an electric drive.
Technical result - the developed furnace is simple in design, has a long service life, allowing: the use of aluminum shavings, aluminum scrap, reducing heat loss to the environment due to thermal insulation of the furnace casing and end walls, conducting the remelting process on artificial and natural draft with a dust and gas purification system , which makes it environmentally friendly; in addition, during the melting process, it performs rotational movements relative to the horizontal axis in both directions at an angle of 105° using an electric drive.
The specified technical result is achieved due to the fact that a heat-insulating layer consisting of three sheets is introduced into a rotating drum melting furnace for processing waste non-ferrous metals, containing a cylindrical body, a burner device, a loading hole (window), and a tap hole for draining the molten metal according to the present invention. flexible heat-insulating glass fiber mullite-siliceous cardboard and a layer of lightweight fireclay, onto which a layer of lining made of mullite non-shrink ramming mass is pressed; a gas four-mix injection rectangular burner is used as a burner device, in which two mixers with a perforated hemisphere are placed in the bottom row, producing a flame 0.7 long meters, and on the top row there are two mixers with twelve fins at the end of the mixer on the inside, which, when burning the gas-air mixture, have a flame 2.5 meters long, while a mechanism for rotating the burner shield is introduced, in addition, the furnace is designed to operate on natural and artificial draft with a dust and gas purification system to achieve an environmentally friendly process, which includes: a mixing chamber, a smoke exhauster, a dust and gas purification unit and a cartridge filter; moreover, during the melting process, the furnace, using a drive mechanism, rotates relative to the horizontal axis in both directions at an angle of 105° .
The introduced thermal insulation layer, consisting of three sheets of flexible thermal insulating glass fiber mullite-silica cardboard and a layer of lightweight fireclay, allows to reduce heat loss to the environment, and also allows you to additionally maintain the temperature of the metal in a drum swing melting furnace for processing non-ferrous metal waste (hereinafter referred to as a furnace). The service life of the furnace is increased due to the use of mullite-corundum ramming mass, which has high fire resistance and durability.
Moreover, the proposed gas four-mix rectangular injection burner contains a flame-stabilizing tunnel, a refractory ramming mass, four mixers united by a common welded gas distribution chamber, in each mixer four nozzles are drilled at an angle of 26 degrees to their axes, with the lower mixers being in the upper part a pipe with a diameter of 62×10 mm and a length of 300 mm, contains in the lower part a device for final mixing of the gas-air mixture, consisting of a divider made in the form of a cone, a disk, a sleeve and a perforated hemisphere, and the upper mixers are a pipe with a diameter of 90×10 mm, in this case, the mixers, parts for the mixers and the cast flame-stabilizing tunnel, put on the gas distribution chamber connecting the mixers and on the burner casing, are made of heat-resistant cast iron ChYUKhSh. The flame-stabilizing tunnel has an inclined partition, which makes it possible to receive from the lower mixers with a perforated hemisphere a flame that melts the charge located closer to the burner, and from the two upper mixers a flame that melts the charge located in the middle of the furnace and closer to the end wall farthest from the burner. Heat-resistant cast iron, used as a material for the manufacture of mixers, parts for mixers and a cast flame-stabilizing tunnel, allows you to increase the service life of the burner and, naturally, the stove. The rated thermal power of the proposed burner is 1.0 MW.
At the same time, a mechanism for rotating the burner shield was introduced into the furnace design, consisting of: a column, inside of which a shaft is placed, with the ability to rotate at an angle of 100° from the hydraulic cylinder, while a bracket with a pipe welded to it is rigidly fixed to the shaft, through which it is supplied from the gas pipeline gas into a gas four-mix injection burner; in addition, a burner shield with a burner is welded at the end of the bracket. The burner shield rotation mechanism introduced into the furnace design allows for improved working conditions for the furnace operating personnel. A very important fact is that the mechanism for rotating the burner shield allows you to quickly replace a worn-out burner without disassembling the furnace; in addition, through the window into which the burner is inserted, alloying, refining of the liquid alloy, and also processing with fluxes can be carried out. In addition, to increase the productivity of the furnace and increase the volume of metal output, the charge can be loaded into the furnace through the burner window (with the burner retracted) using a vibrating loading machine.
At the same time, a rotating drum melting furnace for processing non-ferrous metal waste is designed to operate on natural and artificial draft with a dust and gas purification system, and in the dust and gas purification unit, harmful substances contained in flue gases are removed, as well as from coarse and medium dust, in a cartridge filter from fine dust. The cartridge filter has the following technical characteristics; productivity for purified gas 11000 m 3 /hour; number of filter elements 11 pieces; number of purge valves 6 pieces; thermal insulation thickness 30 mm; degree of purification - 96%; dimensions 2800×2000×3400 mm. Work on natural draft is carried out in case of repair of individual units of the dust and gas purification system.
Introduction to the design of the furnace of the above devices, materials, etc. provides a solution to the problem.
