DE1533120A1 - Method and device for cleaning copper - Google Patents

Description

DR. EULE DR. BERG DIPL.-ING. STAPF

8 MUNICH 2. HIUBLESTRASSE 2O

Dr. Owl dr Berg Dipl.-Ing. Stapf 8 Munich 2, Hilblestrasse 20

Your sign Umer sign date

VI / be 14 248 -JO. August 1966

Phelps Dodge Corporation, New York, N. Y _0, USA

Method and device for cleaning copper

The invention relates to the cleaning of copper and, more particularly, to the further cleaning of electrolytically refined Copper.

In a general sense, the invention encompasses the process of purifying copper by prolonged copper treatment; in an atmosphere containing hydrogen to substantially reduce the oxides in the copper and, in addition, to reduce appreciable amounts of hydrogen in the

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(0811) 5162081/8? Telegrcimm-Adr .: PATENTEULE Munich Bank: Bayerische Vereinibank Manchen 453100 Postscheck: Munich «5343

Dissolve copper and. a subsequent vacuum treatment of the hydrotreated copper. The main advantages of this new cleaning method over the procedures prior art are the unique complementary effects of prolonged hydrotreatment and to the ζ v / corner vacuum treatment, one having the disadvantages of the other bridged. So far, an extended hydrogen

W act as Oxydreduktions method has not been applied commercially in the copper cleaning because the high solubility of hydrogen in the porosity in the casting of the purified copper caused in copper great difficulties · In this Zusammerteng, when the hydrogen treatment extended enough for the Oxydreduktion substantially is completed before completion of this treatment according to the invention, the subsequent vacuum treatment according to the invention completely removes the dissolved hydrogen, thereby bridging the problem of porosity on the casting. On the other hand, vacuum treatment has hitherto been remarkable. for this purpose, although it can remove essentially such minor impurities as lead, selenium and tellurium from copper, it has not been used economically because of the relative inertia of its cleaning action. In this context, accelerate the movement of the molten copper caused by da;.; rapid escape due to the vacuum treatment of dissolved water

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substance from the hydrogen treatment considerably reduces the cleaning effect. In doing so, the distance of larger and lower impurities from the copper by combining the extended hydrotreatment with expedient vacuum treatment with the vacuum treatment according to the invention with great ease and dme the Disadvantages carried out as a result of these two treatments must be expected when applied separately. Accordingly, the present invention provides a significant improvement in the economics of copper purification, which copper to a greater degree can clean than before and with greater economic efficiency than before.

The general object of the invention is accordingly to provide an improved one Process for copper purification to create. Appropriate The sub-tasks of the invention are the following:

First, a method for using an extended water treatment in the purification of copper without to create the unfavorable creation of porosity in the cleaned copper.

Second, to provide a method of using a vacuum treatment in the cleaning of copper, which none i: oi: ipli; 'iert.e Vorrichtuni "requires, ur: i so the Reinifrun,' -, iJW" i -. "kuiu- increase.

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Third, to create a method for removing oxygen and sulfur from copper, so that a subsequent one further cleaning can be carried out by a vacuum treatment in a device which consists of a. Is material which would be undesirably affected by oxygen and sulfur present in the copper.

Fourth, a method of removing oxygen, sulfur, trapped gases, and metallic contaminants to create from electrolytic cathode copper, at the same time this cathode copper is melted and poured into useful shapes for making products such as wire, sheet metal, strip, foil and tube will.

Finally, to provide a preferred apparatus for carrying out the general purpose of this invention.

An understanding of these various purposes of the invention will be obtained from the accompanying drawings.

Fig. 1 shows a graphical representation of the influences of the amount of oxygen and the temperature on the Amount of penetration of hydrogen into copper.

Figure 2 is a graph showing the variation in solubility of hydrogen in copper with temperature. _n ,, - ,, -: ·. »{; I.

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Fig. 5 is a graph showing the amount of removal of impurities from molten copper at 1000 ° G by hydrogen as a function of time.

Fig. 4- is a graph showing the amount of removal of impurities from molten copper by hydrogen as a function of time.

Fig. 5 is a graphical representation of the variation in Solubility of hydrogen in copper at 1200 ° with pressure.

Fig. 6 and 6a are schematic representations of a simple one Apparatus for carrying out the method according to the invention.

Figure 7 is a schematic representation of a preferred one Apparatus for carrying out the method according to the invention.

Figure B is a schematic representation of a preferred one Vacuum device, which practical structural details of certain parts of this device Time.

Egg; aei understood that using an electrolytic Process purified copper in general as "cathode

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copper ". Cathode copper is usually in the form of plates about 3 square feet and 12.7 mm thick are therefore melted and poured into suitable forms such as cylindrical ingots before they are further used. If further contamination ^ during melting and casting is avoided, the cast copper, which is thus made from untreated cathode copper, is of high quality, but nonetheless contains impurities which, albeit in minor amounts, undesirably affect the processing of copper for a number of applications. These impurities are essentially oxygen, sulfur, entrapped gases and metals such as lead, mercury, tellurium and selenium the main thing from the surface oxidation of the cathode plates w during manufacture and storage. The sulfur comes mainly from inclusions and surface residues of sulfur chemicals from the electrolytic process. The trapped gases from a stir GasasBimilation during elektrolytischeri process during storage and during melting forth _o mebtalischen impurities are mitgerisüen directly from the anode and make Kathodonkupfer impurities and contaminants eic3 eloktrolytitjchen the bath. Hi "is a

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general experience that all of these impurities vary widely.

Improving the quality of cast copper, which is produced by melting and casting cathode copper has therefore been obtained in a number of ways. An atmosphere which oxidizes during the Melting and pouring prevented, and melting vessels and channels, which do not contaminate the copper, are -

of course of prescriptive use to ensure that the impurities in the cast copper do not far exceed the impurities in the cathode copper, As has been pointed out earlier, "When further pollution is thus avoided, the amount is on Impurities in the cast copper are therefore generally and simply reduced by reducing the amount of impurities in the cathode copper. The oxygen content was reduced by such a selection of the cathode copper that everything was rejected which had a serious' Surface oxidation showed “The sulfur content is through Washing the cathode copper with water reduces the Remove residues of liquid sulfur chemicals from surfaces. The contents of oxygen and sulfur are further through cnemical treatment of the cathode copper reduced to remove surface oxides and water-insoluble deposits of sulfur chemicals. These different known pretreatments of the cathode copper

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before melting can serve to increase the amounts of oxygen and sulfur in the cast copper to reduce a very low height, assuming that the cathode copper started with which is of high quality; and under these circumstances, these pretreatments are largely carried out.

