Classifications

• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
  • C23C2/34—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor characterised by the shape of the material to be treated
  • C23C2/36—Elongated material
  • C23C2/40—Plates; Strips
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
  • C23C2/003—Apparatus
  • C23C2/0034—Details related to elements immersed in bath
  • C23C2/00342—Moving elements, e.g. pumps or mixers
  • C23C2/00344—Means for moving substrates, e.g. immersed rollers or immersed bearings
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
  • C23C2/325—Processes or devices for cleaning the bath

Definitions

• the present invention relates to a metallurgy process and it relates, in particular, to an improved method for coating a continuous metal product.
• the present method relates, for example, to a continuous hot-dip galvanizing process of semi-finished products such as metal strips and/or wires, normally wound in coils.
• the invention relates also to a structure that carries out this method.
• a continuous product for example metal strip or wire
• the coating metals useful to this end are those that have a melting temperature low enough to avoid thermal modifications of the products to coat.
• One of the most common coating processes is hot-dip galvanizing, with which a coating layer of zinc is topped to the metal strip or wire for protecting it from corrosion.
• continuous hot dipping is known, which allows treating continuously and quickly a large amount of material.
• the zinc coating is carried out by dipping the wire or metal strip in a bath of molten zinc that is kept at a temperature between 440-490 0 C by means of electric induction systems or by combustion of natural gas.
• the control of temperature of the bath is essential, since a too high temperature would cause an increase of the oxidation of the surface of the molten bath and then an increase of the floating dross thickness, whereas a too low bath temperature would cause an increase the viscosity of the molten metal that hampers the formation of a thin coating layer.
• the hot dipped metal strip leaves the bath with a certain amount of molten zinc on the surface.
• the metal strip is caused to pass through a plurality of air jets oriented towards its surface, by means of blade blowers located above the bath and shifted with respect to each other. This way, the excess of zinc is removed by blowing air or nitrogen and the system is usually adjusted by a thickness sensor of the coating metal.
• the outlet zone of the product to coat would be free from the risk of dross adhesion, since the emersion movement of the continuous product from the molten bath creates a vortical flow that keeps the floating dross away from the outlet zone.
• This vortical flow can be increased by heaters of the zinc bath that are located under the outlet zone.
• Another device as described in JP10140309, comprises a storage reservoir for collecting floating dross associated with a hot-dip galvanizing tank capable of separating the floating dross generated by the molten metal.
• the device comprises a means for conveying the molten metal from the hot-dip galvanizing tank to the reservoir.
• the reservoir provides a plurality of walls that are shifted from each other in order to make a labyrinth that causes separation of the floating dross, as well as of a dross accumulated at the bottom of the molten metal.
• the area and the size of the storage reservoir are so high that much power is consumed for keeping steady the temperature of the bath of molten metal.
• a galvanizing tank containing a molten metal bath suitable to coat said continuous metal product with a metal layer, said molten metal bath reaching in said tank a determined fill level and on said molten metal bath a floating dross layer is formed, said tank having an boundary edge;
• said step of removing said floating dross is made prearranging at least one zinc exit channel that extends along at least one part of said boundary edge of said galvanizing tank, said exit channel having a closed bottom and an upper edge, said closed bottom arranged below said fill level and at least one upper edge portion defining said fill level, such that said floating dross can flow into said exit channel at said upper edge portion and run in said channel parallel to said boundary edge up to reaching a collection point that is located at a level that is lower than said fill level and opposite to said outlet zone with respect to said inlet zone.
• the floating dross surplus which accumulates on the surface layer of the molten metal bath, by flowing into the exit channel with a part of the molten metal reaches quickly the collection point, while a thin layer of floating dross remains advantageously in the bath to protect the molten metal from oxygen and to limit heat dispersion.
• the fixed position of the upper edge portion of the exit channel where the outflow of metal occurs ensures that the level of the molten metal bath is maintained fixed, since the upper edge portion works as "overflow level" for the galvanizing tank.
• said collection point is located into a collection basin at which said exit channel ends and into which said floating dross and part of the molten metal is conveyed raising to a level that is lower than the fill level the tank.
• said collection step is carried out by prearranging said collection basin adjacent to said galvanizing tank so that the exit channel delivers in it the floating dross surplus and the amount of molten metal.
