DEVICE FOR POSITIONING AT LEAST ONE ELECTRODE FOR SMELTING FURNACES

Abstract

A device for positioning at least one electrode for smelting furnaces includes a container made of metal structural work lined with refractory material (crucible) and a water-cooled structure and by a lid or roof with which vertical electrodes are associated, each one being slideably associated with temporary locking elements, such as a column locking clamp. The device is arranged to the side of a smelting furnace and below a parking position of the electrodes in the periods of interruption of operation of the smelting furnace. The device is constituted by a fixed base with which at least one lifting element, which can slide vertically with respect to the fixed base and is provided with elements that are adapted to determine its position in terms of height and is provided with a load cell, is associated in an upper region.

Claims

1. A device for positioning at least one electrode, usable in electric smelting furnaces that are constituted by a container made of metal structural work lined with refractory material (crucible) and a water-cooled structure and by a lid or roof with which vertical electrodes are associated, each one being slideably associated with temporary locking elements, such as a column locking clamp, the device being arranged to a side of a smelting furnace and below a parking position of said electrodes in the periods of interruption of operation of said smelting furnace, wherein the device comprises a fixed base with which at least one lifting means, which slides vertically with respect to said fixed base and is provided with means that are adapted to determine its position in terms of height and is provided with a load cell, is associated in an upper region, said device determining a position and a weight of each one of said electrodes individually and independently of the others, said device being adapted to temporarily support and to vary the position in terms of height of each one of said electrodes individually and independently.

2. The device according to claim 1, wherein each one of said lifting means is constituted by a head that moves vertically and independently of the others by interacting with actuators, such as a hydraulic fluid actuator provided with hydraulic cylinders, which are adapted to move each one of said heads by way of rods protruding from an upper plate, each one of said hydraulic fluid actuators comprising a tank for containing the hydraulic fluid, said hydraulic cylinders resting on a container for an electric motor that actuates an adapted hydraulic pump, each one of said heads being integral with the respective said lifting means that rests on the respective said rods of said cylinders.

3. The device according to claim 2, wherein each one of said containers rests on said base and is provided with said load cell, each load cell being adapted to determine the weight of the respective electrode independently of the other load cells in the step in which the corresponding said lifting means places said head on said electrode after the release of said column locking clamp.

4. The device according to claim 2, wherein each one of said lifting means includes means adapted to determine the position of the respective said electrode independently of the other lifting means, each one of said lifting means being constituted by switches or stroke limiters, probes/cams of the stroke limiters, and linear position transducers that interact with said rods.

5. The device according to claim 2, wherein in an inactive condition said lifting means is completely retracted, while in an active conditions said lifting means is lifted until said head is placed in contact with the lower end of one of said electrodes, controlling its actual height and constituting a resting element for the subsequent exact repositioning to size.

6. The device according to claim 2, wherein in active conditions for said lifting means said electrode resting on said head is subsequently released by said locking element and said lifting means is subsequently activated and causes said electrode to descend, following it until it is arranged at a desired and preset height, said lifting means also performing simultaneously, by way of said load cells, a weighing of said electrode for consumption control.

7. The device according to claim 6, wherein in active conditions for said lifting means, once said preset height has been reached, said electrode is locked by said locking element, and said lifting means subsequently descends, releasing said electrode for its subsequent insertion into said smelting furnace.

8. The device according to claim 1, wherein each individual lifting means slides, independently of the others, vertically with respect to said fixed base so that a consumed electrode interacting thereon is repositioned at the desired height while the remaining lifting means of the remaining electrodes remains positioned in the inactive condition.

9. The device according to claim 1, wherein said vertical electrodes are retained and moved along the vertical axis by a column locking clamp arranged above said lid or roof and associated with the end of a column supporting arm that protrudes above said lid or roof, said column locking clamp temporarily locking and firmly retaining said electrodes, wherein in the periods of interruption of operation of said smelting furnace, said electrodes are positioned to the side of said container, made of metal structural work lined internally with refractory material, which constitutes said smelting furnace.

