Abstract:
A filter plate for a filter press assembly is disclosed which is structured with replaceable wear elements to increase the resistance of the filter plate to degradation caused by processing of abrasive filtrates. While the wear elements may eventually degrade due to contact with abrasive filtrates, the wear elements are easily replaceable, thereby prolonging the life of the filter plate and reducing operating costs. The replaceable wear elements may be used to retrofit existing filter plates.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to U.S. provisional patent application Serial No. 60/261,734 filed Jan. 16, 2001. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to filter press plates used in a filter press assembly, and more specifically relates to filter press plates configured with replaceable, wear resistant members associated with the filtrate ports of a filter plate which extend the life of the filter press plate. 
     2. Description of the Related Art 
     Filter press assemblies are used in many industries to process feed slurries resulting from a given process, such as mineral concentrate dewatering. Filter press assemblies involve separating a solids component from the liquid component of the feed slurry to produce a solid, dewatered cake of material. The remaining or separated liquid filtrate is channeled out of the filter press assembly for re-processing or disposal. 
     A filter press assembly comprises a plurality of planar filter plates which are aligned and adjacently arranged in a horizontal stack. Each filter plate has a peripheral edge or frame and one or more faces recessed from the rim or frame so that when two filter plates are positioned adjacent one another, a space is formed therebetween. Each filter plate also has a feed port which, when the filter plates are aligned and in adjacent arrangement, provides a feed channel into which a feed slurry is introduced. 
     The feed slurry enters the space formed between adjacent filter plates and the larger solids of the slurry are deposited while the liquid component drains away from the space and is channeled away from the filter press assembly. Typically, each face of a filter plate is covered with an arrangement of raised bosses or pips which form channels therebetween through which the liquid filtrate is communicated toward openings formed near the periphery of the filter plate. The openings are in fluid communication with a filtrate outlet through which the filtrate then empties. 
     In operation, each filter plate is typically covered with a filter media, usually made of cloth, and the feed slurry is introduced between adjacent layers of filter media. High velocity air is introduced between adjacent filter plates to air sweep the solids accumulating between the two layers of filter media and to force the filtrate through the filter media. A substantially dry and solid cake of solids material results. The liquid filtrate, being subjected to high velocity air, passes through the filter media and is channeled along the face of the filter plate at high velocity. The filtrate then enters into the openings and through the filtrate outlet at high velocity. 
     When processing feed slurries which have abrasive components that are small enough to pass through the filter media, or through holes worn in the filter media, the high-velocity filtrate moving along the faces of the filter plate and into the filtrate openings cause a significant amount of damage to the filter plate. Not only do the openings become worn and degraded, but the filtrate outlet becomes abraded and worn. Eventually the filtrate openings and filtrate outlets of the filter plate become so worn that leakage occurs between adjacent filter plates and the filter press assembly is unable to operate efficiently, or at all. The worn filter plates cannot be repaired and must be discarded and replaced with new filter plates. Replacing the filter plates is very expensive. 
     Thus, it would be advantageous in the art to structure a filter press plate to have increased resistance to degradation caused by the movement of high velocity abrasive filtrate and which would enable fast, easy and inexpensive repair of the filter plate when degradation does occur so that the life of the filter plate can be extended, thereby reducing operating costs. 
     BRIEF SUMMARY OF THE INVENTION 
     In accordance with the present invention, a filter press plate is structured with replaceable wear elements which provide wear resistance to the filtrate openings and filtrate outlet of the filter plate, thereby extending the life of the filter plate and facilitating easy and inexpensive repair of the filter plate when degradation of the wear element occurs. 
     In a filter plate of the present invention, the filter plate is structured to receive inserted replaceable wear elements in concert with the filtrate opening or outlet of the filter plate. The wear elements are preferably formed of a material which is particularly resistant to wear or degradation that may be caused by contact with high-velocity abrasive material. The wear elements are positioned on the filter plate to receive abrasive filtrate in transit to and through the filtrate outlet of the filter plate. Thus, the wear elements are subjected to the degrading effects of the abrasive filtrate, in the area of the filter plate where the most significant amount of degradation occurs, and the replaceability of the wear elements enables the filter plate to essentially be refurbished for further use, thereby extending the conventional life of the filter plate. 
     The wear elements of the present invention comprise one or more wear plates configured to fit over a portion of the recessed face of a filter plate, a filtrate channel insert and a filtrate outlet insert. The wear plates, filtrate channel insert and filtrate outlet insert are each constructed of a suitable wear-resistant material to withstand contact with abrasive material, but each is also readily replaceable when degraded. 
     A filter plate is described being structured with wear elements in accordance with the present invention. However, the wear elements of the present invention are also adaptable for retrofitting to virtually any type, style or manufacture of filter press plate. 
