Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
  • B22D35/00—Equipment for conveying molten metal into beds or moulds
  • B22D35/04—Equipment for conveying molten metal into beds or moulds into moulds, e.g. base plates, runners
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
  • B22D37/00—Controlling or regulating the pouring of molten metal from a casting melt-holding vessel
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
  • B22D41/00—Casting melt-holding vessels, e.g. ladles, tundishes, cups or the like
  • B22D41/04—Casting melt-holding vessels, e.g. ladles, tundishes, cups or the like tiltable

Definitions

• the invention relates to a method and arrangement for pouring molten material, such as molten metal, into a casting mold. More precisely, the invention relates to a method and equipment for casting anodes used in electrolytic refining.
• Controlled pouring and precise feeding in the casting mold is essential for example in connection with the casting of metal anodes.
• the next process step after the casting of metal anodes is electrolytic refining, where a prerequisite for achieving a high cathode quality and high efficiency is, among others, a homogeneous quality of the anodes with respect to both shape and weight.
• anodes are cast in open molds.
• the melt is conducted from the anode furnace for example along a chute to the intermediate trough of the casting equipment, from where the molten metal is further poured to the casting trough.
• the volume of the intermediate trough is remarkably larger than the volume of the casting trough proper, and it also serves as a balancing intermediate storage between the anode furnace and the casting trough.
• the quantity of metal contained in the casting trough at the beginning of the pouring step is somewhat larger than the quantity of metal to be administered in the casting mold in each batch. Usually the quantity of metal to be poured to in the casting trough is about double the quantity to be poured in the casting mold.
• molten metal is precisely administered in the open casting mold.
• the casting trough is never completely emptied, but a so-called copper base is left on the bottom.
• Modern anode casting is realized as an automated process in so-called casting tables, where the casting molds are shifted on a round casting table to the front of the casting trough.
• the feeding is controlled by means of monitoring the trajectory and motional speed of the casting trough as well as its weight.
• the quantity of melt to be poured into the casting mold of a copper anode is administered at the accuracy of 3 percentages.
• the anode weight is within the range 300 - 600 kilograms.
• the casting trough is provided with weight sensors.
• the pouring is controlled automatically, and it begins when the casting trough is filled with melt, the initial weight of the trough is measured, and the casting mold is placed in front of the casting trough.
• the casting trough is tilted so that the molten metal flows over the casting trough spout to the casting mold.
• the pouring is arranged to be stopped, when the weight of the casting trough is reduced for the amount of the target weigh of the anode to be cast. Then the casting trough is returned to its initial position to be refilled.
• the casting trough is typically left filled with metal, and the metal is allowed to be solidified in the casting trough.
• the casting trough is subjected to the necessary maintenance procedures, which often include the renewal of the whole lining of the trough.
• the present invention makes it possible that the casting trough can be completely emptied of metal, in which case the trough requires lesser maintenance operations.
• the anodes used in the electrolytic refining of metals are thick plates, with a thickness of about 30 - 100 millimeters.
• the height of the anodes is about 900 - 1 ,500 millimeters, and their width is about 700 - 1 ,200 millimeters.
• the electrode plates are suspended in a vertical position from the protruding brackets, so-called lugs, formed at the top edge of the plate, supported against the tank edges.
• the anode lugs are formed of the anode metal, often in connection with the casting process.
• an anode casting mold comprises a flat recess, i.e.
• the flow of molten metal contains a lot of kinetic energy, which in the pouring of the cast is directed to the bottom of the casting mold and to the melt already contained in the mold, thus causing spilling and splashing. Therefore it is essentially important that the melt pouring height is as low as possible. On the other hand, the kinetic energy of the melt also disturbs the weighing of the casting trough. For minimizing weighing errors, spilling and splashing, it has been attempted to make the pouring step as even as possible.
• the patent publication US 5,967,219 describes a method for pouring molten metal into a casting mold so that weighing errors are reduced and the pouring step is tranquil.