10. The device according to claim 1, wherein said base is fixed to the floor, at the position in which said lid or roof of said smelting furnace provided with said electrodes is parked in the periods of interruption of operation, by way of a complementary plate embedded in the concrete and provided with adapted screws that cooperate with adapted locking nuts, both said base and said lifting means being constituted by steel structures provided with adapted cooling systems, wherein the adapted cooling systems include adapted connections that are accessible externally to each one of said lifting means.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0063] Further characteristics and advantages of the disclosure will become better apparent from the detailed description of a particular, but not exclusive, embodiment of the disclosure, which is illustrated by way of non-limiting example in the accompanying drawings wherein:

[0064] FIG. 1 is a view from above of a furnace with the roof open according to the disclosure;

[0065] FIG. 2 is a side view of the furnace with the roof open and the electrodes, extracted, positioned each above a positioning device;

[0066] FIG. 3 is a side view of the device in the non-elongated condition;

[0067] FIG. 4 is a side view of the device in the elongated condition;

[0068] FIG. 5 is a partially cross-sectional view of the device; and

[0069] FIGS. 6, 7, and 8 are views, similar to those in FIG. 2, showing the condition in which the device is elongated up to the height of the respective electrode, the condition in which the device has rebalanced the height of the electrodes following the loosening of the arm vise, and the subsequent condition in which, with the arm vise clamped shut, the device is lowered.

DETAILED DESCRIPTION OF THE DRAWINGS

[0070] In the embodiments illustrated below, individual characteristics shown in relation to specific examples may in reality be interchanged with other, different characteristics, existing in other embodiments.

[0071] With reference to the figures, the reference numeral 1 designates a device for positioning at least one vertical electrode 2, advantageously of the column type and used in electric smelting furnaces 3 that are constituted by a container 4 made of metal structural work lined with refractory material (crucible) and a water-cooled structure and by a lid or roof 5 which further makes it possible to obtain different inclinations according to the operation that is to be carried out, such as pouring and slagging operations.

[0072] In the specific embodiment shown by way of example, the lid or roof 5, which rotates, is provided with one to three holes through which pass the vertical electrodes 2, preferably made of graphite, which penetrate into the crucible and are arranged, for a three-phase power supply, according to the vertices of an equilateral triangle.

[0073] It should be noted that the roofs do not always open and rotate with the electrodes (or are associated with them); in some furnaces the lid remains on the furnace and only the electrode assembly rotates to park or onto another adjacent furnace arranged in a twin shell arrangement (the same set of electrodes smelts on one furnace while the other is being loaded and thus in alternation); the device also applies to such types.

[0074] The vertical electrodes 2 are held and moved according to the vertical axis by locking elements 6 such as a conventional column locking clamp, arranged above the lid or roof 5 and associated with the end of a column supporting arm 7 protruding above the lid or roof 5 proper, said column locking clamp locking and firmly retaining the electrode column positioned inside the crucible, transferring the electricity, by way of a conductive element (shoe) to the electrode column, and inducing movements to adjust the electrode column.

[0075] The device 1 is arranged to the side of the smelting furnace 3 below the parking position of the vertical electrodes 2 in the periods of interruption of operation of the electric smelting furnace 3, as shown in FIGS. 1, 2, 6, 7 and 8, and it is constituted by a fixed base 8 with which at least one lifting means 9, which can slide vertically on the latter, is associated in an upper region.

[0076] In the specific embodiment shown by way of example, the base 8 is fixed to the floor, at the position in which the lid or roof 5 of the smelting furnace 3 equipped with the electrodes 2 is parked in the periods of interruption of operation, by means for example of a complementary plate embedded in the concrete and provided with adapted screws that cooperate with adapted locking nuts.

[0077] Three lifting means 9 are associated with the fixed base 8 in an upper region, are structurally identical and can slide vertically with respect to the fixed base 8 independently of each other.

[0078] Each lifting means 9 is constituted by a head 10 that can move vertically and independently of the others by virtue of its interaction with adapted actuators, for example of the hydraulic fluid type or other type.

[0079] In the particular embodiment, each hydraulic fluid actuator is provided with hydraulic cylinders 11 which are adapted to move the corresponding head 10 by way of adapted rods 12 protruding from an upper plate 13; a tank 14 is provided for containing the hydraulic fluid while the hydraulic cylinders 11 rest on a container 15 for an electric motor 16 that actuates an adapted hydraulic pump 17.

[0080] Each head 10 is integral with the respective lifting means 9 that rests against the rods 12 of the cylinders 11.

