WO2002068724A1 - System for recovering anodes from aluminium smelting baths - Google Patents

Abstract

A system for recovering anodes used in smelting baths for making aluminium comprises: b) a drive unit rotatable about a vertical axis and including an articulated robot arm having gripping means for gripping the anodes, and a tool for breaking the bath block or anode slags and carbon ingots, b) a workstation for successively breaking and removing the bath block and carbon ingots, and c) a conveyor belt assembly for separately unloading the bath and carbon components removed from the anode, and d) an anode taking station for taking up the anodes to be processed and an unloading station for unloading the recovered anode metal constructions.

Description

SYSTEM FOR RECOVERING ANODES FROM ALUMINIUM SMELTING BATHS

Background of the invention

The present invention relates to a system for recovering anodes used in smelting baths for making aluminium, i.e. the anode metal construction and carbon components, and to dispose of the slag or "bath" components.

As is known, in smelting baths for making aluminium, anodes comprising a metal construction or frame and two adjoining ingots made of a carbon powder pressed together with a binding material are conventionally used .

As shown in figure 1, the metal construction or frame of an anode 1 comprises a rod 2 and a supporting element 3 having four X-shape arms 4, and with end portions downward bent in parallel to the rod 2, the supporting element 3 being connected, for example by welding, to the rod 2. At the free end portions of the arms 4, is welded an anchoring plug 5 which can be engaged in cylindrical seats 6 having a size larger than that of the carbon ingots 7. Upon arranging the plugs or pins 5 in the seats 6 of the ingots 7, they are clamped therein by pouring liquid cast iron in the annular gap 8 defined between said plugs 5 and seats 6, and causing the cast iron to solidify to a respective cast iron cup 9.

The thus made anode 1 is then used in per se known aluminium making baths, in which, on a side, the carbon ingots 7 are abraded and, on the other side, bath slags deposit on the top face of the ingots 7 and the bath slag supporting element 3, to form a firmly clamped block 10.

Figure 3 shows an used anode, with corroded carbon ingots 7 and slag block 10, i.e. the so-called "bath". In operation, the corrosion or consume of the ingots 7 and formation of the bath 10 can change from anode to anode depending on several operating parameters, such as the use type, the condition of the bath and so on. With respect to the size, each carbon ingot has conventionally sides of 800 x 600 mm and a height of about 500-600 mm, the overall weight of an anode being of about 12 quintals, whereas the weight of the deposit formed by the bath can amount to several quintals; such size and weights are accordingly comparatively high. At present the bath and ingots are detached in a merely empiric manner and, more specifically, by abutting the vertically arranged anodes against a wall and trying to break the bath and carbon ingots by impacting them by lifting carriage forks. Thus, in addition to a comparatively long time, the mentioned system causes a random breaking of the bath and carbon ingot parts, thereby the carbon broken pieces must be separated in a following step, in which, in order to recover the carbon material, said carbon pieces must be stripped from the remaining bath adhering portions. A full removal both of carbon and bath parts is manually carried out by picks, hammers, chisels and the like. The cast iron cups 9 adhering to the plugs are then removed and fresh plugs 5 are welded to the end portions of the X-shape arms 4 of the supporting element 3. The metal construction 2, 3, recovered and completed as disclosed, is then introduced into two fresh ingots and locked to the latter by the above disclosed cast iron pouring operation.

It would be desirable to remove from the worn anodes, and in a separated manner, the parts or components of the bath 10 and carbon 7 in a manner as complete as possible.

Summary of the invention

Accordingly, the aim of the present invention is to provide a system for recovering anodes used in smelting baths for making aluminium, which system allows to efficiently and fully remove both the bath and carbon ingots, in a accurate, quick and efficient manner, to provide an efficient removal of the bath and carbon components, and with a removal as complete as possible of the bath component from the top surface of the ingots.

According to one aspect of the present invention, the above mentioned aim is achieved by a system having the features of claim 1.

Further improvements of the invention are disclosed in the dependent claims.

