Abstract:
An electrode stiffening device that avoids the occurrence of short-circuits produced between anodes and cathodes during electrodepositing processes, wherein said device comprises a rigid monolithic body of side inclined walls configuring a triangular-shaped cross-section that is wider in its rear portion, where said side inclined walls join in the front portion of the device, forming a fit area arranged to receive the peripheral edge of an electrode tightly, preferably of an anode and making it stiff in its whole extension and separating it from the adjacent electrodes.

Description:
[0001]    This application refers to an anode straightening, separating and stiffening system, including at least a stiffening device, preferably plastic, that improves the quality and increases the production of metallic cathodes obtained from electrolytic processes, thus avoiding the short-circuits that influence on the formation of nodulations on the cathode surface. In addition, said system and device installed along the sides of each anode increases the efficiency of the electric current and extends the time of use of anodes, thus settling part of the issues existing in the electrolytic processes. 
       BACKGROUND OF THE INVENTION 
       [0002]    It is known that during the electrolytic processes to produce metallic cathodes, for example by electrolytic refining and electro-winning, anode plates are used, which are initially flat, straight or vertical. Said anodes, mainly manufactured in lead or in any other proper material for the process, undergo degradation due to the corrosive action of the hot acid electrolyte where they are immersed. In this context, during the operation of an electrolytic cell, the anodes oxidize, with the anode becoming thinner from the gradual release of the oxide formed on its surface. Then, by losing thickness, the properties of the anodic plates change, such as their mechanic properties, being liable to strain, for example concave buckling, losing its original verticality. 
         [0003]    The anode strain results in an inefficient operation thereof, because a strained anode tends to reduce its separation, or simply to join to one or both adjacent cathodes. Said separation or contact reduction facilitates the production of short-circuits in the cathodes to be harvested, which give rise to nodules, malformations or “grains”, thus resulting in losses in the production of cathodes due to nodulation and efficiency loss of the current. 
         [0004]    In addition, once the degradation and straining conditions of the anode occur, corrosion increases and also the plate thinning. This produces greater strains and an even greater loss in the production of cathodes and the efficiency of current. This degradation process of the anode results in the corners of the anode plates beginning to bend even more—due to their thinning—until the change of the anode plate or plates affected becomes necessary. 
         [0005]    In this context, the anodes currently used in the electric refining or electro-winning processes become corroded, thinned and strained due to use and corrosion from the hot acid electrolyte, thus losing verticality and, as a consequence, generating micro-circuits due to the approaching thereof to one or both adjacent cathodes. This result in nodulations or grains in the electrodeposited plates, with the current losing efficiency and the plates harvested being rejected due to nodulation, added to the fact that anode degradation enhances with greater use. Many times this forces to the early replacement of the anode or group of anodes affected. 
         [0006]    In this context, several solutions have tried to improve the properties of the anode in order to reduce the effects the electrolytic means has on said component. Then, anodes have been designed with titanium alloys or other materials that—although increasing the useful lives thereof—make their use much more expensive. Therefore, a solution is required allowing to increasing the anode&#39;s useful life, no matter its composition, while reducing the effects from its degradation on the production and quality of cathodes. 
         [0007]    In this respect, there are methods destined to stiffen new anodes, such as that described in the application for the patent of invention CL 778-1996. Said application describes a method where, through big-sized machines such as hydraulic presses, figures are stamped by a great mechanic pressure applied on the whole surface of the anode, printing several patterns in the plates that make them stiff. Then, when said plates come into operation, they remain stiff for a longer period of time than a plate without being stamped, thus being the issue stated above partially settled. A great disadvantage, however, of the solution proposed by the application CL 778-1996 is that, once corrosion of one or both anodes starts, they lose thickness, with the strain or buckling of them being inevitable and the problems already stated being triggered, i.e., cathodes of poor quality being produced, efficiency of current lost and, consequently, the corresponding rejection of cathodes due to nodulation. 
