Multi-chamber melting furnace and method for melting non-ferrous scrap metal

Abstract

A multi-chamber melting furnace for melting scrap of non-ferrous metals, in particular aluminum scrap, including a first shaft furnace with a shaft for charge material, in which impurities of the charge material can be removed, and at least one furnace chamber which is connected to the shaft of the first shaft furnace and has a first heat supply device, wherein at least one second shaft furnace with a shaft for charge material, in which shaft impurities of the charge material can be removed, the furnace chamber being connected to the shaft of the second shaft furnace and being arranged between the shafts in such a manner that the furnace chamber forms a main melting chamber in which the molten bath is located during operation.

Claims

1. A multi-chamber melting furnace for melting scrap of non-ferrous metals comprising a first shaft furnace with a shaft for charge material, in which impurities of the charge material can be removed, and at least one furnace chamber which is connected to the shaft of the first shaft furnace and has a first heat supply device, wherein at least one second shaft furnace with a shaft for charge material, in which impurities of the charge material can be removed, the furnace chamber being connected to the shaft of the second shaft furnace and being arranged between the shafts in such a manner that the furnace chamber forms a main melting chamber in which a molten bath is located during operation, wherein the shafts are arranged in such a manner that charging is effected by the weight force of the charge material directly into the molten bath, and wherein a lifting and lowering device is connected to the furnace chamber for adjusting an inclination angle of the furnace chamber.

2. The multi-chamber melting furnace according to claim 1, wherein the furnace chamber and the lower end of the shafts are directly connected to each other.

3. The multi-chamber melting furnace according to claim 1, wherein the furnace chamber and the shafts are arranged laterally next to each other.

4. The multi-chamber melting furnace according to claim 1, wherein the furnace chamber and the shafts each have longitudinal sides adjoining each other, the furnace chamber and the shafts being connected to each other along the entire longitudinal sides.

5. The multi-chamber melting furnace according to claim 1, wherein the furnace chamber and the shafts form a continuous common furnace floor.

6. The multi-chamber melting furnace according to claim 1, wherein the shafts are designed such that they are free of internal components in such a manner that the charge material is fed directly into the molten bath.

7. The multi-chamber melting furnace according to claim 1, wherein the shafts each have a second heat supply device.

8. The multi-chamber melting furnace according to claim 1, wherein an agitator is associated with the furnace chamber.

9. A method for melting scrap of non-ferrous metals wherein charge material is fed through at least two shaft melting furnaces to a furnace chamber designed as a main melting chamber, wherein organic impurities of the charge material are removed in the shaft melting furnaces and the charge material is transferred directly from the shaft melting furnaces into the furnace chamber designed as a main melting chamber, wherein the shafts are arranged in such a manner that charging is effected by the weight force of the charge material directly into the molten bath, and wherein a lifting and lowering device is connected to the furnace chamber for adjusting an inclination angle of the furnace chamber.

10. The multi-chamber melting furnace according to claim 8, wherein the agitator is an electromagnetic agitator.

Description

(1) In the figures

(2) FIG. 1 shows a longitudinal section of a multi-chamber furnace according to an exemplary embodiment according to invention in the area of the furnace chamber;

(3) FIG. 2 shows a longitudinal section of the multi-chamber furnace according to FIG. 1 in the area of the shaft furnace;

(4) FIG. 3 shows a cross-section of the multi-chamber furnace according to FIG. 1;

(5) FIG. 4 shows a longitudinal section of the multi-chamber furnace according to FIG. 1 in the area of the shaft furnace in the non-tilted state, and

(6) FIG. 5 shows a perspective top view of the multi-chamber furnace according to FIG. 1 with the furnace doors open.

(7) The multi-chamber furnace according to FIGS. 1 to 5 is used for the production of secondary aluminum from aluminum scrap. Both clean and contaminated aluminum scrap can be processed. Any impurities, in particular organic impurities, such as lacquers or oils, are burned by the exhaust gases produced during the melting process and are removed before melting. The processing of scrap from other non-ferrous metals is possible.

(8) The multi-chamber furnace includes a first shaft furnace 10 and a second shaft furnace 14. A furnace chamber 12 is arranged between the two shaft furnaces 10 and 14. The shaft furnaces 10, 14 and the furnace chamber 12 together form the multi-chamber furnace. The shaft furnaces 10, 14 are in fluid communication with the furnace chamber 12 so that heat and material transfer between the shaft furnaces 10, 14 and the furnace chamber 12 is possible. The furnace chamber 12 forms the main melting chamber, into which the heat required for melting or at least a large amount of the heat required for melting is introduced during operation. The furnace chamber 12 comprises a first heat supply device 13 for this purpose. The latter may comprise one, two or more burners, in particular gas burners, or an electric heater, which can be clearly seen in FIGS. 3 and 5. The furnace chamber is made of a refractory material in a manner known per se.