The invention provides a lot of important advantages. In particular, the breaking and crushing operations for breaking and crushing the bath and carbon components are performed by specifically designed tools, and with the required crushing force, under a direct control of the operator and in a short time. The bath removal operation can be carried out to a substantial cleaning even of the top surface of the ingots, thereby facilitating the following operation or step for recovering the carbon component, which recovering step will be successively performed in another working room, thereby increasing the separating efficiency. Moreover, it is possible to easily handle the heavy anodes through the anode taking, working and unloading stations, thereby said stations can be made on a small surface, which can be advantageously covered or arranged inside a shed. Moreover, the operator will work from a cabin-like rotatable easy position, and, accordingly, in a protected environment, away from the removal station, in which are successively performed the steps of breaking and removing at first the bath component and then the carbon component, thereby allowing to independently unload said components into dedicated vessels or directly on unloading trucks. The breaking tools are either directly mounted on the articulated arm supported by the operating cabin or in the separating or removal station, thereby said tools can be driven by high power drive systems, of an oleo-dynamic controlled type which can be easily controlled by the operator. The separated component unloading system, in particular, comprises only two conveyor belts, thereby greatly to reducing the system cost.

Claim 2 discloses an advantageous embodiment of the workstation of the system, allowing to quickly serve the three operating stations provided according to the invention.

Claim 3 discloses an advantageous embodiment of the anode gripping means which are directly supported in the articulated arm of the working or operating place.

Claim 4 discloses an advantageous embodiment of the bath and carbon breaking and removing tool.

Claim 5 discloses an advantageous embodiment of the processing station, said processing station including therein the tool for removing the carbon component in the plug or cast iron cup region.

Claim 6 discloses an advantageous embodiment of an unloading belt assembly for unloading the bath and carbon components.

Claim 7 discloses the provision of conveyor belts made as a covered assembly, in order to prevent any powder from being diffused through the working environment.

Claim 8 discloses the possibility of directly recovering, in the loading station, the granular and powder bath component which is conventionally separated in handling the anodes.

Claim 9 discloses an advantageous arrangement of the clamping gripper for gripping the anodes and of the chisel breaking tool arranged on the articulated arm. Claim 10 discloses an advantageous embodiment for providing an optimum cleaning and removing of the bath component from the top face of the carbon ingots. Brief description of the drawings

Further characteristics, advantages and details of the system according to the invention will become more apparent hereinafter from the following disclosure of a system according to the invention which is schematically illustrated, by way of an indicative example, in the accompanying drawings in which are represented several figures, drawn on different scales, and where:

Figure 1 is a perspective view of a prior anode for aluminium making baths;

Figure 2 shows a cross-sectional detail of a carbon ingot in a region thereof receiving an anchoring or clamping plug or pin between the anode metal construction and carbon ingot;

Figure 3 is a cross-sectional view of a worn anode, to be fully recovered;

Figure 4 is a top plan view of the overall system for recovering anodes;

Figure 5 is an elevation view, taken in the direction of the arrow A in figure 4, and clearly shows the anode taking station and workstation, with the cup tool for removing carbon at the plug or anchoring cup regions;

Figure 6 is an elevation view of the workstation, at the end of the bath removal;

Figure 7 is a further elevation view taken according the arrow B of figure 4;

Figure 8 shows the arrangement of the conveyor belts for conveying the detached bath and carbon components according to the invention;

Figure 9 is a detail cross-sectional view showing a cup tool for removing carbon;

Figure 10 is a further detail view showing the chisel tool for removing the bath and carbon components; and Figure 11 shows the arrangement of the clamping or gripping device on the articulated arm, with a clamping surface which is slightly slanted with respect to the longitudinal axis of the articulated arm.

Description of the preferred embodiments

As disclosed in the introductory part of the disclosure, prior electrodes 1 for making aluminium have a metal construction

2, 3 for supporting two opposite carbon half-ingots 7, which respectively comprise two cylindrical seats 6 for engaging therein the plugs 5 of the arms 4 of the X-shape supporting element 3 and, more specifically, with the formation of an annular chamber 8. Upon engaging the plugs 5 in the cylindrical seats 6, said plugs 5 and carbon half-ingots 7 are clamped by pouring into said annular chambers 8 a molten cast iron material which, upon solidifying, will form anchoring or clamping cups 9.

