NO142563B - PROCEDURE FOR CONTINUOUS MANUFACTURE OF SIZE-BASED ALLOY CASTING BLOCKS WITH LARGE SIZE. - Google Patents

Description

The invention relates to a process for the continuous production of a large zinc alloy ingot (commonly referred to as a "custom" zinc ingot) which is filled and melted in a coating bath in the manufacture of galvanized sheets.

Until now, large customized zinc casting blocks have been produced to order from users. The size or weight of such a zinc ingot varies within the range of 500-1000 kg,

and the casting block has an approximately rectangular parallelepiped-

ic form. Such casting blocks can, depending on the users' requirements, vary in terms of weight to a certain extent or within a range of

hand determined allowable weight range, but the content of alloy components and the size of the ingot are strictly specified. In the manufacture of the ingot, a large number of workers are necessary for each step and for the operation of the zinc melting furnace. Zinc and desired alloy metals are charged into the furnace and melted to produce a molten zinc-based alloy of predetermined composition, and the obtained molten alloy is cast in a fixed amount into a mold of a fixed size and whose cross-section is approximately concave-rectangular and parallelepipedic, after which the casting block is removed from the mold. With the recent increase in the production of galvanized sheets, the need for mixed zinc casting ingots has also increased, and with a production system where each step is dependent on human effort for the production of the above-mentioned "bespoke" zinc casting ingot, this need can no longer be satisfied. Much emphasis has therefore been placed on developing a production system that would make it possible to mass produce the "tailor-made" zinc ingot.

The invention thus aims to provide a method for the production of a large zinc ingot,

as the method must be particularly suitable for mass production and must also be able to be carried out continuously and mechanically at all stages from the production of the molten zinc-based alloy after the melting down of the raw materials for casting and removal of the ingot from the mould. With the help of the present method, the disadvantages that the production of zinc-based alloys in ordinary alloy furnaces are plagued with are avoided, and the present method through-

is then also fed into an alloy furnace which enables the continuous production of zinc-based alloys.

The zinc-based alloy ingot to be used for the production of galvanized iron sheets may be allowed to

have a certain varying composition in accordance with the users' requirements, but as a rule very strict requirements have been set for the composition of the casting block. In the production of molten zinc-based alloys for the normal production of zinc-based alloy ingots, a batch system has occasionally been used which enables a very simple regulation of the alloy's composition. All or almost all of the raw materials for the production of molten metal in the alloy melting furnace have first been added, after which the other raw materials have been added and mixed with the molten metal and the materials have then been melted, and the operation has been repeated. In this type of common production of molten zinc-based alloys, the melting method for such a simple batch system has been used, and it has therefore been necessary to use alloy melting furnaces with a relatively large capacity, and during the melting period for the zinc-based alloy when the raw materials are filled in, the casting of the ingot has had to be interrupted, and during casting the melting of the zinc-based alloy had to be interrupted.

For the present method, an alloy melting furnace has been developed for melting the zinc-based alloy and in which it is possible to continuously carry out a melting operation without having to interrupt the casting of the ingot.

The invention thus relates to a method for the continuous production of zinc-based alloy ingots of large size using an alloy furnace comprising a mixing furnace, at least one charging well which is connected to the mixing furnace through a side wall thereof, at least one stirring device which extends into the mixing furnace, a muffle furnace that is in connection with the mixing furnace, at least one discharge well that is in connection with the muffle furnace through a side wall of this, and a partition wall with is, overflow channel and arranged between the mixing furnace and the muffle furnace, whereby a zinc melt is produced, e.g. . in a melting furnace, after which a selected amount of the molten zinc and at least one alloy metal ingot are introduced into the charging well while stirring the molten zinc and while simultaneously melting the ingot to form in the mixing furnace a molten zinc-based alloy from the thus formed molten alloy metal and the molten zinc, and the method is characterized by the combination of the following steps: a) introduction of molten zinc and alloy metal ingots into the charging well is repeated at fixed time intervals and

the ingots thus added are melted and the molten alloy metal obtained is mixed with the molten zinc for continuous formation of a molten zinc-based alloy in the mixing furnace, the molten zinc-based alloy being periodically allowed to flow over from the mixing furnace past the partition and

into the muffle furnace,

b) a selected amount of the molten zinc-based alloy is periodically and sequentially cast from the muffle furnace for manufacture

of a large ingot of the zinc-based alloy by supplying the molten zinc-based alloy from the discharge well and introducing the molten zinc-based alloy into at least one casting mold, and

c) the amount of molten zinc and alloy metal ingot that is introduced into the charging well per unit of time is regulated so that

the quantity thereof introduced into the mixing furnace and the quantity of the molten zinc-based alloy discharged from the muffle furnace are kept approximately equal.

The main steps for the present method can thus be roughly divided as follows, with the alloy melting furnace being used in the third step: (a) Production of raw material (molten zinc) - 1st step, (b) continuous dipping and filling of a specific

amount of molten zinc - 2nd step,

(c) continuous production of molten zinc-based

alloy - 3rd stage,

(d) automatic casting of a certain amount of the obtained

molten zinc-based alloy - •+, step,

(e) automatic withdrawal of the zinc-based alloy stope block - 5th stage.

The present invention will be described in more detail below in connection with the sequence of steps shown on the flowchart (fig. 1) which, in accordance with the above-mentioned main steps, comprises 5 steps. In fig. 1 also schematically shows an arrangement of devices.

Step 1: Preparation of raw material (molten zinc)

According to the invention, it is aimed that even when a furnace with a relatively small capacity (the alloy furnace according to Fig. 1) is used for the production of molten zinc, the furnace's capacity must be able to be increased and the molten zinc-based alloy can be produced continuously in an amount substantially consistent with the discharge an amount of molten zinc comparable to the amount of molten zinc from a conventional large capacity furnace. For this reason, the zinc raw metal which forms the main component in the zinc-based alloy produced according to the invention is limited to having to be used in a molten state. Zinc raw material for the production of refined zinc, e.g. distilled zinc, electrolytic zinc or reflux distilled zinc etc., is therefore filled first and melted in the one in fig. 1 showed melting furnace for electrolytic zinc or melting furnace for distilled zinc and is kept molten within a desired temperature range. Instead of the above-mentioned melting furnace, a warming furnace for molten metal can also be used, and the raw zinc material can be temporarily filled and stored in such a warming furnace. The raw zinc materials will contain different polluting components depending on the refining method used, and two or more such raw zinc materials can, according to the invention, preferably be used after mixing, provided that the polluting components will fall within the acceptable range,' and in fig. 1 shows the use of two types of raw zinc materials. If only one type of raw zinc material is used, it will of course be sufficient to have only one melting furnace for the raw zinc material, while if three types of raw zinc material are used, three melting furnaces for the raw zinc materials can be used. These melting furnaces can be made of any type of melting furnace with a normal structure, but the furnaces must be provided with a suitable side wall, with the dilution, or the source for dipping the molten metal.

