IT202000005281A1 - FEEDING EQUIPMENT TO FEED BALES OF ZINC SCRAP TO A MELTING TANK - Google Patents

Description

DESCRIPTION

attached to a patent application for industrial invention entitled:

FEEDING EQUIPMENT TO FEED BALES OF ZINC SCRAP TO A MELTING TANK

DESCRIPTION

The present invention relates to a feeding apparatus for feeding zinc scrap bales to a melting tank.

How ? known in the sector, in recycling plants the zinc scrap destined for recovery is first of all pressed to form bales which make it easier to transport. easy, both thanks to its regular shape, and thanks to the fact that the scraps are pressed into them and therefore the empty space? reduced. The bales, whose unit weight? about 1000/1200 kg, are then sent to the actual recovery plants, which melt them, eliminate most of the slag and produce ingots ready for a subsequent new melting for reuse.

The melting of zinc bales takes place inside heated tanks in which, when fully operational,? a bath of molten zinc is constantly present, which is gradually withdrawn at an outlet, and sent to the ingot mold.

In accordance with the technology currently used, in the center of the melting tank? positioned an open box at the top and bottom and which defines a vertical insertion duct for the bales. To the caisson? then associated with a suction hood designed to remove the fumes that develop as the bales melt, and what? equipped with front opening doors. The bales are stacked one on top of the other inside the box and descend towards the bathroom as soon as those more? at the bottom they melt.

The loading technology currently used involves the use of a? Spider? mounted on a mechanical arm in turn mounted on a vehicle. In order to proceed with the loading,? therefore, first of all, it is necessary to open the front doors of the hood, and to place a new bale on top of the pile. Normally the feeding is done in two bales at a time, after which the doors are closed again until the next load.

This mode? to proceed, however, entails numerous drawbacks. These discontinuous insertions, with open doors, in fact involve very large peaks of emissions in the working environment of volatile organic compounds (VOCs). There? ? due to the need? to work with open doors which, on the one hand, facilitates itself? the escape of fumes and, on the other hand, nullifies, during the loading time, the action of the suction hood.

Further, it should be noted that the pi? large quantities? of VOCs are formed just when the new bales are loaded. The weight of these unloaded on the underlying, combined with the energetic action of pushing downwards exerted by the mechanical arm (necessary to release the previously placed bales which tend to merge at the level of the bathroom and form a single body with the body), in fact, determines a sudden sinking of the entire pile in the melt bath and an equally sudden volatilization of many impurities? present in the scrap which at that moment comes into contact with the melting bath for the first time (at a temperature of about 450 ° C).

Last but not least, the melting plants used today have poor efficiency and involve very high energy consumption.

In this context, the technical task underlying the present invention? realizing a feeding apparatus for feeding zinc scrap bales to a melting tank, which remedies the aforementioned drawbacks.

? in particular, the technical task of the present invention is to provide a feeding apparatus for feeding bales of zinc scrap to a melting tank, which allows to drastically reduce both the risk of VOC release in the working environment and the formation of VOC peaks from manage with the suction system, compared to the solutions known today.

? further technical task of the present invention is to provide a feeding apparatus for feeding bales of zinc scrap to a melting tank, which allows a smaller feeding of the bales. continuous and uniform with respect to known apparatuses.

Not last, ? technical task of the present invention to provide a feeding apparatus for feeding zinc scrap bales to a melting tank, which involves lower energy consumption than known apparatuses.

The technical task and the aims indicated are substantially achieved by a feeding apparatus for feeding bales of zinc scrap to a melting tank, in accordance with what is described in the appended claims.

Further characteristics and advantages of the present invention will become more evident from the detailed description of some preferred, but not exclusive, embodiments of a feeding apparatus for feeding bales of zinc scrap to a melting tank illustrated in the accompanying drawings, in which:

Figure 1 in plan view of an apparatus made in accordance with the present invention, associated with a melting tank;

Figure 2 shows a front view of the apparatus of Figure 1 (seen from the right with respect to Figure 1);

Figure 3 shows a side view of the apparatus of Figure 1 (seen from below with respect to Figure 1);

- figure 4 shows the apparatus of figure 2, sectioned along the line IV-IV;

Figure 5 shows the apparatus of Figure 3, sectioned along the line V-V;

figure 6 shows the apparatus of figure 4 in a different operating condition;

Figure 7 shows the apparatus of Figure 5 in a different operating condition;

Figure 8 shows the apparatus of Figure 2 in a different operating condition;

- figure 9 shows the apparatus of figure 8, sectioned along the line IX-IX; And

- figure 10 shows a variant embodiment of the apparatus object of the present invention, illustrated with reference to a layout otherwise similar to that visible in figure 5.