If the cathode copper is not of such high quality and, for example, is so heavily oxidized that a selection is not economical and has surface properties that are not fully effective chemical ones Allowing treatment, the removal of oxygen is usually carried out during the melting process. This de-oxygenation during melting is therefore accomplished by one or both of the methods. The first and more extensive method carried out is that of "carbon reduction", for example using carbon powder in contact with the melt. The second procedure is that of the "carbon monoxide reduction" such as, for example, by melting in an atmosphere that creates a contains a high percentage of carbon monoxide. None this deoxidation process is more than partially effective, and thus both of them are generally merely used as a supplement to the pretreatment. ^ process. Melting in an atmosphere containing hydrogen more than or in connection with LohlsEtoffmonoxyd contains is for a great economic hatred

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not found to be favorable, and indeed from what was mentioned earlier Reason that the high solubility of hydrogen in molten copper (carbon monoxide has a very low solubility) causes porosity difficulties in casting, although methods for avoidance this difficulty are suggested. One such method is the use of a vacuum treatment to remove the To promote the reduction effect of the hydrogen, so that only so much hydrogen is present in the molten copper it must be handled as corresponds to oxygen; this process essentially means that all of the hydrogen is present converted into water vapor in the molten copper, and the problem of dissolved hydrogen which causes such porosity in the cast copper does not arise on. It should be seen that the above suggested method for the use of a vacuum treatment to promote the reducing effect of the use of a vacuum treatment in the method according to the invention differs in that in the above proposed method, the vacuum treatment in the main for the Promotion of how the by-product of the reducing effect is developed during the course of the vacuum treatment; in contrast, in the method according to the invention, the vacuum treatment is developed to remove relatively large amounts of to remove dissolved hydrogen and volatile metallic impurities, with the reducing effect and in to a certain extent the removal of the by-product

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lent gases during the course of the extended hydrotreatment Are completed.

From the above list of the methods most frequently used to date to improve the quality of castings Lupfer, which is made by melting and casting cathode copper, it is understandable that none of these processes included gases or metals Removed impurities. Furthermore, it is clear that although removing the oxygen in general both by pretreating the cathode copper before Melting as well as treatment of the melted Copper is carried out, the removal of sulfur is generally only carried out by pretreatment. Furthermore, it should be understood that none of these processes a more than partial removal of oxygen or Sulfur and therefore these processes, even when they are used together, levels of oxygen and sulfur in the cast copper which, although below the contents in the cathode copper lie still fairly reflect these latter levels, i.e. i.e. that the purity of the cast copper, which is produced by the processes used so far, depends somewhat on the purity of the cathode copper, from which it is made and therefore subject to similar variation.

It should also be noted that the removal of

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Trapped gases and metallic impurities are affected, the process of vacuum treatment, though it is well known so far not on an economic scale in the purification of copper has been applied. The main reason for this is that the removal of some of these trapped gases and the metallic contamination by vacuum treatment is a relatively very slow process, which on can only be increased economically with the help of a comparatively carefully crafted system. Included is in particular the removal of metallic impurities from copper by means of a vacuum treatment of the molten copper has not yet been considered economical been deemed feasible.

In a general sense, the method according to the invention comprises treating copper in an atmosphere which Contains hydrogen (such as by preheating and melting copper in an atmosphere containing hydrogen, or preheating copper in an atmosphere containing hydrogen and melting the copper in another atmosphere or preheating copper in another atmosphere and melting the copper in an atmosphere containing hydrogen), subsequent exposure of the molten copper to a high degree reduced gas pressure and subsequent cooling and solidification of the copper. "Preheating" of copper should mean

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that the copper is heated under supervision to a temperature below the melting temperature, so that for example the copper is kept at an elevated temperature, for example 1000 ° C., during an extended period of time, for example 10 minutes. The reasons for the heating are explained below. The main physical principles involved in this procedure are as follows: When copper, like cathode copper, is heated in a hydrogen-containing atmosphere, this atmosphere is formed is otherwise inert, there are three main effects:

1. Hydrogen penetrates the copper and dissolves;

2. Copper oxides in and on the copper are reduced by the hydrogen to copper, forming water vapor will;

3 · Sulfur compounds will be in and on the copper partially at least broken down into gaseous products.

The speeds at which these above three effects take place depend mainly on the 'x' temperature, the hydrogen concentration, the pressure and the contents and concentrations of the copper oxides and sulfur compounds away. Generally speaking, these three effects run roughly in unison above 600 ° C, whereby the reduction of copper oxides and the implementation of the

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Sulfur compositions are complete when the hydrogen has fully entered and the copper has saturatedο accordingly, if, for example, the hatred the copper oxide is concentrated on the surface of the copper, the main part of the oxide reduction has ended, when the hydrogen has penetrated below the surface. With copper like cathode copper this is The rate of penetration is shown in Fig. 1, showing the effects of temperature and oxide content shows this speed. Sulfur compositions show similar behavior, although the situation is more complex.

Fig. 2 shows the variation in hydrogen solubility in copper with temperature. It can be seen that, though Fig. 1 includes a maximum temperature of 1000 °, which is below the melting point of copper, Fig. 2 has a maximum temperature of 1300 ° C, which is above the melting point. The reason for this is that the solubility for molten copper is easily measurable but the rate of penetration is not. It can also be seen from Fig. 2 that the solubility has a sharp rise in the melting point (1083 ° C). A similar transition behavior in speed penetration at the melting point can reasonably be expected with copper, which is free from Oxides and sulfur compounds are present, but when these oxides and compounds are present in appreciable amounts

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their redistribution during melting is the main factor in the transition behavior of the penetration speed. The relevance of these various states shown in FIGS. 1 and 4 can be seen further below.