Step 2: Continuous dipping and charging of a specific amount of molten zinc

In this step, using a suitable in-

direct a certain amount of molten zinc which has been produced from the raw materials in the above-mentioned first stage, and is then charged into the furnace for producing the zinc-based alloy (alloy furnace) used in the third stage. In this step, any device that can be used to periodically fill a certain amount of molten zinc into the alloy furnace can be used, but it is preferred to use the device described below.

This apparatus comprises a recess for at least one pig zinc melting furnace or for the above-mentioned holding furnace, and a pump for constantly maintaining the surface of the molten zinc in the recess at a constant level is arranged near the recess to force an overflow of molten zinc by constant tapping of molten zinc into the recess from the furnace, and it is preferable to use a device which, when dipping, will remove a certain amount of the molten zinc that has been tapped into the pre-dip from the raw zinc smelting furnace or hot-holding furnace, and to fill the zinc from the recess above in the alloy furnace.

A dipping and charging device suitable for carrying out the present method for transferring a specific quantity of molten zinc will be described in more detail with reference to fig. 2, 3 and h.

A machine frame 3 is mounted in the upper part of a recess

2 arranged at the side wall of the raw zinc melting furnace 1, and a motor ■+ and a row reduction gear 5 are arranged in the machine frame. The motor h (a cyclo-motor with variable speed) can be regulated so that the speed can be changed from 6.1. to 2^-,<1>+ rpm, and the rotational speed of a camshaft 8 can be regulated within the range 2.2-8.8 rpm by means of the combination of gears 6 and 7.

A cam 9 is attached to the camshaft 8, and a suspension knee piece 11 is arranged on an annular suspension fixture 10 which can be rotated and fits into a channel in the cam 9. A rod 15 for vertical movement of a dipper 12 is suspended in the knee piece 11 ,

and with the help of these devices, a dipper 12 for collecting molten metal can be held tiltably in place. The dipper 12 is supported at one end by a support fixture 13, and a trough lh for transferring the molten metal is arranged near the well wall. The suspension knee piece 11 will move vertically when the cam 9 rotates, and the dipper 12 will, due to this movement, be set in a tilting movement, as the support armature 13 acts as a rotating

point. When, therefore, the level of molten zinc in the recess or well 2 is kept constant at all times, a certain amount of molten zinc is taken up each time from the well by the dipper, and as shown by the direction of the arrow in fig. 3, the zinc obtained in this way is filled into the trough 1<>>+. The dipper will have a more preferred rocking motion when it is brought to move vertically due to the suspension knee piece 11 and the rod 15 when this is suspended in a suspension fixture 16 which acts as a pivot point. It is also preferred to place a counterweight 17 on one of the ends of the rod 15 which is connected to the dipper, as the movement is thereby made easier, as shown in fig. 3.

In the above-mentioned apparatus, the dipper's capacity for collecting molten metal can be regulated, i.e. when e.g. the dipper during a dip retrieves 70 kg of molten metal, due to the fact that the rotational speed of the above-mentioned camshaft can be varied, the retrieval with the dipper of molten metal per hour is regulated within the range 9200-37000 kg. When e.g. as described in Japanese patent document no.606^/63 a pump that is used in connection with a feeder for molten metal or when a dipper pump for molten metal is used similar to that used in the fourth step described in detail below, the molten metal will continuously flow over the source 2 from the raw zinc melting furnace 1 and returned to the melting furnace due to the supply of the molten metal, and the amount of molten metal which is collected by a dip of the dipper can be continuously regulated by maintaining a constant level for the surface of the molten zinc 18. The rotational speed of the camshaft 8 is then set to a predetermined speed so that the amount of molten metal retrieved by the dipper per time unit can be regulated. As a supply device for the supply of molten zinc from the raw zinc smelting furnace 1 to the well 2, it is necessary to use a device with a considerably larger supply capacity for molten metal compared to the amount of metal that is picked up by the dipper per unit of time, and by means of such an apparatus, molten zinc can be supplied to the well 2 and molten zinc can be caused to flow over from the furnace to the furnace, whereby a constant level of the molten zinc in the well 2 can be maintained.

The trough lh for transferring the molten zinc can be used

for continuously feeding the molten zinc drawn by the dipper into the mixing furnace of the alloying furnace and also for feeding a fixed amount of molten zinc into the mixing furnace over a set time by connecting

an end part of the trough 14 to the well for supplying the raw material zinc to the mixing furnace as shown in fig. 1. It is also advantageous that, especially because a cyclomotor with variable speed is used as the motor, the amount of molten zinc collected by the dipper 12 in the course of a certain time can be regulated simply by setting the motor scale to a fixed value.

An apparatus as shown in fig. 2-h is the most suitable apparatus for use in the second step of the present method, and its construction will be explained in more detail below. This dipping apparatus for collecting a predetermined amount of molten zinc comprises (I) a supply apparatus for molten metal in a zinc smelting furnace provided with at least one well, the supply apparatus having a sufficient capacity to maintain a constant level for the surface of the molten zinc and is capable of continuous to supply molten zinc to the well from the furnace, (II) a machine frame mounted, on the well, (III) a variable speed motor arranged on the machine frame, (IV) a <p>suspension knee piece which is set in vertical motion when the cam rotates and which is attached to the cam connected to the shaft of the engine, (V) a trough for supplying the molten zinc and arranged near the well, and (VI) a dipper attached to the suspension elbow and supported in such a way that one of its ends will be dipped into the well at the lower limit of the knee piece and pick up molten zinc, while the dipper's other end will be lowered at the upper limit of the knee piece and thereby causing the molten zinc to empty into the trough used for supplying the molten zinc. The dipper is set in a tilting movement with a predetermined sequence per unit of time when the motor with a fixed rotational speed is started.

Step 3: Continuous production of zinc-based alloy.

In this step, a certain amount of at least one alloying metal is filled and melted in the alloying furnace for alloy formation with a certain amount of molten zinc that has been transferred from the well into the alloying furnace in the second step. Thereby, a zinc-based alloy with the desired composition is produced, and the molten alloy obtained is transferred to the fourth stage in which a specific quantity of the molten alloy is continuously poured out.

In the third step of the present method, an alloy furnace is used in which a mixing furnace with at least one open part for the introduction of the raw material or a depression for the introduction of the raw material and which is generally referred to as a well, is connected to a muffle furnace which is heated by combustion of air and a gaseous or liquid fuel, a partition being arranged in the connecting part.

At the upper part of this dividing wall is an overflow channel, e.g. a gap, formed in the space formed by the furnace cover wall, or a connecting hole into which molten metal can flow at a suitable level of the partition wall, or a recess in the upper end part of the partition wall, and when the level of the molten zinc-based alloy in the mixing furnace rises to above it set level, the molten zinc-based alloy will flow over the partition and into the muffle furnace. It is also preferred that in the mixing furnace there is at least one opening in the cover wall for the insertion of a stirring rod which is passed through the cover wall for stirring the melt.

The alloying furnace used in the third step of the present method is constructed as mentioned above, and it can be easily constructed by connecting the mixing furnace constructed in the above manner with a conventional alloying furnace or by making a chamber corresponding to a mixing furnace as herein described in the usual alloy furnace.