It should be noted that it is necessary to load scrap (for example, aluminum) into a furnace for melting, crushed in a grinder (shredder) and undergoing magnetic separation (to separate cast iron and steel in the form of bushings, liners, pushers, pins, pins, etc., which are located in motor scrap). The design part of the application for an invention shows:
Fig.1 is a side view of the furnace and from the burner side;
figure 2 - furnace lining;
figure 3 - gas injection burner;
Fig.4 is a section A-A of a gas injection burner;
figure 5 - dust and gas purification unit;
Fig.6 - cartridge filter;
Fig. 7 is a plan view of the furnace with casting and dust and gas cleaning equipment.
The proposed rotating drum melting furnace, then a furnace, for processing non-ferrous metal waste, mainly aluminum scrap, consists of a cylindrical casing 1 welded from a steel sheet 8 mm thick. The end walls 2 of the casing 1 are detachable and are secured with twenty-four bolts 3, twenty-four nuts 4 and twenty-four spring washers 5 of Fig.1. In the cylindrical part of the casing 1 there is a loading window 6, through which the charge is loaded by the vibration loading machine 7 of Fig. 1, 7. The molten metal is released through a tap hole 8 located in the lower end wall 2 of the furnace. Taphole 8 is made of quick-change taphole brick (not shown), which allows for quick repairs in case of wear. The repair is carried out within 15-20 minutes, and the furnace lining is not disassembled.
Two cast support rings 9 are attached to the furnace casing 1. Each support ring 9 has a smooth support surface. The furnace casing 1 in a horizontal position rests freely on four guide rollers 10. The guide rollers 10 have an axis 11 and are fixed in four cast brackets 12, which are mounted on supports 13 of cast brackets 12 attached to the frame 14 of the furnace. On one axis 11 next to the guide roller 10 there is a gear 15 fixed, which meshes with the drive gear 16. The furnace frame 14 has steel supports 17 at the bottom, on which the furnace stands on the concrete floor 18 of the foundry. The steel supports 17 are secured to the concrete floor by 18 foundation bolts (not shown). The melting furnace drive is electric and includes: drive gear 16, coupling 19, worm gear 20 and electric motor 21. When loading the melting furnace with charge, the working window 6 is on the side, during melting it is at the top. During the melting process, the furnace, using an electric drive, rotates relative to the horizontal axis in both directions at an angle of 105°. At the same time, heat transfer from the lining to the metal is improved, in addition, the processes of modification, flux treatment and mixing of the metal in the furnace are accelerated. In addition, to increase the productivity of the furnace and increase the volume of metal output, the charge can be loaded into the furnace through the burner window (with the burner retracted) using the second vibrating loading machine 7.
The furnace in the end wall 2 of the casing 1 has a burner device. The burner device used is a gas four-mix injection rectangular burner 22, then a burner in which two mixers with a perforated hemisphere are placed in the bottom row, producing a flame 0.7 meters long, and in the top row there are two mixers with twelve fins at the end of each mixer on the inner side, which, when burning a gas-air mixture, have a flame 2.5 meters long. Moreover, the proposed burner contains a flame-stabilizing tunnel 23, a refractory ramming mass 24, four mixers 25, united by a common welded gas distribution chamber 26, in each mixer 25 four nozzles 27 are drilled at an angle of 26 degrees to their axes, and the lower mixers 25 are in the upper part there is a pipe 28 with a diameter of 62×10 mm and a length of 300 mm Fig. 3, 4. Each lower mixer 25 contains in the lower part a device for final mixing of the gas-air mixture, consisting of a divider 29, made in the form of a cone, a disk 30, a sleeve 31 and perforated hemisphere 32, and the upper mixers 25 are a pipe with a diameter of 90×10 mm. The divider 29 has peripheral holes at an angle of 28 degrees to the axis of the mixer 25 for the passage of the gas-air mixture from the pre-mixing chamber 33 through them, in addition, the disk 30 has a hole in the center, the perforated hemisphere 32 has a rim for fixing, holes with a diameter of 2.5 mm in it is drilled in different directions in a checkerboard pattern. A welded steel casing 34 is welded to the end of the gas distribution chamber 26, which serves to fill the burner with refractory ramming mass 24. Gas is supplied to the gas distribution chamber 26 through a fitting 35. The flame-stabilizing tunnel 23 has an inclined partition 36, which serves as a guide and allows it to be received from the lower mixers 25 with a perforated hemisphere 32 flame melting the charge located closer to the burner, and from the two upper mixers flame melting the charge located in the middle of the furnace and closer to the end wall 2 farthest from the burner 22. In this case, the mixers 25, parts for the mixers and the cast the flame-stabilizing tunnel 23, placed on the gas distribution chamber 26 that unites the mixers and on the steel casing 34 of the burner 22, is made of heat-resistant cast iron ChYUKhSh. Heat-resistant cast iron allows you to increase the service life of the burner and, naturally, the stove.
