WO2011055402A1

WO2011055402A1 - Completely modular plant for melting and casting aluminium from scrap material

Info

Publication number: WO2011055402A1
Application number: PCT/IT2010/000444
Authority: WO
Inventors: Antonio Spoleto
Original assignee: Hitech Srl.
Priority date: 2009-11-09
Filing date: 2010-11-08
Publication date: 2011-05-12
Also published as: ITRM20090576A1; IT1396275B1

Abstract

Aluminium melting plant for the production of ingots for foundry, characterized by the fact that it is completely modular, in which every module, melting furnace, waiting basin, joint for the distribution of liquid metal, systems for loading scrap iron and retrieving slag, ducts of adduction smoke, ingot moulds, ladders and decks are stackable each other or detachable and transportable with standard means of transport, and such that the positioning of the melting furnace is risen from the floor plan and positioned on parallelepiped, metallic, modular and modular bodies with a rectangular base, to form a shop floor to which decks are associated in order to widen the workspace and which can be accessed by means of ladders or hoists and on which and within which it is possible to position the accessory equipment for loading scrap iron and retrieving slag, smoke ducts and piping for the water, electrical and fuel system.

Description

COMPLETELY MODULAR PLANT FOR MELTING AND

CASTING ALUMINIUM FROM SCRAP MATERIAL

Description Technical Field The purpose of the present invention is a system for the casting of metallic materials, especially aluminium scrap, characterized in that each component, the melting furnace, the basin or the spherical waiting basin, the distribution joint of the molten material, the smoke escape system, the shop floor, the elevators, the decks or the ingot moulds are constructed with a module capable of connecting removably to other modules through bolts, to form the foundry plant, so that the plant, once it is formed to assemble the modules, can also be dismantled and transported on standard means of transport.

State of the art In patent No. EP1334324, the applicant describes a melting system with a spherical waiting basin and a rotary swivel connection to the static furnace. In particular, the rotary joint is characterized by the fact that the channel to discharge the liquid metal from the cupola into the spherical waiting basin consists of two properly insulated cylindrical bodies, fixed respectively by one end to the cupola and to the waiting basin, with the other end of each cylindrical body inserted coaxially one into the other, so that, through a motorized system, the waiting basin can freely turn to allow the escape of the molten metal from the outlet and the filling of ingot moulds; the spherical waiting basin consists of two hollow hemispheres, placed one on top of the other, with refractory and insulating walls, surrounded by a metal jacket, partially placed in a pit and supported by stands, so that its meridian circle is practically at the same height of the discharge channel.

In patent no. EP1608926, the applicant describes a system for melting primary and secondary aluminium by sorting and recycling waste, characterized in that it uses: a rotary furnace, equipped with an internal spiral element that realizes the melting of aluminium by not using a salt bath, an associated runner with a proper slope and properly enclosed in an insulated and window room that is placed between the orifice of the rotary furnace and the spherical waiting basin placed on a lower floor, in a pit, and fitted with a rotary joint so as to obtain a direct and continuous spill of molten metal into the waiting basin, an automatic and continuous sorting and recovery device of the furnace slag which is directly integrated in the system itself, and a double flue gas ducting system.

As we know, the realization of aluminium scrap melting system for the production of ingots for casting alloys, as well as the recasting of the same aluminium ingots is subject to a series of environmental standards; in practice, to obtain a permit construction of a melting plant is necessary to identify and assess the main environmental impacts that its realization can determine. Now it is known that the construction of a plant of the type considered will lead to a general construction site set up stage of the interested area by a preparation process of the area, including excavation operations for the installation of foundations, buildings, etc.. Therefore, the lower the distortion on the affected area for the implementation of the melting system, the greater the chance of having the building permits without delay. It has also to be considered that it is very helpful to be able to move easily the system into another place, if the conditions of the place are no longer acceptable, on account of subsequent environmental, economic or military issues.

Aims and advantages of the invention The main object of this invention is to overcome the drawbacks of the previous technique with a completely modular aluminium melting system to produce alloy ingots, so that each module is designed to ease the mounting with other modules, such that each module can be separated from each other or dismantled into smaller pieces for easy transport with conventional means of transport for the possible relocation into other places and also to ease the maintenance and the replacement of each module subject to wear.

Another object of the present invention in accordance with the previous one is to obtain a melting plant where the placement of the furnace is raised from the ground floor, through the implementation of metallic pieces with a rectangular base and modular units to form a shop floor which is accessible by stairs or elevator, and on which or within which it is possible to place the ancillary equipment to load the scrap, recover the slag, flue gas ducting and the pipes for the plumbing, electrical and fuel system.

Another object of the present invention in accordance with the previous one is to obtain a melting plant where the placement of the raised melting furnace does not allow to make excavations for the placement of the spherical waiting basin capable of achieving the optimum inclination of the discharge channel for the escape of molten metal from the melting furnace towards the waiting basin, so as to improve the safety and ease of installation and maintenance both of the sphere and of the system handling.