• the invention described in said publication is based on the design of the casting trough bottom and on a controlled trajectory of the pouring motion, which conforms to the shape of the casting trough bottom.
• the described motion of the casting trough must be peaceful and slow.
• this kind of slow pouring results in that the casting step becomes the bottleneck of the overall process.
• the object of the present invention is to eliminate the problems connected to the prior art and to realize a novel casting trough and method for pouring molten metal to a shallow and flat casting mold.
• Another object of the invention is to realize the feeding of the molten metal into the mold as rapidly as possible, so that the molten metal does not rise over the mold, and that the surface of the molten metal poured into the mold remains as tranquil as possible.
• the present invention is based on the basic principle that the direction and quantity of the kinetic energy of the melt to be poured in the casting trough is affected by the shape of the casting trough.
• the pouring of the metal into the mold is realized at a pouring height that is as low as possible, in order to prevent the metal from obtaining high potential energy for rising over the edges of the casting mold.
• the pouring is also realized so that the flowing of the molten metal obtains a high horizontal flow rate with respect to the vertical flow rate.
• the rapid pouring according to the invention is based on a large mass flow at the beginning of the pouring step.
• the weight-accurate casting according to the invention is realized by slowing the mass flow down at the end of the pouring step.
• choking is carried out by means of a choke element, such as a choke brick, arranged in the casting trough; the positioning and design of the choke element is such that an unchoked flow of the molten metal is realized at the beginning of the pouring step, and that a choked flow at the end of the pouring step ensures an accurate feeding in the mold.
• the choke element enables a rapid inclining of the casting trough, without the flow of the molten metal becoming uncontrolled.
• the flow profile of the molten metal discharged from the casting trough is essentially spread along the whole width of the anode mold.
• the flow is directed essentially horizontally towards that wall of the casting mold that is opposite with respect to the casting trough, i.e. the rear wall of the casting mold.
• the horizontal kinetic energy of the flow is first stalled as the melt hits the bottom of the casting mold, and then as the melt collides the pressure wall created by the molten metal already present in the casting trough.
• the spreading of the flow profile is realized by means of the design of the casting trough spout, for example a spout brick. Remarkable advantages are achieved by the invention.
• the invention enables a casting operation that is more rapid than in the prior art, and as a consequence, the capacity of the casting machine and the casting table are increased.
• the arrangement according to the invention essentially reduces the undulation of the molten metal during the filling of the casting trough and thus increases feasible casting volume. Owing to the invention, also the undulation of the molten metal in the casting trough is reduced.
• the fact that the casting operation is speeded up is also based on the fact that the start and end weighings of the casting trough can be made more rapidly, without waiting for the motions of the molten metal to end, and on the fact that the casting can be started at maximum pouring rate, without harmful spilling and splashing as a result.
• the wearing of the casting mold is reduced, and also the need for a coating agent spread in the mold is reduced.
• a casting trough according to the invention includes a bottom, a spout, side walls and a rear wall opposite to the spout, and the casting trough is provided with an inclination mechanism fitted with at least one weight sensor for monitoring the weight of the casting trough.
• the spout edge is essentially of the same width as the casting mold cavity, and the spout comprises side walls essentially parallel to the melt flow, and a curved, downwardly directed pouring surface.
• a choke element for slowing down the mass flow of the molten metal that is directed from the space between the rear wall and the choke element towards the spout.
• the frame of the casting trough according to the invention can be made for example of steel, in which case the lining of the trough is made by fireproof brickwork or by some other corresponding agent.
• the choke element of a casting trough according to a preferred embodiment of the invention is designed so that when fitting it in between the side walls of the trough, there is left, between the casting trough bottom and the choke element, an orifice of the desired size, irrespective of the skills of the engineer.
• the choke element is arranged so that in a casting situation, the orifice is located completely underneath the molten metal surface.