• the collection basin is immersed in the tank, in order to avoid masonry work for its installation at the edges of the galvanizing tank.
• a step is provided of automatic removal of said floating dross from said collection basin towards a disposal site.
• a step is provided of recirculating said amount of molten metal, which is accumulated in said collection basin, in said galvanizing tank by a pump that intakes the molten metal at the closed bottom of said collection basin.
• a pump that intakes the molten metal at the closed bottom of said collection basin.
• a step is provided of controlling the molten metal recirculation flow from the collection basin to the galvanizing tank.
• the exit channel in association to the collection basin and to the step of control allows to control the thickness of floating dross that must remain in surface.
• an apparatus for metal coating a continuous metal product in particular a metal strip or a wire, comprises:
• a galvanizing tank adapted to contain a molten metal bath to coat said continuous metal product with a metal layer, said molten metal bath reaching in said tank a determined fill level and on said molten metal bath a floating dross layer is formed;
• said means for removing said floating dross comprises at least one exit channel arranged within said galvanizing tank, said exit channel having a closed bottom and an upper edge, said closed bottom arranged below said fill level and said upper edge defining said fill level, such that least at one part of said floating dross flows down into said exit channel in order to be easily collected.
• the floating dross, and, in particular, the floating dross surplus which accumulates on the surface layer of the molten metal bath flows down into the exit channel with part of the molten metal, whereas advantageously in the bath a layer remains of floating dross adapted to protect the molten metal from the oxygen and to limit heat dispersion.
• the floating dross, near the outlet zone of the continuous metal product is withdrawn from exit zone of the product from the molten bath that creates a vortical flow that frees the outlet zone of the metal strip or wire, such that the floating dross cannot reach a level for which it sticks to the product at the outlet of the molten metal bath and does not cause rejects of production.
• the exit channel allows keeping the level of the metal bath fixed, avoiding expensive controls and monitoring operations of the level to obtain a valid final product, as instead necessary with the prior art.
• the upper edge of the channel has a function of "weir” or “overflow level”, maintaining always that level in a fixed way.
• said exit channel is arranged peripherally along said galvanizing tank such that said closed bottom and said upper edge are in said galvanizing tank. This way, the exit channel creates a gutter channel in the galvanizing tank that works as "overflow level" and gathers the floating dross surplus present on the surface of the molten bath along with a certain amount of molten metal.
• said exit channel has an upper edge having two heights, a lower height at said outlet zone that defines the filling level and lets to remove locally the floating dross present on the molten metal, and a higher height in all the other extension of the exit channel in the galvanizing tank in order to leave a protection of the molten metal zinc by means of the floating dross cover.
• the bath in the outlet zone of the metal strip is free of the floating dross in order, as above described, not to cause the floating dross to stick on the metal product, whereas the resting zone of the molten bath keeps a floating dross layer to protect from heat dispersion.
• a collection basin is provided associated with said exit channel in which said floating dross and part of the molten metal is collected.
• the collection basin is arranged adjacent to the galvanizing tank and separated from it, so that the exit channel delivers in the collection basin said part of floating dross and the amount of that has flown down the channel, and the floating dross cannot return to the tank.
• said collection basin is arranged within said galvanizing tank in order to allow a heat exchange from said galvanizing tank towards said collection basin.
• the temperature of the molten zinc in the collection basin remains substantially equal to the temperature of the zinc present in the galvanizing tank.
• said closed bottom of said exit channel is sloped with respect to the level of said molten bath for causing said floating dross and part of the molten metal to flow quickly towards said collection basin.
• the exit channel and the collection basin act as molten metal reservoirs, allowing to add a whole ingot into the tank without need to check the fill level. In fact, only the level in the channel and the collection basin grows.
• the collection basin acts as storage reservoir for the molten metal, such that it is possible to add different ingots at a time, saving manual work and simplifying the loading system the ingots.
• the collection basin is located under the conveying passageway, or "Snout" of the metal strip, in order to exploit that space and leave free other places in the tank.
• the floating dross is removed from said collection basin through lifting means that convey the floating dross to a disposal site.