The third step of the present method is characterized by the fact that the molten zinc-based alloy with the desired composition is produced in the mixing furnace by means of the partition wall in the alloy furnace, and the obtained molten zinc-based alloy is transferred and then tightened into the muffle furnace, and the filling itself therefore does not need to be interrupted or stopped. It is thus a distinctive feature of the present invention that the raw material charging and mixing and melting are repeated periodically in the mixing furnace, whereby an increased volume of molten zinc-based alloy is obtained in the mixing furnace, the molten zinc-based alloy with the desired composition being only sequentially transferred to the muffle furnace.

The third step of the present method will be described in more detail below in connection with the drawings.

In fig. 5 shows a horizontal cross-section of an embodiment of an alloy furnace that can be used according to the invention, in fig. 6

is shown a longitudinal section g through the lengthening furnace according to fig. 5, and in fig. 7 and 8 show cross-sections taken along the lines A-A and B-B on

fig. 5.

In each drawing, 31 means a mixing furnace and 32 a muffle furnace, and the prescribed amount of molten zinc is filled into a well 33 which is in communication with the bottom of the mixing furnace, and then a prescribed amount of alloy metal stop block, e.g. an aluminum stop block, in the springs.

As explained above, the aluminum block, as shown in fig. 1, is filled in by using a suitable charging device which is able to supply the aluminum stope block at the desired time with one stroke. An opening for inserting a stirring rod or "lay" a stirring device is designated 35, and the stirring rod or stirring device is inserted through the opening to stir the molten zinc and thereby accelerate the melting of the alloy metal. The well 33 is similarly provided with a position-regulating mounting device 3^ for the stirring device, and in this position the melting and alloy formation can be accelerated. A dividing wall is denoted by 37, and as shown in fig. 8, an overflow channel 38 is formed in the middle of the upper end of the partition wall to accelerate the overflow of molten zinc, and only the portion of the molten zinc-based alloy increased due to the newly added raw material flows through the overflow channel, 38 and into the muffle furnace 32. Openings for one burner is denoted by 39, ^0 and J+l, and by direct heating with the help of combustion gas from the burners, a solidification of the molten zinc-based alloy when the molten zinc and the alloy metal are mixed can thus be prevented, and moreover the fluidity can be improved.

The molten metal which has been alloyed to the desired composition and which sequentially overflows through the weir is introduced through the molten metal inlet <*>+8 into the muffle furnace 32, and the molten metal is maintained at a temperature suitable for stopping a stopper block of the zinc-based alloy in that combustion gas from the openings 39,^0 and hl is blown along the wall of the muffle furnace ^9, as shown in fig. 6 and 7. The combustion gas is then led to an outlet opening 36 through the mixing furnace 31 and released upwards. The molten zinc-based alloy in the muffle furnace 32 flows from the molten metal discharge opening k-7 at the bottom of the furnace to a well 50, and a suitable amount of the molten zinc-based alloy from the well 50 is discharged into a ferm for stopping the block. Openings for removing slag from the furnace are denoted by h2, h?>, k-k, k-5 and MS, and according to the invention it is preferred to use at least one opening to remove the slag, as mentioned above.

The furnace wall, partition and well in the above-mentioned alloy furnace are made of refractory stone which is resistant to the molten metal, and part or all of the surface of the furnace wall part may be reinforced, preferably with an iron or steel jacket. In order to keep the molten metal within a suitable temperature range in the alloy furnace, it is also advantageous to regulate the temperature by regulating the amount of combustion gas using measuring holes 51 and 52 for measuring the temperature of the combustion exhaust gas and using measuring holes 5h and 55 for measuring the molten bath temperature.

There is also a chimney for the removal of combustion waste gas

arranged on the upper part of the mixing oven 31 exhaust gas opening 36.

According to the invention, the stirring in the mixing furnace 31 °g the well 33 can be carried out with the help of an iron or steel rod, but to avoid as far as possible a contamination of the molten zinc-based

alloy is preferred, e.g. to use it in fig. 9 shown conversion device which rotates and converts the molten metal by means of engine power and where a conversion rod of refractory material,

e.g. a silicon carbide rod with an encircling blade attached to its end is inserted.

In fig. 9 shows a longitudinal cross-section seen from the front of the conversion device where a coupling 6^ is attached to an end part 63

of a support shaft for a rod 61 with a revolving vane 62 at its lower end, the devices being rotatable as a unit. The rod 61 can be produced by mixing a suitable binder

in the silicon carbide with sintering of the mixture at high temperature after it has been given the desired shape. The rod 61 can also be produced by sintering or melting and stuffing one or more of such materials as other refractory materials,

e.g. zirconium dioxide, aluminum oxide, silicon dioxide and magnesium oxide, or it can be made of a heat-resistant steel material. As coupling 6h to connect the rod 61 with the rotation shaft 65, it is preferred to use a flange coupling as shown in fig. 9.

A roller bearing 67 and a radial bearing 68 are fitted in both end parts of the shaft to enable the placement of a rotatable water jacket 66 on the pivot shaft 65. The roller bearing is held in place by means of a gasket 69 and a nut 70, and both end parts ;' £.'..of the roller bearing is sealed by means of oil jef or seals 71 and 72. Furthermore, the radial bearing 68, in a similar way to the roller bearing 67, is held in place by means of a gasket 73 and a nut 7^, and both end parts of the radial bearing is sealed using oil seals 75 and 76.

The water jacket 66 is used to prevent a temperature increase in the rotation shaft 65 and the aforementioned bearing devices due to heat conduction and heat radiation from the molten metal and also to achieve a smooth rotation. The water jacket 66 consists of cylindrical double side walls with a space 77 through which water flows,

and washing water is introduced through a plug 78 in the outer wall and drained through a plug 79. The turning mechanism is protected by means of water jacket covers 80 and 8l placed over the openings at both ends of the water jacket. Also, at the upper end of the turning shaft 65, a metal fitting 8<*>+ is arranged on the water jacket 66 for attaching the stirring device via the water jacket 66 to a suitable machine frame so that, when the motor is rotated by means of the pulley 82 for V-belts, to prevent the shaft 65 from vibrating <p>g also to prevent dv refractory stones 83 in the furnace top being exposed to the weight of the stirring device.

To the right below the rod 61 connection 6<*>+, a mufflecor-like sealing blade 85 is fixedly arranged and fitted into a channel 87 in the sealing ring 86 which is attached to the refractory stones of the furnace top, and a low-melting metal, e.g. lead, is filled in the channel. With this form of sealing mechanism, the sealing ring 86 will be heated due to heat radiation from the molten metal, and the metal in the channel 6/ry 1th will melt, whereby an ingress of atmospheric air during use of the stirring device will be prevented and, moreover, the rod 61 will rotate smoothly.

In the third step of the present method, only molten zinc is filled into the well 33 to complete the mixing of the molten zinc-based alloy of uniform composition, as mentioned above, in the well and the mixing furnace, and at the same time to achieve a complete melting of the alloy metal, e.g. e.g. an aluminum stop block. Namely, this is the most efficient way of supplying the zinc which forms the main component of the molten mixture for filling in the form of blocks, in order to be able to introduce molten zinc-based alloy into the alloy furnace in an amount that most closely corresponds to the amount of molten zinc-based alloy to be removed or collected up from the alloy furnace at approximately specific times for filling out in the form of block blocks. In the third step of the present method, the stirring is also carried out in the mixing furnace to speed up the alloying process by means of the above-mentioned stirring device, thereby melting the alloy metal into the molten zinc within the predetermined limited time available.