The furnace design includes a mechanism for rotating the burner shield 37, which is a round steel plate with a diameter of 420 mm and a thickness of 8 mm Fig.1. Burner 22 is welded in the center into the burner shield 37. Column 38 of the rotation mechanism of burner shield 37 is attached to the foundation with four anchor bolts (not shown). In column 38, a shaft 40 is rotated at an angle of 100° from the hydraulic cylinder 39 with a bracket 41 attached to it and welded to it has a pipe 42 through which gas is supplied from the gas pipeline 43 to the burner 22. The hydraulic cylinder 39 is rigidly fixed to the support 44, and its rod 45 is pivotally connected to the rod 46, which is welded to the bracket 41. The burner shield 37 is welded to the bracket 41. Gas through the pipe 47 is supplied to burner 22, where it burns, and the flue gases generated during the smelting process are removed through probe 48 into the dust and gas purification system. It is important to note that in the side view (on the front) the mechanism for rotating the burner shield 37 is not shown in Fig. 1. The burner shield rotation mechanism introduced into the furnace design allows for improved working conditions for the furnace operating personnel. A very important fact is that the rotation mechanism of the burner shield 37 allows you to quickly replace a worn-out burner without disassembling the furnace; in addition, through the window into which the burner is inserted, alloying, refining of the liquid alloy, and also processing with fluxes can be carried out.
The furnace is lined with lightweight fireclay bricks, grade ShL 0.9, rib wedge item No. 44, 45.
A refractory solution is used as a binder, consisting of refractory clay (20%), fireclay powder (75%), liquid glass (3%) and foscon (alumina-chromophosphate mixture, 2%) Fig.2. The thickness of the seams is 1-2 mm, temperature compensation seams are not laid out. For lining, casing 1 is removed from rollers 10, placed in a vertical position, one end wall 2 is unscrewed. First, a heat-insulating layer is placed on casing 1, consisting of three sheets of flexible heat-insulating glass fiber mullite-silica cardboard 49, then a layer of lightweight fireclay 50 is lined on it. a layer consisting of three sheets of flexible heat-insulating glass fiber mullite-siliceous cardboard 49 and a layer of lightweight fireclay 50 helps reduce heat loss to the environment, and also allows you to further maintain the temperature of the metal in the furnace. A layer of lining made of mullite non-shrinkable ramming mass 51 is stamped onto the lightweight fireclay layer 50 according to a pattern. The thermal insulation layer, consisting of three sheets of flexible thermal insulating glass fiber mullite-siliceous cardboard 49, is laid on a refractory composition consisting of fireclay 30%, fireclay powder 62%, liquid glass 5%, foscona. The durability of the lining made of mullite non-shrink ramming mass 51 is relatively high - more than 690 heats. The service life of the furnace is increased due to the use of mullite non-shrink ramming mass, which has high fire resistance and durability.
The furnace is designed to operate on natural and artificial draft with a dust and gas purification system to achieve an environmentally friendly process. The dust and gas purification system is two-stage. The first stage includes: a mixing chamber 52, a smoke exhauster 53, a dust and gas purification unit 54. The second stage includes a cartridge filter 55. Work on natural draft is carried out in the case of repair of individual units of the dust and gas purification system. To dilute flue gases with shop air in order to reduce the temperature to 150-170°C, before feeding them into the smoke exhauster 53, a mixing chamber 52 is installed, which has two dampers: damper 56 regulates the draft (discharge in the furnace), damper 57 regulates the supply of shop air. The dust and gas purification system is equipped with a smoke exhauster DN-9u pos. 53, which supplies flue gases diluted with air to the dust and gas purification unit 54. The dust and gas purification unit 54 is a prefabricated cylindrical steel housing 58, in the lower part of which there is a rotating loading grid 59 with holes. Above the loading grid 59 there is a loading pipe 60. In the upper part of the cylindrical housing 58 there are rotating bag filters that collect dust particles from the flue gases (not shown). At the top of the dust and gas purification unit 54 there is a rotation drive for bag filters, consisting of an electric motor 61, a worm gear 62 and a plate 63.
In the upper part of the cylindrical body 58 on the frame 64 there is a blower 65 with an electric motor, the service platform 66 rests on four supports 67 and has a ladder 68 on the left. Spent adsorbent and dust are collected in the conical part 69 of the cylindrical body 58. The purified gases from the furnace are supplied to the dust and gas purification unit 54 through pipe 70. The operating principle of the dust and gas purification unit 54 is as follows: from the furnace, flue gases are pumped by a smoke exhauster DN-9u pos. 53 into pipe 70 and pass through the adsorbent layer under pressure, thereby forming a “fluidized layer”, resulting in harmful substances found in flue gases are adsorbed by slaked lime, silica gel and activated carbon. After cleaning the flue gases from harmful substances, they are cleaned of dust in rotating bag filters located in the upper part of the cylindrical housing 58. The purified gases are pumped into the cartridge filter 55 by a blower 65. The spent adsorbent is unloaded through the lower neck 71 of the cylindrical housing into a metal container and taken to the dump. . To remove dust on rotating bag filters, compressed air with a pressure of 0.6 MPa is used, which is supplied from the factory compressor station. Main technical characteristics of the dust and gas purification unit:
| - productivity for purified gas | 6000 m 3 /hour; |
| - filtering surface area | 11.7 m2; |
| - number of bag filters | 7 pcs; |
| - thickness of the adsorbent layer | 0.35 m; |
| - degree of purification for hydrogen fluoride | 62%; |
| - degree of purification for copper oxide | 84%; |
| - degree of carbon monoxide purification | 86%; |
| - degree of purification for nitrogen oxide | 84%; |
| - degree of purification for aluminum oxide | 82%; |
| - degree of dust cleaning | 90%; |
| - temperature of the gas being purified | from 20 to 100°C; |
| - temperature of the outer surface of the device | from 45 to 60°C; |
| - sound level no more | 80 dBA. |
The second stage of dust removal includes a cartridge filter 55. The cartridge filter 55 is welded from sheet steel and has a housing 72, inside of which 11 cartridges (not shown) are placed to capture fine dust. A hopper 73 is attached to the housing 72 of the cartridge filter 55 in the lower part for collecting fine dust, and a screw conveyor 74 is provided to remove fine dust from the hopper 73. The hopper 73 has two hatches 75. The housing 72 of the cartridge filter 55 with the hopper 73 rests on four supports 76, on the side of the housing 72 there is an inlet pipe 77, and on the end side of the housing 72 an outlet pipe 78 is welded. Dust from the cartridges is removed by a pulse of compressed air with a pressure of 6 ati, supplied from the compressor station through a pipe to six purge valves 79. For maintenance and To repair the cartridge filter, there are lower 80 and upper 81 service platforms and a ladder 82. The cartridge filter 55 has the following technical characteristics; productivity for purified gas 11000 m 3 /hour; number of filter elements 11 pieces; number of purge valves 6 pieces; thermal insulation thickness 30 mm; dimensions 2800×2000×3400 mm. Purification degree - 96%.