The copper oxides and sulfur compounds in cathode copper are, as explained earlier, mainly due to the Limited surface area of the cathode plates. This means, when the oxides and sulfur compounds are considered "predominant Contamination "means that the concentration of the predominant contamination in cathode plates varies greatly with the penetration from the surface this plate changes. The rate of penetration of hydrogen into cathode plates below the melting point varies rapidly with time as the surface layers are penetrated. This fact leads to that the removal of the major impurity by the action of hydrogen on a cathode plate at 1000 ° C can be viewed as a function of time, as shown in FIG. 3. Comparatively shows 4 shows a similar course of the removal of the predominant hydrogen contamination from cathode plates above the melting point, provided that that the same initial amount of impurity as in Fig. J is now evenly distributed in the melt and that the same size of the surface is in contact with hydrogen. From Fig. 3 and 4 it can be seen that, although the surface arrangement is favorable,

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in the molten state, the removal of the major impurity by hydrotreatment is considerably slower to at least 95% removal than in the solid state.

From Fig. 5 and M- it can be seen that the complete removal of the predominant impurities can be carried out by a hydrogen treatment either below or above the melting point. Pre-melting hydrogen treatment without such post-melting treatment is particularly useful if, for example, (a) a content of dissolved hydrogen well below the saturation level in the molten state is desired, and (b) the contact time and contact area in the molten state Condition are difficult to monitor. Condition (a) can be obtained when low porosity with minimal vacuum treatment time is more important than substantial removal of volatile contaminants. Condition (b) may be obtained when the i melting establishment of "batch" type is in which a relatively large amount and in a since melted in which, consequently, the portion of the amount which melts first, for a much longer time than the fraction of the quantity which melts last is melted. A hydrogen treatment after the »melting without such a treatment before the melting is particularly useful if, for example (a) the predominant

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impurities are not limited to the surfaces of the unmelted copper, (b) a content of hydrogen is desired which is close to or equal to the saturation level in the molten state and (c) Preheating is more suitably carried out in an atmosphere other than is an atmosphere containing hydrogen.

Condition (a) can be different in copper than in electrolytically cleaned copper. State (b) can exist if a substantial removal of volatile impurities Grv.a.i ..; cht is. State (c) can be included if a preheating oven is available. which can be used for another atmosphere, but not for a hydrogen carrier atmosphere is applicable.

In the case of cathode copper, there is a combination of heating below the melting point and heating above the melting point in the generally the preferred method when substantial volatile impurities are present in the copper and when substantial removal of these volatile impurities is required.

From Fig. 2 it can be seen that at 1200 ° C about four times as much hydrogen is dissolved in the copper as at 1000 ° · the content of dissolved hydrogen in the process in which essentially removes most of the impurities through a combination of heating

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below the melting point and heating above the melting point is completed depends on the length of the two heating periods, provided that the Duration of heating above the melting point is much lower than that required for saturation.

So much for the removal of gas through a vacuum treatment is concerned, the dissolved hydrogen must be removed, and those remaining gases such as water vapor, hydrogen sulfide and sulfur dioxide, which by-products of the Breakdown of the impurities are must also be removed. Escape in this latter context most of these by-product gases which are below the melting point during heating; are formed from the copper as soon as they are formed, since they come mainly from impurities, which are concentrated on the surface. On the other hand, the gases produced as by-products, which during of heating above the melting point are, to some extent, retained in the copper as they come from impurities contained in the body of the melt - generally speaking, the whole is Gas content including the dissolved hydrogen and of the by-product gases in copper, which is treated above the melting point, about four times as large as the gas content of copper which has been treated below the melting point, provided that in each case the same total amount of

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there are impurities.

As to the mechanisms by which gases are removed from molten copper by vacuum treatment , it should be noted that in general the rates of gas removal are determined by factors whose relative importance varies with the corresponding gases. Hydrogen shows little tendency to remain in molten copper in contents above ce «i degree of saturation at beconcL ·: ·, ■: " ■ temperature and gas pressure «I / & s means when copper saturated with hydrogen gas is exposed to a reduced pressure at normal pressure The variation in the degree of saturation of the hydrogen with the gas pressure at a temperature of 1200 ° C is shown in Fig. 5 5 can be seen that the degree of saturation quickly approaches zero when the pressure approaches zero.This behavior of hydrogen dissolved in copper, as far as removal by vacuum treatment is concerned, is in sharp contradiction to the behavior of other gases Some of these other gases, including water vapor and sulfur gases, are eagerly absorbed by molten copper in the absence of hydrogen even at very low pressures and even if they are in contents

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that are above your normal solubility levels. In the presence of hydrogen, however, the viscosity of these gases is considerably reduced, as is the normal solubility of these gases in some cases in the 'i'at. Dissolved hydrogen inhibits the dissolution of other gases in molten copper and makes their removal easier. This ease of removal of other dissolved gases by dissolved hydrogen from molten copper by vacuum treatment indicates that the quantities and types of other dissolved gases in molten copper have an impact on optimal operation for hydrogen treatment Know of sulfur impurities, which contain a relatively large proportion of sulfur gases, that an optimal removal of all the gas can be achieved by a vacuum treatment with the aid of a somewhat higher amount of dissolved hydrogen than is necessary only for the reduction of the copper oxides and the decomposition of the sulfur compounds A particular example was given to show that such considerations were also made, and not to attach particular importance to them, As far as the process of the present invention is concerned, of greater importance is the influence of the dissolved W content hydrogen on the removal of impurities by a vacuum treatment such as lead, tellurium, and iielen, which are relatively unaffected by a hydrogen treatment. This ^ aspect

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of the method according to the invention is explained below.

In the invention, a vacuum treatment comprises subjecting the molten copper to an ambient gas pressure which is considerably below atmospheric pressure for a period of time, such as by enveloping the container in which the copper has melted, with the gas surrounding the melt first being pumped off, as a result of the previous treatment and subsequent continuous pumping of the gas which emerges from the melt as a result of the reduced gas pressure. is \ already pointed vie, is a result of such a vacuum treatment of heated and in \ _t; jasevztof f molten copper rapid removal of hydrogen and with the hydrogen resulting from the removal as iiebenprodukt and other oinge. ^r; chlc3r: e ': en gases ,, Another result of the VAFC is kuumbehandlung having the removal of impurities which onperaturen at Ί molten copper significant vapor pressures; these impurities include such metals as silver, lead, antimony, arsenic, tin, tellurium and selenium.