Fig. 10 shows a diagram with a curve 1 for the added amount of raw material ink as a function of the added amount of aluminum stop block in the production of a molten ■ zinc-based alloy containing approx. 0.23% by weight of aluminum in the mixing furnace, and also with a curve 2 for the necessary time (in minutes) to achieve an ideal melting of the aluminum stop block added according to curve 1 in the added zinc raw material, depending on the added zinc amount. If the molten zinc-based alloy is removed from the alloy furnace in a quantity of approx. 6 tonnes per hour, the aluminum stop block in relation to 6 tonnes of molten zinc raw material will be melted in a quantity of 13.8 kg per hour according to curve 1, and the molten zinc-based alloy thus formed must be fed to the alloy furnace. If, however, the aluminum stop block is supplied in the form of a 5 kg piece which is readily available in the trade, the time required to achieve the above ideal melting will be determined by the time (in minutes) for melting the 5 kg piece in accordance with the supplied quantity per time unit of the above molten zinc. If it is thus required that the molten zinc-based alloy be produced in an amount of approx. 12 tonnes per hour, it is necessary to add a 5 kg piece of solid aluminum per about. 11 minutes. It will then produce approx. 2.2 tonnes of molten zinc-based alloy per about. 11 minutes. When the molten zinc-based alloy of fixed composition and in a desired amount in the course of the above-mentioned limited time is introduced into the muffle furnace, the temperature of the molten zinc when the aluminum stop block is added will greatly exceed the effect on the necessary time for melting the stop block. An investigation has been carried out to demonstrate how the molten quantity of a 5 kg aluminum stope block will vary with varying temperature in the molten zinc, and the results are reproduced in the table 1 below.

The results reproduced in Table 1 were obtained when three aluminum stope blocks, each weighing 5 kg, were placed at approx. 6.5 tonnes of molten zinc and the molten zinc was stirred by hand with a steel rod during the production of a molten zinc-based alloy containing approx. 0.23% aluminum. It has also been established that results similar to those reproduced in Table 1 are obtained at the same melting conditions when aluminum stop blocks each with a weight of about. 2 kg, approx. 3 kg and approx. h kg is melted.

Although in the third stage of the present process

way the molten zinc's temperature will vary in accordance with the removed amount of molten zinc-based alloy from the alloy furnace per time unit, it is preferred in the fourth step described below to keep the molten zinc removed from the second step for filling in the well 33 of the mixing furnace 31 at a temperature of at least approx. 500°C, and with the help of such temperature regulation, it is possible per 30-50 tonnes of molten zinc-based alloy are produced per hour. Furthermore, the molten zinc-based alloy which has been produced in the mixing furnace 31 after the first addition of the raw materials can be kept within a desired composition range for the zinc-based alloy stope block, i.e. that the specified content of each component in the mixture can be maintained as only the amount melted zinc-based alloy corresponding to the quantitatively increased amount due to the second charging of the raw material is introduced into the muffle furnace 32. As mentioned above, a process similar to a periodic extrusion of jelly with a regulated content of constituents is repeated, and it is therefore possible to feed it molten alloy from the mixing furnace into the muffle furnace in accordance with any amount of molten alloy per unit of time which is picked up from the muffle furnace by immersion and by correct regulation of the time between such a periodic extraction process. An amount of the molten zinc-based alloy corresponding to the amount of molten zinc-based alloy to be collected by dipping for ordinary plugging, or an amount of zinc-based alloy in excess of such amount, can be retained in the muffle furnace of the alloy furnace, and the plugging of the molten alloy and the melting of the raw materials can therefore be carried out almost continuously without interrupting the process.

The third step of the present method is

above has been explained in connection with the use of an aluminum stop block as an alloy metal, but it is self-evident that in addition to a

aluminum stop block can any type of materials, such as a zinc-based alloy containing aluminum, magnesium or

copper etc. or various types of alloy components required by the users are alloyed into the molten zinc by treating them in a similar manner to the aluminum stop block. Such an alloy metal can also be added in certain quantities to mixing

the furnace by means of a mechanical device, and when the supply of the specific amount of alloy metal is adjusted in relation to the

forte specific amount of molten zinc which closely corresponds to the amount of the molten zinc-based alloy to be removed from the alloying furnace,

the third step can be easily carried out by a small number of workers. IN

in the third step, moreover, the molten zinc-based alloy can be produced practically continuously, and even if the amount of molten zinc-based alloy to be consumed per time unit becomes very large, the alloy furnace itself can be made with a relatively small capacity.

In this third step, it is a necessary condition to use the raw material zinc in a molten state, and for this reason it is necessary to use the melting furnace for the zinc raw material or the heating furnace for the molten metal as described in connection with the first step, but even when using different types zinc raw materials whose content of lead, iron and/or cadmium etc. varies, it is advantageous that the content of the constituents in the molten zinc can be easily regulated by changing the • mixed amounts of zinc raw materials in the mixing furnace. In the zinc refining furnace, raw zinc can also be produced in a molten state, and this raw zinc can then, according to the invention, be used as such and costs for the provision of melting heat are saved.

It should also be noted that for the maintenance of a

suitable stopping temperature for the molten zinc-based alloy, it is preferred to measure the temperature of the molten zinc-based alloy in the muffle furnace 32 and to provide a temperature measuring hole near the source 50, as shown in fig. 5, to regulate the heating temperature and the stop temperature of the molten zinc-based alloy.

Step h. Automatic stopping of a set amount of molten zinc-

based alloy.

In the fourth step of the present method, a specific quantity of the molten zinc-based alloy produced in the third step with the desired composition is automatically stuffed into a mold sequentially. An apparatus is used in this step for pouring out a fixed quantity of the molten alloy, and the stoping apparatus is arranged at the source 50 of the alloying furnace used in the third step. ■ '

Roughly outlined, the apparatus consists of a level detection device for detecting the level of the surface of the molten alloy in a specific position when the molten alloy is stopped in the mold, and a dipping vessel for transferring and stopping the determined amount of molten alloy in the mold from the alloy furnace, and these devices are arranged in the positions shown in fig. 1. The stop device is equipped in such a way that the stop will be started when the mold has moved to a position immediately in front of the stop device, and this stops the stop on receiving a signal from the device for detecting the surface level, as electromagnetic switches and limit switches are used at each part of the operation in the respective devices and each operating part is arranged in such a way that the operation is carried out in a fixed ±id upon receipt of the operation orders.

Step h of the present method will be described in more detail below in connection with an embodiment of the stop device as shown in fig. 11 and 12.."

Of these, fig. 11 a side view of the stop device arranged on the alloy furnace well 50 and fig. The I2 device according to fig. 11 sets'

from above.

