FI120384B - Method of casting anodes and anode casting apparatus - Google Patents

Description

METHOD FOR MOLDING ANODES AND ANODIC MOLDING EQUIPMENT FIELD OF THE INVENTION

The invention relates to a method as defined in the preamble of claim 1. The invention further relates to an anode casting apparatus as defined in the preamble of claim 7.

BACKGROUND OF THE INVENTION

The invention relates to a process for converting a metal, such as copper, into anode plates, which is carried out after conversion. In the conversion, the product obtained from flame-smelting furnaces containing iron and sulfur in addition to copper and precious metals, iron and sulfur is removed with oxygen-enriched air. The resulting converter copper is led to an anode furnace, where it is further purified to remove sulfur therefrom. Any sulfur remaining in the anode furnace conversion is oxidized to sulfur dioxide by blowing air into the molten metal. Oxygen is then removed from the melt.

In the anode furnace, molten copper is cast in anode casting equipment into anode 1 sheets having a copper content of about 99.5%.

The anode plate typically has a size of about 1m x 1m and a thickness of about 5cm. The anode typically has lifting lugs from which it can be raised and hung upright for electrolysis. Typically, the weight of the anode is from about 300 to about 40 kg. The finished anode plates are then purified by electrolysis to copper cathodes having a 99.99% copper content.

Of the currently known anode casting apparatuses, the most commonly used type is one which comprises a rotary casting table with a plurality of open molds 35 arranged in a circular shape. The casting table is rotated 2 intermittently so that each movement is followed by a stop for a specified period of time.

In the anode casting apparatus, copper is led from the anode furnace 5 along the chutes to the casting machine and further to open molds made of copper. The adherence of molten copper to the molds is prevented by painting the molds in each round with a molding paint or barium sulphate release agent. The molding comprises the following steps: casting, cooling, removal from the mold, lifting into the cooling pool and painting the mold.

After casting, the anodes in the mold are cooled as the casting table rotates so that cooling water is sprayed onto the anode surface. The anode light in the mold cannot be cooled until its surface is sufficiently solid. Immediately after casting, the molten anode in the mold has a temperature of about 1150 SC (melting point is 1084 HC) and must be cooled to 700 to 950 ° C, where it has solidified so that it can be removed from the mold. The anode must be cooled so that it is sufficiently rigid to be lifted from the mold to the cooling pool immersion cooler where the final cooling occurs.

After cooling, the surface of the anode is not uniform in temperature but may exhibit large temperature fluctuations due to the position and condition of the water jet cooling nozzles and the type of insulating layer in the mold 30 and how uniform it is.

The problem is that after cooling, the anode can retain molten areas, so-called. melting points where the anodime stable is molten and has not solidified. When the anode containing melting points 35 is lifted into the cooling pool, the anode can explode, whereby the anode bodies are flung around, posing a significant safety hazard.

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PURPOSE OF THE INVENTION

The object of the invention is to eliminate the above disadvantages.

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In particular, it is an object of the invention to provide a method and anode casting apparatus for detecting melting points at an anode.

It is a further object of the invention to provide a method and anode casting apparatus which enable the safety of a foundry to be improved.

It is a further object of the invention to provide a method and anode casting apparatus which allow the determination of the average temperature of an anode surface of a freshly cooled variable lamp for controlling the cooling.

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SUMMARY OF THE INVENTION

The method of the invention is characterized by what is set forth in claim 1. The anode casting apparatus according to the invention is characterized by what is set forth in claim 7.

In method (a), a molten metal is poured into an open mold in a predetermined amount; b) cooling the molded anode by successive cooling steps in which water is sprayed onto the top surface of the anode; c) removing the solidified anode from the mold; and d) repeating steps a) to c). In the method, the surface temperature of the anode is measured non-contact with a pyrometer.

According to the invention, after the cooling steps, surface temperatures are measured from a plurality of measuring points over the entire surface area of the anode before being removed from the mold. From the measurement values, the maximum temperature of the anode surface is determined to detect the melting point / 'points of the anode. The maximum temperature is compared to a predetermined limit value of 5. At a maximum temperature equal to or greater than a predetermined threshold, the anode is prevented from being removed from the mold. When the maximum temperature is less than a predetermined threshold, the anode is removed from the mold.