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
     In the drawings, which illustrate what is currently considered to be the best mode for carrying out the present invention: 
     FIG. 1 is a perspective view of a filter press plate of the prior art, certain details being shown in phantom; 
     FIG. 2 is a partial view in cross section of the prior art filter press plate shown in FIG. 1, taken at line  2 — 2 ; 
     FIG. 3 is a partial view of a corner of a filter press plate of the present invention, certain elements being shown in phantom; 
     FIG. 4 is a view in cross section of the filter press plate shown in FIG. 3, taken at line  4 — 4 ; 
     FIG. 5 is a perspective view of a filtrate channel insert of the present invention; 
     FIG. 6 is a view in cross section of a wear plate of the present invention; 
     FIG. 7 is a perspective view of a filtrate outlet insert of the present invention; 
     FIG. 8 is a view in elevation of the filter press plate shown in FIG. 3, taken at line  8 — 8 ; 
     FIG. 9 is a view in cross section of the filter press plate shown in FIG. 3, taken at line  9 — 9 ; 
     FIG. 10 is a view in elevation of the filter press plate shown in FIG. 3 showing the position and orientation of an internal filtrate outlet configuration of the present invention; 
     FIG. 11 is a view in cross section of the filter plate shown in FIG. 9, taken at line  11 — 11 ; and 
     FIG. 12 is a view is cross section of a filter plate illustrating the relative dimensions of the wear elements. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIGS. 1 and 2 illustrate a typical filter plate  10  of the prior art. It can be seen that a filter plate  10  is generally planar, having four sides  12 ,  14 ,  16 ,  18  which form a frame  20  about the periphery of the body  21  of the filter plate  10  and two opposing recessed faces  22 ,  24  (only one being viewable from the perspective view of FIG.  1 ). The peripheral edge  26 ,  28  of the frame  20  surrounding each recessed face  22 ,  24 , respectively, extends above the plane of each face  22 ,  24 , as best seen in FIG.  2 . 
     Each recessed face  22 ,  24  of the filter plate  10  may be configured with a plurality of raised bosses or pips  30  (only a representative few being shown) which extend above the surface level of the recessed faces  22 ,  24 , thereby forming channels  25  between which filtrate is communicated. Notably, some filter plates, known as membrane plates, are fitted with an elastomer membrane which overlies the planar recessed face of the body  21  and is formed with raised pips that provide the same fluid channels. 
     The filter plate  10  is also constructed with a feed port  32  through which feed slurry is introduced and a passageway for egress of filtrate, typically comprising one or more filtrate outlets  34  through which filtrate is removed from the recessed faces  22 ,  24 . Notably, the feed port  32  and filtrate outlets  34  may be located elsewhere about the filter plate  10  than is illustrated in FIGS. 1 and 2. The filter plate  10  is usually covered in its entirety with filter media  36 , which is shown in FIG. 1 covering only one corner of the filter plate  10 . The feed port  32  and filtrate outlets  34  are not covered. 
     Filtrate openings  38  are formed along the periphery of the recessed faces  22 ,  24  near the frame  20 . The filtrate openings  38  are in fluid communication with a filtrate channel  40  (shown in phantom) formed in the filter plate  10 . The filtrate channel  40  is in fluid communication with a filtrate outlet  34  (FIG. 1) when used. While not shown, it is understood that the filtrate outlets  34  of adjacently stacked filter plates form a continuous fluid pathway through which the filtrate moves to exit the filter press assembly. Alternatively, filtrate is removed from the filtrate channel  40  through a manifold to which is connected each filtrate channel  40  of each filter plate in the press. 
     In prior art filter plates, as shown in FIGS. 1 and 2, the filtrate channel  40  is formed during the molding of the filter plate  10  or is machined in the filter plate  10  after formation of the plate. The filtrate openings  38  are usually machined into the filter plate  10  after formation. When processing feed slurries which contain abrasive particulate matter small enough to pass through the filter media  36 , or through holes worn in the filter media  36 , the abrasive particulates and high-velocity filtrate passing through the filtrate openings  38  and filtrate channel  40  cause degradation of the filtrate openings  38 , filtrate channel  40  and filtrate outlet  34 . Once degraded, the filter plate will begin to leak and must be discarded and replaced in its entirety. This problem is solved by the present invention. 
     The present invention is illustrated in FIGS. 3-11 and comprises a system of wear elements positioned in a filter plate  50  to reduce degradation of the filter plate  50 , particularly when processing abrasive filtrate. When the wear elements are eventually degraded, they can be easily and inexpensively replaced to extend the life of the filter plate  50 . 
     The wear elements of the present invention comprise one or more replaceable wear plates  52  which are sized and configured to be positioned along the recessed face or faces  54 ,  56  (FIG. 4) of the filter plate  50  near the peripheral edge  58  of the frame  60  of the filter plate  50 . 