The device 91 for detecting the surface level and the dipping device 92 are arranged practically in series, and the mold 93 on the mold support part 96 is transferred to the right downwards in relation to the detection device 91 by means of angle iron 97 which is in connection with a mold drive device (not shown) which acts on the wheels 9^ and 95 for transporting the mold which are arranged essentially parallel to the springs 50. The support shaft of the mold 93 is eccentrically and inversely supported and constructed in such a way that the stop block can easily be pulled out after finishing the stop by turning the mold upside down on

a place other than the place where the stop device is arranged. The turning of the stop block and the extraction of the d°nn<p> will be described in more detail below in Corbindelse with step 5 of the present method. It is preferred that the support part 96 of the mold is made of a circular turntable, and a drive device is installed in the center of the turntable or along an outer circumference thereof, and several pieces or about a dozen pieces of angles 97 protrude to guide the mold from the apparatus, whereby the mold can be sequentially transported .'-v;'

by a 360° rotation. The mold 93 can be stopped in a certain position by e.g. to transmit the operation order from the limit switch which is arranged in a position where it can come into contact with the mold 93

and in a position close to said fixed position, to the driving device for the mold. At the same time as the drive device for the mold stops, the stop is started using the stop device. A carbon electrode 98 for the detection device 91 is then lowered to a predetermined position by means of a cylinder 99 (containing compressed air) for raising or lowering the carbon electrode, and a tapping opening 101 in a trough 100 for the dipping device 92 for transferring the molten alloy from the source 50 is lowered to a predetermined position by means of a cylinder 102 (containing pressure oil) for raising the tap opening 101. When the tap opening 101 of the trough 100 and the carbon electrode 98 have been lowered to a predetermined position, a pump is set

103 underway to collect the molten alloy. This pickup pump 103 consists of an air motor 10<*>+ to drive the pump, a supply line 105 for compressed air and a pump line 106 for molten metal, the lower end parts of the supply line for compressed air and the pump line being arranged so that molten alloy will be blown up

at the end part of the pump line to the discharge opening 109 for molten alloy by means of the compressed air emitted from the end part of the supply line at the bottom of the well 50 of the alloy furnace. The molten leg-

Filling from the discharge opening 109 is filled into the mold 93 by lowering the trough 100, and the surface of the added molten alloy will rise in the mold. When the surface of the molten alloy comes into contact with the carbon electrode 98 of the level detection device 91, both connection ends of an electromagnet 110 arranged on the upper part of the electrode are short-circuited, and the electromagnet will thus be activated.

A switch mechanism is designed so that the actuation of the level detection device's 9l electromagnet 110 can be influenced by connecting one of the electromagnet's connection coils. to the electrode 98 and the other connecting pole to a suitable part of the mold, whereby the power source will be connected by contact between the surface of the molten alloy and the electrode. When this switch is turned on, the carbon electrode will be attracted by the electromagnet and separated from the surface of the molten metal.

It appears from fig. 11 that the electromagnet 110 and the carbon electrode 98 are raised together to above the mold 93 by the cylinder's 99 lifting arm. At the same time as the electromagnet 110 is started, the movement of the transfer pump 10'3 5' and the cylinder 102 stops. arra is raised for lofting the tap outlet 101, and the molten alloy remaining in the trough and the molten alloy supplied to the trough due to the rotation of the air motor lOM- for operating the pump 103 are returned to the well 50. However, it is possible to fill the entire the amount of the remaining molten alloy in the trough into the mold by ex-

set the movement of the cylinder for raising the trough 100 by means of a timer. The trough 100 is set in a tilting movement when the cylinder for raising or lowering the tap opening is started,

because of the trough carrier part 112 which is arranged on the wall of the well 50 and constitutes a pivot point.

In fig. 13 shows a schematic diagram of the systems used for each part of the stopping apparatus, and it is clear from this diagram that a predetermined operating plan from the punching of the mold '93 until the ^-stopping is finished can be carried out automatically by f orbinc ! ■) each part electrically by means of four limit switches and four electromagnetic switches. It should also be mentioned that in the switch mechanism which is affected by contact between the carbon electrode 98 and :;. the above surface of the molten alloy, is. to avoid current leakage to the other parts of the apparatus it is advantageous to ground a suitable conductive part that comes into contact with the mold 93. ' ■ \;'..

According to an embodiment of the stdpe apparatus described above, the trough can be divided into two parts, as the trough near the 'pump for transferring the molten alloy is only set' in tilting motion, and with this embodiment, the molten alloy that is emptied due to the inertial rotation can after the air motor 10^f has been switched off, is fed back to the source 50. That; however, can be seen from fig. 11 that now£<e>Senyttés e.tt trough, the molten alloy which is emptied due to inertial rotation after the air motor has been switched off, can be fed back to the source before it enters the mold, and in the production of a zinc-based alloy stbpe-

block of 1000 kg, the variation of the block's weight can thereby be regulated to approx. in ho kg. Furthermore, when the carbon electrode 98 comes into contact with the molten alloy, the reason why this will immediately rise and separate from the surface of the molten alloy is mainly that the electrode is exposed to very strong wear if the end of the electrode is kept in contact with the surface of the molten alloy and because the detection of the level of the molten alloy becomes erratic when the molten alloy adheres to the end of the electrode. If

if an electromagnet with a longer reach is used in connection with the stop device, it is also not necessary to use the cylinder mechanism to raise the earbone electrode.

Step 5. Pouring out a certain amount of molten zinc-based alloy.

In step 5 of the present method, the stop block is automatically removed from the mold after a certain amount of the molten zinc-based alloy in step Ver has been stopped in the mold and has solidified.

In fig. 1 shows a preferred embodiment of the present method which makes it possible to carry it out in the fastest way, and it should be noted that in the drawing a mold transport device of the circular turntable type is used and that the mold transport device is divided into five zones, i.e. a stope - zone for stopping a certain amount of the molten zinc-based alloy, i.e. in step ^f, a dross collection zone, a zone for cooling the stop mold and the stop block with pressurized water, a zone for automatic removal of the stop block, nozzle. in step 5, and a zone for preheating the mold. In any one of these zones, predetermined operations are carried out simultaneously. However, the invention is not limited to the arrangement of each apparatus and of the mold transport apparatus in step h and step 5 as shown in fig. 1, but it is possible e.g. to use a mold transport device which parallely extends further in relation to the position in the vicinity of the source in order to pick up the molten zinc-based alloy from the alloy furnace during immersion. The mold transport device can • therefore e.g. be arranged parallel to that in fig. 1 showed the trough of the stoping apparatus, i.e. that the form is placed on the transport mechanism or the transport rail which is arranged for transporting the form to the end part of the trough, as shown in the drawing, and step 5 of the present method can therefore be carried out both at the right and left end. If dross should develop on the molten zinc-based alloy plugged in step 1+, it is preferable to skim off and remove the dross as the molten zinc-based alloy solidifies,

and to facilitate the collection of the dross, it is beneficial to preheat the mold to approx. 160°C for the molten zinc-based alloy is plugged out. The molten zinc-based alloy filled out in step h of the present method is also preferably cooled and quickly solidified, e.g. due to the forced cooling of the mold transport apparatus with cold water, as shown in fig. 1, but

the mold transport apparatus can also be disconnected by means of a stream of cold air or by keeping the apparatus in cold air.