With reference to the figures cited? The reference number 1 globally indicates a feeding apparatus for feeding bales 2 of zinc scrap to a melting tank 3, made in accordance with the present invention.

Those shown in the accompanying figures are a preferred embodiment of the power supply apparatus 1, in which the apparatus itself has the most common configurations. complete. As explained below, however, in other embodiments the apparatus can be also assume different, or less complete, configurations.

It should also be noted that both the feeding apparatus 1 alone, and a melting apparatus 4 for melting bales 2 of zinc scrap, which includes the feeding apparatus 1, fall within the present invention. melting apparatus 4 comprises a melting tank 3 and a heating chamber 5 which surrounds the melting tank 3 at least laterally, but preferably also below. In the heating chamber 5 are installed one or more? burners 6 suitable for generating the heat necessary to heat the melting tank 3, and what is contained therein, sufficiently to cause the zinc to melt. So by itself? known, an evacuation path of the fumes produced by one or more? burners 6, then connects the heating chamber 5 to an external chimney (not shown).

In the preferred embodiment, the feeding apparatus 1? mail in the vicinity? of a first edge 7 of the melting tank 3 opposite to a second edge 8 where, below the operating level,? there is a duct (not shown) for the discharge of the liquid zinc from the melting tank 3 towards the mold. Advantageously, in the case of a melting tank 3 with a rectangular plan, these edges 7, 8 are those which correspond to the short sides of the rectangle.

This location, compared to the central one foreseen in the plants known today, frees an area without obstacles on the surface of the tank for the operations of collecting ashes, scrap of other metals (Fe and Al) and matta (an alloy of Fe at 2/3% and Zn for the rest which, at the working temperature, manifests itself in a semi-liquid form and settles on the bottom of the tank), thus facilitating the execution of these operations which are to be carried out on a weekly basis.

In its embodiment pi? simple, the feeding apparatus 1 object of the present invention comprises a first support structure 9, a hollow containment body 10 and at least one device for controlled movement 11 of the bales 2.

The first support structure 9? advantageously fixed to the ground 17 and acts as a support, both for the hollow containment body 10, and for the device 11 for controlled movement of the bales 2 (Figure 9).

Inside the hollow containment body 10 develops, from top to bottom, a sliding duct 12 which starts at an upper opening 13 of the hollow containment body 10, and ends at a lower opening 14 of the hollow containment body 10. In the preferred embodiments, the sliding duct 12 has a vertical extension.

The upper opening 13 and the lower opening 14 are configured to constitute, respectively, a bale insertion section 2, and a bale release section 2 towards the melting tank 3. Advantageously, the upper opening 13 and the lower opening 14 they are also the only openings that put the inside of the hollow containment body 10 in communication with the external environment that surrounds it. The hollow containment body 10 for the rest? in fact, advantageously such as to prevent the passage of gasses between the inside and the outside.

At the upper opening 13 of the hollow containment body 10? moreover advantageously associated with a suction hood (not shown) which, according to the embodiments, can? be wholly or partially integrated in the power supply device 1, or be independent from it. The lower opening 14? moreover configured to be completely facing, in use, a bath of molten zinc contained in the melting tank 3 located under the feeding apparatus 1. For this purpose, the sliding duct 12? advantageously projected with respect to the first support structure 9.

Furthermore, preferably the hollow containment body 10? configured and sized in such a way that the lower opening 14 is at a higher level? low, with respect to a predetermined operating filling level 15 of the melting tank 3; in this way, in fact, in use, the lower opening 14? immersed in the molten zinc bath contained in the melting tank 3, and there can? be the passage of gasses between the internal part of the hollow containment body 10 and the surrounding environment through the lower opening 14. How? evident, in this case the hollow containment body 10 will have to? be made of a material capable of easily resisting the temperature of the molten zinc bath 16 (of the order of 450 ° C).

The controlled handling device 11 of the bales 2? associated with the sliding duct 12, and? configured to lower each bale 2 in a controlled manner from the upper opening 13 towards the lower opening 14, as well as? to subsequently let each bale 2 exit from the sliding duct 12, through the lower opening 14, so that it can immerse itself in the molten zinc bath 16.