     The filter plate  50  may be molded, or later machined, with an opening  62  through the body  53  of the filter plate  50 , as shown in FIG.  4 . The opening  62  is configured and sized to receive the wear plates  52  therein so that the outer surface  64 ,  66  of each wear plate  52  is aligned with the respective planar surface of the recessed face  54 ,  56  to which it is attached, thereby facilitating the flow of filtrate between the raised pips  30  and along the outer surface  64 ,  66  of the wear plates  52 . 
     Each wear plate  52  may be formed with filtrate openings  70  into which the filtrate drains from the outer surface  64 ,  66 , respectively, of each wear plate  52 . Notably, it may be desirable in some applications to provide one recessed face  54  or  56  with a wear plate  52  having filtrate openings  70  while providing the opposing recessed face with a wear plate having no filtrate openings to selectively direct or determine flow rates. 
     As shown in FIG. 4, two wear plates  52 , each positioned along an opposing recessed face  54 ,  56  of the filter plate  50 , are aligned on either side of the body  53  of the filter plate  50  so that the two wear plates  52  may be secured together by, for example, a bolt  72  which extends through both wear plates  52  to hold them together. A gasket  74  may be positioned between the wear plates  52  and the opening  62  to provide a fluid-tight seal. 
     The wear elements of the present invention also include a replaceable wear-resistant filtrate channel insert  80  which is sized to be received in the pre-formed filtrate channel  82  (shown in phantom in FIG. 3) of the filter plate  50 . As shown in FIGS. 3 and 4, the pre-formed filtrate channel  82  includes a portion with a cylindrical closed cross section located between the filtrate outlet  98  and the recessed faces  55 . The pre-formed filtrate channel  82  may be formed in the filter plate  50  at the time the filter plate  50  is molded by, for example, positioning a rod into the mold, which is later removed. Alternatively, the channel  82  may be machined into the filter plate  50  by known methods. 
     The filtrate channel insert  80 , further illustrated in FIG. 5, is made of wear-resistant material and is formed with apertures  84  which, when the filtrate channel insert  80  is positioned within the pre-formed filtrate channel  82 , align with the filtrate openings  70  of the wear plates  52 , as shown in FIG.  4 . 
     As more clearly shown in FIG. 6, each wear plate  52  is particularly configured and molded to assure that a tight fit is provided between the filtrate openings  70  of the wear plates and the apertures  84  of the filtrate channel insert  80  so that filtrate does not leak between the wear plate  52  and the filtrate channel insert  80  in the area  76  between and surrounding the filtrate openings  70  and apertures  84 . While separable, paired wear plates  52  provide a simplified means of providing wear elements in accordance with the present invention, it is also within the scope of the invention to provide a wear plate of singular or unitary construction, as suggested in phantom in FIG. 4 where, for example, a bridge portion  78  extends between opposingly-oriented sets of filtrate openings  70  and partially encircles the filtrate channel insert  80 . Other configurations of the wear elements are also suitable for the invention. 
     As shown in FIG. 5, the filtrate channel insert  80  has a first closed end  85 , which is positioned within the filter plate  50 , and a second end  86  which may be open or closed, as described further hereinafter. Aligned side openings  83  (shown in phantom in FIG. 5) may be formed through the wall of the filtrate channel insert  80  for reasons that are described further hereinafter. 
     The filtrate channel insert  80  may be formed as a single ply or layer of wear-resistant material as suggested in FIG. 5; or, as illustrated in FIG. 4, may be formed as a two-ply or dual layer configuration having an outer layer  88  of relatively less wear-resistant material and an inner layer  90  of relatively more wear-resistant material. By way of example only, the outer layer  88  may be made of thin stainless steel and the inner layer  90  may be formed from high-abrasion grade rubber or urethane, such as urethane having a durometer of about  60 D. Innumerable other materials are suitable, however, and may be employed in the manufacture of the filtrate channel insert  80 . 
     The filtrate channel insert  80  may be held in the filtrate channel  82  by friction fit. Alternatively, the filtrate channel insert  80  may be configured in such a way as to provide stabilizing contact with the filter plate  50  to keep the filtrate channel insert  80  securely in place within the filtrate channel  82  (i.e., to maintain the alignment of the apertures  84  with the filtrate openings  70  of the wear plates  52 ). 
     By way of example, FIG. 5 illustrates that the second end  86  of the filtrate channel insert  80  may be configured with one or more splines  87  that, when the filtrate channel insert  80  is inserted in the pre-formed filtrate channel  82 , register with notches  89  machined into the frame  60 , as shown in FIG.  8 . By further way of example, removable anchor pins or screws could be inserted through the frame to engage the filtrate channel insert  80  therewith. Further by way of example, the second end  86  of the filtrate channel insert  80  could be configured with a hexagonal, ovate or other geometrically-configured outer surface to securely engage a similarly-shaped machined opening in the frame  60  of the filter plate  50 . 