In the fifth step of the present method, a mold apparatus is used which comprises (I) a parallelepiped metal mold with two main shafts which are arranged eccentrically in relation to the central part on the outer surfaces of the longitudinal side walls of both end parts of the mold which have an almost concave -rectangular cross-section, with both prop shafts being rotatably supported, (II) a drive motor for tipping and provided with a suitable part for insertion into or removal from one of the prop shafts' end part and which integrally tips the prop shaft and the mold in the eccentric direction. The drive motor is arranged near the transverse direction of the mold and can be moved back and forth for coupling with the cylinder mechanism to remove or insert the fitting part

in the main shaft.

(III) a post for receiving stbt and which is held in such a position that it will collide with the upper end part of the long side of the form wall when the mold is tipped over 180°, and (IV) a bar for receiving a block of support and arranged at a lower part of the form.

In the use of the present molding apparatus, after a certain amount of the molten zinc-based alloy has been cast and cooled and has broken, the cylinder mechanism is started to bring the drive motor forward, and the adapted part is inserted into the end part of the mold support shaft and the mold tipped over more than approx. 150°, after which the drive motor is retracted after the adapted part has been freed from the end part of the mold's vertical shaft, whereby the stop block is pulled out of the mold. This is because the mold and stop block are rotated due to the displacement of the center of gravity of the mold and the rotational energy supplied to the stop block, whereby the mold and stop block are accelerated and the upper end part of the side wall of the mold collides strongly with the stbt receiving post. In this assembly, the stop block is released from the mold and taken up on the rod for receiving the stop block.

When using the mold apparatus in the fifth step of the present method, it may happen that the stop block is pulled out due to the impact of the stick when the mold is rolled over once, but the rolling of the mold can be constantly repeated after the mold has returned to its original position, and even if the stop block should stick to the mold, the stop block' can therefore be withdrawn without the use of human labor simply by repeating the rolling two or three times. When the stop block removed from the mold is received on the stop block receiving bar^ it will moreover is fed to the outside of the molding apparatus, for example by means of the conveyor for transporting the stope block, as shown in Fig. 1. This transport mechanism is so arranged that it will move the receiver rod back and forth, and at the same time a loft device is arranged downwards along the receiving rod, and after the stop block on the receiving rod has been lifted using the lifting device, the rod is pulled for receiving a v the stop block back, and when the device is so extended that the stop block is to be picked up on the roller conveyor when the ceiling device is in its lower limit position, even a stop block with a weight of over 1 ton can be fed to the outside of the forming apparatus without the transport machine for transporting the stop block being exposed to shock. •

Step 5 of the present method will be described in more detail in the form of an embodiment with reference to the drawings.

In fig. 1*+ is the form apparatus shown from above, in fig. 15 is shown

a side view with a vertical cross-section of the mold part, and in fig. 16

is shown; a side view with a horizontal cross-section of the mold part. - In fig. lh, the mold 93 is shown attached to the web 112 for transporting the mold, and the mold and the web are simultaneously transferred to the predetermined position and a certain amount of the molten zinc-based alloy is extruded from the stepper used in step h of the present method. The mold stops in the position where the tipping drive machine 11^ and the support receiving post 115 are arranged. The mold 93 is held at a constant level by means of a horizontal holding cage piece 116 to keep the mold horizontal, the mold support shafts 117 and 118 being concentric. Radial ball bearings are attached to the mold support shafts 117 and 118 and to the rails 112 and 113 by means of stationary clamping devices 119 and 120.

The rails 112 and 113 are provided with wheels which at their lower end parts are in contact with sliding rails 121 and 122, and the mold 93 together with the rails 112 and 113 can be moved back and forth with the help of the knee piece 123. At the end part of the mold support shaft 118 is attached a stationary side connection 12<*>+ with the one in fig. 17 and 18 shown design, and a stot side coupling 126 with the one in fig. 19 and 20 shown design is attached to the rotation shaft 125 of the second roller drive motor llh. When this is moved forward by means of the cylinder 127 which is used to move the roller drive motor llh back and forth, as shown in fig. 17, the side link 126 will abut against the stationary side link 121+, and when the roller drive motor llh is running, the mold 93 will be rolled over or tipped over as indicated in fig. 16. When the form 93 is tipped by the form's center of gravity being transferred from the drive motor side to the side towards which it is tipped, it will assume a position (angle position) where it can roll over even if the external force is removed, and the roll or tilt drive motor is pulled back and the mold 93 will bump against the bump receiving posts 128 and 129 of the support bar 115. It is therefore advantageous to use support bodies 130 and 131 as shown in the drawing and which are designed in such a way that the fins of the mold 93 will be reinforced and which will simultaneously bump against the support posts.

When the mold is tipped, the stop block will fall onto a forked rod 132 for receiving the stop block which is transferred from the rod for receiving the stop block to four rod pieces 13^, 135, 136 which form part of the lifting device 133 for lofting the stop block, by the rod pieces which are arranged just below the rod 132 for receiving the stop block, is raised. The rod 132 for receiving the stope block is then retracted by means of the cylinder 137, and each rod piece 13^, 135, 136 which forms part of the loft device 133 for lofting the stope block, is lowered and the stope block is placed on the roller conveyor 138 to transport the stope block out. The raising and lofting of the device for lofting the stopper block when the stopper block is transferred to the roller conveyor I38 is carried out by means of the pressure oil cylinder 139.

The sequence of steps when using the device in step 5 of the present procedure is described in the correct order below.

(a) The mold 93 in which the molten zinc-based alloy is cast and broken is punched in a specific position (a position where the

is aligned with the roller drive motor 11<*>+).

(b) Rod 132 for receiving the stop block is moved forward

(preparation to receive the stop block).

(c) The roller drive motor ll*f stbt side link 126 is brought to lie

against the stationary side connection 12^ of the mold 93.

(d) In the middle of the tipper manbover with the tipper drive motor llh, this is pulled back (the form rolls over freely, and when the stbtbodies

130, 131 as a result of the free rolling of the mold abuts against the stop bars 128, 129, the stop block falls out and onto the bar for receiving the stop block). (e) The device 133 for lofting the stop block is raised (the device for lofting the stop block will be above the ceiling device in its upper limit position). (f) Rod 132 for receiving the stop block is retracted. (g) The device 133 for lofting the stop block is lowered (the stop block is placed on the roller conveyor 138 when the loft device is in its lowest position and transported out of the apparatus). (h) The tilting drive motor's stot side coupling 126 is brought into contact with the stationary side coupling 12^- of the mold 93, and when this is tipped, it will return to the starting position.

The apparatus used in step 5 of the present method comprises a limit switch arranged in the position in which the mold 93 is when it has been punched according to step (a) above, and when the switch is used, steps (b) and (c) ) are performed sequentially or simultaneously. When step (c) is over, step (d) can also be carried out automatically immediately afterwards by setting the limit switch, and the next step (e) can optionally be carried out using a detection ultrasound instrument or a detection infrared instrument in a position where it is possible to see through the bar for receiving the stop block to thereby confirm that the stop block has fallen onto the bar for receiving it. When the device for lifting the stop block in step Ce) is in its uppermost position, the limit switch is used, and steps (f) and (g) are carried out according to orders from this limit switch, and when the device for lifting the stop block is in its lowest position , step (h) can be performed.