In the preferred embodiment, the controlled movement device 11 comprises a plurality of elements. of retaining members 18 having a predetermined distance from each other, a distance such as to allow the positioning of a bale 2 between each pair of successive retaining members 18 (remember that the bales 2 have a constant width and height? the shapes? while they can have slightly variable lengths depending on the material that is loaded into the press from time to time); in particular, ? it is preferable that the bales 2 are inserted straight into the sliding duct 12 (ie with length and width oriented transversal to the direction of development of the sliding duct 12 and with the height parallel to the direction of development).

Each detention body 18? cyclically mobile along a working path, which develops in the sliding duct 12 along the direction of its development (vertically in the accompanying figures), from an upper position in which the holding member 18 can? be loaded with the relative bale 2, up to a lower position. Each detention body 18? configured to interfere with the volume of the sliding duct 12, to retain a bale 2 resting on it, along the entire working path. Moreover, after reaching the lower position, each retaining member 18 moves further towards a disengagement position in which it frees the sliding duct 12, to let the bale 2 held by it descend beyond the release opening. From the disengagement position, each retaining member 18 then returns to the upper position for a new work cycle.

In the embodiment illustrated (see Figure 9), the controlled movement device 11 comprises two synchronized motorized chains 19, arranged transversely spaced in the sliding duct 12 (spaced parallel to the plane of the sheet in Figure 5), each developing in a ring, between an upper return wheel 20 and a lower return wheel 21 (at least one of which is motorized). In each chain 19? therefore identifiable an operating section 22, located in correspondence with the work path, and a return section 23, parallel to the operating section 22 and placed outside the sliding duct 12. The retaining members 18 each consist of a horizontal shelf fixed to both motorized chains 19 and cantilevered. The retaining members 18 are associated with the motorized chains 19 with constant pitch. Each retaining member 18, as seen in Figure 9, protrudes into the sliding duct 12 sufficiently to create a narrowing such as to prevent the passage of a bale 2 of zinc. Since the detention body 18? positioned laterally with respect to the sliding duct 12, the zinc bale 2, once resting on the retaining member 18, tends to overturn, and instead rests on the hollow containment body 10, substantially obstructing the duct with its width. sliding 12 (parallel to the sheet in figure 9).

Parallel to the development of the brackets, on the other hand, the bales 2 always have a shorter length than the dimension of the sliding duct 12.

Figure 10 shows an embodiment variation of the present invention, in which a portion of the sliding duct 12 forms part of the path for evacuating the fumes produced by one or more? burners 6, so that these hot fumes can preheat the bales 2 present in the sliding duct 12 before they are immersed in the molten zinc bath 16 (preheating up to a temperature of about 380 ° C).

It should be noted that the constant and gradual introduction of the bales 2, preheated before contact with the molten zinc, cuts the peaks of VOC emissions compared to what happens in the plants used today in which? a step is provided for the direct and discontinuous insertion of the non-preheated zinc bales 2. The preheating thermal treatment with the fumes coming from the heating of the molten zinc treatment tank also ignites the emissions of organic compounds that are released by pyrolysis, at a certain temperature, from the impurities. present in the scrap. This phenomenon therefore leads to a direct use also of the energy released by this combustion, as well as? to a corresponding reduction in VOC emissions towards the chimney. Another important reduction occurs with regard to consumption, thanks to the preheating of the zinc bales 2, which can? portal at temperatures of about 380? C, given that the thermal energy necessary to reach this temperature is equivalent to about 50% of the energy necessary to obtain the complete fusion starting from the ambient temperature and to reach about 450? C of the molten zinc in the tub.

In this embodiment, the apparatus further comprises at least a first flue gas evacuation duct 24 which connects the heating chamber 5 to the sliding duct 12 in the vicinity of the of the lower opening 14, and a second flue gas evacuation duct 25 connected between the sliding duct 12, in the vicinity of of the upper opening 13, and the chimney. At least to the second flue gas evacuation pipe 25? connected a suction device 26, but an aspirator can? also be provided in the first flue gas evacuation duct 24. In this configuration, the portion of the sliding duct 12 comprised between the first smoke evacuation duct 24 and the second smoke evacuation duct 25? what constitutes part of the evacuation path of the fumes produced by one or more? burners 6.