The removal of gases, especially hydrogen, and the removal of volatile metallic impurities from molten copper through a vacuum treatment both hear of "pressure equilibrium states",

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however, to a different degree. For example, hydrogen is removed to the extent that the pressure on the copper is insufficient to keep the hydrogen in solution in the copper, as determined by the pressure / solubility ratio shown in FIG. For example, if a deep bath of molten copper, saturated with hydrogen at atmospheric pressure, is exposed to a gas pressure corresponding to one millimeter of mercury, hydrogen will escape from the melt to a depth at which the hydrostatic pressure ™ is less than 1 mm of mercury equal to the atmospheric pressure ■, That is, in the case of hydrogen saturated copper, hydrogen escapes from the molten copper in volumes which are approximately 3000 times (at 1200 ^QG and a pressure of 1 mm mercury) the volume of copper at the surface to zero at a barometric depth less 1 mm varied

It should of course be understood that at the onset of the Ausxetens of hydrogen from the molten copper is the exit velocity is largely determined by the pressure in and above the molten copper is formed by the escaping hydrogen itself. As far as the pressure above the melt is concerned, it depends on the speed with which hydrogen is pumped out of the envelope, based on the speed, in which hydrogen emerges from the melt »

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The pressures under the surface of the melt depend in a very complicated way on the effervescence of the exiting hydrogen and on the hydrostatic pressure and pressure above the melt. At a pump power sufficiently iac to hold a gas druck.au over · Jaehmelze which is below atmospheric pressure, the bubbling action of the exiting hydrogen is, of course, in view of the relatively be ¹ large volume of entrapped "is hydrogen extremely hc". '· ■ tig.

Different are the layers of the equalization, which are aas removal of volatile impurities. dominate, of very different order al. ^ £ <, nj _} which the removal of hydrogen and other gases Ιο prevail. For example, has; Lead has a vapor pressure which corresponds to about 10 µm of mercury at 1200 Gra-i, that is to say at plays, if uj.ei in the molten Καρ ·> fer in the Särtdgungsgshalt at atmospheric pressure, the vapor from cerium melt only emerges to a depth of about ½ mm when the pressure above the melt is reduced to the equivalent of 1 mm of mercury, provided, of course, that the bath of molten copper is calm. It should be understood that in a characteristic situation more lead is removed from molten copper in a given time by vacuum treatment if the copper is removed to subject all of the copper to surface pressures than if it is not bf-

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is away. Ira in general, this ease of removal by movement is all volatile: 'Impurities which may be present in the copper can be attributed, although some of these impurities, for example selenium, have much higher vapor pressures than Jilei at temperatures of molten copper and are therefore not significantly affected by the' Depth effect "can be influenced. In this context, the general example is mentioned, which occurs when soda is shaken, and - ■ Although the explanation of the movement effect on the retention of gases and vapors from liquids. This "soda-water effect" is to varying degrees for all vapors and gases released in molten copper

applicable. That is, removing impurities from molten copper by vacuum treatment by moving the copper because of the "" Sodawas: ■ erEffektes " is relieved, even if the pressure on it

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of the impurities are high enough that the aforementioned "depth effect" is not significant. Other phenomenon ^l \ mene as the Vlirkung an impurity on the Previous j pose another are of course also included in removal of an impurity by a vacuum treatment. It is now obvious that the removal of such volatile impurities as tin, lead, arsenic, antimony, tellurium, selenium, and silver from molten copper should be facilitated by a vacuum treatment by the movement of the molten copper,

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which is attributable to the leakage of dissolved hydrogen.

It should be noted that facilitating the removal of volatile contaminants from hydrogen leakage is important in determining an optimal hydrogen content for the molten copper. It means that an optimal preheating and melting process for the copper, which is the hydrogen content as highlighted above is influenced, in part, at least by the requirements for the removal of volatile stocks dividing is determined by a vacuum treatment, even if this removal is not directly through the process is affected. The importance of these and other facts in choosing a preferred device for the implementation of the method according to the invention are explained below.

The method according to the invention can easily be carried out by means which are schematically shown in FIG Figures 6a and 6b are shown. In these two figures it is shown that; hydrogen treatment and vacuum treatment can be performed sequentially in the same device through "Step 1" and "Step 2". In Fig. 6a and 6b is 1 gin of conventional copper smelter from of the "coreless induction furnace" type; 2 is a well-known source of a hydrogen-containing atmosphere, which, for example, by monitored combustion of

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Natural gas is produced, 3 is a conventional vacuum pump, 4, 5 and 6 are valves for optionally switching off the atmosphere source or the vacuum pump, as shown ο It should of course be understood that means for charging and discharging the furnace 1, which are shown in Fig , 6a and 6b are not shown for the sake of clarity, are necessary, and these can most simply be a removable access cover in the enclosure 7, through which soft solid copper can be placed in the furnace 1, a device for tilting the furnace 1, a removable passage in the cladding 7> from which molten copper can be poured and means for creating an inert atmosphere to protect the cast copper from atmospheric oxidation. These latter different devices, which ^{are not shown in S 1} Ig ₀ 6a and 6b, are very well known. The cleaning method for the device according to FIGS sealed and cleaned with a hydrogen carrier atmosphere, which enters through valve 4 and exits through valve 5. The uncleaned copper is then heated and melted while a flow of a hydrogen-containing atmosphere is maintained in the jacket 7. The valves 4 and 5 are then closed, the pump 3 is put into operation and the valve 6 is opened. The pumping takes place for a period of time after which the valve 6 is closed and

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the pump 3 is switched off. The valve 5 is then opened to let the inert atmosphere into the dumbbell 7, the exit cover is removed and the cleaned Copper poured by tilting furnace 1.

Obwciil uie device according to J? Ig. 6a and ob p
and to carry out the procedure according to
iicu-aj.- xsi _{r it} has many i ^ ailments.