• the floating dross that reaches the collection basin with part of the molten metal is withdrawn through a mechanical device overcoming the safety problems in case this step is effected manually.
• the a conveyor belt is provided, for example a grid-shaped belt, is dipped in the collection basin and exits from it in a sloped direction, conveying away the floating dross and leaving the molten metal free to fall again into the collection basin.
• said floating dross is removed superficially from said collection basin by a basket lifting means, comprising a basket integral to an arm, said arm rotatably connected about an axis, in particular said arm is arranged below said level of said molten metal and an rotate from a dipped position to an emptying position running through a draining position, wherein in said dipped position said basket is dipped into said molten metal; in said draining position said basket is arranged above said fill level such that the dross is drained from the molten metal in said basket; said emptying position reached after a programmable time, said basket slowing down quickly at said emptying position such that said arm is beaten suddenly against an abutment portion and causes said dross to fall down from said basket into a disposal site.
• said disposal site comprises an ingot mould that reciprocates between a loading position in which said dross is collected, to a discharge position, where the disposed dross is collected.
• the pump comprises a piston and a cylinder, which has two lateral apertures, a lower and an upper aperture.
• the piston has a diameter slightly less than the cylinder, in order to allow a calibrated leakage.
• An adjusting means is advantageously provided for adjusting the reciprocation pace of the piston responsive to the thickness of floating dross that has to be left to float on the molten metal of the tank.
• said exit channel is mounted on said galvanizing tank by a connection portion.
• the exit channel can be arranged on an existing galvanizing tank as retrofit.
• said exit channel is made in phase of construction directly in said tank.
• the channel is U-shaped, with an upper edge that works as weir, and the other edge, opposite to the channel, which protrudes upwards with an L-shaped portion, which can touch the edge of the tank, and then connected to it by means of suitable fixing means, for example screw connections.
• an adjustment means is provided associated with said exit channel, adapted to adjust the height of said upper edge and then of said fill level.
• connection portion - thickening laminas put between the connection portion and the edge of the tank; - a coupling that is slidable and lockable between the connection portion and the channel;
• connection portion between the connection portion and the upper edge stiffening elements can be provided, for example brackets, tie rods, stiffening ribs.
• FIG. 1 shows an elevational side view of a structure for coating continuous metal products, according to the invention
• FIG. 1 shows a top plan view of Fig. 1 , in which the flow is shown of the floating dross and of the molten metal towards the collection basin;
• FIG. 3 and 4 show respectively in an elevational side view and top plan view an exemplary embodiment of the structure that provides different means for removing the floating dross;
• FIG. 5 and 6 show instead the structure of Fig. 3 and 4 with the collection basin located out of the galvanizing tank;
• FIG. 7 and 8 show respectively a cross sectional view of the shape of the exit channel that is made within the galvanizing tank filled with molten metal
• FIG. 11 and the exemplary embodiment of Fig. 11' show a perspective view of the exit channel of Fig. 9, in which are shown respectively the stiffening ribs of the channel or the support elements;
• FIG. 14 shows a zinc exit channel that can also be made at the edge of the tank
• FIG. 26 shows an exemplary embodiment of the system for collecting the floating dross from a collection point to a storage and disposal zone.
• an apparatus for metal coating a continuous metal product, in particular a metal strip 15 or a wire (not shown).
• the structure comprises a galvanizing tank 10 containing a molten metal bath 11 , for example zinc, suitable to coat the metal strip 15 with a metal layer in order to obtain a zinc topped metal strip 15' and then a calibrated metal strip 15".
• strip 15 leaves the molten bath 11 along with a certain amount of metal liquid on the surface, indicated in Fig.
• the web 15' passes through a plurality of air jets slightly shifted from each other and oriented towards the metal strip, in the form of air blade blowers 29 arranged above the surface of the bath 17; this way, the excess of metal is removed from the metal strip by blowing air or nitrogen, obtaining the final metal strip 15".
• the molten metal bath 11 achieves into the tank 10 a determined fill level 17 given by the combination between the molten metal and the floating dross layer 12.
• the layer 12 represents a protection barrier for the bath, since it minimizes heat dispersion and keeps an insulation of molten metal 11 located underneath, which in turn would oxidize at the contact with oxygen causing a waste of molten metal, an excess of floating dross 12 leads to other problems described below.