A temperature gauge 27, a pressure gauge 28 and a residual oxygen gauge 29 can be associated with the first evacuation duct 24, and with the second evacuation duct 25, as well as with the and a throttle valve 30 that can? allow the entry of ambient air, for example in order to favor a completion of the combustion of any VOCs present in the fumes. The opening of the throttle valve 30? advantageously controlled by a unit? electronics (not shown) also connected to the meters as well as, advantageously, to all the operating parts of the loading equipment 1 and / or of the melting equipment 4.

In its implementation forms the most? complete, the feeding apparatus 1 object of the present invention further comprises a loading device 31, configured to feed the bales 2 to the controlled handling device 11 at the upper opening 13.

Advantageously, the loading device 31 comprises at least a second support structure 32, which can constitute a whole with the first support structure 9 or be independent from it.

Preferably, the second support structure 32 supports a track 33, preferably horizontal, to which? slidingly associated with a motorized carriage 34 equipped with gripping means 35 for holding and handling the bales 2.

The motorized carriage 34 moves along the track 33 between a pick-up position and a release position.

When in the release position (figure 5), the motorized carriage 34? placed in correspondence with the upper opening 13 to feed a bale 2 into the sliding duct 12 and to the controlled handling device 11. When is it instead in the pick-up position? spaced from the upper opening 13, and can? pick up a bale 2 (to be transported to the release position).

In the preferred embodiments, the motorized carriage 34? equipped with lower gripping means 35 (therefore shaped like a sort of bridge crane) which are switchable between an operating position, in which they can hold a bale 2 together, and a rest position, in which they are more than one another. spaced apart than in the operative position, and allow the positioning of a bale 2 between them. The lower gripping means 35 are therefore configured as a gripper, and switching from the operating position, in which they hold a bale 2, to the rest position, causes the bale 2 to fall downwards.

Although it is possible to provide that the bales 2 are supplied directly to the motorized wagon 34, in the preferred embodiments the loading device 31 further comprises a lifting device 36 adapted to move a bale 2, between an area in which the bale 2 can be moved. be positioned, for example, by means of a common forklift, up to the pick-up position of the motorized wagon 34.

In preferred embodiments, the loading device 31 comprises a platform 37, which? mobile between a lowered position (figure 4), in which? distanced from the pick-up position of the motorized carriage 34 and can? receive a bale 2, and a raised position (figure 6), in which? placed in correspondence with the pick-up position of the motorized carriage 34 to allow it to pick up the bale 2 positioned on the platform 37.

In some embodiments, platform 37? supported on the second support structure 32, and moved with respect thereto, by means of a plurality of of flexible elements 38 operated by actuators 39, to which? hanging. As can be seen for example in Figure 4, the platform 37 has a rectangular plan and? hanging, at each corner of the rectangle, from a flexible tie rod 38 which extends upwards to a first return pulley 40; from the first return pulley 40, each tie rod 38 then extends downwards until it hooks onto a piston 41 of an actuator 39. In particular, in the preferred embodiment, the two tie rods 38 associated with the edges located on the same side short of the platform 37 are actually? each consisting of a single flexible element which, in correspondence with the piston 41 of the actuator 39, wraps in part around a second idle return pulley 42 carried by the piston 41 itself and then connects at the top to the second support structure 32 (figures 4 and 6). In this way, in the embodiment illustrated in the accompanying figures, in which the cylinder 43 of the actuator 39? fixed in the vicinity? of the base of the second support structure 32 and extends upwards, when the actuator 39? extended, the platform 37? placed in the lowered position, while when the actuator 39? retracted, platform 37? placed in the raised position.

At the bottom, platform 37? equipped with four feet 44 inclined towards the outside, destined, when the platform 37 is in the lowered position, to rest on respective supports 45, each comprising an idle roller 46. The inclined conformation of the feet 44 allows them to be used as centering means of the platform 37 in the lowered and locking position of the same with respect to the lateral movements. In this position, in fact, the bales 2 are loaded onto the platform 37 and the platform 37 can? be subject to blows that could otherwise cause it to swing, as it is simply hanging.

Finally, in the preferred embodiment, when in the lowered position, the platform 37 is not? close to the ground (a solution that can still be envisaged in other embodiments), but is at a height of at least 2 meters above the ground, but in any case at a height that can be reached by a common forklift used in foundry for handling bales 2 .

The operation of the power supply apparatus 1 illustrated in the accompanying figures? the following.