Ers''·' ■ = :: ■■ :. , 3-? Hi.ffthe provisions according to FIg. 6ε. · ΧγΛ '< ^7y <kei.no optier.:."-.- use for cL. «Vj ^ erstoiTbehandlu * ;; ii.ch for (" l:.: -' f vacuum treatment ao; ■ :; i'- r a cpbimalri? ^r 'erbal <; ~ nis swi ^ r.hin these two Leaaridlungs according to the o ^i; en us ^ established teachings »

In the first context in particular, the time at which the unpurified copper is heated before it is melted cannot be fully controlled; the surface contact of the copper with the hydrogen-bearing atmosphere
before, during and after melting that is minimal
The depth of the molten copper is maximal and the limitation of the effervescence of the hydrogen is maximal.

Second, the furnace facility is not designed for large pieces of copper such as cathode plates applicable.

Third, the device according to FIGS. 6a and 6b can only work in batches, since the feed »hydrogen

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treatment, vacuum treatment and emptying in sequence carried out so that each prohibits the execution of the other.

Because of the aforementioned disadvantages, some of which are one Decreased cleaning performance and other of them result in an economic disadvantage is the simple device according to FIGS. 6a and 6b not preferred for carrying out the method according to the invention, although this is practical and explains the possibilities for using completely conventional equipment.

A device which does not have any of the compartment parts of the device according to FIG. 6 is shown in FIG. Fig. 7 shows a schematic representation of a preferred device for cleaning copper p-enäi: of the invention, in particular cathodon copper. The performance according to Fir. 7 is created for an adaptable and optimal application of the cleaning method according to: the invention and for continuous work; At the same time, this device achieves maximum performance and economy of manufacture. I: .- The device according to FIG. 7 essentially has a "zone" heating and melting furnace for the hydrogen treatment and a "flow through" vacuum device for the vacuum treatment. The "zones ⁿ -0fen, which is continuously charged with cold cathodes, in turn feeds hydrogen-treated molten copper continuously into the" flow-through "

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Vacuum device, which in turn supplies valcu-untreated, hydrotreated molten copper in a pouring facility for cooling and solidification in useful Supplies molds. It should of course be understood that as far as the oven of Figure 7 is concerned, there is a great variation is well known of "zone" furnaces in metal treatment, which refer to heating methods, either gas or electric Current or a combination of these two and vary in terms of geometric arrangement which either vertically or horizontally or otherwise no can. Accordingly, the Cfen is in Fir .; V is just a typical example of such a "zone" furnace. On the other hand, should As far as the vacuum device in Fig. 7 is concerned, it should be noted that such devices for uie copper cleaning not well known - ^ ine vacuum device which in general: r. »in the facility 21 in i'ig. 7, v. 'Will be detailed later in connection with Fig. 8 described.

Other, generally similar </ & kuumeinrichturigen, which for Zv: ec> e of the present invention are, are at the same time as the present application filed, patent application "Process for vacuum cleaning von Metals "shown and described by the applicant. The additional objects of the device in Fig. 7, that is, the items other than the oven and vacuum device are all conventional and im

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general in various 'J-' techniques including well known in copper cleaning. No detailed explanation of these additional items is attempted, as this would also differ from the main explanation. In connection with these additional Objects should generally be understood that the selection of their particular designs is somewhat arbitrary and is largely a matter of propriety. Such objectives, in which the choice of execution of the various objects of the device in Pig. 7 is preferably prescribed by the invention from the following explanation of the device according to Fig. 7 revocable.

In Fig. 7 further, 20 is a "zone" He + z and smelting furnace, 21 is a "flow vacuum / treatment device, 22 is a pouring device, 25 is a hydrogen atmospheric generator, 24 is an inert atmosphere generator and 2p is a vacuum pump system. In further detail, 26 is a trough which connects the outlet of the furnace 20 to the inlet of the vacuum device 21, 27 is a trough which connects the outlet of the vacuum device 21 to the inlet of the pouring device 22, 28 is a pipe which connects the atmosphere generator to the furnace 20, 29 is a pipe which connects the generator 24 for the inert atmosphere to the channels 26 and 27. 50 is a pipe which connects the pumping system 25 to the vacuum device 21.

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With further reference to? Ig. 7 the copper cathodes 30, after entering the furnace 20 edge to edge one after the other on rollers, are gradually heated as they pass through the furnace 20 to a temperature of approximately 1000.degree. C. in a zone A, at 1000.degree. C. through a are held zone B and v / eventually grounded m the zone C melted ^ ine hydrogen atmosphere y \ from the generator 23 is continuously passed into and through the oven 20 for the exclusion of any other atmosphere and enters the region of the entrance of the cathode 30 from v / o they are burnt or otherwise removed into the container 36 and then through the channel 27 into a casting mold 37 of the casting device 22. The inert atmosphere is continuously conducted into and through the channels 26 and 37, then flows through an inner jacket 39 and an outer jacket 40 of the vacuum device 21 and also enters the lid 41 of the pouring device 22, so that another atmosphere is completely excluded. The molten copper forms a seal between the tube 50 and the space between the outer jacket 40 and the inner jacket 39.

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the continuously on the walls of the tube 50 with the help a water cooling coil 43 condensed. The impurities are solid and can be removed from the walls of tube 50 periodically. The channels 26 and 2? can, as shown, for example, heated by electrical induction coils 44 and 45. The vacuum device 21 can for example be heated by an electrical induction coil 46. Supply heating coils 44, 45 and 26 provide sufficient heat to bridge heat losses and keep the molten copper 52 melted without its temperature was remarkably low. In Fig. 7 is no heater for the oven for clarity 20 shown; these heating devices can, for example, radiate tube furnaces for zones A and B and indirect Induction furnaces for zone Qbe.