The principle of operation of the cartridge filter 55 is based on the capture of dust by cartridges as flue gases pass through them. As dust settles, the pores in the cartridges gradually become smaller. The bulk of dust does not penetrate into the cartridges, but settles on them.
As the thickness of the dust layer on the surface of the cartridges increases, the resistance to the movement of flue gases increases and the throughput of the cartridge filter 55 decreases, to avoid which dusty cartridges are regenerated with a pulse of compressed air. The purified flue gases, after passing through the cartridge filter 55, enter the chimney 83. It is important to note that the furnace can operate both on artificial draft and on natural draft. Behind the umbrella 48, the gas duct 84 bifurcates: one branch 85 (working on natural draft) has two dampers 86, 87 and goes to the chimney 83, the other to the mixing chamber 52, the smoke exhauster 53, the dust and gas purification unit 54 and, further, to the chimney 83 Fig.7. The branch of the boletus going to the smoke exhauster has 83 gates 88 in front of the chimney. Adjustment of the gates is not done so often, so an extension ladder is used to service them. The smelted metal is poured from the furnace along a rotary chute 89 into molds mounted on a casting carousel 90. The furnace operates on natural draft as follows.
The furnace is calcined after lining. The charge crushed on a shredder undergoes magnetic separation and is fed into the vibrating loading machine 7, the operator tilts the furnace towards the vibrating loading machine 7, while the working window 6 of the furnace should be opposite the loading tray of the vibrating loading machine 7. The operator turns on the drive to move the vibrating loading machine 7 forward, the vibrating loading machine 7 moves along the rail track 91 to the furnace and its tray enters the working window 6 of the furnace. The vibration mechanism of the vibrating loading machine 7 is turned on and the charge falls along the tray into the pre-calcined furnace. After loading the charge, the vibrating loading machine 7 is fed back along the rails 91, and the furnace is rotated to its original position. To increase the productivity of the furnace and increase the volume of metal output, the charge can be loaded into the furnace through the burner window (with the burner retracted) using the second vibrating loading machine 7 simultaneously. In this case, gates 86 and 87 on the gas duct 85 are open, and gates 56, 57, 88 are closed. The flame of burner 22 heats the scrap in the furnace to the melting temperature. The metal melts and accumulates in the furnace. After complete melting of the scrap loaded into the furnace, the burner 22 is withdrawn by the metal melter, flux is thrown into the furnace through the window where the burner was located, after treating the liquid metal with flux and confirming the grade of the resulting alloy by the spectral analysis laboratory, tap hole 8 is opened and the liquid metal flows through chute 89 , filling the molds located on the casting carousel 90. After pouring the liquid metal, the furnace is turned and the slag is downloaded along the toe of the working window 6 into the slag pit 92.
When the furnace is operating on artificial draft, when the dampers 86, 87 on the gas duct 85 are closed, and the dampers 56, 57 and 88 are open, the combustion products, having passed the mixing chamber 52, are diluted in it with shop air, then supplied to the dust and gas purification unit by a smoke exhauster 53. Flue gases are purified from harmful compounds in a “fluidized bed”, and in rotating bag filters they are purified from coarse and medium dust. Next, the blower 65 delivers them to the housing 72 of the cartridge filter 55, in which they are cleaned of fine dust and removed into the chimney 83.
The operation of the furnace on natural draft is carried out if the size of the sanitary protection zone of the enterprise allows, as well as when carrying out repair and maintenance work on the dust and gas purification system.
So, the proposed furnace is simple in design, it is used for processing (remelting) non-ferrous metal waste, in particular for processing aluminum scrap; the elements and devices introduced into the design make it possible to reduce emissions of harmful gases into the atmosphere, reduce heat loss to the environment, and also increase its service life.