After having used, as desired, the smelting baths for making aluminium, the carbon ingots 7 of the electrodes 1 will be unevenly worn or consumed, with a slag block 9 firmly adhering to the top face of the carbon half-ingots 7 and to the X-shape supporting element 3, as shown by way of an example in figure 3.

The worn or used anodes, in particular, are so recovered as to reuse the metal construction 2, 3 for forming fresh anodes, i.e. for clamping it in fresh carbon ingots 7, as well as for the reusing the carbon component which can be derived from the half-ingots as consumed and detached from the supporting element

3, or from the cups 10, upon removing from their top surface that portion of the bath which firmly adheres to said ingots. Thus, the bath blocks 10, removed from the electrode, will represent a waste or scrap component to be disposed of in any known manner.

In particular, the from the X-shape supporting element 3, the plugs 5 and associated cups 9 are detached and on the arms 4 fresh plugs are welded, before applying the metal construction 2, 3 on two fresh half-ingots 7 for providing a fresh anode 1.

According to the invention, the handling of the anodes and breaking and detaching of the bath and residue carbon half- ingots, as well as the unloading of said bath and carbon components, is performed through a greatly narrowed area, in a very efficient manner, by using specifically designed tools which can be driven by an operator for carrying out all of the necessary operating steps from a workstation 11 having the configuration of a drive cabin 12 and rotatably arranged about a vertical axis 13 thereof on a bed 14, and supporting an articulated arm 16 including several elements, in the embodiment being shown three elements 17, 18 and 19, articulated to one another and with respect to the cabin 12 and adapted to be driven as a robot arm by oleo-dynamic cylinder/piston units and related pivoting arrangements, as shown in the drawings, of any per se known type, such as excavators or soil diggers and which, accordingly, are not herein disclosed in further details. Likewise, the oleo-dynamic circuit controlling said machines, and the electro-hydraulic circuit of a control unit 21 therefor are not further herein disclosed since they would be apparent to one skilled in the art.

As shown in figure 5, the system according to the present invention comprises a worn or consumed electrode 1 taking station 22, a processing station 23, in which both the bath 9 and residue half-ingots 7 are removed, and a delivery station 24 for delivering the metal constructions 2, 3, 9 therefrom the bath block 10 and carbon half-ingots have been removed, and a conveyor belt assembly 26 for unloading the bath component 10 and carbon component 7. More specifically, said electrode taking station 22 comprises, according to a preferred embodiment thereof, a hopper 27 having a grid-like bottom 28 to allow the bath and alumina pieces to freely fall therethrough, which pieces are detached from the block 9 in handling and abutting the anode 1. The number 29 indicates an unloading conveyor belt for unloading said bath fraction separating in the hopper 27. The unloading station 24 is provided for depositing therein the anode metal constructions 2, 3, 9, and said station can also be merely formed by a vessel or a truck for conveying the mentioned metal constructions to a processing shop for removing the plugs 5 and cast iron cup 9 and for welding on the arms 4 fresh plugs 5.

According to the invention, the anodes 1 are handled by a clamping or gripper device 31 provided on the end or front portion 19 of the articulated arm 16. Advantageously, said clamping or gripping device comprises an abutment fixed jaw 32 and a locking movable jaw 33 which can be driven on a slide-like portion coupled to the piston rod 34 of the cylinder-piston unit 36 built-in in said front arm portion 19.

According to the invention, and as shown in the drawings, to said piston rod 34 is moreover coupled a chisel tool 37 for breaking the slag block or bath 10 and carbon ingots 7 of the anode 1. To perform this, the rod 2 of the anode 1, in the loading station 22, is at first locked in the clamping device 31 of the arm 19 slightly above the bath block 10; then said rod 2 is turned from a vertical position thereof to a horizontal position thereof in which its free end portion is directed towards the processing or workstation 23, in an anti- clockwise direction.

The workstation 23 comprises a further clamping device 38 including a fixed abutment jaw 39 and a locking movable jaw 41 mounted on the free end portion of the piston rod 42 of an oleo-dynamic cylinder/piston unit 43 coupled to the framework 44 of said workstation 23.