With further reference to Fir: 7, which is provided is that the heat supply is sufficient, certainly of course the speed of movement of the cathodes 30 along the furnace 20 the flow rate of the molten Copper 52 through the vacuum device 21. In connection with the speed of movement of the cathode: 50 determine the lengths of zones A, B u: ii C of furnace 20 together the times and temperatures of the hydrogen chandlun.c and thereby eggs. Content of in the. molten copper 52 dissolved Hydrogen when the copper leaves furnace 21 through chute 26. (The amount of hydrogen in the atmosphere from the generator 25 must of course, as assumed., be constant

OO9Ö3O / O242 - 52 -

As this proportion also partially determines the rate of penetration of hydrogen into the cathodes 30. "For example, with particular cathode copper, a feed rate of 0.30 m per hour is equivalent to a production rate of approximately 2721 kg per hour; at this production rate, zone lengths produce in the furnace 20 for zone A of 4.57 m, for zone B 4.57 m and for zone C $ ..05 m approximately one volume of hydrogen (transferred to normal temperature and pressure), which in each volume of copper at one atmosphere is dissolved, which ^c of approximately 40 liters of hydrogen, 40% nitrogen and 20 £; Kohlenstoffrnonoxyd composed Under these circumstances, a lioiniijuncsleistung as far as the removing is viewed from oxygen, obtained from approximately 95> As another example, if the.. Production volume to 5442 kg per hour by doubling the speed of the cathodes and increasing the necessary heat supply to the furnace 20 is doubled, with other conditions remaining unchanged, the content of dissolved! Hydrogen almost halved, but the performance of oxygen removal is only reduced by a few percent. The reason why the cleaning performance of the hydrogen treatment is only reduced to a fraction when the production quantity is doubled is, as mentioned earlier, that the kisser oxide contamination in typical cathode copper is reduced

- 35 009830/0242 ΕΑΰ ε :::: -. L

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1 533.1 2Γ

is limited to the surface of the cathode plates. The above two examples demonstrate the importance of the zoning in furnace 20 and further demonstrate that the dissolved hydrogen content of the molten copper J> 2 exiting furnace 20 can be varied widely without substantially compromising the performance of the hydrogen treatment to influence, as far as the removal of oxygen from the cathode copper is concerned. The content of dissolved hydrogen in the molten copper 32 which leaves the furnace 20 is, as already explained above, of great importance for the vacuum treatment in the vacuum device 21 _o On the one hand, the content of dissolved hydrogen in connection with the production quantity partly determines the capacity which is required of the vacuum pump system 25; the greater the content for a given production quantity, the greater the required Pumpa capacity. For example, at a production rate of 2721 kg per hour, as in the above example, a pumping capacity of approximately

■ χ
226 nr per minute is required of the pump system 25 in order to maintain an average pressure of one tenth of a millimeter of mercury in the vacuum device 21. This estimation of the pumping capacity assumes that the dissolved hydrogen is essentially completely removed from the molten copper when it flows through the vacuum device 21 at a rate of 2721 kg per hour, and therefore it is also

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exposed to the hydrogen leaving the copper fast enough to permit removal during passage through the Complete vacuum device 21. The flow rate of hydrogen from the molten copper, when it flows through the vacuum device 21 is in part due to the size and geometry of the interior surfaces the vacuum device 21 and through the otrömungsbild of the molten copper is determined over these areas. It it can therefore be seen that, when actually carried out, not only the pumping capacity of the pump system 25, but also also the size and geometry of the interior surfaces of the vacuum device 21 and the flow pattern of the molten copper over these areas on the content of dissolved Hydrogen and must be related to the rate of production. On the other hand, determines the content of dissolved Hydrogen in relation to all other factors mentioned above the degree and duration of the effervescence, which are attributable to the leakage of hydrogen from the molten copper in the vacuum device 21 and partly determines the cleaning performance of the vacuum treatment, insofar as the removal of volatile ' Impurities is affected. In the event that extensive removal of volatile impurities is required it is an advantage to have a large amount of dissolved hydrogen in the molten copper 32 Having to leave the oven 20 even though, as noted above, the effectiveness of water removal

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hydrogen is not noticeably affected.

The apparatus of FIG. 7 is operated as follows, provided that the furnace 20 empty and switched off, the hydrogen atmosphere generator 23 switched off, the generator of the inert atmosphere 24- switched off, the vacuum pump 2S switched off, the container 55 is empty and the container 56 is empty entirely with solid copper, 'what is filled:

1. The generator 24 is turned on and the; ran :: e device with an inert atmosphere gc. ^- :: ü_t;

2. The generator 2 ~~ is turned on, the furnace 20 with a hydrogen atmosphere (the pressure of the hydrogen atmosphere being sufficient to prevent the inert atmosphere from entering the furnace 20 through the channel 26) and a current filled in hydrogen through the furnace 20;

3 · The heating devices 44-, 4; unc ~ <are aiv-e :: rellt, and the groove 2c · and 27 and the Vakuur.behanclunrseinrichtung 21 Arbeitetoi-temperature (about 1 '' 2FO ^u C) - ebracht ~. (When the vacuum;: andlur ..; ceinrichtunr 21 reaches the working temperature, the copper in the container 36 will be melted no, and the container yc will be almost full of molten copper);

4. The furnace 20 is put into operation and on

009830/0242 -36-

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153312C

brought temperature;

5. The movement of the cathodes JO is started;

6. When the container 33 is almost completely melted Copper is filled, the vacuum pump 25 is switched on (it should be noted that the capacity of the container 33 the capacity of the annular Column 34- exceeds by an amount, v / elcher is sufficient to create a seal after the container 33 partially in the annular Gap 34- is emptied).

From the foregoing it will be understood that a large number of factors affect the optimal use of the design of the device acts as in FIG. 7. Here it is also understandable that a device as in Fig. 7 when optimal for cleaning copper to a certain degree with maximum economy used, can also be used for cleaning copper to a different degree, however with less than maximum profitability. For example, if the oven 20 is the vacuum device 21 and the pump system 25 optimally in connection with a certain production speed is used will, for essentially complete removal of the oxygen, but incomplete removal of the volatile ones Impurities, is a more complete removal

~ 37 -009830/0242

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of volatile impurities can be achieved, as pointed out above, by reducing the production rate. This adaptability in the use of the device is of course a valuable feature as opposed to it for a number of applications the presence of a certain level of volatile impurities in which purified copper is not significant, for a few applications such residual contamination is undesirable is.

Fig. 8 shows the structural details of a vacuum device, which is similar in general sense to device 20 in FIG. The purpose of Fig. 8 and the The following description of the device shown in Fig. 8 is merely that of some practical one To highlight features of a vacuum device which are useful for the present invention, wherein such features are generally not as well known as, for example, features of useful furnace equipment are.