• the continuous movement of the metal product 15, made by a mechanism 25, brings the product between an inlet zone 26 where the metal product enters in the molten bath 11 , a hot-dipping zone 27, where the product crosses the galvanizing tank 10, dipping in the molten bath 11 , and an outlet zone 28, where the metal product 15 exits from the molten metal bath coated by metal topping 15'.
• floating dross 12, near the outlet zone 28 of the continuous metal product 15, keeps at a distance from exit zone of the product in the molten bath 11 owing to a vortical flow that is caused in the outlet zone
• the metal strip 15 in hot-dipping zone 27 passes through a transport roller 13 and a respective counter-roller 14 in order to come out substantially in a vertical position.
• the metal strip or the wire then passes through, as above said, through the concentrated air blade blows 29 that control the thickness of the coating calibrating the amount of metal that is deposited on the outer surface of the continuous metal product 15".
• the structure comprises an exit channel 16 associated with galvanizing tank 10 and arranged peripherally along the latter.
• the channel 16 as better shown in Fig. 3 and 4, has a closed bottom 37 and an upper edge 38, the closed bottom 37 arranged below the fill level 17 of the tank 10, whereas upper edge 38 substantially at the level of the fill level 17, such that floating dross 12 flows down exit channel 16.
• exit channel 16 works as a gutter channel in galvanizing tank 10 that gathers floating dross 12 surplus present on the surface of the molten bath along with a certain amount of molten metal in order to work as overflow.
• upper edge 38 of channel 16 has a function of "weir” or "overflow level", maintaining always fixed level 17.
• a collection basin is provided 40 associated with exit channel 16 in which floating dross 12 accumulates along with part of the molten metal which has flown down into channel 16.
• collection basin 40 is arranged adjacent to galvanizing tank 10 such that suitably conformed exit channel 16 delivers in it the dross surplus and the molten metal amount that has flown down the channel.
• collection basin 40 is located under the conveying passageway 20of the metal strip 15, or "Snout" , in order not to hamper other places in the tank.
• Fig. 2 also the flow of floating dross 12 towards collection basin 40 is indicated.
• exit channel 16 and collection basin 40 act as molten metal reservoirs, allowing to add a whole ingot into the tank without the need to check the fill level. In fact, only the level in channel 16 and collection basin 40 can grow. By providing a sufficient storage reservoir, it is possible in particular to add different ingots at a time, saving manual work and simplifying the loading system of the ingots.
• a step of automatic removal of dross 12 from collection basin 40 delivers it to a disposal site 35.
• dross 12 joined to molten metal 11
• a lifting mechanism visible in Fig. 1
• the automatic device overcomes the safety problems when this step is effected manually.
• conveyor 31 for example a grid belt, is dipped partially in collection basin 40 and exits from it in a sloped direction, conveying away floating dross 12 and leaving the molten metal free to drop back into collection basin 11.
• conveyor 31 has then a plane portion 32 that allows floating dross 12 to be discharged precisely in bins 35 arranged below.
• conveyor 31 is moved by motor 90 arranged at plane portion 32.
• the disposal site is shown through a plurality of ingot moulds 35 that are shuttled between a loading position in which they receive the dross, to a discharge position, where the disposed dross is collected.
• FIG. 3 and 4 A further mechanism of removing floating dross 12, is shown in Figs. 3 and 4 and described correspondingly.
• the amount of molten metal 11 present in collection basin 40 is recirculated into galvanizing tank 10 by a pump 45 that intakes the molten metal at the bottom 11 so that it is not wasted but used again for feeding the molten metal bath of tank 10.
• a step is provided of controlling the molten metal recirculation flow 11 from collection basin 40 to galvanizing tank 10. This way, the control of the recirculation flow, in fact, in association to exit channel 16 and collection basin 40 allows to control the thickness of floating dross 12 that must remain on the surface of the bath.
• pump 45 comprises a piston 46 and a cylinder 47, which has two lateral apertures, a lower lateral aperture 48 and an upper lateral aperture 49.
• Piston 46 has a diameter slightly less than cylinder 47, in order to allow a calibrated leakage.
• the pump can comprise an impeller immersed in collection basin 40 that delivers directly molten metal 11 into the tank.