[0081] Each container 15 rests on the base 8 and is provided thereat with a load cell 18 that is adapted to determine the weight of each electrode 2 in the step in which the lifting means 9 rests the head 10 on the electrode 2 after the release of the column locking clamp, as illustrated in FIG. 6.

[0082] In each lifting means 9 there are also means adapted to determine the position of the respective electrode 2 independently of the other lifting means 9, said means being constituted by adapted switches or stroke limiters 19, probe/cams of the stroke limiters 20, and linear position transducers 21 that interact with the rods 12.

[0083] Both the base 8 and the lifting means 9 are constituted preferably by steel structures provided optionally with adapted cooling systems, which comprise adapted connections 22a, 22b that are accessible externally to each one of the lifting means 9.

[0084] Each individual lifting means 9 slides, independently of the others, vertically with respect to the fixed base 8 so that the consumed electrode 2 interacting thereon is repositioned at the desired height while the remaining lifting means 9 of the remaining electrodes 2 can remain positioned in the inactive condition.

[0085] In the inactive condition the lifting means 9 is completely retracted, as shown in FIG. 2; in active conditions it is lifted, as shown in FIG. 6, until the head 10 is placed in contact with the lower end 23 of the respective electrode 2, controlling its actual height and constituting a resting element for the subsequent exact repositioning to size.

[0086] In the specific embodiment shown by way of example, the electrode 2 resting on the head 7 is subsequently released by the locking element 6 associated with the lid or roof 5, and the lifting means 9 is activated and causes the electrode 2 to descend, following it until it is arranged at a desired and preset height, as shown in FIG. 7.

[0087] The lifting means 9 also simultaneously performs, by way of load cells, the weighing of the electrode for consumption control.

[0088] Once such preset height is reached, the electrode 2 is locked by the locking element 6.

[0089] The lifting means 9 at this point is made to descend, releasing the electrode 2 for its subsequent insertion into the furnace, as shown in FIG. 8.

[0090] Advantageously, there is a separate control panel which is fixed in a suitable position away from the positioning device 1 and which enables an operator to activate/deactivate one or more lifting means 9.

[0091] The actuations are automatic and manual, controlled with buttons and they do not require manual intervention by the operator on the moving parts, since the operating area of the device 1 and the vicinities are off-limits to operators as they are exposed to very great radiating heat when the lid or roof 5 with the electrodes 2 is in a parking position outside the furnace 3.

[0092] Such areas are in fact usually segregated with enclosures.

[0093] In its operation the device 1 makes it possible to compensate the different wear of electrodes, balancing their length in such a manner that the portion of electrode passed through by the current is the same in all three electrode columns and the system is more balanced, thus improving the electrical and thermal efficiency.

[0094] The condition is further avoided whereby the electrode is too short and the column supporting arm does not have enough travel to keep the face of the electrode at the optimal distance (with the risk that the distance from the scrap metal/melt is too great for the arc to be generated).

[0095] As the electrodes 2 are worn away and are repositioned in terms of height, new electrodes 2 are added to the initial column, a procedure usually carried out manually or by way of robots, by way of a simple and rapid stacking one above the other, using nipple joints.

[0096] The device 1 makes it possible to achieve the following advantage: the portion of electrode passed through by the current will be the same in all three electrode columns and the system will thus be more balanced, thus improving the electrical and thermal efficiency.

[0097] There is also the advantage that the electrode columns will never be too short.

[0098] Thus it has been found that the disclosure fully achieves the intended advantages by providing a device that makes it possible to perform, rapidly and easily, the consumption control of each individual electrode (or even just of the one with anomalous wear) and the subsequent optimization of its position in terms of height, while eliminating the exposure of the operators to risks deriving from conventional operations, and eliminating the risk of breakage of the electrodes, and optimizing the quality of the extension and repositioning, in terms of extent, precision, and frequency of intervention, with consequent reduction of the wear of the desired one or of all (taken individually) the electrodes and of the consumption of electricity, thus optimizing the use of the smelting plant through a better operating efficiency.

[0099] The disclosure thus conceived is susceptible of numerous modifications and variations.

[0100] Naturally the materials used as well as the dimensions of the individual components of the disclosure may be more relevant according to specific requirements.

[0101] The characteristics indicated above as advantageous, convenient or the like, may also be missing or be substituted by equivalent characteristics.