Another object of the present invention is to obtain an aluminium melting plant for the production of alloy ingots, in accordance with previous understandings, in which there is a direct and continuous spill of molten metal in a double catch basin without stopping the melting process in place, so as to achieve advantages in terms of the production volume of molten metal, fuel, labor and improve conditions as far as the work safety and the alloy quality are concerned.

Another object of the present invention is to obtain an aluminium melting plant for the production of alloy ingots, in accordance with previous understandings, in which there is a smoke evacuation system to minimize the waste of thermal energy in the melting furnace, while reducing heavy pollutants in flue gas before they are conveyed to the fire, and improve the breathing air quality for the workers in the plant, much better than plans of the previous technique.

Another object of this invention is to obtain a compact aluminium melting plant, in accordance with previous understandings, which uses a smaller area than the facilities located only above ground, so as to save on the land purchase costs.

Description of the drawings and how to achieve the invention

Additional features and advantages of the invention will be further obtained by the description of the preferred forms of execution, which are illustrated merely as an example and are not limited the to attached drawings.

Fig. 1 shows, in a three-dimensional view, the assembly of the melting system in its first embodiment, with the static furnace.

Fig. 2 shows the overall exploded design of a the melting furnace with the various components in the first embodiment of the static furnace.

Fig. 3 shows, in a three-dimensional view, the assembly of the melting system in a second embodiment, with its rotary furnace.

Fig. 4 shows the overall exploded design of a the melting furnace with the various components in the first embodiment with the rotary furnace.

Fig. 5a, 5b and 5c show respectively: the overall modular shop floor, a single module and its internal stiffening structure, according to the present invention. Fig. 6 shows the static melting furnace in a three-dimensional view.

Fig. 7 shows the static melting furnace in another three-dimensional view.

Fig. 8 shows a three-dimensional view of a section of the furnace static.

Fig. 9 shows a three-dimensional view of the rotary melting furnace.

Fig. 10 shows in a three-dimensional view a section of the rotary melting furnace with a coil, inner element.

Fig. 1 1 shows, in a three-dimensional view, a section of the outlet duct of the molten material and the joining to the spherical waiting basins.

Fig. 12a, 12b and 12c show various three-dimensional views of the spherical waiting basin with the supporting and handling platform.

Fig. 13a, 13b, 13c, 13d, and 13e show respectively the various pieces of the spherical components of the waiting basin.

Fig. 14 shows, in a three-dimensional, the smoke escape ducts.

In accordance with the drawings, with (1 ) it has been shown that the base module for creating the shop floor consists of a metallic rectangular parallelepiped body, whose sides are made of rectangular, sheet metal panels which are 15 mm thick (2), and which are centrally provided with a rectangular opening (3) with rounded smaller sides, which are joined by a riveting (4) to form the sidewalls (5) and (6) the roof decking (7), internally stiffened by laminar beams (8) and properly lightened with holes (9) along their longitudinal extent, while the base of the module consisting of a steel beams frame (10). Openings (3) on the sidewalls of the module are used to lighten the module but also as an access service for both facilities and staff. The sidewalls (5) are available only in modules that make up the whole terminal, that is only in exposed modules, in all intermediate modules these walls are removed. In some modules (1 1 a, 1 1 b, 1 1 c), the walls (6) have no openings, there being no need for the transit of equipment or personnel. The modules (1 1 a, 1 1 b, 1 1 c, 1 1 d) forming the plans (P2, P3) are longer, and the terminal modules (1 1 a, 1 1 d) have three openings on their side end surface (5), while the modules forming the plan (P1 ) have a reduced length, and terminal modules (1 1 e, 1 1f) have two openings on their lateral surface (5). On modules (1 1 g, 1 1 h, 1 1 s) is placed the melting furnace, which can be either rotary (12) or static (13). The module (1 1 h) is fitted on both sides (6) with a rectangular opening (14) which is properly adapted for connecting the flue pipe, which passes inside the modules, to the flue gas collecting duct (15) coming directly from the melting furnace. The flue gas collecting duct (15) is modular and can be connected by bolting the two sides, on two sides, both the rotary and the static furnace, and consists of a rectangular metal pipe with two inlets (16), which are connected to the smoke-exhaust windows of the melting furnace, and one outlet (17) which it is connected through the rectangular opening (14), to the flue pipe that passes through the modules. Brackets (18) serve to stiffen the overhang of the duct, and legs (19) are used to partially support the weight on the ground. The static type of the melting furnace (13) is made of iron sheets (20) suitably stiffened with ribs (21 ) and joined with bolts (22) or studs, lined internally with refractory bricks (23) and secured to the metal jacket (20) of the furnace through a refractory fire and heat resistant mortar. The furnace is fitted, on each of the two opposing sides, with two smoke-exhaust windows (26) and in the center with an inlet opening (24) for the scrap to be melted, brought up, on the shop floor, with hoists (27) and placed in the furnace by screw conveyors (25), on the other side of the furnace there are doors (28) for dumping of waste, which is passed through the grid (29), to start the selection and retrieval screws. On the other side, the furnace is equipped with an inlet for the burner flame, and below with an exit port (30) for the melted metal. It should be noted from Fig. 8 that the refractory bottom of the furnace is sloped in order to favour the escape of molten metal. The rotary furnace with the inner spiral element has been extensively described in patent no. EP1608926. It should be stressed that in this patent application, the furnace has been made more compact and modular in order to be integrated into the current plant, by providing its end with two parallelepiped bodies (31 ) and (32) which integrate respectively: the first body (31 ), the smoke-escape window (33) and the ventilation hood (34), the inlet (35) for scrap to be melted, and below the channel (36) for retrieving waste, and the second body (32), the smoke-escape window (37), the inlet (38) of the burner flame, and below the output channel of the molted metal. Above, the two bodies are connected by another parallelepiped hollow body (39). Also the spherical waiting basins have been described in patent No. EP 1334324 and EP1608926 of the same applicant, except that they were placed in a specially prepared pit, and the ball was being built in two halves.