Each of these steps or operations can in practice be carried out easily by means of an electrical circuit from the respective limit switches and detection instrument to each operating mechanism. In addition, a number of molds can be arranged at the same distance from each other and in parallel on the rectilinear rails or they can be arranged radially on the circular rails, whereby the preheating of the molds, the filling of the molten zinc-based alloy and the cooling etc. can be carried out in sequence, and the mold apparatus according to the invention can be used in the step after cooling, whereby the stop blocks can practically be continuously removed from the moulds.

The mold apparatus used in step 5 of the present method offers several advantages in that it not only greatly contributes to the saving of labor for removing large stop blocks of zinc-based alloy from the molds, but also because it satisfies the requirements for a mass production system for the stop blocks and moreover, because the area used when removing the stop blocks from the molds can be greatly reduced.

For step 5 of the present method to be carried out, if dross is skimmed from the stopped molten zinc-based alloy surface, any of the dross skimming apparatus for stopped metal as described in Japanese Patent No. 31067/70 and in Japanese Patent No. 19<1 >+36/71, used. It is also possible to install a device in a step by step 5 and constructed in such a way that two dros saw foaming plates can be moved to the center from. both end parts of the mold in the longitudinal direction of the mold, and in the middle part of the mold there is arranged a plate comb which is shaped by modeling the skimming plate as an inverted triangle, and the dross is moved and collected outside the mold by means of the plate comb and a plate which closes both end parts of the drogue which is taken up/' ceto triangular plates. In fig. 1 shows the installation position for a device for removing dross. When the stope block is to be cooled quickly after assembly of the drogue, water lines are used which, supported by a suitable machine frame, are arranged above and below the mold and/or the sides of the mold so that they will not be adversely affected during the transport of the mold in the one in fig. 1 indicated position for the mold and the stope block cooling zone, and when the water is drained through and/or a water-sealing cooling is achieved with the help of a number of holes in the water lines, a stope block of 500-1000 kg can be cooled in the course of approx. 20 minutes from the molten state to a temperature of 200-260°C (surface temperature of the stop block), and at this temperature the stop block can be easily removed from the mold. To facilitate the collection of

the above-mentioned dross when the mold is heated for the fourth step is carried out, it is furthermore advantageous to use a preheating method where at least ln combustion flame consisting of air-fuel gas is brought to play on the inner surface of each side wall of the four sides of the mold, the combustion flame being blown towards it lower part from the upper part of each side wall's inner surface. Using this preheating method, it is possible to preheat the ductile stope iron mold with an initial temperature of approx. 20° "ti L <Sil temperature of 160-170°G in the course of 7-8 minutes. In such a pre-

heating, it is also preferred to use a preheating gas burner which is made in such a way that it consists of an essentially straight air line with an air inlet and a fuel gas supply line with a fuel gas inlet which closely overlaps the upper part of the air line, an internal line which .to the nozzle and which is inserted through an outer wall of the air supply line from the outer wall of the Fuel gas supply line so that a gap is obtained between the inner line and the outer wall of the piercing part of the inner line and which is suitable to occupy a separate outer conduit for the nozzle, one end of the outer conduit for the nozzle being attached to the outer wall of the air supply conduit forming a nozzle, and at least one piece is arranged at the longitudinal side of the rectangular air supply conduit and preferably a number of such pieces nozzles are arranged on each of the four sides.

When the above-mentioned preheating step, dross skimming step and forced cooling step, as shown in fig. 1 is used according to the invention and when all steps from the charging of the raw material zinc in the first step to the removal of the stop block in the fifth step, including the transport of the stop block, are fitted into an order or control system provided by means of an electric circuit, can the present invention is carried out with a small number of workers by control from a central control room in connection with any of the above-mentioned step parts used in the present method. It is self-evident that even if the above-mentioned additional steps are not used, it is entirely possible with the help of the electrical circuit to control the process for the continuous production of stopper blocks.

Of the drawings, fig. 1 shows a flowchart for an embodiment of the present method, in fig. 2 a horizontal view of an embodiment of the apparatus used in connection with step 2 of the present method, in fig. 3 and k side view and front view of it in fig. 2 shown apparatus, in fig. 5 a horizontal cross-section of an embodiment of the alloying furnace which is used in connection with step 3 of the present method, in fig. 6 a longitudinal section through the alloy furnace according to fig. 5, on fig. 7 a cross-section taken along the line A-A according to fig. 5, on fig. 8 a cross-section taken along the line B-B according to fig. 5, on fig. 9 a longitudinal cross-section seen from the front of the stirring device which is suitable for use in connection with the alloying furnace according to fig. 5, on fig. 10 the ratio between the mixed raw materials for smelting according to the invention of a zinc-based alloy, and the ratio between the added amount of molten zinc and the time required for melting an aluminum stop block, in fig., 11 a side view of an embodiment of the apparatus used in connection to step h of the present method, in fig. 12 a horizontal view of the apparatus according to fig. 11, on fig. 13 a flowchart for an example of the work mechanism system used in step k- of the present method, on fig. lh a horizontal view of an embodiment of the apparatus used in connection with step 5 of the present method, in fig. 15 a longitudinal cross-section seen from the side and which shows a cross-section through the mold part according to fig. I<1>*, in fig. 16 a cross-section seen from the side and which shows a cross-section through form-

the part according to fig. 1^-, and on fig. 17, 18, 19 and 20 cross sections of the couplings for tipping the mold.

It appears from fig. 1 that this includes each apparatus and alloy furnace for melting, of the zinc-based alloy as shown in fig. 5-8. According to a preferred embodiment in accordance with that in fig. 1 shown flow chart. 6 parts by weight of molten electrolytic zinc are introduced (quality: Cd traces, Pb traces, Fe traces and the rest zinc)

and 10 parts by weight of molten distilled zinc (quality: Cd 0.0<>>+%, Pb 0.20%,

Fe 0.015% and the rest zinc) in the well 33 of the mixing furnace 31. These molten zinc grades were continuously filled in the well 33 from the melting furnace by means of each dipping device with a capacity of 75 kg, 2h kg being transferred at each dipping, and an aluminum stop block ( in piece ø.5 kg) was filled in the molten zinc from well 33 while the molten zinc was stirred (temperature 520°C). The co-

lead added charge was approx. 2.2 t so that it had a content of 0.23% by weight of aluminium. This move was repeated, i.e. the continuous 'determined amount of charging of molten zinc by means of a dipping device, stirring and melting of the aluminum stope block (in pieces of a. 5 kg) which was automatically supplied by means of a timing device in a quantity of 1 stope block per 11 minutes, and metallic lead (0.8 kg/hour) was added and melted so that the molten zinc had a content of 0.2 wt% lead, and the resulting molten zinc-based alloy was sequentially flowed into the muffle furnace.