• the choke element can be a choke brick, and preferably it is a plate-like structure that is arranged in a perpendicular position with respect to the flowing direction of the molten metal and in an essentially vertical position with respect to the bottom of the casting trough.
• the choke element is dented at the bottom edge, so that the orifice is defined by the denting notches of the choke element and the bottom of the casting trough.
• the denting brackets may extend as far as the bottom of the casting trough.
• the choke brick can be formed by casting it permanently in the casting trough by means of a suitable mold, by brickwork or by fastening a suitable element to the casting trough.
• the employed fastening elements can be for instance steel wedges.
• the choke element is advantageously arranged between the spout and the rear wall, so that 40 - 90% of the quantity of metal of the object to be cast can be fed in the space of the casting trough defined by the choke element and the spout.
• the weight of the casting trough according to the invention is measured by means of one or several weight sensors arranged in connection with the trough tilting mechanism.
• the tilting of the casting trough can be realized by the mechanism suggested in the patent publication US 5,967,219.
• the tilting of the casting trough can be realized by a mechanism where the forepart of the casting trough is supported underneath against a stationary support, so that the casting trough can, when being tilted, turn with respect to said support, and the back end of the casting trough is raised by a lifting mechanism, such as a hydraulic cylinder.
• the tilting of the casting trough can also be realized by some other suitable mechanism.
• the flow of the molten metal proceeding from the casting trough to the casting mold is adjusted to the desired shape by the casting trough spout.
• the spout comprises a curved pouring surface directed downwardly from the casting trough bottom.
• the pouring surface is defined by the pouring edge of the spout and the bottom of the casting trough or by an element of the spout that is parallel with the bottom of the casting trough.
• the advantageous design of the spout according to the invention is realized by all spout forms that protrude from that element of the spout that is parallel with the bottom of the casting trough and divide the flow of the molten metal evenly along the width of the casting mold at the pouring spot.
• the pouring edge of the spout When viewed from the top, the pouring edge of the spout is curved, parabolic or with a variable radius. When viewed from the top, the pouring edge particularly advantageously constitutes part of the circumference of a circle.
• the pouring surface is widened towards the pouring edge.
• the pouring surface is defined by essentially straight lines drawn from the pouring edge to the bottom of the casting trough.
• the angle of the pouring surface with respect to the bottom of the casting trough can vary within the range 12 - 55 degrees.
• the pouring surface is a conic section.
• the width of the pouring edge is proportioned to the width of the casting mold cavity, so that the width of the pouring edge approaches the width of the casting mold cavity.
• the spout is a spout brick that can be manufactured separately.
• the spout brick according to the invention can be manufactured for example by casting in a moid.
• the material is some fireproof material, such as brickwork or cast iron.
• the spout brick designed according to the invention can be fitted in many casting troughs with different designs, so that the desired objects are achieved, i.e. an advantageous shaping of the molten metal flow, a desired flow rate and direction of the flow to the casting mold.
• the molten metal of the metal anodes is poured to a flat casting trough, from the casting trough the metal is poured to the casting mold, the mass flow rate of the molten metal from the casting trough to the casting mold is controlled for achieving an even casting surface, and by means of one or several weight sensors arranged in the tilting mechanism of the casting trough, the weight of the cast object is controlled.
• the mass flow rate of the molten metal from the casting trough to the casting mold is higher at the beginning of the pouring process, when at least 40%, preferably 70 - 80% of the cast metal is poured in the casting mold.
• the mass flow rate of the molten metal from the casting trough to the casting mold is controlled by means of a choke element installed in the casting trough.
• the mass flow rate is controlled by means of the trajectory of the casting trough.
• the mass flow rate is controlled both by means of the trajectory of the casting trough and the choke element of the casting trough.
• Figures 1 a and 1 b illustrate casting troughs according to embodiments of the invention.
• Figure 2a is a side-view illustration of a casting trough and casting mold according to an embodiment of the invention, seen from the direction of the casting mold.
• Figure 2b is a top-view illustration of the casting trough and casting mold of figure 2a.