• an adjustment means is associated for adjusting the reciprocation pace of piston 46 responsive to the thickness of floating dross 12 that has to be left to float on the molten metal of the tank.
• FIGS 3 and 4 show an exemplary embodiment of the structure, according to the invention, where collection basin 40' is arranged dipped in galvanizing tank 10 so that the temperature of the molten zinc in the collection basin remains substantially fixed and in line with the temperature of the zinc present the tank.
• a heat exchange occurs between the molten metal and the walls of basin 40', in order to make uniform the temperature and transfer the heat of galvanizing tank.
• other heating devices are not necessary for keeping the molten metal at the desired temperature.
• changes on galvanizing tank 10 are not required and masonry work is minimum. Still advantageously, the technical time for executing the change are reduced and allow to save on the costs of installation. This solution is obviously possible if the size of galvanizing tank 10 permits it.
• floating dross 12 is removed superficially by collection basin 40 by a basket device 91 integral to an arm 92 pivotally connected about an axis 92'.
• basket 91 that normally is dipped in the molten zinc of collection basin 40, rotates from a dipped starting position 97 to a draining position 98 (visible in Fig. 5), substantially above the level of the molten metal, it waits for a determined time in order to drain the molten metal associated with floating dross 12.
• basket 91 moves up to an emptying position 99 where, after a determined time, ends its stroke with a sudden beat that causes arm 92 to stop against a shoulder portion, to shake the "scum" off from basket 91 into bin 35.
• arm 92 is moved by a motor 95 and the movement of basket 91 is protected by a shielding body 93.
• the structure of Fig. 5, 6, 7 and 8 may have exit channel 16 with an upper edge 38 with two heights, a lower height portion 16' in the outlet zone 28 of continuous metal product 15, in order to control the level of the zinc and a higher height 16", extending along galvanizing tank 10, in order to leave a thickness of floating dross 12 to protect the molten zinc.
• the zone covered by the dross is preferably that of inlet zone 26 of the product and the zone below the conveying passageway 20.
• the bath in the outlet zone 28 of the metal strip is free of the floating dross in order, as above described, not to cause the floating dross to stick on the metal product, whereas the resting zone of the molten bath keeps the floating dross to protect from of heat dispersion.
• Figures 7 and 8 show instead the exemplary embodiment of the structure of Fig. 5 and 6 with collection basin 40 located out of galvanizing tank 10.
• the tanks of the past galvanizing lines were smaller than the modern galvanizing lines, which are larger for keeping more easily the fixed level of the bath.
• the system described allows then to go back to tanks more compact fro saving energy and reducing the tons of zinc in fusion.
• Figures 9 and 10 show a cross sectional view of the shape of the exit channel 16, according to the invention mounted on galvanizing tank 10 by a connection portion 60 that is blocked, for example, through a plurality of screws 70 suitably spaced. This way, exit channel 16 can be arranged on an existing galvanizing tank as retrofit.
• the channel is U-shaped, with upper edge 38 that works as weir, and the other edge 38', opposite to the channel, which protrudes upwards and forms L connection portion 60, which can touch the edge of the tank suitably distant by means of portions 65, and then connected to it by means of suitable fixing means, for example screw connections.
• upper edge 38 can be made with different height, indicated respectively with H1 and H2, in order to adapt to the process and to the features of the molten metal present in the galvanizing tank 10, optimizing the thickness of floating dross 12 present in the molten bath.
• an exit channel 16 can be made adjustable in height for adjusting the height of upper edge 38 of the channel and then the fill level 17 of the molten bath.
• adjusting the height of upper edge 38 is obtained by raising the whole channel 16 through a plurality of thickness elements 67, shown in detail in Fig. 10, arranged above a head 69 of the edge of tank 10 and locked by screws 70.
• guiding elements are provided 71 adapted to keep aligned exit channel 16.
• connection portion can be provided between the adjustment means, not shown, for example a coupling can be provided that is slidable and lockable between the connection portion and the channel, screw lifting systems can be provided between the connection portion and the tank, or a upper edge can be provided that is movable for sliding with respect to the channel.