At the same time as the production of the molten zinc-based alloy, this was taken up by immersion from the well 50 of the muffle furnace 32 with the help of the one in fig. 11-13 showed stopping device in an amount of approx. 11 t/hour, and angular stope blocks with an average weight of 0.92 tQnn were stuffed.

As a form, a form of ductile stope iron was used whose cross-section was approximately concave-straight with a length of approx. 1.6 m. The twelve molds were rotatably placed on the mold transport apparatus of the circular turntable type as shown in fig. 1 (the support mechanism has been omitted as this has been described in detail above). It

molten zinc-based alloy was successively stuffed into the molds which had been heated in advance so that the inner surface of the molds in the one in fig. 1 preheating zone shown received an average temperature of 160°C. After defoaming the dross from the surface of the molten zinc-based alloy after stopping, the various molds and block blocks were also subjected to forced cooling in the mold and block cooling zone, as shown in fig. 1. Then each stope block was

automatically removed by means of the form apparatus for removing the stope block, as shown in fig. lh- 20. After h hours of stopping, a total number of ^-8 stope blocks had been produced.

It was confirmed by the above process that almost a fixed quantity of the molten zinc-based alloy flowed over each time the raw materials were introduced, from the overflow channel in the partition wall in the connecting part between the mixing furnace and the muffle furnace. In addition, to investigate whether the molten zinc-based alloy by overflow flow was supplied to the muffle furnace with the correct content of constituents, an analytical sample was taken from each of the produced ^8 stope blocks and analyzed by means of the atomic absorption method, and the results obtained are reproduced in the table 2 below.

It appears from the results in table 2 that these confirm that stope blocks with the desired composition were obtained essentially continuously with a high production yield and that there was a variation of approx. + 0.01"+% of the aluminum content (0.23%).

Arithmetic mean for the analyzed constituents:

Al 0.235%, Pb 0.203%, Cd 0.035%, Fe 0.0113%.

Claims (5)

1. Procedure for continuous production of zinc-based alloy ingots of large size using an alloy furnace comprising a mixing furnace (31), at least one charging well (33) communicating with the mixing furnace through a side wall thereof, at least one stirring device extending into the mixing furnace, a muffle furnace (32 ) which is in connection (48) with the mixing furnace, at least one discharge well (50) which is in connection (47) with the muffle furnace through a side wall thereof, and a partition wall (37) with an overflow channel (38) and arranged between the mixing furnace and the muffle furnace , whereby a zinc melt is produced, e.g. in a melting furnace (1), after which a selected amount of the molten zinc and at least one alloy metal ingot are introduced into the charging well (33) while stirring the molten zinc and while simultaneously melting the ingot to form in the mixing furnace (31) a molten zinc-based alloy from the molten alloy metal thus formed and the molten zinc, characterized by the combination of the following steps: a) introduction of molten zinc and alloy metal ingots in the charging well is repeated at fixed time intervals and the ingots thus added are melted and the molten alloy metal obtained is mixed with the molten zinc for continuous formation of a molten zinc-based alloy in the mixing furnace, the molten zinc-based alloy being periodically allowed to flow over from the mixing furnace past the partition (37) and into the muffle furnace (32), b) a selected amount of the molten zinc-based alloy is cast periodically and sequentially from the muffle furnace to produce a large ingot of the zinc-based alloy by supplying the molten zinc-based alloy from the discharge well (50) and introducing the molten zinc-based alloy into at least one mold (93), and c) the amount of molten zinc and alloy metal ingot as in- is led into the charging well per unit of time is regulated so that the quantity thereof introduced into the mixing furnace and the quantity of the molten zinc-based alloy discharged from the muffle furnace are kept approximately equal. 2. Method according to claim 1, characterized in that a discharge well (50) is used which is provided with a supply device for molten metal comprising a pump line (106) for molten metal which extends into the discharge well and whose outlet opening (109) for molten metal is arranged on the outside of the discharge well, a trough (100) which is so arranged that it can be swung back and forth and which is provided with one end which is arranged for receiving molten metal from the discharge opening and with another end which forms a mold opening (101) arranged for pouring the molten metal into a mold (93), a first cylinder (102) attached to the trough for raising and lowering the mold opening toward and away from the mold provided with a level detection device ( 91) comprising an electrode (98) which can be placed over the mold, an electromagnet (110) for raising and lowering the electrode, and another cylinder (99) at the upper end of the electromagnet for raising and lowering it, and which r the casting is performed by placing a mold in a predetermined position and by actuating both cylinders in response to the position of the mold to move both the trough and the electrode to their lowest positions where the mold opening is arranged directly above the mold and the electrode extends in the mould, while the supply apparatus for molten metal is simultaneously used and the molten metal is supplied to the trough and thereby to the mold until the molten metal in the mold comes into contact with the end of the electrode, after which the electromagnet is used to move the electrode upwards and the first cylinder is used to move the trough upwards so that casting is interrupted. 3. Method according to claim 1, characterized in that a charging well (33) and a mixing furnace (31) are used which are connected to each other in a gravity-affected, free-flowing condition so that the vertical levels for the liquids in them are the same, and that it is used a discharge well (50) and a muffle furnace (32) which are connected to each other in a gravity-affected, free-flowing relationship so that the vertical levels for the liquids in them are the same, the lower end of the overflow channel (38) in the partition (37) is arranged so that molten zinc-based alloy flows from the mixing furnace into the muffle furnace when the level of molten zinc-based alloy in the mixing furnace is above the lower end, and where the molten zinc-based alloy is caused to flow from the mixing furnace into the muffle furnace when the molten zinc and the alloy metal ingot is added to the charging well. 4. Method according to claim <3>, characterized in that hot, gaseous combustion products are continuously made to flow in the alloy furnace over the muffle furnace and into the mixing furnace to heat the contents therein. 5. Method according to claim 1, characterized in that the molten zinc is introduced into the charging well (33) using at least one melting furnace (1) with the overflow sluice (2) at its side wall for storing molten zinc, and that a selected amount of the molten zinc is removed from the overflow well at fixed time intervals and introduced into the charging well. o 6• Method according to claim 5, characterized in that the introduction of the molten zinc from the melting furnace (1) into the charging well (33) is carried out using the following steps: (1) the level of the upper surface of the molten zinc (18) in the overflow well (2) is kept approximately constant by supplying molten zinc from the melting furnace to the overflow well in a sufficient amount so that molten zinc will flow over from the overflow well, and (2) a dipping device (12) is set in such a smooth swinging motion back and forth that at one end of its movement one end of the dipping device will be immersed to a predetermined depth in the molten zinc in the overflow well so that when it emerges it will take with it a determined amount of the molten zinc, and at at the other end of the dipping device's movement, the thus collected molten zinc in the dipping device will be emptied from the other end of the dipping device into a trough (14) arranged next to the overflow well and which runs over into the charging well. 7. Method according to claim 5, characterized in that a supply device for molten metal arranged next to the overflow well (2) is used and which continuously transfers the molten zinc from the melting furnace (1) to the overflow well (2) and has a sufficient capacity to constantly maintaining the level of the upper surface of the molten zinc in the overflow well.