Referring to Figs. 7 and 8, it should be noted that the Inlet chute 123 and exit chute 124 of FIG. 8 the back 26 or 2? corresponding to FIG. 7 and that the vacuum system connecting pipe 147 according to FIG. 8 the Corresponds to tube 50 of Figure 7; other equivalents and similarities between the device 20 according to FIG. 7 and the device according to FIG. b will be discussed later

009830/0242

In Figo ο the main objects of the device are blocks 120, 121 and 122, which have a vacuum treatment chamber V, channels 123 and 124, which lead molten copper into and out of the chamber V, a vacuum line 125, which the vacuum pump system (not shown) with The chamber V connects an insulating jacket 126 and an insulating block 127> which reduce the heat loss from the chamber V, an induction heating coil 129 which heats the chamber V and a support plate 130 »which forms the bottom for the chamber V. In further detail of the chamber V, 131 is an input container which is formed between the blocks 120 and 121, 132 is an output container which is formed between the blocks 120 and 121, 133 is an output borehole which the container 132 with the inside 124 connects, 134 is an inlet channel, which connects the channel 123 with the kingang container 13I, 135 is one of the twelve feed bores, which are evenly arranged on a circle and connect the inlet container 13I to the contact surface 136. 137 is a Ausgangszuführbohrung which connects the contact surface 136 with the output reservoir 132, 138 is a lower seal ring, which has a vacuum-tight seal between the blocks 121 and 122 manages, 139 is an upper Bxchtungsring which a vacuum-tight seal between äem block 122 and the vacuum line 123 creates, 1p2 is an annular trough in the surface 136 for draining a sump; ge

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molten copper, 153 is a circular trough in the contact surface 13ü for guiding molten Copper, which is located above the sump in the trough 152 in the Feed hole 137 flows, and 15? is an annular Recess for distributing the flow from the feed bores 135 on the periphery of the surface 136. In further Detail of the channels 123 and 124, which are structurally identical, 140 is a feed pipe, which leading to molten copper, 141 is a resistive heating element for heating the supply pipe 140, and and 153 are heat insulating pipes which prevent heat loss from element 141 and tube 140. In further detail of the casings 12ü are 14ü and 149 Inlet and outlet tubes, respectively, for maintaining an inert gas atmosphere in the enclosure 148 and in the supply tubes 123 and 124. In further detail of the vacuum line 125, 145 is a removable cover for access, to remove condensed contaminants, 146 is a water cooling hose to create a cooled surface on the Inside of the line 125 for condensation of the condensable To create impurities which will evaporate from the molten copper when it is over surface 136 flows, and 147 is one of the two pipes which connects the vacuum line 125 to two identical vacuum pump systems. These two vacuum pump systems, which are not shown in Fig. 8 for the sake of clarity, are entirely conventional in major detail, and each has, for example, a combination of mechanical

009830/0242 - 40 -

shear pumps, which in the pressure range between 20 and 100 riikron of mercury work sufficiently.

It can be seen that the design of the vacuum contact chamber V according to FIG. that the general working principles of the device according to Pig. fa and the device 21 according to FIG. 7 are identical; ie molten copper is fed to and removed from the contact surface by gravity in connection with the barometric effect. This barometric effect is of course the difference between the approximate atmospheric pressure, which acts on the surface of the molten copper in the containers, and the vacuum pressure, which is generally less than 1 mm of mercury, and on the copper at the upper end of the feed bores ( Fig. 8) or the feed column (FIg ₅ ?) Acts, is to be attributed. Accordingly, the vertical slopes of the feed bores 1J5 and 137 according to i'ig »& and the corresponding feed gaps of the device 20 according to FIG. 7 are such that the barometric columns of molten copper are maintained between the containers and the contact surface, and are so dal: in any case an increase in the level of molten copper in the fixed-passage container, as if molten copper was supplied from the singing channel, a flow of

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molten copper is generated over the surface into the exit chute. The height of a barometric column of molten copper, which corresponds to the atmospheric pressure is about 1193 mm, and so for example it is understood that a vertical height of the supply bores 135 ^u l ^p ig NCL according 137th 8 of 1546 mm allows an overflow from the output container if the container 132 contains molten copper of a height of approximately 153 mm and further that molten copper from the input container 131 through the supply bores 135 via the contact surface 136 * through the supply bore E 137 »i ⁿ the container 152 through the bore 133 and into the channel 124 as long flows, as the depth of molten copper into the vessel 13I, the depth in the container 132 to about 153 mm surpasses. In £ 'ig. δ the blocks 120, 121 and 122, which form the chamber V, are composed of compact graphite. Another material for the blocks 120, 121 and 122 is a compacted, difficult to melt oxide material, but the heating cannot be carried out by induction, and the induction coil 129 is therefore replaced by molybdenum or other suitable resistance heating elements, which are placed between the dumbbell 126 and the chamber V are arranged. It should be noted that the inert atmosphere contained in the casing 12 serves the purpose of protecting both the molten copper and the hot graphite from attack by the atmosphere and also the inevitable small amount of inertia eu as the

009830/0242 "' ^ώ ~

Enclosure 12b to make the interior of the chamber V largely harmless, which prevents the penetration behind the sealing rings 138 ^{and <} i 139 and. attributable to the permeability of blocks 120, 121 and 122. It can be seen that on the. Block 122 could be omitted if block 121 extends upwardly so that it is itself in contact with vacuum line 125. Here, the provision of the block 122 is in Pig. 8 merely to show how a substantial depth of the chamber V above the contact surface 136 can be economically carried out in order to create a sufficient depth of the heated surface above the contact surface 136 to accommodate the effects of the rather violent agitation of the molten copper, which result from the removal of hydrogen from the molten copper and which, as previously discussed, aids in the removal of volatile impurities. In this latter context, it should be noted that the contact surface 136 in Figure 8 is substantially horizontal; in contrast, the contact surface of the device 20 in FIG. 7 is essentially vertical. In general, a horizontal contact surface is preferred if extensive removal of volatile impurities is required at certain passage speeds, while a vertical contact surface must be preferred if only partial removal of volatile impurities is required, but with high passage speeds ^^ inoi ^ Vreitc ^ is called * The reasons for these rather different abilities