Since the efforts exerted on the bath block 10 and carbon half-ingots 7 must be of a comparatively high value, the locking of the anode 1 in the workstation 23 is not performed by clamping the rod 2, but by operating on the X-shape supporting element 3, the opposite sides of the jaws 39 and 42 being so contoured as to mate with the corresponding curved portions of the arms 4, thereby providing a firm locking of a geometrical engagement type.

According to the invention, the bath block 10 is removed by means of the chisel tool 37 which, since it is provided for scrape away the bath layer adhering to the half-ingots 7, will advantageously have a spatule configuration. Moreover, on the side 37 thereof opposite to the half-ingots 7, the chisel tool 37 has a T- shape rib 46 having cutting edges 46A to improve the breaking of the block 10 and the removal of the broken away portions to the outside, i.e. outside the "cage" formed by the arms 4. The pivot connections of the arm 16 will allow the chisel tool 37 to impact against the bath block 10 at any regions thereof, thereby likewise scraping the top side of the half-ingots 7 through the overall surface thereof, also inside said arms 4, as is shown in the figures. The bath pieces 10 being successively detached will fall, under gravity, on the underlying first conveyor belt 47, the other end portion 48 thereof discharges the pieces on a second conveyor belt 49, which is substantially cross-arranged with respect to the first conveyor belt 48 and which can be bidirectionally driven, as shown by the arrow 51. As shown, the two end portions 52 and 53 of the second conveyor belt 49 respectively discharge the pieces into a vessel or truck 54, for example for collecting the bath component, and into a further vessel or truck 55, for collecting the carbon component. At the end of the removal of the bath 10 and after having discharged the bath component into its respective vessel or truck, for example 54, it is possible to immediately start the carbon half-ingot removal or breaking operation and this, according to the invention, in that same workstation 23, and without the need of displacing the anode 1.

According to the invention, the removal of the carbon half-ingots 7 is performed at first by further using the chisel tool 37 for the portions of the ingots from away to comparatively near the cast iron cups 9, and by using the four cup breaking tools 57 which can be reciprocatedly driven coaxially to the axes of the four anchoring or clamping plugs 5 of the X-shape supporting element 3, and being respectively coupled to the free end portion of a piston rod 58 of an oleo-dynamic cylinder/piston unit 59 fixed to the framework 44 of the workstation 23. More specifically, each tool 57 comprises a bottom plate 61 including a plurality of breaking tips 62 which are circumferentially distributed and clamped to said plate 61, for example welded thereto. The number of said breaking tips or points can be freely chosen: practically, very good results have been achieved by providing five tips or breaking points. Since, during the feeding and breaking displacement inside said cup tools 57 the removed carbon portion 7 remain trapped therein, which would hinder an efficient subsequent use of the tools 57, according to the present invention, to the workstation 23 construction 44 are coupled, for each tool 57 for example two pins 63 which, as the tools 57 are withdrawn, will engage in two holes 64 of the bottom plate 61, thereby, in the last portion of the back-stroke of the tools 57, said pins 63 will eject the carbon pieces 7 inside the tools 57, thereby fully freeing said inside for a following use. The carbon pieces 7, detached from the anode 1 and forming the carbon component, will likewise fall under gravity on the underlying conveyor belt 47 which will discharge said carbon component on the second conveyor belt 49 so driven as to cause the carbon component 7 to fall into the dedicated vessel or truck 56. Thus, according to the invention, by providing only two conveyor belts, it is possible to independently and separately discharge both the slag component or bath 10 and the carbon component 7.

After having removed the carbon component, the metal construction 2, 3, 9 of the anode will be brought to the unloading station 24, as above shown.

In order to assure a cleaning as complete as possible of the top side of the half-ingots 7 adjoining the bath, and in view of the thickness of the arm front portion 19, according to a feature of the invention, the clamping surface of the clamping device 31, instead of being perpendicular to the longitudinal axis of the arm front portion 19, will be slightly slanted thereto.

Moreover, for preventing noxious powder from being diffused through the work environment, for example in a shed, the two conveyor belts 47 and 49 are provided with a covered arrangement.