A bale 2 to be loaded is placed with a forklift on the platform 37 placed in the lowered position, which is then raised to the raised position. At that point the motorized carriage 34 in the pick-up position switches the lower gripping means 35 from the rest position to the operative position to retain the bale 2. The platform 37 then descends towards the lowered position, and the motorized carriage 34 moves up to the release position. Appropriate control systems not described in detail will authorize the actual arrival of the motorized carriage 34 in the release position only when it is not yet occupied by a previously fed bale 2.

In the release position, the motorized carriage 34 possibly continues to hold the bale 2 until a free holding member 18 is in the upper position. At that point, the lower gripping means 35 switch from the operative position to the rest position, and drop the bale 2 onto the holding member 18. How already? seen, the bale 2 will position itself? with a lower edge 7 resting on the retaining member 18 and with an upper edge 7, diametrically opposite, resting on the hollow containment body 10 (Figure 9).

You must also? note that, in correspondence with the pick-up position and / or the release position, the motorized carriage 34 can? assume different positions along the track 33, in order to be able to position the bale 2 in the sliding duct 12 in different axial positions as illustrated for example in Figure 5, in particular in such a way that the bales 2 are alternately resting on a distal face, and to a proximal face, of the hollow containment body 10 (the control of the various positions can be obtained, for example, by means of sensors and / or encoders). This is particularly advantageous if the flow duct 12 is also part of the smoke evacuation path, as it creates a zig-zag path for the fumes which allows to increase the contact area between the bales 2 and the hot fumes, obtaining a better preheating of the bales 2.

At full capacity, the situation will be? then always the one visible, for example in Figure 5, with a bale 2 being dissolved in the molten zinc bath 16, and the others each in correspondence with a holding member 18. The controlled handling device 11 in fact lowers the bales 2 towards the bathroom, moving each retaining member 18 from the upper position to the lower position (understood as the last position in which they are able to retain the respective bale 2). The subsequent advancement of the retaining member 18 causes it to disengage the sliding duct 12, and leaves the bale 2 free to fall downwards. Advantageously, however, the rate of descent of the bales 2? chosen in such a way that at the moment of the fall of a bale 2, the one below is not yet completely melted, so that? a real dip of the bale 2 into the molten zinc bath 16 is avoided, albeit from a very low altitude. Advantageously, the rate of descent of the bales 2? then controlled in such a way as to guarantee, with a certain tolerance, a certain constancy of feeding (in terms of kg / hour). For this purpose, the loading device 31? advantageously equipped with weighing systems for each bale 2 and the handling of all the elements? controlled by the unit? electronics.

It should also be noted that in its embodiment pi? complete, the feeding equipment 1 allows loading operations with the forklift in groups of two / three bales 2. Once a first bale 2 has been positioned on platform 37, in the time necessary to pick up a second bale 2 with the forklift , the platform 37 can? transfer the first bale 2 to the motorized carriage 34 and return to the lowered position. In the time required for the displacement of the platform 37 from the raised position to the lowered position, for the loading of the second bale 2 and for the return of the platform 37 from the lowered position to the raised position, the motorized carriage 34 can? reach the release position, feed the first bale 2 to the unloading duct (if free) and return to the pick-up position. At that point, the motorized wagon 34 can? pick up the second bale 2 and platform 37 can? return again to the lowered position where it can? be loaded with a third bale 2. The loading operations with the forklift can therefore be suspended until the unit? electronics avr? proceeded to feed in succession also the second bale 2 and the third bale 2 to the controlled handling device 11, as well as? until when will it not be? available, or nearly so, a free retaining member 18 at the upper position. At that moment the operations can be repeated and another three bales 2 loaded.

Obviously, ? however it is possible to carry out the operations even one or two bales 2 at a time.

The present invention achieves important advantages.

First, thanks to the present invention? It has been possible to develop a feeding apparatus 1 for feeding bales 2 of zinc scrap to a melting tank 3, which allows to drastically reduce the risk of VOC release in the working environment with respect to the solutions known today.

Secondly, the present invention allows a feeding of the bales 2 more? continuous and uniform with respect to known apparatuses.

Furthermore, the embodiments which provide for the use of the fumes for preheating the material involve significantly lower energy consumption of the melting plant compared to known apparatuses.

Finally, it should be noted that the present invention is relatively easy to produce and that the cost associated with its implementation is also not very high.

The invention so? conceived? susceptible of numerous modifications and variations, all of which are within the scope of the inventive concept that characterizes it.