J ü

These two special forms of contact are mainly due to the different ones Arrangements of the two contact surfaces in relation to the cooled surfaces on which the volatile impurities condense and in the different ones Effects of gravity causing the molten copper to flow over the two interfaces. It should be understood, however, that despite these differences, which are quite different optimal applications for prescribe these two configurations of the contact surface by cleverly determining the content of dissolved hydrogen, the pumping capacity of the vacuum system and the flow rate of the molten copper such as explained earlier, both surfaces provide high cleaning performance over a wide range of impurity levels and over a wide range of requirements for a removal of the impurities can achieve. It should be understood that the training of the. Vacuum treatment equipment for use in an apparatus such as the apparatus of FIG. 7 is not critical where 'the purpose of the present invention is mainly through appropriate monitoring of operational parameters such as the nature and duration of the hydrogen treatment, the pumping capacity of the vacuum system and the production volume is carried out expediently, as explained earlier. It should furthermore and finally be understood that a wide variety of general types of

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direction which is of the type shown in Fig. 6 for Batch work on the one hand up to the one shown in ^ ig · 7 Continuous working type, on the other hand, can be applied to copper according to the invention clean, and that this diversity, the types of devices in each case essentially associated facilities for simultaneous hydrotreatment and Having vacuum treatment of copper.

009830/0 2 42

Claims (1)

Claims A method of purifying copper characterized by melting copper in an atmosphere containing hydrogen, maintaining the molten copper in the atmosphere until the copper contains substantially no copper oxide and until the copper contains dissolved hydrogen, and then exposing the molten copper to a gas pressure, i WEL more, compared with the atmospheric pressure is reduced. 2. A method for cleaning copper, characterized by preheating and melting copper in one An atmosphere containing hydrogen and then subjecting the molten copper to gas pressure, which is very reduced compared to atmospheric pressure. I 5 «Process for cleaning copper, marked by heating and melting copper in a hydrogen-containing atmosphere to substantially to remove the oxygen from the copper and to dissolve hydrogen in the copper, and subsequent Subjecting the molten copper to a gas pressure which is very high compared to atmospheric pressure is reduced to remove the dissolved hydrogen from the 009830/0242
i remove molten copper. 4. Process for cleaning copper, marked by heating the copper in an atmosphere containing hydrogen to a temperature below the melting point of the copper, subsequent ochmelting of the heated copper and subsequent Subjecting the molten copper to gas pressures which are greatly reduced compared to atmospheric pressure are. 5. A method for cleaning copper, characterized in that that the copper is heated in a hydrogen-containing atmosphere for a period of time which is sufficient is to convert the oxides in the copper by the hydrogen with the subsequent development of water vapor in the to reduce substantially and is sufficient to use excess hydrogen for the reduction of the Oxides to dissolve the required amount in the copper, and that the heated copper is melted and then a gas pressure that is greatly reduced compared to atmospheric pressure is exposed. G. A method for purifying copper, characterized by heating the copper in a hydrogen containing one Atmosphere to a temperature below the melting point of the copper, subsequent melting of the heated copper in an inert atmosphere and 0C9CS0 / 0242 15331 finally exposing the molten copper to a gas pressure which, compared to atmospheric pressure, is very reduced. 7. The method according to claim 1, characterized in that that the copper is electrolytically refined copper. β. Method according to claim 2, characterized in that that the copper is electrolytically refined copper. 9. The method according to claim 4, characterized in that that the copper is electrolytically refined copper. 10 · Procedures for removing metallic contaminants of copper, characterized in that substantial amounts of hydrogen are dissolved in the copper in order to to cause substantial movement of the copper while it is subjected to a gas pressure which, compared “It is very reduced to atmospheric pressure, and that the copper is kept molten. 11. Process for removing oxygen and sulfur made of copper, characterized by preheating the copper in an atmosphere containing hydrogen, for a period of time which is sufficient to the - 48 - 009830/0 2 42 Oxygen in the copper largely through the hydrogen with subsequent development of water vapor and to reduce hydrogen in excess of that required for the reduction of the oxides To dissolve henge in the copper, melt the copper and then subject the copper to gas pressure, which is very reduced compared to atmospheric pressure. 12. The method according to claim 10, characterized in that the copper is electrolytically refined copper. 15. The method according to claim 11, characterized in that that the copper is electrolytically refined copper. Device for cleaning copper, characterized by a furnace device for melting the copper in an atmosphere containing hydrogen, means for generating the atmosphere, which Contains hydrogen, a vacuum system, a device for pumping the molten copper into the Vacuum system, a device for circulating the molten copper through the vacuum system, a device that keeps the molten copper in the Vacuum system keeps molten, a pumping device for keeping one relative to atmospheric pressure very low pressure in the vacuum system, a device for conveying the molten copper - 49 - 009830/0242 the vacuum system and a device for cooling and solidifying the molten copper. 15 «, device according to claim 14, characterized in that that the furnace means is a zone furnace in which copper is progressively heated and ultimately melted will" 16. The device according to claim 14, characterized in that that the means for conveying the molten copper in and out of the vacuum system partially off one piece with the device for circulating the molten copper through the vacuum system. 17o device according to claim 14, characterized in that that the means for conveying the molten copper into and out of the vacuum system includes means to expose the copper only to an inert atmosphere during the transport process. 18. Device according to claim 14, characterized in that that the facilities for the circulation of the molten copper through the vacuum system containment facilities at the inlet of the vacuum system and container devices at the outlet of the vacuum system. 19 »Device for cleaning copper, marked by a furnace device for the preheating of 009830/0242 153312b Copper in an atmosphere containing hydrogen, a device for generating the Y / ascarbon atmosphere, a device for melting dec heated Copper, a vacuum system, a device for conveying the copper into the vacuum system, a Device for the circulation of the molten copper through the vacuum system, a line for conveying of the molten copper from the vacuum system, a pumping device for keeping one in comparison to atmospheric low pressure in the vacuum system, a heater for holding the copper in a molten state in the vacuum system and a device for cooling and solidifying of the discharged molten copper. 20 · Device according to claim 19 »characterized in that that they have a device for creating an inert atmosphere and also a device for the Melting the heated copper in "an inert atmosphere. 21. The device according to claim 20, characterized in that the means for conveying a device for Protecting the molten copper from atmospheric contamination while it is being transported and in that the means for cooling and solidifying include means for protecting the molten copper has atmospheric pollution during cooling and solidification. 0098 30/0242