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An advantage of the invention is that dangerous melting points can be detected in time to prevent anode explosions, which improves safety.

The anode casting apparatus of the invention includes a feed device for feeding molten metal; a plurality of open molds for receiving the molten metal from the feeder to form the anode; a water jet cooling apparatus for cooling the molded anode with a water-20 jet; a discharge device adapted to remove the earth from the solidified anode mold; and at least one pyrometer for non-contact measurement of the anode surface temperature.

According to the invention, the pyrometer is disposed in the anode transfer direction immediately before the discharge device and is adapted to measure surface temperatures from a plurality of measuring points over the entire surface area of the anode. The apparatus further includes a calculating and control device adapted to determine the maximum temperature of said anode surface from the measured values, compare the maximum temperature to a predetermined limit value, and instruct the discharge device to leave the anode in a mold if the maximum temperature is greater than or equal to and remove the anode from the mold if the maximum temperature is less than a predetermined limit.

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In one embodiment of the method, the predetermined limit value is the melting point temperature of the anode metal.

5 In one embodiment of the method, the average value of the anode surface temperature is determined from the measured values. The average temperature is used as a control variable to control the cooling water volume of the following anode cooling steps, 10

In one embodiment of the method, the point is measured by a scanning point pyrometer, which wipes the measuring point linearly back and forth over the surface of the anode as the anode moves past the stationary pyrometer.

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In one embodiment of the method, a plurality of molds are arranged to rotate a circular path intermittently such that all molds are stopped and moved simultaneously such that the stop periods and the transfer periods alternate, and the anode is molded and removed from the mold during the stop period.

In one embodiment of the method, the anode is prevented from being removed from the mold by allowing the anode to remain in the mold for an additional orbit without cooling it with water jets.

In one embodiment of the anode casting apparatus, the pyrometer is a scanning dot pyrometer.

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In one embodiment of the anode casting apparatus, the pyrometer includes a rotating mirror.

In one embodiment of the anode casting apparatus, the counting-35 and control means are adapted to determine from the measurement values the average temperature 6 of said anode surface and to use the average temperature as a control variable for the water-jet cooling apparatus.

In one embodiment of the anode casting apparatus, the anodiva-5 casting apparatus comprises a rotatable casting table on which the molds are arranged in a circular shape.

LIST OF FIGURES

The invention will now be described in detail with reference to the accompanying drawings, with reference to the accompanying drawing, in which Figure 1 schematically shows a top view of an embodiment of the anode casting apparatus according to the invention, Figure 2 shows section II-n of Figure 1, Figure 3 schematically anode and scanning point pyrometer, Figure 4 is a top plan view of Figure 3, Figure 5 shows the anode surface temperature measured with a scanning point pyrometer as a function of time, and Figure 6 shows a single scan of Figure 5 measurement.

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DETAILED DESCRIPTION OF THE INVENTION

Figures 1 and 2 show an anode casting apparatus including a plurality of open molds 2 in which molten metal, such as copper, is dispensed from the duct of the feeder 1 to form ano-35s 3. The molds 2 are arranged in a horizontal circular shape on a casting table 9 which is rotatable 7 about a vertical axis. The changing table 9 is rotated periodically such that each movement is followed by a stop for a specified period of time.

5 When a molten metal such as copper is cast into mold 2, the temperature of the metal is about 1150 SC. After the anode 3 is molded, it is moved by the casting table 9. a cooling step, which is performed by a cooling apparatus 4. The cooling apparatus 4 is cooled by spraying the anode surface with water jets at several successive stops. On top of the cooling apparatus 4 is a hood 14, which collects and removes vapors generated during cooling. In the cooling apparatus 4, the water jets are sprayed with the upper water cooling apparatus 15 10 placed directly over the anodes and form a full cone jet. The water cooler 10 sprays water at a flow rate of the order of about 20 l / min / m 2.