1. A rotating drum melting furnace for processing non-ferrous metal waste, containing a cylindrical body, a burner device, a loading window, a tap hole for draining the molten metal, characterized in that it is equipped with a burner shield with a mechanism for its rotation, a drive mechanism for ensuring rotational movement of the furnace relative to the horizontal axis in both directions at an angle of 105° and a heat-insulating layer consisting of three sheets of flexible heat-insulating fiberglass mullite-siliceous cardboard and a layer of lightweight fireclay, on which is filled a layer of lining made of mullite non-shrink ramming mass, while the burner device is made in the form of a gas four-mix injection rectangular burner, in which in the bottom row there are two mixers with a perforated hemisphere, providing a flame 0.7 meters long, and in the top row there are two mixers with twelve fins at the end of the mixer on the inside, providing a flame 2.5 meters long, while the stove is made with the ability to work on natural and artificial draft with a dust and gas purification system, including a mixing chamber, a smoke exhauster, a dust and gas purification unit and a cartridge filter.
2. The furnace according to claim 1, characterized in that the mechanism for rotating the burner shield contains a column, inside of which there is a shaft, with the ability to rotate at an angle of 100° from the hydraulic cylinder, a bracket rigidly fixed to the shaft with a pipe welded to it for supplying gas from the gas pipeline to a gas four-mix injection burner and a burner shield welded at the end of the bracket, wherein the mechanism for rotating the burner shield is configured to load the charge into the furnace through the burner window with the burner retracted using a vibration loading machine.
3. The furnace according to claim 1, characterized in that the gas four-mix rectangular injection burner contains a flame-stabilizing tunnel, a refractory ramming mass, four mixers united by a common welded gas distribution chamber, in each mixer four nozzles are drilled at an angle of 26 degrees to their axes, wherein the lower mixers are in the upper part a pipe with a diameter of 62×10 mm and a length of 300 mm, and in the lower part they contain a device for final mixing of the gas-air mixture, consisting of a divider made in the form of a cone, a disk, a sleeve and a perforated hemisphere, and the upper mixers are a pipe with a diameter of 90×10 mm, while the mixers, parts for the mixers and the cast flame-stabilizing tunnel, placed on the gas distribution chamber connecting the mixers and on the burner casing, are made of heat-resistant cast iron ChYUKhSh.
4. The furnace according to claim 1, characterized in that the cartridge filter is designed to provide a purified gas productivity of 11,000 m 3 /hour, has 11 filter elements, 6 purge valves, a thermal insulation thickness of 30 mm, a purification degree of 96% and dimensions of 2800 ×2000×3400 mm.
Similar patents:
The invention relates to the field of industrial heat power engineering and can be used in the production of activated carbon. The method of activating coal particles fractionated by size is carried out by their continuous pouring and interaction with a countercurrent torch in a reactor inclined relative to the horizontal plane with heating, release and burning of volatile substances, formation and removal from the reactor of a mixture of volatile substances and combustion products, subsequent pouring and cooling with a countercurrent flow of products combustion in a cooler inclined relative to a horizontal plane and afterburning of volatile substances and discharge of combustion products into the atmosphere.
The invention relates to an inclined rotating reactor for burning solid household and industrial waste and drying bulk materials. The reactor contains a cylindrical body installed on a fixed support with the possibility of rotation, in the lower part of which there are at least two holes for unloading material with dampers configured to open in their lower position and close in their upper position relative to the vertical under the influence of their own weight when the reactor rotates .
The invention relates to furnaces for melting metal-containing waste and applying metal coatings using the thermal diffusion method and can be used for extracting non-ferrous metals from mixtures and oxides and treating the surfaces of parts.
The invention relates to the technology of firing building materials and can be used in the production of expanded clay. The method of firing expanded clay in a rotary kiln includes setting the required values of the expanded clay temperature at the point corresponding to the end of the heating zone, and the temperature at the point corresponding to the middle of the swelling zone, determining the temperature at the point corresponding to the end of the heating zone, and the temperature at the point corresponding to the middle of the swelling zone, determining the difference between the required and available value of the expanded clay temperature at the point corresponding to the end of the heating zone, forming a control action on the belt feeder drive as a function of the difference in these temperatures, determining the difference between the required and available value of the expanded clay temperature at the point corresponding to the middle of the swelling zone, forming functions of the magnitude of the difference between these temperatures of the control action on the furnace burner, additionally set the required value of the expanded clay temperature at the point corresponding to the end of the drying zone, determine the temperature at the point corresponding to the end of the drying zone, determine the difference between the required and available value of the expanded clay temperature at the point corresponding to the end of the zone drying, form a control effect on the furnace rotation drive as a function of the magnitude of the difference between these temperatures. The invention also relates to a device for firing expanded clay. The technical result is an increase in the quality of expanded clay, including its strength, a reduction in the amount of technological waste in the production of expanded clay, and stabilization of the firing process. 2 n.p. f-ly, 2 ill.
The invention relates to the design of a blast furnace tap hole for the production of cast iron. The device contains heat-resistant bricks located along the inside of the furnace casing, a cylindrical housing extending through the furnace casing and facing the heat-resistant bricks, and an annular sealing assembly located at the end of the housing next to the heat-resistant bricks and containing a housing seal. In this case, the body seal is located to provide an airtight seal of the body along its periphery, and the brick seal is located to provide an airtight seal of the bricks along the entire periphery between the heat-resistant bricks and the sealing unit. The invention is aimed at eliminating gas leakage during the production of liquid cast iron. 5 salary f-ly, 8 ill.