     As shown in FIG. 8, the second end  86  of the wear-resistant filtrate channel insert  80  may be open to provide an end outlet  94  which serves as the filtrate outlet in what may be termed an external orientation. In other words, the filtrate is caused to exit from the filter plate  50  in a direction normal to the direction of slurry flow through the feed port  32  (FIG.  1 ). When multiple numbers of filter plates are in a filter press, the end outlet  94  of each filter plate  50  is connected to a manifold to carry the filtrate away from the filter press. 
     Alternatively, as suggested in phantom in FIG. 3, an internally-oriented filtrate outlet  98  may be employed as the means for providing egress for the filtrate. As noted previously, when an internally-oriented filtrate outlet  98  is employed, the aligned filtrate outlets of adjacently stacked filter plates form a continuous fluid pathway through the filter press for egress of filtrate in a direction parallel to the flow of slurry through the feed ports  32  (FIG.  1 ). 
     As shown more specifically in FIGS.  7  and  9 - 11 , the wear elements of the present invention may further include a replaceable internal filtrate outlet insert  100  which is configured and positioned to intersect with the filtrate channel insert  80  to provide a fluid pathway therewith. The filtrate outlet insert  100 , as shown separately in FIG. 7, may generally be cylindrical in lateral cross section (although other shapes or dimensions are also suitable) and is positionable within a pre-formed filtrate outlet channel  101  (FIG. 3) formed in the filter plate  50 . The filtrate outlet channel  101  is formed in the filter plate  50  to intersect with the filtrate channel  82  at right angles thereto. 
     As best seen in FIGS. 7,  9  and  10 , the filtrate outlet insert  100  is formed with a first open end  102 , which is oriented to open on one side  104  of the filter plate  50 , and a second open end  106 , which is oriented to open on the other side  108  of the filter plate  50 . The filtrate outlet insert  100  is also, in the embodiment shown, formed with dual openings  110  and  112  through the wall thereof. The dual openings  110 ,  112  are aligned to receive therethrough the filtrate channel insert  80  (shown in phantom in FIGS. 7 and 10) so that the side openings  83  (FIG. 5) of the filtrate channel insert  80  open into the bore  116  of the filtrate outlet insert  100  to provide a continuous fluid pathway for the filtrate moving from the openings  70  of the wear plates  52 , through the filtrate channel insert  80  and out through the filtrate outlet insert  100 . The illustrated arrangement of the filtrate channel insert  80  and filtrate outlet insert  100  is by way of example only, and other arrangements or configurations are suitable. 
     Like the filtrate channel insert  80 , the filtrate outlet insert  100  is made of wear-resistant material and may be either a single ply construction, as suggested in FIG. 7, or a double ply construction, as shown in FIGS. 9 and 11. The filtrate outlet insert  100  may be a double layer construction of, for example, an outer layer  120  of NiHard and an inner layer  122  of polybutylene. Other wear-resistant materials are suitable for use. 
     The filtrate outlet insert  100  is held in place by friction fit and by virtue of its intersecting connection with the filtrate channel insert  80 . As shown in FIG. 11 when a replaceable filtrate outlet insert  100  is employed in the filter plate  50  for internal filtrate drainage, the filtrate channel insert  80  is closed at the second end  86  thereof. The second end  86  may be stoppered or integrally formed with a plug  126 , shown in phantom in FIG.  10 . Preferably, however, the filtrate channel insert  80 , as shown in FIG. 11, is formed at its second end  86  with portion having a solid core  128  which terminates flush with the wall  130  of the bore  116  of the filtrate outlet insert  100 . 
     It is important to note that the relative size or dimension, and the arrangement, of the filtrate outlet insert  100  and the filtrate channel insert  80  shown in FIGS. 7,  10  and  11  is suitable and adequate for filter press assemblies of fewer filter plates, where pressure conditions through the aligned internally-oriented filtrate outlets  98  is less. However, as the number of filter plates in the filter press assembly increases, so do the pressure conditions in the aligned internally-oriented filtrate outlets  98  through which the filtrate flows. In such instances, it is more important that the size or dimension of the filtrate channel insert  80  be reduced relative to the filtrate outlet insert  100  so that the filtrate channel insert  80  does not present an obstruction of the filtrate outlet  98 , thereby adversely affecting the pressure conditions in the aligned filtrate outlets  98 . This arrangement is illustrated in FIG.  12 . 
     The wear elements of the present invention provide a means for protecting and extending the life of a filter plate. The wear plate, filtrate channel insert and filtrate outlet insert may be used singly or in any combination and may be adapted to any kind, manufacture or style of filter plate. Thus, those skilled in the art will understand that the wear elements of the invention may be adapted to suit any use and the illustrations herein are not meant to limit the scope of the invention.