         [0008]    Another kind of solutions being found in the state of the art corresponds to huge systems of the size of the electrolytic cell, where said systems separate the anodes from cathodes in an equidistant way, using gutter-shaped guides for the anodes and cathodes to displace vertically. Said guiding devices—applied when the mother cathodes do not use edge strips, operate well when the anodes and cathodes are perfectly vertical, i.e. when they are new. However, when anodes start to be used, they begin to become corrode, to lose thickness and to become strained as already stated, with the same occurring in mother cathodes. Then, when the removal of strained anodes and/or cathodes is required, the displacement guides turn into an obstacle making the operation inefficient, because the strain of electrodes due to their use hinders the slipping thereof along said guides. The disadvantages of this system, therefore, are their high cost of implementation, added to the guiding channels not straightening or stiffening the anodes when they become strained. In this context, a solution is required that out of giving stiffness to anodes, allows that both cathodes and anodes can be removed and introduced into the cell without interruptions. 
         [0009]    In addition, in several documents, such as in patents U.S. Pat. No. 5,762,776, CL 46009, U.S. Pat. No. 4,619,751 and U.S. Pat. No. 3,997,421, separating and/or isolating devices are described located on the surface of the anode, both in the lower third thereof, on its sides, in the central part or in a combination of the previous positions, thus allowing to keeping a specific separation between anodes and cathodes, reducing both the risk of short-circuits and the loss of current efficiency. Said devices are installed in the anodes, so that to provide contact and sliding surfaces keeping a uniform distance between the adjacent anodes and cathodes, out of facilitating the introduction and removal of electrodes during the common operations performed in the electrolytic systems. However, when corrosion, and the resulting thinning and strain of anodes begin, said devices only allow to mitigating the effects of buckling, i.e. without making the anodes stiff; therefore, short-circuits equally produce when the anodes degrade and, consequently, strain. 
         [0010]    As derived from the above, in order to reduce strain, increase the quality and production of cathodes, with them being free of nodulations, as well as to increase the efficiency of the current and increase the useful life of the anode, keeping anodes vertical is necessary, as well as ensuring the maximum distance between the anode and the cathode along its full length. However, the traditional separation systems do not consider how to avoid the buckling of anodes in an integral form, only limiting to mitigate the buckling effects with the use of separators as a secondary objective. An example of the above is that the percentage of rejections of cathodes electro won with these systems of separation is within a range of 4 to 7%, which are undesirable factors for the high rates of production managed at present. 
         [0011]    Therefore, the main problem solved by this invention is to straight and stiff anodes by keeping them vertical, avoiding buckling and, also, being able to keep the greatest distance between the anode and the cathode along the full length in an equidistant way, with the percentage of rejections due to nodulations being reduced to 1 and 2% and, therefore, improving the quality and production of cathodes. 
       BRIEF DESCRIPTION OF THE INVENTION 
       [0012]    As already stated, the devices known in the art do not allow to solving the problems from the strain of the anodic plates integrally, i.e. keeping the anodes stiff and totally vertical, while an equidistant separation between them and the cathodes exists, thus avoiding short-circuits and the formation of nodulations that affect the quality and production of electro-won electrodes. 
         [0013]    To address this issue, the present invention proposes a system and a device to straighten and stiffen during its use, while keeping the separation thereof with respect to the adjacent cathodes, thus avoiding the short-circuits that cause the nodulations. This system consists in implementing at least a stiffening device, made up by a stiff, elongated, monolithic body, preferably plastic, installed along a great portion of the peripheral edges of an electrode, preferably along the side walls of the anodic plates, where said device has an inner rectangular section that produces a tight fit to the thickness of the anodic plate in most length thereof, at least above 50% on its greater side, allowing to straightening and stiffening said plate. In addition, the external shape of the invention&#39;s device—that mainly consists in two inclined planes forming a “V”—out of giving stiffness to the anode allows to efficiently separating the anode from the cathode, avoiding the micro-shortcircuits totally, i.e. separating and stiffening at the same time the anodic plates. In addition, the device has other characteristics that favor electrodepositing, as well as facilitating the operation of electrodes during their use. 
         [0014]    As a result from these characteristics, the stiffening system and device of the invention allows to solving the issues of the prior art thanks to the reduction of the micro-shortcircuits generated by nodulations, having an influence on an increased efficiency of the electrolytic cells of at least 2%, this making it possible the production of more high quality cathodes, without nodulations. 