All the details can be replaced by other technically equivalent ones and the materials used, as well as? the shapes and dimensions of the various components may be any according to requirements.

Claims (11)

CLAIMS 1. Feeding equipment for feeding zinc scrap bales to a melting tank (3), comprising: a first support structure (9); a hollow containment body (10) mounted on the first support structure (9), in which? obtained a sliding duct (12) which extends from top to bottom, from an upper opening (13) to a lower opening (14), where the upper opening (13) and the lower opening (14) are configured to constitute, respectively, a bale insertion section (2) and a bale release section (2), and where the lower opening (14)? moreover configured to be completely facing, in use, a molten zinc bath (16) contained in a melting tank (3); at least one controlled bale handling device (11) (2), associated with the sliding duct (12), and configured to make each bale (2) descend in a controlled manner from the upper opening (13) towards the lower opening (14) ) and to subsequently let each bale (2) exit from the sliding duct (12) through the lower opening (14). Feeding apparatus according to claim 1 wherein the lower opening (14)? configured to be placed at a higher altitude? low with respect to a predetermined operating filling level (15) of the melting tank (3), to be immersed, in use, in a bath of molten zinc (16) contained in the melting tank (3). Feeding apparatus according to claim 1 or 2, wherein the controlled movement device (11) comprises a plurality of materials. of retaining members (18) having a predetermined distance from each other to allow the positioning of a bale (2) between each pair of successive retaining members (18), each retaining member (18) being cyclically movable along a path of work, which develops in the sliding duct (12), from an upper position to a lower position, and being configured to interfere with the sliding duct (12) to hold a bale (2) resting on it along the entire length working path, after having reached the lower position, each retaining member (18) moves towards a disengagement position in which it frees the sliding duct (12) to let the bale (2) held by it go down beyond the release opening . 4. Feeding apparatus according to claim 3, in which the retaining members (18) are associated in cantilever mode, with a constant pitch, to at least one motorized chain movable along the working path. Feeding apparatus according to any one of claims 1 to 4, further comprising a loading device (31), configured to feed the bales (2) to the controlled handling device (11) at the upper opening (13) . Feeding apparatus according to claim 5, wherein the loading device (31) comprises a second support structure (32), a horizontal track (33) supported by the second support structure (32) and a motorized carriage (34 ) slidingly associated with the track (33) to move between a pick-up position, in which? spaced from the upper opening (13) and can pick up a bale (2), and a release position in which? placed in correspondence with the upper opening (13) to feed a bale (2) to the sliding duct (12). Feeding apparatus according to claim 6 wherein the motorized wagon (34)? equipped with lower gripping means (35), which can be switched between an operating position in which they can hold a bale (2) together, and a rest position in which they allow a bale (2) to be positioned between them. Feeding apparatus according to any one of claims 6 to 7, wherein the loading device (31) further comprises a lifting device (36) comprising a platform (37), movable between a lowered position in which? distanced from the pick-up position of the motorized carriage (34) and can? receive a bale (2), and a raised position, in which? placed in correspondence with the pick-up position of the motorized carriage (34) to allow it to pick up the bale (2) positioned on the platform (37). Feeding apparatus according to claim 8 wherein the platform (37)? supported on the second support structure (32), and moved with respect to it, through a plurality of of flexible elements (38) operated by actuators (39) to which? hanging. 10. Melting apparatus for melting bales (2) of zinc scrap, comprising a melting tank (3), a heating chamber (5) which laterally surrounds the melting tank (3), and a feeding apparatus (1) according to any one of claims 1 to 9 arranged with the second opening facing the upper part of the melting tank (3), in which the heating chamber (5) comprises one or more? burners (6), and in which the apparatus further comprises at least a first flue gas evacuation duct (24) which connects the heating chamber (5) to the sliding duct (12) in the vicinity of the burners (6). of the lower opening (14), and a second flue gas evacuation duct (25) connected to the sliding duct (12) in the vicinity? of the upper opening (13), and at which? connected at least one suction device (26), the section of the sliding duct (12) between the first smoke evacuation duct (24) and the second smoke evacuation duct (25) forming part of an evacuation path for the fumes produced give one or more? burners (6). Melting apparatus according to claim 10 wherein the supply apparatus (1) and a duct for discharging liquid zinc from the melting tank (3) are arranged at opposite edges of the melting tank (3).