(9) The furnace chamber 12 has a trough-shaped furnace floor 16, which receives the molten bath 22 during operation. On the opposite side of the furnace floor 16, the furnace chamber is bounded by a furnace ceiling 21. In the furnace ceiling 21, openings are formed for the shaft furnaces 11, 14. The furnace chamber 12 has a rear wall 30 to which the burners are attached, which apply heat to the furnace chamber 12 through openings in the rear wall 30. The burners are inclined downwards. Furthermore, on the rear wall 30, the discharge spout 29 is formed. The latter can be designed as a tapping valve for a stationary furnace or as an outlet nozzle for a swiveling furnace. The figures show a swiveling furnace, the rear wall 30 of which is provided with swivel joints 27 which form a horizontal axis of rotation around which the entire furnace can be swiveled, e.g. through an angle of 23°. Other angles are possible. A lifting and lowering device 19 forms the swivel drive and is connected to the furnace floor at a distance from the swivel joints 27. The lifting and lowering device 19 can be formed by one or more hydraulic cylinders which engage at the furnace bottom at a side of the furnace, as shown in FIGS. 3 and 5. Other swivel drives are possible.

(10) The side of the furnace opposite the rear wall provides access to the furnace chamber 12 and is closed during operation by furnace doors 20. As can be seen in FIG. 3, three furnace doors 20 are provided which are associated with the shaft furnaces 11, 14 and the middle furnace chamber 12. The width of the doors 20 corresponds approximately to the width of the shaft furnaces 11, 14 or the furnace chamber 12.

(11) The shaft furnaces 10, 14 are substantially identical. Each shaft furnace 10, 14 has a shaft 11, 15 into which the charge material, i.e. aluminum scrap, can be inserted. Usually, scrap packages are charged. The furnace chamber 12 and the lower end of the shafts 11, 15 are directly connected to each other. The furnace chamber 12 and the melting chambers arranged at the base of the shafts 11, 15 form a continuous common chamber which is filled with melt during operation.

(12) The shafts 11, 15 have inner and outer side walls 23, 24. The outer side walls 24 of the shafts 11, 15 also form the outer side walls of the furnace chamber 12. The inner side walls 23 extend parallel to the outer side walls 24 and end at a distance from the furnace floor 16 in order to create the fluid communication between the shaft furnaces 10, 14 and the furnace chamber 12. The furnace floor 16 extends over the entire width of the furnace at approximately the same height and forms a common floor for the shaft furnaces 10, 14 and the furnace chamber 12. The rear wall 30 of the furnace chamber 12 also forms the rear wall of the shafts 11, 15. During operation, the shafts 11, 15 are covered by a shaft closure 28, which can be removed for charging.

(13) As shown in FIG. 3, the furnace chamber 12 and the shafts 11, are rectangular in cross-section and each has longitudinal sides that adjoin each other. The furnace chamber 12 and the shafts 11, 15 are in fluid communication with each other along the entire longitudinal sides.

(14) As can be seen in FIG. 2, the shafts 11, 15 are free of internal components so that the charge material can sink directly onto the furnace floor 16. The furnace is pumpless, i.e. it can be operated without a melt pump. It is possible to add a melt pump. The shafts 11, 15 have second heat supply devices which are designed as burners inclined obliquely downwards. Other heating elements are possible.

(15) The furnace stands on a foundation 26 in which an electromechanical agitator 28 is embedded. In the melting operation (FIGS. 4, 5) the agitator 28 is located below the middle furnace chamber 12, i.e. in the middle of the furnace.

(16) As shown in FIG. 5, at least one of the shafts 11, 15 (here the right shaft 15) can be designed to be removable. This has the advantage that one of the shaft furnaces can be shut down temporarily if the scrap available for melting is not sufficient for simultaneous operation with two shaft furnaces 10, 14. The second shaft furnace 14 is then closed (FIG. 5).

(17) The multi-chamber furnace works as follows.

(18) For starting up or melting clean aluminum scrap, the furnace can be charged via access 25. For this purpose, at least the middle furnace door 20 is opened, as shown in FIG. 5. During melting operation, contaminated aluminum scrap is fed-in via shafts 11, 15, is heated in shafts 11, 15 and decreases in weight as the aluminum scrap liquefies and sinks at the shaft base due to its weight force. In the process of this, impurities in the scrap are burned and thus removed before the respective batch reaches the shaft base and is immersed in the molten bath. Heating is effected by the exhaust gases produced during melting, which rise upwards in shafts 11, 15. Heating in shafts 11, 15 can be increased by the second heat supply devices 17.

(19) The furnace chamber 12 functions as the main melting chamber because the molten bath 22 is permanently heated there to generate the required melting energy for the scrap that is immersing into the molten bath 22 in the area of the shafts 11, 15. During melting operation, the molten bath 22 is moved by the electromagnetic agitator 18.

(20) To remove the melt, the furnace is either tapped off at the discharge spout 29 or tilted (FIGS. 1, 2) so that the melt can flow out of the discharge spout 29.

REFERENCE LIST

(21) 10 first shaft furnace

(22) 11 shaft

(23) 12 furnace chamber

(24) 13 first heat supply device

(25) 14 second shaft furnace

(26) 15 shaft

(27) 16 furnace floor

(28) 17 second heat supply device

(29) 18 agitator

(30) 19 lifting and lowering device

(31) 20 furnace doors

(32) 21 furnace ceiling

(33) 22 molten bath

(34) 23 inner side walls

(35) 24 outer side walls

(36) 25 access

(37) 26 foundation

(38) 27 swivel joints

(39) 28 shaft closure

(40) 29 discharge spout

(41) 30 rear wall