In this new plant the sphere is made by joining four segments (40a, 40b, 40c, 40d) which are easily associated with bolting (and easily removable and transportable) and each of these is made externally by metal plates (41 ) which are 15 mm thick and assembled by welding. The sphere is internally insulated with a coating of refractory bricks, and impermeable to gases formed during the process. The spheres are equipped with an additional burner supplied with natural gas or LPG, with the function of maintaining a constant temperature of 700° C. The spherical waiting basin rests directly on the ground level, and placed at modules (1 11, 1 1 m,

1 1 n) on both sides, being two of the waiting basins used in the plant. The supporting platform that allows the rotation of the spherical waiting basin consists of a frame (42) with a square base of metal beams to which are attached metal vertical supports (43), suitably stiffened and reinforced with the interposition of transverse metal joists (44), which support the wheels (45) to form slide rails for the tilting supports (46) of the spheres. The connection between the melting furnace, either rotary or static, and the waiting spherical basin occurs through the diverter body or the distribution joint (47) of the molten metal.

The diverter body or the distribution joint (47) of the molten metal has a box-shaped hollow inlet (48) provided with flanged edges to be connected to the furnace by bolting, and a cross duct (49) whose ends have two cylindrical terminal mouths (50) with a circular base to enter the inlet mouth of the spherical waiting basin.

The distribution joint is constructed externally with sheet metal and the inner walls are lined with refractory bricks in order to obtain a good insulation and to minimize heat loss, to remove all these heat losses and their influence on the molten metal, the joint is further provided inside with hot plates (51 ) powered by natural gas or LPG, so that the molten metal in transit maintains the same temperature inside the melting furnace, in practice no less than 700 ° C. The distribution joint feeds both spherical waiting basins, but can also feed a single waiting basin.

The diverter serves another important function, that is to carry the exhaust gases that are formed in the spherical waiting basin directly into the melting furnace and then from this to the smoke escape system. In this way, since there is no continuity between the melting furnace and the waiting basin, there is less heat loss in the waiting basin and also an energy recovery on account of the heat of the exhaust gas in transit through the diverter, so that in many cases it is possible to do without using hot plates to maintain constant temperature.

The system is completed by scaffolding (52) that allow to create new raised shop floors, P4 and P5, at the melting furnace and at the spherical waiting basin. These shop floors are linked to shop floors P2 and P3, with a resulting increased surface. The lifting device (53) and the ladders (54) are used to reach these shop floors. Additional decks (55) provided with ladders (56) are used to reach the shop floor P1. On both sides of the shop floor there are ingot moulds (57) with one end reaching the spherical waiting basin to collect the molten metal.

Claims

1 ) Aluminum melting system to produce ingots from foundry, characterized by the fact that it is completely modular, in which every module, melting furnace, waiting basin, joint for the distribution of liquid metal, systems for loading scrap iron and retrieving slags, ducts of adduction smoke, ingot molds, ladders and decks, are stackable each other or detachable and transportable with standard means of transport, and such that the positioning of the melting furnace is risen from the land plan and positioned on parallelepipedal metallic, modular and componible bodies with a rectangular base, to form a work plan to which decks are associated in order to widen the workspace and which can be accessed by means of ladders or a freight elevator and on which and within which it is possible to position the accessory equipment for loading scrap iron and retrieving slags, smoke ducts and piping for the water, electrical and fuel system.