         [0015]    The most important advantage of the invention, as compared with the state of the art, is that the characteristics of the system and device cause the increase of production and quality of the cathodes harvested by 3% to 5%, as well as an increase in the efficiency of current of at least 2%, added to the extension of the useful life of anodes by at least 20%, which are factors with high incidence on electrodepositing. 
     
    
     
       BRIEF DESCRIPTION OF FIGURES 
         [0016]    For a better explanation of the invention, a description will be provided for a preferred embodiment with respect to figures, where: 
           [0017]      FIG. 1  shows an isometric view of a preferred embodiment of the invention&#39;s stiffening system. 
           [0018]      FIGS. 2 a , 2 b  and 2 c    show a preferred embodiment of the stiffening device by deploying on a plane the rear, front and side projections, respectively. 
           [0019]      FIGS. 3 and 3   b  show an isometric view of the cross-section of the stiffening device according to a preferred embodiment of the invention, along with a cut-away drawing of the cross-section of said device, respectively. 
           [0020]      FIG. 4  shows an isometric view of a set of anodes of a cell having the invention&#39;s stiffening system installed according to a preferred embodiment. 
           [0021]      FIG. 5  shows a scheme of a cut-away drawing of the way the stiffening device operates with respect to the separation between anodes and cathodes. 
           [0022]      FIG. 6  shows an isometric view of the inclined planes present on the ends of the stiffening device according to an embodiment thereof. 
           [0023]      FIGS. 7 a  and 7 b    show an isometric view of an embodiment of the stiffening device of the invention along with a cut-away drawing of the cross-section of said device, respectively. 
           [0024]      FIGS. 8 a  and 8 b    show a plan view and side projection, respectively, of an embodiment of the invention, where the stiffening device incorporates anode-separating elements. 
           [0025]      FIGS. 9 a  and 9 b    show an isometric view of the rear projection, respectively, of a stiffening system with the device of  FIG. 8  in a set of anodes. 
           [0026]      FIG. 10  shows an isometric view of an embodiment of the invention&#39;s stiffening system including at least a ring-type central separating device along with a stiffening device. 
           [0027]      FIGS. 11 a , 11 b  and 11 c    show rear, front and side views, respectively, of an embodiment of the invention&#39;s stiffening device. 
           [0028]      FIGS. 12 a  and 12 b    show an isometric view of an embodiment of the invention&#39;s stiffening device along with a cross-section, respectively, that includes reinforcement in the fit area with the anode. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0029]    The present invention consists in a stiffening device and its incorporation to a stiffening system allowing to stiffening and keeping an anodic plate straight in its whole extension, while allowing keeping equidistant separation along the whole anode with respect to adjacent cathodes. Said system and device allows to reducing the formation of nodulations in the electric cathodes deposited by avoiding the formation of short-circuits originating in the reduces separation between anode and cathode, in addition to increasing the useful life of anodes by preventing their strain from the on-going degradation they are subject to during the operation in the electrolytic means. 
         [0030]      FIG. 1  shows an embodiment of the stiffening system incorporating stiffening devices  2 , two in particular, installed on the side  5  of an anodic plate  1  along most of the extension of said sides  5 , covering at least 50% of the extension of said side or preferably between 50 and 100% of said sides, where in an embodiment the whole extension of the greater side of the electrode is covered. In a preferred embodiment of the invention, said stiffening devices  2  include inclined planes  3 , as detailed in  FIG. 6 , located on at least one of the edges of the stiffening device  2  over the side walls or planes  4  of said device. Said inclined planes  3  facilitate the operation with the electrodes by allowing the proper location of them thanks to the sliding occurring between the edges of an electrode and said inclined planes  3  during the removal or entering to the electrolytic cell. In this respect, out of facilitating the right location of the electrode in the cell, the inclined planes prevent them to get in contact during said operations and, therefore, to become damaged from said contact. In a preferred embodiment of the invention, the stiffening devices  2  have inclined planes  3  in both sides of the upper end and in both sides of the lower end of said device, as shown in  FIG. 1 , thus facilitating that the electrodes may freely slide over said planes both in the removal and the entering of cathodes and/or anodes of the electrolytic cell. 