The invention relates to a rotary inclined furnace for processing aluminum scrap. The furnace contains a lined body with a support ring, which is supported on two rollers, a burner shield with a gas injection burner mounted on it with eleven mixers, a rotary lined bowl with two lined chutes, a furnace rotation drive and a burner shield inlet and outlet drive. The lined body has a heat-insulating layer consisting of a heat-insulating glass-fiber mullite-silica felt and a layer of lightweight fireclay, on which is filled a layer of lining made of mullite-siliceous ramming mass with a crust crust. The burner contains a device for regulating air flow, installed with an inclination of 20° to the axis of the lined body with the possibility of supplying gas to the burner through a pipe welded to a bracket mounted on a rotary column. The furnace has a rotating lined bowl mounted on a trolley with two lined chutes, and one of the two lined chutes has a chute attached to it from below, which can move from below the upper one to increase or decrease the length of the joined chutes, the trolley moves along rails to the lined body and back using electric drive, rotating frame, in working position supported on the front and rear supports of the rotating frame, the furnace is designed to operate on natural and artificial draft with a two-stage dust and gas purification installation to achieve an environmentally friendly process. This ensures an increase in the service life of the furnace, a reduction in heat loss and harmful emissions into the atmosphere. 6 salary f-ly, 12 ill.
The invention relates to continuous firing furnaces for heat treatment of material under a controlled gas atmosphere and heating temperature in continuous operation and constant mixing of the material, in particular to a screw-tube furnace. The screw-tube furnace contains a heat-insulating body, electric heaters, a retort pipe equipped with loading and unloading chutes, a pipe for air supply/intake and an uptake; a screw located inside the retort pipe and configured to rotate from an electric drive; a gas duct, a dust collection system and an instrumentation system, while the retort pipe is made with a diameter of 1.4-2.5 times larger than the diameter of the screw with the formation of an above-screw space inside the retort pipe. The screw-tube furnace can be made in two, three or four stages. Provides the ability to process both powder and finely dispersed materials with humidity up to 70% abs. and a content of combustible and volatile components from 5 to 95%, while dust removal is ~0.5% of the load. 2 n. and 16 salary f-ly, 4 ill.
The invention relates to a rotating melting furnace for processing waste non-ferrous metals, in particular aluminum scrap. The furnace contains a cylindrical body, a lining having a heat-insulating layer consisting of three layers of flexible heat-insulating glass fiber mullite-siliceous cardboard and a layer of lightweight fireclay, on which is filled a layer of lining made of mullite non-shrinkable ramming mass with a crust crust, two loading holes made in the front and rear end walls a furnace, a tap hole for draining molten metal and a tap hole for draining slag, and a burner device, characterized in that the burner device is made in the form of two gas injection cylindrical burners fixed in covers covering the loading holes, with each of the mentioned burners having twelve mixers, five of which are equipped with nozzles, placed at the top at the installation site in the covers of the loading holes of the furnace to provide a flame 2.4 m long, and seven mixers without nozzles are designed to provide a flame 1.5 m long when burning the gas-air mixture, while the furnace has mounted on the trolley there are two rotary lined chutes with welded lined bowls and with the ability to move them on the trolley along rails to the tap hole for draining the molten metal and back using an electric drive, and in each lid covering the loading hole there is a gas duct, and the furnace is designed to operate on natural and artificial draft with a two-stage dust and gas purification system, providing an environmentally friendly process and including a mixing chamber, a smoke exhauster, a two-section gas purification unit and a cyclone unit. This ensures low heat loss, increased productivity and increased service life of the furnace. 4 salary f-ly, 10 ill.
The invention relates to a method for primary processing of raw materials used in phosphoric acid production technology. The method includes the following steps: (1) primary processing of raw materials, (2) preparation of the inner sphere of granules, (3) molding of composite pellets, (4) restoration of composite pellets using the furnace method, and (5) hydration and absorption of phosphorus. The technical result consists in providing an energy-saving, environmentally friendly and highly efficient process that allows one to obtain high-quality phosphoric acid. 12 salary f-ly, 20 ill.
The invention relates to a rotating drum melting furnace for processing non-ferrous metal waste, in particular scrap aluminum. The furnace contains a cylindrical body, a burner device, a loading window, a tap hole for draining the molten metal, a heat-insulating layer consisting of three sheets of flexible heat-insulating glass fiber mullite-silica cardboard and a layer of lightweight fireclay, on which is packed a layer of lining made of mullite non-shrinkable ramming mass, the burner device is made in the form gas four-mix injection rectangular burner, in which two mixers with a perforated hemisphere are placed in the lower row, and in the upper row there are two mixers with twelve fins at the end of the mixer on the inside. The furnace has a mechanism for rotating the burner shield, with the ability to load the charge into the furnace through the burner window with the burner retracted, a drive mechanism for rotating the furnace relative to the horizontal axis in both directions at an angle of 105, a dust and gas purification system containing a mixing chamber, a smoke exhauster, a dust and gas purification unit and a cartridge filter . The design is simple, the service life is increased, and emissions of harmful gases into the atmosphere are reduced. 3 salary f-ly, 7 ill.