• Figures 3a and 3b illustrate the casting trough and casting mold according to figure 2a, seen along the section A-A.
• Figures 3a and 3b also illustrate how the molten metal is placed in the casting trough and poured into the casting mold.
• Figure 4a is a top-view illustration of a spout brick according to an embodiment of the invention.
• Figure 4b is a side-view illustration of the spout brick of figure 4a.
• FIGS. 5a and 5b illustrate a choke brick according to a preferred embodiment of the invention.
• the casting trough according to figure 1a has a curved bottom 16, side walls 14 and a rear wall 13.
• the choke brick 12 is placed between the spout, in this case the spout brick 15, and the rear wall 13.
• the choke brick 12 divides the space defined by the bottom and walls to the casting trough forepart 11 and the casting trough back end 10.
• the notches made at the bottom edge of the choke brick 12 and the bottom 16 of the casting trough define the slots 19 through which the molten metal flows from the back end 10 to the forepart 11.
• the height of the choke element is advantageously chosen so that it extends from the bottom of the casting trough to at least the surface level of the melt, while the casting trough is in the filling position.
• the spout brick 15 has vertical side walls 17 and a pouring surface 9.
• the pouring surface 9 is curved downwards and widened towards the spout edge 18.
• the spout edge 18 is curved, and the pouring surface 9 is a conic section.
• the volume of the back end 10 of the casting trough according to the embodiment illustrated in figure 1 is larger than the volume of the forepart 11 , because the casting trough is widened at the choke brick 12 towards the rear wall 13.
• FIG. 1 b illustrates a casting trough according to a preferred embodiment of the invention, provided with a curved bottom 16, side walls 14 and a rear wall 13.
• the spout brick 15 has vertical side walls 17 and a pouring surface 9.
• the pouring surface 9 is curved downwardly and widened towards the spout edge 18. When viewed from above, the spout edge 18 is curved, and the pouring surface 9 is a conic section.
• the lining is made of fireproof brickwork, and the frame is made of steel.
• Figures 2a and 2b show a casting trough 30 and in front of it a casting mold for a copper anode 24.
• the casting mold 24 has an anode-shaped casting cavity 31.
• the side walls 27 of the casting trough continue in parallel and in a straight line as far as the spout brick 25 of the rear wall 23, in which case the bottom 26 of the casting trough is essentially rectangular when viewed from the top.
• the choke brick 22 is arranged at right angles to the side walls 27, and it extends from side wall to side wall.
• the bottom edge of the choke brick 22 is provided with two notches that define the slots left between the bottom 26 and the choke brick 22, through which slots the molten metal flows from the space 20 to the space 21.
• spout brick 22 Against the side walls 27, there are arranged three pairs of upwardly directed support beams 39 for fitting the spout brick 22 in the desired spot in between the rear wall 23 and the spout brick 25.
• the location of the choke brick can be adjusted at the spots defined by the three pairs of support beams.
• the choke brick 22 is supported in place by two wedges 61 and fastening elements 62.
• the arrows 28 show the direction of the molten metal flow as well as turbulences when the metal flows out of the casting trough 30 and settles in the cavity 31 of the casting mold 24.
• Figures 3a, 3b and 3c illustrate the embodiment of the invention seen in figures 2a and 2b, viewed along the section A - A.
• the casting trough 30 is in the filling position, filled with molten metal 32.
• the casting trough 30 is inclined for pouring, and the molten metal 32 flows from the casting trough 30 to the casting mold 24.
• the casting trough 30 is returned to the filling position after pouring.
• the bottom 26 of the casting trough is curved, so that the height h m of the molten metal remains low in relation to the length of the casting trough, when measured from the rear wall 23 to the spout brick 25.
• the spout brick 40 according to figure 4 is fitted in the casting trough.
• the spout brick can be manufactured for example separately, by casting of fireproof material.
• the spout brick comprises a pouring surface 49 and a bottom element 41 fitted in parallel with the casting trough bottom.