         [0031]    In  FIGS. 2 a , 2 b  and 2 c   , a stiffening device can be seen according to a preferred embodiment of the invention, where said device has inclined planes  3  in both ends of the device  2 . In addition,  FIGS. 2 a , 2 b  and 2 c   , showing the rear, front and side view of the stiffening device respectively, allow to evidencing its triangular configuration, with the rear portion being wider than the front portion. On the other hand, said figure exposes the fastening holes  6  located in the front end of the stiffening device  2  along the extension thereof. Said fastening holes  6  allow to firmly fastening the stiffening device  2  to the side  5  of anode  1  using fastening means that are not shown in the figure. 
         [0032]      FIGS. 3 a  and 3 b    show schematic views allowing to seeing the configuration of the stiffening device  2  in further detail. In this context, it can be noted that said device has inclined side walls under the shape of “V” defining an equidistant angle with respect to the cross-symmetry axis of the stiffening device  2  and describing a triangular configuration as shown in  FIG. 3 b   . In this respect, the side inclined walls  4  define that the stiffening device  2  has a triangular cross-section with the rear portion being wider than the front portion and where said section, in particular the rear portion, is in charge of keeping the proper separation between anodes and cathodes. On the other hand, the inclined side walls  4  join in the front center of the stiffening device  2  in order to form a fit area  7  with a square or rectangular cross-section, preferably arranged along most of the front extension of said device, more preferably in its whole front extension. The fit area  7  allows that most of the side  5  of anode  1  is tightly adjusted to said fit area  7 , covering at least 50% of said side or between 50% and 100%, thus providing enough surface for the fastening holes  6  that are preferably present on the sides of said fit area can set fastening points of anode  1  to the stiffening device  2 , thus making the anodic plate stiff. In addition, from  FIGS. 3 a  and 3 b    it is derived that one embodiment of the invention has a fit area  7  with tapered ends  8 . Said tapered ends  8  favor electrodepositing by exposing in a wide angle both surfaces of the anodic plate toward the adjacent cathodes, which facilitates the circulation of current between the electrodes and through the electrolytic means. 
         [0033]      FIG. 4  shows a preferred embodiment of the invention&#39;s system, where stiffening devices  2  are installed in most of both sides  5  of a set of anodes  1 , where said devices cover at least 50% of the extension of said sides  5  or preferably between 50% and 100%, covering in one embodiment the whole extension of said sides. From said figure it can be noted that between two anodes a space is provided where a cathodic plate is located, preferably with edge strips, where the stiffening devices  2  sets an equidistant separation between an anode and its adjacent cathode along the whole electrode, thus avoiding that it may become strained and, therefore, becomes joint to a cathode along the whole extension of its surface. 
         [0034]      FIG. 5  shows a scheme of the position occupied by anodes  1 , using the stiffening device  2  along with cathodes  9 , using edge strips  10 . In this context, it can be noted that the stiffening device sets an equidistant separation between anode  1  and cathode  9 , preventing this to change both along the electrode and while the anode is degraded thanks to the stiffening effect. Said separation, along with the effect of avoiding the strain of the anodic plate, allows to reducing the occurrence of short-circuits influencing on the formation of nodulations and, therefore, increasing the production of high-quality cathodes. 
         [0035]      FIGS. 7 a  and 7 b    show an embodiment of the invention comprising geometric characteristics of the stiffening device  2  that facilitate the passing of the current line through the different openings  11  that can be found along the device. In this context, the embodiment shown in  FIGS. 7 a  and 7 b    describe a discontinuous fit area, i.e. with openings  11  that allow to exposing a greater area of the anode for the purposes of providing a greater area for the circulation of current between the anode and cathode through an electrolytic means, while the stiffening effect provided by the device of the invention remains. 