From the above constructional and operating disclosure, it should be apparent that the system according to the present invention efficiently achieves the indicated aim and the mentioned advantages. In particular, the operations or steps for breaking the bath block 10 and the two carbon half-ingots 7 can be performed in a rational, reliable, quick and complete manner, so as to provide an anode metal construction ready for removing therefrom the cast iron cups 9 and welding thereto fresh plugs 5 for forming a fresh or novel anode. Moreover, the carbon pieces adjoining the bath 10 are substantially free of slags and comprise only a thin slag layer, thereby facilitating the following separating step for recovering the carbon component.

In practicing the invention, one skilled in the art can perform modifications or variations, such as, for example, that of providing two independent unloading belts for independently unloading the two bath and carbon components, or a provision of breaking tools having a different configuration, and so on, without departing from the scope of the invention.

Claims

1. A system for recovering anodes used in smelting baths for making aluminium, characterized in that said system comprises: a) a drive station rotatable about a vertical axis thereof and including an articulated robot arm having gripping means for gripping a single anode, and a breaking tool for breaking a bath block and carbon ingots, b) a workstation, for breaking and removing the anode both from said bath block and from the residue carbon ingots, c) a conveyor belt assembly for separately unloading the bath and carbon components removed from the anode, and d) an anode taking station for taking up the anodes to be recovered and an unloading station for unloading the recovered metal constructions.

2. A system according to Claim 1, characterized in that said drive station is designed as a drive or control cabin for an operator, and that the articulated movable portions of the robot arm are driven by oleo-dynamic elements interconnected in a hydraulic circuit having a dedicated electro-hydraulic center unit.

3. A system according to Claim 1, characterized in that said gripping means on said articulated arm comprise a clamping device for clamping an anode, said clamping device preferably including a fixed abutment jaw and a movable locking jaw.

4. An system according to Claim 1, characterized in that said tool on said articulated arm comprises a chisel tool, said chisel tool, in an inner region thereof, including preferably a T- shape rib adapted to operate as an additional cutting and abutment element for removing the detached bath and carbon pieces.

5. A system according to Claim 1, characterized in that said workstation comprises, on a supporting framework: a) a clamping device for clamping and locking the anode, having a fixed abutment jaw and a movable locking jaw, said jaws engaging on a X-shape supporting element of the anodes, being suitably contoured and engaging with a geometrical type of engagement with said X-shape supporting element, and b) four breaking tools for breaking said carbon ingots near said cast iron cups, said breaking tools being reciprocatedly driven coaxially with respect to the axes of four clamping plugs of said X- shape supporting element, being coupled to driving means and having a cup configuration defined by a bottom plate including a plurality of circumferentially arranged breaking tips coupled to said bottom plate, said driving means comprising oleo-dynamic cylinder/piston units fixedly mounted on said framework of said workstation.

6. A system according to Claim 1, characterized in that said unloading belt assembly for unloading said bath and carbon components comprises a first shared conveyor belt coupling the bottom of the workstation to a second conveyor belt arranged substantially transversely of said first conveyor belt, being located under a free end portion of said first conveyor belt and being adapted to be bidirectionally driven, thereby discharging, from one end portion thereof, into a first vessel or truck receiving a first component, for example the bath component and, from the other end portion thereof, into a second vessel or truck, receiving the other component, for example the carbon component, and where on said first conveyor belt are alternately and separately discharged the bath component and carbon component of each anode.

7. A system according to Claim 6, characterized in that said first and second conveyor belts have a protected-covered arrangement.

8. A system according to Claim 1, characterized in that in said anode taking station is provided an anode hopper having a grid bottom, and, under said anode hopper being arranged a collecting vessel or conveyor belt for discharging the fallen bath and alumina portions.

9. A system according to Claim 1, characterized in that said articulated arm comprises a front arm portion supporting a cylinder/piston unit driving both said movable jaw of said anode clamping device and said reciprocating movement on a slide guide of said breaking tool.

10. A system according to Claim 1, characterized in that said clamping device provided on said articulated arm front portion comprises a clamping surface defining, with a longitudinal axis of said articulated arm front portion, on a side of one end of said articulated arm front portion, an angle slightly greater than 90°.

11. A system according to one or more of the preceding claims, characterized in that said anode taking, anode processing and anode metal construction unloading stations are substantially arranged on a same circumference.