• FIG. 3 Another adjustment system, shown in Figs. 3 and 5, provides instead a plurality of wedge portions 19 that engage a respective housing 19' integral to the connection portion of the exit channel 16. This way an operator 100 can adjust the height and align exit channel 16;
• Figure 11 shows, perspectively, exit channel 16 of Fig. 9, in which stiffening ribs 75 are provided adapted to confer a better structural stiffness, whereas Fig. 11' shows the reinforcement of the channel made by means of suitably distant bracket elements 76.
• Figure 12 and the relative enlarged view of Fig. 13 show, in a diagrammatical view, galvanizing tank 10 with exit channel 16 that has a double height.
• this allows keeping a predetermined level of floating dross 12 in the zone under conveying passageway 20 that leads strip 15 into the bath, in order to minimize the energy consumption, whereas it allows to eliminate the floating dross at the outlet zone 28 of the strip.
• This is possible owing to a different height of upper edge 38 that works as weir for the molten metal flowing down.
• the height changes from a height H3 to a height H4 whose difference is ⁇ .
• Value of delta can be adjusted responsive to the kind of plant and of tank and is comprised between a few mm to several centimeters.
• exit channel 16 can also be made on the edge of the tank. With reference to Figs, from 15 to 19, exit channel 16 can be detached from the edge tank and cantilevered with respect to a collection basin immersed in the tank.
• exit channel may be U-Shaped and have side branches
• a central branch 16b reaches in 16c collection basin 40 that is immersed in the tank.
• Collection basin 40 has two compartments that communicate in depth with each other, and precisely a compartment 40b where the floating dross and the molten zinc enter from an inlet port 40c, coincident to the outlet of the channel 16c, and a compartment 40a where a pump is immersed that recirculates the molten zinc into tank 10.
• Collection basin 40 is kept immersed by the weight of the liquid zinc in it contained, which however reaches a level that is lower than the level surface in the tank, and by beams 170 anchored to a basement plate laterally to the tank.
• a heater 300 is provided in a tank zone that is left free laterally outside collection basin 40. This way, the heat of the heater keeps hot also the zinc present in collection basin 40.
• the ingots can be then dipped into the tank at this point close to heater 300
• the feeding step of zinc ingots is carried out laterally to the tank with a walking beam system 160. More precisely, walking beam 160 is arranged orthogonally to the tank edge above heater 300. The walking beam is mounted on a carriage 161, which is movable on wheels 162 that run on rails 163, and carries out a reciprocation and stroke predetermined by means of an actuator not shown. Arms 164 raise walking beam 160 in order to lift packs of ingots 20 that are arranged on saddle supports to B C D, in order to load at each stroke a stack of ingots on a lift 155 in position E.
• the latter is suspended by a frame150 on uprights 151 , and is lowered by an actuator 152, in order to dip the ingots in front of the heater 300 in the bath of molten zinc under the liquid surface 17 in a zone 10a of the tank 10.
• the loading operation of zinc ingots by walking beam 160 can be easily carried out by a loading means 180, and saddle supports A 1 B C D can be loaded all at the same time, giving to the walking beam a high autonomy.
• packs 200 can be also very large, since collection basin 40 and the overflow level system that is assured by the presence of upper edge portion of channel 16 maintains in any case zinc level 17 fixed.
• the floating dross 12 can be easily picked up from compartment 40b of collection basin 40 by the system of Figs. 26 and 27 through basket 95. It provides an arm 103 that rotates on hinges 101 up to beating the basket 95 against an abutment of ingot mould 108 where the dross is gathered. Ingot mould slides on rails 109 and can a large amount of dross so that it has to be emptied after many hours requiring very limited intervention by operators.

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• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Coating With Molten Metal (AREA)
• Application Of Or Painting With Fluid Materials (AREA)

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Cited By (7)

Citations (8)

• 2009
  • 2009-02-09 IT ITPI2009A000011A patent/IT1395468B1/it active
• 2010
  • 2010-02-09 WO PCT/IB2010/000244 patent/WO2010089666A1/en active Application Filing
  • 2010-02-09 ES ES10716866.8T patent/ES2444540T3/es active Active
  • 2010-02-09 EP EP10716866.8A patent/EP2454392B1/en not_active Not-in-force

Patent Citations (8)

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