2) Aluminum melting system to produce ingots from foundry, as claim 1 ) characterized by the fact that the base module for composing the work plan has sides which are constructed with 15mm wide rectangular, metallic sheet panels, (2), they are supplied centrally with a rectangular opening (3) with rounded smaller sides, then they are joined by a riveting (4) to form the sidewalls (5) and (6) the flooring (7), inner hardened by laminar beams (8) specially lightened with holes (9) along their longitudinal extension, while the base of the module is formed by a chassis of metallic beams (10).

3) Aluminum melting system to produce ingots from foundry, as claim 1 ) and 2) characterized by the fact that the sidewalls (5) are only present in modules that form the assembly terminal, that is only in visual modules, while in all intermediate modules, the walls (5) are removed, and in modules (1 1 a, 1 1 b, 1 1 c) the walls (6) do not have openings, not being necessary the passage of systems or workers, while the modules (1 1 a, 1 1 b, 1 1 c, 1 1 d) that form the pians (P2, P3) are longer, and the terminal modules (1 1 a, 1 1 d) have three openings on their end lateral surface (5), while the modules that form the plan (P1 ) have a lesser length, and the terminal modules (1 1 e, 1 1 f) have two openings on their lateral surface (5). 4) Aluminum melting system to produce ingots from foundry, as claim 1 ) characterized by the fact that the module (1 1 h) is supplied on two sides (6) with a rectangular opening (14), formed for fixing the attachment of the smoke escape pipe, which passes in the inner modules, and in the smoke collecting line (15) coming directly from the melting furnace.

5) Aluminum melting system to produce ingots from foundry, as claim 1 ) characterized by the fact that the smoke collecting line (15) is modular and pluggable by means of riveting, on two sides, both to the rotary and static furnace, and is composed by a metallic piping with a rectangular section and two inlets (16), that are connected to the smoke-exhaust windows of the melting furnace, and by an exit (17) that it is connected through the rectangular opening (14), to the smoke-escape pipe which passes inside the modules; stirrups (18) harden the pipe jolt, and the pins (19) support part of its weight, on the floor.

6) Aluminum melting system to produce ingots from foundry, as claim 1 ) characterized by the fact that the direct and continuous discharge of the fused metal occurs in a double, spherical picking basin by means of an interposition between the melting furnace and the waiting basins of a deviating or distribution joint () of the melted metal (47) having a cross-sectional pipe (49), supplied internally with heating plates (51 ) to maintain the temperature of the liquid metal to 700°C and the bulkhead to block the flow, and whose ends terminate with two cylindrical mouths (50) having a circular base and then enter into the inlet mouth of the spherical, waiting basins. 7) Aluminum melting system to produce ingots from foundry, as claim 1 ) characterized by the fact that the static melting furnace (13) is equipped, on each of both back-to-back sides, with two smoke exhaust windows (26) and in the center of an opening, inlet (24) of the scrap iron to melt, raised on the work plan by means of a freight elevator (27) and placed in the furnace by means of screw conveyors (25); on the other side of the furnace there are exhaust doors (28) of slags which pass through the grid (29) in order to route them into the screws for selection and retrieval; on the other side, the furnace is equipped with an inlet for the burner flame, and at the bottom of an exit port (30) for the molten metal with the bottom in tilted refractory in order to favor the break-out of the molten metal.

8) Aluminum melting system to produce ingots from foundry, as claim 1 ) characterized by the fact that the rotary furnace is equipped on its extremity of two parallelepipedal bodies (31 ) and (32) which they integrate respectively: first (31 ), the escape pipe window (33) and the ventilation hood (34), the inlet (35) for the scrap iron to melt, and under the line (36) for recovering slags, and the second body (32), the window for smoke exhaust (37), the inlet (38) of the burner flame, and on the bottom the exit channel of the melted metal; on the top, the two bodies are connected by an additional, parallelepipedal and empty body (39).

9) Aluminum melting system to produce ingots from foundry, as claim 1 ) characterized by the fact that the waiting spherical basins are directly based on the ground plan, and placed in correspondence of modules (1 11, 1 1 m, 1 1 n) on both sides, on a supporting platform, which also allows the spinning of the spherical waiting basin, made up by a chassis (42) with a square base of metallic beams to which metallic, vertical supports are connected (43) equipped with wheels (45), conveniently hardened and reinforced with the interpositioning of metallic joists (44), that hold up the spinning supports or the tilting of the spheres. 10) Aluminum melting system to produce ingots from foundry, as claim 1) characterized by the fact that the system is completed by the decks (52) which allow to form new raised work plans, P4 and P5, in correspondence of the melting furnace and of the waiting spherical basins, which are linked to the work plans P2 and P3, by increasing their surface; the additional decks (55) equipped with ladders (56) serve to reach the work plan P1 to which jngot molds, developing on two sides (57), reach the waiting, spherical basins through an end.