• the pouring surface 49 of the spout brick is curved downwardly from the casting trough bottom, and it is a conic section.
• the spout brick has essentially vertical side walls 42, 43. At the pouring surface, the side walls 43 are lowered towards the pouring surface edge 45.
• the corner radius of the edge between the surfaces 41 and 49 is preferably 0.5 - 800 mm.
• Figures 4a and 4b illustrate a spout brick according to figure 4 when installed in front of the casting mold 44 and above it, in operating position.
• the pouring surface 49 of the spout brick is widened towards the pouring edge 45.
• the radius of curvature r of the pouring edge is proportioned to the width A of the casting mold cavity, and the length of the radius of curvature r is advantageously 0.2 - 6 times the measure of A.
• the length B of the pouring surface depends on the chosen brick height E in proportion to the casting mold, and on the angle epsilon ( ⁇ ) of the cone surface in relation to the direction of the bottom element 41 of the spout brick.
• the size of the angle epsilon ( ⁇ ) is advantageously within the range 12 - 55 degrees.
• the width C of the spout brick is advantageously 0.3 - 0.95 times the width A of the casting mold cavity, particularly advantageously 0.5 - 0.8 times the width A of the casting mold cavity.
• the measure D of the spout brick surface 41 is chosen so that the spout brick is suitably integrated with the rest of the design of the casting trough.
• the operation of the spout brick is advantageously affected by minimizing the pouring height F.
• the pouring height can be for example within the range 70 - 400 mm, preferably 130 - 200 mm.
• the width K of the pouring edge 45 is advantageously 0.5 - 0.98 times the width A of the casting mold cavity, preferably 0.6 - 0.7 times the width A of the casting mold cavity.
• the choke brick 50 illustrated in figures 5a and 5b is provided with denting formed by three notches 51 , 52, 53.
• the height of the choke brick extends at least from the bottom of the casting trough to the level of the top edge of the side walls.
• the height hi of the notches is preferably 10 - 100 millimeters.
• the total area of the notches is preferably within the range 1500 - 17000 square millimeters. In practical work, the total area of the notches can easily be increased simply by breaking some dents off the brick. Consequently, for finding a suitable notch area, it is advantageous to start the casting with a choke brick provided with several dents.
• the essential factors are the height and total area of the notch or notches in the choke brick.
• the sum of the notch widths 11+12+13 is preferably 0.05 - 0.9 times the brick width It.
• the thickness dt of the brick can be less than 5 millimeters or over 100 millimeters, advantageously it is 5 - 100 mm.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Molds, Cores, And Manufacturing Methods Thereof (AREA)
• Casting Support Devices, Ladles, And Melt Control Thereby (AREA)
• Electrolytic Production Of Metals (AREA)
• Casting Devices For Molds (AREA)

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Publications (1)

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Cited By (4)

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Citations (7)

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• 2004
  • 2004-04-01 FI FI20040477A patent/FI120577B/fi not_active IP Right Cessation
• 2005
  • 2005-03-07 WO PCT/FI2005/000138 patent/WO2005095027A1/en active Application Filing
  • 2005-03-07 DE DE112005000742.1T patent/DE112005000742B4/de not_active Expired - Fee Related
  • 2005-03-07 CA CA002564631A patent/CA2564631A1/en not_active Abandoned
  • 2005-03-07 CN CNB2005800097985A patent/CN100553824C/zh not_active Expired - Fee Related
  • 2005-03-07 AU AU2005227642A patent/AU2005227642B2/en not_active Ceased
  • 2005-03-07 EA EA200601572A patent/EA008872B1/ru unknown
  • 2005-03-16 PE PE2005000298A patent/PE20060063A1/es active IP Right Grant
  • 2005-03-30 AR ARP050101219A patent/AR049795A1/es unknown
• 2006
  • 2006-09-14 ZA ZA200607694A patent/ZA200607694B/en unknown

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