The cooling apparatus 4 has three power cooling devices 11 in the rotational direction of the pouring table 9, after the upper water cooling devices 10, which perform the power cooling steps with an amount of water which is several times higher than the cooling water.

Preferably, the cooling apparatus 4 has about 3 to 4 power cooling devices 11. The power cooling steps may be initiated as soon as the surface of the anode has been sufficiently cooled to withstand cooling and not to enter the well. It is advantageous to distribute the power-30 cooling to as many power cooling devices 11 as possible, since it is easier and more accurate to control the cooling than in a single location. For a single power cooling device 11, the spraying time may be, for example, about 10 seconds and the first power cooling step 35 takes time to lower the surface temperature of the anode to a temperature where the anode is no longer yellow glowing. It is preferable to effectively lower the temperature of the anode at the very beginning of cooling, since it is much more difficult to extract heat energy from an anode having, for example, about 1000 SC than from an anode having, for example, about 800 SC.

After the power cooling device 11, the other end of the anode is • lifted out of the mold by the push-in pins 15 at the bottom of the mold 2 (see Fig. 2). The extractor 5 grabs the ano-10 di and conducts it for final cooling. When the anode is removed from the mold, its temperature is about 700-95 ° C with an optimum of about 800 ° C.

Once the anode 3 has been removed from the mold 2, the mold advances to the ground-15 bulking step 16, whereby a release agent, such as barium sulphate, typically mixed with water, is painted on the surface of the mold, which dries for some time. The mold 2 is then ready for a new anode casting.

Immediately before the discharge device 5, a scanning point pyrometer 6 with a rotating mirror 8 is provided, which measures surface temperatures from a plurality of measuring points over the entire surface area of the anode. The counting and controlling device 7 determines the maximum temperature of the anode surface from the measured values of the pyrometer 6, Further, the counting and controlling device 7 compares the maximum temperature to a predetermined limit, such as the melting point temperature of the anode metal. The counting and control device 7, 30 instructs the discharge device 5 to leave the anode in the mold 2 if the maximum temperature is greater than or equal to the above limit and to remove the anode from the mold if the maximum temperature is lower than the above limit. In preventing the removal of the anode 3 from the mold 2, the anode is allowed to remain in the mold for an additional orbit, whereby the melting points are lost. However, the anode that makes the extra rotation 9 is then no longer cooled with water jets to prevent the anode from cooling too much.

In addition, the calculation and control device 7 determines the average temperature of the anode surface from the measurement values 5 and uses this average temperature as a control variable for the water jet cooling apparatus 4.

Figures 3 and 4 schematically illustrate 10 scanning point pyrometers 6 which, by means of a rotating prismatic mirror 8, wipes the measuring point linearly back and forth over the surface of the anode 3 as the anode and the mold move past the stationary pyrometer 6.

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Example

The surface of each anode is scanned about 20 to 30 times, depending on the throughput of the mold. The measurement data to be examined is obtained at approximately 1.6 ms intervals. In practice, the calculating and controlling device 7 is, for example, a computer containing a program for calculating average temperatures. The measurement data can be transferred to a computer, for example, as a power message via the EtherCat node.

A pyrometer for temperatures of about 500 to 1300 aC has been selected as the pyrometer for measuring the surface temperature of the anode, so it is blind to temperatures below 500 2 C and does not detect a mold with a lower temperature. Thus, the measurement is at its lower limit when the py-30 rometer measurement point does not point toward the anode. As the anode travels past the pyrometer with a rotating mirror, a curve with a large number of narrow peaks is generated, as shown in Figure 5. The figure shows a surface temperature measurement showing two hot anodes. A closer look at the single peak of the UN-35 reveals that the pyrometer has been able to measure the hot surface of the anode several times in a single sweep. This is illustrated in Figure 6, which shows the measurement results during one scan of the pyrometer.