         [0036]      FIGS. 8 a  and 8 b    show another embodiment of the invention that includes separating elements  12  located on one or both sides or inclined walls of the stiffening device, preferably in their rear portion, where in a preferred embodiment said separating elements  12  are integral part of said device. The main characteristics of the separating elements  12  are set for the contact area between anodes, so that the separation between two anodes is always constant and, therefore, the cathode located between anodes having a stiffening device  2  with separating elements  12  has a constant separation between adjacent anodes. In this context,  FIGS. 9 a  and 9 b    show an embodiment of the invention&#39;s system comprising the use of a stiffening device  2  with separating elements  12 , being it possible to appreciate the contact between said separating elements belonging to stiffening devices located in adjacent anodes. As a result, a configuration of anodes is obtained that keep constant separation between them, with this allowing to reducing the variations in the separation between anodes and cathodes, once they have been installed in the electrolytic cell. In addition, said separating elements  12  can be located along the whole rear extension of the stiffening device or at least in part of said extension, as it can be noted in  FIG. 8 b   . Preferably, said separating elements  12  are located at the center of the rear longitudinal extension of the stiffening agent  2 , so that to provide a balanced contact surface between anodes as shown in  FIGS. 9 a    and  9   b.    
         [0037]      FIG. 10  shows an embodiment of the invention&#39;s system that, out of incorporating stiffening devices  2  on the sides of each anode  1 , incorporates at least one central separating device  13  and there can be more of said devices in the cross-section extension of anode  1 . In this context, an embodiment of the central separating device  12  consists in a continuous ring surrounding the anode by both faces, both its upper portion by passing over the supporting bar and its lower edge. In addition, another embodiment of the central separating device  13  comprises a ring selected in its lower portion as a clamp, where this kind of device can be easily installed in the anode by inserting it from its bottom portion without the need of fastening both faces of the device. The central separating devices  13  strengthen the stiffening characteristics of the stiffening devices  2 , being useful in the case of anodes that present high wear and/or in anodes of great cross-section extension. In addition, in  FIG. 10  it can be noted that the central separating device  13  has fastening holes  6  along its extension, as well as in the fit area  7  of the stiffening device  2 , which allow to fastening the central separating device  13  to the anode surface, as well as joining the components of said device, specifically in its lower portion in the case of devices of the continuous ring type. 
         [0038]      FIGS. 11 a , 11 b  and 11 c    show an embodiment of the stiffening device  2  comprising a variable geometric configuration along the longitudinal extension of the device, defining a variable cross-section along said extension. In this context a variable cross-section of the stiffening device  2  defined by a side variable inclined wall  4  facilitates the circulation of the electrolytic means in the same way that when using the embodiment of the discontinuous fit area  7  enlarging the exposure angle of the electrode surface. This—by facilitating the circulation of the electrolyte—allows to improving the passing of current without interrupting the flow lines and favoring the settlement of metal in the cathode. 
         [0039]      FIGS. 12 a  and 12 b    show an embodiment of the stiffening device  2  where the fit area  2 , formed by the joining of the inclined side walls  4  in the form of “V”, has been reinforced. As it can be noted, in this context—especially in  FIG. 12 b   —the fit area  7 , according to this embodiment, does not project from the joining of the inclined side walls  4  as in the invention&#39;s preferred embodiment, but it consists in a bore or groove of rectangular or square cross-section arranged within the side walls of the device located in the symmetry axis of the cross-section thereof, specifically in its front portion. This results in the fit area  7  not having projecting edges as in the preferred embodiment shown in  FIG. 3 b   , thus reducing the weakness of said edges before mechanic efforts, as well as providing side walls of the stiffening device that describe a surface of greater continuity, which favors the circulation of current and, therefore, electrodepositing. 
         [0040]    Finally, an embodiment of the stiffened device according to the embodiment, as well as of the system incorporating at least one of those devices, has a lower spring of triangular shape, preferably incorporated to the device, which has a basis that, depending on the dimensions of the electrolytic cell, gets in contact with the bottom of said cell, offering higher stability to the anodes. In addition, said lower support has inclined walls destined to benefit the installation and deinstallation of the adjacent cathodes, preventing them to hit the lower portion of the anode. 
         [0041]    According to the previous descriptions, any of the embodiments already presented of the stiffening device and, therefore, of the stiffening system, consisting for example in a combination of one or more characteristics as shown above and/or any component known in the art, is considered within the protection scope of this application.