The method of reaction smelting in a short-drum furnace began to be used relatively recently in Germany for the processing of rich lead concentrates containing at least 65-75% Pb, and some intermediate products of lead production.
The smelting method in short-drum furnaces is used at a plant in Okere (Germany), where there are 4 such furnaces, in the GDR, at several plants in Poland and at some European plants. Sometimes a drum furnace is structurally significantly modified (lengthened) and called a Dershl furnace.
To study the physicochemical foundations of the process of direct reduction of lead in Germany, experimental smelting of a mixture of PbS, PbO and PbSO4 specially prepared in stoichiometric proportions was carried out.
Based on the work carried out, the following conclusions were made;
1) as a result of heating the PbS - PbO mixture, the reaction PbS + 2PbO = 3Pb + SO2 occurs at a temperature of 920 ° C, and the pressure of SO2 reaches 1 at (1 * 10v5 n).
2) a significant reaction rate between PbS, on the one hand, and PbO or PbSO4, on the other, is achieved only after bringing the corresponding mixtures to a liquid state;
3) the highest reaction rate in both cases is achieved at 920° C; at this temperature and pressure SO2 1 at (1*10v5 n) metallic lead is intensively released.
Thus, the researchers found that reaction smelting should be carried out at a higher temperature.
To prepare the concentrate for smelting, it is advisable to subject it to a single-stage agglomerating roasting with as few additives as possible so that the PbS-PbO-PbSO4 ratio in the agglomerate is within the limits required for reaction smelting.
Agglomeration firing can be carried out either with air suction from top to bottom, or with air supplied under pressure from bottom to top. The latter method has a number of advantages, especially when processing rich lead concentrates.
The following results were obtained during agglomeration firing:
The short-drum furnace is a riveted steel casing lined with high-alumina brick of the composition, %: 65-70 Al2O3; 20-25 SiO2; 3TiO2; 5Fe2O3; 0.5CaO. Lining thickness 250 mm. Between the furnace casing and the refractory lining there is a compacted layer of plastic clay 50 mm thick in case the lining expands when it is heated.
The furnace is driven by an electric motor with slip rings of three-phase current, 1000-500 rpm. Electric motor power 9 kW.
The general view of the furnace is shown in Fig. 76, and the sections are in Fig. 77.
Basic data of short drum furnace
The furnace is heated with brown coal dust. To improve the fuel combustion process, primary and secondary air are introduced into the furnace. Up to 50% of sulfur can be extracted from furnace gases in the form of sulfuric acid. The heat of the gases is used in a waste heat boiler: 2-2.5 g of steam are obtained per 1 g of pulverized coal. After the boiler, the gases are filtered in bag filters.
The smelting process is periodic. The charge is loaded into the furnace either in small portions so as not to reduce the temperature too much, after which the furnace is quickly heated to the temperature of intense reactions (1100 ° C), or the entire amount required for the operation is loaded immediately onto a layer of liquid lead or slag left in the furnace from the previous swimming trunks The bath is heated by the flame and the heat of the lining.
The furnace can rotate in two opposite directions at a speed of 0.5-1.0 rpm, which promotes good contact of materials and melting products and speeds up the process. The temperature is maintained during melting; coal dust flame 1600° C, the inner wall of the lining 1100° C, flue gas 1200° C. The flame changes direction in the furnace, and the exhaust gases exit it through the top of the same hole. Opposite the combustion opening there is a loading window, which is usually closed.
By the end of the smelting, its products (lead, speis, slag) are well separated by density in a furnace with a deep bath and are released separately.
Some of the heat from the hot furnace gases is used in the recovery boiler to produce steam. Sulfur can be recycled to produce sulfuric acid at a rate of -50%. No fluxes are required for smelting, and the capital costs of building a plant using this method are lower than the costs of the shaft smelting method.
Purpose of the drum furnace
The purpose of this rotary kiln is to heat the feed material to a maximum temperature of 950 °C. The design of the equipment is based on the process conditions outlined below in a rotary kiln.
| Raw materials Raw material Feed rate Raw material moisture Raw material temperature Specific heat capacity of raw materials Bulk density of raw materials |
uranium peroxide (UO 4 . 2H 2 O) 300 kg/h 30 wt. % 16 °C 0.76 kJ/kg K 2.85 g/cm³ |
| Product Product material Product feed rate Product moisture content (wet mass) Product temperature: on the discharge side of the kiln on the discharge side of the cooler Specific heat capacity of the product Bulk density of product material Particle size |
uranium oxide (U3O8) 174.4 kg/h ≈ 0 wt.% 650 – 850 °C |
| Furnace power consumption | 206 kW |
| Drum rotation speed range normal |
1-5 rpm 2.6 rpm |
The material is heated in the following heat transfer modes, listed in increasing order of importance:
1. Heat of radiation.
2. Heat from direct contact with the inner surface of the drum.
The required amount of heat is determined taking into account the following requirements:
1. Heat to increase the temperature of solid components.
2. Heat to heat the wet feed material to evaporation temperature.
3. Heat to evaporate the wet feed material.
4. Heat to increase the temperature of the air stream.
Description of the drum furnace process
The wet cake (UO 4 . 2H 2 O) is placed on the kiln loading conveyor. The loading side of the drum is equipped with screw plates and a feed pad, which removes material from this side of the drum at high speed. Immediately after leaving the screw plates, the material flows down along the longitudinal axis of the drum under the influence of gravity. In the furnace section of the kiln, hydrated uranium peroxide (UO 4 . 2H 2 O) is heated using the electric heating elements of the furnace. The electric oven is divided into three temperature control zones, providing flexible temperature control. In the first two zones, uranium peroxide (UO 4 . 2H 2 O) is gradually heated to a temperature of about 680 °C. In the third zone, the temperature rises to approximately 880 °C, and uranium peroxide (UO 4 . 2H 2 O) is converted into uranium oxide (U3O8).
The fully reacted yellow uranium cake (U3O8) is fed into the cooling section of the drum. Heat is removed from the solid components, due to high thermal conductivity, through the wall of the kiln drum and is removed with cooling water sprayed onto the outside of the drum. The material temperature is reduced to approximately 60 °C, then the material is fed into the discharge pipeline, through which it enters the transport system by gravity. Through the discharge pipe, a powerful flow of air is supplied to the rotary kiln, passing through the drum towards the flow of material to remove water vapor formed during the heating stage of the process. Humid air is removed from the loading pipe using ventilation.
Rotary Kiln Components
Rotary kiln drum
The welded sections of the drum have seams located alternately at angles of 90° and 180° to one another and obtained by welding with complete penetration of the base metal. The tires and ring gears are mounted on machined surfaces separated from the drum by spacers to accommodate differences in radial thermal expansion. The drum design takes into account any thermal and mechanical loads and therefore ensures reliable operation. On the loading side of the drum there are material-retaining linings that block the reverse flow of material into the pipeline and screw plates for feeding material into the heated sections.
The open sections of the drum on the loading and unloading sides are equipped with thermal protection screens for personnel.
Bandage
The drum has two tires without welds and joints made of forged steel. Each band has a solid rectangular section and is reinforced for long service life.
Support wheels
The furnace drum rotates on four support wheels made of forged steel. The support wheels are reinforced for increased service life. The wheels are mounted with tension on a high-strength shaft mounted between two bearings with a service life of at least 60,000 hours. The wheel base is equipped with push screws for horizontal wheel alignment and adjustment.
Thrust rollers
The unit contains two thrust rollers, consisting of two steel wheels with sealed spherical roller bearings, which have a service life of at least 60,000 hours. The thrust rollers are reinforced to increase their service life.
Drive unit
The drum is designed to rotate at a frequency of 1-5 rpm with a power of 1.5 kW from an electric motor with a rotation speed of 1425 rpm, operating from a three-phase alternating current network with a voltage of 380 V, a frequency of 50 Hz and made in a sealed design with air cooling. The electric motor shaft is directly connected to the input shaft of the main gearbox through a flexible coupling.
The cycloidal main gearbox has a precise reduction ratio of 71:1 with one reduction stage. The low-speed gearbox shaft is designed for the required torque and maximum loads.
Preventing Kiln Drum Deformation
To prevent deformation of the furnace drum during failures in the electric motor power supply system, an additional diesel engine is provided to continue rotating the drum. The diesel engine has a variable speed (1500-3000 rpm) and a rated output power of 1.5 - 3.8 kW. The diesel engine is started manually or by a DC electric starter and is directly connected to the electric motor shaft through a coupling.
Drum kiln">
Ring gear
The ring gear is made of carbon steel. Each sprocket has 96 hardened teeth, is mounted on a drum and has connectors for easy removal.
Drive gear
Made from carbon steel. Each gear has 14 hardened teeth and is mounted on a low-speed gearbox shaft.
Drive chain
An inclined chain is used to ensure the rotation of the kiln drum.
Kiln system
The furnace casing encloses the drum and is made of carbon steel. The walls and floor of the casings are made as one complete section. The oven roof consists of three sections, one for each heating zone, and can be removed for oven or drum maintenance.
Characteristics of the chamber/heating elements:
Nozzle water cooler
Nozzle water cooler - reduces the temperature of the furnace product. The cooler body is made of carbon steel with internal surfaces coated with epoxy resin (to reduce corrosion). The housing is equipped with two top-mounted piping having spray nozzles, inlet and outlet rotating labyrinth seals, an upper steam outlet nozzle, a lower drain nozzle, a side bypass nozzle, access doors and inspection holes. Water is supplied to the spray nozzles through a pipeline and discharged by gravity through the bottom drain flange. 
Screw feeder
The roasting furnace is equipped with a loading screw conveyor for feeding uranium peroxide cake into the drum; it is a screw located at a zero angle to the horizontal, subjected to finishing processing.
Kiln thermocouples
Thermocouples are provided to continuously monitor the temperature in the oven zones and the temperatures of the discharged product.
Zero speed switches
The kiln is supplied with two zero speed switches, one of which continuously controls the rotation of the drum, the other - the rotation of the loading screw line. The rotation frequency switch assemblies are mounted on the ends of the shafts and are of the type of disk pulse generators that create an alternating magnetic field that is recorded by the measuring device.