The measurement data is started to be collected by the computation algorithm for hand-5 when a certain threshold temperature is exceeded. As can be seen in Figure 5, just before the first anode there is a peak which is apparently caused by heat reflection. The bias temperature must be selected so that interference such as image reflection is not interpreted as part of the anode. When the temperature has been sufficiently below the above-mentioned limit temperature, the anode is considered to have passed the pyrometer. In this step, the maximum temperature of the anode surface is determined. The average of the measuring points 15 at each peak is then calculated, after which the average of all peaks, which can already be regarded as an accurate estimate of the temperature of the entire surface of the anode measured, is calculated.

The peaks of the peaks are searched by first filtering the entire measurement period by exponential filtering to equalize the individual peaks. After this, the minimum of the second derivative is searched for one peak at a time and the mean is calculated backwards. Ignore peak points. Note that the exponentially filtered data is only used to find the peaks of the peaks and the averaging itself is performed on the original unfiltered data.

The invention is not limited to the above embodiments only, but many modifications are possible within the scope of the inventive idea defined by the claims.

Claims (11)

1. Method of casting anodes, wherein a) a predetermined amount of molten metal is cast in an open mold, b) the anode molded in the mold is cooled by successive cooling stages, at which water is sprayed onto the top of the anode, c) the solidified anode is removed from the mold, and d) the stages a) - c) are repeated, and at which method the surface temperature of the anode without contact is measured with a pyrometer, characterized in that - after the cooling stages before removal from the molds, the surface temperatures are measured in a number of measuring conditions. points on the entire area of the anode; - from the measurement values, the maximum temperature is determined by the surface of the anode for observing a melting point (s) in the anode; and - the maximum temperature is compared with a predetermined limit value, and where the maximum temperature is equal to or higher than the predetermined limit value, the anode removal from the mold is prevented, and when the maximum temperature is lower than the predetermined limit value, the anode is removed from the mold. 2. A method according to claim 1, characterized in that the predetermined limit value is the temperature of the melting point of the anode metal. Method according to claim 1 or 2, characterized in that the average temperature is determined by the average temperature of the surface of the anode; and the average temperature is used as the control quantity to control the amount of cooling water at the successive cooling stages of the anodes. 4. A method according to any one of claims 1-3, characterized in that on the anode a plurality of surface temperatures are measured with a scanning point pyrometer, which sweeps the measuring point straight ahead and back over the surface of the anode as the anode moves past the on-site pyrometer. Method according to any of claims 1-4, characterized in that several forms are arranged to rotate in a circular path periodically, so that all shapes are stopped and moved simultaneously, so that the stop periods and the movement periods alternate. and the anode is molded into the mold and removed from the mold during the stop period. 6. A method according to claim 5, characterized in that where the removal of the anode from the mold is prevented, the anode is allowed to be in the mold an extra web revolution without being cooled by the water jet. 20 7. Anode molding device, to which: - feed device (1) for feeding molten metal1, - a plurality of open forms (2) for receiving molten metal from the feed device (1) for forming the anode (3), a water spray cooling device (1) 4) for cooling the molded anode with a water jet, 30. removal device (5) adapted to remove the solidified anode from the mold, and - at least one pyrometer (6) for measuring the surface temperature of the anode without contact, characterized in that the pyrometer (6) in the direction of movement of the anode (3) is placed immediately before the removal device (5) and adapted to measure surface temperatures from a plurality of measurement points over the entire area of the anode; that the device includes a calculation and control device (7) which is adapted to determine from the measured values the maximum temperature of the surface of said anode, to compare the maximum temperature with a predetermined limit value, and to the removal device (5) to order to leave the anode in the mold (2), if the maximum temperature is higher or equal to the predetermined limit value, and remove the anode from the mold, if the maximum temperature is lower than the predetermined limit value. 10 8. Device according to claim 7, characterized in that the pyrometer (6) is a scanning point pyrometer. 9. Device according to claim 8, characterized in that the pyrometer (6) includes a rotating mirror (8). Device according to any of claims 6-9, characterized in that the calculation and control device (7) is adapted to determine from the measured values the average temperature of the surface of said anode and to use the average temperature as the control quantity for the water spray cooling device (4). 25 Apparatus according to any of claims 6 to 10, characterized in that the anode molding device includes a rotatable casting table (9), on which the molds (2) are arranged in circular form. 30